Avelumab in patients with previously treated metastatic Merkel cell carcinoma: long-term data and biomarker analyses from the single-arm phase 2 JAVELIN Merkel 200 trial

J Immunother Cancer. 2020 May;8(1):e000674. doi: 10.1136/jitc-2020-000674.

Abstract

Background: Merkel cell carcinoma (MCC) is a rare, aggressive skin cancer associated with a high risk of metastasis. In 2017, avelumab (anti-programmed death-ligand 1 (PD-L1)) became the first approved treatment for patients with metastatic MCC (mMCC), based on the occurrence of durable responses in a subset of patients. Here, we report long-term efficacy and safety data and exploratory biomarker analyses in patients with mMCC treated with avelumab.

Methods: In a cohort of this single-arm, phase 2 trial (JAVELIN Merkel 200), patients with mMCC and disease progression after prior chemotherapy received avelumab 10 mg/kg intravenously every 2 weeks. The primary endpoint was confirmed objective response rate (ORR) by independent review per Response Evaluation Criteria in Solid Tumors V.1.1. Other assessments included duration of response, progression-free survival, overall survival (OS), safety and biomarker analyses.

Results: As of 14 September 2018, 88 patients had been followed up for a median of 40.8 months (range 36.4-49.7 months). The ORR was 33.0% (95% CI 23.3% to 43.8%), including a complete response in 11.4% (10 patients), and the median duration of response was 40.5 months (95% CI 18.0 months to not estimable). As of 2 May 2019 (≥44 months of follow-up), the median OS was 12.6 months (95% CI 7.5 to 17.1 months) and the 42-month OS rate was 31% (95% CI 22% to 41%). Of long-term survivors (OS >36 months) evaluable for PD-L1 expression status (n=22), 81.8% had PD-L1+ tumors. In exploratory biomarker analyses, high tumor mutational burden (≥2 non-synonymous somatic variants per megabase) and high major histocompatibility complex class I expression (30% of tumors with highest expression) were associated with trends for improved ORR and OS. In long-term safety assessments (≥36 months of follow-up), no new or unexpected adverse events were reported, and no treatment-related deaths occurred.

Conclusions: Avelumab showed continued durable responses and meaningful long-term survival outcomes in patients with mMCC, reinforcing avelumab as a standard-of-care treatment option for this disease.

Trial registration number: NCT02155647.

Keywords: biomarkers, tumor; clinical trials, phase II as topic; immunotherapy; skin neoplasms.

Publication types

  • Clinical Trial, Phase II
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Antibodies, Monoclonal, Humanized / administration & dosage*
  • Antibodies, Monoclonal, Humanized / adverse effects
  • B7-H1 Antigen / antagonists & inhibitors
  • Biomarkers, Tumor / analysis*
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / metabolism
  • Carcinoma, Merkel Cell / drug therapy*
  • Carcinoma, Merkel Cell / genetics
  • Carcinoma, Merkel Cell / immunology
  • Carcinoma, Merkel Cell / mortality
  • Disease Progression
  • Female
  • Follow-Up Studies
  • Histocompatibility Antigens Class I / analysis
  • Histocompatibility Antigens Class I / metabolism
  • Humans
  • Immune Checkpoint Inhibitors / administration & dosage*
  • Immune Checkpoint Inhibitors / adverse effects
  • Male
  • Middle Aged
  • Mutation
  • Progression-Free Survival
  • Response Evaluation Criteria in Solid Tumors
  • Skin / immunology
  • Skin / pathology
  • Skin Neoplasms / drug therapy*
  • Skin Neoplasms / genetics
  • Skin Neoplasms / immunology
  • Skin Neoplasms / mortality
  • Young Adult

Substances

  • Antibodies, Monoclonal, Humanized
  • B7-H1 Antigen
  • Biomarkers, Tumor
  • CD274 protein, human
  • Histocompatibility Antigens Class I
  • Immune Checkpoint Inhibitors
  • avelumab

Associated data

  • ClinicalTrials.gov/NCT02155647