AZ, Daiichi's Enhertu posts trial win in numerous cancer types. Is a tumor-agnostic approval next?

Already approved in breast, stomach and lung cancers, AstraZeneca and Daiichi Sankyo’s Enhertu has delivered a trial win across many other tumor types that express the HER2 protein biomarker.

Enhertu showed an ability to shrink tumors across multiple HER2-expressing tumors in heavily pretreated patients in a phase 2 trial, the two companies said Monday. The study, coded DESTINY-PanTumor02, has met its target for objective response rate.

The responses are “clinically meaningful,” Ken Takeshita, M.D., Daiichi’s global head of R&D, said in a statement. Besides, the response was durable, according to the partners.

Detailed data will be shared with drug authorities, the two companies said. The 268-patient DESTINY-PanTumor02 trial has seven cohorts, testing Enhertu in biliary tract, bladder, cervical, endometrial, ovarian, pancreatic and rare cancers. Its results could potentially support an FDA approval for Enhertu in heavily pretreated patients regardless of their tumor location.

AZ and Daiichi didn’t immediately respond to a Fierce Pharma request for comment on their regulatory plan.

The FDA has offered tissue-agnostic nods to other cancer drugs based on tumor response data. These prior approvals include Bayer’s Vitrakvi and Roche’s Rozlytrek, both for tumors with abnormal NTRK genes, and several PD-1 inhibitors for mismatch repair deficient or microsatellite instability-high cancers.

Last year, the FDA cleared Eli Lilly’s Retevmo for all cancers driven by alterations in the RET gene. It also approved Novartis’ Tafinlar and Mekinist combo for any solid tumors that have a BRAF V600E mutation.

In October, the FDA released a draft guidance on tumor-agnostic drug development. One requirement asks that drug developers show treatment effects that can be generalized across tumor types based on strong scientific rationale, including the biology of the drug’s target.

For Enhertu, that mechanism lies in its ability to zero in on HER2-expressing tumors and release a toxic payload. The HER2-directed antibody-drug conjugate already has demonstrated impressive efficacy that led to FDA green lights in HER2 breast cancer, non-small cell lung cancer and stomach cancer.

Most recently, Enhertu opened a new chapter in breast cancer treatment by winning the first FDA approval to treat patients with low expression levels of HER2, a subgroup that traditionally had been defined as HER2-negative.

“The DESTINY-PanTumor02 results mark an important step forward in our understanding of the potential role of Enhertu across multiple HER2-expressing tumor types,” Cristian Massacesi, M.D., AZ’s oncology chief development officer, said in a statement Monday.