Renouf, Daniel J.

TPS4204 Background: The role of neoadjuvant chemotherapy in resectable pancreatic cancer has yet to be defined. Recent phase II trial results demonstrate a median overall survival time (mOS) of only 22.4 months after treatment with perioperative modified FOLFIRINOX (mFOLFIRINOX) with 36% not reaching surgery due to disease progression during neoadjuvant therapy. While potential benefits and shortcomings of neoadjuvant chemotherapy have been well documented, to date, no phase III trial has directly compared a perioperative versus an adjuvant chemotherapy strategy in resectable pancreatic cancer. Alliance for Clinical Trials in Oncology A021806 is an actively accruing randomized controlled phase III trial evaluating the efficacy of perioperative chemotherapy with mFOLFIRINOX in patients with resectable pancreatic cancer. Methods: To qualify for enrollment, patients must have biopsy-proven localized resectable pancreatic adenocarcinoma as defined by the National Comprehensive Cancer Network. Patients must have good performance status (ECOG 0 or 1) and be candidates to receive mFOLFIRINOX treatment. All patients enrolled undergo central radiologic eligibility review for quality control and are then randomized to either Arm 1 which consists of 8 cycles of neoadjuvant mFOLFIRINOX followed by 4 cycles of adjuvant mFOLFIRINOX or Arm 2 which includes upfront surgery followed by 12 cycles of adjuvant mFOLFIRINOX. The primary endpoint of the trial is overall survival with secondary endpoints evaluating disease-free survival, margin-negative resection rate, surgical complications, and chemotherapeutic adverse events. Additional correlative endpoints include quality of life and radiomic imaging assessments. A total enrollment of 352 patients is planned from the US and Canada; current enrollment for this trial is at 145 patients. An OS interim analysis will be performed when 50% of the events (124) are observed combining the two arms. If the trial continues after interim analysis, the final OS analysis will be performed with a total of 248 events (combined arms). If the Cox model (stratified by tumor location and ECOG PS) comparing OS between arms produces a one-sided p-value < 0.05, then we will conclude that the OS of the perioperative therapy arm is superior to adjuvant therapy. The Alliance A021806 phase III trial aims to define a new standard of care for patients with resectable pancreatic cancer. Clinical trial information: NCT04340141 .

3579 Background: BRAFV600E ( BRAF) mutations (mts) portend poor prognosis in mCRC and patients (pts) may die before ascertainment. Since 2014, Vancouver Coastal Health (VCH) has performed reflex hereditary screening of CRCs with BRAF and mismatch repair (MMR) immunohistochemistry (IHC). We evaluated this BRAF mt population-based cohort ( BRAFPOP) to establish the true prognosis of BRAF mts in mCRC. Methods: We reviewed all mCRCs from VCH between 4/2014 and 5/2018 for BRAF by IHC (VE1 antibody). Overall survival (OS) from stage IV diagnosis was compared to mCRCs with next generation sequencing (NGS) determined BRAF mts ( BRAFNGS) from BC Cancer & MD Anderson. BRAFNGS OS did not differ by center (p = 0.77). Results: See table for BRAF cohort baseline characteristic comparison. BRAFPOP pts had worse OS than BRAFNGS pts (HR 2.5, 95% CI 1.6 – 3.9, P < 0.0001). Median OS for all BRAF mt pts was 17.9 mos. Both groups had worse OS than wild type pts (P < 0.0001). 52 (81%) of BRAFPOP pts were referred to oncology, 40 (63%) received chemotherapy, and 12 (19%) had NGS BRAF testing. BRAFPOP pts who had NGS testing with BRAF mts had OS comparable to other BRAFNGS pts (P = 0.89) and better OS than BRAFPOP pts that never had NGS testing (HR 0.37, 95% CI 0.18-0.76, P = 0.030). Pts with BRAF mts and MMR deficiency (dMMR) (n = 40) had worse OS than MMR proficiency (pMMR, n = 202) (1.6, 95% CI 1.0-2.5, P = 0.011). This was driven by BRAFPOP dMMR pts (HR 1.9, 95% CI 0.9-4.0, P = 0.036) as no difference was seen by MMR in BRAFNGS pts (HR 1.3, 95% CI 0.8-2.2, P = 0.30). Conclusions: Current estimates of prognosis for mCRC with BRAF mts likely underestimate its impact due to referral bias for NGS testing. BRAF mts with dMMR are associated with worse prognosis than pMMR. This appears driven by BRAFPOP pts. [Table: see text]