Immunological Response to Sars-Cov-2 after Infection and/or Vaccination Among Chronic Myeloid Leukemia Patients - a Prospective Study

Background: Patients with hematologic malignancies have an increased risk of SARS-CoV-2 infection, severe COVID-19, and higher mortality rates due to their immunodeficiency status. We investigated the immunological response to SARS-CoV-2 after infection and/or vaccination.

Methods: We included a cohort of patients diagnosed with Chronic Myeloid Leukemia (CML) in the ongoing prospective study SARS2 SeroPrevalence and Respiratory Tract Assessment (SPARTA) and compared them with a non-cancer group (healthcare providers and community members). We collected saliva and peripheral blood to measure levels of antigen (SARS-CoV-2 viral RNA), antibodies (SARS-CoV-2 IgG, and neutralizing antibodies), and cellular immunology towards SARS-CoV-2. Patients with CML were assessed at the time of each follow-up visit, at least 2 months apart from each other.

Results: From 10-1-2021 to 7-11-2022, we prospectively enrolled 72 participants (34 with CML, 38 non-cancer) with similar sociodemographic characteristics. Most participants had received first (79.4% vs. 78.4%) and second doses (100% vs. 80%) of the COVID-19 vaccine; however, among those vaccinated, a higher percentage of CML patients received a third (61.5% vs. 34.8%) dose.

There was a significant difference in the frequency of previous SARS-CoV-2 infections, where the control group had a higher percentage of patients previously diagnosed with COVID-19 17.64% vs. 84%). Nevertheless, there was no difference in the detection of SARS-CoV-2 antigen at the time of enrollment (0% vs. 5.6%). SARS-CoV-2 antibodies, either IgG or neutralizing (nAB), were detected in most of the participants regardless of cancer status (IgG, 82.4% in the CML cohort and 93.3% in the non-cancer cohort; nAB, 79.4% vs. 88.9%). The two groups had comparable IgG (mean 160.9 vs. 156.3 Ru/ml) and neutralizing (mean 1508 vs. 1463 ng/ml) antibody levels.

Among subjects with antibodies detected, we followed up 18 (10 with CML, 8 non-cancer) after a mean of 94.5 days (Min. 78, Max. 112) from baseline collection. All participants continued having detected antibodies over time. There was no difference in the follow-up measure of IgG or nAB levels between the groups (IgG, mean 173.0 vs. 143.8; nAB 1938 vs. 1573). Analysis after boosters will be performed as our sample increases.

Conclusion: The immunological response to SARS-CoV-2 after infection and/or vaccination among CML patients is comparable to that in non-CML subjects. IgG antibodies and nAB levels decreased over time in all subjects assessed.

Kolhe:Perkin Elmer: Honoraria, Research Funding; Qiagen: Honoraria, Research Funding; Cepheid: Honoraria; PGDx: Honoraria, Research Funding; Illumina: Research Funding; Bioanano INc: Honoraria, Research Funding, Speakers Bureau; Agena: Honoraria, Research Funding. Cortes:Forma Therapuetic: Consultancy; Pfizer: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Biopath Holdings: Consultancy, Current equity holder in private company; Kartos: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Sun Pharma: Consultancy, Research Funding; Bristol Myers Squibb: Consultancy, Research Funding; Gilead: Consultancy.