Tag: Colon Cancer

FDA Approves LONSURF® with Bevacizumab for Advanced Refractory Colorectal Cancer

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SUMMARY: The FDA on August 2, 2023, approved LONSURF® (Trifluridine and Tipiracil with Bevacizumab, for metastatic ColoRectal Cancer (mCRC) previously treated with Fluoropyrimidine, Oxaliplatin and Irinotecan-based chemotherapy, an anti-VEGF biological therapy, and if RAS wild-type, an anti-EGFR therapy. 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 will be diagnosed in the United States in 2023 and about 52,550 patients are expected to 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 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).

LONSURF® is a combination of two agents – a novel thymidine-based nucleoside analogue, Trifluridine and a thymidine phosphorylase inhibitor, Tipiracil. Trifluridine incorporates into DNA resulting in DNA damage and cell death. Trifluridine however is rapidly metabolized when taken orally and this is prevented by Tipiracil, which increases the bioavailability of Trifluridine. Single agent LONSURF® was approved by the FDA in 2015 for the treatment of patients with metastatic CRC, who have been previously treated with Fluoropyrimidine, Oxaliplatin and Irinotecan-based chemotherapy, an anti-VEGF biological therapy and if RAS wild-type, an anti-EGFR therapy. This approval was based on the RECOURSE study, which is a pivotal, global, Phase III trial in which LONSURF® significantly improved Overall Survival as well as Progression Free Survival, when compared to placebo in this patient population.

Bevacizumab is a humanized monoclonal antibody that targets VEGF, a cytokine secreted by tumor cells and tumor-associated macrophages. VEGF is responsible for neoangiogenesis, proliferation, and metastasis, through its effects on endothelial cells. Bevacizumab was approved for the treatment of CRC in 2004. Maintenance of VEGF inhibition with Bevacizumab beyond disease progression has shown clinical activity in patients with metastatic CRC. A combination of LONSURF® in combination with Bevacizumab improved Overall Survival in several single-group and randomized Phase II trials.

The present FDA approval was based on SUNLIGHT trial, which is a multinational, multicenter, randomized Phase III study, designed to assess the efficacy and safety of LONSURF® in combination with Bevacizumab, as compared with LONSURF® alone, in patients with refractory metastatic CRC. In this study, a total of 492 patients with refractory metastatic CRC were randomly assigned in a 1:1 ratio to receive LONSURF® along with Bevacizumab (N=246) or LONSURF® alone (N=246). Patients received LONSURF® 35 mg/m2 orally, twice daily, on days 1-5 and on days 8-12 every 28 days. Bevacizumab was administered at a dose of 5 mg/kg IV on days 1 and 15. The 28-day treatment cycle was continued until disease progression or unacceptable toxicities. Bevacizumab monotherapy was not allowed. The two treatment groups were well balanced. Most patients (92%) had received two previous treatment regimens for metastatic disease, all patients had received previous Fluoropyrimidine-based therapy, 72% had received previous anti-VEGF therapy, 94% of the patients with RAS wild-type disease had received previous anti-EGFR therapy, and 30% had RAS wild-type disease. The Primary end point was Overall Survival. Secondary end points included Progression Free Survival, Objective Response and Disease Control Rate, Quality of Life and Safety. The median follow up was 14.2 months in the LONSURF® combination group and 13.6 months in the LONSURF® alone group.

The median Overall Survival was 10.8 months in the combination group and 7.5 months in the LONSURF® alone group (HR=0.61; P<0.001), suggesting a 39% reduction in the risk of death with the combination regimen. The median Progression Free Survival was 5.6 months in the combination group and 2.4 months in the LONSURF® alone group (HR=0.44; P<0.001). These benefits of LONSURF® plus Bevacizumab with respect to Overall Survival and Progression Free Survival were observed in all subgroups examined, including patients with poor prognostic factors. Survival benefits with the combination regimen were observed regardless of age, sex, location of primary disease, number of metastatic sites, RAS mutation status and previous treatment with Bevacizumab. The Objective Response Rate was 6.1% in the combination group versus 1.2% in the LONSURF® alone group. The median time to worsening of the ECOG PS from 0 or 1 to 2 or more was 9.3 months in the combination group and 6.3 months in the LONSURF® alone group (HR=0.54). The addition of Bevacizumab to LONSURF® did not increase the risk of serious adverse events or treatment discontinuation. The most common adverse events in both groups were neutropenia, nausea, and anemia.

It was concluded from this study that among patients with refractory metastatic colorectal cancer, treatment with LONSURF® plus Bevacizumab resulted in longer Overall Survival and Progression Free Survival, compared to LONSURF® alone, and this benefit was noted in all subgroups of patients.

Trifluridine–Tipiracil and Bevacizumab in Refractory Metastatic Colorectal Cancer. Prager GW, Taieb J, Fakih M, et al., for the SUNLIGHT Investigators. N Engl J Med 2023; 388:1657-1667

Tucatinib plus Trastuzumab for HER2-Positive Metastatic Colorectal Cancer

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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 will be diagnosed in the United States in 2023 and about 52,550 patients are expected to 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 include Oxaliplatin or Irinotecan, in combination with a Fluoropyrimidine and Leucovorin (FOLFOX or FOLFIRI), 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.

