Treatment Efficacy Outcomes Combining Dual Checkpoint Immunotherapy with Ablative Radiation to All Sites of Oligometastatic Non-Small Cell Lung Cancer: Survival Analysis of a Phase IB trial

PURPOSE/OBJECTIVE(S)

Aggressivelocal treatment to a limited number of metastatic sites in patients with oligometastatic NSCLC increases progression free survival (PFS) and overall survival (OS). Prior studies have shown the safety of combining high dose stereotactic body radiation therapy (SBRT) with single agent anti-PD1/PD-L1 therapy. Here, we report secondary survival endpoint outcomes from a phase Ib clinical trial investigating the safety of combining ablative, high dose radiation with dual checkpoint, anti-CTLA-4 and anti-PD-L1 immunotherapy for patients with oligometastatic NSCLC.

MATERIALS/METHODS

Patients with up to 6 sites of extracranial metastatic disease were eligible for trial enrollment. All sites of disease were treated with stereotactic body radiation therapy to a dose of 30 - 50 Gy in 5 fractions. Dual checkpoint immunotherapy was started 7 days following completion of radiation utilizing anti-CTLA-4 (Tremelimumab) and anti-PD-L1 (Durvalumab) immunotherapy for a total of four cycles followed by durvalumab alone until dose limiting toxicity or progression was observed. Primary toxicity outcomes were previously reported. Progression free and overall survival was analyzed using Kaplan Meier statistical methods.

RESULTS

Fifteen patients were treated with SBRT and received at least one dose of dual agent immunotherapy per protocol. The median follow up was 43 months. The median number of extracranial metastatic sites was 2. Seven patients had 3 or more sites of extracranial disease. The most commonly treated sites were separate metastatic pulmonary lesions or osseous metastatic lesions. Median progression free survival (PFS) was 42 months and median overall survival (OS) was 48 months. Seven patients remain alive without evidence of progressive disease. Prior history of brain metastases was associated with significantly worse PFS (Median PFS 4 months vs 42 months, HR 6.1 (95% CI 1.6 - 37.0) p = 0.0248), but no difference in OS (Median OS 24 vs 42 months, HR 1.9 (95% CI 0.3 - 10.4).

CONCLUSION

Ablative SBRT radiation to up to 6 sites of disease followed by dual checkpoint immunotherapy in oligometastatic NSCLC resulted in a favorable progression free survival (42 months) and overall survival (48 months) compared to historical controls. These findings suggest potential benefit to patient outcomes compared to immunotherapy or radiation alone in this patient population and warrant further investigation.

Leveraging Quantitative Imaging and Machine Learning to Differentiate Radionecrosis from Disease Recurrence in Patients with Brain Metastases

PURPOSE/OBJECTIVE(S)

Radiation necrosis can be difficult to non-invasively discern from tumor progression after stereotactic radiosurgery (SRS). In this work, we investigate the utility of radiomics (computerized features) and machine learning to capture per-voxel lesion heterogeneity on routine MRI scans, to differentiate radionecrosis from tumor recurrence in patients with brain metastases treated with SRS.

MATERIALS/METHODS

A retrospective analysis was conducted of patients with brain metastases treated with SRS. Eighty-three lesions (n = 56 intact; n = 27 surgical cavity) from 69 patients were identified with median age 68.8 years (range 40.2 - 91.0), of whom 53.6% were male and 33.3% received prior whole-brain radiotherapy (WBRT). Lesion histology included lung (60.2%), renal cell (15.7%), melanoma (10.8%), breast (9.6%), and other (3.6%). Pathologic confirmation was available in 73.5% of lesions. Both intact and resection cavity lesions were included and individually segmented. Image preprocessing and radiomic feature extraction were done using ANTsPy and open-source software. A total of 210 features were extracted from post-contrast T1-weighted (T1w) and T2/FLAIR MRIs. Highly correlated features were removed. Univariate logistic regression was conducted on the remaining T1w and T2/FLAIR features as well as on clinical variables. Multivariate analysis was implemented with various classifiers (Random Forest, Ridge, Lasso, Support Vector Machine [SVM]) on the top-performing features found on univariate logistic regression. Models were assessed using cross-validation to select the best model by area under ROC curve (AUC). Specificity and sensitivity were calculated.

RESULTS

On univariate analysis, the top 10 radiomics features consisted of 6 T1w features and 4 T2/FLAIR features (4 GLCM, 3 first order, 1 GLSZM, 1 GLRLM, and 1 shape feature). Age, gender, disease site, prior WBRT, prior fractionated SRS, planning tumor volume, brain-GTV V12 Gy, and immunotherapy before or after SRS were not predictive (AUC less than 62.0%) on univariate analysis compared to radiomic features. Multivariate analysis of top performing radiomic features on both intact and surgical cavities yielded an AUC of 72.0% (standard deviation [SD] ±8.8%). Multivariate analysis of top features on intact lesions alone improved the AUC to 80.5% (SD ±10.8%), with sensitivity of 77.8%, specificity of 72.4%, and positive likelihood ratio of 2.82 in differentiating radionecrosis from recurrence.

