Author: RR

New ASCO Guideline Recommends Germline Testing in ALL Newly Diagnosed Breast Cancer Patients 65 Years or Younger

RR

SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. It is estimated that in the US, approximately 310,720 new cases of female breast cancer will be diagnosed in 2024, and about 42,250 individuals will die of the disease, largely due to metastatic recurrence.

The availability of multigene panel testing and next-generation sequencing can change the landscape of cancer prevention and treatment. However, there is lack of guidance for clinicians on whom to test and/or which genes to include in germline genetic testing panels for Pathogenic Variants.

The American Society of Clinical Oncology along with the Society of Surgical Oncology on January 4, 2024 provided new clinical practice guideline for clinicians and other Health Care Providers, regarding the role of germline mutation testing in patients with breast cancer, based on the best available evidence. These recommendations were developed based on a systematic review of 47 articles that met eligibility criteria for the germline mutation testing recommendations, and 18 articles that met eligibility criteria for the genetic counseling recommendations.

The guideline addressed the following question: Which patients with breast cancer should have germline genetic testing for Pathogenic Variants (PVs) in cancer susceptibility genes?

Question 1. Should clinicians offer BRCA1/2 testing to all patients with newly diagnosed breast cancer?
Recommendation 1.1
All patients newly diagnosed with breast cancer with Stage I-III or de novo Stage IV/metastatic disease who are 65 years or younger at diagnosis should be offered BRCA1/2 testing.
Recommendation 1.2
All patients newly diagnosed with breast cancer with Stage I-III or de novo Stage IV/metastatic disease who are older than age 65 should be offered BRCA1/2 testing if:
a) They are candidates for poly(ADP–ribose) polymerase (PARP) inhibitor therapy for early-stage or metastatic disease.
b) They have triple-negative breast cancer.
c) Their personal or family history suggests the possibility of a pathogenic variant.
d) They were assigned male sex at birth.
e) They are of Ashkenazi Jewish ancestry or are members of a population with an increased prevalence of founder mutations.
Recommendation 1.3
Patients undergoing BRCA1/2 testing should also be offered testing for other cancer predisposition genes as suggested by their personal or family history. Consultation with a provider experienced in clinical cancer genetics can help guide this decision-making and should be made available to patients when possible.

Question 2. Should all people with recurrent disease, local or metastatic, or with second breast primary, be offered BRCA1/2 testing?
Recommendation 2.1
All patients with recurrent breast cancer (local or metastatic) who are candidates for PARP inhibitor therapy should be offered BRCA1/2 testing regardless of family history.
Qualifying statement.
Small single-arm studies show that oral PARP inhibitor therapy demonstrates high response rates in women with metastatic breast cancer and germline pathogenic variants in PALB2.
Recommendation 2.2
BRCA1/2 testing should be offered to patients with a second primary cancer either in the contralateral or ipsilateral breast.

Question 3. Should people with a personal history of breast cancer (and no active disease) be offered BRCA1/2 testing?
Recommendation 3.1
All patients with a personal history of breast cancer diagnosed 65 years or less who are without active disease should be offered BRCA1/2 testing if the result will inform personal risk management or family risk assessment.
Recommendation 3.2
All patients with a personal history of breast cancer diagnosed over age 65 with no active disease, who meet one of the following criteria, should be offered BRCA1/2 testing if the result will inform personal risk management or family risk assessment:
a) Their personal or family history suggests the possibility of a pathogenic variant.
b) They were assigned male sex at birth.
c) They had triple-negative breast cancer.
d) They are of Ashkenazi Jewish ancestry or are members of a population with an increased prevalence of founder mutations.

Question 4. What is the value of testing patients with a diagnosis of breast cancer for breast cancer predisposition genes other than BRCA1/2?
Recommendation 4.1
Testing for high penetrance genes beyond BRCA1/2, including PALB2, TP53, PTEN, STK11, and CDH1, could inform medical therapy, influence surgical decision making, refine estimates of risks of second primary cancer, and inform family risk assessment, and thus should be offered to appropriate patients.
Recommendation 4.2
Testing for moderate penetrance breast cancer genes currently offers no benefits for treatment of the index breast cancer but may inform risks of second primary cancer or family risk assessment, and thus may be offered to appropriate patients who are undergoing BRCA1/2 testing.
Recommendation 4.3
If a multi-gene panel is ordered, the specific panel chosen should take into account the patients personal and family history. Consultation with a provider experienced in clinical cancer genetics can be helpful in selecting a specific multi-gene panel or interpreting its results and should be made available to patients when possible.

Question 5. How should patients with breast cancer considering genetic testing be counseled?
Recommendation 5.1
Patients undergoing genetic testing should be given sufficient information before testing to provide informed consent.
Recommendation 5.2
Patients with pathogenic variants should be provided with individualized post-test genetic counseling and offered referral to a provider experienced in clinical cancer genetics.
Recommendation 5.3
Variants of uncertain significance should not alter management. Patients should be made aware that variants of uncertain significance may be reclassified as being pathogenic, and they should understand that periodic follow up is necessary. Consultation with a provider experienced in clinical cancer genetics can be helpful and should be made available to patients when possible.
Recommendation 5.4
Patients without a pathogenic variant on genetic testing may still benefit from counseling, if there is a significant family history of cancer, and referral to a provider experienced in clinical cancer genetics is recommended.

ASCO believes that cancer clinical trials are vital to inform medical decisions and improve cancer care, and that all patients should have the opportunity to participate.

Germline Testing in Patients With Breast Cancer: ASCO–Society of Surgical Oncology Guideline. Bedrosian I, MD , Somerfield MR, PhD, Achatz MI, et al. J Clinical Oncol. 2024;42:584-604.

Sotorasib plus Panitumumab in Refractory Colorectal Cancer with Mutated KRAS G12C

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SUMMARY: Colorectal Cancer (CRC) is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 153,020 new cases of CRC were diagnosed in the United States in 2023 and about 52,550 patients died of the disease. The lifetime risk of developing CRC is about 1 in 23.

Approximately 15-25% of the patients with CRC present with metastatic disease at the time of diagnosis (synchronous metastases) and 50-60% of the patients with CRC will develop metastatic disease during the course of their illness. First line treatment of metastatic CRC includes Oxaliplatin or Irinotecan, in combination with a Fluoropyrimidine and Leucovorin (FOLFOX or FOLFIRI respectively), along with a VEGF targeting agent such as Bevacizumab or EGFR targeting agents such as Cetuximab and Panitumumab. Patients with Stage IV colorectal cancer are now routinely analyzed for extended RAS and BRAF mutations. KRAS mutations are predictive of resistance to EGFR targeted therapy. Patients who progress following these therapies are considered to have refractory disease. These patients sometimes are rechallenged with previously administered chemotherapeutic agents, but often receive STIVARGA® (Regorafenib), an oral multikinase inhibitor with antiangiogenic activity, or LONSURF® (a fixed dose combination of Trifluridine and Tipiracil). These therapies however have shown limited efficacy.

