1146P - Updated results from POD1UM-201: A phase II study of retifanlimab in patients with advanced or metastatic Merkel cell carcinoma (MCC)

Background

Retifanlimab, a programmed death receptor-1 (PD-1)–blocking antibody, was recently approved in the United States for treatment of adult patients (pts) with metastatic or recurrent locally advanced MCC based on results from the open-label, single-arm POD1UM-201 study (NCT03599713). In the primary analysis including 65 chemotherapy-naive pts, responses were observed in 52% (95% CI: 40–65) of pts with 62% of responses exceeding 12 months by landmark analysis (ZYNYZ^TM prescribing information). Safety was as expected for the PD-(L)1 inhibitor class. We present updated results on the full cohort of 101 pts.

Methods

Eligible pts were ≥18 years of age, had metastatic or recurrent unresectable loco-regional MCC, Eastern Cooperative Oncology Group (ECOG) performance status ≤1, measurable disease per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1, and had not received prior MCC systemic treatment. Retifanlimab 500 mg was administered intravenously every 4 weeks (Q4W) for up to 2 years without premedication prophylaxis. The primary endpoint was overall response rate assessed by independent central review per RECIST v1.1. Secondary endpoints included duration of response, disease control rate, progression-free survival, overall survival, safety, and pharmacokinetics.

Results

The study enrolled 101 pts with chemotherapy-naive advanced/metastatic MCC, with the last pt initiating treatment on 24 June 2021. Pt and disease characteristics were representative of the typical MCC epidemiology. The median age was 71 (range, 38–90) years, 68 (67%) pts were male and predominantly white, 74 (73%) had an ECOG of 0, and one pt was HIV positive. A total of 91 (90%) pts had Stage IV disease, 69 (68%) had prior surgery, and 37 (37%) had prior radiotherapy. In evaluable tumour samples, Merkel cell polyomavirus was detectable in 73/96 (76%) and 83/95 (87%) had PD-L1 expression ≥1%. Efficacy and safety results for the full study population will be presented.

Conclusions

Retifanlimab has shown notable clinical activity with an acceptable safety in advanced/metastatic chemotherapy-naive MCC, and is a promising new treatment option for eligible pts.

Clinical trial identification

NCT03599713, EudraCT 2018-001627-39.

Editorial acknowledgement

Envision Pharma Group (Philadelphia, PA), funded by Incyte Corporation (Wilmington, DE).

Legal entity responsible for the study

Incyte Corporation (Wilmington, DE).

Funding

Incyte Corporation, Wilmington, DE.

