FDA Approves ENHERTU® for Advanced HER2-Positive Breast Cancer

SUMMARY: The FDA on December 20, 2019, granted accelerated approval to ENHERTU® (Trastuzumab deruxtecan) for patients with unresectable or metastatic HER2-positive breast cancer, who have received two or more prior anti-HER2-based regimens in the metastatic setting. 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. Approximately 268,600 new cases of invasive breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. The HER or erbB family of receptors consist of HER1, HER2, HER3 and HER4. Approximately 15-20% of invasive breast cancers overexpress HER2/neu oncogene, which is a negative predictor of outcomes without systemic therapy. Patients with HER2-positive metastatic breast cancer are often treated with anti-HER2 targeted therapy along with chemotherapy, irrespective of hormone receptor status, and this has resulted in significantly improved treatment outcomes. HER2-targeted therapies include HERCEPTIN® (Trastuzumab), TYKERB® (Lapatinib), PERJETA® (Pertuzumab) and KADCYLA® (ado-Trastuzumab emtansine). Dual HER2 blockade with HERCEPTIN® and PERJETA®, given along with chemotherapy (with or without endocrine therapy), as first line treatment, in HER2 positive metastatic breast cancer patients, was shown to significantly improve Progression Free Survival (PFS) as well as Overall Survival (OS). The superior benefit with dual HER2 blockade has been attributed to differing mechanisms of action and synergistic interaction between HER2 targeted therapies. Patients progressing on Dual HER2 blockade often receive KADCYLA® which results in an Objective Response Rate (ORR) of 44% and a median PFS of 9.6 months, when administered after HERCEPTIN® and a taxane. There is however no standard treatment option for this patient population following progression on KADCYLA®.Mechanism-of-Action - ENHERTU

ENHERTU® 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®, 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, minimizing systemic exposure. In a Phase 1 dose-finding study involving patients with advanced HER2-positive breast cancer, treatment with ENHERTU® resulted in a confirmed response rate was 59.5%, and the median response duration was 20.7 months. However, the efficacy of ENHERTU® in patients with HER2-positive metastatic breast cancer, previously treated with KADCYLA® remained unclear.

The present FDA approval was based on DESTINY-Breast01 study, which is a multicenter, single-arm, Phase II trial, in which 184 patients with HER2-positive, metastatic breast cancer, who had received two or more prior HER2 targeted therapies including KADCYLA®, were enrolled. Patients received ENHERTU® 5.4 mg/kg IV every 3 weeks until disease progression or unacceptable toxicity. The median age was 55 years, 53% had Hormone Receptor-positive tumors and the median number of previous lines of therapy for metastatic disease was six and included KADCYLA® (100%), Trastuzumab (100%), Pertuzumab (66%), and other anti-HER2 therapies (54%). The Primary end point was Objective Response Rate (ORR) assessed by Independent Central Review and Secondary endpoints included Duration of Response, Progression Free Survival (PFS) and Overall Survival (OS). The median follow up was 11.1 months. The ORR was 60.9%, with 6% Complete Responses and 54.9% Partial Responses. The median time to response was 1.6 months and the median response duration was 14.8 months. The median PFS was 16.4 months the median OS was not reached at the time of this publication. The most Grade 3 or higher adverse events were cytopenias, nausea, diarrhea and Interstitial Lung Disease.

It was concluded that ENHERTU® has a high level of clinical efficacy with a durable antitumor activity in a pretreated patient population with HER2-positive metastatic breast cancer. Trastuzumab Deruxtecan in Previously Treated HER2-Positive Breast Cancer. Modi S, Saura C, Yamashita T, et al. for the DESTINY-Breast01 Investigators. N Engl J Med. 2019 Dec 11. doi: 10.1056/NEJMoa1914510. [Epub ahead of print]

Long-Term Breast Cancer Preventive Benefit with ARIMIDEX®

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. Approximately 268,600 new cases of invasive breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. Some high risk factors for the development of breast cancer include first-degree relative with breast cancer at any age, first-degree relative with bilateral breast cancer who developed the first breast cancer at 50 years of age or less, Lobular Carcinoma In Situ (LCIS), Atypical ductal or lobular hyperplasia in a benign lesion, and Ductal Carcinoma In-Situ (DCIS).

Previously published studies have shown a 38% reduction in all breast cancers and 50% reduction of ER-positive tumors with the use of SERMs (Selective Estrogen Receptor Modulators) such as Tamoxifen and Raloxifene for breast cancer prevention. Further it has been shown that the effects of Tamoxifen continue with a constant 29% annual preventive effect for at least 15 years after completion of treatment. A further improvement in breast cancer incidence short-term was seen in two trials using, two Aromatase Inhibitors, ARIMIDEX® (Anastrozole) in the International Breast Cancer Intervention Study II (IBIS-II) and AROMASIN® (Exemestane) in the MAP.3 trial. However in the MAP.3 study, the study was unblinded after the initial publication and a post-treatment effect, as was seen with Tamoxifen, was not possible.