The KRAS (Kirsten rat sarcoma viral oncogene homologue) proto-oncogene encodes a protein that is a member of the small GTPase super family. The KRAS gene provides instructions for making the KRAS protein, which is a part of a signaling pathway known as the RAS/MAPK pathway. By relaying signals from outside the cell to the cell nucleus, the protein instructs the cell to grow, divide and differentiate. KRAS gene is in the Ras family of oncogenes, which also includes two other genes, HRAS and NRAS. When mutated, oncogenes have the potential to change normal cells cancerous. KRAS is the most frequently mutated oncogene in human cancers and are often associated with resistance to targeted therapies and poor outcomes. The KRAS G12C mutation occurs in approximately 12-15% of Non Small Cell Lung Cancers (NSCLC) and in 3-5% of colorectal cancers and other solid cancers. G12C is a single point mutation with a Glycine-to-Cysteine substitution at codon 12. This substitution favors the activated state of KRAS, amplifying signaling pathways that lead to oncogenesis. Currently, no targeted therapies driven by a positive-selection biomarker are approved specifically for the treatment of patients with KRAS-mutated colorectal cancer.

Sotorasib (LUMAKRAS®) is a small molecule that specifically and irreversibly inhibits KRAS G12C protein and traps KRAS G12C in the inactive GDP-bound state, thus blocking downstream proliferation and survival signaling. Unlike the efficacy of single-agent KRAS G12C inhibitors in Non Small Cell Lung Cancer with KRAS G12C mutation, KRAS G12C inhibition alone has limited activity in patients with colorectal cancer. This has been attributed to upstream reactivation of the Epidermal Growth Factor Receptor (EGFR) pathway resulting in treatment-induced resistance, following selective inhibition of KRAS G12C. However, dual KRAS G12C and EGFR blockade can overcome treatment resistance in patients with colorectal cancer with KRAS G12C mutation. In the CodeBreaK 101 Phase 1b trial involving patients with chemorefractory colorectal cancer with mutated KRAS G12C, the Response Rate was 30% with Sotorasib plus Panitumumab, as compared with 9.7% with Sotorasib monotherapy.

CodeBreaK 300 trial is an international, multicenter, open-label, randomized, active-controlled Phase III study, conducted to evaluate the efficacy and safety of two different doses of Sotorasib (960 mg and 240 mg) in combination with Panitumumab as compared with the investigator’s choice of standard-care therapy (Trifluridine-Tipiracil or Regorafenib) in patients with chemorefractory metastatic colorectal cancer with KRAS G12C mutation. A lower dose of Sotorasib 240 mg orally once daily was tested in this study because of the nonlinear pharmacokinetic properties of Sotorasib. A total of 160 patients were randomly assigned in a 1:1:1 ratio to receive Sotorasib 960 mg orally once daily plus Panitumumab 6 mg/kg IV every 2 weeks (the 960 mg Sotorasib/Panitumumab group; N=53), Sotorasib 240 mg orally once daily plus Panitumumab (the 240 mg Sotorasib/Panitumumab group; N=53), with each treatment cycle repeating every 28 days, or the investigator’s choice of standard of care therapy which could be either Trifluridine-Tipiracil 35 mg/m2 (up to a maximum of 80 mg per dose) orally twice daily on days 1-5 and days 8-12 every 28 days, or Regorafenib 160 mg orally once daily for the first 21 days of each 28-day cycle (N=54). Treatment continued until disease progression or unacceptable toxicities. The median age was 61 years and majority of patients had more than 2 or more lines of previous anti-cancer therapy. KRAS G12C mutation was confirmed by prospective central molecular testing. Randomization was stratified according to previous use of antiangiogenic therapy, the time from initial diagnosis of metastatic disease to randomization and ECOG-PS. The Primary end point was Progression Free Survival (PFS) as assessed by Blinded Independent Central Review (BICR). Key Secondary end points included Overall Survival (OS) and Objective Response Rate (ORR).

After a median follow up of 7.8 months, both Sotorasib combinations (960 mg and 240 mg) plus Panitumumab demonstrated significantly longer PFS compared to standard of care therapy. The median PFS was 5.6 months and 3.9 months in the 960 mg Sotorasib/Panitumumab and 240 mg Sotorasib/Panitumumab groups, respectively, as compared with 2.2 months in the standard of care group (HR for 960 mg group=0 49; P=0.006) (HR for 240 mg group=0.58; P=0.03). The improvement in PFS was observed across key subgroups, including tumor sideness/primary tumor location, prior lines of therapy, and the presence or absence of liver metastases. The Objective Response Rate was 26.4%, 5.7%, and 0% in the 960 mg Sotorasib/Panitumumab, 240 mg Sotorasib/Panitumumab, and standard of care groups, respectively. Overall survival data is immature. While this trial was not powered to compare the two Sotorasib/Panitumumab groups directly, the 960-mg dose appeared to yield more clinically significant benefits than the 240-mg dose, across all efficacy endpoints, without additional toxic effects. Grade 3 or higher treatment-related adverse events occurred in 35.8%, 30.2%, and 43.1% of patients, respectively. Skin-related toxic effects and hypomagnesemia were the most common adverse events observed with Sotorasib/Panitumumab.

It was concluded from this study that both doses of Sotorasib (960 mg and 240 mg) in combination with Panitumumab resulted in significantly longer Progression Free Survival and a higher incidence of Response Rate than standard treatment. Ongoing analysis and longer follow up will provide additional insights into Overall Survival outcomes.

Sotorasib plus Panitumumab in Refractory Colorectal Cancer with Mutated KRAS G12C. Fakih MG, Salvatore L, Esaki T, et al. N Engl J Med 2023;389:2125-2139.

FDA Approves ALECENSA® as Adjuvant Treatment for ALK-Positive Non Small Cell Lung Cancer

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SUMMARY: The FDA on April 18, 2024, approved ALECENSA® (Alectinib) for adjuvant treatment following tumor resection in patients with Anaplastic Lymphoma Kinase (ALK)-positive Non Small Cell Lung Cancer (NSCLC), as detected by an FDA-approved test. Lung cancer is the second most common cancer in both men and women and accounts for about 12% of all new cancers and 21% of all cancer deaths. The American Cancer Society estimates that for 2024 about 234,580 new cases of lung cancer will be diagnosed and about 125,070 patients will die of the disease. Non Small Cell Lung Cancer (NSCLC) accounts for approximately 85% of all lung cancers. Of the three main subtypes of Non Small Cell Lung Cancer (NSCLC), 25% are Squamous cell carcinomas, 40% are Adenocarcinomas and 10% are Large cell carcinomas.

The discovery of rearrangements of the Anaplastic Lymphoma Kinase (ALK) gene in some patients with advanced NSCLC and adenocarcinoma histology, led to the development of agents such as XALKORI® (Crizotinib), ZYKADIA® (Ceritinib), ALECENSA® (Alectinib), ALUNBRIG® (Brigatinib) and LORBRENA® (Lorlatinib), with promising results. It has become clear that appropriate molecularly targeted therapy for tumors with a molecular abnormality, results in the best outcomes. According to the US Lung Cancer Mutation Consortium (LCMC), two thirds of patients with advanced adenocarcinoma of the lung, have a molecular driver abnormality. The most common oncogenic drivers in patients with advanced adenocarcinoma of the lung are, KRAS in 25%, EGFR in 21% and ALK in 5%, as well as other mutations in BRAF, HER2, AKT1, fusions involving RET and ROS oncogenes and MET gene alterations. These mutations are mutually exclusive and the presence of two simultaneous mutations, are rare.

