Safety of COVID-19 mRNA Vaccines in Patients with Cancer Enrolled in Early-Phase Clinical Trials

SIMPLE SUMMARY: We investigated for the first time the safety profile of COVID-19 vaccines in patients receiving new antineoplastic agents in early-stage clinical trials, including new immuno-regulatory anti-cancer investigational compounds and drug combinations. We found that about three-quarters of the patients under active anticancer treatments experienced mild to moderate adverse effects (AEs) related to COVID-19 vaccines. Patients enrolled in early-phase trials or receiving experimental immunotherapy agents did not experience worse AEs related to the vaccine than patients with cancer not enrolled in these trials, receiving approved drugs. The safety profile of COVID-19 vaccines in patients enrolled in early-phase clinical trials, including those treated with new immune checkpoint inhibitors, does not seem to differ from that of the general population of patients with cancer. Our data support the current vaccine prioritization of all cancer patients with active treatment and calls for data sharing from vaccinated patients enrolled in early-phase clinical trials. ABSTRACT: Pivotal trials of COVID-19 vaccines did not include cancer patients, with questions remaining about their safety and efficacy in this population. Patients enrolled in early-phase clinical trials receive novel treatments with unknown efficacy and safety profiles. Studies on the safety of COVID-19 vaccines in these patients are urgently required. This is a retrospective, real-world, cohort study of patients receiving anticancer treatments and COVID-19 vaccines between 1 February and 25 June 2021 at the Division of New Drugs Development for Innovative Therapies of the European Institute of Oncology. One hundred thirteen patients were enrolled, 40 in early-phase clinical trials, and 20 under novel immunotherapy agents. Nearly three-quarters of the patients experienced at least one adverse event (AE) after the first dose (1D) (74.3%) and second dose (2D) (72.6%). Most of the AEs were local (67.3% 1D and 61.9% after 2D), while 31.8% (1D) and 38.1% (2D) of the patients had systemic AEs. No AEs above grade 2 were observed. Therefore, COVID-19 vaccines appear to be safe in patients enrolled in early-phase clinical trials, including patients receiving novel immunotherapy compounds. All cancer patients should be prioritized for COVID-19 vaccination, regardless of ongoing treatments or enrollment in early-phase trials.