The International Breast Cancer Intervention Study II (IBIS-II) is an international, randomized, double-blind, placebo-controlled trial, which was initiated in 2003. In this trial, 3864 postmenopausal women aged 40-70 years, at increased risk of developing breast cancer were recruited and were randomly assigned (1:1) to either ARIMIDEX® 1 mg orally daily (N=1920) or matching placebo (N=1944) daily for 5 years. After treatment completion, women were followed on a yearly basis and data was collected on breast cancer incidence, death, incidence of other cancers, and major adverse events (cardiovascular events and fractures). The median age at study entry was 59 years. The exclusion criteria for this study included premenopausal status, prior breast cancer including Ductal Carcinoma In Situ (DCIS) diagnosed more than 6 months before trial entry, current or previous Tamoxifen, Raloxifene, or other SERM use for more than 6 months, or previous or planned prophylactic mastectomy. Unblinding was only permitted if the participant developed breast cancer, when a clinician considered there to be valid medical or safety reasons. The Primary outcome was the development of histologically confirmed breast cancer, either invasive or non-invasive (DCIS), particularly during the post-5-year time period. Secondary outcomes were ER-positive breast cancer, breast cancer mortality, incidence of other cancers, cardiovascular disease, fractures, and all-cause mortality. The decision to analyze the data was made without looking at the results before hand. The first analysis after a median follow-up of 60 months showed a significant reduction (53%) in incidence for all breast cancer (including DCIS). The authors now report the results on the extended duration of benefit of ARIMIDEX® in preventing breast cancer, for up to 12 years after trial entry.

After a median follow up of 10.9 years for this analysis, women assigned to the ARIMIDEX® group were 49% less likely to develop breast cancer than women assigned to the placebo arm of the study ((HR=0.51, P<0.0001). The reduction in incidence in the first 5 years of follow up was 61% (HR=0.39; P<0.0001), and a smaller but still significant 36% reduction (HR=0.64; P=0•014) was seen in subsequent years, which was still larger than that seen for Tamoxifen in previous trials, and the effects in the two time periods was not significantly different (P=0.08). Invasive ER-positive breast cancer was reduced by 54% with ARIMIDEX® treatment (HR=0.46; P<0.0001), with a continued significant effect observed in the post-treatment follow up period. A 59% reduction in DCIS overall was observed (HR=0.41; P=0.0081), with a very large reduction noted in those cases known to be ER-positive (HR = 0.22; P<0.0001). A significant decrease in non-breast cancers was observed in the ARIMIDEX® group, primarily contributed by non-melanoma skin cancer (P=0.0042), and no excess rates of fractures or cardiovascular disease was observed.

The authors concluded that this updated analysis shows a continuing long-term effect of 5 years of ARIMIDEX® treatment, in preventing breast cancer, in high-risk postmenopausal women. These new results strongly suggest that ARIMIDEX® should be preferred therapy for breast cancer prevention in postmenopausal women at increased risk for the disease, with Tamoxifen used for women who experience severe side effects from ARIMIDEX®. Use of anastrozole for breast cancer prevention (IBIS-II): long-term results of a randomised controlled trial. Cuzick J, Sestak I, Forbes JF, et al. The Lancet. Published:December 12, 2019. DOI:https://doi.org/10.1016/S0140-6736(19)32955-1

Supplemental MRI Screening for Women with Extremely Dense Breast Tissue

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. Approximately 268,600 new cases of invasive breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. Screening mammography complemented by breast self exam and clinical breast exam has resulted in early detection of breast cancer and successful outcomes. Even though mammography is a sensitive screening test, a small percentage of breast cancers may not show up on mammograms but may be palpable on examination by the patient or the clinician. Further, mammograms are less likely to find breast tumors in younger women with dense breast tissue. A breast Magnetic Resonance Imaging (MRI) is more sensitive than mammography although the specificity of a breast MRI is lower, resulting in a higher rate of false-positive findings and potentially unnecessary biopsies. Microcalcifications in the breast can be missed by a breast MRI. Taking these factors into consideration, appropriate utilization of breast MRI becomes relevant.

The American Cancer Society (ACS) recommends an annual MRI as an adjunct to screening mammogram and clinical breast exam in certain groups with increased risk of breast cancer. In a study published by Stout NK, et al., (JAMA Intern Med. 2014;174:114-121), it was noted that breast MRI was over utilized in those who did not fit the ACS criteria and was under utilized in those with documented genetic mutations. Routine breast MRI screening is not recommended for a new breast cancer diagnosis or for breast cancer surveillance and should only be considered for the group of individuals who have the most benefit. Breast MRI is performed preferably between days 7-15 of menstrual cycle for premenopausal women, using a dedicated breast coil, with the ability to perform a biopsy under MRI guidance by experienced radiologists, during the same visit.

DENSE trial is a multicenter, randomized, controlled study which evaluated the effect of supplemental Magnetic Resonance Imaging (MRI) on the incidence of interval cancers, in women with extremely dense breast tissue. In this trial, 40,373 women between the ages of 50 and 75 years with extremely dense breast tissue and normal results on screening mammography were randomly assigned in a 1:4 ratio to a group that was invited to undergo supplemental MRI (N=8061) or to a group that received mammography screening alone (N=32,312). Of the women who were invited to undergo MRI, 59% accepted the invitation (N=4783). All MRI examinations were performed with the use of a dedicated bilateral breast coil. The Primary endpoint was the difference in the incidence of interval cancers during a 2-year screening period, between the mammography screening-only group and MRI-invitation group. Secondary endpoints included the recall rate for additional examination, the cancer-detection rate on MRI, the false positive rate, the positive predictive value, and tumor characteristics.