Patients with ALK-positive NSCLC tend be younger nonsmokers and present with more advanced disease. Approximately 50-60% of these patients develop brain metastases. These patients are often treated with ALK TKIs that cross the blood brain barrier. Patients with early stage resected ALK-positive NSCLC receive adjuvant treatment with platinum-based combination chemotherapy, with 5-year survival ranging from 70% for Stage IB disease to about 35% for Stage IIIA disease, with associated chemotherapy related toxicities.

Alectinib is a potent, second-generation ALK Tyrosine Kinase Inhibitor, and is effective against several ALK mutations that confer resistance to Crizotinib. In the Phase III, randomized ALEX trial, treatment naïve patients with advanced ALK-positive NSCLC who received Alectinib had significantly longer Progression Free Survival and 5-year Overall Survival, compared to those who received Crizotinib, with substantial CNS activity.

The ADAURA trial investigated adjuvant TAGRISSO® (Osimertinib), a third-generation EGFR TKI, in patients with resected EGFR-mutated NSCLC of stage IB, II, or IIIA. Results showed benefits in Disease-Free and Overall Survival, along with reduced CNS recurrence. The ALINA trial similarly assessed the efficacy of Alectinib, in resected ALK-rearranged NSCLC.

ALINA is a global, open-label, randomized, Phase III trial, conducted to investigate the efficacy and safety of adjuvant Alectinib as compared with standard chemotherapy in patients with resected ALK-positive NSCLC. In this study, 257 eligible enrolled patients (N=257) were randomly assigned 4-12 weeks after patients had undergone complete surgical resection (lobectomy, sleeve lobectomy, bilobectomy, or pneumonectomy) in a 1:1 ratio to receive Alectinib 600 mg orally twice daily or platinum-based chemotherapy IV every 21 days for 4 cycles. Alectinib was given for 24 months. Chemotherapy consisted of Cisplatin 75 mg/m2 IV on day 1 of each cycle, plus Vinorelbine 25 mg/m2 IV on days 1 and 8, Gemcitabine 1250 mg/m2 IV on days 1 and 8, or Pemetrexed 500 mg/m2 on day 1. In the event of Cisplatin intolerance, Carboplatin AUC 5 or 6 IV was substituted. Eligible patients had completely resected, histologically confirmed Stage IB (tumors 4 cm or more), II, or IIIA NSCLC, and randomization was stratified according to disease stage and race (Asian versus non-Asian). A total of 231 patients had Stage II or IIIA disease, 116 in the Alectinib group and 115 in the chemotherapy group. The Primary end point was Disease Free Survival (DFS), tested hierarchically among patients with Stage II or IIIA disease and then in the Intention-To-Treat (ITT) population. Secondary end points included CNS Disease Free Survival, Overall Survival, and Safety. The median duration of follow up was 28 months.

The DFS among patients with Stage II or IIIA disease at 2 years was 93.8% in the Alectinib group and 63.0% in the chemotherapy group, and 88.3% and 53.3% respectively at 3 years. The Hazard Ratio for disease recurrence or death was 0.24 (P<0.001), which corresponds to a 76% lower risk with adjuvant Alectinib than with chemotherapy. This DFS benefit was seen consistently across prespecified subgroups, including those defined according to disease stage, race, sex, and smoking status. An exploratory analysis showed a clinically meaningful prolongation of CNS Disease Free Survival with Alectinib. Fewer patients in the Alectinib group had CNS recurrence compared to the chemotherapy group (3.1% versus 11%), consistent with the intracranial efficacy of Alectinib in advanced NSCLC. Overall Survival data were immature at the time of data-cutoff.

The authors concluded that Adjuvant Alectinib significantly improved Disease Free Survival, as compared with platinum-based chemotherapy, among patients with resected ALK-positive NSCLC of Stage IB, II, or IIIA, with few discontinuations due to adverse events. The researchers added that this study reinforces the need for implementation of biomarker testing for ALK alterations, across all stages of NSCLC.

Alectinib in Resected ALK-Positive Non–Small-Cell Lung Cancer. Wu Y-L, Dziadziuszko R, Ahn JS, et al. for the ALINA Investigators. N Engl J Med 2024;390:1265-1276.

Long Term Benefits of RUBRACA® Maintenance in Newly Diagnosed Ovarian Cancer

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SUMMARY: It is estimated that in the United States, approximately 19,680 women will be diagnosed with ovarian cancer in 2024 and 12,740 women will die of the disease. Ovarian cancer ranks fifth in cancer deaths among women. It accounts for more deaths than any other cancer of the female reproductive system. Approximately 75% of the ovarian cancer patients are diagnosed with advanced disease. Approximately 85% of all ovarian cancers are epithelial in origin, and approximately 70% of all epithelial ovarian cancers are High-Grade Serous adenocarcinomas. Patients with newly diagnosed advanced ovarian cancer are often treated with platinum-based chemotherapy following primary surgical cytoreduction. Approximately 70% of these patients will relapse within the subsequent 3 years and are incurable, with a 5-year Overall Survival rate of about 20-30%.

DNA damage is a common occurrence in daily life by UV light, ionizing radiation, replication errors, chemical agents, etc. This can result in single and double strand breaks in the DNA structure which must be repaired for cell survival. The two vital pathways for DNA repair in a normal cell are BRCA1/BRCA2 and PARP. BRCA1 and BRCA2 are tumor suppressor genes, and they recognize and repair double strand DNA breaks via Homologous Recombination (HR) pathway. Homologous Recombination is a DNA repair pathway utilized by cells to accurately repair DNA double-stranded breaks during the S and G2 phases of the cell cycle, and thereby maintain genomic integrity.

Homologous Recombination Deficiency (HRD) is noted following mutation of genes involved in HR repair pathway. At least 15 genes are involved in the Homologous Recombination Repair (HRR) pathway including BRCA1 and BRCA2 genes. Mutations in BRCA1 and BRCA2 account for about 20-25% of hereditary breast cancers 15% of ovarian cancers, in addition to other cancers such as colon, pancreas and prostate. BRCA mutations can either be inherited (Germline) and present in all individual cells or can be acquired and occur exclusively in the tumor cells (Somatic).

The PARP (Poly ADP Ribose Polymerase) family of enzymes includes PARP1 and PARP2, and is a related enzymatic pathway that repairs single strand breaks in DNA. In a BRCA mutant, the cancer cell relies solely on PARP pathway for DNA repair to survive. PARP inhibitors traps PARP onto DNA at sites of single-strand breaks, thereby preventing their repair and generate double-strand breaks. These breaks cannot be repaired accurately in tumors harboring defects in Homologous Recombination Repair pathway genes, such as BRCA1 or BRCA2 mutations, and this leads to cumulative DNA damage and tumor cell death.

