742 Background: Front-line chemotherapy for patients (pts) with mPDAC typically consists of mFOLFIRINOX or gemcitabine/nab-paclitaxel given until disease progression or intolerable toxicity. For pts with durable disease control on front-line treatment, maintenance therapy that can effectively delay disease progression while preserving quality of life with minimal cumulative toxicity is highly desirable. Ivaltinostat (ival) is a pan-histone deacetylase inhibitor that increases histone acetylation, suppresses cell proliferation, and promotes apoptosis. Preclinical data demonstrated synergy with 5-FU/capecitabine (cape) in mouse models. We report here results of the Phase Ib portion of a Ib/2 trial evaluating the safety and recommended phase 2 dose (RP2D) of this combination to use in a randomized study of ival + cape vs cape as maintenance therapy. Methods: Key eligibility criteria for phase 1b included unresectable or metastatic PDAC; ≥18 years old; ≥1 prior therapy; ECOG PS 0-1; and no known germline BRCA1/2 mutation. Three cohorts were enrolled, receiving ivaltinostat at 60, 125, or 250mg/m 2 iv (weekly on days 1 and 8) in combination with cape (1000mg/m 2 po BID on days 1-14) of a 21-day cycle. 1o objectives: safety, tolerability and RP2D; 2o objectives: pharmacokinetics (PK) of ival + cape. Results: A total of 28 patients were enrolled at the 60 (n=6), 125 (n=10) and 250 (n=12) mg/m 2 ival dose levels. Median prior lines of therapy: 2 (range 1-7). Median age: 67 years (range 50-83). Only one DLT (G4 thrombocytopenia) was observed at 250mg/m 2 dose level. Treatment-emergent AE profile was similar across dose levels, with common TEAEs including fatigue (n=15, 53.6%), nausea (n=14, 50.0%), palmar-plantar erythrodysesthesia syndrome (n=12, 42.9%), diarrhea (n=10, 35.7%), and constipation (n=9, 32.1%). G3 AEs included neutropenia (n=6, 21.4%), anemia (n=4, 14.3%), abdominal pain (n=3, 10.7%) and diarrhea (n=3, 10.7%). G4 AEs included 1 (3.6%) event of neutropenia and 1 (3.6%) of thrombocytopenia. No SAEs related to study drugs occurred in any of the 3 dose cohorts. PK analyses indicated dose proportional increases in exposure with increasing doses of ival. Histone H3K27 acetylation for ival showed the similar trend in optical density evaluation. Across all dose levels and prior treatments, median OS and PFS were 9.6 and 3.3 months, respectively. Conclusions: The combination of ival and cape was generally well tolerated in this heavily pretreated patient population. Ival 250 mg/m 2 is the dose selected for the ongoing randomized study of ival + cape vs cape in the maintenance setting for mPDAC pts post-FOLFIRINOX, which is expected to finish accrual in 2025. Clinical trial information: NCT05249101 .

5105 Background: To tailor care to cancer biology, oncologists offer germline testing to patients with APC. Little is known about whether pre-test counseling conducted by oncologists leads to well-informed, preference-concordant decisions in Veterans with APC. Methods: We conducted a prospective mixed-methods study of consecutive patients with APC who were offered germline testing at an oncology visit at the San Francisco VA. Seven days after the visit, patients were administered the Decisional Conflict Scale (DCS; 16 items scored 0-100, higher = more decisional conflict) and a True/False knowledge test (20 items, scored 0-100% correct). We conducted semi-structured interviews using a theory-informed guide to explore patients’ knowledge, decision-making process, and decisional needs for germline testing. Two coders analyzed the interviews using thematic analysis. Results: Of 68 patients approached, 31 (46%) consented. Mean age was 76y, 21 (68%) were White, and 14 (45%) completed at least college. Mean DCS score was 24 (SD 22); six (19%) patients scored >37.5, which is associated with decision delay. Mean knowledge score was 69% (SD 16); four patients scored < 50%. Patients were least knowledgeable about the results disclosure process (37% correct), presence of privacy laws protecting genetics data (50%), types of test results (50%), and implications of a variant of uncertain significance (50%). Twenty-seven patients (87%) desired germline testing. The most common reasons were to help family and advance research; personal treatment benefits were rarely mentioned. Patients felt the decision was easy, but four experienced uncertainty and decided against testing due to fear of losing service-connected disability benefits. Themes included knowledge deficits about testing benefits/risks, results disclosure process, and impact on disability insurance; presence or absence of autonomy; misconceptions (commercialization or weaponization of genetics data, conflating germline testing and research); disparities due to racial discrimination or homelessness; barriers (poor memory, distress from APC, insufficient details about testing from oncologist, and no access to informational resources); and facilitators (trust in oncologist and the VA, family support, and extra time to make a decision). Patients requested a variable degree of decision support prior to germline testing, ranging from none to a combination of informational materials and coaching. Conclusions: Decisional conflict was low in most but not all patients. Patients’ knowledge deficits, misconceptions, and unawareness of choice due to personal, oncologist, and systemic barriers suggest some did not make informed decisions. To deliver patient-centered oncologist-directed germline testing, future research should focus on developing and implementing decision support personalized to patients’ needs.