The interval cancer rate was 2.5 per 1000 screenings in the MRI-invitation group and 5.0 per 1000 screenings in the mammography-only group (P<0.001). The MRI cancer-detection rate among the women who actually underwent MRI screening was 16.5 per 1000 screenings. The Positive Predictive Value of a positive MRI result was 17.4%, the Positive Predictive Value of an indication for biopsy was 23.9% and the Positive Predictive Value of a biopsy was 26.3%. The false positive rate was 79.8 per 1000 screenings. As a result of the MRI screening, 300 women underwent a breast biopsy and of these women, breast cancer was diagnosed in 79 women, of whom 64 had invasive breast cancer and 15 were diagnosed with DCIS.

The authors concluded that the use of supplemental MRI screening in women with extremely dense breast tissue and normal results on mammography resulted in the diagnosis of significantly fewer interval cancers than mammography alone, during a 2-year screening period. Whether a reduction in interval cancers is an appropriate surrogate for improved Overall Survival, remains unclear. Supplemental MRI Screening for Women with Extremely Dense Breast Tissue. Bakker MF, de Lange SV, Pijnappel RM, et al. for the DENSE Trial Study Group. N Engl J Med 2019; 381:2091-2102

Early Adjuvant Chemotherapy Dose Reductions Can Impact Breast Cancer Survival

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. Approximately 268,600 new cases of invasive breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. Patients with early stage breast cancer often receive adjuvant chemotherapy and this is even more so true for HER positive and triple negative (ER, PR and HER negative) breast cancer patients, who are at an increased risk to develop recurrent disease. Meta-analyses conducted by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) has shown a 20-25% relative risk reduction in breast cancer mortality with first-generation adjuvant chemotherapy regimens such as CMF (Cyclophosphamide/Methotrexate/Fluorouracil) and additional survival benefit with the Anthracyclines and Taxane based regimens.

Chemotherapy dose reductions are often considered for patients with obesity, BSA of more than 2.0 m2, age over 65 years, comorbidities such as kidney disease or diabetes, and febrile neutropenia. ASCO guidelines recommend full weight-based chemotherapy doses in the treatment of obese patients. Dose reductions to less than 85% of the optimal (total cumulative) chemotherapy dose (mg/m2) and cycle delay have shown inferior survival outcomes in both prospective and some retrospective studies. However, it is unclear if dose reductions made for third-generation Anthracycline/Taxane-based regimens as well as sequential regimens such as Taxanes following Anthracycline based regimens, has an impact on survival.

The authors therefore performed a retrospective analysis to evaluate the effect of Total Cumulative Dose (TCD) of adjuvant chemotherapy, on breast cancer outcomes, in women diagnosed with Stage I-III, Hormone Receptor positive or negative, HER2-negative breast cancer, treated with adjuvant FEC (5-FU 500 mg/m2, Epirubicin 100 mg/m2, Cyclophosphamide 500 mg/m2) for 3 cycles followed by Docetaxel 100 mg/m2 for 3 cycles (FEC-D chemotherapy regimen) from 2007 through 2014. Using the historical cutoff of 85% as the optimal Total Cumulative Dose (TCD), this study focused on data from the Alberta Cancer Registry on 1,302 women with Stage I to III breast cancer.

The TCD for cycles 1-6 of less than 85% or 85% and more was calculated. The majority of patients (84%) received 85% or more of the TCD across all six cycles. Sixteen percent (16%) received reduced doses (less than 85% of TCD). Those receiving a TCD of 85% or more were more likely to be younger (median age of 54 yrs) and premenopausal, with a lower number of comorbidities, compared with those with a TCD of less than 85%. The average cumulative dose was also calculated for early (cycles 1-3) and late (cycles 4-6) chemotherapy, to explore the effects of early (FEC) versus late (Docetaxel only) dose reduction. The median follow up was 60 months.

It was noted that the amount of chemotherapy delivered had a significant impact on survival. Patients receiving a TCD of 85% or more had a 5-year Disease Free Survival (DFS) of 85.9% versus 79.2% for those receiving a lower TCD (P=0.025). The 5-year Overall Survival (OS) was also superior at 88.8% versus 80.7% (P<0.001), respectively. When the researchers split the lower TCD group into two cohorts based on dose reduction during cycles 1-3 versus cycles 4-6, they found that outcomes were not compromised when dose reduction occurred only during the later cycles (which were the only cycles to include Docetaxel), suggesting that late dose reductions in chemotherapy may not have as much of an impact on DFS and OS, compared with early dose reductions. The authors hypothesized that majority of cancer cells that are sensitive to chemotherapy are eradicated during the first few treatments, rather than in the later treatments. Further, the amount of Docetaxel that was prescribed in the last three cycles may be higher than needed for the FEC-D regimen. Menopausal status, use of G-CSF and dose delay of 14 days or more, were not shown to affect OS.