RUBRACA® (Rucaparib) is an oral, small molecule PARP inhibitor, developed for treatment of ovarian cancer associated with Homologous Recombination DNA repair deficiency (HRD). With regards to ovarian cancer, RUBRACA® is presently approved by the FDA for the maintenance treatment of patients with a deleterious BRCA mutation (germline and/or somatic)- associated recurrent epithelial ovarian, fallopian tube, or primary peritoneal cancer, who are in a complete or partial response to platinum-based chemotherapy.

ATHENA is an international, multicenter, randomized, double-blind, placebo-controlled, Phase III trial, which evaluated first-line maintenance treatment for patients with newly diagnosed advanced ovarian cancer. ATHENA was designed to evaluate RUBRACA® first-line maintenance treatment in a broad group of patients, including those WITHOUT BRCA1 or BRCA2 (BRCA) mutations or other evidence of Homologous Recombination Deficiency (HRD), or high-risk clinical characteristics such as residual disease. ATHENA study has two separate and fully independently powered comparisons evaluating RUBRACA® monotherapy (ATHENA-MONO) and RUBRACA® plus Nivolumab (ATHENA-COMBO), as maintenance treatment in this patient population.

In the ATHENA-MONO trial, patients with Stage III-IV high-grade ovarian cancer undergoing surgical cytoreduction (R0/complete resection permitted) and responding to 4-8 cycles of first-line platinum-doublet chemotherapy, were randomly assigned 4:1 to receive RUBRACA® 600 mg orally twice daily (N=427) or placebo (N=111). A total of 234 patients had HRD, of whom 185 received RUBRACA® and 49 received placebo. Treatment was continued for 24 months, or until disease progression or unacceptable toxicity. Patients were stratified by HRD test status, residual disease after chemotherapy, and timing of surgery (primary surgery versus interval debulking). The median age was 61 yrs, majority of the patients (78%) did not have a BRCA mutation. Patients were stratified by HRD classification (BRCA wild-type/LOH (Loss of Heterozygosity) high-16% or more, BRCA wild-type/LOH low-less than 16%, and BRCA wild-type/LOH indeterminate). The Primary end point of investigator-assessed Progression Free Survival (PFS) was assessed in a step-down procedure, first in the HRD population (BRCA-mutant or BRCA wild-type/LOH high tumor), and then in the Intent-To-Treat (ITT) population. Secondary end points included Overall Survival (OS), investigator-assessed Objective Response Rate (ORR) in patients with measurable disease at baseline, and Duration of Response (DOR) for patients with investigator-assessed confirmed radiographic Complete Response (CR) or Partial Response (PR).

At a median follow up of 26 months, RUBRACA® maintenance after chemotherapy and surgery significantly improved PFS, compared to placebo maintenance, among all subgroups in the Intent-to Treat population including BRCA-mutant, BRCA wild-type/LOH high, and BRCA wild-type/LOH low (HRD-negative) groups.

The researchers have now provided long term follow-up analysis (median follow-up of 37.0 months). In the Intent-To-Treat (ITT) population, the median Time to First Subsequent Treatment (TFST) was 23.3 months in the RUBRACA® group and 12.1 months in the placebo group (HR=0.52). In the HRD population, the median TFST was 32.7 months in the RUBRACA® group and 15.1 months in the placebo group (HR=0.50).

In the ITT population, the median PFS2 was 36.0 months and 26.8 months in the RUBRACA® and placebo groups respectively (HR=0.84). In the HRD population, the median PFS2 was Not Reached in the RUBRACA® group and was 39.9 months in the placebo group (HR=0.75).

The researchers noted that the clinical benefit of RUBRACA® extended beyond first progression and beyond the 2-year completion of treatment, suggesting that starting RUBRACA® maintenance in the first-line setting benefitted patients through and following their second-line treatment. Overall Survival (OS) data were not mature at the time of this analysis.

It was concluded that first line maintenance therapy with RUBRACA® in addition to providing Progression Free Survival benefit compared to placebo, was found to prolong both Time to First Subsequent Treatment and second Progression Free Survival, with manageable toxicity, in patients with newly diagnosed ovarian cancer, regardless of Homologous Recombination Deficiency (HRD) or BRCA mutation status.

Interim post-progression data and updated survival in patients with newly diagnosed advanced ovarian cancer in ATHENA-MONO. Kristeleit RS, O’Malley DM, Lim, MC, et al. Presented at the 2024 SGO Annual Meeting on Women’s Cancer; San Diego, CA; March 16-18, 2024.

Omitting Axillary Lymph Node Dissection in Breast Cancer with Sentinel-Node Metastases

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SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. It is estimated that in the US, approximately 310,720 new cases of female breast cancer will be diagnosed in 2024, and about 42,250 individuals will die of the disease, largely due to metastatic recurrence.

Axillary lymph node status is a significant prognostic factor in patients with operable primary breast cancer, and is the most important predictor of recurrence and survival. Axillary lymph node dissection is used for staging of breast cancer and treatment of the axilla, if necessary. It is estimated that approximately 20-25% of women will have positive axillary lymph nodes when their breast cancer is detected through screening, whereas those with symptomatic early breast cancer have a 30-40% chance of having positive axillary nodes.

Axillary lymph node dissection is indicated for patients with proven axillary disease preoperatively or with a positive sentinel node biopsy. However, the landscape of breast cancer management has undergone significant evolution in recent years, particularly regarding the role of axillary surgery in node-negative disease. Among patients with clinically node negative breast cancer and 1-2 sentinel node metastases undergoing breast-conserving surgery and whole-breast radiation therapy, studies have shown that omission of axillary lymph node dissection did not have an impact on Overall Survival. However, questions remained about the necessity of completion axillary lymph node dissection in cases of sentinel-node metastases.

The SENOMAC trial was conducted in a large cohort of patients, to validate results from previous trials by comparing sentinel-node biopsy only with completion axillary lymph node dissection, in patients with clinically node-negative breast cancer and sentinel-lymph-node metastases. This study specifically focused only on patients with sentinel node macrometastases and extended eligibility criteria to include underrepresented subgroups such as those patients undergoing mastectomy, those with sentinel-node extracapsular extension or T3 tumors (tumor size more than 5 cm in the largest dimension), and men, thus broadening its applicability and relevance to real-world clinical scenarios.

In this ongoing, Phase III, international, randomized, non-inferiority trial which included 2540 patients (N=2540) from 5 European countries, 1335 had been assigned to undergo sentinel-node biopsy only with no further axillary surgery and 1205 to undergo completion axillary lymph node dissection (dissection group). Eligible patients had clinically node-negative breast cancer, with a tumor stage of T1, T2, or T3 (tumor size, T1, 2 cm or less; T2, 2-5 cm; and T3, more than 5 cm in greatest dimension) and one or two sentinel-node macrometastases (metastasis size, more than 2 mm in the greatest dimension). Patients who had suspicious but nonpalpable axillary lymph nodes on ultrasonography were eligible even if metastasis was confirmed by fine-needle aspiration. Adjuvant treatments and radiation therapy were administered in accordance with national guidelines, ensuring consistency in the approach to postoperative care across study participants. Whole-breast radiation therapy after breast-conserving surgery was mandatory, and radiation therapy including nodal target volumes was administered to 89.9% in the sentinel node biopsy-only group and to 88.4% in the dissection group. The median patient age was 61 yrs, approximately 64% had breast conserving surgery, 36% had mastectomy and 6% had T3 tumors. The Primary end point was Overall Survival (OS), and prespecified Secondary end points were Recurrence-Free Survival (RFS), Breast Cancer-Specific Survival, and Patient-Reported Outcomes. The median follow-up was 46.8 months.

