An experimental pill developed by KalVista Pharmaceuticals succeeded in a Phase 3 trial, giving the drug a chance to become the first oral “on-demand” treatment for people with the rare swelling disorder hereditary angioedema. In a statement Tuesday, KalVista said the drug, sebetralstat, met the study’s main and secondary goals, reducing the severity of swelling attacks significantly faster than did a placebo. Participants on sebetralstat first felt relief from symptoms a median of 1.6 hours after receiving a low dose and 1.8 hours after a high dose, within range of available, injectable medicines. KalVista also said, without offering specifics, that the drug had a safety profile “similar to placebo.” No serious treatment-related adverse events occurred, and no patients left the trial because of side effects. The company plans to file for U.S. approval in the first half of 2024 and later this year in Europe and Japan. Though hereditary angioedema, or HAE, is a rare condition estimated to affect one in 50,000 people globally, the disease has become a crowded area of drug research. Multiple medicines exist to either treat or prevent the disease’s hallmark swelling attacks, which can last for days if untreated and affect a variety of organs. All are limited in some way, however. Acute treatments such as Takeda’s Firazyr and Pharming Group’s Ruconest can require several injections each episode. Preventive options, like BioCryst Pharmaceuticals’ Orladeyo, reduce the rates of attacks, but don’t ward them off entirely. Mid-stage study results reported in 2021 and published in The Lancet last year indicated Kalvista’s drug might fulfill that promise, with symptom relief occurring between 1.5 to 2 hours. That finding made the company’s Phase 3 study, a larger trial, closely watched by analysts and investors. Shares climbed by about one-third this year in anticipation.
While KalVista only disclosed summary findings in its press release Tuesday, they suggest the drug has met analysts’ expectations. The median time to symptom relief observed is close to what was reported in testing of Ruconest and Firazyr, and within a “bull case” previously outlined by Leerink Partners analyst Joseph Schwartz. In a recent survey of 44 HAE specialists, analysts at the investment bank Jefferies reported that specialists want an oral drug that could relieve symptoms sooner than 2.5 hours. A quarter of those surveyed said they’d switch their patients to Kalvista’s drug if it proved as effective as Firazyr. Jefferies analyst Maury Raycroft has estimated the drug can generate about half of a billion dollars in peak yearly sales in the U.S. and Europe. “We set a high bar for an oral therapy to deliver on the efficacy that is seen with approved injectable products, while also improving on the side-effect profile and treatment burden associated with injectables,” said CEO Andrew Crockett, in an email to BioPharma Dive. “These Phase 3 data delivered on that promise, and in many ways surpassed it.” Still, the company didn’t share details that could help determine its competitive positioning versus injectable drugs as well as Pharvaris’ rival treatment. Among them are more granular details on the size and speed of its effects. Detailed results will be presented at a medical meeting later this month.