KEY TAKEAWAYS
- The phase IV IMbrella A extension study enrolled pts from the IMpower133 trial, undergoing treatment with A+CE to monitor long-term effects for immunotherapy treatments in ES-SCLC.
- The study exhibited a durable survival advantage for up to five years with A+CE.
The Phase III IMpower133 trial reported that first-line treatment with atezolizumab combined with carboplatin/etoposide (A+CE) led to better overall survival (OS) and progression-free survival (PFS) compared to a placebo combined with carboplatin/etoposide (P+CE) for ES-SCLC pts. Upon completion of the IMpower133 trial, those treated with A+CE could join the Phase IV, single-arm IMbrella A extension study. Considering the interest in long-term OS data related to immunotherapy for ES-SCLC, researchers presented patient outcomes from the IMbrella A study as an extension of the IMpower133 findings.
IMpower133 participants could transition to the non-randomized, multi-center IMbrella A extension study if they were still under atezolizumab treatment at the conclusion of IMpower133 and lacked local access to the trial treatment or if they discontinued atezolizumab during IMpower133 and were undergoing survival follow-up. Those in the P+CE group were not eligible to enroll. The IMbrella A study evaluated survival, current treatment status, and safety.
The median follow-up period was 59.4 months for the A+CE group (including both IMpower133 and IMbrella A studies with a clinical cutoff date [CCOD] of 16 Mar 2023) and 26.4 months for the P+CE group (from the IMpower133 study alone; CCOD: 24 Sep 2022). IMbrella A included 18 pts from IMpower133’s A+CE group. The A+CE group showcased a 5-year OS rate of 12% (considering both IMpower133 and IMbrella A) (see Table). Among the 11 pts alive at the data cutoff, the average initial age was 59, four pts had an ECOG PS score of 1, two pts had baseline brain metastases, and none had baseline liver metastases. Details about MD Anderson Cancer Center’s SCLC subtypes, determined through the expression of neuroendocrine (SCLC-A and SCLC-N), non-neuroendocrine (SCLC-P), and immune-infiltrated (SCLC-I) transcriptional markers, were available for seven out of the 11 survivors at 5 years (SCLC-A, n=1; SCLC-I, n=2; SCLC-N, n=4).
The long-term follow-up analysis of IMpower133 participants included in the IMbrella A extension trial offers the first 5-year survival data for pts who were administered first-line cancer immunotherapy for ES-SCLC. This demonstrated that a durable survival advantage for up to five years is achievable with A+CE.
Source: https://cattendee.abstractsonline.com/meeting/10925/presentation/1018
Clinical Trials: https://classic.clinicaltrials.gov/ct2/show/NCT02763579
https://classic.clinicaltrials.gov/ct2/show/NCT03148418
Liu, S.V., Dziadziuszko, R., Sugawara, S., Kao, S., Hochmair, M., Huemer, F., Castro, G., Havel, L., Caro, R.B., Losonczy, G., Lee, J-S., Kowalski, D., Andric, Z., Califano, R., Veatch, A., Gerstner, G., Batus, M., Morris, S., Kaul, M., Siddiqui, M., Li, H., Zhang, W., Nabet, B., Reck, M. Five-Year Survival in Patients with ES-SCLC Treated with Atezolizumab in IMpower133: Imbrella a Extension Study Results.
