Translational analysis and final efficacy of the AVETUX trial - Avelumab, cetuximab and FOLFOX in metastatic colorectal cancer.

Introduction: In metastatic colorectal cancer (mCRC), the efficacy of immune checkpoint blockade (ICB) has so far been limited to patients with microsatellite instability high tumors (MSI-H). Unfortunately, most mCRC patients suffer from non-immunogenic microsatellite stable (MSS) tumors. Therefore, new combinatorial strategies are urgently needed to enhance the immunogenicity of MSS tumors to finally increase the number of patients benefiting from ICB. Methods: The AVETUX trial aimed to combine the PD-L1 antibody avelumab with the standard of care chemotherapy combination FOLFOX and the anti-EGFR antibody cetuximab. Furthermore, we performed a central radiological review of the pre- and on-treatment computed tomography scans to better define the individual response to treatment. Results and Discussion: In total, 43 patients were treated of which 39 patients were confirmed as RAS/BRAF wildtype in central tissue review and finally response evaluated. A final progression-free survival (PFS) of 11.1 (range: 0.8 to 22.3 months) and a herein updated final overall survival (OS) of 32.9 months (range: 0.8 to 47.1 months) was reached. We observed a strong median depth of response of 67.5% tumor shrinkage and deepness of response correlated significantly with survival. On the other hand, early tumor shrinkage was not an indicator of better outcome at a cut-off of 20% (median values). In a next step, we correlated the individual best radiological response with potential ICB response biomarkers and found that the clonality and diversity, but not frequency of tumor infiltrating lymphocytes (TiLs) and peripheral blood mononuclear cells (PBMCs), strongly correlated with response. In summary, we report the final overall survival of the AVETUX trial and propose T cell clonality and diversity as a potential marker to predict response to chemo-immunotherapy combinations in MSS mCRC by performing a central radiological review. Clinical Trial Registration: ClinicalTrials.gov, identifier (NCT03174405).

PD-L1 targeting and subclonal immune escape mediated by PD-L1 mutations in metastatic colorectal cancer.

BACKGROUND: In patients with microsatellite stable (MSS) metastatic colorectal cancer (mCRC), immune checkpoint blockade is ineffective, and combinatorial approaches enhancing immunogenicity need exploration. METHODS: We treated 43 patients with predominantly microsatellite stable RAS/BRAF wild-type mCRC on a phase II trial combining chemotherapy with the epidermal growth factor receptor antibody cetuximab and the programmed cell death ligand 1 (PD-L1) antibody avelumab. We performed next-generation gene panel sequencing for mutational typing of tumors and liquid biopsy monitoring as well as digital droplet PCR to confirm individual mutations. Translational analyses included tissue immunohistochemistry, multispectral imaging and repertoire sequencing of tumor-infiltrating T cells. Detected PD-L1 mutations were mechanistically validated in CRISPR/Cas9-generated cell models using qRT-PCR, immunoblotting, flow cytometry, complement-dependent cytotoxicity assay, antibody-dependent cytotoxicity by natural killer cell degranulation assay and LDH release assay as well as live cell imaging of T cell mediated tumor cell killing. RESULTS: Circulating tumor DNA showed rapid clearance in the majority of patients mirroring a high rate of early tumor shrinkage. In 3 of 13 patients expressing the high-affinity Fcγ receptor 3a (FcγR3a), tumor subclones with PD-L1 mutations were selected that led to loss of tumor PD-L1 by nonsense-mediated RNA decay in PD-L1 K162fs and protein degradation in PD-L1 L88S. As a consequence, avelumab binding and antibody-dependent cytotoxicity were impaired, while T cell killing of these variant clones was increased. Interestingly, PD-L1 mutant subclones showed slow selection dynamics reversing on avelumab withdrawal and patients with such subclones had above-average treatment benefit. This suggested that the PD-L1 mutations mediated resistance to direct antitumor effects of avelumab, while at the same time loss of PD-L1 reduced biological fitness by enhanced T cell killing limiting subclonal expansion. CONCLUSION: The addition of avelumab to standard treatment appeared feasible and safe. PD-L1 mutations mediate subclonal immune escape to avelumab in some patients with mCRC expressing high-affinity FcγR3a, which may be a subset experiencing most selective pressure. Future trials evaluating the addition of avelumab to standard treatment in MSS mCRC are warranted especially in this patient subpopulation. TRIAL REGISTRATION NUMBER: NCT03174405.

