Zai Lab released Phase 1a data Thursday morning as it attempts to compete with a recently approved Amgen drug.
The program, known as ZL-1310, induced a 74% response rate among 19 patients with previously treated extensive-stage small cell lung cancer (ES-SCLC), Zai Lab said. Patients were given the drug as a monotherapy and had received at least one prior chemotherapy treatment that included a platinum-based regimen.
Additionally, all six patients with brain metastases achieved a partial response, a result Jefferies analyst Michael Yee said in a note could help differentiate ZL-1310: The label for Amgen’s drug — the T cell engager Imdelltra — excluded such patients.
Yee also compared the program’s safety results to Amgen’s trial data, noting the small sample size of ZL-1310 patients saw no cytokine release syndrome or ICANS, another kind of cancer therapy toxicity. In a larger sample size of 99 patients, 56% of those who took Imdelltra experienced CRS, while 7% saw instances of ICANS. Only 51% of patients who received the approved dose of Imdelltra saw CRS, and most cases were of low severity, Amgen says.
Zai Lab’s next step is likely to be a Phase 2 study which it could use as a basis for accelerated approval, Yee said, as that’s how Amgen proceeded. Zai Lab has not publicly disclosed a timeline for when such a trial might occur.
Both ZL-1310 and Imdelltra target the delta-like ligand 3, or DLL3. While Imdelltra is a bispecific T cell engager that also binds to CD3, ZL-1310 is an antibody-drug conjugate linking an anti-DLL3 antibody to a topoisomerase 1 inhibitor.
The FDA approved Imdelltra in May for ES-SCLC as the first bispecific T cell engager for a major solid tumor. Boehringer Ingelheim has a similar bispecific T cell engager in early-stage clinical trials, and Novartis and Legend Biotech are collaborating on a DLL3-targeted CAR-T cell therapy.
Zai Lab is also testing ZL-1310 in combination with Roche’s Tecentriq.