71 Background: In a quest to tailor care to tumor biology, oncologists now offer germline testing to all patients with APC. We explored the degree to which germline testing decisions reflect patient preferences about potential benefits and harms discussed by oncologists. Methods: We conducted a prospective qualitative study of consecutive patients with APC who were offered germline testing at an oncology visit at the San Francisco VA. We audio-recorded visits and conducted semi-structured interviews using a theory-informed guide with patients after their visit to understand their decision-making process for germline testing. We analyzed the interviews using the Critical Incident Technique to identify positive or negative deviations from well-informed, preference-based decisions. We also reviewed consent documentation in the electronic health record. Results: Of 61 patients approached, 30 completed interviews after their germline testing discussion. Mean age was 75y; 19 (63%) were White, 9 (30%) Black, and 2 (6%) Other race; and 13 (43%) were service-connected for APC. Twenty-six (87%) patients consented to germline testing; the primary reasons were altruistic (to help family and contribute to knowledge). Four patients (13%) declined testing, all primarily due to the fear of potential loss or reduction of service-connected benefits. All four patients reported they would reconsider testing if assured that these benefits would be protected regardless of test results. Of the four patients, two had initially consented to testing with their oncologist but later changed their minds and did not notify anyone. The two patients received germline testing when they underwent PSA testing, but they were not aware that they had germline testing performed. Both had negative test results, and they therefore did not experience threats to their service-connected benefits. Conclusions: Some Veterans with service-connected benefits for APC decline germline testing due to the fear of potential loss or reduction of these benefits, thereby foregoing potential treatment benefits. An advisory board is working with the Veterans Benefits Administration to protect service-connected benefits for these Veterans. In addition, a few Veterans may agree to germline testing with their oncologist, but then change their minds due to concerns surrounding service-connected benefits. From a quality improvement perspective, the experiences of the patients in this study who changed their minds counts as a near-miss. Although uptake of germline testing was high in this cohort, current workflows may need to be addressed to account for a change of heart, and further research is needed to understand root causes and identify possible remedies of the near-misses. Overall, our findings illustrate the importance of informed consent for germline testing to ensure that results are desired and valued by both oncologist and patient.

TPS4206 Background: Front-line chemotherapy for patients (pts) with advanced or mPDAC typically consists of mFOLFIRINOX or gemcitabine/nab-paclitaxel given until disease progression or intolerable toxicity. For pts with durable disease control on front-line treatment, maintenance therapy that can effectively delay disease progression while preserving quality of life with minimal cumulative toxicity is highly desirable. Ivaltinostat (ival) is a pan-histone deacetylase inhibitor that increases histone acetylation, suppresses PDAC cell proliferation, and promotes apoptosis in PDAC cell lines. Preclinical data demonstrated synergy with 5-FU/cape in mouse models. RP2D of the Phase 1b combination study of ival and cape in advanced pancreatic cancer was ival 250mg/m 2 IV on days 1 and 8 with cape 1000mg/m 2 po days 1-14 of a 21-day cycle. Both ival and cape treatment-related AEs >15% were fatigue, nausea, diarrhea, and decreased appetite. Palmar-plantar erythrodysaesthesia syndrome was also commonly observed; all events were attributed to cape. PK and PD demonstrated dose proportionality. Overall and progression-free survival (PFS) were immature, but 70% of pts who enrolled with measurable disease had stable disease as best response. Several pts remained on study with the longest duration of response about 10 months, as of the data cut off for ASCO GI 2024. Based on this data, a randomized phase 2 study is being conducted comparing the combination of ival and cape versus cape alone in the maintenance setting for pts with mPDAC after first line FOLFIRINOX, mFOLFIRINOX or NALFIRINOX therapy. Methods: Key eligibility criteria for the randomized Phase 2 study include: mPDAC; no evidence of disease progression following at least 16 weeks of front-line FOLFIRINOX or NALIRIFOX at full or modified doses; ECOG PS 0-1; and no known germline BRCA1/2 mutation. A total of 52 pts will be randomized 1:1 to receive cape with or without ival until disease progression, with tumor assessments occurring at 6-week intervals. The primary endpoint is investigator-adjudicated PFS, and the primary analysis will compare PFS distributions in the ival/cape and cape alone arms using a one-sided log rank test with an alpha=0.10. The assumed 6-mo PFS rates are 35% (cape), based on historic data, and 60% (ival/cape), corresponding to an HR of 0.487. Enrollment in the phase 2 study began in January 2024 across multiple sites in the US. Accrual is anticipated to complete 4Q2024. Clinical trial information: NCT05249101 .

