PD1 inhibition effect on immunization with MRNA vaccines against SARS-CoV-2.

Abstract

e14594 Background: We provide care for the rural, low-income, and underserved population of Oroville. The community has a vaccination rate of 50% and booster rate of over 20% in the 3rd year of the ongoing global SARS-CoV-2 pandemic in 2022. During this period, a subset of our cancer patients benefited from the use of immune checkpoint inhibitors. Methods: This is a cross-sectional observational study of the effectiveness of a mRNA-based vaccine in medical care workers compared to patients with systemic malignancies treated with immunomodulation of PD-1 and CTLA-4 inhibitors. The study was approved by the hospital IRB. We evaluated the total anti-Spike protein antibody titer using a commercial semi-quantitative assay, Labcorp Test #164090. All subjects received 3 doses of the mRNA vaccine. We excluded anyone who was administered therapeutic monoclonal antibodies (mAb) or had a recent infection within 120 days. Results: Subjects with systemic malignancies were significantly older, p = 0.0001 by t-test: median age: 76, range: 64-82, compared to health care workers: median age: 52, range: 21-75. Accrual had to be prematurely stopped upon the arrival of Omicron wave in the community. Out of the seven subjects treated with immunomodulation, six received nivolumab, including two in combination with ipilimumab. One subject received pembrolizumab. Six of the subjects had metastatic disease: one was treated adjuvantly for locally advanced esophageal adenocarcinoma. The rest had NSCLC and one case of urothelioma. We divided the groups to those who had the highest titer of antibody versus everybody else and found a similar distribution in both groups using the Chi2 test. The vast majority of the healthcare workers, 24/27 or 89%, had above the upper limit antibody titer. Patients with systemic malignancy, 5/7 or 71%, had above the upper limit antibody titer p = N.S. Conclusions: Three doses of the mRNA vaccine provided high titers irrespective of frailty or age. We hypothesize that immunomodulation could favorably affect vaccination response.