Safety and Efficacy of XmAb18087 ± Pembrolizumab in Advanced Merkel Cell Carcinoma or Extensive-stage Small Cell Lung Cancer

A Phase 1b/2 Multiple-Dose Study to Evaluate the Safety and Efficacy of XmAb18087 ± Pembrolizumab in Subjects With Advanced Merkel Cell Carcinoma or Extensive-stage Small Cell Lung Cancer (DUET-1-02) Protocol

This is a Phase 1b/2, multiple-dose study designed to describe safety and efficacy, and to assess PK and immunogenicity of XmAb18087 monotherapy and in combination with pembrolizumab in participants with metastatic Merkel cell (MCC) or locoregional MCC that has recurred after locoregional therapy with surgery and/or radiation therapy, and mAb18087 monotherapy in participants with extensive-stage small cell lung cancer (SCLC) that has progressed after standard therapies.

This study was terminated by the sponsor. No participants enrolled in Part B.

Inclusion Criteria:

• Able to provide written informed consent
• Adult participants ≥ 18 years
• Disease measurable by RECIST 1.1 criteria using either computed tomography (CT) or magnetic resonance imaging (MRI) scan
• Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1
• All participants must have adequate archival tumor sample (slides or archival formalin-fixed paraffin-embedded [FFPE] block[s] containing tumor that has not been previously irradiated
• Female participants of childbearing potential must agree to use a highly effective method of birth control during and for 4 weeks after completion of study. success), or sexual abstinence
• Fertile male participants must be willing to practice a highly effective method of birth control for the duration of the study and continuing for 4 weeks after the last dose of XmAb18087 or pembrolizumab (when applicable
• Able and willing to complete the entire study according to the study schedule

Additional Inclusion Criteria for Part A and Part B Cohorts:

• Histologically or cytologically confirmed metastatic MCC or locoregional MCC that has recurred following standard locoregional therapy with surgery and/or radiation therapy.

Additional Inclusion Criteria for Part A Cohorts:

• Participants must have progressed on or been ineligible for treatment with anti-PD1 or anti-PDL1 therapy.

Additional Inclusion Criteria for Part B Cohorts:

• Participants must be eligible to receive pembrolizumab as standard of care.

Additional Inclusion Criteria for Part C Cohorts:

• Histologically or cytologically confirmed extensive-stage SCLC that has progressed following standard therapies

Exclusion Criteria:

Additional Exclusion Criteria for Part B Cohorts: XmAb18087 in Combination with Pembrolizumab

• Prior treatment with therapeutics directed at anti-programmed cell death 1 (anti-PD1) or anti-programmed cell death ligand 1 (anti-PDL1)
• Have severe hypersensitivity (≥ Grade 3) to pembrolizumab and/or any of its excipients