Human Epidermal Growth Factor Receptor 2 (HER2) is overexpressed in 3-5% of patients with RAS wild-type metastatic colorectal cancer. HER2-positive tumors are IHC3+ by Immunohistochemistry (IHC) or IHC2+/FISH [Fluorescence in Situ Hybridization] amplified. Previously published studies have indicated that patients with HER2-positive CRC have less benefit from EGFR targeted therapies. In the HERACLES trial, a combination of two HER2 targeted therapies prolonged Overall Survival (OS) in RAS wild-type metastatic colorectal cancer.

Tucatinib (TUKYSA®) is an oral Tyrosine Kinase Inhibitor that is highly selective for the kinase domain of HER2, with minimal inhibition of Epidermal Growth Factor Receptor. Trastuzumab (HERCEPTIN®) is a humanized monoclonal antibody targeting HER2/neu oncogene.

MOUNTAINEER is a U.S. and European multicenter, open-label, randomized, prospective, Phase II study, conducted among patients with previously treated HER2-positive metastatic colorectal cancer. This U.S. investigator-sponsored trial initially consisted of a single cohort (Cohort A) of patients who received Tucatinib 300 mg orally BID in combination with Trastuzumab 8 mg/kg IV given as a loading dose on Cycle 1, Day 1, followed by maintenance dose of Trastuzumab 6 mg/kg IV on Day 1 every three weeks thereafter. Patients were treated until disease progression or unacceptable toxicity. This trial was subsequently expanded globally to include patients who were randomized to receive Tucatinib plus Trastuzumab (Cohort B) or Tucatinib monotherapy (Cohort C). Eligible patients (N=114) were required to have HER2-positive, RAS wild-type, unresectable or metastatic colorectal cancer and prior treatment with Fluoropyrimidine, Oxaliplatin, Irinotecan, and an anti-Vascular Endothelial Growth Factor (VEGF) monoclonal antibody. Patients whose tumors were MisMatch Repair (dMMR) deficient or were MicroSatellite Instability-High (MSI-H) must also have received an anti PD-1 monoclonal antibody. Patients who received prior anti-HER2 targeted therapy were excluded. HER2 amplification was identified by Next Generation Sequencing in 61% of patients, by an IHC test score of 3+ in 40%, and by an IHC test score of 2+ and FISH amplification in 32%. The median age was 56 years, 58% were male, and 77% were Caucasian. Of patients who received combination therapy, 85% had left-sided primaries, 78% had received 2 or more lines of prior therapy, and 40% had received 3 or more lines of prior therapy. Over two thirds of the patients had liver or lung metastases. The Primary endpoint was Objective Response Rate (ORR) as assessed by blinded Independent Central Review (ICR) in patients receiving the combination of Tucatinib and Trastuzumab (Cohorts A and B). Secondary endpoints included Duration of Response, Progression Free Survival (PFS), Overall Survival (OS) and safety and tolerability of the combination regimen.

At a median follow up of 20.7 months, the ORR among Cohort A and B patients treated with a combination of Tucatinib and Trastuzumab (N=84) was 38.1% and the median Duration of Response was 12.4 months. The Disease Control Rate was 71.4%. The median Progression Free Survival was 8.2 months, and median Overall Survival was 24.1 months. In the Cohort C patients who received Tucatinib monotherapy (N=30), the ORR was only 3.3% and participants who did not respond to Tucatinib monotherapy by 12 weeks or had disease progressed at any time had the option to receive the combination of Tucatinib and Trastuzumab. Tucatinib in combination with Trastuzumab was well tolerated. Grade 1 or 2 diarrhea was the most common adverse event, followed by fatigue and nausea. Treatment discontinuation due to adverse events was low at 5.8%.

It was concluded that in this largest prospective trial to date among patients with chemotherapy-refractory HER2-positive, RAS wild-type metastatic colorectal cancer, Tucatinib in combination with Trastuzumab demonstrated durable and clinically meaningful antitumor activity and is a new chemotherapy-free treatment option for this group of patients. Based on these results, the FDA in January 2023, granted accelerated approval to Tucatinib in combination with Trastuzumab for RAS wild-type, HER2-positive unresectable or metastatic colorectal cancer that has progressed following Fluoropyrimidine, Oxaliplatin, and Irinotecan-based chemotherapy. Studies are underway investigating Tucatinib plus Trastuzumab in earlier lines of therapy.

Tucatinib plus trastuzumab for chemotherapy-refractory, HER2-positive, RAS wild-type unresectable or metastatic colorectal cancer (MOUNTAINEER): a multicentre, open-label, phase 2 study. Strickler JH, Cercek A, Siena S, et al. The Lancet Oncology 2023;24:496-508.

LONSURF® Plus Bevacizumab Improves Overall Survival in Advanced Refractory Colorectal Cancer

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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 will be diagnosed in the United States in 2023 and about 52,550 patients are expected to 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 include Oxaliplatin or Irinotecan, in combination with a Fluoropyrimidine and Leucovorin (FOLFOX or FOLFIRI), 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).

