#SITC18: Another underwhelming performance for STING damages Aduro’s already suffering share price

Aduro Biotech execs $ADRO made as much as they possibly could of the two partial responses researchers tracked among 40 heavily pre-treated cancer patients in an early-stage study of their STING therapy. But their defense at SITC wasn’t nearly enough to save the Berkeley, CA-based biotech from another beating at the hands of unhappy investors.

Stephen Isaacs

Merck set the stage at ESMO last month when researchers acknowledged that their rival STING therapy had no effect on tumors as a monotherapy, raising questions about the class and the drug at Aduro — which Novartis $NVS plunked down $200 million in cash to partner on. 

Aduro CEO Stephen Isaacs called the marginal results for ADU-S100 (MIW815) “promising,” which was a bit of a stretch for his investors. They drove the stock down 14% on Friday. And you can count Brad Loncar — an independent investor in biotech and a regular contributor at Endpoints News — among the growing ranks of skeptics.

Brad Loncar

Loncar’s take: 

The bottom line with STING is that mouse models appear to be entirely non-predictive. The abscopal effect that was so exciting preclinically appears to be at best muted in humans.  Some people were hoping for an ‘ah ha’ moment with this one and that’s not happening unfortunately. It’s too early to completely write it off, and to their credit these are heavily pretreated patients, but count on years of going back to the drawing board for STING.

The companies aren’t about to back down at this stage, though. Researchers are pursuing a Phase Ib with Novartis’ PD-1 spartalizumab (PDR001) to check on any synergies that could exist with the checkpoint crowd — which is where Merck has been focused. And they added an arm to the initial study which matches their STING with Bristol-Myers’ other prominent checkpoint, the CTLA-4 drug Yervoy.

The biotech has had to deal with a string of setbacks, including the abrupt departure of J&J from their partnership a few weeks ago, torching a deal that included more than a billion dollars in milestones. And last year the company had to punt CRS-207, after that drug also performed poorly in trials.

Aduro has also been hit this year by some unexplained departures from the top ranks, including CMO Natalie Sacks, who left at the beginning of October. The CFO, Gregory Schafer, left in March. 

Back at the end of March, their stock traded at a 2018 high of $9.30. Friday’s close at $3.63 leaves the sinking stock down 61% off that mark.

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