Promoting Immunotherapy Efficacy With Low-Dose Liver RT

• 1. Age ≥18 years. 2. ECOG performance status ≤2 (or Karnofsky ≥60%, see Appendix A). 3. Patients must have adequate organ and marrow function to receive standard of care immunotherapy and/or chemoimmunotherapy as per the treating medical oncologist. 4. Must be planning to, and able to, undergo active treatment with PD-L1 or PD-1 checkpoint immunotherapy given per standard care throughout the duration of the RT intervention per their treating physician.
• Note: Patients may receive other SOC CTLA 4 inhibitors or other SOC chemotherapy/immunotherapy in combination with a SOC PD-L1 or PD-1 checkpoint inhibitor and remain eligible. 5. Biopsy proven Non-Small Cell Lung Cancer (NSCLC) or Melanoma. 6. Radiographic evidence of liver metastases. 7. Women of child-bearing potential and men must agree to use adequate contraception (e.g., hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. 8. Ability to understand and the willingness to sign a written informed consent document. Legally authorized representatives may sign and give informed consent on behalf of study participants. 9. Patients must have insurance authorization to proceed with radiotherapy prior to initiation of radiation treatment on study

1. Patients with prior immunotherapy use in the adjuvant setting for NSCLC or Melanoma are eligible unless the adjuvant immunotherapy was delivered within 6 months of enrollment. 2. Patients with NSCLC are ineligible for enrollment in cohort 1 if the presence of the following driver mutations are noted: EGFR, ALK, ROS1, RET. 3. Patients with uncontrolled intercurrent illness or any other significant condition(s) that would make participation in this protocol unreasonably hazardous, in the opinion of the Investigator. 4. Patients with a prior or concurrent malignancy whose natural history or treatment has the potential to interfere with the safety or efficacy assessment of the investigational regimen in the opinion of the Investigator. 5. Pregnant women are excluded from this study considering the use of ionizing radiation.