Disclosure

G. Grignani: Financial Interests, Institutional, Other, Honoraria: Bayer, Eisai, Eli Lilly and Company, Merck, Novartis, Pfizer, PharmaMar; Financial Interests, Institutional, Advisory Role: Bayer, Eisai, Eli Lilly and Company, Novartis, Pfizer, PharmaMar; Financial Interests, Institutional, Research Grant: Bayer, Novartis, PharmaMar. P. Rutkowski: Financial Interests, Institutional, Advisory Board, Honoraria: AstraZeneca Blueprint Medicines, Bristol Meyers Squibb, Merck Serono, MSD, Novartis, Philogen, Pierre Fabre, Sanofi; Financial Interests, Institutional, Other, Institutional support: Pfizer. C. Lebbe: Financial Interests, Personal, Advisory Board: Bristol Myers Squibb, MSD, Novartis, Amgen, Roche, Merck Serono, Sanofi, Pierre Fabre; Financial Interests, Personal, Funding: Roche, Bristol Myers Squibb; Non-Financial Interests, Advisory Role: Bristol Myers Squibb, MSD, Novartis, Amgen, Roche, Merck Serono, Sanofi, Pierre Fabre; Other, Honoraria, Speaker's Bureau, Research funding: Roche; Other, Honoraria, Speaker's bureau, Travel, Accommodation, Expenses, Research funding, Board: Bristol Myers Squibb; Other, Honoraria, Speaker's bureau, Travel, Accommodations, Expenses, Board: Novartis, MSD; Other, Honoraria, Speaker's bureau: Amgen; Other, Honoraria, Travel, Accommodations, Expenses, Board: Pierre Fabre; Other, Honoraria: Pfizer; Other, Honoraria: Incyte; Other, Travel, accommodations, Expenses, Board: Sanofi; Other, Board: Avantis Medical Systems, Jazz Pharmaceuticals; Other, Participation on a Data Safety Monitoring Board or Advisory Board: InflaRx. M. Guida: Financial Interests, Institutional, Advisory Role: Bristol Myers Squibb, MSD, Novartis, Pierre Fabre. C. Gaudy Marqueste: Financial Interests, Institutional, Advisory Board, Honoraria: Bristol Myers Squibb, MSD, Pierre Fabre; Financial Interests, Institutional, Other, Participated in clinical trials and Travel grants: Bristol Myers Squibb, MSD, Pierre Fabre; Financial Interests, Institutional, Other, Participated in clinical trials: GSK, Huyabioscience, Incyte, Merck Serono, Novartis, Regeneron, Replimune, Kartos. F.G.M. De Braud: Financial Interests, Institutional, Advisory Role: Roche, EMD Serono, NMS Nerviano Medical Science, Sanofi, MSD, Incyte, Bristol Myers Squibb, Menarini, AstraZeneca, Pierre Fabre, Mattiolo 1885 , MCCann Health, Taiho; Financial Interests, Institutional, Speaker’s Bureau: Bristol Myers Squibb, Healthcare Research & Pharmacoepidemiology, Merck, MSD, Pfizer, Servier, Sanofi, Roche, Amgen, Incyte, Dephaforum, Seagen, Nadirex, Ambrosetti, Itanet; Financial Interests, Funding, Research: Novartis, Hoffmann LaRoche Ltd., Bristol Myers Squibb, Ignyta Operating INC, Kymab, Pfizer, Tesaro, MSD, MedImmune LCC, Exelixis Inc., Loxo Oncology Incorporated, Daiichi Sankyo Dev. Limited, Basilea Pharmaceutica International AG, Janssen Cilag International NV, Merck KGaA, IQVIA. F. Spagnolo: Financial Interests, Institutional, Advisory Board: Bristol Myers Squibb, Merck, MSD, Novartis, Pierre Fabre, Philogen, Sanofi, Sun Pharma. M. Burgess: Financial Interests, Institutional, Funding, Research: Merck; Financial Interests, Institutional, Advisory Board: EMD Serono, Immune Design, SpringWorks Therapeutics. H. Montaudie: Financial Interests, Institutional, Other, Honoraria: Bristol Myers Squibb, Merck Serono, MSD, Novartis, Pierre Fabre; Financial Interests, Institutional, Other, Institutional support: Bristol Myers Squibb, Leo Pharma; Financial Interests, Institutional, Other, Participated in clinical trials: Bristol Myers Squibb, Checkpoint Therapeutics, Huyabioscience, Incyte, Merck Serono, MSD, Nektar Pharmaceuticals, Novartis, Pierre Fabre, Regeneron, Replimune; Financial Interests, Institutional, Other, Travel grant: Bristol Myers Squibb, Pierre Fabre, Novartis. R. Depenni: Financial Interests, Institutional, Advisory Board: Bristol Myers Squibb, MSD, Novartis, Pierre Fabre, Sanofi. F. Spada: Financial Interests, Institutional, Other, Honoraria for lectures and/or advisory boards and/or manuscript writing: Advanced Accelerator Application, Ipsen, Merck/MSD, Novartis, Pfizer; Financial Interests, Institutional, Invited Speaker, Institutional support: GETNE, Hutchmed, Incyte Corporation. J. Pulini, M. Cornfeld, C. Tian: Financial Interests, Institutional, Full or part-time Employment: Incyte; Financial Interests, Institutional, Stocks/Shares: Incyte. S. Bhatia: Financial Interests, Institutional, Advisory Board: Bristol Myers Squibb, Castle Biosciences, EMD Serono, Exicure, Genentech, Incyte, Sanofi-Genzyme; Financial Interests, Institutional, Research Grant: 4SC, Amphivena Therapeutics, Bristol Myers Squibb, Checkmate, EMD Serono, Immune Design, Incyte Biosciences, Merck, NantKwest, Nektar, Novartis, OncoSec, Regeneron, Xencor; Financial Interests, Institutional, Stocks/Shares: Moderna.