Rigel Pharmaceuticals Stumbles on Midstage Kidney Trial

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Rigel Pharmaceuticals Inc. (NASDAQ: RIGL) saw its shares pull back early on Tuesday after the firm announced topline data from its midstage study. Specifically, this data came from its Phase 2 study of fostamatinib in patients with IgA nephropathy (IgAN), an orphan autoimmune disease of the kidneys.

Ultimately, the trial did not achieve statistical significance for its primary endpoint, which was mean change in proteinuria comparing fostamatinib dose groups to placebo controls in all patients studied.

However, in a prespecified subgroup analysis of patients with greater than 1 gram per day of proteinuria at baseline, the initial data showed a greater reduction in proteinuria in fostamatinib-treated patients relative to placebo patients (this finding did not reach statistical significance). Patients with greater than 1 gram a day of proteinuria have an increased risk of disease progression and represent an unmet medical need.

Further analysis, including histology, is expected later in the year.

Also looking ahead, Rigel plans to seek a pharmaceutical partner to collaborate in the conduct of follow-on clinical studies in IgAN. This partner would take responsibility for the subsequent commercialization of fostamatinib if in an ex-U.S. territory.

Raul Rodriguez, president and CEO of Rigel, commented:

We find the subgroup analysis encouraging because patients and physicians have been challenged to manage this serious disease that has no approved treatment options. This study has provided valuable information on the potential benefit of fostamatinib in IgA nephropathy patients with significant need, those with greater than 1 gram/day of proteinuria. We will continue to evaluate the data to determine the best path forward in this indication.

Shares of Rigel closed Monday at $4.20, with a consensus analyst price target of $6.00 and a 52-week range of $2.14 to $4.71. Following the announcement, the stock was down 8% at $3.24 in early trading indications Tuesday.