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Background Combination irinotecan and cetuximab is approved for irinotecan-refractory metastatic colorectal cancer (mCRC). It is unknown if adding bevacizumab improves outcomes. Patients and Methods In this multicenter, randomized, double-blind, placebo-controlled phase II trial, patients with irinotecan-refractory RAS- wildtype mCRC and no prior anti-EGFR therapy were randomized to cetuximab 500 mg/m2, bevacizumab 5 mg/kg, and irinotecan 180 mg/m2 (or previously tolerated dose) (CBI) versus cetuximab, irinotecan, and placebo (CI) every 2 weeks until disease progression or intolerable toxicity. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival (OS), objective response rate (ORR), and adverse events (AEs). Results The study closed early after the accrual of 36 out of a planned 120 patients due to changes in funding. Nineteen patients were randomized to CBI and 17 to CI. Baseline characteristics were similar between arms. Median PFS was 9.7 versus 5.5 months for CBI and CI, respectively (1-sided log-rank P =.38; adjusted hazard ratio [HR] = 0.64; 95% confidence interval [CI], 0.25-1.66). Median OS was 19.7 versus 10.2 months for CBI and CI (1-sided log-rank P =.02; adjusted HR = 0.41; 95% CI, 0.15-1.09). ORR was 36.8% for CBI versus 11.8% for CI (P =.13). Grade 3 or higher AEs occurred in 47% of patients receiving CBI versus 35% for CI (P =.46). Conclusion In this prematurely discontinued trial, there was no significant difference in the primary endpoint of PFS between CBI and CI. There was a statistically significant improvement in OS in favor of CBI compared with CI. Further investigation of CBI for the treatment of irinotecan-refractory mCRC is warranted. Clinical Trial Registration: NCT02292758 [ABSTRACT FROM AUTHOR]

Recently, the American Society of Clinical Oncology (ASCO) and the European Society for Medical Oncology (ESMO) recommended that patients with epidermal growth factor receptor (EGFR)-expressing metastatic colorectal cancer could be treated with anti-EGFR monoclonal antibodies (mAbs) cetuximab and panitumumab only in absence of Rat-Sarcoma (RAS) mutations. In addition to the previously established biomarker Kirsten rat sarcoma viral oncogene homolog (KRAS) exon 2, cumulative evidence also shows that patients whose tumors harbor KRAS exons 3 or 4 and neuroblastoma rat-sarcoma viral oncogene homolog (NRAS) exons 2, 3, and 4 mutations are found unlikely to benefit from anti-EGFR treatment. In line with the resistance of RAS mutated (mt) tumors, treatment response in BRAFmt tumors may also be altered given their important role in the EGFR signaling pathway. However, BRAF is not recommended as predictive biomarker yet because the evidence for the impact of BRAF mutations on treatment outcome is considered insufficient. This article summarizes the evidence for the impact of BRAF mutations on treatment outcome of anti-EGFR mAbs. Based on a review of literature, eight meta-analyses were included that consistently show that patients with BRAF mutations have a lack of treatment benefit of anti-EGFR mAbs. After discussing the quality and quantity of available evidence, we conclude that evidence is stronger than suggested by ESMO and ASCO. Additionally, we highlight that the quality of evidence for BRAF is even higher than for extended RAS as a biomarker. We therefore advise ESMO and ASCO to reconsider BRAF status as a predictive biomarker for response. [ABSTRACT FROM AUTHOR]

Introduction. A KRAS mutation represented the first genomic biomarker to predict lack of benefit from anti-epidermal growth factor receptor (EGFR) antibody therapy in advanced colorectal cancer (CRC). Expanded RAS testing has further refined the treatment approach, but understanding of genomic alterations underlying primary and acquired resistance is limited and further study is needed. Materials and Methods. We prospectively analyzed 4,422 clinical samples from patients with advanced CRC, using hybrid- capture based comprehensive genomic profiling (CGP) at the request of the individual treating physicians. Comparison with prior molecular testing results, when available, was performed to assess concordance. Results. We identified a RAS/RAF pathway mutation or amplification in 62% of cases, including samples harboring KRAS mutations outside of the codon 12/13 hotspot region in 6.4% of cases. Among cases with KRAS non-codon 12/13 alterations for which prior test results were available, 79 of 90 (88%) were not identified by focused testing. Of 1,644 RAS/RAF wild-type cases analyzed by CGP, 31% harbored a genomic alteration (GA) associated with resistance to anti- EGFRtherapy in advanced CRC including mutations in PIK3CA, PTEN, EGFR, and ERBB2. We also identified other targetable GA, including novel kinase fusions, receptor tyrosine kinase amplification, activating point mutations, as well as micro-satellite instability. Conclusion. Extended genomic profiling reliably detects alterations associated with lack of benefit to anti-EGFR therapy in advanced CRC, while simultaneously identifying alterations potentially important in guiding treatment. The use of CGP during the course of clinical care allows for the refined selection of appropriate targeted therapies and clinical trials, increasing the chance of clinical benefit and avoiding therapeutic futility. [ABSTRACT FROM AUTHOR]

