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KalVista Pharma plans pivotal test after HAE drug posts positive Phase 2 data

One year after losing Merck as a partner, KalVista reports mid-stage clinical data for a pill that could offer an alternative to injectable drugs for a rare, potentially life-threatening disease. KalVista plans to meet with the FDA about proceeding to a Phase 3 study.

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The FDA-approved drugs to treat the acute swelling attacks caused by hereditary angioedema (HAE), a rare inherited disease, are all injectable. KalVista Pharmaceuticals has moved a step closer to offering its oral therapy as an alternative.

The Cambridge, Massachusetts-based biotech on Tuesday released data from a mid-stage study testing its experimental HAE drug, KVD900. According to preliminary results, the Kalvista pill outperformed a placebo and also took effect at a rate comparable to injectable treatments. Based on the data, CEO Andrew Crockett said that the company plans to meet with the FDA to discuss advancing the drug to Phase 3 testing.

HAE is caused by mutations to the C1NH gene, which provides the instructions for making C1 inhibitor, a protein that blocks enzymes associated with inflammation. Patients who have deficient levels or dysfunctional versions of this protein are susceptible to sudden swelling attacks in the extremities and abdomen. When these attacks affect the face and close off the airway, patients are at risk of death.

Drug companies researching HAE therapies have zeroed in different ways of blocking proteins associated with inflammation. Takeda Pharmaceutical’s icatibant, marketed as Firazyr, is a peptide drug that blocks the activity of a protein called bradykinin. Netherlands based Pharming Group sells Ruconest, an engineered version of the C1NH protein that HAE patients lack. Takeda Pharmaceutical markets Kalbitor, a plasma kallikrein inhibitor approved for treating acute HAE attacks. All three are injectables.

Crockett said on the call that the injectable drugs, while effective, are painful and difficult to administer. Consequently, some patients don’t treat their attacks or wait too long to intervene.

KalVista’s drug is designed to block plasma kallikrein. As a small molecule, it can be made in a pill formulation. The company tested its drug in a Phase 2 clinical trial enrolling 68 patients, 53 of which completed the study. The main goal was measuring the time until a patient needed a rescue medication to treat a swelling attack.

After 12 hours, 15 percent of patients treated with KVD900 needed rescue medication compared to 30.2 percent of those who received a placebo, said Chris Yea, the company’s chief development officer. The KalVista drug also worked quickly. Yea said that symptom relief in the group that received the test drug was a median 1.6 hours. Those in the placebo group experienced symptom relief at a median 9 hours. Yea noted that the fast onset of effect is comparable to Ruconest, which takes effect after a median 1.5 hours.

“The results should reassure patients that they can confidently take oral therapy and expect efficacy at least as good as what they’ve become accustomed to with leading injectable therapies, without all the burdens that come with them,” Crockett said.

KalVista reported no serious adverse events and no patient withdrawals from the study associated with such problems. The company said full data from the Phase 2 study will be presented at a future medical conference.

The results so far offer validation for KalVista and its science, which was once partnered with Merck. That collaboration focused on a kallikrein inhibitor for treating diabetic macular edema. The drug failed in a mid-stage clinical trial in 2019; a year ago, Merck declined its option to continue development of the compound.

KalVista said it has already begun preparing for a Phase 3 study for KVD900, pending the outcome of a meeting with the FDA. But the company can’t lay claim to the first oral therapy for HAE. That distinction belongs to Durham, North Carolina-based BioCryst Pharmaceuticals, which won FDA approval for its kallikrein inhibitor, berotralstat, late last year. Marketed under the name Orladeyo, the drug is approved for the prevention of HAE attacks in patients 12 and older.

KalVista is developing a different drug for preventing HAE attacks. Crockett said his company expects to file clinical trial paperwork later this quarter for KVD824, another oral kallikrein inhibitor.

Photo: Martin Barraud, Getty Images

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