Citations

Key PointsCandidate SNP associations with survival outcomes after URD transplant are most likely false-positive findings. Over 85% of candidate SNPs are not linked to a biochemical function; of those that are, about half are not linked to the candidate gene.

Abstract Introduction: 5-fluorouracil (5-FU)-based chemoradiation (CRT) is a standard neoadjuvant treatment strategy for the treatment of locally-advanced rectal adenocarcinomas (LARC). MEK-1/2 inhibition has been shown to radiosensitize Ras mutant tumors in preclinical models, including colorectal cancer. In this phase 1 trial, we are testing MEK-1/2 inhibition in combination with neoadjuvant CRT for LARC. Methods: This trial is a standard 3+3 design testing 3 dose levels of the MEK-1/2 inhibitor trametinib in combination with CRT: 0.5 mg, 1.0 mg, and 2.0 mg daily, followed by an expansion cohort. All patients first receive a one week lead-in dosing of trametinib monotherapy, and undergo a tumor biopsy at the end of that week to assess pharmacodynamic inhibition by immunohistochemistry (IHC). Then, patients receive standard CRT (5-FU 225 mg/m2 per day by continuous infusion during radiotherapy, and 50.4 Gy in 28 fractions, 5 days/ week) in combination with trametinib (5 days/week). Patients have total mesorectal excision (TME) 6-10 weeks after completion of CRT. Results: 17 patients have been enrolled to date, with current enrollment occurring on the trametinib 2 mg expansion cohort (total 18 patients planned). Of these, 15 patients (10 males, 5 females) have toxicity and surgical response data available. Median age is 53 years (range 35-74 years), and 6 patients have Stage II disease, while 9 patients with Stage III disease. There have been no grade 4-5 toxicities. One dose-limiting toxicity (DLT) of diarrhea occurred in the 2mg dose cohort, attributed mainly to 5FU CRT, but led to trametinib discontinuation. Generalized skin rash led to trametinib discontinuation after 2 weeks of therapy for 1 patient and was held for 3 days for 2 patients. All patients completed TME, and 3 patients had wound infection at 2 weeks after TME, while 2 patients had perineal wound infection at 4 weeks after TME. Three out of 9 (33%) patients at the 2mg dose cohort had a pathologic complete response (pCR), and 2/9 (22%) patients had a near pCR. Adjuvant chemotherapy was given to 10 patients, 4 patients did not receive (3 refused), and 1 patient is pending. Correlative research studies have been performed in the first 12 patients enrolled. Examination of phospho-ERK levels using Vectra quantitative immunohistochemistry in pre-treatment versus post-lead-in trametinib tumor tissue reveals dose-dependent decreases in p-ERK expression in both tumor and stromal tissue as trametinib is increased from 0.5 to 2.0 mg (range 18-46% absolute reduction), with maximal reduction observed in the 2 mg cohort. Additionally, we have performed whole exome sequencing of a custom panel of 279 cancer associated genes (IGNITE platform) in tumor and normal tissue, and have identified high frequency mutations in KRAS, BRAF, and TP53, as well as additional lower frequency mutations in every tumor. One patient was noted to have microsatellite instability. Finally, we will present data correlating degree of change in p-ERK staining, mutational analysis, and mismatch repair status with pathologic response. Conclusions: The combination of trametinib with 5-FU-based CRT for LARC is feasible with promising signs of clinical activity and tolerability. Initial analysis of tumor tissue confirms dose-dependent pharmacodynamic inhibition of ERK-1/2 within 5 days of starting trametinib. Citation Format: Terence M. Williams, Christina Wu, Lai Wei, Emily Chan, Ryan Robb, Sameek Roychowdhury, Amy Webb, Cynthia Timmers, Tanios Bekaii-Saab, Evan Wuthrick. A phase I trial combining MEK-1/2 inhibition in combination with 5-fluorouracil and radiation for locally-advanced rectal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr CT088. doi:10.1158/1538-7445.AM2017-CT088

AbstractIntroductionFamily history (FH) of Alzheimer's disease (AD) affects mitochondrial function and may modulate effects of translocase of the outer mitochondrial membrane 40 kDa (TOMM40) rs10524523 ('523) poly‐T length on memory decline.MethodsFor 912 nonapolipoprotein ε4 middle‐aged adults and 365 aged adults across the AD spectrum, linear mixed models gauged FH and TOMM40 '523 interactions on memory and global cognition between baseline and up to 10 years later. A cerebrospinal fluid mitochondrial function biomarker was also assessed.ResultsFor FH negative participants, gene‐dose preservation of memory and global cognition was seen for “very long” versus “short” carriers. For FH positive, an opposite gene‐dose decline was seen for very long versus short carriers. Maternal FH was a stronger predictor in aged, but not middle‐aged, participants. Similar gene‐dose effects were seen for the mitochondrial biomarker aspartate aminotransferase.DiscussionThese results may clarify conflicting findings on TOMM40 poly‐T length and AD‐related decline.