Blood Test Reveals Who Benefits from New Immunotherapy

New Blood Test Predicts Response to Lung Cancer⁢ Immunotherapy

MADRID, 19 Jan. – Researchers at teh Mass‍ General Brigham ‌Cancer Institute in the United States have identified ‍a specific marker in circulating tumor cells that predicts whether a‍ patient⁤ with ​lung ⁢cancer will experience‍ a ​lasting response ​to a recently⁤ approved immunotherapy drug called tarlatamab.

The findings, published in ‘Cancer Revelation’, ⁤could allow doctors to ‌easily and non-invasively determine which patients should receive the​ drug.

“Isolating cancer cells from⁢ the blood has ⁢enormous‌ potential‌ to guide cancer therapies related to the ​immune system, ‌and‌ our ⁤group has created state-of-the-art bioengineering technologies⁤ for the ⁣purification of these circulating tumor cells,” says ⁣Dr.​ Daniel A. Haber,lead and corresponding ⁤author,and ⁣director of⁣ the Krantz Family Center for Cancer Research at⁢ the Brigham. “We’ve learned a lot about the biology of these cells,‌ but we hadn’t had​ a test with direct clinical relevance. In ⁤this study, we believe we’ve achieved that.”

The‍ blood‌ cell enrichment‍ technology has been licensed⁣ to⁢ TellBio.

The study⁤ focused on whether the properties of ​circulating tumor cells could correlate with a patient’s response to⁤ tarlatamab, which received full approval in late 2025 as ⁢a treatment for small cell lung cancer (SCLC) following ‌prior chemotherapy. Tarlatamab is an antibody that recruits T cells to cancer cells expressing a specific neuroendocrine marker called DLL3.

While tarlatamab showed ​promising results ‌in clinical trials, approximately half of patients with SCLC experience cancer progression within six months of starting treatment.⁣ It was previously believed that all cases of SCLC expressed DLL3, but Dr. Haber ‍and his⁢ colleagues discovered that onyl half of the 20 patients studied had abundant DLL3-positive cancer‍ cells in their blood – and these​ were the⁢ patients who responded to tarlatamab.

Testing for ‌DLL3 in CTCs correctly identified ‍85% of‌ patients who experienced a clinical benefit from the drug and 100% of those who did⁢ not (85% sensitivity, ‌100% specificity).

The study, a collaboration‍ between bioengineers who ⁤developed the technology to analyze rare cancer cells in blood samples and lung cancer specialists, has significant implications for clinical care.

“Our work could ⁢help predict ‍which patients with⁢ SCLC are likely to respond to tarlatamab ⁢and possibly other antibodies targeting DLL3,many of which are in advancement,” ⁤says dr. Justin ‌Gainor, co-author of the study‍ and director of the Thoracic‍ Cancer Center Program at the⁣ Brigham. “It also⁢ has potential implications for other cancers that express DLL3 as they become more aggressive and for the field of antibody-directed cancer​ therapies.”