CONCLUSION

Radiomics and machine learning tools may improve diagnostic ability of distinguishing radiation necrosis from tumor recurrence after SRS. Further work is needed to deploy this in a larger multi-institutional cohort and prospectively evaluate its efficacy as a decision-support tool to personalize care in patients with brain metastases.

Initial Results of a Phase II Trial of Hypofractionated Radiation Therapy for Inoperable Soft Tissue Sarcoma

PURPOSE/OBJECTIVE(S)

For patients with soft tissue sarcoma (STS) who cannot or choose not to have surgery, radiation can provide local tumor control in both palliative and definitive settings. Conventionally fractionated radiation provides modest (< 50%) rates of local control (LC) for STS at 2 years. To our knowledge, no prospective studies to date have evaluated the safety and efficacy of dose-escalated hypofractionated radiation therapy as treatment of inoperable STS. We hypothesized that dose-escalated, hypofractionated radiation therapy (RT) for inoperable STS could achieve higher rates of LC than reported in trials of conventionally fractionated RT.

MATERIALS/METHODS

An IRB-approved single institution prospective phase II clinical trial of dose-escalated, hypofractionated RT as local control for STS was designed and completed planned accrual. Exclusion criteria included anti-cancer systemic therapy within the preceding two weeks. Patients underwent hypofractionated RT utilizing either CT-guided radiation (24, 50%) or MRI-guided radiation treatments (24, 50%). Data on patient characteristics, RT dose and fractionation, LC, toxicity, and overall survival (OS) was collected. The primary endpoint was local tumor control (stable, partial, or complete response according to RECIST) at 2-years after completion of radiation. Secondary endpoints were acute and late toxicity, rates of complete response, 5-year local tumor control, and progression-free and overall survival. Acute toxicity was graded on the Common Terminology Criteria for Adverse Events (CTCAE) v5.0 scale during treatment and at 3 months following RT.

RESULTS

Forty-eight patients were enrolled, 17 with non-metastatic localized disease and 31 with metastatic disease. Median patient age was 64. Twenty-five men and 23 women were treated. Ninety-six total lesions were treated (36 lung, 7 extremity, 37 abdominopelvic, 16 other). Radiation dose per fraction ranged from 6-12 Gy for a total of 1-12 fractions (median dose was 52.5 Gy in 6 fractions. Median patient follow-up is 8.6 months (range 1 - 36 months). Six patients (13%) did not complete initial 3-month follow-up imaging. Of the 40 patients who have undergone 3-month follow up imaging, 32 (80%) had stable disease, 5 (12.5%) had partial response, 0 had complete response, and 3 (7.5%) had disease progression. Median PFS was 17.2 months at time of last follow up. Median OS was 12.9 months at time of last follow up. Twenty-five patients (52%) experienced an acute toxicity likely or possibly related to radiation. Three (6%) patients experienced CTACE grade 3 or greater treatment-related toxicity (pain, weakness, decreased range of motion, dermatitis).

CONCLUSION

In this initial report of a prospective, single-institution clinical trial of hypofractionated RT for STS not undergoing resection, we report low rates of acute grade 3 or greater toxicity and high rates of tumor response. We will continue to follow these patients to assess late toxicity and durability of tumor control.

Longitudinal Radiomics-Based Prediction of Local Recurrence after Stereotactic Body Radiation Therapy for Early-Stage Non-Small Cell Lung Cancer

PURPOSE/OBJECTIVE(S)

Computed tomography (CT)-based radiomic analysis is an emerging tool that can help predict recurrence after radiation in non-small cell lung cancer (NSCLC). Most studies have focused on using radiomic features obtained from pre-treatment CT scans but not on post-treatment CTs. Our goal was to determine if radiomic features derived from post-treatment CTs perform better than those from pre-treatment CTs in predicting local recurrence after stereotactic body radiation therapy (SBRT) in patients with early-stage NSCLC.

MATERIALS/METHODS

Patients with T1/T2 N0 early-stage NSCLC were retrospectively reviewed. Criteria for selection included patients with biopsy-proven NSCLC, non-ground glass solid lesions, 4-5 fraction SBRT treatments, and non-contrast thin-slice CTs available at pre-treatment baseline and at 3 and 6 months post-SBRT. Clinical and tumor characteristics were compared using Chi-square and Student's t-tests. CT image pre-processing was performed and 107 radiomic features were extracted using 3D Slicer and open-source software. Univariate analysis for local recurrence was determined by Cox regression with death as a competing risk. The Benjamini-Hochberg Procedure was applied to control the false discovery rate. Pearson correlation analysis was used to exclude redundant features (r > 0.8), and multivariate analysis was conducted with Random Forest on the top-performing features found on univariate logistic regression. Models were trained on a class-balanced loss to account for class imbalance. Twenty iterations of stratified 3 k-fold cross-validation were used to select the best model by the area under the receiver operating characteristic curve (AUC).

