First-line atezolizumab plus CP/ET offers survival benefits in ES-SCLC

Patients with extensive-stage small cell lung cancer (ES-SCLC) derive real-world clinical benefits from first-line treatment with atezolizumab combined with carboplatin and etoposide (CP/ET), reports a recent study.

This study has also demonstrated the value of time-to-treatment discontinuation (TTD) as a proxy of time-to-treatment failure (TTF), including progression-free survival (PFS), toxicity, and clinical worsening.

“TTD is a real-world outcome that can be used to demonstrate the efficacy of drugs used for administered therapies when duration of treatment is until disease recurrence or unacceptable toxicity,” the investigators said.

“It can be used as an endpoint for real-world evidence studies, where the evaluation is less structured and standardized,” they added.

This observational retrospective study included 79 patients with ES-SCLC treated with atezolizumab plus CP/ET (median age 67.4 years, 58.2 percent males). The Kaplan-Meier method was used to calculate the median TTD, TTF, PFS, and overall survival (OS) in this cohort.

Of the patients, 27 (34.2 percent) had liver metastases, nine (11.4 percent) had brain metastases, and more than half (n=43, 54.4 percent) had other metastasis sites. [J Oncol Pharm Pract 2025;doi:10.1177/10781552241242096]

Treatment cessation

The Kaplan-Meier models showed similar curves for TTD and TTF, suggesting a good concordance of the data extracted by the two different sources. This finding persisted when comparing TTD with PFS curves.

Patients with liver metastases stopped treatment earlier than those with brain metastases (4.4 vs 4.7 months, respectively). The absence of metastases at baseline correlated with a longer TTD.

The median OS was 11.8 months (95 percent confidence interval, 8.6‒15), with a median follow-up of 9.3 months. Patients without a liver metastasis enjoyed a longer median OS than those with one (15.9 vs 6.6 months; p<0.001).

Treatment duration was slightly longer for patients with no liver metastases (6.2 vs 4.4 months; p=0.019), but this did not reach statistical significance.

Notably, patients without brain metastases had a shorter survival time than those with brain metastases (10.4 vs 15.9 months), with no significant differences (p=0.605).

Literature

Looking at existing literature, the median PFS in this cohort was slightly higher than that seen in IMpower133 (6.5 vs 5.2 months). In terms of TTD, the current findings were similar to those reported by a previous study that assessed a real-world cohort of 267 patients (5.9 vs 4.7 months). [J Clin Oncol 2021;39:8561; N Engl J Med 2018;379:2220-2229]

The OS in the current study was slightly lower than that of IMpower133 (11.8 vs 12.3 months), but the median follow-up was also shorter (9.3 vs 22.9 months).

“Overall, the data suggest that real-world clinical benefits were observed in patients with ES-SCLC treated with first-line atezolizumab plus CP/ET,” the investigators said.

“The benefit of immunotherapy in patients with liver metastases seems to be less pronounced but, given that some of these patients also appear to benefit, highlights the need for further research to identify better predictive biomarkers,” they added.