Relay Therapeutics Faces Downgrade Over Efficacy Concerns in Competitive PI3K Inhibitor Market

Monday, Relay Therapeutics Inc. RLAY shared interim data for RLY-2608 from the ReDiscover study of RLY-2608 alone, in combination with fulvestrant, and in combination with fulvestrant and ribociclib or atirmociclib (Pfizer Inc’s PFE selective CDK4 inhibitor).

The clinical benefit rate (CBR) was 57% in heavily pretreated patients. RLY-2608 is a pan-mutant and isoform-selective inhibitor of PI3Kα.

Oppenheimer downgraded Relay Therapeutics, noting the upcoming data from competitors.

“We believe that approved PI3Ks actually manage ORRs between ~20-30% and mPFS in the ~7-8 month range in the real world setting, which is higher than the ~10%/5- mo PFS reported by management,” the analyst writes.

Oppenheimer has downgraded Relay Therapeutics from Outperform to Perform with no price target.

The analyst says the 57% clinical benefit rate is underwhelming, given that the internal bar was 50%. “Perhaps we are being overly critical,” the Oppenheimer analyst writes.

Despite the challenge of cross-trial comparisons due to the heavily pretreated patient group, some critics argue that RLY-2608’s roughly 8x selectivity for mutant PI3K isn’t sufficient.

This could mean Relay is sacrificing efficacy to reduce hyperglycemia risks, thus allowing competitors like Scorpion Therapeutics and OnKure Therapeutics, which have developed more selective drugs, to gain an edge.

“We believe Relay can address key limitations of currently approved targeted agents by reducing off-target toxicity with greater selectivity and by preventing resistance through commonly observed mutations,” Oppenheimer analyst writes.

Price Action: RLAY stock is down 6.94% at $8.85 at the last check on Tuesday.

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