Background
Small cell lung cancer is a highly malignant subtype of lung cancer. Staging and prognosis is dependent on the ability to treat all areas of cancer with radiation (limited stage) or not (extensive stage). Patients with extensive stage small cell lung cancer (ES-SCLC) have poor outcomes. The IMpower133 study showed the addition of atezolizumab to platinum and etoposide (EP + atezolizumab) in patients with ES-SCLC led to a modest improvement in both progression free survival (PFS) and overall survival (OS).
It is recognised that there is significant heterogeneity in real world patients compared to a clinical trial. Previously presented results from our group showed that overall and progression-free survival were not improved with the addition of atezolizumab in our centre.
This study aims to show the adverse event rates seen in real world patients treated at an Australian tertiary centre to assess the toxicity of the addition of atezolizumab to EP.
Methods
We retrospectively reviewed ES-SCLC patients who had systemic treatment between 2018 and 2021. Adverse event rates were analysed with descriptive statistics.
Results
61 patients with ES-SCLC underwent treatment at our centre during study period. Total number of adverse events were 65 with EP alone compared to 63 with EP + atezolizumab. However, adverse events of grade 3 or higher with the addition of atezolizumab (25 with EP alone compared to 31 with the addition of atezolizumab). Importantly, there was one patient with grade 4 immune-related pneumonitis and one patient with grade 4 immune-related hepatitis. There were no grade 5 events in either treatment groups.
Conclusions
The addition of atezolizumab did not increase the overall rates of adverse events, but did increase the rates of grade 3 or higher events. This raises questions whether the addition of atezolizumab to small cell lung cancer treatment is warranted given the lack of survival benefits they attained.