Biotech Firm Secures $57.5M Series B with Cytokinetics Support

Imbria Pharmaceuticals, a biotech company incubated by RA Capital, has successfully raised $57.5 million in a Series B funding round. This investment will enable the company to initiate a mid-stage trial of its cardiovascular drug, ninerafaxstat, during the current quarter, with an anticipated outcome by late 2026. With this recent infusion of capital, Imbria Pharmaceuticals has accumulated approximately $150 million in total equity financing. The Boston-based startup, which employs a team of eight, had not previously disclosed its funding achievements. The company's financial supporters include RA Capital, SV Health Investors, Deep Track Capital, AN Ventures, and Catalio Capital Management.

The funds are allocated to demonstrate the efficacy of ninerafaxstat, an oral medication, in treating individuals with non-obstructive hypertrophic cardiomyopathy (HCM) as part of a Phase 2b study. CEO Alvin Shih, who joined Imbria as a board member last year and is now leading the company, has stated that this financial backing provides operational runway until the second half of 2027. Anne Prener, Imbria's president and CEO from 2020 until September, was previously a partner at SV Health.

Shih has been navigating the challenges of securing investment in a tough economic climate. He acknowledged that while the process was difficult, it was not as insurmountable as his previous fundraising efforts for Catamaran Bio, a cell therapy biotech focused on CAR-NK cell therapy, which ceased operations last year.

Imbria is also gaining from the expertise of Cytokinetics, which contributed to the Series B funding. Shih emphasized that Cytokinetics’ involvement is a validation of Imbria's approach. Although Cytokinetics' drug aficamten is in the late stages of development for similar cardiovascular conditions, the company does not have any operational influence over ninerafaxstat.

Looking ahead, Imbria plans to extend the testing of ninerafaxstat, a twice-daily administration, to other cardiovascular conditions such as heart failure with preserved ejection fraction (HFpEF), potentially in collaboration with a partner. The drug has already completed a Phase 2a trial for HFpEF and met its primary endpoint, as reported at the recent American College of Cardiology conference.

Shih highlighted the growing prevalence of HFpEF, describing it as an "epidemic" and noting that despite existing treatments like GLP-1s, there remains a need for additional therapeutic options. Ninerafaxstat is a partial fatty acid oxidation (pFOX) inhibitor, designed to shift the heart's energy demand from fatty acids to glucose, potentially enhancing metabolic performance and improving cardiac function.

Shih reported that the experimental oral drug has shown promising results in improving "cardiac energetics," functional outcomes, and quality of life measures, particularly on the Kansas City Cardiomyopathy Questionnaire, a tool used by heart failure patients. He noted that these improvements could serve as pivotal endpoints for approval in both HCM and HFpEF.

The concept for ninerafaxstat originated from an older drug, trimetazidine, which has been used in Europe for treating angina but lacks FDA approval in the U.S. RA Capital sought to optimize this molecule, resulting in the creation of a new compound that includes trimetazidine among its metabolites, along with other active components. Shih remarked that this approach maximizes the mechanism's potential, particularly within the cardiac mitochondria.