Patterns of Failure, Low-Volume Relapse, and Subsequent Ablative Management in Locally Advanced Non-Small Cell Lung Cancer Treated With Definitive Chemoradiation and Consolidation Immune Checkpoint Inhibitors.

PURPOSE: The objective of this study was to describe the patterns of failure, frequency of low-volume relapse (LVR), and candidacy for ablative therapy at time of disease progression (PD) after chemoradiation and consolidative immunotherapy (CRT + ICI) in patients with stage III non-small cell lung cancer. METHODS AND MATERIALS: We identified 229 consecutive patients with stage III non-small cell lung cancer treated with CRT + ICI between October 2017 and December 2021 at a single institution. PD was classified as isolated locoregional failure (LRF), isolated distant failure (DF), or synchronous LRF + DF. Any LRF was subclassified as in-field failure, marginal failure, or out-of-field failure. LVR was defined as 3 or fewer sites of PD in any number of organs. Ablative candidates were defined as having 5 or fewer sites of PD radiographically amenable to high-dose radiation or surgery. Time-to-event data were calculated using cumulative incidence analysis and Kaplan-Meier methods. Multivariable Cox modeling was used to examine the correlations between characteristics of relapse and postprogression survival. RESULTS: Of the 229 patients, 119 (52%) had PD. Of these 119 patients, 20 (21%) had isolated LRF, 28 (24%) had synchronous LRF + DF, and 71 (60%) had isolated DF. Of the 48 patients with any LRF, 28 (58%) had in-field failure, 10 (21%) marginal failure, and 10 (21%) out-of-field failure. The cumulative incidence of LRF and DF was 13% (95% CI, 9.2%-18%) and 32% (95% CI, 26%-38%) at 1 year and 19% (95% CI, 14%-24%) and 39% (95% CI, 33%-46%) at 2 years, respectively. Overall, 64 patients (54%) were considered to have LVR. At time of PD, 60 patients (50%) were eligible for ablative therapy. Patients with LVR had longer median survival versus with high-volume relapse (37.4 vs 15.2 months, P < .001). On multivariable analysis, LVR (hazard ratio, 0.32; 95% CI, 0.18-0.56; P < .001) was associated with improved postprogression survival. CONCLUSIONS: After CRT + ICI, approximately half of patients experience LVR at time of PD and are candidates for ablative therapies. Prospective trials are needed to validate the optimal treatment strategy for LVR.

The effective radiation dose to immune cells predicts lymphopenia and inferior cancer control in locally advanced NSCLC.

PURPOSE: To explore the association of the effective dose to immune cells (EDIC) with disease control, lymphopenia, and toxicity in patients with non-small cell lung cancer (NSCLC) and identify methods to reduce EDIC. METHODS: We abstracted data from all patients with locally advanced NSCLC treated with chemoradiation with or without consolidative immunotherapy over a ten-year period. Associations between EDIC and progression-free survival (PFS) and overall survival (OS) were modeled with Cox proportional hazards and Kaplan-Meier method. Logistic regression was used to model predictors of lymphopenia and higher EDIC. Analyses were performed with EDIC as a continuous and categorical variable. Lymphopenia was graded per CTCAE v5.0. RESULTS: Overall, 786 patients were included (228 of which received consolidative immunotherapy); median EDIC was 4.7 Gy. Patients with EDIC < 4.7 Gy had a longer median PFS (15.3 vs. 9.0 months; p < 0.001) and OS (34.2 vs. 22.4 months; p < 0.001). On multivariable modeling, EDIC correlated with inferior PFS (HR 1.08, 95 % CI 1.01-1.14, p = 0.014) and OS (HR 1.10, 95 % CI 1.04-1.18, p = 0.002). EDIC was predictive of grade 4 lymphopenia (OR 1.16, 95 % CI 1.02-1.33, p = 0.026). EDIC ≥ 4.7 Gy was associated with increased grade 2 + pneumonitis (6-month incidence: 26 % vs 20 %, p = 0.04) and unplanned hospitalizations (90-day incidence: 40 % vs 30 %, p = 0.002). Compared to protons, photon therapy was associated with EDIC ≥ 4.7 Gy (OR 5.26, 95 % CI 3.71-7.69, p < 0.001) in multivariable modeling. CONCLUSIONS: EDIC is associated with inferior disease outcomes, treatment-related toxicity, and the development of severe lymphopenia. Proton therapy is associated with lower EDIC. Further investigations to limit radiation dose to the immune system appear warranted.

