[Targeting HER2 in colorectal cancer]. / Cibler HER2 dans le cancer colorectal.

Among the molecular subgroups of interest in metastatic colorectal cancer (mCRC), innovations are underway for tumors with overexpression of HER2 (Human Epidermal Growth Factor Receptor 2). Overexpression of the HER2 protein concerns 2 to 5% of CRC at any stage mainly located in the distal colon and rectum. Diagnosis is based on immunohistochemistry, in situ hybridization with appropriate criteria for colorectal localization, and molecular biology (NGS: next-generation sequencing). Overexpression of HER2 is a predictive factor for resistance to treatments targeting EGFR which are indicated in the case where the tumor is wild-type RAS. It seems to be associated with a poor prognosis of mCRC with a higher risk of brain metastasis. Regarding treatments targeting HER2, no randomized controlled phase III has been published to date. However, several combinations have been evaluated in phase II with clinically meaningful objective response rates: trastuzumab-deruxtecan (45%), trastuzumab-tucatinib (46%), trastuzumab-pyrotinib (45%), trastuzumab-pertuzumab (30%) ou trastuzumab-lapatinib (30%). In this literature review, we present here the current state of knowledge on the diagnostic methods of HER2 overexpression in CRC, the main clinical, molecular and prognostic characteristics, and the efficacy results of the different therapeutic combinations for the patients with HER2 overexpressed mCRC. This justifies, despite the lack of marketing authorization in France and in Europe for agents targeting HER2 in CRC, the systematic evaluation of the HER2 status, as recommended in particular by the NCCN (National Comprehensive Cancer Network).

Reevaluating Disease-Free Survival as an Endpoint vs Overall Survival in Stage III Adjuvant Colon Cancer Trials.

BACKGROUND: Disease-free survival (DFS) with a 3-year median follow-up (3-year DFS) was validated as a surrogate for overall survival (OS) with a 5-year median follow-up (5-year OS) in adjuvant chemotherapy colon cancer (CC) trials. Recent data show further improvements in OS and survival after recurrence in patients who received adjuvant FOLFOX. Hence, reevaluation of the association between DFS and OS and determination of the optimal follow-up duration of OS to aid its utility in future adjuvant trials are needed. METHODS: Individual patient data from 9 randomized studies conducted between 1998 and 2009 were included; 3 trials tested biologics. Trial-level surrogacy examining the correlation of treatment effect estimates of 3-year DFS with 5 to 6.5-year OS was evaluated using both linear regression (RWLS2) and Copula bivariate (RCopula2) models and reported with 95% confidence intervals (CIs). For R2, a value closer to 1 indicates a stronger correlation. RESULTS: Data from a total of 18 396 patients were analyzed (median age = 59 years; 54.0% male), with 54.1% having low-risk tumors (T1-3 and N1), 31.6% KRAS mutated, 12.3% BRAF mutated, and 12.4% microsatellite instability high or deficient mismatch repair tumors. Trial-level correlation between 3-year DFS and 5-year OS remained strong (RWLS2 = 0.82, 95% CI = 0.67 to 0.98; RCopula2 = 0.92, 95% CI = 0.83 to 1.00) and increased as the median follow-up of OS extended. Analyses limited to trials that tested biologics showed consistent results. CONCLUSIONS: Three-year DFS remains a validated surrogate endpoint for 5-year OS in adjuvant CC trials. The correlation was likely strengthened with 6 years of follow-up for OS.

Microsatellite Instability in Patients With Stage III Colon Cancer Receiving Fluoropyrimidine With or Without Oxaliplatin: An ACCENT Pooled Analysis of 12 Adjuvant Trials.

PURPOSE: In patients with stage III colon cancer (CC) whose tumors demonstrate microsatellite instability (MSI), the efficacy of adjuvant fluoropyrimidine (FP) with or without oxaliplatin has not been clearly demonstrated and the prognostic value of MSI remains uncertain. MATERIALS AND METHODS: Individual patient data from the ACCENT database were used to evaluate the effect of FP with or without oxaliplatin on disease-free survival (DFS) and overall survival (OS) among patients with MSI stage III CC and the prognostic value of MSI in patients treated with FP plus oxaliplatin, by stratified Cox models adjusted for demographic and clinicopathological factors. RESULTS: MSI status was available for 5,457 patients (609 MSI, 11.2%; 4848 microsatellite stable [MSS], 88.8%) from 12 randomized clinical trials (RCTs). Oxaliplatin significantly improved OS of MSI patients from the two RCTs testing FP with or without oxaliplatin (n = 185; adjusted hazard ratio [aHR] = 0.52, 95% CI, 0.28 to 0.93). Among the 4,250 patients treated with FP plus oxaliplatin (461 MSI and 3789 MSS), MSI was associated with better OS in the N1 group compared with MSS (aHR = 0.66; 95% CI, 0.46 to 0.95) but similar survival in the N2 population (aHR = 1.13; 95% CI, 0.86 to 1.48; P interaction = .029). The main independent prognosticators of MSI patients treated with FP plus oxaliplatin were T stage (aHR = 2.09; 95% CI, 1.29 to 3.38) and N stage (aHR = 3.57; 95% CI, 2.32 to 5.48). Similar results were observed for DFS in all analyses. CONCLUSION: Adding oxaliplatin to FP improves OS and DFS in patients with MSI stage III CC. Compared with MSS, MSI patients experienced better outcomes in the N1 group but similar survival in the N2 group.

Impact of the IDEA Collaboration Study Results on Clinical Practice in France for Patients With Stage III Colon Cancer: A National GERCOR - PRODIGE Survey.

BACKGROUND: The IDEA collaboration showed that the type and duration of adjuvant chemotherapy in stage III colon cancer (CC) could be adjusted according to the schedule of chemotherapy and the level of risk. We aimed at evaluating the implementation of IDEA's results in real-life practice for stage III CC. MATERIAL AND METHODS: All clinicians registered in the French oncology cooperative groups GERCOR, FFCD, and UNICANCER GI mailing lists were invited to participate to an online anonymized nationwide survey from January 30, 2019 to March 31, 2019. Proportions were compared using the χ2 test. RESULTS: A total of 213 physicians answered the survey. Of these, 173 (81%) considered that 3 months of adjuvant chemotherapy was the new standard of care for low-risk (pT1-3/N1) stage III CC, and 99% considered that 6 months remained the standard of care for high-risk (pT4 and/or pN2) stage III CC. In patients under 70 years, capecitabine and oxaliplatin (CAPOX) for 3 months was prescribed by 74% of the participants in low-risk CC, whereas 6 months of 5-fluorouracil, leucovorin, and oxaliplatin (FOLFOX) was preferred for high-risk CC in 94% of cases. For patients over 70 years with good performance status and no comorbidities, 172 (81%) physicians prescribed oxaliplatin-based chemotherapy for low-risk CC (3 months, 144 of 172%; 88%), and 200 (94%) physicians prescribed oxaliplatin-based adjuvant chemotherapy for high-risk CC (6 months, 199 of 200%; 99.5%). CONCLUSIONS: The IDEA results have been practice-changing as French physicians have implemented 3 months of CAPOX for patients with low-risk stage III CC, substituting from 6 months of FOLFOX, which remains the preferred regimen for high-risk patients.