Additionally, evidence suggests CBM588 can complement IO regimens or other therapies to improve outcomes without adding toxicity, reinforcing MO-03’s potential.

The formal trial name is S2419, a Phase III double-blinded study evaluating immune-based therapy with CBM588 versus placebo for frontline treatment of advanced clear cell renal cell carcinoma, with enrollment expected to begin in 2026.

MO-03 is the high-potency CBM588 capsule developed with Miyarisan, and Osel holds US INDs and exclusive marketing rights in the U.S., Canada, and Europe, with GMP product supplied by Miyarisan.

The BIOFRONT trial is led by PI Pedro C. Barata at University Hospitals Seidman Cancer Center, with co-PIs Ulka Vaishampayan and Sumanta K. Pal, and is supported by NCI/NIH funding.

Context notes that MO-03 builds on prior national and international research indicating enhanced efficacy of IO regimens with microbial supplementation, strengthening the trial’s scientific rationale.

The trial is built on prior research showing MO-03 can enhance immune-based regimens, with prior work indicating higher response rates and longer progression-free survival when CBM588 is added to IO therapies, without added toxicity.

Osel has partnered with Miyarisan and other collaborators to advance MO-03 development, with early stages focusing on regulatory and market considerations and signaling increased interest from the oncology community.

Osel Inc. is launching BIOFRONT, a pivotal Phase 3 trial of MO-03, a high-potency live biotherapeutic, in combination with standard immunotherapy for advanced and metastatic renal cell carcinoma, marking the first pivotal study of a microbiome-based oral therapy in oncology.

The program has backing from national research and health institutions, including federal support for setting standards in anti-cancer care and broader immune therapy research.

Earlier studies by Dr. Pal demonstrated safety and activity of MO-03 when combined with various IO regimens, and a dose-escalation study confirmed safety at higher doses to enable the MO-03 formulation.

The Phase 3 trial plans to enroll about 700 patients across up to 150 SWOG sites in the U.S., comparing MO-03 plus IO therapy to placebo plus IO, with initiation targeted for early 2026.

Osel holds exclusive worldwide IP rights for using Clostridium butyricum with immune checkpoint inhibitors in oncology, suggesting MO-03 could have broad applicability beyond RCC.