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IntroductionIn 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.MethodsThe 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 DiscussionIn 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 RegistrationClinicalTrials.gov, identifier (NCT03174405).

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)., Competing Interests: AS received institutional research grants from Merck, BMS, Roche, Sanofi, Servier and honoraria for lectures and advisory board meetings by Merck, Roche, Amgen, Lilly, Sanofi- Aventis, Servier, Bayer, BMS, MSD and Sirtex. S-EA-B has an advisory role with Merck, Roche, Celgene, Lilly, Nordic Pharma, Bristol- Myers Squibb, Astellas and MSD Sharp & Dohme; is a speaker for Roche, Celgene, Lilly, Nordic Pharma, AIO gGmbH, MCI, promedicis, Forum für Medizinische Fortbildung and Taiho pharma; he is CEO/founder of IKF Klinische Krebsforschung GmbH at Northwest Hospital; and has received research grants from Sanofi, Merck, Roche, Celgene, Vifor, Medac, Hospira, Lilly, Eurozyto, German Cancer Aid (Krebshilfe), German Research Foundation and the Federal Ministry of Education and Research. UP received institutional research grants from Celgene, BMS, Amgen, Lilly, Roche, Sanofi and Servier and honoraria for lectures and advisory board meetings by Roche, Celgene, Amgen, Lilly, Sanofi- Aventis, Servier, Bayer and BMS. AH received honoraria for lectures from Roche. CB received institutional research grants and honoraria for lectures and advisory board meetings from Merck, BMS, Roche, Sanofi, Servier, Bayer, BMS, Astrazeneca, Lilly, Mundipharma, Hexal, MSD and GSO. MBi received institutional research grants from Merck, BMS, Hexal, German Cancer Aid (Krebshilfe), German Research Foundation and the Federal Ministry of Education and Research as well as honoraria for lectures and advisory board meetings by Celgene, Janssen, Gilead, Merck, Roche, Amgen, Sanofi-Aventis and BMS., (Copyright © 2022 Tintelnot, Ristow, Sauer, Simnica, Schultheiß, Scholz, Goekkurt, von Wenserski, Willscher, Paschold, Lorenzen, Riera-Knorrenschild, Depenbusch, Ettrich, Dörfel, Al-Batran, Karthaus, Pelzer, Hinke, Bauer, Massa, Seliger, Wickenhauser, Bokemeyer, Hegewisch-Becker, Binder and Stein.)