AACR: Adding Roche's Tecentriq to Xtandi doesn't extend lives in prostate cancer—even in subgroups

Pfizer and Astellas’ Xtandi is a mainstay for treating metastatic castration-resistant prostate cancer, and Roche was hoping adding its immuno-oncology med Tecentriq to the mix would improve results even further.

It didn’t.

In a phase 3 study to be presented virtually at the American Association for Cancer Research annual meeting, patients receiving Tecentriq plus Xtandi lived a median 15.2 months, while those taking only Xtandi lived a median 16.6 months.

Subgroup analyses showed no benefit, either—including in those with higher levels of PD-L1, a biomarker that in some tumor types has been an indicator of success for drugs in Tecentriq’s class.

“We are reviewing the data and will use what we’ve learned to inform future studies,” a spokesperson for Roche’s Genentech said by email, adding that while the trial was stopped last year for futility, “biomarker studies are ongoing.”

Members of the PD-1/L1 group of checkpoint inhibitors have yet to really make inroads into prostate cancer, despite their vast success elsewhere. Over the last several years, it’s been anti-androgen drugs Xtandi and Johnson & Johnson nemesis Zytiga grabbing the spotlight. More recently, Zytiga follow-up Erleada—as well as under-review PARP inhibitors Lynparza from AstraZeneca and Merck & Co., and Rubraca from Clovis—have jumped into the field.

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While the PARPs so far have only shown phase 3 success in patients with genetic mutations—specifically, BRCA and ATM mutations for Lynparza, and BRCA mutations for Rubraca—they’ve clearly drawn the attention of immuno-oncology drugmakers, which have been quick to partner on trials.

Bristol-Myers Squibb teamed up with Clovis way back in 2017 for a phase 2 prostate cancer test of Opdivo and Rubraca, while last February, Merck said it would trial its Keytruda alongside Lynparza in a phase 3 study. Merck is also testing Keytruda paired with Xtandi in a phase 3 trial that mirrors the one Tecentriq failed.