Background Cetuximab is often administered to patients with KRAS wild-type (KRAS-WT) metastatic colorectal cancer (mCRC), although resistance inevitably develops. We hypothesized that co-inhibition of the epidermal growth factor receptor (EGFR) with cetuximab and downstream cyclin-dependent kinases (CDK) 4/6 with palbociclib would be effective for anti-EGFR rechallenge in KRAS-WT mCRC. Methods We designed a single-arm, Simon's 2-stage, phase II trial of cetuximab and palbociclib in KRAS-WT mCRC treated with ≥2 prior lines of therapy. We report here on cohort B rechallenging patients with anti-EGFR-based therapy who had disease control of at least 4 months on prior anti-EGFR therapy. Primary endpoint was disease control rate (DCR) at 4 months. Results Ten evaluable patients were enrolled in this cohort. The 4-month DCR was 20%, which did not fulfill the prespecified 4-month DCR rate to continue. Median progression-free survival was 1.8 months and median overall survival was 6.6 months. Three patients had stable disease, although overall response rate was 0%. Most common treatment-related grades 3-4 adverse events were lymphopenia and leukopenia. Conclusion Selection of patients for anti-EGFR rechallenge using clinical criteria alone was insufficient to identify response to palbociclib + cetuximab. Additional biomarkers are needed to select anti-EGFR rechallenge and circulating tumor DNA (ctDNA) analysis is planned for samples collected in this study. (ClinicalTrials.gov Identifier: NCT03446157) [ABSTRACT FROM AUTHOR]

BACKGROUND: Survival of patients with metastatic colorectal cancer (mCRC) has been significantly improved with the introduction of the monoclonal antibodies targeting the vascular endothelial growth factor (VEGF) and the epidermal growth factor receptor (EGFR). Novel molecular-targeted agents such as aflibercept and regorafenib have recently been approved. The aim of this review is to summarize and assess the effects of molecular agents in mCRC based on the available phase II and III trials, pooled analyses, and meta-analyses/systematic reviews. METHODS: A systematic literature search was conducted using the meta-database of the German Institute of Medical Documentation and Information. Criteria of the Scottish Intercollegiate Guidelines Network were used to assess the quality of the controlled trials and systematic reviews/meta-analyses. RESULTS: Of the 806 retrieved records, 40 publications were included. For bevacizumab, efficacy in combination with fluoropyrimidine-based chemotherapy in first- and subsequent-line settings has been shown. The benefit of continued VEGF targeting has also been demonstrated with aflibercept and regorafenib. Cetuximab is effective with fluoropyrimidine, leucovorin, and irinotecan (FOLFIRI) in first-line settings and as a single agent in last-line settings. Efficacy for panitumumab has been shown with oxaliplatin with fluoropyrimidine in first-line settings, with FOLFIRI in second-line settings, and as monotherapy in last-line settings. Treatment of anti-EGFR antibodies is restricted to patients with tumors that do not harbor mutations in Kirsten rat sarcoma and in neuroblastoma RAS. CONCLUSION: Among various therapeutic options, the future challenge will be a better selection of the population that will benefit the most from specific anti-VEGF or anti- EGFR treatment and a careful consideration of therapy sequence. [ABSTRACT FROM AUTHOR]

