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Kamya Sankar
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P21 - Locoregional and Oligometastatic Disease - Treatment of Locally Advanced NSCLC (ID 131)
- Event: WCLC 2020
- Type: Posters
- Track: Locoregional and Oligometastatic Disease
- Presentations: 1
- Moderators:
- Coordinates: 1/28/2021, 00:00 - 00:00, ePoster Hall
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P21.09 - Does Duration of Maintenance Durvalumab Matter? Relationship between Length of Durvalumab Therapy and PFS. (ID 3197)
00:00 - 00:00 | Presenting Author(s): Kamya Sankar
- Abstract
Introduction
The standard of care for stage III non-small cell lung cancer (NSCLC) is platinum-based chemotherapy with radiotherapy (CRT) followed by maintenance with the immune checkpoint inhibitor (ICI) durvalumab, based on results of the PACIFIC trial. However, the PACIFIC trial did not include Veterans, a unique group with significant medical co-morbidities. We present a dual-institutional observational study of Veterans and civilians treated for stage III NSCLC.
Methods
We performed a retrospective review of patients (pts) with unresectable stage III NSCLC treated with CRT and ICI therapy at the VA Ann Arbor Healthcare System (VA) and the University of Michigan (UM) from January 1, 2018 to July 1, 2020. Patient data was reviewed for demographics, clinicopathological characteristics, treatment, and outcomes. Descriptive statistics was used to calculate measures of frequency and central tendency. A two-sample independent t-test was used to compare clinical characteristics between the two groups. Standard survival analysis using Kaplan-Meier method and Cox Proportional-Hazards Regression model were used to determine PFS, OS and independent predictors of PFS.
Results
We identified 43 UM and 31 VA pts who met our inclusion criteria. UM and VA pts had similar tumor histology, smoking status, and AJCC 8th edition TNM stage. The VA cohort had a higher proportion of male pts (30/31 (97.1%) vs. 16/43 (37.7%), P < 0.0001) and a higher baseline Charlson Co-Morbidity Index (CCMI) (P 0.004). 21/31 VA pts (68.6%) and 41/43 UM pts (95.5%) completed the intended course of chemotherapy (P 0.552). Veterans were more likely to have interruption of durvalumab (18/31 VA pts (58.8%) vs. 18/43 UM pts (42.2%)) and therefore received a lower average number of durvalumab treatments (5.2 vs. 11.2, P 0.0012), most commonly due to toxicity. The median PFS and OS were significantly inferior in VA pts as compared to UM pts (median PFS 21.0 vs. 24.0 months, P 0.02) (median OS not reached, 24-month OS 60.2% vs. 90.1%, HR 0.2047, P 0.02). Among those who progressed, a similar proportion of VA and UM pts received subsequent anti-cancer therapies (6/12 (50%) vs. 7/11 (63.6%), P 0.83). In a multivariate survival analysis, adenocarcinoma histology (HR 0.3, P 0.05), Stage IIIB/IIIC as compared to IIIA (HR 3.9, P 0.01), premature chemotherapy discontinuation (HR 3.3, P 0.05), and receiving fewer number of durvalumab treatments (HR 0.9, P 0.003) were factors which predicted progression in the entire population.
Conclusion
PFS and OS were shorter among Veterans with Stage III NSCLC compared with the civilian population. These groups were statistically different with regards to gender, CCMI, and ability to complete intended therapy. In multivariate survival analyses, fewer number of durvalumab treatments was the only independent factor found to be statistically different between the two groups and also contribute to inferior PFS. Veterans present a unique group of lung cancer patients. Alternative dosing regimens and schedules may need to be studied along with longer term follow up in a larger cohort to attempt to understand the disparity gap with respect to outcomes in Veterans with Stage III NSCLC.
