A Roche drug that’s part of a new class of drugs for breast cancer has failed a Phase 2 study, marking the latest stumble in a burgeoning field of oral therapies that degrade a protein key to driving cancer cell growth. The clinical trial results follow disappointing data previously reported by Sanofi and Radius Health, Roche’s main rivals for addressing this cancer target.
The Roche drug, giredestrant, did not meet the main goal of improving how long patients live without their cancer worsening, the Swiss pharmaceutical giant reported Monday in its release of first quarter 2022 financial results. Overall survival data of patients in the Phase 2 study are not yet available. Roche said that results from the study will be presented at a medical meeting later this year.
Giredestrant is a selective estrogen receptor degrader (SERD). The estrogen receptor (ER) is the primary driver of hormone positive breast cancer, which is the most common breast cancer type. The results reported Monday are from a Phase 2 study that enrolled about 300 patients with ER positive, HER2 negative breast cancer that had advanced following one or two earlier lines of treatment. The Roche drug was compared to the physician’s choice of AstraZeneca drug fulvestrant or an aromatase inhibitor, an endocrine therapy used to treat breast cancer.
Fulvestrant validated the approach of degrading ER as a way of treating breast cancers that are positive for that receptor. While that drug has become a blockbuster seller, dosing via intramuscular injection is painful. Also, developers of oral SERDs say their small molecules can achieve better efficacy than fulvestrant. The class of oral SERDs is struggling to live up to that claim.
The disappointing giredestrant results follow Sanofi’s mid-March announcement that its oral SERD, amcenestrant, failed to meet the main goal of improving progression-free survival in a Phase 2 clinical trial. Meanwhile, elacestrant, an oral SERD developed by Radius Health and licensed to Menarini Group, met the main goal of its Phase 3 test in breast cancer last fall. However, Radius shares later fell as a closer look at the data showed the positive data were driven by results in a subgroup of patients.
Roche is pointing to a subgroup of patients as one potential path forward for its oral SERD. Despite the Phase 2 failure, the company said the results show the drug worked better in patients whose cancer has a higher dependence on estrogen receptor activity. The company is also evaluating the drug as an earlier line of therapy for breast cancer patients, a strategy that Sanofi said it was also pursuing.
It’s not the first time that Roche has dealt with disappointing data for an oral SERD. In 2014, the pharma giant paid $725 million up front to acquire Seragon Pharmaceuticals. Three years later, Roche disclosed that it had discontinued Phase 2 development of the lead oral SERD from Seragon.
The promise of an oral SERD that offers better efficacy continues to draw more contenders. Last summer, Pfizer committed $1 billion to begin a partnership with Arvinas, a deal based on encouraging early clinical breast cancer data on that New Haven, Connecticut-based biotech’s drug that employs a mechanism called targeted protein degradation. Meanwhile, New York-based Zentalis is in mid-stage testing with its oral SERD candidate, a small molecule called ZN-c5. Also, Eli Lilly’s Loxo Oncology unit is in early-stage clinical development with an oral SERD called LY3484356.
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