On November 19, 2025, the U.S. Food and Drug Administration (FDA) granted full approval to the targeted immunotherapy drug tarlatamab (Imdelltra®) for treating adults with advanced small cell lung cancer (SCLC) that has spread after platinum-based chemotherapy. The approval was based on an international phase 3 clinical trial led by scientist and thoracic medical oncologist Charles Rudin, MD, PhD, of Memorial Sloan Kettering Cancer Center (MSK).
Tarlatamab previously received accelerated approval from the FDA in May 2024 based on results from a phase 2 trial. Its full approval was contingent on the subsequent phase 3 trial. Results from the phase 3 study, which Dr. Rudin published in the New England Journal of Medicine in June 2025, confirmed that tarlatamab works better than standard chemotherapy in patients whose disease has recurred after initial chemotherapy. Specifically, the trial showed the drug’s effectiveness in patients treated with only one prior therapy.
“This FDA approval confirms that tarlatamab is a better option than traditional chemotherapy for most patients with recurrent small cell lung cancer,” says Dr. Rudin, who is Cancer Center Deputy Director and Co-Director of the Druckenmiller Center for Lung Cancer Research at MSK. “More broadly, the data support a new strategy — bispecific T cell engager immunotherapy — as an approach to treating lung cancer.”
How Does Tarlatamab Work?
Tarlatamab is a type of targeted immunotherapy called a bispecific T cell engager, or BiTE. It works by simultaneously latching on to tumor cells and T cells, a type of immune cell. The drug brings the two cell types close together, which stimulates the T cells to kill the adjacent cancer cells.
All 509 patients in the study had advanced SCLC that recurred or progressed after platinum-based chemotherapy. Some patients had also previously received immunotherapy drugs called checkpoint inhibitors.
Half were randomized to receive tarlatamab; the other half received a current standard-of-care chemotherapy.
Analysis showed that patients who received tarlatamab had a 40% reduction in the risk of death compared with those who got chemotherapy. This was true even for patients whose cancer had spread to the brain — an indicator of particularly aggressive disease. Typically, the five-year survival rate for this class of patients has been under 10%.
Importantly, the side effects for patients in the tarlatamab group were less severe than for those who got chemotherapy. Only 19% had to reduce the dose or interrupt treatment due to side effects, compared with 55% of patients in the chemotherapy group. Patients receiving tarlatamab reported significantly reduced symptoms of cough and shortness of breath compared with patients on chemotherapy.
Key Takeaways
- The FDA has granted full approval to tarlatamab, a targeted immunotherapy drug for treating adults with advanced small cell lung cancer (SCLC) that that has spread after platinum-based chemotherapy.
- Tarlatamab had previously received accelerated approval from the FDA based on results from a phase 2 trial.
- The phase 3 trial that led to the drug’s full approval was led by MSK physician-scientist Charles Rudin, MD, PhD.
- That trial showed that patients who received tarlatamab had a 40% reduction in the risk of death compared with those who got chemotherapy.