LONSURF® is a combination of two agents – a novel thymidine-based nucleoside analogue, Trifluridine and a thymidine phosphorylase inhibitor, Tipiracil. Trifluridine incorporates into DNA resulting in DNA damage and cell death. Trifluridine however is rapidly metabolized when taken orally and this is prevented by Tipiracil, which increases the bioavailability of Trifluridine. LONSURF® was approved by the FDA in 2015 for the treatment of patients with metastatic CRC, who have been previously treated with Fluoropyrimidine, Oxaliplatin and Irinotecan-based chemotherapy, an anti-VEGF biological therapy and if RAS wild-type, an anti-EGFR therapy. This approval was based on the RECOURSE study, which is a pivotal, global, phase III trial in which LONSURF® significantly improved Overall Survival as well as Progression Free Survival, when compared to placebo in this patient population.

Bevacizumab is a humanized monoclonal antibody that targets VEGF, a cytokine secreted by tumor cells and tumor-associated macrophages. VEGF is responsible for neoangiogenesis, proliferation, and metastasis, through its effects on endothelial cells. Bevacizumab was approved for the treatment of CRC in 2004. Maintenance of VEGF inhibition with Bevacizumab beyond disease progression has shown clinical activity in patients with metastatic CRC. A combination of LONSURF® in combination with Bevacizumab improved Overall Survival in several single-group and randomized Phase II trials.

SUNLIGHT trial is a multinational, multicenter, randomized Phase III study, designed to assess the efficacy and safety of LONSURF® in combination with Bevacizumab, as compared with LONSURF® alone, in patients with refractory metastatic CRC. In this study, a total of 492 patients with refractory metastatic CRC were randomly assigned in a 1:1 ratio to receive LONSURF® along with Bevacizumab (N=246) or LONSURF® alone (N=246). Patients received LONSURF® 35 mg/m2 orally, twice daily, on days 1-5 and on days 8-12 every 28 days. Bevacizumab was administered at a dose of 5 mg/kg IV on days 1 and 15. The 28-day treatment cycle was continued until disease progression or unacceptable toxicities. Bevacizumab monotherapy was not allowed. The two treatment groups were well balanced. Most patients (92%) had received two previous treatment regimens for metastatic disease, all patients had received previous Fluoropyrimidine-based therapy, 72% had received previous anti-VEGF therapy, 94% of the patients with RAS wild-type disease had received previous anti-EGFR therapy, and 30% had RAS wild-type disease. The Primary end point was Overall Survival. Secondary end points included Progression Free Survival, Objective Response and Disease Control Rate, Quality of Life and Safety. The median follow up was 14.2 months in the LONSURF® combination group and 13.6 months in the LONSURF® alone group.

The median Overall Survival was 10.8 months in the combination group and 7.5 months in the LONSURF® alone group (HR=0.61; P<0.001), suggesting a 39% reduction in the risk of death with the combination regimen. The median Progression Free Survival was 5.6 months in the combination group and 2.4 months in the LONSURF® alone group (HR=0.44; P<0.001). These benefits of LONSURF® plus Bevacizumab with respect to Overall Survival and Progression Free Survival were observed in all subgroups examined, including patients with poor prognostic factors. Survival benefits with the combination regimen were observed regardless of age, sex, location of primary disease, number of metastatic sites, RAS mutation status and previous treatment with Bevacizumab. The Objective Response Rate was 6.1% in the combination group versus 1.2% in the LONSURF® alone group. The median time to worsening of the ECOG PS from 0 or 1 to 2 or more was 9.3 months in the combination group and 6.3 months in the LONSURF® alone group (HR=0.54). The addition of Bevacizumab to LONSURF® did not increase the risk of serious adverse events or treatment discontinuation. The most common adverse events in both groups were neutropenia, nausea, and anemia.

It was concluded from this study that among patients with refractory metastatic colorectal cancer, treatment with LONSURF® plus Bevacizumab resulted in longer Overall Survival and Progression Free Survival, compared to LONSURF® alone, and this benefit was noted in all subgroups of patients.

Trifluridine–Tipiracil and Bevacizumab in Refractory Metastatic Colorectal Cancer. Prager GW, Taieb J, Fakih M, et al., for the SUNLIGHT Investigators. N Engl J Med 2023; 388:1657-1667

ctDNA Analysis in Resectable Colorectal Cancer and Efficacy of Adjuvant Chemotherapy

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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 will be diagnosed in the United States in 2023 and about 52,550 patients are expected to die of the disease. The lifetime risk of developing CRC is about 1 in 23.

It is estimated that approximately 30% of patients with Stage II or III CRC and 60–70% of patients after oligometastatic resection experience recurrence. Adjuvant chemotherapy for patients with resected, locally advanced, node-positive (Stage III) colon cancer has been the standard of care since the 1990s. However, not all patients with Stage III disease benefit from adjuvant chemotherapy. In the IDEA trial, the absolute Disease Free Survival benefit of adjuvant chemotherapy for the lowest-risk Stage III group and the highest-risk group was 8% and 20%, respectively, suggesting that a substantial number of patients with low-risk Stage III cancer can safely forgo adjuvant chemotherapy or be considered for treatment de-escalation. Even though 80% of patients with Stage II colon cancer are cured with surgery alone, adjuvant chemotherapy is recommended for patients who have Stage II colon cancer with high-risk clinicopathological features, including tumor penetration of the serosa (T4 disease). However, the benefit of adjuvant chemotherapy for patients with Stage II disease remains unclear, with less than 5% of patients benefiting from adjuvant chemotherapy. There is therefore an unmet need for more precise markers to predict risk of recurrence after surgery for resectable colon cancer, other than clinicopathological risk factors, and thus avoid exposure to unnecessary chemotherapy.