RESULTS

We identified and analyzed 86 patient tumors, including 76 non-local recurrences and 10 local recurrences (49 males, 37 females; age, median 72, range 52-91 years). No differences in age, histology, standardized uptake values on positron emission tomography scans, gross tumor volume, and radiation dose were found between patients with and without local recurrence (all p >0.05). The median time to local recurrence was 18.9 months (range 5.5-45.6 months). At the baseline, 3-month, and 6-month timepoints, 2, 10, and 10 radiomic features predicted local recurrence on Cox regression univariate analysis, respectively (all q <0.01). On multivariate analysis of top-performing radiomic features, the 3-month timepoint performed the best with a mean (±standard deviation) AUC score of 0.82 (±0.13) compared to a mean AUC of 0.73 (±0.086) at baseline and a mean AUC of 0.74 (±0.10) at 6 months.

CONCLUSION

Post-treatment radiomic features at 3 months outperformed pre-treatment radiomic features in predicting local recurrence after SBRT for NSCLC. These results suggest radiomic data from follow-up CTs may be helpful when developing radiomic models to predict local recurrence in patients with NSCLC.

Improved survival with dose-escalated radiotherapy in stage III non-small-cell lung cancer: analysis of the National Cancer Database

BACKGROUND

Concurrent chemoradiation is the standard of care in non-operable stage III non-small-cell lung cancer (NSCLC). Data have suggested a benefit of dose escalation; however, results from the randomized dose-escalation trial RTOG 0617 revealed a lower survival rate with high-dose radiation. To evaluate the impact of dose escalation on overall survival (OS) in stage III NSCLC treated with chemoradiotherapy outside the controlled setting of a randomized trial, we carried out an observational, population-based investigation of the National Cancer Database (NCDB).

PATIENTS AND METHODS

A total of 33 566 patients with stage III NSCLC treated with chemoradiation from 2004 to 2012 and radiation doses between 59.4 and 85 Gy were included. The primary end point was OS, with median survival calculated via Kaplan-Meier. Univariate, multivariable and propensity-score matching analyses were carried out.

RESULTS

Patients were stratified by dose with median OS of: 18.8, 19.8 and 21.6 months for cohorts receiving 59.4-60, 61-69 and ≥70 Gy, respectively (P < 0.001). Granular dose analyses were carried out demonstrating increased OS with increasing radiation dose: median survival of 18.8, 21.1, 22.0 and 21.0 months for 59.4-60, 66, 70 and ≥71 Gy, respectively. While 66, 70 and ≥71 Gy resulted in increased OS in comparison with 59.4-60 Gy, no significant difference in OS was observed when comparing 66 with ≥71 Gy (P = 0.38).

CONCLUSIONS

Dose escalation above 60 Gy was associated with improved OS in this cohort of stage III NSCLC patients treated with chemoradiotherapy. A plateau of benefit was observed, with no additional improvement in OS with increased dose (≥71 Gy) compared with 66-70 Gy. With evidence suggesting worse OS and quality of life with increased dose, these data support investigation of the role of intermediate-dose radiation, and in the absence of randomized evidence, may be leveraged to justify utilization of intermediate-dose radiation.

Lung metastases treated with image-guided stereotactic body radiation therapy

AIMS

To evaluate outcomes after treatment with image-guided stereotactic body radiation therapy (SBRT) using daily online cone beam computed tomography for malignancies metastatic to the lung.

MATERIALS AND METHODS

Forty-seven lung metastases in 32 patients were treated with volumetrically guided SBRT. The median age was 62 years (21-87). Primaries included colorectal (n = 10), sarcoma (n = 4), head and neck (n = 4), melanoma (n = 3), bladder (n = 2), non-small cell lung cancer (n = 2), renal cell (n = 2), thymoma (n = 2), thyroid (n = 1), endometrial (n = 1) and oesophageal (n = 1). The number of lung metastases per patient ranged from one to three (68% single lesions). SBRT was prescribed to the edge of the target volume to a median dose of 60 Gy (48-65 Gy) in a median of four fractions (four to 10). Most lesions were treated using 12 Gy fractions (92%) to 48 or 60 Gy.

RESULTS

The median follow-up was 27.6 months (7.6-57.1 months). The 1, 2 and 3 year actuarial local control rates for all treated lesions were 97, 92 and 85%, respectively. Two patients with colorectal primaries (four lesions in total) had local failure. The median overall survival was 40 months. The 1, 2 and 3 year overall survival from the time of SBRT completion was 83, 76 and 63%, respectively. There were no grade 4 or 5 toxicities. Grade 3 toxicities (one instance of each) included pneumonitis, dyspnoea, cough, rib fracture and pain.

CONCLUSION

SBRT with daily online cone beam computed tomography for lung metastases achieved excellent local tumour control with low toxicity and encouraging 2 and 3 year survival.