It was concluded that early dose reductions in adjuvant FEC-D chemotherapy results in inferior outcomes, with adverse affect on DFS and OS. Conversely, late reductions in chemotherapy dose (Docetaxel only) appear to have minimal impact on survival. Based on this data, the authors recommended that Medical Oncologists should strive to deliver full-dose FEC when prescribing adjuvant FEC-D chemotherapy for breast cancer. Impact of Cumulative Chemotherapy Dose on Survival With Adjuvant FEC-D Chemotherapy for Breast Cancer. Veitch Z, Khan OF, Tilley D, et al. J Natl Compr Canc Netw. 2019;17:957-967.

Late Breaking Abstract – ESMO 2019 VERZENIO® plus FASLODEX® Combination Improves Overall Survival in HR+ Advanced Breast Cancer

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. Approximately 268,600 new cases of invasive breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. Cyclin Dependent Kinases (CDK) play a very important role to facilitate orderly and controlled progression of the cell cycle. Genetic alterations in these kinases and their regulatory proteins have been implicated in various malignancies. Cyclin Dependent Kinases 4 and 6 (CDK4 and CDK6), phosphorylate RetinoBlastoma protein (RB), and initiate transition from the G1 phase to the S phase of the cell cycle. RetinoBlastoma protein has antiproliferative and tumor-suppressor activity and phosphorylation of RB protein nullifies its beneficial activities. CDK4 and CDK6 are activated in hormone receptor positive breast cancer, promoting breast cancer cell proliferation. Further, there is evidence to suggest that endocrine resistant breast cancer cell lines depend on CDK4 for cell proliferation. The understanding of the role of Cyclin Dependent Kinases in the cell cycle, has paved the way for the development of CDK inhibitors.Cell-Cycle-Inhibition-by-ABEMACICLIB-A-CDK4-and-CDK6-Inhibitor

VERZENIO® (Abemaciclib) is an oral, selective inhibitor of CDK4 and CDK6 kinase activity, and prevents the phosphorylation and subsequent inactivation of the Rb tumor suppressor protein, thereby inducing G1 cell cycle arrest and inhibition of cell proliferation. VERZENIO® is structurally distinct from other CDK 4 and 6 inhibitors (such as Ribociclib and Palbociclib) and is 14 times more potent against cyclin D1/CDK 4 and cyclin D3/CDK 6, in enzymatic assays, but potentially less toxic than earlier pan-CDK inhibitors. At higher doses, only VERZENIO® causes significant cancer cell death, compared with other CDK4/6 inhibitors, suggesting that this drug may be affecting proteins, other than CDK4/6. Additionally, preclinical studies have demonstrated that VERZENIO® may have additional therapeutic benefits for a subset of tumors that are unresponsive to treatment or have grown resistant to other CDK4/6 inhibitors. It has also been shown to cross the blood-brain barrier.

The FDA approved VERZENIO® in combination with FASLODEX® (Fulvestrant) in 2017, for women with Hormone Receptor positive (HR-positive), HER2-negative, advanced or metastatic breast cancer, with disease progression following endocrine therapy. This approval was based on the MONARCH-2 study. VERZENIO® was also approved as monotherapy for women and men with HR-positive, HER2-negative advanced or metastatic breast cancer, with disease progression following endocrine therapy and prior chemotherapy in the metastatic setting, based on improved Objective Response Rate (ORR) and PFS (MONARCH-1 study).

MONARCH-2 is an International, double-blind, Phase III study in which 669 patients were randomized in a 2:1 ratio to receive either VERZENIO® plus FASLODEX® (N=446) or placebo plus FASLODEX® (N=223). Enrolled patients had HR-positive, HER2-negative metastatic breast cancer, with disease progression while receiving neoadjuvant or adjuvant endocrine therapy, within 12 months of adjuvant endocrine therapy, or while receiving endocrine therapy for metastatic breast cancer. Patients must not have received more than one endocrine therapy or any prior chemotherapy for metastatic breast cancer. Randomized patients received either VERZENIO® 150 mg or placebo orally twice daily plus FASLODEX® 500 mg IM on Day 1 and Day 15 of cycle 1 and then on Day 1 of cycle 2 and beyond (28-day cycles). Treatment was continued until disease progression or unmanageable toxicities. The mean patient age was 60 years, 82% of patients were postmenopausal, 72% had measurable disease, 56% had visceral disease, and 25% had primary endocrine therapy resistance. About 60% of patients had received chemotherapy in the adjuvant or neoadjuvant setting and 69% of the patients had prior therapy with Aromatase Inhibitors (AI). The Primary end point was Progression Free Survival (PFS), and Secondary end points included Overall Survival (OS), Objective Response Rate (ORR), Duration of Response, Clinical Benefit Rate, Quality of Life, and safety. The authors had previously reported the PFS data and the median PFS for the group receiving VERZENIO® plus FASLODEX® was 16.4 months compared with 9.3 months for those taking placebo with FASLODEX® (HR= 0.55; P<0.0001).

