Five-year overall survival with ipilimumab and stereotactic ablative radiotherapy for metastatic disease.

PURPOSE: Ipilimumab plus stereotactic ablative radiotherapy (SABR) demonstrate satisfactory short-term clinical benefit and low toxicities in metastatic cancers. Here, we report the 5-year overall survival (OS) rates for patients with metastatic disease treated with this combined-modality therapy in a phase II trial (NCT02239900). METHODS AND MATERIALS: SABR was delivered to patients with metastatic lesions in the liver and lung either during the first dose (concurrent) or 1 week after the second dose (sequential) of ipilimumab (every 3 weeks for 4 cycles). SABR was administered to liver or lung metastases as 50 Gy in 4 fractions or 60 Gy in 10 fractions, considering the tumor location. The OS rates at 12, 36, and 60 months were estimated by the Kaplan-Meier method; subgroup analyses of progression-free survival (PFS) and OS by SABR-targeted lesions (liver/lung) were performed by log-rank tests. RESULTS: A total of 106 patients were enrolled in this long-term follow-up analysis. At the median follow-up time of 15.32 months (range, 0.97-82.13 months), the median PFS was 6.52 months (95% CI, 5.86-7.14) and the median OS was 15.32 months (95% CI,13.03-17.23). The 12-, 36-, and 60-month OS rates were 61%, 23%, and 15%, respectively. There was a significant difference in OS between cohorts (P = 0.039), with a stronger response observed in lung-treated subgroups. Patients who had received sequential fractions (50 Gy/4f) to the lung had improved OS compared to those who had received sequential fractions (18.29 vs 8.9 months, P = 0.043) to the liver. Subgroup analysis of SABR-targeted lesions showed that lung-targeted groups had significantly longer PFS (6.87 months vs. 5.63 months, P = 0.034) and OS (18.67 months vs. 13.63 months, P = 0.013) compared to liver-targeted groups. The sequence did not affect the outcomes of PFS and OS. Exploratory analyses showed that SABR-targeted lesions and smoking history comprised an independent risk factor for OS. CONCLUSIONS: Updated 5-year OS data from the phase II trial demonstrate the long-term clinical benefit of ipilimumab and SABR, which warrants further research and cumulative data.

High-dose irradiation in combination with non-ablative low-dose radiation to treat metastatic disease after progression on immunotherapy: Results of a phase II trial.

AIM: To report early findings from a phase II trial of high-dose radiotherapy (HD-RT) with or without low-dose RT (LD-RT) for metastatic cancer. METHODS: Eligible patients had metastatic disease that progressed on immunotherapy within 6 months. Patients were given either HD-RT (20-70 Gy total; 3-12.5 Gy/f), or HD-RT + LD-RT (0.5-2 Gy/f up to 1-10 Gy total) to separate lesions, with continued immunotherapy. Radiographic response was assessed per RECIST 1.1 and Immune-Related Response Criteria (irRC). Primary endpoints: (1) 4-month disease control (DCR, complete/partial response [CR/PR] or stable disease [SD]) or an overall response (ORR, CR/PR) at any point in ≥10% of patients, per RECIST 1.1; (2) dose-limiting toxicity within 3 months not exceeding 30%. Secondary endpoint was lesion-specific response. RESULTS: Seventy-four patients (NSCLC, n = 38; melanoma n = 21) were analyzed (39 HD-RT and 35 HD-RT + LD-RT). The median follow-up time was 13.6 months. The primary endpoint was met for 72 evaluable patients, with a 4-month DCR of 42% (47% [16/34] vs. 37% [14/38] in HD-RT + LD-RT vs. HD-RT, P = 0.38), and 19% ORR at any time (26% [9/34] vs. 13% [5/38] in HD-RT + LD-RT vs. HD-RT, P = 0.27). Three patients had toxicity ≥grade 3. LD-RT lesion response (53%) was improved compared to nonirradiated lesions in HD-RT + LD-RT (23%, P = 0.002) and HD-RT (11%, P < 0.001). T- and NK cell infiltration was enhanced in lesions treated with LD-RT. CONCLUSIONS: HD-RT plus LD-RT safely improved lesion-specific response in patients with immune resistant solid tumors by promoting infiltration of effector immune cells into the tumor microenvironment.

Considerations for Clinical Trials Testing Radiotherapy Combined With Immunotherapy for Metastatic Disease.

Metastatic cancer is inherently heterogeneous, and patients with metastatic disease can experience vastly different oncologic outcomes depending on several patient- and disease-specific characteristics. Designing trials for such a diverse population is challenging yet necessary to improve treatment outcomes for metastatic-previously thought to be incurable-disease. Here we review core considerations for designing and conducting clinical trials involving radiation therapy and immunotherapy for patients with metastatic cancer.

Pembrolizumab with or without radiotherapy for metastatic non-small-cell lung cancer: a pooled analysis of two randomised trials.

