Abstract B36: Maintenance chemotherapy after chemoradiation in patients with locally advanced pancreatic cancer
Authors: Mizrahi Jonathan D. , Moningi Shalini , Nogueras-Gonzalez Graciela M. , Wolff Robert A. , Javle Milind M. , Varadhachary Gauri R. , Ho Linus , Fogelman David R. , Raghav Kanwal P. , Overman Michael J. , Crane Christopher H. , Herman Joseph M. , Koong Albert C. , Koay Eugene J. , Rogers Jane E. , Pant Shubham 
Published: March 2020

Abstract
Background: More than half of patients (pts) with pancreatic cancer (PC) initially present with unresectable, locally advanced disease (LAPC). Data on management of these pts after systemic chemotherapy are scarce. Many clinicians utilize a strategy of induction chemotherapy followed by consolidative concurrent chemoradiation (CRT) for pts not progressing on initial chemotherapy. How to manage pts after CRT is controversial. We sought to evaluate the role of maintenance chemotherapy (MCT) after CRT in pts with LAPC.
Methods: We retrospectively analyzed LAPC pts treated with CRT at MD Anderson from 2005-2018. Pts who were taken for curative-intent surgery were excluded. Primary and secondary outcomes were median progression-free survival (mPFS) and median overall survival (mOS), respectively, as measured from the start date of CRT. Data were also obtained on pt demographics, response, and duration of induction chemotherapy as well as MCT regimens.
Results: We included 165 pts with LAPC treated with CRT in our analysis. Median age was 66 (range 39 – 84), and 97 (59%) pts were male. Median follow-up was 12.9 months. The median duration from initiation of induction chemotherapy to start of CRT was 4.4 months. Most pts (84%) received 1 line of induction chemotherapy prior to CRT. Ten pts (6%) did not receive induction chemotherapy and 17 pts (10%) received at least 2 lines prior to CRT. All but 9 pts (94%) developed disease progression (PD) after CRT, and 49 pts (33%) had PD within 3 months of CRT. On univariate analysis, PD on the induction chemotherapy regimen immediately prior to CRT was associated with shortened PFS (HR 2.46, p &lt; 0.001) and OS (HR 2.96, p &lt; 0.001) after CRT. Most pts (78%) did not receive MCT after CRT. 69% of pts who received MCT were male, compared to 56% of those who did not receive MCT. The percentages of pts who had PD on the chemotherapy regimen immediately prior to CRT in the MCT and no-MCT groups were 9% and 12%, respectively. Sixteen pts who received MCT were treated with either gemcitabine alone or a gemcitabine-containing regimen, while 14 pts received capecitabine monotherapy. On univariate analysis, the use of MCT after CRT was associated with prolonged mPFS (9.0 vs. 4.2 months, p = 0.01), but was not associated with an increase in mOS (15.5 vs. 12.5 months, p = 0.14). On multivariable analysis controlling for race, radiation dose, age, and whether there was progression on the chemotherapy regimen prior to CRT, the use of MCT was significantly associated with both prolonged PFS (HR 0.45, p &lt; 0.001) and OS (HR 0.66, p = 0.047).
Conclusions: In this single-institution retrospective analysis of 165 pts with LAPC treated with CRT, treatment with post-CRT MCT was associated with a significant improvement in both PFS and OS as measured from the start date of CRT. Based on these results, MCT may be an appropriate option for pts with LAPC who have not progressed following consolidative CRT, and a prospective trial should be performed to better address this knowledge gap.
Citation Format: Jonathan D. Mizrahi, Shalini Moningi, Graciela M. Nogueras-Gonzalez, Robert A. Wolff, Milind M. Javle, Gauri R. Varadhachary, Linus Ho, David R. Fogelman, Kanwal P. Raghav, Michael J. Overman, Christopher H. Crane, Joseph M. Herman, Albert C. Koong, Eugene J. Koay, Jane E. Rogers, Shubham Pant. Maintenance chemotherapy after chemoradiation in patients with locally advanced pancreatic cancer [abstract]. In: Proceedings of the AACR Special Conference on Pancreatic Cancer: Advances in Science and Clinical Care; 2019 Sept 6-9; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2019;79(24 Suppl):Abstract nr B36.