PRIMARY OBJECTIVE:~I. Estimate the T cell-based immune response rate on day 56 post-injection of synthetic MVA-based SARS-CoV-2 vaccine COH04S1 (GEO-CM04S1) vaccine boost administered at 2.5x10^8 plaque-forming unit (PFU) or standard of care (SOC) vaccine administered as standard of care.~SECONDARY OBJECTIVES:~I. Evaluate the safety of single-dose vaccine boost based on moderate and unacceptable toxicities up to day 28 post-injection for the GEO-CM04S1 and SOC vaccines.~II. Estimate the T cell-based immune response rate at day 112 post-injection of GEO-CM04S1 vaccine at 2.5x10^8 PFU vs SOC severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) messenger ribonucleic acid (mRNA) vaccine administered as COVID-19 vaccine boosters.~III. Select the more promising vaccine to study further as a booster in patients with CLL.~IV. Evaluate SARS-CoV-2 S and N-specific Th1 vs Th2 polarization. V. Estimate the magnitude and durability of T-cell-based immune responses over a 12-month period.~VI. Estimate the levels and durability of SARS-CoV-2-specific IgG in a 12-month period.~VII. Evaluate levels of antibodies neutralizing SARS-CoV-2 in original strain and in variants of concern (VOC) based on the Centers for Disease Control and Prevention (CDC) definition using Spike-pseudotyped lentivirus.~VIII. Evaluate the overall safety profile during follow-up (12 months). IX. Estimate the incidence and severity of COVID-19 infection during follow-up (12 months).~EXPLORATORY OBJECTIVES:~I. Determine the SARS-CoV-2 variant by sequencing virus from polymerase chain reaction (PCR)-confirmed infected participants.~II. Evaluate activated/cycling and memory phenotype markers in SARS-CoV-2 stimulated T cells.~III. Estimate SARS-CoV-2-specfic serum IgA levels measured by enzyme-linked immunoassay (ELISA).~OUTLINE: Patients are randomized to 1 of 2 arms.~ARM I: Patients receive GEO-CM04S1 vaccine intramuscularly (IM) on days 0 and 84 on study.~ARM II. Patients receive mRNA vaccine injection IM on days 0 and 84 on study.~Patients undergo blood sample collections throughout the study and are monitored for 1 year.
This phase II trial compares the effect of the GEO-CM04S1 vaccine with the current standard of care vaccine in preventing COVID-19 infections in patients with chronic lymphocytic leukemia (CLL). The GEO-CM04S1 vaccine uses a modified vaccinia virus (MVA) backbone that may be more effective at boosting COVID-19 immunity in patients with poor immune responses. MVA strongly induces T cell expansion (infection fighting blood cells) even in the background of a suppressed immune system, which is the case in the targeted CLL patient population. Using the GEO-CM04S1 vaccine may be more effective at preventing COVID-19 infection in patients diagnosed with CLL.