Death without progression as an endpoint to describe cardiac radiation effects in locally advanced non-small cell lung cancer.

Background and purpose: Prior studies have examined associations of cardiovascular substructure dose with overall survival (OS) or cardiac events after chemoradiotherapy (CRT) for non-small cell lung cancer (NSCLC). Herein, we investigate an alternative endpoint, death without cancer progression (DWP), which is potentially more specific than OS and more sensitive than cardiac events for understanding CRT toxicity. Materials and methods: We retrospectively reviewed records of 187 patients with locally advanced or oligometastatic NSCLC treated with definitive CRT from 2008 to 2016 at a single institution. Dosimetric parameters to the heart, lung, and ten cardiovascular substructures were extracted. Charlson Comorbidity Index (CCI), excluding NSCLC diagnosis, was used to stratify patients into CCI low (0-2; n = 66), CCI intermediate (3-4; n = 78), and CCI high (≥5; n = 43) groups. Primary endpoint was DWP, modeled with competing risk regression. Secondary endpoints included OS. An external cohort consisted of 140 patients from another institution. Results: Median follow-up was 7.3 years for survivors. Death occurred in 143 patients (76.5 %), including death after progression in 118 (63.1 %) and DWP in 25 (13.4 %). On multivariable analysis, increasing CCI stratum and mean heart dose were associated with DWP. For mean heart dose ≥ 10 Gy vs < 10 Gy, DWP was higher (5-year rate, 16.9 % vs 6.7 %, p = 0.04) and OS worse (median, 22.9 vs 34.1 months, p < 0.001). Ventricle (left, right, and bilateral) and pericardial but not atrial substructure dose were associated with DWP, whereas all three were inversely associated with OS. Cutpoint analysis identified right ventricle mean dose ≥ 5.5 Gy as a predictor of DWP. In the external cohort, we confirmed an association of ventricle, but not atrial, dose with DWP. Conclusion: Cardiovascular substructure dose showed distinct associations with DWP. Future cardiotoxicity studies in NSCLC could consider DWP as an endpoint.

Quiescent fibroblasts are protected from proteasome inhibition-mediated toxicity.

Proteasome inhibition is used as a treatment strategy for multiple types of cancers. Although proteasome inhibition can induce apoptotic cell death in actively proliferating cells, it is less effective in quiescent cells. In this study, we used primary human fibroblasts as a model system to explore the link between the proliferative state of a cell and proteasome inhibition-mediated cell death. We found that proliferating and quiescent fibroblasts have strikingly different responses to MG132, a proteasome inhibitor; proliferating cells rapidly apoptosed, whereas quiescent cells maintained viability. Moreover, MG132 treatment of proliferating fibroblasts led to increased superoxide anion levels, juxtanuclear accumulation of ubiquitin- and p62/SQSTM1-positive protein aggregates, and apoptotic cell death, whereas MG132-treated quiescent cells displayed fewer juxtanuclear protein aggregates, less apoptosis, and higher levels of mitochondrial superoxide dismutase. In both cell states, reducing reactive oxygen species with N-acetylcysteine lessened protein aggregation and decreased apoptosis, suggesting that protein aggregation promotes apoptosis. In contrast, increasing cellular superoxide levels with 2-methoxyestradiol treatment or inhibition of autophagy/lysosomal pathways with bafilomycin A1 sensitized serum-starved quiescent cells to MG132-induced apoptosis. Thus, antioxidant defenses and the autophagy/lysosomal pathway protect serum-starved quiescent fibroblasts from proteasome inhibition-induced cytotoxicity.