Study shows efficacy of COVID-19 vaccine in people receiving cancer treatment

People undergoing active cancer treatment, including stem cell transplant, should receive the COVID-19 vaccine, according to a study published in JAMA Oncology. People with cancer are at a higher risk of developing severe COVID-19 and dying from it. These findings provide guidance to a group largely excluded from clinical trials evaluating the efficacy of COVID-19 vaccines. Qamar Khan, MD, professor in the department of Medical Oncology and member of The University of Kansas Cancer Center, led the study, named Cancer therapy and Immunogenicity of COVID Vaccine (CANINE, for short).

Dr. Khan and his team measured antibodies in the blood of 453 participants. Samples were obtained before receiving a messenger RNA (mRNA) vaccine, after the first dose and 1, 3 and 6 months after the second dose. A small number of patients received the Janssen (Johnson & Johnson) vaccine, and their samples were taken three times, up to seven months post-vaccination. Blood samples were also gathered from patients who received an mRNA booster. The team measured binding antibodies, which bind to and destroy the virus' spike protein. They also measured neutralizing antibodies, which stop the virus from infecting healthy cells. The higher the level of antibodies, the better protection we have against COVID-19.

One-third of participants showed no antibody response after the first dose of the vaccine. However, antibody response peaked four weeks after the second dose of the mRNA vaccine and was sustained at six months post-second dose. Overall, 95% of patients achieved a measurable immune response. Eight out of 10 patients remained above the antibody threshold of 100 units per milliliter or higher at six months.

Most importantly, antibodies increased 20-fold after a third (booster) dose, suggesting a "brisk" memory B cell response. Memory B cells stay in the body and evolve after vaccination, improving protection against the virus over time.

We were concerned that memory B cells would not be produced at all because of the immunosuppressive nature of some of these cancer treatments. Instead, participants produced a generous reservoir of memory B cells, which will provide lasting protection against the COVID-19 virus. The booster shot was a game-changer."

Dr. Qamar Khan, MD, professor in the department of Medical Oncology and member of The University of Kansas Cancer Center

The immune system and cancer

Our immune system constantly scans our body for foreign substances, called antigens, that pose a risk to our health. The white blood cells in our immune system make antibodies when threats are detected. Some types of cancers can alter our immune systems. Dr. Khan noted that participants with a blood cancer did not generate as many antibodies as those with a solid tumor.

Cancer treatments, including chemotherapy and stem cell transplants, suppress the immune system. As a result, people with cancer are uniquely – and sometimes severely – immunocompromised. Vaccines, like the COVID-19 vaccine, teach our immune system to identify and attack specific viruses.

The clinical takeaway

A better understanding of how the immune system responds to COVID-19 vaccination could help physicians make informed decisions about vaccinating people undergoing cancer treatment. It could also guide organizations like the Centers for Disease Control to determine vaccine prioritization for patients with cancer.

"There has been some fear about whether people undergoing cancer treatment should receive the COVID-19 vaccine or not, and some cancer patients are still on the fence about COVID-19 vaccines" Dr. Khan said. "These findings tell us that, yes, they absolutely should. If you have a cancer, you can be assured that you're getting protection from the vaccines."