Today Keros Therapeutics announced that it had decided to completely halt any further clinical development of its drug cibotercept (KER-012) for the treatment of patients with pulmonary arterial hypertension (PAH). Where the problem first started for this company was back in December of 2024, when the company had voluntarily decided to halt dosing of 3.0 mg/kg and 4.5 mg/kg of this drug in the phase 2 TROPOS study based on observations of pericardial effusions for these doses. This wouldn’t have been that big of an issue so long as it was able to keep giving patients the low-dose version of this drug. Unfortunately, things got worse, whereby it was stated in January of 2025 that it would halt all further dosing of this study.
The goal of the phase 2 TROPOS study was to assess cibotercept in combination with background therapy for the treatment of patients with PAH. This drug was developed to bind to and inhibit TGF-β signaling. The thought process here was to eliminate this protein’s ability to cause the formation of fibrotic tissue and hypertrophy (muscle cells expanding in size) from taking place. Plus, also to reduce other factors known to cause PAH disease, like activin A, activin B, and myostatin. There are many other candidates that the company is still working on in its pipeline; however, on April 10th of 2025, the Board decided that the next best move would be to search for strategic alternatives.
The hope of cibotercept was to inhibit signaling pathways that lead to PAH disease, like Activin A and B. Both of these receptors cause an imbalance, and it was believed that by the drug blocking their interaction, it would result in restored balance of these pathways. Along with another pathway as well, known as Bone Morphogenetic Protein, or BMP. The point of this pathway is to control cell proliferation, expansion, and growth into adult tissue homeostasis.
It is not clear whether or not something will end up happening, but the company does have a wide range of options that it could undertake to maximize shareholder value. Such actions that it could possibly do would be to outright sell the company or even just continue to invest in the current pipeline it has, for instance. There actually was a plan to continue to develop cibotercept for the treatment of patients with PAH, but after the company viewed all safety/efficacy data, it felt the best move going forward was just to end this program entirely. The biotech has plenty of cash, roughly $720.5 million as of March 31st of 2025. It noted that it believes this would be enough to operate its business into 2029.
All is definitely not lost despite cutting further development of cibotercept for PAH. The cash on hand is ideal for starters, but even more importantly, it goes back to the fact that there are still other promising candidates being developed. One such candidate is KER-065, which was evaluated in a phase 1 study targeting patients with Duchenne Muscular Dystrophy (DMD). Positive preliminary data was already released from this program, and the company is in talks with regulators to begin a phase 2 study for this particular program. On top of that, there is the advancement of a drug known as elritercept for the treatment of patients with hematological malignancies. Such indications to be targeted with this drug would be myelodysplastic syndrome (MDS) and myelofibrosis (MF). Even better, the advancement of this drug is being done in collaboration with Takeda Pharmaceutical, whereby such a partnership was established back in December of 2024. Keros received a cash payment of $200 million for this collaboration agreement at the beginning of this year in January.