Angela Loizidou

Purpose This systematic review and meta-analysis aimed to evaluate the immune response to anti-SARS-CoV-2 prime-vaccination in patients with cancer. Methods We performed a systematic literature search using PubMed, Embase, and Cochrane Library until 28/09/2021, and conference proceedings from ASCO and ESMO 2021 annual meetings. We screened for observational or interventional studies including subjects ≥ 16 years old with cancer diagnosis who were vaccinated against SARS-CoV-2. Prime-vaccination was defined as one dose of Ad26.COV2-S vaccine or two doses of BNT162b2, mRNA-1273, ChAdOx1-S or inactivated SARS-CoV-2 vaccine. The outcomes were humoral and adaptive immune responses (proportion of subjects with positive titers of antibody anti-SARS-CoV-2 spike protein and anti-SARS-CoV-2 cellular responses, respectively). Results We included 89 records reporting data from 30,183 subjects. The overall seropositive rate within the first month after complete anti-SARS-CoV-2 prime-vaccination was 80% [95% confidence interval (CI), 72–86%], 60% (95%CI, 53–67%) in patients with hematological malignancies (HM) versus 94% (95%CI, 88–97%) in patients with solid malignancies (SM). The diagnosis of HM was significantly associated with a lower seropositive rate on multivariate meta-regression (odds ratio 0.35, 95% CI 0.18–0.69, HM versus both, p = 0.002). The overall humoral response was 49% (95% CI, 42–56%) after incomplete prime-vaccination and 79% (95% CI, 70–86%) at 2 months after complete prime-vaccination. These responses were also lower in patients with HM at these time points. The overall cellular response rate at any time after vaccination was 61% (95% CI, 44–76%). Conclusion This meta-analysis provides compelling evidence of humoral and adaptive immune responses against SARS-CoV-2 in patients with cancer, which last for at least 2 months following complete prime-vaccination.

1537 Background: Patients (pts) with cancer are at increased risk of severe COVID-19. Both underlying malignancy and anti-cancer treatments influence the immune system, potentially impacting the level of vaccine protection achieved. Methods: A systematic literature search of PubMed, Embase, CENTRAL and conference proceedings (ASCO annual meetings and ESMO congress) up to 28/09/21, was conducted to identify studies reporting anti-SARS-CoV-2 spike protein immunoglobulin G seroconversion rates (SR) at any time point after complete COVID-19 immunization (mRNA- or adenoviral-based vaccines) in cancer pts. Complete immunization was defined as 1 dose of JNJ-78436735 vaccine or 2 doses of BNT162b2, mRNA-1273 or ChAdOx1 nCoV-19 vaccines. Subgroup analyses were performed to examine the impact of cancer diagnosis, disease stage, and anticancer therapies on the SR. Overall effects were pooled using random-effects models and reported as pooled SR with 95% confidence intervals (CI). Results: Of 1,548 identified records, 64 studies were included in this analysis reporting data from 10,511 subjects. The Table shows the SR in the overall population and specific subgroups. In pts with solid malignancies (SM), disease stage and primary site did not significantly impact the SR. In pts with hematologic malignancies (HM), SR were significantly lower in pts with chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL) compared to acute lymphoblastic leukemia (ALL), Hodgkin lymphoma (HL), and multiple myeloma (MM). Concerning the impact of cancer therapies on SR, pts with SM undergoing chemotherapy had numerically lower SR (N = 1,234, SR 87%, CI 81-92) compared to those treated with immune checkpoint inhibitors (N = 574, SR 94%, CI 88-97) or endocrine therapy (N = 326, SR 94%, CI 86-97) with or without another targeted therapy. Pts with HM treated with anti-CD20 therapy (within the last 12 months: N = 360, SR 7%, CI 2-20; or more than 12m: N = 175, SR 59%, CI 35-80), immune-modulating agents (BTK or BCL2 inhibitors) (N = 462, SR 47%, CI 32-64%) or other immunotherapies (anti-CD19/CART or anti-CD38) (N = 293, SR 37%, CI 23-53) had lower SR compared to pts treated with autologous (N = 353, SR 77%, CI 67-85) or allogenic stem cell transplantation (N = 509, SR 77%, CI 68-84). Conclusions: SR varies between cancer types and anticancer therapies with some cancer pts having low protection against COVID-19 even after complete vaccination.

