Why Rigel Pharma Is Falling

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Rigel Pharmaceuticals Inc. (NASDAQ: RIGL) shares slid on Thursday after the company announced results from its late-stage clinical trial for its treatment of adult chronic/persistent immune thrombocytopenia (ITP). Unfortunately, the clinical program for fostamatinib did not achieve a statistically significant difference from the placebo.

However, patients who actually met the primary endpoint benefited substantially and typically did so within weeks of initiating treatment, providing early feedback as to whether fostamatinib may be a viable option for treating their ITP.

In the combined data sets, the frequency of patients who achieved a stable platelet response was statistically superior in the fostamatinib group than in the placebo group in all subgroup analyses: prior splenectomy or not; prior exposure to TPO agents or not, demonstrating that the effect of fostamatinib is consistent across various clinical and treatment backgrounds.

But this was still not enough.

The most frequent adverse events were gastrointestinal-related, with no new or unusual safety issues uncovered.

Raul Rodriguez, president and CEO of Rigel, commented:

We believe that the totality and consistency of data from the FIT Phase 3 program, which included two Phase 3 studies and one long-term extension study, strongly supports a clear treatment effect, with a sustained clinical benefit of fostamatinib. We are encouraged by these results and believe that the risk/benefit ratio for fostamatinib is positive for patients with chronic/persistent ITP, a population with a serious unmet medical need.  As a result, we will continue to pursue this opportunity. Our next step is to seek feedback from the FDA.

Excluding Thursday’s move, Rigel has performed more or less in line with the broad markets, with the stock up about 6% year to date. Over the past 52 weeks, the stock is up more than 10%.

Shares of Rigel were last seen down 25% at $2.41 on Thursday, with a consensus analyst price target of $8.25 and a 52-week trading range of $1.88 to $4.38.

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