How effective are COVID-19 vaccines for people with myeloma?

This study investigated how people with myeloma responded to vaccines against COVID-19. It found that roughly half of the patients with multiple myeloma (MM) and most patients with other types of myeloma had protection against serious illness after the vaccine. The response to the vaccine was weaker for patients using certain treatments, particularly belantamab mafodotin (Blenrep).

Vaccines have reduced the frequency of COVID-19 illness and allowed people to resume daily activities. However, people with weakened immune systems do not always respond as well to vaccines. For people living with myeloma, the response to COVID-19 vaccines is of concern.

MM is a slow-growing cancer of the plasma cells, a type of white blood cell. Cancerous myeloma cells in the bone marrow can crowd out healthy white blood cells, weakening the immune system. Chemotherapy and other treatments can further weaken the immune system. Because of these immune effects, COVID-19 is more serious in people with MM. 80% of people with MM who contract COVID-19 will require hospital treatment.

There are also earlier stages of abnormal plasma cells, which may later become active myeloma. These earlier conditions include monoclonal gammopathy of undetermined significance (MGUS) and smoldering myeloma (SMM). As myeloma progresses from MGUS to SMM to MM, the immune system typically becomes weaker. It is not clear how patients with myeloma or its precursor conditions respond to COVID-19 vaccinations.

This study included 276 patients with plasma cell conditions. These included 213 patients with active MM, 38 with SMM, and 25 with MGUS. These patients were compared to 226 people without cancer. The patients and healthy volunteers had similar ages, genders, and body weights. The patients and volunteers received either the Pfizer-BioNTech (BNT162b2) or the Astro-Zeneca (AZD1222) vaccine against COVID-19. Their levels of antibodies against COVID-19 were measured before getting the vaccine, 22 days after the first dose (before the second dose of the BNT162b2 vaccine), and 50 days after the first dose.

A neutralizing antibody titer of at least 50% indicates protection against severe COVID-19 disease. After 50 days, the plasma cell patients had significantly lower antibody titers than the healthy volunteers (62.8% vs. 90%). 53.5% of MM patients with active symptoms developed antibody levels above the threshold to protect against COVID-19. For patients with SMM, 60.5% developed antibody levels above the protective threshold. Patients with MGUS (85%) had similar antibody titers to healthy volunteers.

Certain myeloma treatments decreased the response to the COVID-19 vaccine. Patients treated with belantamab mafodotin had low COVID-19 antibody levels (28.2%). Patients using treatments targeting CD38 such as daratumumab (Darzalex) also had lower antibody titers (45.4%). Patients using other myeloma treatments had a significantly higher COVID-19 antibody titer which would protect against disease (62.8%).

Common side effects from the vaccine included pain or redness at the injection site, tiredness, and fever. Side effects were not related to people’s antibody response to the vaccine.

This study found that after a COVID-19 vaccine, people with myeloma produce fewer protective antibodies than healthy volunteers, but it still protects against severe disease for the majority of patients. Certain myeloma treatments including belantamab mafodotin can reduce the response to the vaccine.

Multiple parts of the immune system are involved in protection against disease. Antibodies are created by B-cells, which are affected by both myeloma and its treatment. This study did not measure T-cell response, which is also involved in immune protection but is less affected by myeloma.

The study authors suggest timing COVID-19 vaccination for in-between myeloma treatments if possible, and the continued use of masks and social distancing.