666 Background: The standard of care for patient (pts) with advanced or mPDAC typically consists of mFOLFIRINOX or gemcitabine/nab-paclitaxel used in the front-line setting until disease progression (prog) or toxicity. A tolerable maint therapy (tx) that can effectively delay disease prog while preserving quality of life with minimal cumulative toxicity is highly desirable. There is no standard main tx. Ivaltinostat (ival) is a pan-HDAC (histone deacetylation) inhibitor that increases histone acetylation (HA), suppresses PDAC cell proliferation, and promotes apoptosis in PDAC cell lines. Preclinical data demonstrated synergy with 5-FU/capecitabine in mouse models. The phase 1b study will determine an optimal combination of ival and cape followed by a randomized P2 trial of ival plus cape vs cape alone in the maint setting for pts with mPDAC who have not progressed on front-line mFOLFIRINOX. Methods: Key eligibility criteria for P1b include: locally advanced or mPDAC; at least 1 prior line of tx regardless disease prog; ECOG PS 0-1; and no known gBRCA1/2 mutation. Dose-limiting toxicities (DLT) in 3 dose levels of ival, (60, 125, and 250mg/m2 iv weekly on days 1 and 8) in combination with cape (1000mg/m2 po BID on days 1-14) of a 21-day cycle will be evaluated. The primary objective is to evaluate the safety, tolerability and determine the recommended phase 2 dose (RP2D) as well as pharmacokinetics (PK) of ival and cape. Results: As of the date of data-cut, 32 pts had been enrolled at the 60 (7 pts), 125 (14 pts) and 250 (11 pts) mg/m2 dose level, 8 were screen failures and 9 still ongoing with a goal of at least 6 DLT-evaluable pts per dose level. Average prior lines of tx was 3.6 (range 1-5). The median age was 68 (range 51-83) and 21(66%) were males. No DLTs were observed across the 3 dose levels. SAEs occurred in 2 pts that were not related to study drugs. Both ival and cape-related TEAEs were similar except palmar-plantar erythrodysesthesia syndrome (PPES) 9(28%) attributed to cape; fatigue, diarrhea and nausea were the only TEAEs occurred >15%. Two pts had ³grade 3 diarrhea, another pt had cape-related PPES. The TEAE profile was similar across the dose levels. At the time of data-cut there were 6 deaths among pts who discontinued study due to prog. Among 15 pts who had been evaluated for response since baseline, the best ORR were 11 SD(73.3%), 1(6.7%) no RECIST-measurable evidence of disease and 3 PD(20%). PK evaluations for ival indicated dose proportionate increases. The trend of PK observed in this study was similar to the PK trend observed in previous studies. Conclusions: Combination therapy of ival with cape has been well tolerated and the safety and PK/PD data support a RP2D of ival of 250 mg/m2. Clinical trial information: NCT05249101 .

To better understand Veterans' decisions about germline testing, we conducted a single-site, qualitative study of 32 Veterans with advanced prostate cancer. Seven days after oncologist-patient discussions about germline testing, we conducted semi-structured interviews with patients exploring their decision-making process using an interview guide. Four of 14 Veterans with service-connected disability benefits for prostate cancer declined germline testing for fear of losing benefits, as their livelihood depended on these benefits. All 18 Veterans without service-connected benefits agreed to testing. Veterans declining germline testing for this concern can lead to suboptimal cancer care because targeted treatments that could improve their outcomes may go unrecognized. Our findings contributed to new language in the Veterans Benefits Administration Compensation and Pension Manual clarifying that genetic testing showing hereditary predisposition is insufficient to deny service-connected benefits for conditions presumed to be caused by military exposures. Clinicians should communicate this protection when counseling Veterans about genetic testing.