Results from the trial demonstrated that the omission of completion axillary lymph node dissection was noninferior to the more extensive surgery in terms of Recurrence-Free Survival (RFS), and the estimated 5-year Recurrence-Free Survival was similar in the two treatment groups. The estimated 5-year RFS was 89.7% in the sentinel-node biopsy-only group and 88.7% in the dissection group, with a country-adjusted HR for recurrence or death of 0.89, which was significantly below the prespecified noninferiority margin (P<0.001).

These findings align with previous trials such as ACOSOG Z0011 and AMAROS, which also questioned the necessity of completion axillary lymph node dissection in certain patient populations. Yet, the SENOMAC trial offers distinct contributions. It included patients with T3 tumors and allowed for mastectomy, thus addressing gaps in previous research. Furthermore, the trial enrolled a substantial number of older patients, enhancing the generalizability of its results. Additionally, the trial adds to the growing body of evidence questioning the necessity of axillary surgery in diverse clinical scenarios, particularly in the era of advanced diagnostic imaging and tailored adjuvant therapies.

While the study has limitations, such as variations in radiation therapy practices and the predominantly luminal subtype of breast cancer among enrolled patients, its robust methodology and outcomes provide valuable insights. The results support the notion that axillary surgery may be unnecessary for certain patients with early-stage breast cancer and sentinel-node metastases, especially when combined with appropriate adjuvant therapies.

The researchers concluded that the omission of complete axillary lymph node dissection was noninferior to the more extensive surgery in patients with clinically node-negative breast cancer who had sentinel-node macrometastases, most of whom received nodal radiation therapy. The SENOMAC trial represents a significant milestone in advancing the evidence base and shaping clinical guidelines for the management of early-stage breast cancer with sentinel-node metastases.

Omitting Axillary Dissection in Breast Cancer with Sentinel-Node Metastases. de Boniface J, Tvedskov TF, Rydén L, et al. For the SENOMAC Trialists Group. N Engl J Med 2024;390:1163-1175.

FDA Approves ENHERTU® for Unresectable or Metastatic HER2-Positive Solid Tumors

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SUMMARY: The FDA on April 5, 2024, granted accelerated approval to ENHERTU® (fam-Trastuzumab Deruxtecan-nxki) for adult patients with unresectable or metastatic HER2-positive (IHC3+) solid tumors who have received prior systemic treatment, and have no satisfactory alternative treatment options. This tumor agnostic indication was approved based on Objective Response Rate and Duration of Response.

The HER or erbB family of receptors consist of HER1, HER2, HER3 and HER4. HER2 is a Tyrosine Kinase Receptor growth-promoting protein and is involved in normal cell growth. It is expressed on the surface of various tissue cells throughout the body. In some cancers, HER2 expression is amplified or the cells have activating mutations. HER2 gene amplification can result in HER2 protein overexpression which is often associated with aggressive disease and poor prognosis. Approximately 15-20% of invasive breast cancers as well as advanced Gastric and GastroEsophageal (GE) junction cancers overexpress or have amplification of the HER2 oncogene. These patients often receive first line treatment with a combination of chemotherapy plus anti-HER2 antibody. Additionally, HER2 directed therapies have been used to treat lung and colorectal cancers. HER2 is an emerging biomarker in other solid tumor types including biliary tract, bladder, cervical, endometrial, ovarian and pancreatic cancers with HER2 positive expression rates varying from 1-28%. There are currently no approved HER2 directed therapies for these cancers following progression on standard of care therapies. There is an unmet need for effective therapies for these HER2 expressing tumor types.

ENHERTU® (Trastuzumab Deruxtecan) is an Antibody-Drug Conjugate (ADC) composed of a humanized monoclonal antibody specifically targeting HER2, with the amino acid sequence similar to Trastuzumab, a cleavable tetrapeptide-based linker, and a potent cytotoxic Topoisomerase I inhibitor as the cytotoxic drug (payload). ENHERTU® has a favorable pharmacokinetic profile and the tetrapeptide-based linker is stable in the plasma and is selectively cleaved by cathepsins that are up-regulated in tumor cells. Unlike KADCYLA® (ado-Trastuzumab emtansine), another ADC targeting HER2, ENHERTU® has a higher drug-to-antibody ratio (8 versus 4), released payload easily crosses the cell membrane with resulting potent cytotoxic effect on neighboring tumor cells regardless of target expression, and the released cytotoxic agent (payload) has a short half-life, thus minimizing systemic exposure.

The FDA approval was based on the efficacy of ENHERTU® in 192 adult patients with previously treated unresectable or metastatic HER2-positive (IHC 3+) solid tumors who were enrolled in one of three multicenter trials: DESTINY-PanTumor02 (NCT04482309), DESTINY-Lung01 (NCT03505710), and DESTINY-CRC02 (NCT04744831). All three trials excluded patients with a history of Interstitial Lung Disease /pneumonitis requiring treatment with steroids or Interstitial Lung Disease /pneumonitis at screening and clinically significant cardiac disease. Patients were also excluded for active brain metastases or ECOG performance status more than 1. Treatment was administered until disease progression or unacceptable toxicity. The major efficacy outcome measure in all three trials was confirmed Objective Response Rate (ORR), and an additional efficacy outcome was Duration of Response (DOR). All outcomes were assessed by Independent Central Review based on RECIST criteria.

DESTINY-PanTumor02 is a global, multicenter, multi-cohort, open-label, ongoing Phase II trial evaluating the efficacy and safety of ENHERTU® 5.4 mg/kg IV for the treatment of previously treated HER2 expressing tumors, including biliary tract, bladder, cervical, endometrial, ovarian, pancreatic cancer or other tumors. DESTINY-PanTumor02 enrolled 267 patients (N=267) at multiple sites in Asia, Europe and North America. Patients had received a median of two prior cancer therapies. In this study, the ORR was 51.4% and median DOR was 19.4 months.

DESTINY-Lung01 is a global, open-label, two-cohort, Phase II trial evaluating the efficacy and safety of ENHERTU® 6.4 mg/kg IV and 5.4 mg/kg IV in patients with HER2 mutant (cohort 2, N=91) or HER2 overexpressing (cohort 1 and 1a, N=90) (defined as IHC 3+ or IHC 2+) unresectable or metastatic non-squamous Non-Small Cell Lung Cancer (NSCLC), who had progressed after one or more systemic therapies. In this study, the ORR was 52.9% and the median DOR was 6.9 months.