Circulating Tumor DNA (ctDNA) refers to DNA molecules that circulate in the bloodstream after cell apoptosis or necrosis, and can be detected in the cell-free component of peripheral blood samples (Liquid Biopsy) in almost all patients with advanced solid tumors including advanced colorectal cancer. ctDNA is a valuable biomarker and is directly evaluated for evidence of Minimal Residual Disease and allows early detection of relapse. Several studies have shown that detectable ctDNA following curative intent surgery for early stage cancers, including those with Stage II colon cancer, is associated with a very high risk of recurrence (more than 80%) without further adjuvant therapy. It has remained unclear whether adjuvant treatment is beneficial for these ctDNA-positive patients who are at high risk for recurrence.

The GALAXY study/cohort is a part of the CIRCULATE-Japan project, and is a large prospective, observational study that monitors ctDNA status for patients with clinical Stage II-IV or recurrent colorectal cancer following curative-intent surgery. In order to prospectively validate and build upon the previously published evidence, the authors conducted this cohort study to demonstrate that postsurgical ctDNA positivity is predictive of disease recurrence in early-stage CRC. In this publication the researchers reported on postsurgical ctDNA positivity and its associations with patient outcomes, as well as its implications for adjuvant chemotherapy selection, and the association between ctDNA dynamics and prognosis.

The GALAXY study/cohort included 1039 patients with clinical Stage II-III colon cancer or surgically resectable clinical Stage IV or recurrent colorectal cancer. Eligible patients had histologically confirmed colorectal adenocarcinoma, and curative resection planned for clinical Stage II or III, and R0 resection planned for relapsed or Stage IV colorectal cancer. The median age was 69 years. Formalin-Fixed, Paraffin-Embedded (FFPE) tumor tissue samples from surgical resection or biopsy were used for Whole Exome Sequencing (WES) to identify up to 16 patient-specific clonal, somatic Single-Nucleotide Variants (SNVs). These SNVs were then used to design personalized multiplex Polymerase Chain Reaction-based Next-Generation Sequencing assays (Signatera, Natera) for each study participant. Cell-free DNA was extracted from patient plasma at a given time point and was used to detect ctDNA. Plasma samples with at least 2 out of 16 tumor-specific variants detected above a predefined threshold were defined as ctDNA positive (tumor-informed ctDNA analysis. Overall, a total of 8,374 genes were selected for the 1,039 patients and the most frequently selected genes were TP53 (25.6%) and APC (17.5%). It was noted that more than 50% of genes were unique to each patient, suggesting large variability in the mutational landscape of colorectal cancer outside of known hotspot regions.

At a median follow-up of 16.74 months, postsurgical ctDNA positivity at 4 weeks after surgery was associated with higher recurrence risk compared to those patients who were ctDNA negative (61.4% versus 9.5%; HR=10.0, P< 0.0001) and the 18-month Disease Free Survival (DFS) was 38.4% versus 90.5%, respectively. This benefit was noted across all pathological stages. There was however no significant difference in recurrence risk by presurgical ctDNA status across all stages. In multivariate analysis for DFS in patients with pathological Stage II–III disease, ctDNA positivity 4 weeks after surgery was the most significant prognostic factor associated with increased risk for recurrence (HR=10.82, P< 0.001). Further, clinicopathological risk factors often used for staging and prognostication were nonsignificant. ctDNA was more valuable than CEA for relapse detection.

The researchers in this analysis examined the outcomes of ctDNA-positive and ctDNA-negative patients stratified by adjuvant chemotherapy status after adjusting for confounding variables such as age, sex, MSI status, pathological stage, and performance status in this analysis.

It was noted that patients with high-risk Stage II or Stage III disease and ctDNA-positive status 4 weeks after surgery derived significant benefit from adjuvant chemotherapy (adjusted HR=6.59; P< 0.001), and this trend was observed across all pathological stages. ctDNA-positive patients with Stage II–IV disease, not receiving adjuvant chemotherapy were noted to be at a higher risk for recurrence (adjusted HR=5.03; P< 0.001). Approximately 75% of ctDNA-positive patients with pathological Stage I or low-risk Stage II disease did not receive adjuvant chemotherapy and experienced recurrence.

Among the high-risk pathological Stage II or Stage III disease patients with ctDNA-negative status 4 weeks after surgery, there was no statistically significant benefit with adjuvant chemotherapy and the 18-month DFS was 94.9% and 91.5% for the adjuvant chemotherapy group and the observation group, respectively.

Among patients with available ctDNA status both 4 weeks and 12 weeks after surgery, there was a significantly higher risk of recurrence among patients who converted from ctDNA negative to positive, compared to those patients who were persistently negative (HR=14.0; P< 0.001).