The authors now reported the Overall Survival (OS) data. At a median follow up of 47.7 months, the median OS with the combination of VERZENIO® plus FASLODEX® was 46.7 months compared with 37.3 months for placebo plus FASLODEX® (HR=0.757; P=0.0137). The OS benefit was consistently seen across subgroups, including those with poor prognostic factors such as visceral metastasis (HR=0.675) and primary endocrine therapy resistance (HR=0.686). The updated median PFS with VERZENIO® plus FASLODEX® was 16.9 months compared to 9.3 months with placebo plus FASLODEX® (HR=0.53; P<0.001). The time to second disease progression (PFS2) was also improved with the addition of VERZENIO® at a median 23.1 months versus 20.6 months with placebo plus FASLODEX® (HR, 0.675). VERZENIO® combination also showed a statistically significant improvement in median chemotherapy-free survival compared with placebo/FASLODEX® combination at 25.5 months and 18.2 months, respectively (HR, 0.638). The most common adverse events in the VERZENIO® versus placebo groups were diarrhea neutropenia, nausea and fatigue.

It was concluded that the addition of VERZENIO® to FASLODEX® resulted in a statistically significant improvement in Overall Survival among patients with HR-positive, HER2-negative breast cancer, who had progressed on prior endocrine therapy, significantly delaying the receipt of subsequent chemotherapy. MONARCH 2: Overall survival of abemaciclib plus fulvestrant in patients with HR+, HER2 advanced breast cancer. Sledge Jr GW, Toi M, Neven P, et al. Presented at 2019 ESMO Congress; September 27 to October 1, Barcelona, Spain. Abstract LBA6_PR.

Primary Breast Tumor Surgery Improves Overall Survival in HER2 Positive Advanced Breast Cancer

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. Approximately 268,600 new cases of invasive breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. The HER or erbB family of receptors consist of HER1, HER2, HER3 and HER4. Approximately 15-20% of invasive breast cancers overexpress HER2/neu oncogene, which is a negative predictor of outcomes without systemic therapy. Approximately 50% of HER2-positive breast cancers are Hormone Receptor positive. Patients with HER2-positive metastatic breast cancer are often treated with anti-HER2 targeted therapy along with chemotherapy, irrespective of hormone receptor status, and this has resulted in significantly improved treatment outcomes. HER2-targeted therapies include HERCEPTIN® (Trastuzumab), TYKERB® (Lapatinib), PERJETA® (Pertuzumab) and KADCYLA® (ado-Trastuzumab emtansine). Dual HER2 blockade with HERCEPTIN® and PERJETA®, given along with chemotherapy (with or without endocrine therapy), as first line treatment, in HER2 positive metastatic breast cancer patients, was shown to significantly improve Progression Free Survival (PFS) as well as Overall Survival. The superior benefit with dual HER2 blockade has been attributed to differing mechanisms of action and synergistic interaction between HER2 targeted therapies. Not all HER2-positive, Hormone Receptor positive metastatic breast cancer patients, are candidates for chemotherapy. These patients however may benefit from anti-HER2 targeted therapy given along with endocrine therapy.

Breast surgery is often not a consideration for patients with metastatic breast cancer. However, breast surgery can be offered for palliation of symptoms, taking into consideration the risks and benefits of such intervention, in a patient with an ulcerated, bleeding, or a fungating tumor mass, that cannot be controlled with systemic therapy. A few previously published studies which evaluated the addition of surgical resection of the primary tumor to systemic therapy, among patients with metastatic HER2-positive breast cancer, have provided mixed results, with one study showing improved outcomes. The authors therefore conducted a retrospective study to examine the impact of primary breast tumor resection on survival, in HER2-positive Stage IV breast cancer patients, treated with HER2 targeted therapy.

This retrospective cohort study included records of 3,231 women with HER2 positive Stage IV breast cancer from the National Cancer Database, from 2010 to 2012. Of these women, 89.4% had received chemotherapy/anti-HER2 targeted therapies, 37.7% had received endocrine therapy, 31.8% had received radiation and 25% of the patients had bone only metastasis. Overall, 1,130 women (35%) underwent primary breast tumor resection. The mean age of those who had surgery was 56 years and the Primary endpoints were receipt of surgery and Overall Survival (OS).

At a median follow-up of 21.2 months, the median OS for patients who had surgery was 25 months compared with 18 months for those who did not undergo surgical resection (HR=0.56; P=0.0004). This suggested a 44% reduction in the risk of death with primary breast tumor resection. Patients having Medicare/other government or private insurance, as well as those who received radiation, chemotherapy/anti-HER2 targeted therapies and endocrine therapy were more likely to have surgery. Additionally, Caucasian women were also more likely than non-Hispanic black women, to have surgery. These findings suggested that women with Medicare or private insurance as well as white women were also more likely to have surgery and less likely to die of their disease, than non-Hispanic black women, and those with Medicaid or no insurance.

