Tag: Rectal Cancer

SUMMARY: The FDA on January 16, 2025, approved Sotorasib (LUMAKRAS®) with Panitumumab (VECTIBIX®) for adult patients with KRAS G12C-mutated metastatic ColoRectal Cancer (mCRC), as determined by an FDA-approved test, who have received prior Fluoropyrimidine, Oxaliplatin, and Irinotecan-based chemotherapy. The FDA also approved the therascreen KRAS RGQ PCR Kit (QIAGEN GmbH) as a companion diagnostic device to aid in identifying patients with colorectal cancer whose tumors harbor KRAS G12C mutations and who may be eligible for LUMAKRAS® with VECTIBIX®.

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 154,270 new cases of CRC will be diagnosed in the United States in 2025 and about 52,900 patients will die 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 (ERBITUX®) 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 Regorafenib (STIVARGA®), 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 to cancer cells. KRAS is the most frequently mutated oncogene in human cancers and these cancers 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.

Sotorasib 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.

The present FDA approval was based on CodeBreaK 300 trial, which 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) and Duration of Response (DOR).

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 and the median DOR was 4.4 months in the 960 mg Sotorasib/Panitumumab group. 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. The final analysis of PFS for patients randomized to the 240 mg Sotorasib/Panitumumab arm compared to the standard of care groups was not statistically significant.
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 Sotorasib 960 mg in combination with Panitumumab resulted in significantly longer Progression Free Survival and a higher Objective Response Rate than standard of care 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.

SUMMARY: The FDA on December 20, 2024, granted accelerated approval to Encorafenib (BRAFTOVI®) in combination with Cetuximab (ERBITUX®) and modified Fluorouracil, Leucovorin, and Oxaliplatin (mFOLFOX6) for patients with metastatic colorectal cancer with a BRAF V600E mutation, as detected by an FDA-approved test (Qiagen therascreen BRAF V600E RGQ polymerase chain reaction kit). 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 152,810 new cases of CRC were diagnosed in the United States in 2024 and about 53,010 patients died of the disease. The lifetime risk of developing CRC is about 1 in 23.

Advanced colon cancer is often incurable and standard chemotherapy when combined with anti EGFR (Epidermal Growth Factor Receptor) targeted monoclonal antibodies such as VECTIBIX® (Panitumumab) and ERBITUX® (Cetuximab) as well as anti VEGF agent AVASTIN® (Bevacizumab), have demonstrated improvement in Progression Free Survival (PFS) and Overall Survival (OS). The benefit with anti EGFR agents however is only demonstrable in patients with metastatic CRC (mCRC) whose tumors do not harbor KRAS mutations in codons 12 and 13 of exon 2 (KRAS Wild Type). It is now also clear that even among the KRAS Wild Type patient group about 15-20% have other rare mutations such as NRAS and BRAF mutations, which confer resistance to anti EGFR agents. 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. Approximately 8-15% of all metastatic CRC tumors present with BRAF V600E mutations, and BRAF V600E is recognized as a marker of poor prognosis in this patient group. These patients tend to have aggressive disease with a higher rate of peritoneal metastasis and do not respond well to standard treatment intervention. Approximately 20% of the BRAF-mutated population in the metastatic setting has MSI-High tumors, but MSI-High status does not confer protection to this patient group.

The Mitogen-Activated Protein Kinase pathway (MAPK pathway) is an important signaling pathway which enables the cell to respond to external stimuli. This pathway plays a dual role, regulating cytokine production and participating in cytokine dependent signaling cascade. The MAPK pathway of interest is the RAS-RAF-MEK-ERK pathway. The RAF family of kinases includes ARAF, BRAF and CRAF signaling molecules. BRAF is a very important intermediary of the RAS-RAF-MEK-ERK pathway. The BRAF V600E mutations results in constitutive activation of the MAP kinase pathway. Inhibiting BRAF can transiently reduce MAP kinase signaling. However, this can result in feedback upregulation of EGFR signaling pathway, which can then reactivate the MAP kinase pathway. This aberrant signaling can be blocked by dual inhibition of both BRAF and EGFR. It should be noted that BRAF V600E-mutated CRC is inherently less sensitive to BRAF inhibition than Malignant Melanoma.

