**7. Therapeutic options in COVID-19 and cancer patients**

Previous studies suggest conflicting results on whether anti-cancer and anti-COVID-19 therapies can be co-administered safely. For example, in over 1000 HCV-positive breast cancer patients, chemotherapy was shown feasible with no significant side effects [37]. However, in another study, ovarian cancer patients undergoing chemotherapy were unable to generate antibody response to the influenza vaccination [38]. Therefore, further efforts are needed to investigate the efficacy and safety of co-administration of anti-cancer and anti-viral drugs and how these outcomes are dependent on the type of cancer, viral infection and therapy.

Vaccination is the most promising approach for preventing a viral infection. Pharmaceutical industries and research organizations across the globe have put great efforts in developing effective and novel vaccine candidates to neutralize SARS-CoV2 virus. Additionally, strategies like repurposing direct preexisting antiviral drugs as well as convalescent serum from COVID-19 recovered patients have been effectively used. Different monoclonal antibodies (mAbs) that recognize the different epitopes on the viral surface may have improved efficacy in neutralizing the SARS-CoV2 virus. IL-6 inhibitors (for example, tocilizumab and siltuximab mAbs) have been used for the management of cytokine storm in cancer patients receiving CAR-T cell therapy. IL-1, a cytokine upstream of IL-6 which is also upregulated in CRS and IL-1 receptor antagonists such as anakinra have been used to treat arthritis patients. Another class of drugs are nontoxic immune-suppressants known as calcineurin inhibitors that impair T-cell function and thereby reduce cytokine levels. Various viral gene components fundamental for the unchecked proliferation of virus in host cancer cells can serve as therapeutic targets for effective anti-viral therapies. Studying these critical viral components will help the researchers to understand the interconnection between the biology of COVID-19-infected cancer versus normal host cells.

The role of various immune cells for example, T cells, and natural killer (NK) cells in understanding the pathology and therapies of cancer and viral infections is becoming more evident with time. This motivates scientists to enhance their understanding and develop novel immunomodulatory therapeutic strategies for co-targeting these diseases. Functional natural killer (NK) cells can produce antiviral responses against influenza infection and are also reported as potential anti-cancer agents. Additionally, due to their negligible graft vs. host signature, NK cells may provide a safer alternative to co-target cancer and COVID-19. Nanoparticles present excellent vehicles for delivering various disease-associated payloads in vivo. Nanoparticles ornated with recombinant human ACE2 protein on their surface may provide an effective therapeutic option for COVID-19 patients. Following binding to the spike protein of SARS-CoV2 virus, ACE2-conjugated nanoparticles may neutralize the virus and prevent it from binding to the ACE2 receptor present on host cells. Conventional anti-cancer treatment strategies, such as chemo or radiotherapy are unable to distinguish between cancer cells and normal cells. This is a significant drawback and leads to toxicities for patients undergoing treatment. Therapies that directly target viral proteins or generate immune responses against infected cells or cancer cells hold promise for effective and tolerable treatment strategies.