It was concluded that after controlling for independent variables, surgery of the primary site, in patients with metastatic HER2 positive breast cancer who are managed with present day contemporary treatment, is associated with improved Overall Survival. Breast surgery should therefore be discussed as a part of the treatment strategy, for qualified women, in this patient group. The impact of primary tumor surgery on survival in HER2 positive stage IV breast cancer patients in the current era of targeted therapy. Mudgway R, Chavez de Paz Villaneva C, Lin AC, et al. Presented at AACR Annual Meeting; March 29 to April 3, 2019; Atlanta, GA. Abstract 4873.

KISQALI® Improves Overall Survival in Advanced Breast Cancer

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. About 268,600 new cases of female breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. Breast cancer is the second leading cause of cancer death in the US. Approximately 70% of breast tumors express Estrogen Receptors and/or Progesterone Receptors and these patients are often treated with anti-estrogen therapy as first line treatment. The incidence of breast cancer among women under the age of 50 has been increasing by 0.2% per year. Premenopausal breast cancer may be biologically different than post menopausal breast cancer and diagnosis of breast cancer at a young age has been associated with adverse outcomes and less sensitivity to endocrine therapy. Further, premenopausal women are often excluded from hormone therapy trials. The incidence of metastatic disease at the time of diagnosis among patients with Hormone Receptor (HR)- positive breast cancer, has been increasing by about 2% per year.

Cyclin Dependent Kinases (CDK) play a very important role to facilitate orderly and controlled progression of the cell cycle. Genetic alterations in these kinases and their regulatory proteins have been implicated in various malignancies. Cyclin Dependent Kinases 4 and 6 (CDK4 and CDK6) phosphorylate RetinoBlastoma protein (RB), and initiate transition from the G1 phase to the S phase of the cell cycle. RetinoBlastoma protein has antiproliferative and tumor-suppressor activity and phosphorylation of RB protein nullifies its beneficial activities. CDK4 and CDK6 are activated in HR-positive breast cancer, promoting breast cancer cell proliferation. Further, there is evidence to suggest that endocrine resistant breast cancer cell lines depend on CDK4 for cell proliferation. The understanding of the role of Cyclin Dependent Kinases in the cell cycle, has paved the way for the development of CDK inhibitors.Cell-Cycle-Inhibition-by-RIBOCICLIB-A-CDK4-and-CDK6-Inhibitor

There are presently three CDK4/6 inhibitors approved by the FDA and they include KISQALI® (Ribociclib), IBRANCE® (Palbociclib) and VERZENIO® (Abemaciclib). All three agents have demonstrated similar, significantly prolonged Progression Free Survival (PFS) when administered in combination with endocrine therapy, as first-line treatment, in women with HR-positive metastatic breast cancer (MONALEESA-2 with KISQALI®, PALOMA-2 with IBRANCE® and MONARCH-3 with VERZENIO®). These trials for the first-line treatment of advanced breast cancer however excluded premenopausal women. The toxicities were slightly different with neutropenia more commonly encountered in the IBRANCE® and KISQALI® studies and diarrhea more often noted with VERZENIO®. KISQALI® (Ribociclib) is an orally bioavailable, selective, small-molecule inhibitor of CDK4/6 that blocks the phosphorylation of RetinoBlastoma protein, thereby preventing cell-cycle progression and inducing G1 phase arrest. It is four times more selective for CDK4 than for CDK6.

The MONALEESA-7 trial is an international, randomized, double-blind, placebo-controlled, Phase III trial in which KISQALI® in combination with endocrine therapy was compared with placebo in combination with endocrine therapy, in premenopausal or perimenopausal women with HR-positive, HER2- negative advanced breast cancer. Patients (N=672) were randomly assigned in a 1:1 ratio, to receive KISQALI® at 600 mg orally once daily for 21 days of each 28 day cycle (N=335), or matching placebo (N=337). Both groups received ZOLADEX® (Goserelin) 3.6 mg administered subcutaneously on day 1 of each 28 day cycle. Patients also received either a nonsteroidal Aromatase Inhibitor (Letrozole 2.5 mg or Anastrozole 1 mg) or Tamoxifen 20 mg, orally once daily continuously. The choice of endocrine therapy was made on the basis of the patient’s previous adjuvant or neoadjuvant therapy or investigator or patient preference. Crossover was not permitted between the two treatment groups. Patients were stratified according to the presence or absence of liver or lung metastases, previous chemotherapy for advanced disease and endocrine therapy. The Primary end point was Progression Free Survival (PFS) and Secondary endpoint included Overall Survival (OS). The superior PFS data with KISQALI® compared to endocrine therapy alone, was previously reported. The authors herein report the results on Overall Survival.

After a median follow up of 34.6 months, the addition of KISQALI® to endocrine therapy resulted in significantly longer Overall Survival, compared to endocrine therapy alone. The estimated OS at 42 months was 70.2% in the KISQALI® group and 46.0% in the placebo group (HR for death=0.71; P=0.00973), suggesting a 29% reduction in the risk of death. No new safety signals were observed and in the KISQALI® group, more instances of QT-interval prolongation were observed in patients who received Tamoxifen than in those who received an Aromatase Inhibitor, but without symptomatic arrhythmias or Torsades de pointes.

