The following article features coverage from the 2021 American Society of Hematology Annual Meeting. Click here to read more of Cancer Therapy Advisor’s conference coverage.

COVID-19 vaccines appear less effective in patients with multiple myeloma (MM), according to a retrospective analysis presented at the 2021 American Society of Hematology (ASH) Annual Meeting.

Researchers observed a similar incidence of SARS-CoV-2 infections in vaccinated and unvaccinated patients with MM in the Veterans Affairs system.  

“[V]accination is an effective strategy for preventing SARS-CoV-2, but the effectiveness may be reduced in patients with multiple myeloma, likely due to a co-existing immunosuppression, both due to the disease process as well as associated therapy,” said Nathanael R. Fillmore, PhD, of the Dana-Farber Cancer Institute in Boston, who presented the findings at the meeting. 


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Dr Fillmore and colleagues conducted a matched cohort study of 1636 patients with MM — 818 vaccinated and 818 unvaccinated — and 9596 patients with monoclonal gammopathy of undetermined significance (MGUS) — 4798 vaccinated and 4798 unvaccinated. 

Patients were matched based on age, race and ethnicity, location of the Veterans Affairs facility, rurality of their home address, frailty, and disease type.

For the entire cohort (n=11,232), the median age was 73 years, and 95.3% were men. There were 58.2% of patients who were non-Hispanic White, 34.5% non-Hispanic Black, 3.4% Hispanic, and 4.0% of other or unknown race/ethnicity.

More than half of patients were frail, with 36.3% categorized as very frail and 26.2% as frail. A quarter of patients (25.1%) had a rural home address.

Most MM patients had received MM treatment within the last 90 days — 86.4% among the unvaccinated and 81.2% among the vaccinated. Treatment included chemotherapy, immunomodulatory drugs, proteasome inhibitors, daratumumab, and dexamethasone.

Among patients with MM, there was no significant difference in the cumulative incidence of SARS-CoV-2 infection between vaccinated and unvaccinated patients. 

The estimated vaccine effectiveness in MM patients was 9.7% from dose 1 to the end of the study, 12.6% from dose 2 to the end of the study, and 5.6% from 14 days after dose 2 to the end of the study.

The estimated vaccine effectiveness in MGUS patients was higher than in patients with MM, though it was modest compared with the general population, Dr Fillmore said. 

The estimated vaccine effectiveness in MGUS patients was 28.4% from dose 1 to the end of the study, 34.1% from dose 2 to the end of the study, and 27.2% from 14 days after dose 2 to the end of the study.

The rate of breakthrough infections among vaccinated MM patients was 5.2% in those who had received treatment within the last 90 days, 2.6% in patients whose last treatment was longer than 182 days from vaccination, and 1.1% in patients whose last treatment was between 90 and 182 days before vaccination. 

Patients who received daratumumab within the last 90 days had the highest rate of breakthrough infection, at 9.1%.

“This was just an associative, retrospective study,” Dr Fillmore noted. “Future studies are needed to evaluate the disease state, type/timing of therapy, and determine the role of post-vaccination serologies and boosters in relation to the effectiveness of SARS-CoV-2 vaccination.” 

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.

Read more of Cancer Therapy Advisor’s coverage of the ASH 2021 meeting by visiting the conference page.

Reference

Fillmore NR, La J, Wu JTY, et al. Inadequate SARS-CoV-2 vaccine effectiveness in patients with multiple myeloma: A large nationwide Veterans Affairs study. Presented at ASH 2021; December 11-14, 2021. Abstract 400.