Promoting Immunotherapy Efficacy With Low-Dose Liver RT

Patients will continue standard of care immunotherapy (with or without standard chemotherapy). The research aspect of this study will be adding in the Low-Dose Liver Radiation (LD-LRT) before cycles 1, 2, 3 of treatment to see if this improves the treatment effects. The trial will be conducted using Simon's optimal two-stage test in two separate cohorts. Cohort 1 will include patients with NSCLC with liver metastases. Cohort 2 will include patients with melanoma with liver metastases. The primary endpoint is 6-month PFS for each cohort compared separately to historical trials with an effect size goal of 25% improvement in 6-month PFS. Cohort 1 NSCLC- The estimated 6-month PFS in NSCLC with liver metastasis was obtained from a metanalysis of 8 randomized trials evaluating the effect of liver metastases in patients treated with PD-1/PD-L1 inhibitors and chemotherapy (SOC) or chemotherapy alone\[30\]. Based on the pooled hazard ratios we estimate a 0.68 HR and PFS of 30% at 6 months with chemotherapy alone. Assuming underlining exponential distribution for survival time, we estimate the 6-month PFS is 44% in patients with liver metastases treated with PD-1/PD-L1 inhibitors and chemotherapy. Simon's optimal two-stage design (Simon, 1989) will be used for conducting the trial. In cohort 1, the null hypothesis is that the true response rate (6-month PFS) is 0.44, and the alternative hypothesis is that the true response rate is 0.69. The trial is carried out in two stages. In stage I, a total number of 11 patients is accrued. If there are 5 or fewer responses among these 11 patients, cohort 1 will be stopped. Otherwise, an additional 15 patients will be accrued in stage II, resulting in a total number sample size of 26. If there are 16 or more responses among these 26 patients, we reject the null hypothesis and claim that the treatment is promising. The design controls the type I error rate at 0.049 and yields the power of 0.81. The probability of early termination is 66%. Cohort 2 Melanoma with liver met (Expected 6-mo PFS= 30%, Desired 6-mo PFS=55%) The null hypothesis for 6-month PFS of 30%, based on historic clinical trials and series specifically evaluating PFS in patients with melanoma and liver metastases treated with standard of care immunotherapy\[9-11, 14\]. The alternative hypothesis is that the 6-month PFS is 55%. The trial is carried out in two stages. In stage I, a total number of 10 patients is accrued. If there are 3 or fewer responses among these 10 patients, the cohort will be closed. Otherwise, an additional 18 patients will be accrued in stage II for cohort 2, resulting in a total sample size of 28 patients. If there are 13 or more responses among these 28 patients, we reject the null hypothesis and claim that the treatment is promising. The design controls the type I error rate at 0.05 and yields the power of 0.8. The probability of early termination is 65%.