Correlation between natural killer cell activity and treatment effect in patients with disseminated cancer

INTRODUCTION: The aim of the present study was to analyze the possible correlation between Natural Killer (NK) cell activity as measured by the NK Vue assay and treatment efficacy in patients with disseminated cancer. MATERIALS AND METHODS: The study included four trials encompassing palliative treatment, i.e. one trial on prostate- and ovarian cancer, respectively, and two trials on colorectal cancer. The current results are based on 93 patients with mature data on treatment effect. Blood samples were collected at baseline and prior to each treatment cycle into NK Vue. Following 24 hours of stimulation the level of interferon-gamma (IFNγ) in the plasma was measured as a surrogate for NK cell activity. RESULTS: The relationship between NK cell activity and treatment response was similar across tumor types and treatment. The IFNγ either remained at or dropped to an abnormal level (<200 pg/mL) during treatment in group 1 (n = 35). In group 2 (n = 30) the level remained within a normal range (>200 pg/mL), while in group 3 (n = 28) it increased from an abnormal to a normal level. The response rate was 14%, 47%, and 82%, respectively, P < .001. The median progression free survival was 2.6 months (95% confidence interval (CI) 2.1–3.9), 10.0 months (95% CI 6.5–11.1), and 8.3 months (95% CI 6.5–8.7), respectively, P < .001 (log-rank). CONCLUSION: Patients lacking the ability to mount an immune response during the first 2 months of treatment have a poor prognosis, and their clinical benefit of the treatment is questionable.