BRAFTOVI® (Encorafenib) is a BRAF inhibitor and has target binding characteristics that differ from other BRAF inhibitors such as ZELBORAF® (Vemurafenib) and TAFINLAR® (Dabrafenib), with a prolonged target dissociation half-life and higher potency. The FDA in 2020, approved Encorafenib in combination with Cetuximab (ERBITUX®) for the treatment of adult patients with metastatic ColoRectal Cancer (mCRC) with a BRAF V600E mutation, detected by an FDA-approved test, after prior therapy, based on the BEACON CRC trial. However, first line treatment options for this group of patients remains an unmet need.

BREAKWATER is an ongoing, active-controlled, open-label, multicenter, randomized, Phase 3 study in which first line Encorafenib plus Cetuximab plus or minus chemotherapy was compared with Standard of Care chemotherapy alone, in patients with BRAF V600E-mutant mCRC. In this trial, patients were initially randomly assigned 1:1:1 to receive either Encorafenib orally once daily with Cetuximab IV infusion every 2 weeks (Encorafenib plus Cetuximab arm), Encorafenib orally once daily with Cetuximab IV infusion every 2 weeks and mFOLFOX6 every 2 weeks (Encorafenib plus Cetuximab plus mFOLFOX6 arm), or control group patients who received mFOLFOX6 (Leucovorin, Fluorouracil and Oxaliplatin) or FOLFOXIRI (Leucovorin, Fluorouracil, Oxaliplatin, and Irinotecan), both every 2 weeks, or Capecitabine plus Oxaliplatin (every 3 weeks), each with or without Bevacizumab . The trial was subsequently amended to limit randomization and compare the Encorafenib plus Cetuximab plus mFOLFOX6 group and the control group. Treatment in both groups continued until disease progression, unacceptable toxicity. The Primary endpoint was Progression Free Survival (PFS) and Objective Response Rate (ORR) and Secondary endpoints included Duration of Response, Overall survival, Time to Response and patient Reported Outcomes.

The present FDA accelerated approval was based on the results of the Encorafenib plus Cetuximab plus mFOLFOX6 group, compared to the control group. The major efficacy outcome measure was confirmed ORR assessed by Blinded Independent Central Review and evaluated in the first 110 patients randomly assigned in each treatment group. The ORR was 61% in the Encorafenib plus Cetuximab plus mFOLFOX6 group compared to 40% in the control group. Median Duration of Response was 13.9 months and 11.1 months in the two groups respectively. PFS and OS data in this ongoing trial are immature. The most common grade 3 or 4 laboratory abnormalities were increased lipase and decreased neutrophil count.

In conclusion, a combination of Encorafenib and Cetuximab plus mFOLFOX6 resulted in a statistically significant and clinically meaningful improvement in Response Rate and Durability of Response in treatment-naïve metastatic CRC patients with a BRAF V600E mutation. Continued approval for this indication is contingent upon verification of clinical benefit.

https://www.fda.gov/drugs/resources-information-approved-drugs/fda-grants-accelerated-approval-encorafenib-cetuximab-and-mfolfox6-metastatic-colorectal-cancer-braf

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.

SUMMARY: The FDA on June 21, 2024, granted accelerated approval to Adagrasib (KRAZATI®) plus Cetuximab (ERBITUX®) for adults with KRAS G12C-mutated locally advanced or metastatic Colorectal Cancer (CRC), as determined by an FDA-approved test, who have received prior treatment with Fluoropyrimidine, Oxaliplatin, and Irinotecan-based chemotherapy.