1543 Background: Patients (pts) with cancer have increased mortality from COVID-19 and their vaccination is crucial to prevent severe infection. We aimed to identify demographic and laboratory determinants of humoral immune responses to COVID-19 vaccination in pts with cancer and investigate differences in responses based on the vaccine platform. Methods: We searched for records in PubMed, Embase, and CENTRAL up to 28/09/21, as well as conference proceedings from ASCO and ESMO 2021. We included studies of pts ≥16 yr with a cancer diagnosis, who were vaccinated against SARS-CoV-2. Studies were excluded if ≥10% of the participants had other causes of immunosuppression or baseline anti-SARS-CoV-2 spike protein antibodies (Ab)/previous COVID-19 (PROSPERO ID: CRD42021282338). For this subgroup analysis of studies that reported a proportion of pts with cancer and positive Ab titers at any timepoint following complete vaccination, a random-effects model was used to estimate the humoral response rate (HRR) with 95% confidence intervals (CI). Results: We included 64 records, reporting data from 10,511 cancer pts. The HRR in the overall population and by subgroup are shown in Table. Elder patients with hematologic cancers (59%, CI 47-70%, N = 667) and patients with lymphopenia (50%, CI 25-75%, N = 111) or hypogammaglobulinemia (36%, CI 19-57%, N=226) were the subgroups with lower HRR. Male (77%, CI 69-84%, N = 2,659) and Asian (84%, CI 54-96%, N = 37) pts showed a trend to lower HRR when compared with females and other races, respectively. Pts vaccinated with mRNA vaccine platforms (79%, CI 74-83%, N = 9,404) had numerically higher HRR than those receiving the adenovirus vaccines (28%, CI 19-40%, N = 74). Conclusions: This study highlights demographic and laboratory determinants of weaker immune responses to SARS-CoV-2 vaccination, permitting better identification of more vulnerable pts. Despite the small number of pts included receiving adenovirus vaccines, these data also suggest prioritizing mRNA platform vaccination in pts with cancer. [Table: see text]

Background: Immunocompromised cancer patients are presumed to be at high risk of developing COVID-19 infection. Predisposing factors to contracting COVID-19 and to severe outcomes have been described in registries but were not compared between solid tumors and hematological malignancies. Method: This retrospective single oncologic center study included adults with solid tumors or hematological malignancies referred to testing by naso-pharyngeal swab for a SARS-CoV-2 RT-PCR from March 10 to May 18, 2020. Results: A total of 212 patients were included in the study. Forty-five (21%) were tested positive with SARS-CoV-2. The univariate analysis with positive SARS-CoV-2 PCR as a dependent variable reveals significant odds ratios (ORs) for age—with a mean of 62.5 years—(OR: 1.05, 95% CI: 1.02–1.08), performance status ≥2 (OR: 2.38, 95% CI: 1.22–4.70), inpatient status (OR: 2.36, 95%CI: 1.11–4.91), and hematological malignancies (OR: 2.48, 95% CI: 1.23–4.96). In contrast, OR for solid tumors reveals a negative association (OR: 0.40, 95% CI: 0.20–0.81). When integrating severe outcome (ICU admission or COVID-19-related death) as a dependent variable, the univariate logistic regression model shows significant ORs for pre-existing lymphopenia (OR: 4.0, 95% CI: 1.17–15.04), hematological malignancies (OR: 3.73, 95% CI: 1.09–13.80), and a negative association for solid tumors (OR: 0.27; 95% CI: 0.07–0.92). Conclusion: In patients referred for SARS-CoV-2 testing, hematological malignancies were associated with a higher risk of COVID-19 infection and severe outcomes. Other factors were age and inpatient status.