Interim analysis of the phase II AVETUXIRI trial: Avelumab combined with cetuximab and irinotecan for treatment of refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC)

3595

Background: Immune checkpoint inhibitors demonstrated poor efficacy in MSS mCRC. Cetuximab (anti-EGFR inhibitor) could initiate, independently from RAS mutation, an immunogenic tumor cell death and mediate antitumor immune response. In this trial, we aim to explore the clinical efficacy and safety of avelumab (anti-PDL1) combined with cetuximab and irinotecan for treatment refractory MSS mCRC and to understand its mechanisms of action through associated translational research. Methods: AVETUXIRI trial (NCT03608046) enrols MSS, chemorefractory (fluoropyrimidine, oxaliplatin, irinotecan and anti-EGFR treatment if RAS wt tumor) mCRC patients in 2 cohorts (A: RAS-wt, n = 10 – B: RAS-mut, n = 13). Primary endpoints are safety and tumor response rate ((i)RECIST1.1). Secondary endpoints include disease control rate (DCR), progression-free survival (PFS) and overall survival (OS). According to a Simon 2-stage design, 23 patients have been included in the first stage of the trial. Multiplex immunofluorescence and RNA sequencing were realized on metastasis biopsies performed before, during and after the treatment. Densities of CD3+ (T cells) and CD8+ (cytotoxic) were quantified and analyzed with to generate an immunoscore (IS). RNA-seq data was used to perform differential expression analysis (DESeq2), gene set enrichment analysis (GSEA), deconvolution analysis (ConsensusTME) and gene ontology analysis (GO). Results:: No unexpected safety signals were observed. 3/10 tumor responses were observed in cohort A, 0/13 in cohort B. DCR was 60.0% and 61.5% in cohort A and B, respectively. 6-months PFS and 12-months OS rates were respectively 40.0% and 50.0% (cohort A) and 38.5% and 46.2% (cohort B). Independently of RAS mutation, patients with a high IS (metastasis biopsy, baseline) had significantly higher tumor shrinkage (OR = 18.67 p = 0.019), median PFS (6.9 vs 3.4 months; HR = 0.16, p = 0.002) and median OS (13.7 vs 7.9 months, HR = 0.26, p = 0.009). Similarly, tumor shrinkage and survival outcome (PFS > 6 months, OS > 12 months) were associated with upregulation of an adaptive immune response signature (including Th1, chemokine, adhesion molecules, immune checkpoints and T-cell activation genes, p. adj = 0.009) and the GSEA hallmark of epithelial to mesenchymal transition (p. adj = 0.045). Few modifications of IS and gene expression profiles were observed on the different metastasis biopsies performed overtime in the included patients. Conclusions: AVETUXIRI met its preliminary primary efficacy endpoint for RAS-wt mCRC pts, justifying its current continuation. Encouraging survival data observed in RAS-mut cohort allow the opening of a new cohort (PFS as primary endpoint). IS and adaptive immune response signature evaluated on metastases biopsies were associated with treatment efficacy and survival. Clinical trial information: NCT03608046.

Homogeneity of pathological response (PR) and histopathological growth pattern (HGP) in resected colorectal liver metastases (CRLM) are associated with favorable survival outcome after surgery

