A late-stage clinical study of Pfizer Inc’s (PFE) Sutent was halted early after the drug showed significant benefit in patients with a rare form of cancer, the drugmaker said on Thursday, sending its shares up 3.5%.

An independent committee monitoring the study recommended halting it after concluding that patients on Sutent stayed free of disease progression for longer than those on placebo plus best supportive care.

The patients in the study had advanced pancreatic islet cell tumors, a rare cancer with limited treatment options, according to Pfizer.

Sutent is currently approved for treating both advanced renal cell carcinoma and gastrointestinal stromal tumors.

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