AZ/Daiichi's possible breast cancer blockbuster gets fast US review

The FDA has granted a priority review for AstraZeneca and Daiichi Sankyo’s potential breast cancer blockbuster trastuzumab deruxtecan, setting up a possible launch as early as Q2 next year.

Earlier this year AZ asked investors for an extra $3.5 billion to finance a development and collaboration deal with Japan’s Daiichi Sankyo over the HER2- targeting drug.

The deal, involving an upfront payment of $1.35 billion, plus payments of up to $5.55 billion upon achievement of regulatory and other milestones, looks like it is on track.

The companies have high hopes for trastuzumab deruxtecan, which if approved could become a blockbuster with predicted peak annual sales of more than $4.5 billion.

Under the agreement the two companies will split the development and marketing costs as well as global profits from the drug, except for Japan, where Daiichi will retain exclusive rights.

As its name suggested the drug, also in development to treat HER2-expressing gastric tumours, consists of the active ingredient in Roche’s Herceptin (trastuzumab), linked to a cancer-killing chemotherapy agent, deruxtecan.

The rationale is that the antibody-drug conjugate offers a more powerful attack on cancers expressing the HER2 receptor than Herceptin, while leaving healthy cells alone.

AZ said that the FDA has set a decision date on the filing for the second quarter of next year following the Priority Review.

The drug was previously granted FDA Breakthrough Therapy Designation and Fast Track designation, and the filing is based on the combination of data from a phase 1 trial published in The Lancet Oncology, and the pivotal phase 2 DESTINY-Breast01 trial.

Trastuzumab deruxtecan is under review in Japan, with further regulatory filings planned.

The companies are also due to present detailed findings of DESTINY-Breast01 at the San Antonio Breast Cancer Symposium in December.

José Baselga, executive vice president, oncology R&D at AstraZeneca, said: “Trastuzumab deruxtecan has the potential to transform the treatment landscape for patients with HER2-positive metastatic breast cancer who have limited treatment options today. This Priority Review draws on the strength and the consistency of results seen in the phase 1 and phase 2 trials and is a critical step on the journey to deliver this potential new medicine to patients.”