3596

Background: Surgical resection of CRLM aims to maximize patient survival. However, recurrence rates remain high post-surgery. We previously reported the prognostic relevance of tumor regression grading (TRG) and HGP of resected CRLM. Several studies reported the association of tumoral heterogeneity with anti-cancer drug resistance and prognosis. This study aims to explore tumoral heterogeneity for TRG and HGP in patients resected for CRLM and its prognostic implication. Methods: Tumor homogeneity for PR and HGP was evaluated in 2 independent cohorts. Cohort 1 included 57 patients (159 CRLMs) resected after chemotherapy/bevacizumab (prospective BEV-ONCO trial). Cohort 2 included 221 patients (582 CRLMs) operated after preoperative treatment or not. TRG (1 to 5 according complete to no response), HGP (desmoplastic, pushing, replacement or mixed) were evaluated for each CRLM. Max-TRG (higher TRG among all the CRLM) was used to define PR. Homogenous TRG (TRG-h) and HGP (HGP-h) was defined when all CRLMs had the same TRG or HGP pattern. HGP homogeneous desmoplastic (HGP-hd) was defined when all CRLM had a desmoplastic HGP. TRG-h, HGP-h and HGP-hd were combined into a homogeneity score (H-score: 0 to 3, 1 point given for each parameter and summed-up). Overall survival (OS for both cohorts), progression-free survival (PFS for cohort 1) and time to relapse (TTR for cohort 2) were estimated using the Kaplan–Meier method and compared by log-rank tests. Cox proportional hazard models were used for univariate and multivariate analyses. Results: Patient and disease characteristics were comparable in both cohorts excepted for preoperative treatment. In cohort 1, TRG-h and HGP-h were significantly associated with a longer PFS (HR = 0.21; 95CI:0.10-0.43, p < 0.001; HR = 0.27; 95CI = 0.14-0.54, p < 0.001) and better OS (HR = 0.23; 95CI = 0.07-0.70, p = 0.010; HR = 0.32; 95CI = 0.10-0.93, p = 0.037). Interestingly, the same significant results were observed in cohort 2 for TTR (TRG-h: HR = 0.60; 95CI = 0.43-0.85, p = 0.004; HGP-h: HR = 0.68; 95CI = 0.49-0.94, p = 0.017) and OS (TRG-h: HR = 0.51;95CI = 0.33-0.80, p = 0.003; HGP-h: HR = 0.63; 95CI = 0.41-0.97, p = 0.034). HGP-h reported a significant association with TRG-h, a Max-TRG < = 3, the absence of HGP replacement and mixed, a desmoplastic pattern, and the absence of sinusoidal obstruction syndrome in both cohorts. H-score was significantly associated with TTR (score 1-2: HR = 0.57; 95CI = 0.38-0.85, p = 0.004; score 3: HR = 0.4; 95CI = 0.24-0.64, p < 0.001) and OS (score 3: HR = 0.31; 95CI = 0.15-0.64, p < 0.001) in univariate analysis and with OS (HR = 0.74; 95CI = 0.59-0.94, p = 0.011) in multivariate analysis (cohort 2). Conclusions: TRG-h and HGP-h are strongly associated with patient’s survival. H-score could be an easy morphological and prognostic score to assess. Validation studies are needed.

Randomized Phase 2 Study Comparing Pathological Responses of Resected Colorectal Cancer Metastases after Bevacizumab with mFOLFOX6 or FOLFIRI (BEV-ONCO Trial)

Retrospective studies reported that preoperative oxaliplatin-based chemotherapy increased pathological response (PR) in patients resected for colorectal liver metastases (CRLM). This multicenter prospective randomized (1/1) phase II trial evaluated PR on resected CRLM after preoperative mFOLFOX6 (arm A) or FOLFIRI (arm B) + bevacizumab. The primary endpoint was the major pathological response rate (MPRR), defined as the percentage of patients presenting CRLMs with mean tumor regression grade (TRG) < 3. Secondary endpoints included safety, progression-free survival (PFS) and overall survival (OS). Out of 65 patients, 57 patients (28 and 29 in arm A/B) were resected for CRLM (one patient with lung metastases). Clinical and treatment characteristics were similar in both arms. One-month postoperative complications were 39.3%/31.0% in arm A/B (p = 0.585). MPRR and complete PR were 32.1%/20.7% (p = 0.379) and 14.3%/0.0% (p = 0.052) in arm A/B, respectively. PFS and OS were not different. Patients with PR among all CRLMs (max TRG ≤ 3; 43.8% of patients) had a lower risk of relapse (PFS: HR = 0.41, 95%CI = 0.204−0.840, p = 0.015) and a tendency towards better survival (OS: HR = 0.34, 95%CI = 0.104−1.114, p = 0.075). The homogeneity of PR was associated with improved PFS/OS. This trial fails to demonstrate a significant increase in MPRR in patients treated with mFOLFOX6-bevacizumab but confirms PR as an important prognostic factor.

Interim analysis of the AVETUXIRI Trial: Avelumab combined with cetuximab and irinotecan for treatment of refractory microsatellite stable (MSS) metastatic colorectal cancer (mCRC)—A proof of concept, open-label, nonrandomized phase IIa study

