People with most types of cancer can often mount a good immune response to SARS-CoV-2. This differs for people with blood cancer, but their immune response can compensate and still protect them.
The COVID-19 pandemic has justifiably placed people with cancer under pressure over the past 2 years.
Several studies have shown that people with cancer have a higher risk of severe COVID-19, but researchers could not figure out why – until now.
A new study by international researchers shows that most people with cancer can actually mount an effective immune response to combat COVID-19. However, people with blood cancer and those undergoing immunotherapy have noticeably greater difficulty.
The research, which has been published in Nature Cancer, provides doctors with a reliable scientific basis for advising patients.
“Our data cannot predict the risk of each individual with blood cancer but suggest that people with blood cancer have a higher risk of COVID-19. These people may minimise their risk of becoming infected with SARS-CoV-2 by avoiding places with many people and a higher risk of transmission. In addition, our results and those of others indicate that vaccination will not create nearly as good an immune response for people with blood cancer as for people with solid tumours. The people with blood cancer therefore remain at higher risk of severe COVID-19, even if vaccinated,” explains co-author Annika Fendler from the Francis Crick Institute in London, United Kingdom.
Investigated 118 people with both cancer and COVID-19
The researchers wanted to understand why some people have more severe COVID-19 than the general population and therefore established the CAPTURE study.
Of the 357 people with cancer recruited, 118 tested positive for SARS-CoV-2. The researchers took blood samples from them before, during and after testing positive to determine how their immune system responded.
The researchers defined COVID-19 as a positive PCR test result or by finding S1-reactive or neutralising antibodies against SARS-CoV-2.
The median age was 59 years, 54% were men and 97 (89%) had solid tumours, such as lung, skin, breast and other types of cancer. The remaining 21 participants (11%) had blood cancer.
Many of the participants had other comorbidities that could affect their risk of severe COVID-19: 27% high blood pressure, 21% obesity and 11% type 2 diabetes.
The people with cancer were treated with immunotherapy, chemotherapy, surgery and radiation therapy.
People with solid tumours had a normal immune response
Of the 118 people with cancer infected with SARS-CoV-2, 80% had symptoms, 52 (44%) with mild illness, 36 (31%) moderate illness and 6 (5%) severe illness. Twenty-four (20%) had no symptoms, and 33 (28%) were hospitalised because of COVID-19. Eleven SARS-CoV-2-positive people (9%) died from progressive cancer and two (2%) died from progressive complications of COVID-19.
Based on the blood samples, the researchers found that the immune response of people with solid tumours differed greatly from those with blood cancer.
People with solid tumours had a normal immune response comparable to the general population. However, individuals receiving immunotherapy had a reduced response, which Annika Fendler says may be explained by these drugs modifying the immune response. Whether this reduced response is clinically relevant is still unclear, since the researchers have not yet investigated this.
Blood cancer alters the immune response
People with blood cancer had a reduced antibody response but an increased T-cell response. Otherwise, they had no or very few antibodies in their blood against SARS-CoV-2 during and after infection.
Annika Fendler explains that the results are particularly interesting since they show that people with blood cancer cannot mobilise as many antibodies to combat SARS-CoV-2. Anti-CD20 therapy completely knocks out people’s antibody response.
However, the immune system can compensate for this by triggering a stronger T-cell response to combat SARS-CoV-2. The researchers also found this in the blood samples, which revealed a substantial increase in T-cell response among people with blood cancer.
Annika Fendler says that the results of the blood tests are encouraging. Those with blood cancer tested positive for COVID-19 for a longer time in PCR testing but did not necessarily become more severely ill.
“This indicates that the T cells may compensate for some of the reduced antibody response. In principle, the immune system can remember a T-cell response just as well as an antibody response, so those with blood cancer will also have some immunity after being infected,” she says.
The researchers found that people with cancer had a sustained antibody response for up to 11 months after infection. This indicates that they are well protected afterwards by both vaccination and the immunity generated by infection.
Monitoring people with blood cancer more closely
According to Annika Fendler, the study draws three conclusions with clinical implications.
- Most people with cancer have some immune response to SARS-CoV-2.
- People with blood cancer risk more severe COVID-19 than people with solid tumours because they do not have the same strong antibody response.
- People with blood cancer compensate for part of this reduced antibody response through a stronger T-cell response.
“We did not initially know who would perform better or worse, but we now have a better overview. Our results show that people with blood cancer and people receiving immunotherapy have a higher risk of not mounting an immune response, and doctors must therefore monitor them more closely to ensure rapid treatment if they become infected,” concludes Annika Fendler.
