Phanes Therapeutics announced that the first patient has been dosed in a clinical study evaluating mavrostobart (PT199) in combination with chemotherapy, marking a significant milestone for the clinical-stage biotech company's oncology pipeline. The announcement represents progress in developing what the company describes as a differentiated anti-CD73 monoclonal antibody designed to counter adenosine-mediated immunosuppression in the tumor microenvironment.
Differentiated Mechanism of Action
Mavrostobart distinguishes itself from other anti-CD73 antibodies through its complete inhibition of enzyme activities in both soluble and membrane-bound CD73 forms. According to Phanes Therapeutics, several other anti-CD73 antibodies exhibit incomplete inhibition, a limitation that mavrostobart is designed to address. Additionally, the antibody maintains its inhibitory activity at higher concentrations without experiencing a "hook effect," where efficacy diminishes at elevated doses.
The anti-CD73 mechanism targets the adenosine-mediated immunosuppressive tumor microenvironment, with the goal of increasing antitumor immune activation and potentially offering a new treatment option for cancer patients.
MORNINGSTAR Study Design
The multi-center Phase I/II clinical trial, designated as the MORNINGSTAR study (NCT05431270), is evaluating multiple parameters of mavrostobart treatment. The study is assessing safety, tolerability, pharmacokinetics and preliminary efficacy of mavrostobart both as a monotherapy and in combination with PD-1 inhibitors or chemotherapy.
A separate Phase I clinical trial of mavrostobart is also ongoing in China under the designation CTR20242381, expanding the geographic scope of the drug's clinical evaluation.
Broader Pipeline Development
Phanes Therapeutics is currently conducting three Phase I/II clinical trials as part of its oncology-focused development program. Beyond the MORNINGSTAR study with mavrostobart, the company is advancing the TWINPEAK study with spevatamig (PT886) and the SKYBRIDGE study with peluntamig (PT217). Both spevatamig and peluntamig are described as first-in-class bispecific antibodies that have received orphan drug designations and Fast Track designations from the FDA.
Proprietary Technology Platforms
The company has developed its pipeline using three proprietary technology platforms: PACbody, SPECpair and ATACCbody. These platforms are designed to develop novel biologics that address high unmet medical needs in cancer treatment, supporting the company's focus on innovative drug discovery and development in oncology.
