What is Covid-19 effect on cancer patients?

Studies on the effects of Covid-19 in cancer patients are still scarce. The few existing studies suggest a higher death rate in Covid-19 cancer patients, however, the actual aspects of cancer and cancer treatment responsible for the increased severity of Covid-19 disease have not been thoroughly investigated yet.

In a recent study published in Nature Medicine, authors report the results of an analysis on 423 cancer patients examined at the Memorial Sloan Kettering Cancer Center.

Main finding. Notably, the study shows that two factors are especially important to predict severe complications in cancer patients: immune checkpoint inhibitors (ICI)-based immunotherapy and age (specifically patients older than 65 years old) were the highest risk factors for severe complications, namely a high risk of patient hospitalization and severe respiratory disease. On the other hand, chemotherapy treatment, metastatic disease and surgery were not associated with worse complications.

Experimental details. Among the 423 cancer patients considered, 40% were hospitalized and 20% developed severe respiratory illness; 9% of them even required ventilation, 12% of them died. Similar to what has been previously observed in the general population, in paediatric cancer patients (only 2% of the all patient cohort analysed), death rate was as low as 12%. Of note, overall, in the same 1-month time period, more cancer patients were hospitalized.

Even though at least one of the main medical conditions previously associated with increased risk of severe disease in the general population, such as diabetes, hypertension, chronic kidney disease and cardiac disease, was present in about 60% of individuals considered, age and ICI treatment were independent predictors of bad outcome.

Furthermore, the analysis of symptoms showed that dyspnoea and diarrhoea were major predictors of severe outcome, while lab markers such as procalcitonin (protein released following infections or tissue damage, used as a marker of sepsis –severe inflammatory response), lymphopenia (low lymphocyte number in the blood), interleukin-6 (protein produced in response to infections and tissue injuries), D-dimer (whose amount reflect clot presence and is associated with the risk of thrombosis) and lactate dehydrogenase (a marker of tissue damage) correlated with subsequent severe respiratory illness.

Previous studies did not find any association between ICI-based treatment and bad outcome, however, in this study severe respiratory illness (e.g. ventilation) was also considered as bad outcome. Nevertheless, the different experimental anti-Covid-19 treatments used were not considered and there is no comparison with a cohort of non-cancer patients.

Conclusions. What is the reason for the increased death rate in patients under immunotherapy ICI-based treatment? Cells of the immune system, such as T cells, produce proteins called checkpoints, which play a role in “controlling” the immune response, ensuring that the immune response is not too strong. However, these proteins sometimes may prevent immune cells to attack and eliminate cancer cells. Immune checkpoint inhibitors are drugs that are able to block checkpoint proteins, thus enabling T cells to attack cancer cells. ICI have been used with success in the treatment of different cancer types, including breast cancer, colon cancer, lung cancer, skin cancer, etc.

Therefore, in Covid-19 patients, ICI treatment might elicit an immune system dysregulation in turn facilitating respiratory distress.

This study suggests increased vigilance for patients with Covid-19 under ICI treatment and points to the need for further studies aimed at thoroughly investigate this correlation.