Among the patients with ctDNA positivity 4 weeks after surgery, adjuvant chemotherapy was associated with a higher incidence of ctDNA clearance by week 24 after surgery compared with those who did not receive adjuvant therapy (68.48% versus 12.2%; adjusted HR=8.50, P< 0.0001). Among those who did not achieve ctDNA clearance, the DFS was inferior (adjusted HR=11; P< 0.0001).

Based on the results of this large and comprehensive prospective analysis of ctDNA in resectable colorectal cancer, the authors concluded that ctDNA status is a superior prognostic biomarker than the currently used high-risk clinicopathological features, and can identify patients who are at increased risk of recurrence and are likely to benefit from adjuvant chemotherapy.

Molecular residual disease and efficacy of adjuvant chemotherapy in patients with colorectal cancer. Kotani D, Oki E, Nakamura Y, et al. Nature Medicine 2023; 29:127–134.

RNF43 Mutations

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RNF43 mutations were identified in 29% of BRAF V600E-mutated MicroSatellite-Stable (MSS) metastatic ColoRectal Cancer tumors, and this finding was strongly associated with a clinical response to anti-BRAF/EGFR-based combination therapy. When compared to BRAF V600E-mutated, MicroSatellite-Stable metastatic CRC patients without the RNF43 mutation (RNF43 wild-type), patients with BRAF V600E-mutated, MicroSatellite-Stable metastatic CRC carrying a RNF43 mutation had a Response Rate of 72.7% versus 30.8% (P=0.03), longer median Progression Free Survival (10.1 months versus 4.1 months, HR=0.30; P=0.01) and longer median Overall Survival (13.6 months versus 7 months, HR=0.26; P=0.008). Conversely, the predictive value of RNF43 mutations seen in MicroSatellite-Stable tumors was not observed in MicroSatellite Instability (MSI)-High tumors.

FDA Approves Tucatinib with Trastuzumab for Colorectal Cancer

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SUMMARY: The FDA on January 19, 2023, granted accelerated approval to Tucatinib (TUKYSA®) in combination with Trastuzumab for RAS wild-type HER2-positive unresectable or metastatic colorectal cancer that has progressed following Fluoropyrimidine, Oxaliplatin, and Irinotecan-based chemotherapy. 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 will be diagnosed in the United States in 2023 and about 52,550 patients are expected to 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 include Oxaliplatin or Irinotecan, in combination with a Fluoropyrimidine and Leucovorin (FOLFOX or FOLFIRI), 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.

Human Epidermal Growth Factor Receptor 2 (HER2) is overexpressed in 3-5% of patients with RAS wild-type metastatic colorectal cancer. HER2-positive tumors are IHC3+ by Immunohistochemistry or IHC2+/FISH [Fluorescence in Situ Hybridization] amplified. There are currently no FDA-approved therapies that specifically target HER2 in colorectal cancer. Previously published studies have indicated that patients with HER2-positive CRC have less benefit from EGFR targeted therapies. In the HERACLES trial, a combination of two HER2 targeted therapies prolonged Overall Survival (OS) in RAS wild-type metastatic colorectal cancer.

Tucatinib (TUKYSA®) is an oral Tyrosine Kinase Inhibitor that is highly selective for the kinase domain of HER2, with minimal inhibition of Epidermal Growth Factor Receptor. Trastuzumab (HERCEPTIN®) is a humanized monoclonal antibody targeting HER2/neu oncogene.

MOUNTAINEER is a U.S. and European multicenter, open-label, randomized, prospective, Phase II study, conducted among patients with previously treated HER2-positive metastatic colorectal cancer. This U.S. investigator-sponsored trial initially consisted of a single cohort (Cohort A) of patients who received Tucatinib 300 mg orally BID in combination with Trastuzumab 8 mg/kg IV given as a loading dose on Cycle 1, Day 1, followed by maintenance dose of Trastuzumab 6 mg/kg IV on Day 1 every three weeks thereafter. Patients were treated until disease progression or unacceptable toxicity. This trial was subsequently expanded globally to include patients who were randomized to receive Tucatinib plus Trastuzumab (Cohort B) or Tucatinib monotherapy (Cohort C). Enrolled patients were required to have HER2-positive, RAS wild-type, unresectable or metastatic colorectal cancer and prior treatment with Fluoropyrimidine, Oxaliplatin, Irinotecan, and an anti-Vascular Endothelial Growth Factor (VEGF) monoclonal antibody. Patients whose tumors were MisMatch Repair (dMMR) deficient or were MicroSatellite Instability-High (MSI-H) must also have received an anti PD-1 monoclonal antibody. Patients who received prior anti-HER2 targeted therapy were excluded. Over two thirds of the patients had liver or lung metastases and had received a median of 3 prior lines of systemic therapy. The Primary endpoint was Objective Response Rate (ORR) as assessed by blinded Independent Central Review (ICR) in patients receiving the combination of Tucatinib and Trastuzumab (Cohorts A and B). Secondary endpoints included Duration of Response, Progression Free Survival (PFS), Overall Survival (OS) and safety and tolerability of the combination regimen.

