Patients with Cancer Should Get COVID-19 Vaccine, Study Says


A seroconversion rate of 94% was identified in a diverse cohort of patients with cancer who had received the COVID-19 vaccine.

High rates of seroconversion in patients with cancer were associated with the COVID-19 vaccination in a new study published in Cancer Cell1. The data indicate the vaccine helps enable optimal treatment delivery among this population, although those with hematologic malignancies and those previously treated with immunotherapy appear to be less responsive.

When utilizing a validated antibody assay against the SARS-CoV-2 spike protein, investigators revealed a high seroconversion rate of 94% among 200 patients with cancer in New York City who had received a full dose of 1 of the FDA-authorized COVID-19 vaccines.

Patients with solid tumors experienced an impressive seroconversion rate of 98% compared with a rate of 85% in those with hematologic malignancies, 70% in those who had received highly immunosuppressive therapies like anti-CD20 agents, and 73% in those who had previously undergone stem cell transplantation. Notably, patients who received treatment with immune checkpoint inhibitors or hormonal therapies experienced seroconversion rates of 97% and 100%, respectively, following vaccination.

“We saw very encouraging [data] showing that most patients with a cancer diagnosis have a really high chance of responding to vaccinations—as long as the vaccinations are done in an appropriate manner, [with] both doses administered,” Balazs Halmos, MD, MS, study author, director of Thoracic Oncology, and director of Clinical Cancer Genomics at Montefiore Medical Center, told OncLive® in an exclusive interview on the research. “This was [true] even for [patients who were receiving] active treatment with chemotherapy, targeted therapy, or immunotherapy.”

Halmos and colleagues launched this study to develop a better understanding with regard to the immunogenicity of vaccines in a group of patients with a cancer diagnosis in New York City by examining the rates of anti-spike immunoglobulin G (IgG) antibody positivity after receiving 1 of the 3 authorized COVID-19 vaccines.

A total of 213 patients were enrolled to the study through an informed-consent process. Twenty-nine additional patients with cancer who received the SARS-CoV-2 spike IgG testing were identified through retrospective chart review.

A total of 18 patients did not have this test conducted following consent, and thus, they were excluded from the analysis. Twenty additional patients were excluded because they had their test done before having received full vaccination in accordance with FDA guidance. Four additional patients were excluded for other reasons.

As such, 233 patients with cancer were noted to have received all required doses of their COVID-19 vaccine; all these patients were included in the safety analysis. A subset of 200 patients received the IgG test and were included in the immunogenicity analysis. Serological information from these patients were utilized in association studies between cancer subtypes and therapies.

Investigators also examined the link between the quantitative titer of SARS-CoV-2 spike IgG and cancer subtypes and therapies. If the 200 patients, 185 had available IgG titers that were at least 2 days following the last vaccine dose. A total of 15 patients were excluded from the vaccination cohort with titers; these patients had received the vaccine, but titers were checked less than 1 week from their last dose.

Among those included in the efficacy analysis (n = 200), the median age was 67 years (range, 27-90), 58% were female, and 42% were male. The study population was noted to be representative of the diverse population that resides in the Bronx, New York, with 32% of patients identifying as African American, 39% as Hispanic, 22% as Caucasian, 5% as Asian, and 3% as other ethnicities.

Additionally, 67% of patients had a solid tumor diagnosis and 33% had a hematologic malignancy. Among those with solid tumors, 26% had breast cancer, 14% had gastrointestinal cancer, 9% had genitourinary cancer, 5% had gynecologic cancer, 13% had thoracic or head and neck cancer, 1% had skin or musculoskeletal cancer, and 1% had carcinoma of an unknown primary. Among those with hematologic malignancies, 13% had lymphoid disease, 9% had myeloid disease, and 11% had plasma cell disease.

Seventy-five percent of patients had an active malignancy and 67% were receiving active treatment at the time that they received the COVID-19 vaccine. Fifty-six percent of patients were on active chemotherapy. Moreover, 19% of patients were on active chemotherapy within 48 hours of receiving at least 1 of their COVID-19 vaccine doses.

Fifty-four percent of patients completed vaccination with the Pfizer vaccine, 31% with the Moderna vaccine, and 10% with the Johnson & Johnson vaccine. A total of 3 patients had received a complete mRNA vaccination series but the information regarding the type of vaccine (Pfizer vs Moderna) are not yet available.

Additional findings from the study showed that significantly higher titer values were observed in solid tumors vs hematologic malignancies among a subgroup of 185 patients with available IgG titers longer than 7 days post vaccination, at a median of 7858 AU/mL vs a median of 2528 AU/mL, respectively (= .013).

When comparing patients who were receiving active cancer treatment vs those who were not, no significant differences in seroconversion were reported, at 96% and 93%, respectively. However, investigators did report lower seropositivity rates in those who were on active cytotoxic chemotherapy versus other treatments, at 92% vs 99%, respectively (= .04). Moreover, significantly lower seroconversion rates were also noted in those who received immunosuppressive therapies like stem cell transplant (73%; = .0002), CD20 antibody therapy (70%; = .0001), or CAR T-cell therapy (all seronegative; = .0002).

Significantly lower titer levels were observed in patients who received CD20 antibody therapy vs the overall patient population, which underscored the susceptibility of patients receiving these treatments during the pandemic.

No statistically significant associations between age, ethnicity, time since immunosuppressive therapy, steroid use, or treatment within 48 hours of a vaccine dose, and seropositivity were reported.

Although all patients who were receiving CDK4/6 inhibitor treatment demonstrated positive anti-spike IgG test results, notably antibody titers were noted to be “very low” in this subset (n = 5), at a median of 1242 AU/mL vs a median of 6887 AU/mL in the overall cohort. “Given the known involvement of the CDK4/6 pathway in immune activation, this might be biologically plausible and warrants further studies into the impact of CDK4/6 inhibitors on vaccine efficacy,” the study authors noted.

A trend to lower titers were also reported among subsets of patients who received BCL-2 or BTK inhibitors.

Among a subset of 22 patients with cancer who had previously been infected with COVID-19, the seroconversion rate was 95%. Notably, antibody titers in those who had prior infection with the virus were found to be significantly higher than those who did not have a known prior infection, at a median of 46,737 AU/mL and a median of 5296 AU/mL, respectively (< .001).

“Our study, along with other emerging data, strongly highlights the continued need to vaccinate patients with a cancer diagnosis urgently and broadly, as vaccinations are likely to be highly effective,” the study authors concluded. “On the other hand, our study highlights at-risk cohorts of patients, in particular patients with hematologic malignancies following receipt of immunosuppressive therapies such as stem cell transplantation, anti-CD20 therapies, and CAR T-cell treatments. These cohorts of patients could potentially benefit from passive immunization with anti-COVID antibodies in the face of the ongoing pandemic.”


  1. Thakkar A, Gonzalez-Lugo JD, Goradia N, et al. Seroconversion rates following COVID-19 vaccination among patients with cancer. Cancer Cell. 2021;39(8):1081-1090.e2. doi:10.1016/j.ccell.2021.06.002

This article was originally published on OncLive as “Study Calls for COVID-19 Vaccination in Patients With Cancer to Enable Optimal Treatment Delivery During Pandemic”

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