Abstract 516P
Background
Despite vaccination, COVID-19 could cause severe disease in cancer pts, also including GI tumors. In this context, few data are reported on the immune response to vaccines in pts under systemic treatment.
Methods
This prospective study was conducted on blood samples from 1000 pts admitted to Reggio Emilia AUSL-IRCCS Cancer Center, who were receiving systemic therapies and had ≥ 2 vaccine doses. We provide humoral (IgM-IgG serology and anti-spike antibodies) and cell immune response (B and T lymphocyte counts), also analysing specific lymphocyte subsets on the first 200 pts treated with chemo- (CT) or immunotherapy. We also evaluated the T-cell immune response on the first 50 pts and those with an inadequate anti-spike serologic response by the T-SPOT.COVID test.
Results
Here, we report preliminary data on 85 pts affected by GI cancers, colorectal (n=38, 44.8%), gastroesophageal (n=21, 24.7%) and hepato-biliary-pancreatic (n=26, 30.5%). Most of the pts were male (68.2%), had metastatic disease (74.1%) and received CT (90.6%). We stratified pts in 3 groups according to the time from the last vaccine dose (0-6/6-12/ >12 months), evaluating those receiving CT. We showed no significant cellular and humoral response decrease from the last vaccine dose (Table). Table: 516P
| CD3/CD8 (cells/μl) | CD3/CD4 (cells/μl) | CD19 (cells/μl) | IgG anti spike (mg/dl) | ||
| months | N | Median | Median | Median | Median |
| 0-6 | 16 | 417 | 719 | 61 | 1955 |
| 6-12 | 26 | 343 | 717 | 77 | 2685 |
| >12 | 35 | 403 | 837 | 105 | 2380 |
Age, treatment setting (metastatic vs non-metastatic) and primary cancer site seem not to influence immune response, while we found a trend toward a higher humoral response in male pts and a higher cell response in those previously affected by COVID-19.
Conclusions
The first results of this study in GI cancer pts show that the immune response to COVID-19 vaccines remains good after 12 months from the last dose. The enrollment is ongoing, and we could provide relevant information on the influence of clinical factors on the immune response and identify specific subgroups that could benefit from a different vaccine approach, potentially impacting on public health strategy.
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.