At a median follow up of 20.7 months, the ORR among patients treated with a combination of Tucatinib and Trastuzumab (N=84) was 38.1% and the median Duration of Response was 12.4 months. The Disease Control Rate was 71.4%. The median Progression Free Survival was 8.2 months and median Overall Survival was 24.1 months. In the Cohort C patients who received Tucatinib monotherapy (N=30), the ORR by 12 weeks was 3.3% and the Disease Control Rate was 80%. Participants who did not respond to Tucatinib monotherapy by 12 weeks or had disease progressed at any time had the option to receive the combination of Tucatinib and Trastuzumab. Tucatinib in combination with Trastuzumab was well tolerated. Grade 1 or 2 diarrhea was the most common adverse event, followed by fatigue and nausea. Treatment discontinuation due to adverse events was low at 5.8%.

It was concluded that in this largest prospective trial to date among patients with chemotherapy-refractory HER2-positive metastatic colorectal cancer, Tucatinib in combination with Trastuzumab demonstrated durable and clinically meaningful antitumor activity and is a new chemotherapy-free treatment option for this group of patients. Studies are underway investigating Tucatinib plus Trastuzumab in earlier lines of therapy

MOUNTAINEER: Open-label, phase 2 study of tucatinib in combination with trastuzumab for HER2-positive metastatic colorectal cancer. Strickler JH, Cercek A, Siena S, et al: ESMO World Congress on Gastrointestinal Cancers 2022. Abstract LBA-2. Presented July 2, 2022.

RNF43 Mutations Predict Response to Anti-BRAF/EGFR Combination Therapy in BRAF V600E Metastatic Colorectal Cancer

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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 151,030 new cases of CRC will be diagnosed in the United States in 2022 and about 52,580 patients are expected to 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. 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 CRC 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, which is recognized as a marker of poor prognosis in this patient group. These patients predominantly present with right-sided proximal tumors, tend to have aggressive disease with a higher rate of peritoneal metastasis, and do not respond well to standard treatment intervention. Approximately 30% 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. Further, in striking contrast to patients with melanoma harboring BRAF V600E mutations in whom there is a 70% Objective Response Rate with BRAF inhibitor monotherapy, there is little or no clinical benefit with the same treatment among BRAF V600E mutant CRC patients.

Preclinical studies have shown that inhibiting BRAF in colorectal tumors can transiently reduce Mitogen-Activated Protein (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. In the Phase III BEACON Colorectal Cancer study, a combination of BRAF inhibitor BRAFTOVI® (Encorafenib) and EGFR antagonist ERBITUX® (Cetuximab), with or without concomitant MEK inhibition improved Response Rates, Overall Survival and Progression Free Survival in patients with metastatic CRC with a BRAF V600E mutation. The FDA approved this doublet therapy in 2020 for this patient group. Despite this improved efficacy, a significant percentage of patients do not respond this therapy and among those who respond, the responses noted in CRC are still not as robust as has been in BRAF-mutant metastatic melanomas treated with anti-BRAF therapy. This suggests that there may be other factors modulating treatment response, including molecular determinants, that need to be identified, to optimize clinical management of these patients.

BRAF V600E mutated tumors in CRC are also associated with specific molecular features, including a low frequency of APC mutations and a high rate of mutations in the tumor suppressor gene RNF43 (Ring Finger Protein 43). RNF43 is a E3 ubiquitin ligase which negatively regulates Wnt signaling by inducing degradation of the Wnt receptors. It has been postulated that the a cross-talk between the MAPK and WNT signaling pathways may modulate the antitumor activity of anti-BRAF/EGFR therapy.

The researchers in this study sought to explore which genes were enriched for somatic mutations in responder and non-responder groups, among patients with BRAF V600E mutant CRC, treated with anti-BRAF/EGFR combination therapy. This study included 166 patients (N=166) with BRAF V600E mutant CRC of whom 98 patients received treatment with anti-BRAF/EGFR combination therapy (N=46 in the Discovery cohort and N=52 in the Validation cohort). The Control cohort (N=68) consisted of BRAF V600E mutant CRC patients treated with chemotherapy with or without antiangiogenic therapy, and were not exposed to anti-BRAF therapy. Whole-Exome Sequencing (WES) and/or targeted gene sequencing was performed on baseline tumor and/or plasma cell-free DNA (cfDNA) samples of all included patients, and over 20,000 genes were analyzed.

It was noted that RNF43 mutations were identified in 29% of BRAF V600E-mutated MicroSatellite-Stable (MSS) metastatic CRC tumors, and this finding was strongly associated with a clinical response to anti-BRAF/EGFR-based combination therapy. When compared to BRAF V600E-mutated, MicroSatellite-Stable metastatic CRC patients without the RNF43 mutation (RNF43 wild-type), patients with BRAF V600E-mutated, MicroSatellite-Stable metastatic CRC carrying a RNF43 mutation had a Response Rate of 72.7% versus 30.8% (P=0.03), longer median Progression Free Survival (10.1 months versus 4.1 months, HR=0.30; P=0.01) and longer median Overall Survival (13.6 months versus 7 months, HR=0.26; P=0.008). Conversely, the predictive value of RNF43 mutations seen in MicroSatellite-Stable tumors was not observed in MicroSatellite Instability (MSI)-High tumors.