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Background: Immune checkpoint inhibitors have demonstrated poor efficacy in MSS mCRC. Previous research indicate that cetuximab (anti-EGFR chimeric monoclonal antibody) could initiate, independently from RAS mutation, an immunogenic tumor cell death and mediate antitumor immune response. In this trial, we aim to explore the clinical efficacy and safety of anti-PDL1 avelumab (AVE) combined with cetuximab (CET) and irinotecan (IRI) for treatment refractory MSS mCRC. Methods: AVETUXIRI (NCT03608046) is a multicenter academic study recruiting MSS, BRAFV600E wt, mCRC patients (pts) refractory to standard treatment (fluoropyrimidine, oxaliplatin, irinotecan and anti-EGFR treatment if RAS wt tumor) in 2 cohorts (cohort A: RAS wt – cohort B: RAS mut). In both cohorts, patients receive CET (400 mg/m2 W1, 250 mg/m2 W2, 500 mg/m2/2 weeks from W3), IRI (180 - 150 mg/m2/2 weeks from W1) and AVE (10 mg/kg/2 weeks starting from W3). Primary endpoints are overall response rate (ORR), defined as partial or complete response (PR or CR) according (i)RECIST1.1, and safety. Secondary endpoints include disease control rate (DCR), PFS and OS. Based on a Simon 2-stage design for ORR in each cohort (cohort A: P0=0.15, P1=0.33 / cohort B: P0=0.09, P1=0.25 / α = 0.1, β = 0.2 in both cohorts), 10 and 13 patients are required in the first stage of cohort A and B respectively. At least 2 pts have to reach PR or CR in each cohort to allow the continuation of the trial in the 2nd stage. Results: Between Oct 2018 and Jan 2020, 23 patients (median age 62 y-old, 86.9% male 78.3% left-sided, 91.3% synchronous mCRC) have been included in the first stage of the trial. No major or unexpected safety events were observed. 21.7% (5/23) of pts presented grade 3 diarrhea, all related to IRI, with complete resolution after IRI dose reduction or interruption. A reduced starting dose of IRI (150 mg/m2) was amended (09/2019) for the last included 8 pts without any grade 3-4 diarrhea occurrence. Grade 1-2 hypothyroidism was the only immune-related side effect. 3 PR were observed in cohort A and none in cohort B. DCR was 60.0% (6/10) and 61.5% (8/13) in cohort A and B respectively. Median PFS and OS were respectively 4.2 and 12.7 months (cohort A) and 3.8 and 14.0 months (cohort B). 6 months-PFS rate was 40.0% and 38.5% in cohort A and B. 12 months-OS rate was 53.3% and 57.7% in cohort A and B. The median follow-up of patients was 9.2 months. Conclusions: The AVETUXIRI trial met its primary efficacy endpoint for RAS wt mCRC pts justifying the study continuation in cohort A (2nd stage). No PR was observed in RAS-mut cohort. Nevertheless, encouraging data of DCR, PFS and OS observed in RAS mut cohort allow the opening of a new cohort for RAS-mut mCRC (cohort C) with PFS as primary endpoint. Clinical trial information: NCT03608046.

Randomized phase II studies comparing pathological responses observed on colorectal cancer metastases resected after preoperative treatment combining bevacizumab or cetuximab with FOLFOX or FOLFIRI

TPS795

Background: Even if the use of targeted therapies combined with chemotherapy has demonstrated increase response rate and survival benefit in non resectable metastatic colorectal cancer (mCRC), the administration of these combinations in frontline resectable disease is source of debate and optimal association is still unclear. Based on a retrospective analysis, we previously reported thatthe chemotherapy partner combined with VEGF or EGFR inhibitors influenced pathological responses (pR) on the resected colorectal cancer metastases (CRCM) with a significant advantage for oxaliplatin with anti-VEGF or irinotecan with anti-EGFR combinations. We aimed to design 2 parallel studies (BEV-ONCO, CET-ONCO) to prospectively precise optimal combination between oxaliplatin and irinotecan with bevacizumab or cetuximab before CRCM resection. Methods: The 2 studies are open label randomized multi-centric trials and concern mCRC patients with resectable disease in whom a preoperative treatment is considered. The primary objective is to assess the CRCM pR rate according the Tumor Regression Grade classification (Rubbia-Brandt) after allocated preoperative treatment (bevacizumab combined with FOLFOX vs. FOLFIRI without consideration of RAS/BRAF for BEV-ONCO trial (EUDRACT 2012-005376-34) and cetuximab associated with FOLFOX or FOLFIRI only for RAS/BRAF wild type tumor for CET-ONCO trial (EUDRACT 2012-005249-19)). According investigator’s choice, patient will received 3 to 6 treatment cycles before CRCM resection. Patient’s survival, safety, surgical complications and treatment associated liver-toxicity are secondary end-points. Up to 60 patients (30 per treatment group) will be randomised in each study (power: 80%, type I error of 5% to detect a difference in proportion of pR rate between FOLFOX or FOLFIRI association of 0.40). Formal comparison will not be done across studies. Translational research projects are ongoing (CRCM immune response, tumour specific genetic rearrangements as new specific biomarkers). Clinical trial information: NCT01858649 (BEV-ONCO); NCT01858662 (CET-ONCO). Clinical trial information: NCT01858649 (BEVONCO) NCT01858662 (CETONCO).