Study Design and Rationale for Espera Trial: A Multicentre, Randomized, Phase II Clinical Trial Evaluating the Potential Efficacy of Adding SBRT to Pembrolizumab-Pemetrexed Maintenance in Responsive or Stable Advanced Non-Squamous NSCLC After Chemo-Immunotherapy Induction

Background: Improvement in radiotherapy techniques and expected outcomes, as well as in understanding the underlying biological mechanisms contributing to its action (immunomodulation in primis), led to the integration of this therapeutical approach in the current management of advanced non-small cell lung cancer (NSCLC), not only in oncogene-driven tumors, but also in non-oncogene addicted NSCLC where the combination of platinum-based chemotherapy plus pembrolizumab represents nowadays the pivotal strategy. In this light, we have designed a randomized phase II (ESPERa) trial to evaluate the efficacy and safety of adding Stereotactic Body Radiotherapy (SBRT) to pembrolizumab-pemetrexed maintenance in advanced NSCLC patients experiencing disease response or stability after chemo-immunotherapy induction. Patients and methods: Advanced non-oncogene addicted NSCLC patients with ECOG performance status of 0 or 1, who obtained disease response or stability after 4 cycles of platinum-based chemotherapy plus pembrolizumab will be randomized 2:1 to receive pembrolizumab-pemetrexed maintenance plus SBRT vs pembrolizumab-pemetrexed alone. The primary endpoint is progression-free survival (PFS). Concomitant translational researches will be performed to identify potential prognostic and/or predictive biomarkers, as well as to analyze and monitor tumour microenvironment and tumor-host interactions. Conclusions: Although available data suggest the safety and efficacy of combining immunotherapy and radiotherapy, their systematic integration in the current first-line landscape still remains to be explored. If the pre-planned endpoints of the ESPERa trial will be achieved, the addition of SBRT to pembrolizumab-pemetrexed maintenance as a strategy to consolidate and ideally improve the awaited benefit could be considered as a promising strategy in NSCLC undergoing first-line therapy, as well as an interesting approach to be evaluated in other disease setting, as well as in other oncological malignancies where immunotherapy represents nowadays the standard-of-care.