Metastatic pancreatic ductal adenocarcinoma is typically treated with multi-agent chemotherapy until disease progression or intolerable cumulative toxicity. For patients whose disease shows ongoing control or response beyond a certain timeframe (≥3-4 months), options include pausing chemotherapy with close monitoring or de-escalating to maintenance therapy with the goal of prolonging progression-free and overall survival while preserving quality of life. There is currently no universally accepted standard of care and a relative dearth of randomized clinical trials in the maintenance setting. Conceptually, such therapy can entail continuing the least toxic components of a first-line regimen and/or introducing novel agent(s) such as the poly(ADP-ribose) polymerase inhibitor olaparib, which is presently the only approved drug for maintenance treatment and is limited to a genetically defined subset of patients. In addition to identifying new therapeutic candidates and combinations in the maintenance setting, including targeted agents and immunotherapies, future research should focus on better understanding this unique biologic niche and how treatment in the maintenance setting may be distinct from resistant/refractory disease; identifying molecular predictors for more effective pairing of specific treatments with patients most likely to benefit; and establishing patient-reported outcomes in clinical trials to ensure accurate capture of quality of life metrics.

TPS4181 Background: The mainstay of treatment (TX) for pts with advanced or mPDAC consists of CT, with FOLFIRINOX and gemcitabine (gem)/nab-paclitaxel currently representing the front-line standards of care. TX is generally continued until either dis progression (progr) or cumulative toxicity, with pts often reaching a plateau in response after 4-6 mos. For those who have achieved dis control (stable dis or better) on front-line CT, a maint TX strategy that can effectively delay dis progr while preserving quality of life with minimal cumulative toxicity is highly desirable. However, aside from PARP inhibition in the subset of PDAC pts with gBRCA mutated dis, there is no current standard of care in this maint setting. Ival is a pan-HDAC (histone deacetylation) inhibitor that increases histone acetylation (HA), suppresses PDAC cell proliferation, and promotes apoptosis in PDAC cell lines in a dose-dependent manner. It has demonstrated synergy with 5-FU in cholangiocarcinoma cell lines and shows promising antitumor activity when combined with cap in syngeneic PDAC mouse models. On these bases, we are conducting a ph1b/randomized ph2 trial of ival plus cap vs cap alone in the maint setting for pts with mPDAC who have not progressed on front-line FOLFIRINOX. Methods: Key eligibility criteria include pts with mPDAC; no evidence of dis progr following at least 16 wks of front-line FOLFIRINOX at full or modified doses; ECOG PS 0-1; and no known gBRCA1/2 mutation. The study includes an initial dose-esc ph1b evaluating 3 dose levels of ival, (60, 125, and 250mg/m2 iv weekly on days 1 and 8) in combination (comb) with cap (1000mg/m2 po BID on days 1-14) of a 21-day cycle, using a standard 3 + 3 dose-esc design. Of note, ival 250 mg/m2 represents the RP2D identified in prior clinical studies of this agent both as monotherapy in solid tumors and in comb with gem/erlotinib in advanced PDAC pts. In the ph2 portion, pts will be randomized 1:1 to receive either ival plus cap or cap alone, in 21-day cycles, until dis progr, with tumor assessments occurring at 6-wk intervals. Blood will be collected at pre-specified serial timepoints for pharmacodynamic assessments, including HA of PBMCs. Primary endpoint for ph2 is investigator-adjudicated PFS. The primary analysis will compare PFS distributions in the ival/cap and cap alone arms using a one-sided log rank test with an alpha = 0.10. The assumed true 6-mo PFS rates are 35% (cap), based on historic data, and 60% (ival/cap), which corresponds to an HR of 0.487. Assuming an accrual duration of 18 mos and a dropout/lost to follow-up rate of 10%, the estimated total number of pts in the randomized ph2 portion is 52 (26 per arm). Enrollment is expected to being in spring 2022 across 25 U.S. sites.

The gut microbiome is important in human health and disease. Recent studies have begun to elucidate its specific role in colorectal cancer. The gut microbiome seems to play an integral role in colorectal cancer initiation and progression, and oncologic drug metabolism and toxicity. This review examines the associations between the gut microbiome and colorectal cancer initiation, progression, and oncologic drug metabolism, highlighting proposed mechanisms and landmark publications in this field. It also discusses potential methods of modulating the gut microbiome, underscoring the gaps in current understanding, and ends with a clinically relevant overview of microbiome research considerations and study design .

