Oncotelic Therapeutics, Inc. announced the clearance of the Phase 2 clinical trial protocol for mesothelioma after filing the protocol to the Food and Drug Administration. Oncotelic is initiating a Phase 2 Investigator Initiated Study (IIS) clinical trial in patients with metastatic plural mesothelioma (MPM) in collaboration with Merck who is supplying pembrolizumab for the study. The trial is titled M201: Phase 2 Trial of TGF-ß Inhibition (OT-101) with Anti-PD-1 (pembrolizumab) in Patients with Malignant Pleural Mesothelioma (MPM) Failing to Achieve or Maintain Response to Checkpoint Inhibition.

The trial is expected to enroll up to 63 patients across multiple centers in the U.S., including the center with the Principal Investigator - Melina Marmarelis, MD MSCE, Assistant Professor, Perelman School of Medicine, University of Pennsylvania, Medical Director of the University of Pennsylvania Pleural and Mesothelioma Center. This is a phase 2, open label, non-randomized, single arm Simon's two stage study in subjects with malignant pleural mesothelioma failing to achieve or maintain response to checkpoint inhibition. Before the efficacy assessment portion, the study will first embark a run-in dose-escalation phase to evaluate safety and tolerability of various dose of OT-101 in combination of pembrolizumab, and to determine a recommended Phase 2 dose (RP2D) of 4 days continuous i.v. infusion for every two weeks regimen.

Subjects received the RP2D in the run-in dose-escalation phase will be part of the first stage of the Simon's two-stage design for effectiveness evaluation. A maximum of 63 subjects will be treated. Among them, a maximum of 30 subjects will be treated in the run-in dose-escalation phase to determine the MTD and RP2D.

Thirty-nine subjects are required for the Simon's two-stage assessment of efficacy: 19 subjects in the first stage, and 20 in the second stage. Subjects of the RP2D cohort in the run-in dose-escalation phase will be included in the first stage of the Simon's two-stage assessment. To determine whether the administration of TGF-ß inhibitor (OT-101) in combination with pembrolizumab can provide improved tumor response (ORR) in MPM subjects that fail to achieve or maintain a response with anti-PD-1/PD-L1-based regimens.

Secondary Objectives: to determine whether ORR induced by TGF-ß inhibition combined with PD-1 blockade will result in an improved duration of response (DOR) and 6-month and 12-month Overall Survival (OS) and progression-free survival (PFS) as compared to current data with single agent pembrolizumab.; To evaluate the safety and tolerability of the administration of OT-101, in combination with pembrolizumab in patients with mesothelioma. Exploratory Objective; To determine whether TGF-ß inhibition combined with PD-1 blockade will increase T cell infiltration, clonality in some tumors; and, the increased T cell infiltration, clonality (CD4, CD8 and Tregs) and IFN- ? signatures correlate with the reduced TBRS.

To determine if pretreatment TBRS signature is predictive of improved efficacy per ORR, DOR, and 6-month and 12-month overall survival OS, and progression free survival PFS.