Colorectal cancer is the third most common cancer diagnosed in both men and women in the United States. The American Cancer Society estimates that approximately 152,810 new cases of colorectal cancer will be diagnosed in the United States in 2024 and about 53,010 patients will die of the disease. The lifetime risk of developing colorectal cancer is about 1 in 23.

Approximately 15-25% of the patients with colorectal cancer present with metastatic disease at the time of diagnosis (synchronous metastases) and 50-60% of the patients with colorectal cancer will develop metastatic disease during the course of their illness. First line treatment of metastatic colorectal cancer 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 (VECTIBIX®). 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.

Adagrasib (KRAZATI®) is a potent, orally available, small molecule covalent inhibitor of KRAS G12C. This drug irreversibly and selectively binds KRAS G12C in its inactive, GDP-bound state. Unlike Sotorasib (LUMAKRAS®)), which is also a selective covalent inhibitor of KRAS G12C, Adagrasib has a longer drug half-life of 23 hours, as compared to 5 hours for Sotorasib, has dose-dependent extended exposure, and can penetrate the CNS. 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.

Cetuximab (ERBITUX®) is an anti-EGFR monoclonal antibody that is indicated for the treatment of RAS wild-type metastatic colorectal cancer, either as monotherapy or in combination with chemotherapy. Combining Cetuximab with Adagrasib may overcome treatment resistance and enhance the inhibition of KRAS-dependent signaling and improve outcomes.

The present FDA approval was based on the ongoing KRYSTAL-1, multicenter, expansion cohort Phase 1-2 trial, in which the use of Adagrasib as monotherapy or in combination with Cetuximab was evaluated in patients with previously treated metastatic colorectal cancer with mutant KRAS G12C. Eligible patients had locally advanced or metastatic KRAS G12C-mutated colorectal cancer, and had previous treatment with Fluoropyrimidine, Oxaliplatin, and Irinotecan-based chemotherapy, and a VEGF inhibitor, if eligible. These patients were heavily pretreated, having received a median of three prior lines of therapy, and their disease had shown resistance to previous treatments. Patients received Adagrasib 600 mg orally twice daily along with Cetuximab 500 mg/m2 IV every two weeks, or 400 mg/m2 IV as initial dose followed by 250 mg/m2 IV weekly. Tumor assessments were performed every 6 weeks. Treatment was continued until disease progression or unacceptable toxicity, Adagrasib discontinuation required Cetuximab discontinuation, however patients could continue Adagrasib if Cetuximab was discontinued. The median patient age was 59 years old, and 51% were women and both treatment groups were well balanced. The Primary efficacy endpoint of the study was the confirmed Overall Response Rate (ORR), assessed by Blinded Independent Central Review (BICR). Secondary endpoints included Duration of Response (DOR), Progression Free Survival (PFS), Overall Survival (OS), and Safety. Efficacy was assessed in 94 (N=94) enrolled patients.

The study met its Primary endpoint and the ORR was 34%. All responses were Partial Responses (PR), indicating a reduction in tumor burden in responding patients. The median Duration of Response was 5.8 months, with 31% of responders experiencing a Duration of Response of at least 6 months. The most common adverse reactions were rash, nausea, vomiting, diarrhea, fatigue, musculoskeletal pain, hepatotoxicity, anemia, headache, dry skin, decreased appetite, abdominal pain, constipation, edema, cough, and peripheral neuropathy.

In conclusion, the KRYSTAL-1 trial has demonstrated that Adagrasib in combination with Cetuximab shows promising clinical activity and a manageable safety profile in heavily pretreated patients with metastatic CRC harboring the KRAS G12C mutation. These findings highlight a potential new treatment option for patients who have limited therapeutic alternatives and underscore the evolving landscape of precision medicine in oncology, particularly in targeting specific mutations that drive tumor growth and survival.

https://www.fda.gov/drugs/resources-information-approved-drugs/fda-grants-accelerated-approval-adagrasib-cetuximab-kras-g12c-mutated-colorectal-cancer.

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.