Given the lack of a more nuanced understanding as to which of the cancer-related variables impact outcomes from COVID-19, patients with cancer have been advised to receive SARS-CoV-2 vaccines independent of details of their cancer diagnosis or treatment. be administered at a minimum of 2?weeks before or after chemotherapy administration for optimal benefit to the patient. The ideal timing for vaccination remains, however, highly controversial. With regard to safety of influenza vaccination in patients undergoing anti-programmed cell death protein-1 (PD-1) therapy (nivolumab or pembrolizumab), Chong showed no increase in incidence or severity of immune-related adverse events (IRAEs) within either approximately 2 months of ICI treatment or in newly treated patients. Indeed, the IRAE rates were comparable to those from published clinical trials and did not vary with order of administration. SARS-CoV-2 vaccines: specific considerations in patients with cancer Patients with cancer are at increased risk of developing severe COVID-19 and will therefore likely derive substantial benefit from vaccination against SARS-CoV-2.21 43 44 Seminal phase 3 trials leading to Emergency Use Authorization of vaccines against SARS-CoV-2 have largely excluded patients with cancer.9 15 The increased risk from COVID-19 that is associated with a cancer diagnosis is likely determined by a host of variables including the type of cancer, the stage, the specifics of the cancer-directed therapy, and non-cancer-related comorbidities, among others. Given the lack of a more nuanced understanding as to which of the cancer-related variables impact outcomes from COVID-19, patients with cancer have been advised to receive SARS-CoV-2 vaccines independent of details of their cancer diagnosis or treatment. There is also a PDGFRA concern that the immunosuppressive states in patients with cancer may be conducive to evolution of SARS-CoV-2 in a given host, thereby promoting the emergence of variants, providing further support to prioritize patients with cancer for SARS-CoV-2 vaccination.45 Studies investigating the efficacy, immunogenicity, and safety of SARS-CoV-2 vaccination in patients with cancer both prospectively and retrospectively have been initiated at a number of institutions around the world. Many of these studies include systemic efforts to assess vaccine-specific humoral and cellular immune responses including their strength and duration. Results from VU591 these studies are expected to provide insights into how SARS-CoV-2-specific immune responses induced by vaccination are impacted by anticancer therapies including radiotherapy and systemic treatments such as chemotherapy, targeted therapy, immunotherapy, or hormonal therapy. The immune modulatory effects of cancer-directed therapies that VU591 are not primarily designed to target the immune system have recently come VU591 into focus as these non-immune anticancer interventions are being tested extensively in combination with ICIs and other VU591 immunotherapies. In the context of cancer vaccines, there is evidence that frequencies of immunosuppressive myeloid cells are elevated in patients with cancer and that chemotherapy can have a favorable impact on the strength of vaccine-induced immune responses as well as clinical benefit by reducing CD14+HLA-DR+myeloid-derived suppressor cells (MDSCs).46 The sequencing of chemotherapy in relation to vaccination had an impact on the extent of MDSC numbers reversal. In the context of ICI, recent preclinical studies have demonstrated that PD-1 pathway blockade can compromise the formation of vaccine and/or vaccine-specific memory T cells, raising the potential concern that ICI may compromise the generation of durable SARS-CoV-2-specific T cell responses.47C49 From a clinical evaluation, BNT162b2 mRNA COVID-19 vaccine appears to have a good short-term safety VU591 profile in patients with cancer treated with ICIs.50 While these systematic studies will provide important new insights relevant to cancer immunology and related fields, at this point they do not have any practical relevance; there are a number of practical aspects that will (and should) primarily drive decision-making as it relates to SARS-CoV-2 vaccinations for patients with cancer. In other words, while it will be interesting to learn about vaccine-induce immune response in specific cancer.