This phase III trial studies immunotherapy and stereotactic body radiation therapy to see how well it works compared with immunotherapy alone after first-line systemic therapy (therapy that goes throughout the body) in treating patients with stage IV non-small cell lung cancer. Immunotherapy with monoclonal antibodies, such as pembrolizumab, may help the body's immune system attack the cancer, and may interfere with the ability of tumor cells to grow and spread. Stereotactic body radiation therapy uses special equipment to position a patient and deliver radiation to tumors with high precision. This method can kill tumor cells with fewer doses over a shorter period and cause less damage to normal tissue. Giving immunotherapy with stereotactic body radiation therapy may work better than immunotherapy alone in treating patients with non-small cell lung cancer.

PRIMARY OBJECTIVES:

I. To compare progression-free survival of patients randomized to radiation and consolidative immunotherapy against those receiving consolidative immunotherapy alone.

SECONDARY OBJECTIVES:

I. To estimate overall survival in all patients and will compare overall survival of those randomized to radiation and consolidative immunotherapy against those receiving consolidative immunotherapy alone.

II. In patients receiving radiation, to describe the rate of in-field local control and rate of out-of-field disease progression with serial imaging.

III. In patients not receiving radiation, describe progression at known sites of disease after first line systemic therapy and rate of development of new metastases with serial imaging.

IV. To evaluate toxicity associated with radiation followed by consolidative immunotherapy.

OUTLINE: Patients are randomized to 1 of 2 arms.

ARM I: Patients undergo 3-10 treatments of stereotactic body radiation therapy (SBRT). Patients also receive pembrolizumab intravenously (IV) over 30 minutes every 3-4 weeks for 1 year at the discretion of the treating physician.

ARM II: Patients receive pembrolizumab IV over 30 minutes every 3-4 weeks for 1 year at the discretion of the treating physician.

After completion of study treatment, patients are followed up at 1 month, every 3 months for 1 year, every 6 months for the next 2 years, and then annually for 2 years.

Inclusion Criteria:

• Patients who are 18 years or older.
• Performance Status 0-2 (ECOG) at time of consult with radiation oncology.
• Pathologically proven non-small cell lung cancer (NSCLC) with evidence of metastatic disease.
• Must have received 4 cycles of standard of care systemic therapy (usually this will consist of combination chemo-immunotherapy), with a CT chest abdomen pelvis that was performed after completion of these 4 cycles and demonstrates no evidence of progression per RECIST v1.1.
• To be eligible for enrollment and randomization, patients must be within 180 days from their first dose of standard of care systemic therapy. Cycle 1 day 1 is defined as day 1. If enrolled on day 180, the patient would need to be randomized the same day.
• Persistent active disease must be amenable to radiation treatment per the treating radiation oncologist, and patients must have at least one residual site of disease which can be identified by CT or PET/CT and targeted with radiation.
• Patients who previously had earlier stage NSCLC treated definitively and have now developed new distant disease, are eligible for inclusion if they have undergone at least 4 cycles of standard of care systemic therapy for their metastatic recurrence, and they meet all criteria above.
• There are no strict size or tumor number limitations in a given organ (lung, liver, abdomen pelvis, or spine). This is at the discretion of the treating radiation oncologist.

Exclusion Criteria from Enrollment

• More than 180 days has elapsed since day 1 of cycle 1 of standard of care systemic therapy.
• Pregnant or lactating women.
• The patient has received treatment for other carcinomas within the last three years (Except for cured non-melanoma skin cancer, low-risk prostate cancer, T1/T2 glottic cancer, stage 0 or stage I breast cancer, non-invasive bladder cancer, or treated in-situ cervical cancer). Prior lung cancer diagnosis now with oligometastatic recurrence is not an exclusion criteria.
• Patients with major activating mutations in EGFR (del19, L858R, and T790M) or ROS 1 or ALK gene rearrangements are excluded

Eligibility for Randomization

• Once enrolled on study, patients will have a PET/MRI brain for restaging. Patients with no evidence of progression and 8 or fewer sites of active persistent disease per the treating physician are eligible for randomization.
• If a PET has been performed within 30 days of enrollment with no evidence of progression per RECIST v1.1, then this scan may be used and does not have to be repeated prior to randomization.
• If an MRI brain has been performed within 90 days of enrollment with no evidence of progression per RECIST v1.1, then this scan may be used and does not have to be repeated prior to randomization.

Up to 5 years

This study enrolled n=5 patients. Four of 5 were randomized to arm 1, and the remaining patient was randomized to arm 2.

Only one patient (arm 1) had any primary/secondary outcomes--1 patient in arm 1 had progression to a new disease site and died soon thereafter.

Due to these small numbers statistical analysis (e.g., rates, statistical comparisons of arms) are not possible.

Descriptive and count data have thus been entered into the outcomes data fields.