Roche dumps its PhIII PI3K effort on taselisib after researchers track poor survival edge, harsh side effects for breast cancer

CHICAGO — You can write off another PI3K drug.

Roche has decided to scrap its contender taselisib after investigators reported a slight, 2-month progression-free survival advantage for the drug — along with a sketchy safety profile common to the class — combined with fulvestrant hormone therapy in a Phase III study of metastatic breast cancer.

Here’s what Roche had to say:

The magnitude of benefit observed in SANDPIPER isn’t as strong as we had hoped for and, given the challenging safety profile of this combination and the current clinical landscape, we will not be pursuing an FDA submission for taselisib based on the data presented at ASCO.

José Baselga

Jose Baselga handled the ASCO presentation, outlining the slight edge on PFS against a slate of grade 3 or higher cases of diarrhea (12%), hyperglycemia (10%), colitis (3%), and stomatitis (2%). The adverse events triggered a high rate of discontinuations for the drug combo — 17% versus 2% — and dose reductions for more than a third of the patients in the taselisib arm.

Analysts have been shaking their heads over the PI3K field for years. Gilead’s pioneering Zydelig got slapped with a black box warning on side effects, forcing an end to its quest to complete frontline trials. Bayer’s Aliqopa (copanlisib) was approved last fall for follicular lymphoma patients on the basis of some promising results, crowding a field that Verastem hopes to join with duvelisib, a PI3K dropped by Infinity Pharmaceuticals after AbbVie walked away after getting a glimpse of unimpressive — but still approvable — results.

The potential here, though, is still attracting developers like MEI Pharma, which recently raised $75 million for their registration study. And Roche hasn’t given up on the target. The pharma giant notes:

Still, HR-positive, HER2-negative MBC remains incurable and we are investigating new medicines for it, including other molecules that target PI3K, that we hope could provide more robust efficacy and better tolerability. We remain committed to finding new ways to target breast cancer to help improve outcomes for people with many different types of the disease.

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Research Scientist - Immunology
Recursion Pharmaceuticals Salt Lake City, UT
Director of Operations
Atlas Venture Cambridge, MA

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