DESTINY-CRC02 is a global, randomized, two arm, parallel, multicenter Phase II trial evaluating the efficacy and safety of two doses, 5.4 mg/kg IV or 6.4 mg/kg IV of ENHERTU® in patients with locally advanced, unresectable or metastatic HER2 positive colorectal cancer of BRAF wild-type, or RAS wild-type and RAS mutant tumor types, previously treated with standard therapy. The trial was conducted in two stages. In the first stage, patients (N=80) were randomized 1:1 to receive either 5.4 mg/kg IV or 6.4 mg/kg IV of ENHERTU®. In the second stage, additional patients (N=42) were enrolled in the 5.4 mg/kg IV arm. In DESTINY-CRC02, ORR was 46.9%, and DOR was 5.5 months.

The most common adverse reactions were cytopenias, nausea, vomiting, fatigue, liver function abnormalities and upper respiratory tract infection. The recommended dose of ENHERTU® for this indication is 5.4 mg/kg IV every 3 weeks until disease progression or unacceptable toxicity.

The forementioned trials validate HER2 as an actionable biomarker across a broad range of tumor types, and ENHERTU® has the potential to benefit patients with HER2 expressing advanced disease, who may face a poor prognosis and currently have limited treatment options.

https://www.fda.gov/drugs/resources-information-approved-drugs/fda-grants-accelerated-approval-fam-trastuzumab-deruxtecan-nxki-unresectable-or-metastatic-her2.

April 2024: Current Tumor-Agnostic Therapies

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The FDA on April 5, 2024, granted accelerated approval to Fam-trastuzumab deruxtecan-nxki (ENHERTU®) for adult patients with unresectable or metastatic HER2-positive (IHC3+) solid tumors who have received prior systemic treatment and have no satisfactory alternative treatment options.

This is the 6th Tumor-Agnostic therapeutic target for which an agent has received regulatory agency approval.

A current summary of the Tumor-Agnostic therapeutic targets, and agents approved, is provided below. Please review the drug Prescribing Information for the respective therapeutic agents, as NOT all products are approved for First Line therapy.

MMRd/MSI-H: Pembrolizumab (KEYTRUDA®) and Dostarlimab (JEMPERLI®)
TMB-H: Pembrolizumab (KEYTRUDA®)
NTRK fusions: Larotrectinib (VITRAKVI) and Entrectinib (ROZLYTREK®)
BRAF V600E: Dabrafenib (TAFINLAR®) plus Trametinib (MEKINIST®)
RET Fusions: Selpercatinib (RETEVMO®)
HER2 Overexpression: Fam-trastuzumab deruxtecan (ENHERTU®)

The National Cancer Institute describes Tumor-Agnostic therapy as a type of targeted treatment that uses drugs or other substances to treat cancer based on the cancer’s genetic and molecular features, without regard to the cancer type or where the cancer started in the body. Tissue-Agnostic therapy uses the same drug to treat all cancer types that have the genetic mutation or biomarker, that is targeted by the drug.

Enfortumab Vedotin plus Pembrolizumab: A Breakthrough in Locally Advanced or Metastatic Urothelial Carcinoma

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SUMMARY: The American Cancer Society estimates that in the United States for 2024, about 83,190 new cases of bladder cancer will be diagnosed and approximately 16,840 patients will die of the disease. Bladder cancer is the fourth most common cancer in men, but it is less common in women. Bladder cancer accounts for 90% of urothelial cancers, and urothelial cancer can also be found in the renal pelvis, ureter and urethra. Approximately 12% of urothelial cancer cases at diagnosis are locally advanced or metastatic.

Patients with urothelial carcinoma are currently treated in the first line setting with a Platinum based chemotherapy regimen, and a checkpoint Inhibitor (PD-1 or PD-L1 inhibitor) in the second line setting. However, approximately 50% of patients with advanced urothelial carcinoma are ineligible for Cisplatin-based chemotherapy due to toxicities, and responses are rarely durable. There is therefore a critical need for effective and tolerable first line treatment options in locally advanced or metastatic urothelial carcinoma.

Enfortumab vedotin-ejfv (PADCEV®) is a first-in-class Antibody-Drug Conjugate (ADC) that targets Nectin-4, a cell adhesion molecule highly expressed in urothelial cancers and other solid tumors. Nectin-4 has been implicated in tumor cell growth and proliferation. Following binding to Nectin-4 on the cell surface, Enfortumab vedotin becomes internalized and is processed by lysosomes, with the liberation of its cytotoxic payload, MonoMethyl Auristatin E (MMAE), which in turn disrupts microtubule assembly, leading to cell cycle arrest and apoptosis. Enfortumab vedotin resulted in significantly longer Overall Survival, Progression Free Survival, and a higher Overall Response Rate, than standard chemotherapy, in patients with locally advanced or metastatic urothelial carcinoma, who had previously received Platinum-based treatment and a PD-1 or PD-L1 inhibitor. Preclinical studies with Enfortumab vedotin have shown hallmarks of immune cell death potentially augmented by PD-1/PD-L1 inhibitors, and the rationale for this clinical trial was based on results from a previous cohort study.

Pembrolizumab (KEYTRUDA®) is a fully humanized, Immunoglobulin G4, anti-PD-1, monoclonal antibody, that binds to the PD-1 receptor and blocks its interaction with ligands PD-L1 and PD-L2. By doing so, it unleashes the tumor-specific effector T cells, and is thereby able to undo PD-1 pathway-mediated inhibition of the immune response. Pembrolizumab is the first agent to improve Overall Survival over chemotherapy, in the second line setting, for patients with recurrent, advanced urothelial carcinoma, and a significant proportion of patients who respond, have very durable responses.

EV-302 is a landmark Phase III, global, open-label, randomized trial comparing the efficacy and safety of Enfortumab vedotin and Pembrolizumab with the efficacy and safety of platinum-based chemotherapy, in patients with previously untreated locally advanced or metastatic urothelial carcinoma. A total of 886 eligible patients were randomly assigned in a 1:1 ratio to receive 3-week cycles of Enfortumab vedotin 1.25 mg/kg IV on days 1 and 8 and Pembrolizumab 200 mg IV on day 1 of every 3-week cycle (N=442) or chemotherapy consisting of Gemcitabine and either Cisplatin or Carboplatin (N=444), determined on the basis of eligibility to receive cisplatin, for a maximum of 6 cycles. The maximum number of Pembrolizumab cycles allowed was 35 and there was no maximum number of cycles set for Enfortumab vedotin. The treatment groups were well balanced. The median age was 69 yrs and randomization was stratified according to eligibility to receive Cisplatin (eligible or ineligible), PD-L1 expression status (High-CPS 10 or more versus Low-CPS less than 10), and liver metastases (present or absent). The co-Primary end points were Progression Free Survival (PFS) and Overall Survival (OS) as assessed by Blinded Independent Central Review (BICR). Secondary end points included Overall Response Rate (ORR) as assessed by BICR, Duration of Response, and Safety. As of the data cutoff date, the median duration of follow-up for survival was 17.2 months.

