Effect of antimicrobial therapy on progression free survival of immunotherapy and chemo-/immunotherapy in patients with non-small cell lung cancer

Abstract Background: The choice between immunotherapy with a checkpoint inhibitor (CPI) and chemo-/immunotherapy (CIT) in patients with NSCLC stage IV is often discussed. There is some data that the effect of CPI-therapy is impaired by antimicrobial therapy (AMT). Little is known about the influence of AMT on CIT. Patients and methods: We retrospectively analysed 114 patients (age 68 ± 8.5 y) with NSCLC stage IV. Patients were treated according to the guidelines with either CPI alone (pembrolizumab, nivolumab, atezolizumab, cemiplimab) or CIT (Carboplatin/Pemetrexed/Pembrolizumab, Carboplatin/Paclitaxel/Pembrolizumab). We registered patients’ characteristics including presence and timing of AMT. Group 1 consisted of 42 patients with AMT in the month before CPI or CIT, group 2 were 49 patients with AMT during CPI or CIT, and group 3 were 64 patients without AMT and CPI or CIT. Results: Group 1-3 showed comparable patients characteristics. Using cox-regression analysis, we found that AMT in the month before CPI resulted in a decreased progression free survival (PFS) compared to patients with CPI and no AMT (14 ± 1.02 vs. 4 ± 1.02 months, p = 0.002, 95% CI: 1.88-9). In patients, who were treated with CIT, there was no difference in PFS in those with or without AMT in the month before therapy (10 ± 2.5 vs. 6 ± 1.2 months, p = 0.7). Interestingly, AMT during CIT or CPI therapy showed no effect on PFS. Conclusions: In a real-life setting, we found that AMT reduces PFS when given in the month before CIT therapy. AMT before or during CIT does not seem to influence PFS. As a consequence, AMT before start of therapy might be a factor that could lead to a preference of CIT instead of CPI in NSCLC stage IV patients