Adding low-dose radiation to the current standard first-line treatment, durvalumab plus etoposide-platinum chemotherapy, appears to improve survival outcomes in patients with extensive-stage small cell lung cancer (SCLC), suggested new findings from a small, single-arm study.

The analysis, presented at the 2024 European Lung Cancer Congress, revealed that low-dose radiation improved patients’ median progression-free and overall survival compared with standard first-line treatment, reported in a 2019 trial, lead author Yan Zhang, MD, reported.

The standard first-line treatment results came from the 2019 CASPIAN trial, which found that patients receiving the first-line regimen had a median progression-free survival of 5 months and a median overall survival of 13 months, with 54% of patient alive at 1 year.

The latest data, which included a small cohort of 30 patients, revealed that adding low-dose radiation to the standard first-line therapy led to a higher median progression-free survival of 8.3 months and extended median overall survival beyond the study follow-up period of 17.3 months. Overall, 66% of patients were alive at 1 year.

These are “promising” improvements over CASPIAN, Zhang, a lung cancer medical oncologist at Sichuan University, Chengdu, China, said at the Congress, which was organized by the European Society for Medical Oncology.

Study discussant Gerry Hanna, PhD, MBBS, a radiation oncologist at Belfast City Hospital, Belfast, Northern Ireland, agreed. Although there were just 30 patients, “you cannot deny these are [strong] results in terms of extensive-stage small cell cancer,” Hanna said.

Although standard first-line treatment of extensive-stage SCLC is durvalumab plus etoposide-platinum chemotherapy, the benefits aren’t durable for many patients.

This problem led Zhang and his colleagues to look for ways to improve outcomes. Because the CASPIAN trial did not include radiation to the primary tumor, it seemed a logical strategy to explore.

In the current single-arm study, Zhang and his team added 15 Gy radiation in five fractions to the primary lung tumors of 30 patients during the first cycle of durvalumab plus etoposide-platinum.

Subjects received 1500 mg of durvalumab plus etoposide-platinum every 3 weeks for four cycles. Low-dose radiation to the primary tumor was delivered over 5 days at the start of treatment. Patients then continued with durvalumab maintenance every 4 weeks until progression or intolerable toxicity.

Six patients (20%) had liver metastases at the baseline, and three (10%) had brain metastases. Over half had prophylactic cranial radiation. Performance scores were 0-1, and all but one of the participants were men.

Six- and 12-month progression-free survival rates were 57% and 40%, respectively. Overall survival was 90% at 6 months and 66% at 12 months. Median overall survival was 13 months in the CASPIAN trial but not reached in Zhang’s trial after a median follow-up of 17.3 months, with the earliest deaths occurring at 10.8 months.

Grade 3 treatment-related adverse events occurred in 80% of patients, most frequently hematologic toxicities. Five patients (16.7%) had severe adverse reactions to radiation. Although the overall dose of radiation was low, at 3 Gy each, the fractions were on the large side.

Hanna wanted more information on the radiotoxicity issue, but even so, he said that adding low-dose radiation to our durvalumab-chemotherapy doublet warrants further investigation.

Both Hanna and Zhang thought that instead of killing cancer cells directly, the greatest benefit of upfront radiation, and the peritumoral inflammation it causes, is to augment durvalumab’s effect.

Overall, Hanna stressed that we haven’t had results like these before in a SCLC study, particularly for novel agents, let alone radiation.

The study was funded by AstraZeneca, maker of durvalumab. Zhang and Hanna didn’t have any relevant disclosures.

M. Alexander Otto is a physician assistant with a master’s degree in medical science and a journalism degree from Newhouse. He is an award-winning medical journalist who worked for several major news outlets before joining Medscape Medical News. Alex is also an MIT Knight Science Journalism fellow. Email: aotto@mdedge.com



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