Preclinical and experimental data in vivo indicate that Lethal-7 (Let-7) microRNA downregulates KRAS with anti-tumor effects in the presence of activating KRAS mutations. We quantified the Let-7a isoform in KRAS-mutated colorectal carcinomas from patients who received salvage cetuximab plus irinotecan. The study population was retrospectively identified among metastatic colorectal cancer patients who underwent third-line therapy with cetuximab plus irinotecan in a period when only epidermal growth factor receptor (EGFR) expression was required for anti-EGFR therapy. In 59 patients harboring KRAS mutations, Let-7a levels were analyzed for association with overall survival (OS) and progression-free survival (PFS) times. An exploratory subgroup analysis was performed using the rs61764370 (LCS6 T>G) polymorphism that experimentally impairs Let-7 binding to KRAS mRNA. In the whole group, higher Let-7a levels were significantly associated with better survival outcomes. For the primary OS endpoint, the multivariate hazard ratio was 0.82 (95% confidence interval, 0.73--0.91; p=.01). The same findings with an accentuated positive effect of high Let-7a levels on both OS and PFS times were observed in an exploratory analysis of the 45 wild-type LCS6 patients (excluding 14 carriers of the LCS6 G allele variant). All survival associations were confirmed after excluding patients with KRAS codon 13 mutations. Among the clinicopathologic features, high Let-7a levels were associated with grade 2--3 skin toxicity (p = .002). In patients with KRAS mutations, Let-7a analysis may serve to identify subgroups of patients who may still benefit from EGFR inhibition and this may open up new perspectives for alternative treatment strategies. [ABSTRACT FROM AUTHOR]

Single-agent cetuximab is safe and active in elderly patients with advanced colorectal cancer (CRC). A cetuximab-capecitabine combination has not previously been tested in elderly patients with advanced CRC. Material and Methods. Sixty-six patients with advanced CRC were treated with cetuximab as a 400 mg/m2 i.v. infusion followed by 250 mg/m2 i.v. weekly plus capecitabine at a dose of 1,250 mg/m2 every 12 hours. After the inclusion of 27 patients, the protocol was amended for safety reasons, reducing the dose of capecitabine to 1,000 mg/m2 every 12 hours. Thirty-nine additional patients were treated with the reduced dose of capecitabine. Results. The overall response rate was 31.8%. KRAS status was determined in 58 patients (88%). Fourteen of 29 patients with wild-type KRAS tumors responded (48.3%; 95% confidence interval [CI], 29.4%-67.5%), compared with six of 29 patients with mutant KRAS tumors (20.7%; 95% CI, 8.0%-39.7%). The median progression-free survival (PFS) interval was 7.1 months. The median PFS interval for patients whose tumors were wild-type KRAS was significantly longer than for those with mutant KRAS tumors (8.4 months versus 6.0 months; p = .024). The high incidence of severe paronychia (29.6%) declined (7.7%) after capecitabine dose adjustment. Conclusions. Cetuximab plus capecitabine at a dose of 1,000 mg/m2 every 12 hours may be an alternative to more aggressive regimens in elderly patients with advanced wild-type KRAS CRC. [ABSTRACT FROM AUTHOR]

Background. Cetuximab was demonstrated by clinical trials to improve response rate and survival of patients with metastatic and nonresectable colorectal cancer or carcinoma of the head and neck. Appropriate management of skin toxicity associated with epidermal growth factor receptor inhibitor (EGFR-i) therapy is necessary to allow adequate drug administration and to improve quality of life and outcomes. Methods. A group of Italian Experts produced recommendations for skin toxicity management using the RAND/UCLA Appropriateness Method. Statements were generated on the basis of a systematic revision of the literature and voted twice by a panel of 40 expert physicians; the second vote was preceded by a meeting of the panelists. Results. Skin toxicity included skin rash, skin dryness, pruritus, paronychia, hair abnormality, and mucositis. Recommendations for prophylaxis and therapeutic interventions for each type of toxicity were proposed. Conclusions. Interventions that were considered appropriate to improve compliance and outcomes of cancer patients treated with EGFR-i were identified. [ABSTRACT FROM AUTHOR]

