AstraZeneca’s oral selective estrogen receptor degrader (SERD) Etcamah missed its main goal in the SERENA-4 trial, creating an obstacle for its broader use as a first-line treatment in HR-positive, HER2-negative breast cancer. The drug, which received approval the prior week for patients with ESR1 mutations when combined with a CDK4/6 inhibitor, demonstrated only a numerical improvement—not one strong enough to be statistically meaningful, in progression-free survival (PFS) when tested across a wider patient group, including those without the mutation.
The SERENA-4 trial compared Etcamah plus Ibrance (palbociclib) to anastrozole plus Ibrance, the current standard treatment. Though the experimental combination showed better trends, the findings did not meet the threshold required to expand the drug’s approved use beyond its current indication for ESR1-mutated patients. AstraZeneca had aimed for the trial to establish Etcamah as a more general frontline option, potentially boosting annual sales toward its $5 billion projection.
In a statement, Susan Galbraith, AstraZeneca’s oncology research leader, highlighted the drug’s established effectiveness in ESR1-mutated cases while stressing the importance of ESR1 testing to determine appropriate treatment.
This setback reflects broader difficulties faced by competitors in the SERD category. Orserdu (elacestrant) and Inluriyo (imlunestrant), both approved for second-line treatment of advanced HR-positive, HER2-negative disease with ESR1 mutations, have not yet secured frontline approvals. Roche’s giredestrant, another SERD, also fell short in the persEVERA trial, a study mirroring SERENA-4—though it showed promise in the adjuvant lidERA trial.
The SERENA-4 failure does not erase Etcamah’s potential. Its approval for ESR1-mutated patients remains valid, and its mechanism, degrading the estrogen receptor, provides a clear advantage over aromatase inhibitors, which often lose effectiveness over time. The CAMBRIA trials may further define its role in early-stage disease, where unmet needs remain. The results reveal a clear pattern: SERDs may not outperform existing treatments in general patient groups, pushing the focus toward targeted strategies based on biomarkers.
For the time being, Etcamah’s development will likely concentrate on more precise patient selection, prioritizing those most likely to benefit, rather than broad approvals. The SERENA-4 outcome, though disappointing, reflects a larger trend: oncology’s shift toward precision medicine requires careful trial design.
In separate news, AstraZeneca shared mixed findings from the DESTINY-Lung04 trial of Enhertu (trastuzumab deruxtecan) in HER2-positive non-small cell lung cancer. The drug improved six-month progression-free survival by 37% compared to Keytruda (pembrolizumab) plus chemotherapy, but overall survival (OS) favored the control group (33.1 months versus 29.3 months). AstraZeneca noted that the OS data were not yet finalized, leaving questions about Enhertu’s long-term effectiveness in this patient population.
