Overview

This is a Phase 1a/1b, dose-escalation/expansion, consecutive-cohort, open-label study to evaluate the safety, tolerability, PK, PD, and preliminary evidence of antitumor activity of PLN-101095 in combination with pembrolizumab (the study treatment regimen) in adult participants with advanced or metastatic solid tumors for which pembrolizumab is indicated but have documented disease progression (refractory [primary resistance]) or relapsed [secondary resistance]) after at least 3 months from the start of treatment with pembrolizumab.

The study will consist of 2 main parts:

• Part 1: Consecutive dose-escalation cohorts using a Bayesian optimal interval (BOIN) dose escalation design
• Part 2: Dose-expansion cohorts using Simon's 2-stage design

Eligibility

Inclusion Criteria:

1. Has histologically or cytologically confirmed advanced solid tumor
2. Has an advanced or metastatic solid tumor (for which pembrolizumab is indicated) and have evidence of disease progression after treatment with pembrolizumab.
3. At least 1 measurable lesion, as defined by RECIST v1.1
4. Estimated survival of ≥3 months
5. No effective therapeutic options available (eg, has received standard of care or is intolerant of, refuses, or is not eligible for standard of care antineoplastic therapy)

Exclusion Criteria:

1. Any immune-related medical conditions that would put participants at greater risk when receiving pembrolizumab
2. Previous treatment with pembrolizumab <21 days prior to the first dose of combination therapy of pembrolizumab and PLN-101095
3. Received an immunotherapy other than pembrolizumab in the last 4 weeks prior to the first dose of PLN-101095
4. Received radiotherapy (RT) within 1 week for palliative bone-directed therapy and 4 weeks for all other types, prior to the first dose of PLN-101095
5. Received chemotherapy or other targeted therapies within 2 weeks prior to the first dose of PLN-101095
6. Received a cell therapy within the last 12 months prior to the first dose of PLN-101095
7. Known active central nervous system (CNS) metastases (brain and/or leptomeningeal metastases)
8. Pregnant or lactating female participant