Abstract Number: 345

A randomised, placebo-controlled, phase II trial of adjuvant Avelumab in patients with stage I-III Merkel cell carcinoma (I-MAT Trial)

W. Xu1, M. Poulsen2, V. Atkinson3, G. Fogarty4, M. Veness5, B. Smithers , D. Gyorki , V. Mar , J. Howle , A. Guminski , N. Williams9, E. Paton9

Meeting: 2021 Dermcoll

Session Information

Date: -

Session Title: Poster Presentations

Session Time: -

Background: The rarity of Merkel Cell Carcinoma (MCC) has meant a paucity of prospective trials from which to establish ‘best practice’, as a result significant heterogene- ity exists between centres in the optimal loco-regional management of early stage MCC. The Australian MCC population has a unique biology, predominantly UV-driven with a high tumour mutational burden (TMB), compared with the northern hemisphere’s MCC population, majority viral-driven with low TMB. Anti-PD1/PDL1 based immunotherapy has recently become standard of care for advanced/metastatic MCC, but currently no data exists on the efficacy of immunotherapy as adjuvant treatment for definitively treated stage I-III MCC.

Methods: A phase II, prospective, randomised, placebo- controlled, multi-institutional trial for patients with stage I- III MCC. Treatment will be avelumab vs placebo for
6 months duration. The primary aim of the trial is to develop an effective, well-tolerated adjuvant immunother- apy regimen. The primary endpoint is recurrence-free sur- vival (RFS) assessed at 24 months. Secondary endpoints include overall survival (OS), rates of loco-regional con- trol, distant metastasis free survival (DMFS), rates of toxic- ity and quality of life (QOL).

Results: Recruitment of 132 participants from 15 multina- tional sites over three years commencing the first quarter of 2020, with last patient last visit to be October 2024.

Conclusion: Due to the 2018 Medical Research Futures Fund (Rare Cancers, Rare Diseases, Unmet Needs) grant success and support by Merck Serono, the trial is on track to open in Australia, with international sites to follow. Extensive consultation with all disciplines and interna- tional collaborators will ensure the success of the trial.