Individuals With Cancer Mount an Acceptable Immune Response to COVID-19 Vaccine But Other Strategies Are Needed for Potential Non-Responders

Although most patients with cancer who received both doses of the COVID-19 vaccine developed a good immune response within the following 3 weeks, investigators emphasized the importance of developing alternative strategies for patients who are at a high risk of not responding.

The majority of patients with cancer who received a second dose of the COVID-19 mRNA vaccination experienced a spike in antibody response 3 weeks after, according to a press release from the University of Texas Health Center at San Antonio. However, developing alternative strategies for non-responders will be key, investigators state.1

Although 94% of patients with cancer developed a high rate of seroconversion, patients who are not experiencing an immune response remain a challenge. Notably, 6% of patients who received both doses of the vaccine did not develop antibodies against this disease. Among those who did not respond, those with hematologic malignancies (n = 5/7; 71%) were more likely to not develop anti-bodies following vaccination. Additionally, 1 patient who had no response was either on cytotoxic chemotherapy or rituximab (Rituxan) 6 months prior to the vaccination.

“We could not find any antibodies against the virus in those patients,” Dimpy P. Shah, MD, PhD, of the Mays Cancer Center, University of Texas Health San Antonio MD Anderson, said in a press release. “That has implications for the future. Should we provide a third dose of vaccine after cancer therapy has completed in certain high-risk patients?”

This study enrolled 140 patients who received either the BNT162b2 (Pfizer) or mRNA-1273 (Moderna) vaccines. Investigators determined that 131 patients were SARS-CoV-2–naïve after testing negative for anti-SARS-CoV-2 nucleocapsid protein.2

The median follow-up for the study was 50 days or approximately 22 days after the second dose of the vaccine. The median age at vaccination was 63 years. The majority of patients were 80% non-Hispanic White, 18% Hispanic, and 2% Black. A comparable split of male (55%) and female (45%) patients were noted at both vaccine sites. Additionally, 81% of patients had solid tumors, with breast (33%) and urological cancers (19%) being the most common; other malignancies included gynecologic, skin, thoracic, gastrointestinal, head and neck, brai,n and connective tissue cancers. Additionally, 19% of patients (n = 25) had hematologic malignancies, the most common of which included diffuse large B-cell lymphoma, myeloma, and Hodgkins lymphoma.

Within 6 months of receiving a COVID-19 vaccine, approximately one-third of patients did not undergo anti-cancer therapy. Those who did receive anti-cancer therapy were treated with cytotoxic chemotherapy (23%), endocrine therapy (15%), monoclonal antibody therapy (13%), kinase inhibitor therapy (11%), and immunotherapy (11%).

Additional data from the study indicated that seroconversion was significantly lower following the first dose compared with the second dose (P< .001). Although female patients had significantly higher antibody titers compared with male patients, investigators did not identify any other significant differences in seroconversion rates between age, sex, or race.

There were no statistically significant differences in seroconversion rates and antibody titers (93% vs 95%; P = .678; median interquartile range [IQR], 1232; 95% CI, 258-2,500 vs 2500; 95% CI, 442-2500; P = .254) in those who received the BNT162b2 and mRNA-1273 vaccines, respectively. Notably, patients with hematologic malignancies had lower rates of seroconversion (77% vs 98%; P = 0.002) and antibody titers (median IQR, 832; 95% CI, 24-2500 vs IQR, >2500; 95% CI, 514-2500; P = 0.029) at time point 2 compared with patients who had solid malignancies.

There were significant differences in antibody response associated with the various anti-cancer treatment modalities. Those who received no therapy or endocrine therapy had the best outcomes with high the seroconversion rates ranging from 98% to 100% and a median antibody titer over 2500 U/mL.

Within 6 months of the first vaccine dose, compared with those who were on clinical surveillance (no therapy; median IQR, 152; 95% CI, 2-2500), significantly lower levels of antibody titer were noted in patients who were treated with cytotoxic chemotherapy (median IQR, 611, 160-1956; P = .019) and monoclonal therapy (median IQR, 152; 2-2500; P = 0.029). None of the patients who received anti-CD20 antibody demonstrated seroconversion.

Investigators also looked at patients who had prior COVID-19 exposure. Of the 9 patients who had been previously exposed to the virus, 6 received mRNA-1273 and 3 received BNT-162b2. Most patients in the cohort were older than 55, were female (67%), non-Hispanic White (78%), and had no solid tumor (67%). After the first dose, anti-S titer response was robust (median IQR, 2238; 95% CI, 696-2500]) and second dose (median IQR, 2500; 95% CI, 1376-2500).

During this study, there were no patients who tested positive for SARS-CoV-2 infection. 

“With other vaccines and infections, patients with cancer have been shown not to develop as robust an immune response as the general population,” senior coauthor Ruben Mesa, MD, FACP, executive director of the Mays Cancer Center, concluded in the press release. “It made sense, therefore, to hypothesize that certain high-risk groups of patients do not have antibody response to COVID-19 vaccine.”


1. 94% of patients with cancer respond well to the COVID-19 vaccines. News release. University of Texas Health Science Center at San Antonio. June 30, 2021. Accessed August 12, 2021.

2. Addeo A, Shah PK, Bordry N, et al. Immunogenicity of SARS-CoV-2 messenger RNA vaccines in patients with cancer. Cancer Cell. 2021;39(8):1091-1098.e2. doi:10.1016/j.ccell.2021.06.009

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