It was concluded that KISQALI® along with endocrine therapy significantly prolonged Overall Survival, compared to endocrine therapy alone, among pre and perimenopausal patients with advanced HR-positive, HER2-negative breast cancer and these findings represent a major treatment advance in this patient group. Overall Survival with Ribociclib plus Endocrine Therapy in Breast Cancer. Im S-A, Lu Y-S, Bardia A, et al. N Engl J Med 2019; 381:307-316.

US Preventive Services Task Force Recommendations on BRCA Mutation Testing

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. About 268,600 new cases of female breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. Breast cancer is the second leading cause of cancer death in the US. DNA can be damaged due to errors during its replication or as a result of environmental exposure to ultraviolet radiation from the sun or other toxins. The tumor suppressor genes such as BRCA1 (Breast Cancer 1) and BRCA2 help repair damaged DNA and thus play an important role in maintaining cellular genetic integrity, failing which these genetic aberrations can result in malignancies. The BRCA1 gene is located on the long (q) arm of chromosome 17 whereas BRCA2 is located on the long arm of chromosome 13. These mutations can be inherited from either of the parents in an autosomal dominant pattern and a child has a 50 percent chance of inheriting this mutation and the deleterious effects of the mutations are seen even when an individual’s second copy of the gene is normal.

It is estimated that BRCA1/2 gene mutations occur in approximately 1 in 400 women in the general population and account for 5-10% of breast cancer cases and 15% of ovarian cancer cases. The estimated prevalence of potentially harmful BRCA1/2 mutations is 6% in women with cancer onset before age 40 years, and 2.1% among Ashkenazi Jewish women. Among individuals with a family history of breast or ovarian cancer, BRCA1 mutation prevalence is approximately 13%, BRCA2 mutation prevalence is about 8%, and prevalence of either mutation is about 20%. Mutations in the BRCA1/2 genes increase breast cancer risk by 45-65% by age 70 years. The risk of ovarian, fallopian tube, or peritoneal cancer, increases to 39% for BRCA1 mutations, and 10-17% for BRCA2 mutations.

The US Preventive Services Task Force (USPSTF) in this publication updated the 2013 recommendations on risk assessment, genetic counseling, and genetic testing for BRCA-related cancer. These recommendations are based on the evidence of both the benefits and harms of the service and this assessment does not consider the costs of providing a service.

The USPSTF reviewed the evidence on risk assessment, genetic counseling, and genetic testing for potentially harmful BRCA1/2 mutations in asymptomatic women who have never been diagnosed with BRCA-related cancer, as well as those with a previous diagnosis of breast, ovarian, tubal, or peritoneal cancer who have completed treatment and are considered cancer free. In addition, the USPSTF reviewed interventions to reduce the risk for breast, ovarian, tubal, or peritoneal cancer in women with potentially harmful BRCA1/2 mutations, including intensive cancer screening, medications, and risk-reducing surgery.

Recommendations

1) The USPSTF recommended that primary care clinicians assess women with a personal or family history of breast, ovarian, tubal, or peritoneal cancer or who have an ancestry associated with BRCA1/2 gene mutations, with an appropriate brief familial risk assessment tool. Women with a positive result on the risk assessment tool should receive genetic counseling and, if indicated after counseling, genetic testing.

2) The USPSTF recommends against routine risk assessment, genetic counseling, or genetic testing for women whose personal or family history or ancestry is not associated with potentially harmful BRCA1/2 gene mutations.

Risk Assessment

Clinicians should obtain medical and family history specifically inquiring patients about specific types of cancer, primary cancer sites, which family members were affected, whether relatives had multiple types of primary cancer, the age at diagnosis, age at death, and sex of affected family members, both immediate (parents and siblings) as well as more distant (aunts, uncles, grandparents, and cousins). Women who have a family or personal history of breast, ovarian, tubal, or peritoneal cancer should be evaluated by clinicians, to determine the need for in-depth genetic counseling, using appropriate familial risk assessment tools, recognized by the USPSTF. Familial risk assessment factors include breast cancer diagnosis before age 50 years, bilateral breast cancer, presence of both breast and ovarian cancer in one individual, male family members with breast cancer, multiple cases of breast cancer in the family, one or more family members with 2 primary types of BRCA-related cancer (such as ovarian cancer), and Ashkenazi Jewish ancestry. Breast cancer risk assessment models such as the National Cancer Institute Breast Cancer Risk Assessment Tool, which is based on the Gail model are not designed to identify BRCA-related cancer risk and should not be used for this purpose.

Genetic Counseling

Genetic counseling includes detailed kindred analysis and risk assessment for potentially harmful BRCA1/2mutations, identification of individuals for testing, discussion of the benefits and harms of genetic testing, interpretation of results after testing, and discussion of management options. Genetic counseling should be performed by trained health professionals, including suitably trained primary care clinicians.

Genetic Testing

Testing for BRCA1/2 mutations should be performed only when an individual with history suggesting inherited cancer susceptibility, is willing to talk with a qualified health professional, trained to provide genetic counseling and interpret test results, and when test results will aid in decision-making. BRCA mutation testing should begin with a relative with known BRCA-related cancer, including male relatives, to determine if a clinically significant mutation is detected in the family, before testing individuals without cancer. If an affected family member with a BRCA-related cancer is not available, then the relative with the highest probability of mutation should be tested. Reporting BRCA1/2 mutations identified by genetic tests should include a 5-tier terminology system, using the terms “pathogenic,” “likely pathogenic,” “uncertain significance,” “likely benign,” and “benign.

