AstraZeneca's Enhertu Posts Substantial Clinical Benefit Over Roche's Kadcyla In Breast Cancer Trials

AstraZeneca Plc (NASDAQ: AZN) and Daiichi Sankyo's (OTC: DSNKY) Enhertu have shown some striking data in late-stage breast cancer trials and early solid tumor tests. 

What Happened: The Phase 3 DESTINY-Breast03 head-to-head study included second-line unresectable or metastatic HER2-positive breast cancer patients who had previously undergone treatment with a Herceptin-chemo combo. The data were presented at the European Society for Medical Oncology Congress (ESMO21) 2021.

Data: Enhertu cut the risk of disease progression or death by 72% compared with Roche Holding's AG (OTC: RHHBY) Kadcyla (trastuzumab emtansine). Median progression-free survival for Enhertu had not been reached at 15.5- and 13.9-month check-ins, compared with a median PFS of 6.8 months for Kadcyla.

On a secondary endpoint of progression-free survival (PFS), Enhertu posted a three-fold increase over Kadcyla at 25.1 months versus 7.2 months, respectively. Enhertu posted a 79.7% ORR in response rate, more than double Kadcyla's 34.2%. 

AstraZeneca and Daiichi reported that 94.1% of patients in the Enhertu arm are still alive at the one-year mark compared with 85.9% on Kadcyla.

The companies also rolled out cohort data from the DESTINY-Lung-01 Phase 2 study showing Enhertu posted a response rate of 54.9% in patients with HER2 mutant non-small cell lung cancer.

At a 13.1-month median follow-up, Enhertu posted a median duration of response of 9.3 months, median PFS of 8.2 months, and median overall survival (OS) of 17.8 months.

There were 24 reported cases of ILD or pneumonitis among 91 patients in the study, including four Grade 3 events and two patient deaths tied to ILD or pneumonitis.

Price Action: AZN stock closed 5.29% higher at $58.50 on Monday.

Check out our coverage of the European Society for Medical Oncology Congress (ESMO21).