Targeted biologic agents have an established role in treating metastatic colorectal cancer (mCRC). Bevacizumab, a recombinant monoclonal antibody against the vascular endothelial growth factor ligand is approved by the U.S. Food and Drug Administration (FDA) for bevacizumab-naïve patients. Cetuximab, a chimeric monoclonal antibody (mAb) against the epidermal growth factor receptor (EGFR) is FDA approved as a single agent, or in combination with irinotecan, in both irinotecan-naïve and refractory patients, and has additional efficacy in combination with oxaliplatin. Panitumumab, a fully human EGFR mAb, is FDA approved as a single agent in refractory patients but has additional efficacy in combination with chemotherapy. After reaching a temporary therapeutic plateau of FDA-approved agents for the treatment of mCRC, pivotal results have developed that critically affect the care for these patients. Correlative data from randomized trials of EGFR inhibitors across disease settings have demonstrated higher response rates, specifically for patients with wild-type K-RAS tumors. The interpretation of the B-RAF mutation and other molecular markers may further define the appropriateness of anti-EGFR therapy. Recent literature revealed that the first-line use of combined anti-EGFR therapy plus bevacizumab resulted in inferior outcomes and additional toxicities. Furthermore, the role of biologic agents for locally advanced colon cancer cannot be advocated at this time. With impending changes in the health care system, the economic impact of mAbs will continue to be scrutinized. Hence, as the significance of molecular markers continues to develop, their role as it pertains to the appropriate use of biologic agents in the treatment of mCRC will continue to evolve. The Oncologist 2010;15:73-84 [ABSTRACT FROM AUTHOR]

The introduction of novel agents targeted to specific molecular features of cancer cells promises more options and marked improvements in efficacy for treatment of colon cancer. This overview of clinical studies describes the effects of administering the targeted agents bevacizumab, cetuximab, and panitumumab, also known as monoclonal antibodies, to treat metastatic colorectal cancer (mCRC) patients. All three targeted agents have been approved for use by the U.S. Food and Drug Administration and the European Agency for the Evaluation of Medicinal Products. Bevacizumab has been shown to extend survival when used in combination with irinotecan and 5-fluorouracil--based chemotherapy, and the addition of cetuximab to irinotecan and 5-fluorouracil--based chemotherapy overcomes irinotecan resistance. Cetuximab and panitumumab are both efficacious among refractory mCRC patients with wildtype KRAS tumors. Other targeted agents, for example, the tyrosine kinase inhibitors erlotinib, gefitinib, sunitinib, and vatalanib (PTK787/ZK 222584), are currently in various stages of clinical development. [ABSTRACT FROM AUTHOR]

Purpose. To determine the optimal dose of the antiepidermal growth factor receptor (EGFR) monoclonal antibody cetuximab that can be safely administered in combination with a standard daily dose of erlotinib in patients with advanced solid malignancies. Patients and Methods. Patients with advanced solid malignancies who had failed standard chemotherapies received escalating doses of cetuximab without a loading dose (100, 200, 250 mg/m² i.v. weekly) in combination with a fixed dose of erlotinib (150 mg daily orally) until disease progression or unacceptable toxicity. Results. Twenty-two patients were treated, including 14 patients (64%) with non-small cell lung cancer. Twenty patients received combination treatment at the highest dose level for a median of 5.5 weeks (range, 1-31 weeks). One dose-limiting toxicity was observed: grade 3 skin rash. Overall, the most common adverse events (any grade, grade 3/4) were consistent with the safety profiles of the individual drugs: acneform rash (100%, 9%), diarrhea (77%, 5%), and hypomagnesemia (59%, 12%). Seven of 18 evaluable patients (38.9%) had stable disease lasting for a median of 16.6 weeks (range, 6.1-25.1 weeks). Conclusion. Dual EGFR inhibition with cetuximab and erlotinib is feasible; the observed toxicities were manageable and consistent with the safety profiles of the individual drugs. The recommended doses for phase II studies are 250 mg/m² i.v. weekly for cetuximab and 150 mg daily orally for erlotinib. [ABSTRACT FROM AUTHOR]

Over the past 10 years there has been a significant increase in the armamentarium of agents available for use in the treatment of advanced colorectal cancer (CRC).Among these new agents are two monoclonal antibodies targeting the epidermal growth factor receptor (EGFR): cetuximab, a mouse--human chimeric monoclonal antibody, and panitumumab, a fully human monoclonal antibody. Both are approved as monotherapy for the treatment of chemotherapy-refractory advanced CRC. Cetuximab is also indicated for use in combination with irinotecan. Here, we review 10 reports of phase II and III clinical studies of patients treated with panitumumab or cetuximab monotherapy. The clinical trials demonstrate similar efficacy profiles for advanced CRC patients treated with panitumumab and cetuximab monotherapy, with some differences in their adverse event profiles. In addition, the recent results of retrospective tumor KRAS gene mutational analyses in CRC patients treated with anti-EGFR monotherapy are reviewed. Data from the clinical trials reviewed here clearly demonstrate that anti-EGFR monotherapy is an effective treatment modality for patients with chemotherapy-refractory advanced CRC. [ABSTRACT FROM AUTHOR]