Treatment and Interventions for women with harmful BRCA1/2 mutations

The USPSTF recommends that clinicians offer intensive screening and risk-reducing medications such as Tamoxifen, Raloxifene, or Aromatase Inhibitors to women at increased risk for breast cancer and at low risk for adverse medication effects. General care for these individuals may include risk-reducing mastectomy and salpingo-oophorectomy.

US Preventive Services Task Force. Risk Assessment, Genetic Counseling, and Genetic Testing for BRCA-Related Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2019;322:652-665.

Adjuvant Treatment with PROLIA® Improves Disease Free Survival in Early Stage Breast Cancer

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. About 268,600 new cases of female breast cancer will be diagnosed in 2019 and about 41,760 women will die of the disease. Approximately 75% of patients with breast cancer are hormone receptor positive (Estrogen Receptor/Progesterone Receptor positive) and this is a predictor of response to endocrine therapy. These patients are often treated with anti-estrogen therapy as first line treatment. In premenopausal woman, the ovary is the main source of estrogen production, whereas in postmenopausal women, the primary source of estrogen is the Aromatase enzyme mediated conversion of androstenedione and testosterone to estrone and estradiol in extragonadal/peripheral tissues. In postmenopausal women with hormone receptor-positive, early-stage breast cancer, treatment with adjuvant Aromatase Inhibitors is the standard of care.

ARIMIDEX® (Anastrozole), FEMARA® (Letrozole) and AROMASIN® (Exemestane) are Aromatase Inhibitors that bind reversibly to the Aromatase enzyme and inhibit the conversion of androgens to estrogens in the extra-gonadal tissues. Aromatase Inhibitors however are associated with accelerated bone loss, leading to a decrease in Bone Mineral Density (BMD) and can thus cause osteopenia and osteoporosis, thereby increasing fracture risk.Interplay-of-Bone-Formation-and-Bone-Resorption

PROLIA® (Denosumab) is a monoclonal antibody that inhibits osteoclast formation, function and survival, by selectively targeting the RANK ligand. The RANK-RANK ligand system is an important mediator of signaling in the genesis of osteoclasts and bone resorption. Additionally, the RANK-RANK ligand system has been implicated in antitumor immunity and may have a role in suppressing tumor agenesis. It has been hypothesized that targeting RANK with anti-RANK inhibitor might reverse the immunosuppressive effect of the RANK-RANK ligand signaling pathway.

ABCSG-18 is a randomized, double-blind, placebo controlled, Phase III trial in which the authors evaluated the benefits of the anti-RANK ligand antibody PROLIA® on bone health, in postmenopausal patients, with early stage hormone receptor-positive breast cancer, treated with Aromatase Inhibitors. Of the 3425 patients enrolled in this study, 3420 patients were randomly assigned 1:1 to receive PROLIA® 60 mg (N=1711) or matching placebo (N=1709), subcutaneously every 6 months, during Aromatase Inhibitor therapy. Majority of the patients participating in this study had breast cancer with good prognosis and only 25% of the patients required adjuvant chemotherapy. Patient received a median of 7 doses of PROLIA®. The Primary endpoint was the time to first clinical fracture after randomization. The Secondary endpoint was Disease Free Survival (defined as time from randomization to first evidence of local or distant metastasis, contralateral breast cancer, secondary carcinoma, or death from any cause) in the intention-to-treat population. The Primary endpoint of the ABCSG-18 trial was met (The Lancet 2015;386:433-443) and the use of PROLIA® as an adjuvant to Aromatase Inhibitor therapy significantly delayed time to first clinical fracture, compared to Placebo (HR=0.50; P<0.0001). The authors in publication reported the Secondary endpoint of Disease Free Survival (DFS) outcomes from this study.

After a median follow-up of 73 months, there was a significant improvement in the Disease Free Survival among patients in the PROLIA® group compared to the placebo group (HR=0•82; P=0.026). In the PROLIA® group, the DFS was 89.2% at 5 years and 80.6% at 8 years of follow-up, compared with 87.3% at 5 years and 77.5% at 8 years in the placebo group. The total number of adverse events was similar in the PROLIA® and placebo groups and there were no reported cases of osteonecrosis of the jaw bone or atypical femoral fractures.

It was concluded that PROLIA® constitutes an effective and safe adjuvant treatment for patients with postmenopausal hormone receptor-positive early breast cancer receiving Aromatase Inhibitor therapy, with a Disease Free Survival benefit similar to bisphophonates, but with a better toxicity profile and convenient subcutaneous injections twice yearly. Adjuvant denosumab in postmenopausal patients with hormone receptor-positive breast cancer (ABCSG-18): disease-free survival results from a randomised, double-blind, placebo-controlled, phase 3 trial. Gnant M, Pfeiler G, Steger GG, et al. Lancet Oncol 2019;20:339-351