Radiotherapy is a mainstay cancer therapy whose antitumor effects partially depend on T cell responses. However, the role of Natural Killer (NK) cells in radiotherapy remains unclear. Here, using a reverse translational approach, we show a central role of NK cells in the radiation-induced immune response involving a CXCL8/IL-8–dependent mechanism. In a randomized controlled pancreatic cancer trial, CXCL8 increased under radiotherapy, and NK cell positively correlated with prolonged overall survival. Accordingly, NK cells preferentially infiltrated irradiated pancreatic tumors and exhibited CD56 dim -like cytotoxic transcriptomic states. In experimental models, NF-κB and mTOR orchestrated radiation-induced CXCL8 secretion from tumor cells with senescence features causing directional migration of CD56 dim NK cells, thus linking senescence-associated CXCL8 release to innate immune surveillance of human tumors. Moreover, combined high-dose radiotherapy and adoptive NK cell transfer improved tumor control over monotherapies in xenografted mice, suggesting NK cells combined with radiotherapy as a rational cancer treatment strategy.

Patients with cancer frequently receive immune-checkpoint inhibitors (ICIs), which may modulate immune responses to COVID-19 vaccines. Recently, cytokine release syndrome (CRS) was observed in a patient with cancer who received BTN162b2 vaccination under ICI treatment. Here, we analyzed adverse events and serum cytokines in patients with 23 different tumors undergoing (n = 64) or not undergoing (n = 26) COVID-19 vaccination under ICI therapy in a prospectively planned German single-center cohort study (n = 220). We did not observe clinically relevant CRS (≥grade 2) after vaccination (95% CI 0–5.6%; Common Terminology of Adverse Events v.5.0) in this small cohort. Within 4 weeks after vaccination, serious adverse events occurred in eight patients (12.5% 95% CI 5.6–23%), six patients were hospitalized and two patients died. Despite absence of CRS symptoms, a set of pairwise-correlated CRS-associated cytokines, including CXCL8 and interleukin-6 was >1.5-fold upregulated in 40% (95% CI 23.9–57.9%) of patients after vaccination. Hence, elevated cytokine levels are common and not sufficient to establish CRS diagnosis.

Cancer patients frequently receive immune checkpoint therapies (ICT) which may modulate immune responses to COVID-19 vaccines. Recently, cytokine release syndrome (CRS) was observed in a cancer patient who received the BTN162b2 vaccine under ICT. Here, we analyzed adverse events (AEs) in patients of various solid tumor types undergoing (n=64) or not undergoing (n=26) COVID-19 vaccination under ICT as an exploratory endpoint of a prospectively planned cohort study. We did not observe clinically relevant CRS after vaccination (95% CI [0,0.056]). Short term (<4 weeks) serious AEs were rare (12.5%) and overall AEs under ICT were comparable to unvaccinated patients. Despite the absence of CRS symptoms, we observed a pairwise-correlated set of CRS-associated cytokines upregulated in 42% of patients after vaccination and ICT (>1.5fold). Hence, clinically meaningful CRS appears to be rare in cancer patients under ICT and elevated serum cytokine levels are common but not sufficient to establish CRS diagnosis.