On January 8, 2026 Osel Inc., a clinical-stage biopharma company pioneering live biotherapeutic products (LBPs), reported a clinical trial agreement with SWOG Cancer Research Network for a pivotal Phase 3 clinical trial of its lead oncology candidate, MO-03, in combination with standard immuno-oncology (IO) regimens for advanced and metastatic renal cell carcinoma (mRCC). This marks the first-ever pivotal trial of a microbiome-based oral therapy in oncology.
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The BIOFRONT trial will build on promising results from two prior clinical studies led by Dr. Sumanta Kumar Pal, MD, FASCO at City of Hope. In those studies, prior formulations of the product were added to nivolumab and ipilimumab or to cabozantinib and nivolumab and showed statistically significant improvements in response rates and progression free survival, without added toxicity.1,2 A recent dose-escalation study confirmed favorable safety across higher dose levels, with no increase in immune-related adverse events, leading to a new high-potency capsule formulation, MO-03, specific for oncology.
"The study represents a major advance for patients with advanced RCC," said Dr. Pal. "While other combination approaches in the front-line setting add significant toxicity, MO-03 could possibly augment the efficacy of immunotherapy-based regimens without compromising quality of life."
The Phase 3 randomized, double-blind study will enroll approximately 700 patients across up to 150 SWOG sites in the United States, comparing MO-03 plus approved IO therapy versus placebo plus IO. The trial is supported by the National Cancer Institute (NCI), part of the National Institutes of Health. Trial initiation is slated for Q1 2026.
MO-03 is a high-potency capsule formulation of Clostridium butyricum Miyairi 588 (CBM588), developed specifically for oncology by Osel and Japan’s Miyarisan Pharmaceutical Co., which will supply the GMP product. Osel holds the Investigational New Drug applications (INDs) for CBM588 and MO-03 in the United States and has exclusive marketing rights to CBM588 and MO-03 pharmaceutical products in the United States, Canada, and Europe.
"We appreciate the investment that SWOG/NCI is making in this pivotal trial, which will position MO-03 as a first-in-class LBP in oncology," said Peter P. Lee, MD, Chairman of Osel. "We are actively working with Miyarisan to engage partners who are interested in commercializing MO-03, pending positive Phase 3 results. Recent market research among US oncologists and payers shows strong interest in MO-03 and a high likelihood of coverage in the mRCC setting."
The BIOFRONT trial, formally titled "S2419, Phase III Double Blinded Trial of Immune-Based Therapy with a Live Biotherapeutic CBM588 or Placebo for Frontline Therapy of Advanced Clear Cell Renal Cell Carcinoma," is led by Principal Investigator (PI) Pedro C. Barata, MD, MSc, at University Hospitals Seidman Cancer Center. Co-PIs are Ulka Vaishampayan, MD, at University of Michigan Rogel Cancer Center, and Sumanta K. Pal, MD, at City of Hope.
Osel holds the exclusive worldwide intellectual property rights for the use of Clostridium butyricum in oncology in combination with immune checkpoint inhibitors (ICIs) including the PD-1, PD-L1 and CTLA-4 inhibitors nivolumab, ipilimumab, pembrolizumab, cemiplimab, durvalumab, daclizumab, avelumab, or atezolizumab. The allowed claims specifically cover Clostridium butyricum as the sole live biotherapeutic product in combination regimens with ICIs and other anti-cancer agents. The intellectual property includes not only renal cell cancer but also extends to other major malignancies and microsatellite-instability high (MSI-H) cancers, including non-small cell lung cancer, melanoma, sarcoma, lymphoma, breast cancer, bladder cancer, cervical cancer, colon cancer, head and neck cancer, liver cancer, stomach cancer, or rectal cancer, supporting the broad clinical potential of MO-03.
(Press release, Osel, JAN 8, 2026, View Source [SID1234661879])