Centessa eyes registration in hemophilia as SerpinPC shows reduction of bleeding in phase 2 study

Centessa Pharmaceuticals' hemophilia drug reduced bleeding rates and spontaneous joint bleeds in a midstage study, setting the biotech up to move the candidate closer to regulatory submission. 

The phase 1/2a study tested three different doses of SerpinPC over 24 weeks in 23 male patients with severe Hemophilia A or B who were not on preventative medications. Hemophilia A and B are blood disorders in which the blood doesn't clot as it should.

The main goal of the trial was to evaluate the safety, tolerability and pharmacokinetics of SerpinPC. Centessa also looked at annualized bleeding rates and spontaneous joint bleeds as exploratory endpoints.

SerpinPC reduced bleeding rates by 88% during the last 12 weeks of treatment at the highest dose, 70% at the mid-dose and 80% at the lowest dose in the proof-of-concept study, Centessa said Thursday. The drug's performance was compared to bleeds the patients experienced prior to receiving the treatment, with each dosing group including seven to eight patients. 

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Spontaneous joint bleeds were lowered by 94% in the highest dose group, 69% in the middle dose group and 76% in the lowest dose.

SerpinPC was well tolerated with all but one of the 23 patients completing treatment. The one patient had a history of a skin disorder and did not finish treatment due to an injection site reaction, Centessa said. The remaining 22 patients have all elected to enroll in a 48-week open label extension of the study, which is expected to read out in the second half of 2022. 

The results were clearly good news for Centessa, an amalgamation of 10 biotechs that just went public in late May. Shares jumped nearly 13.5% to $23.88 a piece as of 12:05 p.m. ET. 

Chief Medical Officer Antoine Yver said the results will allow Centessa to "move SerpinPC into a global development plan aimed at pursuing one or more registrations."

SerpinPC is the second-furthest along candidate in Centessa's pipeline, behind sister company Palladio Bioscience's phase 3 drug lixivaptan for a certain kidney disease. The experimental treatment comes from subsidiary ApcinteX. 

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The drug comes from the serpin family of proteins, hence the name, and is meant to boost production of thrombin by inhibiting activated protein C. Thrombin is the enzyme that causes the clotting of blood.

Hemophilia A and B affect about one in 5,000, and one in 20,000, live male births, respectively.