The PFS was significantly longer in the Enfortumab vedotin plus Pembrolizumab group compared to the chemotherapy group (median duration 12.5 months versus 6.3 months; HR=0.45; P<0.001), representing a 55% reduction in the risk of disease progression or death. Enfortumab vedotin plus Pembrolizumab also substantially improved median OS, and the median OS was 31.5 months compared to 16.1 months with chemotherapy (HR=0.47; P<0.001) representing a 53% reduction in the risk of death. These PFS and OS benefits were consistent between the intention-to-treat population and all the prespecified subgroups, including those defined according to Cisplatin eligibility status and PD-L1 expression status. The Overall Response Rate (ORR) in the Enfortumab vedotin plus Pembrolizumab group was 67.7%, significantly higher than the 44.4% ORR observed with chemotherapy alone (P<0.001), with a Complete Response rate of 29.1% versus 12.5% respectively. The median Duration of Response was Not Reached in the Enfortumab vedotin plus Pembrolizumab group and was 7.0 months in the chemotherapy group.

Treatment-related adverse events of Grade 3 or higher occurred in 55.9% of the patients in the Enfortumab vedotin plus Pembrolizumab group, and was 69.5% in the chemotherapy group. The most common treatment-related adverse events of any grade in the Enfortumab vedotin plus Pembrolizumab group were peripheral sensory neuropathy, pruritus and alopecia, whereas the most common such events in the chemotherapy group were anemia, neutropenia and nausea.

It was concluded that treatment with Enfortumab vedotin plus Pembrolizumab resulted in significantly better outcomes than chemotherapy in patients with untreated locally advanced or metastatic urothelial carcinoma, emerging as a potential new standard of care, irrespective of Cisplatin eligibility. The results from this study mark a significant paradigm shift in the management of locally advanced or metastatic urothelial carcinoma, offering new hope for patients and clinicians alike.

Enfortumab Vedotin and Pembrolizumab in Untreated Advanced Urothelial Cancer. Powles T, Valderrama BP, Gupta S, et al. for the EV-302 Trial Investigators. N Engl J Med 2024;390:875-888.

Novel Prognostic Factors for Treatment-Free Remission in Chronic Myeloid leukemia

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SUMMARY: Chronic Myeloid Leukemia (CML) constitutes about 15% of all new cases of leukemia. The American Cancer Society estimates that about 9,280 new CML cases will be diagnosed in the United States in 2024 and about 1,280 patients will die of the disease. The hallmark of CML, the Philadelphia Chromosome (Chromosome 22), is a result of a reciprocal translocation between chromosomes 9 and 22, wherein the ABL gene from chromosome 9 fuses with the BCR gene on chromosome 22. As a result, the auto inhibitory function of the ABL gene is lost and the BCR-ABL fusion gene is activated resulting in cell proliferation and leukemic transformation of hematopoietic stem cells.

Chronic Myeloid Leukemia has long been a model for targeted cancer therapy, particularly through the development of Tyrosine Kinase Inhibitors (TKIs) targeting the BCR:ABL1 fusion gene. The presently available Tyrosine Kinase Inhibitors (TKI’s) approved in the United States including Imatinib, share the same therapeutic target, which is BCR-ABL kinase. Resistance to TKI’s can occur as a result of mutations in the BCR-ABL kinase domain or amplification of the BCR-ABL gene. With the availability of newer therapies for CML, monitoring response to treatment is important. This is best accomplished by measuring the amount of residual disease using Reverse Transcription-Polymerase Chain Reaction (RT-PCR). Molecular response in CML is expressed using the International Scale (IS) as BCR-ABL%, which is the ratio between BCR-ABL and a control gene. BCR-ABL kinase domain point mutations are detected using the mutational analysis by Sanger sequencing. Majority of the patients receiving a TKI following diagnosis of CML achieve a Complete Cytogenetic Response (CCyR) within 12 months following commencement of therapy and these patients have a life expectancy similar to that of their healthy counterparts. Previously published studies have shown that Deep Molecular Response (BCR-ABL <0.01% on the International Scale-MR4) is a new molecular predictor of long term survival in CML patients, and this was achieved in a majority of patients treated with TKIs. Further, it has been shown from previous observations, that a subgroup of CML patients experiencing deeper responses (MR3, MR4, and MR4.5), may stay in unmaintained remission even after treatment discontinuation. Despite this observation, precise criteria for stopping CML therapy have not been clearly defined.

Discontinuing TKI therapy after a Deep Molecular Response among patients with CML can potentially improve quality of life, minimize long term toxicities as well as drug-drug interactions, and reduce financial burden. Stopping TKI therapy among CML patients appears to be safe and feasible in over 50% of the patients, although about 20% of these patients experience TKI withdrawal syndrome manifesting as musculoskeletal symptoms. Discontinuation of TKI therapy should only be considered in consenting patients after a thorough discussion of the potential risks and benefits. TKIs have revolutionized the prognosis and quality of life for patients with CML, leading to a new treatment goal of achieving Treatment-Free Remission (TFR).

The European Stop Kinase Inhibitors (EURO-SKI) study is the largest clinical trial conducted to assess the safety of stopping Tyrosine Kinase Inhibitor therapy in patients with CML, whose leukemia was in stable Deep Molecular Response (DMR). The researchers presented the final analysis of the EURO-SKI trial after 3 years of follow up and highlighted the prognostic factors for short- and long-term molecular response maintenance. This comprehensive study evaluated the effects of stopping TKI treatment (Imatinib, Nilotinib or Dasatinib), in patients who had been on therapy for at least 3 years and had confirmed DMR, defined as BCR:ABL1-transcripts 0.01% or less on the International Scale for at least 12 months. The Primary outcomes of the study were the maintenance of Major Molecular Response (MMR), defined as BCR:ABL1 0.1% or less (MR3), at 6 and 36 months after stopping TKIs (Molecular Recurrence Free Survival).

In this study, 868 patients with Chronic Phase CML were screened, and 728 patients were included in the baseline analysis. The final analysis revealed that 61% of patients remained in MMR at 6 months, and 46% remained in MMR at 36 months after stopping TKI treatment. Several factors were identified as significant predictors of MMR maintenance. Longer duration of TKI treatment and DMR before stopping TKI treatment were associated with a higher likelihood of maintaining MMR at 6 months. Additionally, the type of BCR:ABL1 transcript emerged as a prognostic factor, with patients having transcript type e14a2 alone or in combination with e13a2 showing a significantly higher probability of maintaining MMR. For MMR maintenance between 6 and 36 months, the duration of TKI treatment (but not DMR duration) before stopping TKI treatment, and disease characteristics at diagnosis, including percentage of peripheral blood blast cells and platelet count at diagnosis, were significant factors influencing MMR maintenance. Among 315 patients evaluated at 36 months, the Molecular Recurrence Free Survival was 76%. Multivariate analysis over the entire 36-month trial period identified duration of TKI treatment, duration of DMR (Deep Molecular Response) while receiving TKI, percentage of peripheral blood blast cells at diagnosis, and transcript type (e14a2 plus e13a2 had a higher probability of maintaining MMR over 36 months than e13a2 alone) as independent factors for MMR maintenance.

The findings of the EURO-SKI trial have important implications and represent a significant milestone for the management of CML. They highlight the importance of considering not only the duration of TKI treatment but also disease characteristics and transcript type when predicting treatment-free remission. This study represents a significant step forward in understanding the factors influencing Treatment-Free Remission in CML patients, and may help guide clinical decision-making in the future.

