Investigating real-world treatment sequencing outcomes in advanced pancreatic cancer: A purple translational registry analysis.
Authors: Santucci Jordan , Lee Belinda , Mendis Shehara Ramyalini , Thomson Benjamin N , Michael Michael , Shapiro Julia , Wong Rachel , Clarke Kate , Pattison Sharon Tracy , Burge Matthew E. , Zielinski Robert Richard , Nikfarjam Mehrdad , Ananda Sumitra , Lipton Lara Rachel , Gibbs Peter 
Published: January 2021

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Background: Current standard combination first line palliative chemotherapy regimens in advanced pancreatic ductal adenocarcinoma (PDAC) have not been compared in head-to-head trials. Data on optimum treatment sequencing is also lacking. Methods: To assess whether first line (1L) treatment with gemcitabine/nab-paclitaxel (Gem/Nab-P)(SEQ1) or FOLFIRINOX (SEQ2) in the palliative treatment setting impacts survival outcomes, data for patients receiving palliative intent combination chemotherapy between 2016 and May 2020 was extracted from PURPLE, a prospective pancreatic cancer registry enrolling consecutive patients across multiple institutions. Results: Of 637 patients, 180 (28%) who received 1L single agent therapy and/or palliative radiotherapy were excluded. Of the remaining 449 patients, 132 (29%) had locally advanced disease (LA PDAC), 67 had local recurrence (15%), and 250 (56%) had de novo metastatic disease (mPDAC). Patients receiving 1L Gem/Nab-P (n=376, 84%) were older (median 67 vs 59 years, P<0.001), had a higher Charlson Comorbidity Index (CCI) (CCI ≥2: 18% vs 3%, Odds Ratio [OR] 8.0, P=0.002), and poorer performance status (ECOG≥2: 10% vs 1%, OR 8.4, P=0.01) compared to the 1L FOLFIRINOX group (n=73, 16%). 140 (37%) patients receiving 1L Gem/Nab-P (SEQ1) and 32 (44%) patients receiving 1L FOLFIRINOX (SEQ2) received second line (2L) chemotherapy. SEQ1 2L regimens included FOLFIRINOX (n=14), FOLFIRI (n=49), FOLFOX (n=35) and 5FU alone (n=3). SEQ2 2L regimens included Gem/Nab-P (n=19), Gem/5FU (n=4), Gem/Cisplatin (n=1) and gemcitabine alone (n=5). Median progression free survival (mPFS) did not differ between patients receiving 1L Gem/Nab-P vs 1L FOLFIRINOX (5.7 vs 5.1 months, P=0.54); nor did median overall survival (mOS; 11.3 vs 12.3 months, P=0.37). In the subset of patients who went on to receive 2L chemotherapy, mPFS in 2L was shorter for SEQ1 compared to SEQ2 (2.9 vs 5.2 months, Hazard Ratio [HR] 1.3, P=0.03) but mOS did not differ (15.9 vs 17.3 months P=0.91). In the subset with LA PDAC, mPFS in 2L was comparable (2.9 vs 3.3 months, P=0.55) but mOS was significantly longer with SEQ1 (22.5 vs 13.8 months, HR 0.50, P=0.01). In mPDAC, mPFS in 2L was shorter with SEQ1 (2.3 vs 5.6 months, HR 1.64, P=0.03), but mOS did not differ by sequence (13 vs 17 months, P=0.23). Conclusions: There were no significant differences in survival outcomes between 1L choices of chemotherapy, despite patients offered 1L FOLFIRINOX (SEQ2) being younger and fitter. Survival differences observed for LA PDAC versus mPDAC will be further explored. Given the multiple potential confounders, randomised clinical trials are needed to make firmer conclusions regarding the optimal initial treatment for each patient subset.