BACKGROUND: Radiotherapy might augment systemic antitumoral responses to immunotherapy. In the PEMBRO-RT (phase 2) and MDACC (phase 1/2) trials, patients with metastatic non-small-cell lung cancer were randomly allocated immunotherapy (pembrolizumab) with or without radiotherapy. When the trials were analysed individually, a potential benefit was noted in the combination treatment arm. However, owing to the small sample size of each trial, differences in response rates and outcomes were not statistically significant but remained clinically notable. We therefore did a pooled analysis to infer whether radiotherapy improves responses to immunotherapy in patients with metastatic non-small-cell lung cancer. METHODS: Inclusion criteria for the PEMBRO-RT and MDACC trials were patients (aged ≥18 years) with metastatic non-small-cell lung cancer and at least one unirradiated lesion to monitor for out-of-field response. In the PEMBRO-RT trial, patients had previously received chemotherapy, whereas in the MDACC trial, patients could be either previously treated or newly diagnosed. Patients in both trials were immunotherapy-naive. In the PEMBRO-RT trial, patients were randomly assigned (1:1) and stratified by smoking status (<10 vs ≥10 pack-years). In the MDACC trial, patients were entered into one of two cohorts based on radiotherapy schedule feasibility and randomly assigned (1:1). Because of the nature of the intervention in the combination treatment arm, blinding to radiotherapy was not feasible in either trial. Pembrolizumab was administered intravenously (200 mg every 3 weeks) with or without radiotherapy in both trials. In the PEMBRO-RT trial, the first dose of pembrolizumab was given sequentially less than 1 week after the last dose of radiotherapy (24 Gy in three fractions), whereas in the MDACC trial, pembrolizumab was given concurrently with the first dose of radiotherapy (50 Gy in four fractions or 45 Gy in 15 fractions). Only unirradiated lesions were measured for response. The endpoints for this pooled analysis were best out-of-field (abscopal) response rate (ARR), best abscopal disease control rate (ACR), ARR at 12 weeks, ACR at 12 weeks, progression-free survival, and overall survival. The intention-to-treat populations from both trials were included in analyses. The PEMBRO-RT trial (NCT02492568) and the MDACC trial (NCT02444741) are registered with ClinicalTrials.gov. FINDINGS: Overall, 148 patients were included in the pooled analysis, 76 of whom had been assigned pembrolizumab and 72 who had been assigned pembrolizumab plus radiotherapy. Median follow-up for all patients was 33 months (IQR 32·4-33·6). 124 (84%) of 148 patients had non-squamous histological features and 111 (75%) had previously received chemotherapy. Baseline variables did not differ between treatment groups, including PD-L1 status and metastatic disease volume. The most frequently irradiated sites were lung metastases (28 of 72 [39%]), intrathoracic lymph nodes (15 of 72 [21%]), and lung primary disease (12 of 72 [17%]). Best ARR was 19·7% (15 of 76) with pembrolizumab versus 41·7% (30 of 72) with pembrolizumab plus radiotherapy (odds ratio [OR] 2·96, 95% CI 1·42-6·20; p=0·0039), and best ACR was 43·4% (33 of 76) with pembrolizumab versus 65·3% (47 of 72) with pembrolizumab plus radiotherapy (2·51, 1·28-4·91; p=0·0071). Median progression-free survival was 4·4 months (IQR 2·9-5·9) with pembrolizumab alone versus 9·0 months (6·8-11·2) with pembrolizumab plus radiotherapy (hazard ratio [HR] 0·67, 95% CI 0·45-0·99; p=0·045), and median overall survival was 8·7 months (6·4-11·0) with pembrolizumab versus 19·2 months (14·6-23·8) with pembrolizumab plus radiotherapy (0·67, 0·54-0·84; p=0·0004). No new safety concerns were noted in the pooled analysis. INTERPRETATION: Adding radiotherapy to pembrolizumab immunotherapy significantly increased responses and outcomes in patients with metastatic non-small-cell lung cancer. These results warrant validation in a randomised phase 3 trial. FUNDING: Merck Sharp & Dohme.

Low-dose radiation treatment enhances systemic antitumor immune responses by overcoming the inhibitory stroma.

BACKGROUND: Despite some successes with checkpoint inhibitors for treating cancer, most patients remain refractory to treatment, possibly due to the inhibitory nature of the tumor stroma that impedes the function and entry of effector cells. We devised a new technique of combining immunotherapy with radiotherapy (XRT), more specifically low-dose XRT, to overcome the stroma and maximize systemic outcomes. METHODS: We bilaterally established 344SQ lung adenocarcinoma tumors in 129Sv/Ev mice. Primary and secondary tumors were irradiated with either high-dose or low-dose of XRT with systemic anti-programmed cell death protein 1 and anti-cytotoxic T-lymphocyte associated protein 4 administration. Survival and tumor growth were monitored for the various groups, and secondary tumors were phenotyped by flow cytometry for immune populations. Tumor growth factor-beta (TGF-ß) cytokine levels were assessed locally after low-dose XRT, and specific immune-cell depletion experiments were conducted to identify the major contributors to the observed systemic antitumor effect. RESULTS: Through our preclinical and clinical studies, we observed that when tumor burden was high, there was a necessity of combining high-dose XRT to 'prime' T cells at the primary tumor site, with low-dose XRT directed to secondary (metastatic) tumors to 'modulate the stroma'. Low-dose XRT improved the antitumor outcomes of checkpoint inhibitors by favoring M1 macrophage polarization, enhancing natural killer (NK) cell infiltration, and reducing TGF-ß levels. Depletion of CD4+ T cells and NK cells abrogated the observed antitumor effect. CONCLUSION: Our data extend the benefits of low-dose XRT to reprogram the tumor environment and improve the infiltration and function of effector immune cells into secondary tumors.