European Stop Tyrosine Kinase Inhibitor Trial (EURO-SKI) in Chronic Myeloid Leukemia: Final Analysis and Novel Prognostic Factors for Treatment-Free Remission. Mahon F-X, Pfirrmann M, Dulucq S, et al. on behalf of the EURO-SKI Investigators. Journal of Clinical Oncology. March 12, 2024. https://doi.org/10.1200/JCO.23.01647.

Neoadjuvant KEYTRUDA® plus Chemotherapy Significantly Improves EFS in Early Stage High Risk Triple Negative Breast Cancer

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SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. The American Cancer Society estimates that in the US, approximately 310,720 new cases of female breast cancer will be diagnosed in 2024, and about 42,250 individuals will die of the disease, largely due to metastatic recurrence.

Triple Negative Breast Cancer (TNBC) is a heterogeneous, molecularly diverse group of breast cancers and are ER (Estrogen Receptor), PR (Progesterone Receptor) and HER2 (Human Epidermal Growth Factor Receptor-2) negative. TNBC accounts for 15-20% of invasive breast cancers, with a higher incidence noted in young patients. It is usually aggressive, and tumors tend to be high grade and patients with TNBC are at a higher risk of both local and distant recurrence. Those with metastatic disease have one of the worst prognoses of all cancers with a median Overall Survival (OS) of 13 months. The majority of patients with TNBC who develop metastatic disease do so within the first 3 years after diagnosis, whereas those without recurrence during this period of time have survival rates similar to those with ER-positive breast cancers.

Neoadjuvant chemotherapy is the preferred treatment approach in this group of patients and can potentially increase the likelihood of tumor resectability and breast conservation. Further, a pathological Complete Response (pCR) after neoadjuvant chemotherapy can result in a longer Event-Free Survival and Overall Survival. Pathological Complete Response is therefore used as an end point for clinical testing of neoadjuvant treatment in patients with early triple-negative breast cancer.

KEYTRUDA® (Pembrolizumab) is a fully humanized, Immunoglobulin G4, anti-PD-1, monoclonal antibody, that binds to the PD-1 receptor and blocks its interaction with ligands PD-L1 and PD-L2. It thereby reverses the PD-1 pathway-mediated inhibition of the immune response, and unleashes the tumor-specific effector T cells. The rationale for combining chemotherapy with immunotherapy is that cytotoxic chemotherapy releases tumor-specific antigens, and immune checkpoint inhibitors such as Pembrolizumab when given along with chemotherapy can enhance endogenous anticancer immunity. Single agent Pembrolizumab in metastatic TNBC demonstrated durable antitumor activity in several studies, with Objective Response Rates (ORRs) ranging from 10-21% and improved clinical responses in patients with higher PD-L1 expression. When given along with chemotherapy as a neoadjuvant treatment for patients with high-risk, early-stage TNBC, Pembrolizumab combination achieved pathological Complete Response rate of 65%, regardless of PD-L1 expression.

KEYNOTE-522 trial is a multicenter, randomized, double-blind, placebo-controlled Phase III trial, conducted to evaluate the efficacy and safety of neoadjuvant Pembrolizumab plus chemotherapy as compared with neoadjuvant placebo plus chemotherapy, followed by adjuvant Pembrolizumab or placebo in patients with early stage, high-risk, Triple Negative Breast Cancer. In this study, total of 1174 patients (N=1174) regardless of tumor PD⁠-⁠L1 expression, were randomly assigned 2:1 to receive Pembrolizumab plus chemotherapy (N=784) or placebo plus chemotherapy (N=390). Eligible patients had newly diagnosed, previously untreated, Triple Negative Breast Cancer, with tumor size more than 1 cm but 2 cm or less in diameter with nodal involvement, or tumor size more than 2 cm in diameter regardless of nodal involvement. Patients in the neoadjuvant phase received four cycles of Pembrolizumab 200 mg IV or placebo once every 3 weeks plus Paclitaxel 80 mg/m2 once weekly plus Carboplatin AUC 5 IV once every 3 weeks or Carboplatin AUC 1.5 IV once weekly in the first 12 weeks (first neoadjuvant treatment), followed by four cycles of Pembrolizumab or placebo along with Doxorubicin 60 mg/m2 IV or Epirubicin 90 mg/m2 IV plus Cyclophosphamide 600 mg/m2 IV once every 3 weeks in the subsequent 12 weeks (second neoadjuvant treatment). Patients then underwent definitive surgery (breast conservation or mastectomy with sentinel lymph-node evaluation or axillary dissection) 3-6 weeks after the last cycle of the neoadjuvant phase. In the adjuvant phase, patients received radiation therapy as indicated and Pembrolizumab or placebo once every 3 weeks for up to nine cycles. Adjuvant Capecitabine was not allowed. The median age was 49 yrs, 64% were white, 56% were premenopausal, and overall 75% had Stage II disease and 25% had Stage III disease. Both treatment groups were well balanced with regard to age, ECOG performance status, PD-L1-positivity, tumor size and nodal involvement. The Primary end points were a pathological Complete Response (pCR) at the time of definitive surgery and Event-Free Survival (EFS) in the intent-to-treat population. Pathological Complete Response was defined as absence of invasive cancer in the breast and lymph nodes (ypT0/Tis ypN0), and was assessed by the blinded local pathologist at the time of definitive surgery. EFS was defined as the time from randomization to the first occurrence of progression of disease that precludes definitive surgery, local or distant recurrence, second primary malignancy, or death due to any cause.

The pathological Complete Response rate was 63% in the Pembrolizumab plus chemotherapy group and 55.6% in the placebo plus chemotherapy group, and this difference were statistically significant. The EFS after median follow up of 63.1 months showed a 5-year EFS rate of 81.3% with Pembrolizumab plus chemotherapy and 72.3% with placebo plus chemotherapy (HR=0.63). The median EFS had not been reached in either group. The EFS benefit appeared consistent across subgroups, including those assessed by nodal status, disease stage, PD-L1 expression, menopausal status and Carboplatin schedule. A prespecified, exploratory analysis showed higher 5-year EFS rates with Pembrolizumab among patients who achieved pathologic Complete Response (92.2% versus 88.2%) and among those who did not achieve pathologic Complete Response (62.6% versus 52.3%).

It was concluded that the addition of Pembrolizumab with neoadjuvant chemotherapy followed by Pembrolizumab monotherapy in the adjuvant setting resulted in a durable Event Free Survival benefit, for patients with early stage Triple Negative Breast Cancer, and this benefit was noted across key subgroups, as well as among patients who did or did not achieve pathologic Complete Response.

Neoadjuvant pembrolizumab or placebo plus chemotherapy followed by adjuvant pembrolizumab or placebo for early-stage triple-negative breast cancer: updated event-free survival results from the phase 3 KEYNOTE-522 study. Schmid P, Cortés J, Dent R, et al. Presented at the 2023 San Antonio Breast Cancer Symposium; December 5-9, 2023; San Antonio, TX; abstract LBO1-01.