The researchers concluded that these findings suggest that RNF43 may be a potential stratification biomarker that could help with decision making, in patients with MicroSatellite-Stable, BRAF V600E–mutant metastatic Colorectal cancer. They added that RNF43 gene may be a predictive biomarker of a response to treatment with anti-BRAF/EGFR combination therapy in this patient group.

RNF43 mutations predict response to anti-BRAF/EGFR combinatory therapies in BRAF V600E metastatic colorectal cancer. Elez, E, Ros J, Fernandez J, et al. Nature Medicine 2022;28:2162–2170.

Late Breaking Abstract – ASCO 2022: FOLFOXIRI Plus Bevacizumab in Unresectable Colorectal Cancer with Liver Metastases

RR

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 151,030 new cases of CRC will be diagnosed in the United States in 2022 and about 52,580 patients are expected to 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 include Oxaliplatin or Irinotecan, in combination with a Fluoropyrimidine and Leucovorin (FOLFOX or FOLFIRI), along with a VEGF targeting agent such as Bevacizumab. 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 and do not respond as 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. Colorectal cancer patients with unresectable liver-only metastases at the time of initial presentation may potentially be cured, after downsizing of metastases by neoadjuvant systemic therapy. However, the optimal neoadjuvant induction regimen has not been defined.

CAIRO5 is a prospective, randomized, multicentre, Phase III trial, conducted to investigate the optimal systemic induction therapy for patients with initially unresectable, liver-only colorectal cancer metastases. In this study, 294 patients were randomized to receive either FOLFOX or FOLFIRI plus Bevacizumab (N=148), or FOLFOXIRI plus Bevacizumab (N=146) for up to 12 cycles. Bevacizumab was given at a dose of 5 mg/kg IV. FOLFOX/FOLFIRI regimen consisted of either Oxaliplatin 85 mg/m2 IV or Irinotecan 180 mg/m2 IV, given along with Leucovorin 400 mg/m2 IV over 120 minutes, 5-Flourouracil (5-FU) 400 mg/m2 IV, followed by 5-FU 2400 mg/m2 given as an IV infusion over 46 hours. FOLFOXIRI regimen consisted of Oxaliplatin 85 mg/m2 IV, Irinotecan 165 mg/m2 IV, given along with Leucovorin 400 mg/m2 IV over 120 minutes, followed by 5-FU 3200 mg/m2 given as an IV infusion over 46 hours. Treatment was given every 2 weeks for a maximum of 12 cycles, followed by 5-FU, Leucovorin and Bevacizumab maintenance until disease progression. Enrolled patients had metastatic CRC with previously untreated liver-only metastases, (un)resectability status was prospectively assessed by a central panel consisting of radiologists and liver surgeons, according to predefined criteria, and patients were assessed for resectability every 2 months. Eligible patients had right-sided primary tumor and/or RAS or BRAF V600E mutated tumor. Both treatment groups were well balanced. The median age was 63 years, 41% had right-sided primary tumor, 86% of tumors had RAS mutation, 7% had BRAF V600E mutation, 5% had prior adjuvant chemotherapy, the median number of colorectal liver metastases was 12, and 87% had potentially resectable colorectal metastases. Patients were stratified by potentially resectable versus permanently unresectable colorectal liver metastases, BRAFV600E mutation, sidedness and choice of Irinotecan versus Oxaliplatin. The Primary endpoint was Progression Free Survival (PFS). Secondary endpoints included R0/1 resection, Overall Survival (OS), Overall Response Rate (ORR), toxicity, pathologic response and postoperative morbidity.

At a median follow up of 41 months, the median PFS was 9.0 months with doublet regimen FOLFOX/FOLFIRI plus Bevacizumab versus 10.6 months with the triplet regimen of FOLFOXIRI plus Bevacizumab. (HR=0.74; P=0.02). The ORR was 32% in the FOLFOX/FOLFIRI plus Bevacizumab group versus 52.1% in the FOLFOXIRI plus Bevacizumab group (P<0.001), R0/1 resection/ ablation rates were 37.4% versus 51.4% (P=0.02), and postoperative complications occurred in 38.2% versus 51.2% (P=0.14), respectively. Overall Survival data was immature at the time of data cutoff. Grade 3 or more adverse events, including neutropenia and diarrhea, were more common in the FOLFOXIRI plus Bevacizumab group.

It was concluded that in patients with initially unresectable colorectal cancer liver metastasis and right-sided and/or RAS or BRAF-mutated primary tumor, the triplet regimen of FOLFOXIRI plus Bevacizumab resulted in superior Progression Free Survival, a higher Objective Response Rate, and a greater chance for R0/R1 hepatic metastasectomy with or without ablation, compared to doublet chemotherapy with FOLFOX or FOLFIRI plus Bevacizumab. This benefit with the triplet regimen was achieved at the cost of increased toxicity, suggesting that careful patient selection should be made for the triplet regimen.