Outcomes based on age in the phase III METEOR trial of cabozantinib versus everolimus in patients with advanced renal cell carcinoma.

BACKGROUND: Cabozantinib improved progression-free survival (PFS), overall survival (OS) and objective response rate (ORR) compared with everolimus in patients with advanced renal cell carcinoma (RCC) after prior antiangiogenic therapy in the phase III METEOR trial (NCT01865747). Limited data are available on the use of targeted therapies in older patients with advanced RCC. METHODS: Efficacy and safety in METEOR were retrospectively analysed for three age subgroups: <65 (n = 394), 65-74 (n = 201) and ≥75 years (n = 63). RESULTS: PFS, OS and ORR were improved with cabozantinib compared with everolimus in all age subgroups. The PFS hazard ratios (HRs) were 0.53 (95% confidence interval [CI]: 0.41-0.68), 0.53 (95% CI: 0.37-0.77) and 0.38 (95% CI: 0.18-0.79) for <65, 65-74 and ≥75 years, respectively, and the OS HRs were 0.72 (95% CI: 0.54-0.95), 0.66 (95% CI: 0.44-0.99) and 0.57 (95% CI: 0.28-1.14). The ORR for cabozantinib versus everolimus was 15% vs 5%, 21% vs 2% and 19% vs 0%, respectively. No significant differences were observed in PFS or OS with age as a categorical or continuous variable. Grade III/IV adverse events (AEs) were generally consistent across subgroups, although fatigue, hypertension and hyponatraemia occurred more frequently in older patients treated with cabozantinib. Dose reductions to manage AEs were more frequent in patients receiving cabozantinib than in those receiving everolimus. Dose reductions and treatment discontinuation due to AEs were more frequent in older patients in both treatment groups. CONCLUSIONS: Cabozantinib improved PFS, OS and ORR compared with everolimus in previously treated patients with advanced RCC, irrespective of age group, supporting use in all age categories. Proactive dose modification and supportive care may help to mitigate AEs in older patients while maintaining efficacy.

Impact of primary tumour location and RAS/BRAF mutational status in metastatic colorectal cancer treated with first-line regimens containing oxaliplatin and bevacizumab: Prognostic factors from the AIO KRK0207 first-line and maintenance therapy trial.

BACKGROUND: The major prognostic relevance of primary tumour location (LPT) in advanced colorectal cancer was shown in large retrospective studies, but quantitative estimates are highly heterogeneous, and there is still limited information about its impact within the framework of biomarker-guided treatment strategies. Therefore, we analysed LPT in relation to other clinical and molecular parameters, based on mature survival data from the recent randomised AIO KRK0207 trial. METHODS: Patients uniformly received first-line induction treatment with a combination of bevacizumab, oxaliplatin and fluoropyrimidine. LPT was retrospectively determined using surgical reports, pathology reports and endoscopy reports. The prognostic analyses were performed using Kaplan-Meier estimations and log-rank tests, while hazard ratios (HRs) and multivariable results were derived from Cox models. RESULTS: Among 754 patients with unequivocal information on LPT, patients with left-sided tumours showed a median overall survival of 24.8 months compared with the right-sided cohort with 18.4 months (HR: 1.54, 95% confidence interval: 1.30-1.81, P < 0.0001). In a multivariable model, LPT proved to be the strongest prognosticator (HR 1.60), with performance status, number of metastatic sites, baseline carcinoembryonic antigen (CEA) and platelets independently retaining prognostic significance. In the subgroup of patients with known RAS/BRAF status (n = 567, 75%), a BRAF mutation showed the greatest unfavourable impact (HR 3.16). Although BRAF is strongly correlated to LPT, the latter remained a significant prognosticator in the BRAF wild-type subgroup. In contrast, no major impact of LPT was seen on tumours carrying RAS mutations. CONCLUSIONS: Within the framework of a uniform treatment strategy according to the current standards, LPT proved to have an important, although not solely dominating, relevance for survival prognosis. Its impact seems to be low in tumours with a RAS mutation. REGISTRATION: ClinicalTrials.govNCT00973609.

