Nine months after filing their Enhertu follow-up Dato-DXd with the FDA, Daiichi Sankyo and its antibody-drug conjugate (ADC) partner AstraZeneca have taken the agency’s advice and pulled their lung cancer application to try their luck in a related indication.
Datopotamab deruxtecan, or Dato-DXd for short, is a TROP2-directed ADC from the same production line that delivered the blockbuster Enhertu. The FDA accepted an application for Dato-DXd as a treatment for non-squamous non-small cell lung cancer (NSCLC) back in February.
That application was based on data from the phase 3 TROPION-Lung01 trial that showed that median progression-free survival (PFS)—one of the study’s primary endpoints—was 5.6 months in patients treated with Dato-DXd versus 3.7 months among those treated with the chemotherapy docetaxel.
Despite these positive data, it was already clear at the time that TROPION-Lung01 wouldn’t deliver a clean sweep for the companies, with a lack of PFS benefit for squamous NSCLC leading to the more limited indication of non-squamous NSCLC only.
Those concerns were heightened in May when the companies revealed the high-level overall survival (OS) results from the same trial, which “numerically favored” Dato-DXd but “did not reach statistical significance.” We later learned that among the non-squamous subgroup, the OS figures for Dato-DXd and docetaxel were 14.6 months and 12.3 months, respectively, missing the threshold for statistical significance.
Now, after considering feedback from the FDA, the companies have decided to voluntarily withdraw the non-squamous NSCLC application. In its place, they have submitted a fresh application specifically for EGFR-mutated NSCLC, according to a Nov. 12 press release.
This new application is based on TROPION-Lung05, an ongoing phase 2 trial that has enrolled 137 patients globally. The study is due to read out in the second half of next year, although the companies said it would reveal results from a pooled analysis of patients with previously treated EGFR-mutated NSCLC at the ESMO Asia Congress next month.
The application will also draw on data from TROPION-Lung01 as well as TROPION-PanTumor01, which is assessing the ADC across a range of cancers.
“TROPION-Lung01 was designed to test the potential to improve upon standard-of-care chemotherapy in a broad, previously treated, advanced lung cancer patient population, AstraZeneca’s executive vice president of oncology R&D Susan Galbraith, Ph.D., explained in this morning’s release.
“The results, together with data from TROPION-Lung05, showed an especially pronounced benefit for patients with an EGFR mutation which informed our discussions with the FDA and the decision to seek accelerated approval of datopotamab deruxtecan in this patient population,” Galbraith added.
The shift in lung cancer strategy for Dato-DXd shouldn’t come as a complete surprise. As far back as February, David Fredrickson, EVP of AstraZeneca’s oncology business unit, told Fierce Biotech that if the OS data from TROPION-Lung01 didn’t meet expectations, “that would be a separate review discussion that we'd have with the [FDA], obviously.”
The companies are continuing to keep their options open when it comes to Dato-DXd, with seven phase 3 trials in lung cancer and five phase 3 studies in breast cancer that are evaluating the ADC both as a monotherapy and in combination with other anticancer treatments like Tagrisso.
In fact, Dato-DXd has another shot at the regulatory goal in the form of an approval application for HR-positive, HER2-negative breast cancer. The FDA is expected to make a decision on that in the first half of next year, according to AstraZeneca’s third-quarter earnings presentation this morning.