FOLFOXIRI + bevacizumab versus FOLFOX/FOLFIRI + bevacizumab in patients with initially unresectable colorectal liver metastases (CRLM) and right-sided and/or RAS/BRAFV600E-mutated primary tumor: Phase III CAIRO5 study of the Dutch Colorectal Cancer Group. Punt CJA, Bond MJG, Bolhuis K, et al. J Clin Oncol. 2022;40(suppl 17):LBA3506.

Late Breaking Abstract – ASCO 2022: Panitumumab Combined with mFOLFOX6 Improves Overall Survival in Left-Sided RAS Wild-Type Metastatic Colorectal Cancer

RR

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 151,030 new cases of CRC will be diagnosed in the United States in 2022 and about 52,580 patients are expected to 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 include Oxaliplatin or Irinotecan, in combination with a Fluoropyrimidine and Leucovorin (FOLFOX or FOLFIRI), along with a VEGF targeting agent such as Bevacizumab or EGFR targeting agents such as Cetuximab and Panitumumab. However numerous studies have failed to clearly establish that any of these combination regimens would be superior for any given patient based on clinical factors. Nonetheless, majority of patients with metastatic colorectal cancer receive FOLFOX-based first line treatment in the US. 

A retrospective evaluation from the Phase III 80405 clinical trial which included data from 1,025 patients with KRAS wild-type disease, concluded that the biology of tumors originating in the right colon may be different from those originating in the left colon, with Cetuximab showing superiority over Bevacizumab, when combined with chemotherapy, in KRAS wild-type patients with left-sided colon cancer. (J Clin Oncol 34, 2016: suppl; abstr 3504).

Panitumumab (VECTIBIX®) is a human IgG2 kappa monoclonal antibody, that targets and antagonizes Epidermal Growth Factor Receptor (EGFR). The PARADIGM Trial is a multicenter, open-label, prospective, Phase III study conducted in Japan, to evaluate the efficacy and superiority of mFOLFOX6 plus Panitumumab compared to mFOLFOX6 plus Bevacizumab, in the first line treatment of chemotherapy-naïve patients with RAS wild type (KRAS/NRAS gene) metastatic colorectal cancer and left-sided primary tumors (descending colon, sigmoid colon, and rectum). In this first prospective randomized study, a total of 400 patients received Panitumumab and 402 received Bevacizumab. Both groups received mFOLFOX6. Most of the patients had left sided tumors (N=614) of whom 312 patients received Panitumumab with chemotherapy, whereas 292 patients received Bevacizumab with chemotherapy. The Primary endpoint of Overall Survival (OS) was hierarchically tested in patients with left-sided tumors, followed by evaluation in the entire study population. Key Secondary endpoints included Progression Free Survival (PFS), Objective Response Rate (ORR), and curative resection (R0) rate. Overall Survival in patients with left-sided tumors was analyzed after a median follow up of 61 months.

The study met its Primary endpoint and Panitumumab in combination with mFOLFOX6 significantly improved median Overall Survival, compared to Bevacizumab plus mFOLFOX6 in the left-sided tumor population, with a 18% lower risk of death (37.9 months versus 34.3 months; HR=0.82; P=0.031). When the data was subsequently analyzed for the entire study group, the OS benefit also significantly favored Panitumumab combination over Bevacizumab combination (median 36.2 months versus 31.3 months; HR=0.84; P=0.030). This difference however appears to be driven by the left-sided tumor population, as there was no significant OS improvement seen for patients with right-sided tumors in an exploratory analysis (median 20.2 months versus 23.2 months; HR=1.09).

There was no significant difference in the median PFS between treatment groups in the population with left-sided tumors and the median PFS was 13.7 months with Panitumumab combination and 13.2 months with Bevacizumab combination (HR=0.98). However, both Objective Response Rate and curative (R0) resection rate was higher in the Panitumumab group compared with Bevacizumab group, in the population with left-sided tumors. The Objective Response Rate was 80.2% versus 68.6%, the curative (R0) resection rate 18.3% versus 11.6% and the median duration of response was 13.1 versus 11.2 months respectively. Treatment with Panitumumab, resulted in more skin, mucosal and nail toxicities, commonly associated with EGFR inhibitors, and no new safety signal were observed.

It was concluded that in this first and largest randomized first line study comparing the efficacy of different targeted therapies in combination with standard doublet chemotherapy based on tumor sidedness, Panitumumab in combination with mFOLFOX6 significantly improved Overall Survival, resulted in a higher Objective Response Rate and a higher curative resection rate, in patients with RAS wild-type and left-sided metastatic colorectal cancer, compared with patients who received Bevacizumab plus mFOLFOX6. These findings emphasize the importance of comprehensive biomarker testing, as well as taking into consideration tumor location, in patients with metastatic colorectal cancer.

Panitumumab (PAN) plus mFOLFOX6 versus bevacizumab (BEV) plus mFOLFOX6 as first-line treatment in patients with RAS wild-type (WT) metastatic colorectal cancer (mCRC): Results from the phase 3 PARADIGM trial. Yoshino T, Watanabe J, Shitara K, et al. DOI:10.1200/JCO.2022.40.17_suppl.LBA1 Journal of Clinical Oncology 40, no. 17_suppl (June 10, 2022) LBA1.