Can convalescent plasma therapy improve COVID-19 outcomes in patients with hematologic cancers?

By Benedette Cuffari, M.Sc.Reviewed by Emily Henderson, B.Sc.Jun 21 2021

A recent study published in JAMA Oncology discusses the findings of a retrospective cohort study on patients with hematologic cancers who received convalescent plasma therapy following their diagnosis of coronavirus disease 2019 (COVID-19).

Convalescent Plasma Therapy and COVID-19. Image Credit: Orpheus FX/Shutterstock.com

COVID-19 and hematologic cancers

As of June 20, 2021, over 178 million people around the world have been infected by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19. Taken together, COVID-19 has led to the deaths of over 3.8 million people worldwide.

Several comorbidities can make an individual more susceptible to infection by SARS-CoV-2, some of which include diabetes, cardiovascular diseases, and cancer. In particular, patients with hematologic cancers are at a significantly greater risk of both COVID-19 complications and mortality.

Reduced antibody-based immunity in hematologic cancers

Hematologic cancers are often associated with dysfunctional humoral and cellular immune responses, which may contribute to the severe outcomes when individuals with these diseases acquire COVID-19. Plasma cell neoplasms, chronic lymphocytic leukemia (CLL), as well as other lymphoid cancers are specifically associated with impaired antibody function, thus limiting their ability to recover from COVID-19 and even adequately respond to vaccines.

In addition to the immune deficits associated with hematologic cancers themselves, many of the treatments for these diseases can further exacerbate these immune defects. Rituximab, for example, which is a monoclonal antibody that targets CD20 and is often used for B-cell cancers, can lead to lymphopenia and hypogammaglobulinemia. Unfortunately, both these complications of rituximab therapy have been associated with more severe effects of COVID-19.

Convalescent plasma therapy in patients with hematologic cancers

In both the general and older patient populations, antibody therapy using COVID-19 convalescent plasma has proven to be therapeutically effective when administered early in the disease. A recent JAMA Oncology retrospective cohort study discusses whether this same therapeutic approach to treating COVID-19 could also be applied to patients with hematologic cancers.

In their work, the authors analyzed data from hospitalized adults in the United States with a current or previous diagnosis of hematologic cancers with confirmed or suspected SARS-CoV-2 infection between March 17, 2020, to January 21, 2021. A total of 966 patients were found to be eligible for this study, 143 of which received convalescent plasma treatment for their COVID-19 diagnosis, whereas the remaining 823 patients served as untreated controls.

A total of 512 patients of the 966 included in this study had received systemic anticancer treatment within 3 months of their COVID-19 diagnosis. Notably, targeted therapies including monoclonal antibodies, small molecule inhibitors, and other immunomodulatory agents were found to be the most common treatments to be administered to these patients. In fact, the aforementioned anti-CD20 antibody-containing regimen was administered to 115 of the 966 patients.

Patient outcomes

The patients in this study who had received convalescent plasma therapy to treat their SARS-CoV-2 infection were found to be more likely to require aggressive care, with 53.1% of these patients requiring intensive care unit (ICU) admission and 31.5% requiring mechanical ventilatory support.

Additional complications that were found to be more frequent in the patients who received convalescent plasma included bleeding, sepsis, pulmonary complications, and congestive heart failure. Bleeding complications, for example, occurred in 11.2% of convalescent plasma recipients, which is comparable to 4.2% of the control patients. Stark differences were also identified in the frequency of sepsis complications, which occurred in 40.6% of convalescent plasma recipients as compared to 22.4% of the control group.

Of the 966 patients that were included in this study, 23.1% of the patients were reported to have died within the median follow-up period of 30 days. Notably, the mortality rate was found to be significantly lower in plasma recipients as compared to the control group at a rate of 13.3% and 24.8%, respectively. This difference remained statistically significant after adjustment in the overall comparison.

The crude mortality rate was also found to be significantly lower in patients who had received convalescent plasma therapy and were admitted to the ICU as compared to nonrecipients who were also admitted to the ICU. Similarly, nonrecipients who required mechanical ventilatory support were found to have a significantly higher mortality rate as compared to convalescent plasma recipients who also required mechanical ventilation.

Conclusions

The current study confirms the efficacy of convalescent plasma therapy in treating COVID-19 in patients with primary and/or secondary immunodeficient disorders. Several potential mechanisms have been proposed to be responsible for the improved outcomes in treating this patient population with convalescent plasma therapy, some of which include enhanced viral clearance, reduced secondary bacterial and fungal infections, and neutralization of inflammatory cytokines, to name a few.

Although severe complications were reported at a higher rate in patients who had received convalescent plasma therapy, the researchers of the current study believe that this was likely due to the severity of the SARS-CoV-2 infection itself, rather than a result of this treatment approach.