FDA starts speedy review of Enhertu in lung cancer

AstraZeneca and Daiichi Sankyo should only have to wait for six months to hear from the FDA if it will approve their HER2 drug Enhertu for non-small cell lung cancer (NSCLC) and add to its current uses in breast and gastric cancer. The US regulator has kicked off a priority review of Enhertu (trastuzumab deruxtecan) as a treatment for NSCLC with HER2 mutations after prior systemic therapy, setting up a decision in the third quarter of this year. It has already given the antibody-drug conjugate (ADC) breakthrough status in HER2-positive NSCLC, a group which accounts for around 2-4% of patients with non-squamous NSCLC but who have no approved HER2-targeting treatments. The mutation drives the spread of the cancer and is generally associated with a much poorer prognosis. While HER2 gene mutations can occur in a range of patients, they are more commonly found in patients with NSCLC who are younger, female, and have never smoked, said AZ. The review will mainly look at AZ and Daiichi Sankyo's DESTINY-Lung01, a phase 2 trial which showed a 55% overall response rate for Enhertu in patients previously treated with platinum chemotherapy, mainly partial responses, with a median duration of response of just over 9 months. The median progression-free survival (PFS) was 8 months and the median overall survival (OS) was around 18 months, which is considered a clinically meaningful result in a patient group with no targeted treatment options. Enhertu is already approved as a third-line treatment for HER2-positive breast cancer and a second-line treatment for gastric cancer, but is poised to move into earlier lines of treatment as well as breast cancer with low HER2 expression levels and is already growing quickly. AZ made $426 million in Enhertu revenues last year, from direct sales and as a share of gross profits with Daiichi Sankyo under the two partners' $6.9 billion licensing deal for the drug in 2019. That was more than double the amount made in the previous year. In February, Enhertu scored its first phase 3 win in HER2-low breast cancer in the DESTINY-Breast04 trial, which analysts at Credit Suisse said could unlock $3 billion in additional sales for the drug. HER2-positive NSCLC is a smaller market, but still sizeable given the very large number of patients who develop lung cancer every year. In the US, lung cancer is the second most commonly diagnosed cancer, with more than 236,000 new cases expected in 2022.