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HomeMarketGilead Data Raise New Questions About Cancer Therapy

Gilead Data Raise New Questions About Cancer Therapy

New data on a cancer drug trial from Gilead Sciences and Arcus Biosciences are resurfacing debate around the class of cancer drugs known as anti-TIGITs.

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David Paul Morris/Bloomberg

New data on a cancer drug trial from
Gilead Sciences
Arcus Biosciences
are resurfacing debate around the class of cancer drugs known as anti-TIGITs, and raising new questions about the future of a once-promising area of cancer drug development.

Late Monday, Gilead (ticker: GILD) and its partner Arcus (RCUS) said that a new analysis of a Phase 2 trial had found that adding an anti-TIGIT drug called donvanalimab to an established type of cancer drug, an anti-PD1 monoclonal antibody, had improved progression-free survival in non-small cell lung cancer patients.

The results come more than half a year after the failure of a
Roche Holding
(RHHBY) anti-TIGIT in a Phase 3 trial rocked the biopharma sector. Roche’s drug, called tiragolumab, had produced promising data in a Phase 2 study, but the May failure, and another Phase 3 failure for the drug announced in March, shook investor faith in anti-TIGIT drugs overall.

The new results from Gilead could breathe life back into investors’ anti-TIGIT hopes. But the Phase 2 data is complicated, and preliminary, and Wall Street responses were mixed late Monday and early Tuesday.

Shares of Arcus, a smaller biotech, is down 32% in Tuesday trading, while Gilead stock is down 3%. The companies will present the full results of the trial at a scientific conference late Tuesday.

In a note late Monday, Jefferies analyst Michael Yee called the data “hard to interpret.”

“Although today’s data are technically ‘positive’ and show TIGIT combos better than monotherapy PD1 alone, the data are not better than others ahead of them nor compared to Roche Phase II,” Yee wrote. He rates Gilead stock at Buy with an $85 price target.

Other analysts had more upbeat takes. Yigal Nochomovitz of Citi Research wrote that the reduced risk of disease progression or death was “clinically meaningful.” 

“We need to respect the randomization of the study which points to TIGIT driving an efficacy benefit over PD-1 alone,” Nochomovitz wrote. He rates Arcus stock at Buy with a $42 price target.

For Arcus, analysts said that investor expectations had been particularly high in advance of the release.

Anti-TIGIT drugs are intended to help a patients’ immune system attack tumors, and had been discussed as the next generation of immuno-oncology treatments.
‘s (MRK) Keytruda, an anti-PD-1 inhibitor, has had a dramatic impact on cancer therapy since it was first approved in 2014; investors had hoped that anti-TIGITs would be the next big step.

Gilead and Arcus’s trial compared patients who received only zimberelimab, Arcus’s experimental anti-PD-1, with patients who received zimberelimab plus the anti-TIGIT domvanalimab. Another group of patients received those two drugs plus a small molecule drug called etrumadent.

The median progression-free survival for the domvanalimab plus zimberlemiba group was 12 months, compared to 5.4 months for the zimberelimab alone group.

Analysts noted that the performance of zimberelimab alone was worse than expected, as compared to other anti-PD-1 inhibitors. That could raise questions about whether zimberelimab is less effective than Keytruda,
‘s anti-PD-1, which could have an impact on the comparison between the trial’s arms.

The big question is whether the positive outcomes of the donvanalimab trial will translate into the Phase 3 trial, which so far has not been the case with Roche’s tiragolumab.

Despite this year’s anti-TIGIT disappointments, Roche has an ongoing Phase 3 trial of tiragolumab. Merck is also running a late-stage trial of its own anti-TIGIT drug. 

Phase 3 data from Gilead and Arcus won’t come for years. In the meantime, more Roche data are expected next summer.

Write to Josh Nathan-Kazis at


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