Benzinga | Apr 13, 2021 07:04AM EDT

Rigel Pharmaceuticals Phase 2 Clinical Trial Of Fostamatinib In Hospitalized Patients with COVID-19 Met Primary Endpoint

Rigel Pharmaceuticals, Inc. (NASDAQ:RIGL), today announced positive topline results from a multi-center, Phase 2 clinical trial to evaluate the safety of fostamatinib, its oral spleen tyrosine kinase (SYK) inhibitor, for the treatment of hospitalized patients with COVID-19.

The trial, being conducted in collaboration with the National Heart, Lung, and Blood Institute (NHLBI), part of the National Institutes of Health (NIH), and Inova Health System, met its primary endpoint of safety. Fostamatinib reduced the incidence of Serious Adverse Events (SAEs) by half. By day 29, there were three SAEs in the fostamatinib plus standard of care (SOC) group of thirty patients compared to six SAEs in the placebo plus SOC group of twenty-nine patients (p=0.23). Of these, there was a reduction for the disease related SAE of hypoxia in the fostamatinib group compared to placebo (1 vs 3, respectively; p=0.29).

"Despite the growing arsenal of vaccines gaining emergency use authorization, COVID-19 continues to spread and patients remain in need of effective therapies. We are extremely pleased with the outcome of this trial, which provides early indications of the potential positive impact of fostamatinib for patients with COVID-19," said Raul Rodriguez, president and CEO of Rigel. "These results are an important addition to the extensive accumulation of data evaluating fostamatinib in COVID-19, which also include the ongoing Phase 2 study with Imperial College London and our own Phase 3 clinical trial being conducted in the U.S. and Latin America."

"Fostamatinib was shown to be well tolerated in hospitalized patients with COVID-19 on oxygen. Taken altogether, the results of this trial suggest fostamatinib may be a useful addition to improve the outcome of severe and critically ill COVID-19 patients who are at the highest risk of death despite treatment with the best conventional therapies under the current standard of care (including remdesivir and steroids)," said Wolfgang Dummer, M.D., Ph.D., Rigel's Chief Medical Officer. "Consistent with the observed clinical outcomes, we are encouraged to see that in patients receiving fostamatinib there was a more rapid decline in a number of inflammatory biomarkers, that have previously been shown to be associated with the course of COVID-19 disease, compared to those receiving placebo."

Key findings from the Phase 2 clinical data readout include:

* At Day 29, in the overall population there were zero deaths in the fostamatinib group of thirty patients compared to three deaths in the placebo group of twenty-nine patients (p=0.07). In more severe patients, those with an ordinal scale assessment of 6 or 7, the difference was zero of nineteen patients compared to three of seventeen patients (p=0.049), respectively.

* There were four intubated patients in the trial on mechanical ventilation (ordinal scale 7) with two patients randomized to each treatment group. Both patients in the fostamatinib group improved within 7 days and came off the ventilator, while both patients in the placebo group deceased.

* Fostamatinib was superior to placebo in accelerating improvement in clinical status by day 15 (mean change -3.6 compared to -2.6, p=0.035) and by day 29 (mean change -4.2 compared to -3.3, p=0.12) using ordinal scale assessments.

* The median number of days in the ICU was reduced by 4 days, from 7 days in the placebo group to 3 days in the fostamatinib group (p=0.07).

* Despite general SOC use of both steroids and remdesivir in all 59 patients, there was a consistently greater reduction in NETosis and other inflammatory biomarkers (CRP, Ferritin, D-Dimer, Fibrinogen) in the fostamatinib group as compared to the placebo group.

Investigators will conduct full and detailed analyses in the coming weeks.

Based on these data, Rigel plans to discuss the potential for emergency use authorization (EUA) with the U.S. Food and Drug Administration (FDA) of fostamatinib as a treatment for hospitalized patients with COVID-19. Fostamatinib, marketed in the U.S. as TAVALISSE(r) (fostamatinib disodium hexahydrate) tablets, is approved in the U.S., Europe, and Canada as a treatment for adult chronic immune thrombocytopenia (ITP).