Placebo-Controlled Trial of IFx-Hu2.0 Followed By Pembrolizumab In Checkpoint Inhibitor Naïve Participants With Advanced Or Metastatic Merkel Cell Carcinoma

Inclusion criteria

• At least 18 years of age.
• Life expectancy equal to or greater than six months.
• Eastern Cooperative Oncology Group (ECOG) Performance Status < 2.
• Must be recurrent and/or unresectable Stage III or Stage IV American Joint Committee on Cancer (AJCC) (8th edition) and have histologically confirmed Merkel cell carcinoma

• Must have at least one injectable lesion equal to or greater than 3 mm.
• Must have measurable disease as defined by RECIST v1.1.
• Participants should be CPI naïve i.e., no prior therapy with CPI including but not limited to Pembrolizumab, avelumab, ipilimumab, nivolumab.
• Tumor tissue from an archival core biopsy or resected site of disease must be provided for biomarker analyses. If archival tissue is not available, then a new biopsy should be performed.
• Adequate hematological, hepatic, and renal function according to laboratory ranges and medical criteria defined within the study protocol.

Exclusion criteria

• Uncontrolled intercurrent illness including, but not limited to, ongoing or active infection, symptomatic congestive heart failure, unstable angina pectoris, cardiac arrhythmia, or psychiatric illness/social situations that would limit compliance with protocol requirements.
• Participants with known active brain metastases with the exception of treated brain metastases that have imaging proving stability at least 4 weeks prior to the start of study treatment, no new metastases, and not requiring steroids.
• Participants with recurrent resectable MCC
• Participants with prior systemic chemotherapy
• Pregnant or breastfeeding females and females desiring to become pregnant or breastfeed within the timeframe of this study.
• Active, known, or suspected autoimmune disease. Potential Participants with type I diabetes mellitus, residual hypothyroidism due to autoimmune thyroiditis only requiring hormone replacement, skin disorders (such as vitiligo, psoriasis, or alopecia) not requiring systemic treatment are permitted to enroll. Low-grade autoimmune toxicity is NOT an exclusion under this criterion.
• A condition requiring systemic treatment with either corticosteroids (> 10 mg daily prednisone equivalent) or other immunosuppressive medications within 14 days of randomization. Inhaled or topical steroids are permitted in the absence of active autoimmune disease.