Pembrolizumab with or without radiation therapy for metastatic non-small cell lung cancer: a randomized phase I/II trial.

BACKGROUND: In this phase I/II trial, we evaluated the safety and effectiveness of pembrolizumab, with or without concurrent radiotherapy (RT), for lung and liver lesions from metastatic non-small cell lung cancer (mNSCLC). METHODS: Patients with lung or liver lesions amenable to RT plus at least one additional non-contiguous lesion were included regardless of programmed death-ligand 1 (PD-L1) status. Pembrolizumab was given at 200 mg every 3 weeks for up to 32 cycles with or without concurrent RT. Metastatic lesions were treated with stereotactic body RT (SBRT; 50 Gy in 4 fractions) if clinically feasible or with traditionally fractionated RT (45 Gy in 15 fractions) if not. The primary end point was the best out-of-field lesion response, and a key secondary end point was progression-free survival (PFS). RESULTS: The median follow-up time was 20.4 months. One hundred patients (20 phase I, 80 phase II) were evaluable for toxicity, and 72 phase II patients were evaluable for treatment response. No patients in the phase I group experienced grade 4-5 events; in the phase II group, two had grade 4 events and nine had grade 3 events. The ORR in the combined-modality cohort (irrespective of RT schema) was 22%, vs 25% in the pembrolizumab group (irrespective of receipt of salvage RT) (p=0.99). In the concurrent pembrolizumab+RT groups, the out-of-field ORRs were 38% in the pembrolizumab+SBRT group and 10% in the pembrolizumab+traditional RT group. When examining the pembrolizumab-alone patients, the out-of-field ORRs were 33% in those designated to receive salvage SBRT (if required) and 17% for salvage traditional RT. In all patients, the median PFS for pembrolizumab alone was 5.1 months (95% CI 3.4 to 12.7 months), and pembrolizumab/RT (regardless of schema) was 9.1 months (95% CI 3.6 to 18.4 months) (p=0.52). An exploratory analysis revealed that for patients with low PD-L1 expression, the median PFS was 4.6 vs 20.8 months for pembrolizumab with and without RT, respectively (p=0.004). CONCLUSIONS: Concurrent immunoradiotherapy for mNSCLC is safe, although larger trials are required to address which patients benefit most from RT. TRIAL REGISTRATION NUMBER: NCT02444741.

Phase 1/2 Trial of Pembrolizumab and Concurrent Chemoradiation Therapy for Limited-Stage SCLC.

INTRODUCTION: Few advancements in treating limited-stage SCLC (LS-SCLC) have been made in decades. We report here a phase 1/2 trial of concurrent chemoradiotherapy (CRT) and pembrolizumab. METHODS: This single-center, open-label phase 1/2 study recruited adults with LS-SCLC or other neuroendocrine tumors and good performance status (Eastern Cooperative Oncology Group ≤ 2). The primary end point was safety, as assessed by dose-limiting toxicities. Concurrent CRT consisted of etoposide and a platin with 45 Gy radiotherapy (30 twice daily). Prophylactic cranial irradiation (25 Gy, 10 fractions) was given at the physician's discretion. Pembrolizumab was started concurrently with CRT and continued for up to 16 cycles. The phase 1 portion consisted of a 3 + 3 design. Toxicity was assessed with Common Terminology Criteria for Adverse Events version 4.0. Secondary outcomes were progression-free survival, overall survival, and tumor response as measured by the immune-related response criteria. RESULTS: A total of 45 patients were screened, and 40 were enrolled. All completed radiation therapy and received greater than or equal to one cycle of pembrolizumab. A total of 27 (61%) received percutaneous coronary intervention. One dose-limiting toxicity was observed in the phase 1 portion. There were no grade 5 toxicities, but there were three grade 4 events (two neutropenia, one respiratory failure). Pneumonitis rate was 15% (three grade 2 and three grade 3). All 17 esophagitis events (42.5%) were grades 1 to 2. At median follow-up time of 23.1 months, the median progression-free survival time was 19.7 months (95% confidence interval: 8.8‒30.5) and the median overall survival time was 39.5 months (95% confidence interval: 8.0‒71.0). CONCLUSION: Concurrent CRT and pembrolizumab for LS-SCLC was well tolerated and yielded favorable outcomes, providing a basis for randomized studies.