Safety and Efficacy of Induction and Maintenance Avelumab Plus R-CHOP in Patients with Diffuse Large B-Cell Lymphoma (DLBCL): Analysis of the Phase II Avr-CHOP Study

Background: Novel strategies are needed to improve upon the 60% cure rate of upfront R-CHOP in advanced DLBCL. Single-agent immune checkpoint inhibition (ICI) has limited efficacy in heavily pre-treated DLBCL (response rate Avelumab (Av) is an anti-PDL1 monoclonal antibody with antibody dependent cell cytotoxicity (ADCC) activity which acts synergistically with rituximab (R) in vitro. We report the results of a phase II single arm study assessing safety of 1st line sequential AvR induction, R-CHOP & Av maintenance for DLBCL. Methods: Patients aged ≥18 years, ECOG 0-2 with untreated stage II-IV DLBCL and no active autoimmune disease were treated with AvR induction x2 cycles q2-weekly (Av 10mg/kg IV + R 375mg/m2 IV), followed by R-CHOP21 x 6 cycles then Av 10mg/kg x 6 cycles q2-weekly if in complete metabolic response (CMR) post R-CHOP. The primary endpoint was the rate of grade 3/4 immune-related adverse events (irAE). Secondary endpoints included overall response rate (ORR), failure free survival (FFS), overall survival (OS) and overall toxicity. Response was determined centrally by PET-CT (Lugano 2014 criteria). CMR rates by PET-CT post AvR induction and post C2 R-CHOP were exploratory endpoints. Genomic analysis was performed including next generation sequencing (NGS) based sequence variant detection, copy number analysis and structural variant detection. Results: 28 pts were enrolled from Dec 2017 to Oct 2019. Key baseline characteristics included median age 54 yrs (range 20-79); stage III/IV disease 68%; elevated LDH 61%; IPI ≥2 25%. Histology included 21 DLBCL NOS (75%; 14 GCB, 7 non-GCB by Hans algorithm), 6 primary mediastinal B-cell lymphoma (PMBCL; 21%) and 1 EBV positive DLBCL (4%). The study met its pre-specified primary endpoint of G3/4 irAE ORR post R-CHOP was 89% (all CR) (Figure 1). The ORR to 2 cycles of induction AvR was 60%, including 6 CMR (21%) across all diagnostic/histologic subgroups (n=1 PMBCL, n=2 non-GCB DLBCL, n=3 GCB DLBCL; Figures 1 and 2). Six pts (21%) progressed during AvR induction (with 1 pt completing only 1 x AvR cycle); all subsequently responded to R-CHOP. With a median follow-up of 16 months, 1-year FFS was 76% and OS 89%. Treatment was discontinued early in 5 pts; 2 during R-CHOP due to progressive disease and 3 during Av maintenance (n=1 immune hepatitis; n=1 pulmonary embolism initially reported as pneumonitis; n=1 progressive disease). Alterations in the CD274/PDCDLG2 locus were identified by NGS in 3 of 27 evaluable pts (n=2 PMBCL, n=1 EBV+ DLBCL). Full genomic analysis to identify factors associated with response will be presented. Conclusion: Sequential AvR induction, R-CHOP and Av maintenance in pts with newly diagnosed DLBCL is feasible with a manageable toxicity profile and a high CR rate. Responses to AvR alone were higher than expected based on the relapsed/refractory population and may suggest superior efficacy of ICI in the frontline setting. These results support ongoing sequential studies of immune priming with PD1/PDL1 inhibition prior to R-CHOP in DLBCL. Acknowledgements: Merck KgA for avelumab plus funding. Tour de Cure Scott Canning Early Career Grant (E Hawkes) and Wilson Centre for Lymphoma Genomics for biomarker testing. Download : Download high-res image (168KB) Download : Download full-size image Disclosures Hawkes: Astra Zeneca: Membership on an entity’s Board of Directors or advisory committees, Research Funding; Gilead: Membership on an entity’s Board of Directors or advisory committees; Roche: Membership on an entity’s Board of Directors or advisory committees, Other: Travel, Research Funding, Speakers Bureau; BMS celgene: Membership on an entity’s Board of Directors or advisory committees, Research Funding, Speakers Bureau; Janssen-Cilag: Membership on an entity’s Board of Directors or advisory committees, Other: Travel, Speakers Bureau; Merck Sharpe D takeda: Speakers Bureau; Merck KgA: Research Funding. Chong: Merck Serono: Research Funding; Bristol-Myers Squibb: Research Funding; Hutchison Medipharma: Research Funding; Bayer: Research Funding; Pharmacyclics LLC, an AbbVie Company: Research Funding; Servier: Research Funding; Isofol: Research Funding. Blombery: Novartis: Consultancy; Janssen: Honoraria; Amgen: Consultancy; Invivoscribe: Honoraria. Barraclough: Roche: Other: Conference sponsorship. Keane: Celgene: Honoraria, Other: Travel; BMS: Research Funding; Roche: Honoraria, Other: Travel, Speakers Bureau; MSD Oncology: Honoraria, Other: Travel; Gilead: Honoraria, Other: Travel, Speakers Bureau. Fong: Pfizer: Honoraria; Astellas: Honoraria; Amgen: Honoraria, Research Funding, Speakers Bureau; Novartis: Honoraria; AbbVie: Honoraria. Manos: Bristol-Myers Squibb: Other: Conference sponsorship. OffLabel Disclosure: Avelumab is an anti-PDL1 monoclonal antibody. Inhibition of the PD1/PDL1 pathway stimulates anti-tumour immunity.