COVID-19 vaccines offer protection for multiple myeloma patients, but lesser than other cancer survivors

For patients with the blood cancer multiple myeloma, vaccination against COVID-19 provides some protection against coronavirus infection but to a far lower degree than the general population of cancer survivors, a new study by Dana-Farber Cancer Institute investigators shows.

The findings, to be presented at the 63^rd American Society of Hematology (ASH) Annual Meeting, come as a follow-up to recent research published in the journal JAMA Oncology. In that study, which involved nearly 60,000 patients at Veterans Administration hospitals across the country, researchers found that COVID-19 vaccines are highly effective in patients with cancer, especially among those not currently receiving systemic therapy or hormonal treatments.

For the ASH study, investigators assessed whether these benefits specifically apply to patients with multiple myeloma and to people with monoclonal gammopathy of undetermined significance (MGUS), a symptomless condition that places individuals at increased risk of developing myeloma.

The researchers identified 818 patients with myeloma who had been vaccinated against COVID-19 and an equal number who hadn't and tracked whether they developed the disease. They did the same for 4,798 vaccinated and 4,798 unvaccinated people with MGUS. For comparison, they tracked COVID infection rates in nearly 60,000 vaccinated and unvaccinated cancer survivors who had not been treated with a systemic cancer therapy (such as chemotherapy or immunotherapy) in the previous six months.

They found that, with a follow-up between 14-287 days, the estimated effectiveness of vaccine was 5.6% after two doses in patients with myeloma and 27.2% effective in people with MGUS, compared to 85% in cancer survivors not on treatment in general. (Effectiveness is a measure of the vaccine's ability to prevent infection by the coronavirus responsible for COVID-19.) The researchers also found that the effectiveness of the vaccine begins to decline about six months after patients receive their second dose.

The findings underscore the need for patients with multiple myeloma "to be especially careful – to take social distancing seriously and utilize masking – even if they've been vaccinated," said study senior author Nikhil Munshi, MD, director of basic and correlative science at Dana-Farber's Jerome Lipper Multiple Myeloma Center.

The decreased effectiveness of COVID-19 vaccination in patients with myeloma is likely due to the disease itself and to its treatment, both of which can weaken patients' immune system, researchers say. As the vaccine spurs the immune system to defend against the coronavirus, a decline in immune function can diminish the vaccine's efficacy.

Evidence from the study supports this idea.

We found that, compared to patients who hadn't been treated in the last six months, the rate of breakthrough infections was 2.6%. For patients who were treated within the last 90 days, that number goes up to 4-5%. And in patients treated with daratumumab [an immunotherapy agent], the number was 9%."

Nikhil Munshi, MD, director of basic and correlative science, Dana-Farber's Jerome Lipper Multiple Myeloma Center

The JAMA Oncology study that was the basis for the ASH study utilized data from nearly 60,000 patients at Veterans Hospitals who had received systemic cancer therapy between August 2010 and May 2021.

Researchers compared coronavirus infection rates in 29,152 patients who hadn't been vaccinated against COVID-19 and an identical number of patients who had. They found that 14 days after administration of the second dose of the vaccine, its effectiveness was 85% in patients who hadn't received systemic therapy at least six months prior to vaccination and 76% among those receiving hormone therapy.

Researchers will present findings of this study during Session 652, Abstract 400, on Sunday, Dec. 12 at 10:15 a.m. EST.