Maintenance strategies after first-line oxaliplatin plus fluoropyrimidine plus bevacizumab for patients with metastatic colorectal cancer (AIO 0207): a randomised, non-inferiority, open-label, phase 3 trial.

BACKGROUND: The definition of a best maintenance strategy following combination chemotherapy plus bevacizumab in metastatic colorectal cancer is unclear. We investigated whether no continuation of therapy or bevacizumab alone are non-inferior to fluoropyrimidine plus bevacizumab, following induction treatment with a fluoropyrimidine plus oxaliplatin plus bevacizumab. METHODS: In this open-label, non-inferiority, randomised phase 3 trial, we included patients aged 18 years or older with histologically confirmed, previously untreated metastatic colorectal cancer, Eastern Cooperative Oncology Group (ECOG) performance status of 0-2, adequate bone marrow, liver, and renal function, no pre-existing neuropathy greater than grade 1, and measurable disease, from 55 hospitals and 51 private practices in Germany. After 24 weeks of induction therapy with either fluorouracil plus leucovorin plus oxaliplatin or capecitabine plus oxaliplatin, both with bevacizumab, patients without disease progression were randomly assigned centrally by fax (1:1:1) to standard maintenance treatment with a fluoropyrimidine plus bevacizumab, bevacizumab alone, or no treatment. Both patients and investigators were aware of treatment assignment. Stratification criteria were response status, termination of oxaliplatin, previous adjuvant treatment with oxaliplatin, and ECOG performance status. At first progression, re-induction with all drugs of the induction treatment was a planned part of the protocol. Time to failure of strategy was the primary endpoint, defined as time from randomisation to second progression after maintenance (and if applicable re-induction), death, or initiation of further treatment including a new drug. Time to failure of strategy was equivalent to time to first progression for patients who did not receive re-induction (for any reason). The boundary for assessment of non-inferiority was upper limit of the one-sided 98·8% CI 1·43. Analyses were done by intention to treat. The study has completed recruitment, but follow-up of participants is ongoing. The trial is registered with ClinicalTrials.gov, number NCT00973609. FINDINGS: Between Sept 17, 2009, and Feb 21, 2013, 837 patients were enrolled and 472 randomised; 158 were randomly assigned to receive fluoropyrimidine plus bevacizumab, 156 to receive bevacizumab monotherapy, and 158 to receive no treatment. Median follow-up from randomisation is 17·0 months (IQR 9·5-25·4). Median time to failure of strategy was 6·9 months (95% CI 6·1-8·5) for the fluoropyrimidine plus bevacizumab group, 6·1 months (5·3-7·4) for the bevacizumab alone group, and 6·4 months (4·8-7·6) for the no treatment group. Bevacizumab alone was non-inferior to standard fluoropyrimidine plus bevacizumab (hazard ratio [HR] 1·08 [95% CI 0·85-1·37]; p=0·53; upper limit of the one-sided 99·8% CI 1·42), whereas no treatment was not (HR 1·26 [0·99-1·60]; p=0·056; upper limit of the one-sided 99·8% CI 1·65). The protocol-defined re-induction after first progression was rarely done (30 [19%] patients in the fluoropyrimidine plus bevacizumab group, 67 [43%] in the bevacizumab monotherapy group, and 73 [46%] in the no treatment group. The most common grade 3 adverse event was sensory neuropathy (21 [13%] of 158 patients in the fluoropyrimidine plus bevacizumab group, 22 [14%] of 156 patients in the bevacizumab alone group, and 12 [8%] of 158 patients in the no treatment group). INTERPRETATION: Although non-inferiority for bevacizumab alone was demonstrated for the primary endpoint, maintenance treatment with a fluoropyrimidine plus bevacizumab may be the preferable option for patients following an induction treatment with a fluoropyrimidine, oxaliplatin, and bevacizumab, as it allows the planned discontinuation of the initial combination without compromising time with controlled disease. Only a few patients were exposed to re-induction treatment, thus deeming the primary endpoint time to failure of strategy non-informative and clinically irrelevant. Progression-free survival and overall survival should be considered primary endpoints in future trials exploring maintenance strategies.