KalVista Reports Positive Results in Trial of Oral Treatment for HAE Attacks

Rare Daily Staff

KalVista Pharmaceuticals reported positive topline data from a phase 2 clinical trial demonstrating statistically and clinically significant efficacy of its plasma kallikrein inhibitor KVD900 as an oral on-demand treatment for hereditary angioedema.

Investors cheered the news, sending KalVista stock up 200 percent in premarket trading.

Hereditary angioedema (HAE) is a rare, genetic disorder that results in recurring attacks of swelling in various parts of the body, including the abdomen, face, feet, genitals, hands, and throat that can be can debilitating and painful. Attacks that obstruct the airways are potentially life-threatening due to the risk of asphyxiation.

The KVD900 phase 2 study was a randomized, double-blind, placebo-controlled, crossover clinical trial evaluating the efficacy and safety of KVD900 as an on-demand treatment for HAE attacks. The trial included 53 adult HAE patients from 25 clinical sites in the United States and Europe with type 1 and type 2 HAE who had had three attacks in the 90 days prior to enrollment. During the first part of the two-part trial, patients received a single, open label 600 mg dose of KVD900 to evaluate pharmacokinetic and pharmacodynamic properties. All patients then entered part two of the trial, which was a double-blind investigation to assess the efficacy of KVD900 compared to placebo in a two‑attack, crossover design. Patients took a single dose of 600 mg of KVD900 or placebo within one hour of the start of the first attack. The second attack was dosed with the alternative crossover treatment. Patients were able to use their conventional rescue treatment, as required.

Topline results showed that attacks treated with KVD900 significantly reduced use of rescue, with 15 percent of KVD900 treated attacks rescued compared to 30 percent on placebo at 12 hours, and the efficacy benefit of KVD900 was maintained at 24 hours.

KVD900 also significantly reduced time to onset of symptom relief on a Patient Global Impression of Change scale (PGI-C), with a median time of 1.6 hours versus 9 hours for attacks treated with placebo.

KVD900 treated attacks also achieved symptom relief more quickly than placebo treated attacks when assessed using a composite Visual Analogue Scale score. Within 12 hours of oral administration, KVD900 significantly increased the number of stabilized or improved attacks when assessed by a Patient Global Impression of Severity scale (PGI-S) or use of rescue. Additional exploratory endpoints were also statistically significant and favored KVD900 treatment over placebo.

There were no serious adverse events reported in the trial and no patients withdrew due to adverse events.

“The rapid onset of symptom relief and significant reduction in the use of rescue medication show that patients can confidently take KVD900 at the earliest signs of an attack and avoid the burden and discomfort of injections,” said Andrew Crockett, CEO of KalVista.

KalVista plans to work with regulatory agencies to advance development of KVD900 as quickly as possible. The company plans to present the full data for the KVD900 phase 2 study at a future medical meeting.

KVD900 has received Fast Track designation from the U.S. Food and Drug Administration and an approved Pediatric Investigational Plan (PIP) from the European Medicines Agency (EMA).

If approved, KVD900 will compete with BioCryst Pharmaceuticals’ Orladeyo, a once-daily oral plasma kallikrein inhibitor approved by the FDA in December 2020 to prevent attacks of HAE in adults and pediatric patients 12 years and older.

Photo: Andrew Crockett, CEO of KalVista.