FDA Grants Priority Review to Enhertu for HER2-Positive Solid Cancers

The Food and Drug Administration (FDA) granted a priority review for a supplemental biologics license to Enhertu (trastuzumab deruxtecan) for the treatment of patients with unresectable (unable to be removed via surgery) or metastatic HER2-positive solid tumors that have been previously treated and have no more satisfactory treatment options, according to AstraZeneca and Daiichi Sankyo, the co-manufacturers of the drug.

“Today’s Priority Review for the first tumor-agnostic submission for Enhertu reflects the potential of this medicine to redefine the treatment of HER2-expressing cancers. Biomarkers for HER2 expression are already established in breast and gastric cancers, but we must now define them across tumor types. We will continue working closely with the FDA to bring this potential first tumor-agnostic HER2-targeted medicine and biomarker to patients as quickly as possible,” Susan Galbraith, executive vice president, Oncology R&D at AstraZeneca, said in a press release.

Enhertu is an antibody drug conjugate that works by targeting and binding to the HER2 protein found on some cancer cells, and then releasing the cancer-destroying component of the agent. The drug was previously approved for certain patients with non-small cell lung cancer and metastatic breast cancer.

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Now, this priority review is based off findings from the ongoing phase 2 DESTINTY-PanTumor02 clinical trial evaluating Enhertu in patients with biliary tract, bladder, cervical, endometrial, ovarian and other cancers.

A primary analysis of the trial was presented at the 2023 European Society of Medical Oncology in October, and showed that the drug led to meaningful benefit in progression-free survival (time from treatment until death or disease worsening), overall survival (time from treatment until death of any cause), objective response rate (percentage of patients whose cancer shrinks or disappears from treatment) and duration of response.

Specifically, median progression-free and overall survival was 6.9 months and 13.4 months, respectively. Median overall survival by cancer type was:

• Endometrial cancer: 26 months
• Cervical cancer: 13.6 months
• Ovarian cancer: 13.2 months
• Bladder cancer: 12.8 months
• Other cancers: 21 months
• Biliary tract cancer: seven months
• Pancreatic cancer: five months

Confirmed objective response rate in the entire patient population was 37.1%, and the median duration of response in these patients was 11.3 months.

The goal of priority reviews is to more quickly fill unmet needs to serious medical conditions. The FDA grants priority reviews to drugs that have the potential to lead to better outcomes than treatment options that are currently available. This specific indication is being reviewed up the Real-Time Oncology Review program and Project Orbis, which are FDA initiatives aimed at bringing better cancer treatments to patients as early as possible, according to the release. The FDA plans to make their approval decision in the second quarter (April through June) of 2024.

“The clinical benefit seen across HER2-expressing metastatic solid tumors in the DESTINY-PanTumor02 trial and ongoing data from the Enhertu clinical development program continues to demonstrate the potential of this medicine beyond its approved indications. If approved, Enhertu could become the first HER2-directed therapy and antibody drug conjugate with a tumor-agnostic indication, providing patients with a potential new treatment option,” said Dr. Ken Takeshita, global head, R&D, at Daiichi Sankyo, said in the release.

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