Abstract
9050 Background: Recently reported, extended follow-up data from KEYNOTE-024 or -010 indicates that non-small-cell lung cancer (NSCLC) patients can experience long-term benefit from immunotherapy irrespective of discontinuation (per protocol: 35 cycles ∼24 months) or type of response in computed tomography (CT). Similar results were observed in the pooled analysis of 5-year follow-up data from CheckMate-017 and -057. This raises the question, whether patients may safely discontinue immunotherapy after achieving durable response. However, recently published results from CheckMate-153 demonstrated inferior survival rates in patients ceasing immunotherapy after one year, therefore optimal treatment duration of immunotherapy in advanced NSCLC remains unknown. Protocols from published Phase-III trials implemented treatment for a period of approximately 24 months or until evidence of disease progression or unbearable toxicity. Therefore, the ideal duration of immunotherapy remains unclear, and finding markers of beneficial outcome is of great importance. Here, we determine the proportion of complete metabolic responses (CMR) in patients that have not progressed after 24 months of immunotherapy. Methods: This is a retrospective analysis of forty-five patients with positron emission tomography using 2-[18F]fluoro-2-deoxy-D-glucose (FDG-PET) imaging for assessment of residual metabolic activity after at least 24 months of immunotherapy. Lesion-uptake in FDG PET on or below background level (using mediastinum as reference) was considered as CMR. Time until best objective morphological response including disease stabilization was measured from start of immunotherapy until first stable CT-scan (i.e. no progression or further response compared to previous scan) using RECIST 1.1. Results: Out of 45 patients, 29 patients had a CMR (64%). CMR was observed more frequently in non-first line patients. Patients with CMR were younger (median 65.7 vs. 75.5, P = 0.03). Fourteen patients with CMR have discontinued therapy and have not progressed until time of analysis; however median follow-up was only 5.6 (range 0.8-17.0) months. Conclusions: After a minimum of 24 months of palliative immunotherapy for NSCLC, CMR occurred in almost two thirds of patients. Potentially, achievement of CMR might identify patients, for whom palliative immunotherapy may be safely discontinued.
Published Version
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