Poster Presentation Clinical Oncology Society of Australia Annual Scientific Meeting 2023

Outcomes of extensive-stage small-cell lung cancer (ES-SCLC) patients treated with platinum doublet and immunotherapy: A Western Australia retrospective review   (#308)

Joann J.L Lee 1 , Wei-Sen Lam 1 , Samantha S.B Bowyer 2 , Ek Leone L.O Oh 2 , Trisha T.K Khoo 2 , Hsing Hwa H.L Lee 2 , Lydia L.W Warburton 1
  1. Medical Oncology, Fiona Stanley Hospital, Murdoch, Western Australia, Australia
  2. Medical Oncology, Sir Charles Gairdner Hospital , Perth, Western Australia, Australia

Introduction

This study compares the outcomes and safety profile observed in IMpower133 trial to standard-of-care first-line treatment for ES-SCLC in a real-world Australian population.

Methods
Retrospective data from two centres in Perth, Western Australia (WA), between January 2020 and March 2023 was collected for patients with ES-SCLC who received atezolizumab plus platinum-etoposide chemotherapy. Outcomes assessed were overall survival (OS), progression-free survival (PFS), objective response rate (ORR) and duration of response (DOR). Incidences of immune related adverse events (irAEs) were also collected. Median OS and PFS were calculated using Kaplan-Meier curves.

Results

This study included 101 patients, with a median age of 68 years. 47 (46.1%) patients had ECOG performance status (PS) of 1. At baseline, 16 (15.7%) and 50 (49.0%) patients had brain and liver metastasis respectively. Median PFS and OS were 5.0 (95% CI 5.4-7.9) and 8.5 months (95% CI 9.3-12.5) compared to 5.2 months (95% CI, 4.4 to 5.6) and 12.3 months (95% CI, 10.8 to 15.9) in IMpower133. 85 patients (84.2%) died at time of analysis. ORR were similar between both populations. Median DOR in our cohort was modestly longer (1.1 months) (Table 1). irAEs were seen in 22.7% (grade ≥3 - 11.9%) compared to 39.9% (grade ≥3 10.6%) in the trial population. Patients who experienced any grade irAE had benefits (p <0.05) in OS and PFS compared to those who did not. (Figure 1).

64cfa57a57c5d-Table+1+Comparison+between+IMpower+trial+to+WA+population.jpg64cfa57a57c5d-Figure+1+OS+PFS+in+WA+population.jpg

Conclusion

Median OS and PFS in our study cohort were shorter than those observed in IMpower133, our patients had higher ORRs and longer DOR. Poor prognostic factors, such as higher ECOG status ≥2 and presence of brain and liver metastases at baseline, likely contributed to shorter OS and PFS in this real-world setting. Presence of irAEs in our patient population showed improved OS and PFS compared to patients without irAEs. The association between irAEs and atezolizumab efficacy in ES-SCLC warrants further investigation.