AstraZeneca and Daiichi Sankyo's Enhertu Shows Promising Results in First-Line Breast Cancer Treatment

AstraZeneca and Daiichi Sankyo have announced groundbreaking results from their phase 3 Destiny-Breast09 trial, positioning their antibody-drug conjugate (ADC) Enhertu as a potential first-line treatment for HER2-positive metastatic breast cancer. The study's outcomes mark a significant advancement in breast cancer therapy, potentially shifting the treatment landscape for newly diagnosed patients.

Destiny-Breast09 Trial Results

The Destiny-Breast09 trial evaluated a combination of Enhertu and Roche's Perjeta against the current standard of care, known as the THP regimen (Perjeta, Herceptin, and chemotherapy). The results demonstrated a "highly statistically significant and clinically meaningful" improvement in progression-free survival across all pre-specified patient subgroups.

According to Susan Galbraith, Ph.D., EVP of oncology hematology R&D at AstraZeneca, this is "the first trial in more than a decade to demonstrate superior efficacy across a broad HER2 positive metastatic breast cancer patient population compared to the current first-line standard of care."

While overall survival data are not yet mature, early trends favor the Enhertu-Perjeta combination. The trial continues, with a second arm testing Enhertu as a monotherapy against THP still ongoing.

Safety Profile and Previous Studies

As Enhertu moves towards potential first-line use, its safety profile remains a key focus, particularly regarding interstitial lung disease (ILD). In the earlier phase 1/2 Destiny-Breast07 trial, 14% of patients receiving the Enhertu-Perjeta combination experienced Enhertu-related ILD events, though none were grade 4 or fatal.

The Destiny-Breast07 trial also showed promising efficacy results, with an 84% confirmed tumor response rate and an 89.4% 12-month progression-free survival rate for the Enhertu-Perjeta combination.

Enhertu's Growing Impact

Enhertu has been rapidly expanding its approved indications. In January, it received FDA approval for second-line treatment of breast cancer with HER2-low or HER2-ultralow expressions, further broadening its patient population.

The drug's success is reflected in its commercial performance, with combined sales by AstraZeneca and Daiichi Sankyo reaching $3.75 billion in 2024, up from $2.57 billion the previous year.

As AstraZeneca and Daiichi Sankyo prepare regulatory submissions for Enhertu in first-line breast cancer treatment, the pharmaceutical industry eagerly awaits the full data presentation at an upcoming medical conference. If approved, Enhertu could potentially redefine the standard of care for newly diagnosed HER2-positive metastatic breast cancer patients.