Objectives Germline genetic testing is universally recommended for patients with pancreatic cancer to guide therapeutic selection, but tumor molecular profiling (TMP) is not. We aimed to determine the real-world additional diagnostic benefit of TMP after germline testing for detecting therapeutically actionable alterations. Methods Medical records and genetic test reports were reviewed for all patients who underwent germline testing and TMP at the University of California San Francisco during January 2016–January 2020. The detection rate of actionable alterations with germline testing alone was compared to that with both germline testing and TMP. Results Among 738 eligible patients, 144 (20%) met study criteria. Germline testing detected 10 actionable alterations in 10 patients. Tumor molecular profiling identified 3 new therapeutic targets among these 10 patients and 45 targets in 41 additional patients, increasing the number of patients with actionable findings from 10 (7%) to 51 (35%). Most actionable alterations (35/58, 60%) involved genes associated with the Homologous Recombination DNA Damage Repair pathway. Conclusions Tumor molecular profiling after germline testing increased the detection of actionable alterations by 5-fold. Tumor molecular profiling is a necessary complement to germline genetic testing to fully inform therapeutic decision making for all patients with pancreatic cancer.

Background Germline genetic testing is universally recommended for patients with pancreatic cancer, but testing remains infrequent. In May 2018, we implemented a systematic patient intake workflow featuring an in-clinic genetic testing station (GTS) at the University of California San Francisco (UCSF) to expedite genetic counseling and facilitate sample collection. We sought to determine the impact of this innovation on rates of genetic counseling and testing. Methods Medical records, patient intake records, and genetic test reports were retrospectively reviewed for new patients with pancreatic cancer eligible for germline testing at UCSF from May 2018 to May 2019. Primary outcomes included the rate of offered genetic counseling and confirmed germline testing. Data were compared for periods before and after GTS implementation. Associations between demographic characteristics and testing rates were assessed. Results Genetic counseling/testing was offered to 209 (94%) of 223 eligible patients, and 158 (71%) completed testing (135 at UCSF, 23 elsewhere). Compared with a traditional referral-based genetic counseling model, confirmed testing increased from 19% to 71%, patient attrition between referral and genetics appointment decreased from 36% to 3%, and rate of pathogenic variant detection increased from 20% to 33%. Patients who were younger, identified as non-Hispanic White, and spoke English as a primary language were more likely to complete testing. Conclusions Implementation of a systematic patient intake workflow and in-clinic GTS resulted in the highest reported real-world rate of germline testing for patients with pancreatic cancer. Health care disparities were identified and will guide future innovation. This report provides a model for other centers to create a similar testing infrastructure. Implications for Practice This study demonstrates that a systematic patient intake workflow and associated in-clinic genetic testing station improve delivery of genetic counseling and completion of germline testing for patients with pancreatic cancer. This study achieved, to the authors' knowledge, the highest real-world rate of confirmed genetic testing in this patient population. This article describes this innovation in detail to guide replication at other medical centers and facilitate guideline-concordant care for patients with pancreatic cancer. This infrastructure can also be applied to other cancers for which germline testing is recommended.

Mismatch repair protein deficiency occurs in 0.8-2% of pancreatic ductal adenocarcinomas and confers susceptibility to immunotherapy. Herein, we report the case of a patient with Lynch syndrome-associated, locally advanced mismatch repair protein deficiency pancreatic ductal adenocarcinomas who demonstrated a sustained response to second-line treatment with pembrolizumab, but eventually developed immune-related diabetic ketoacidosis requiring discontinuation of treatment. He has since remained in remission, off treatment, over the following 3 years, with regular surveillance showing no clinical or radiographic evidence of disease progression. The patient's unusual disease course raises the question of whether this serious immune-related adverse event affecting the organ of malignant involvement may have predicted his remarkable and durable response.

6522 Background: A variety of biologic, socioeconomic, and treatment-related factors may contribute to the racial/ethnic disparities observed in pancreatic ductal adenocarcinoma (PDAC) outcomes. As tumor molecular profiling (TMP) is now recommended for patients (pts) with advanced PDAC to inform treatment selection, we hypothesized that rates of TMP, detection of actionable alterations (AA), and use of molecularly-targeted treatments differ across different racial/ethnic groups and may contribute to disparate outcomes. Methods: This retrospective analysis included all Non-Hispanic White (NWH), Asian, Hispanic/Latinx (H/L), and Black/African American (B/AfrAm) pts with PDAC who underwent TMP at UCSF over a 4-yr period. Medical records were reviewed for demographic and disease-specific data. Alterations classified as ‘pathogenic’ or ‘likely pathogenic’ in TMP clinical reports were included, and were categorized as ‘actionable’ if there was clinical or preclinical evidence of benefit from targeted therapy in any cancer. Associations between NHW and other groups were tested with Fishers exact test. Results: Between 1/2016-1/2020, 159/727 (22%) pts underwent PDAC TMP. 60 AA were detected in 54 pts. Rates of TMP or AA detection were not associated with racial/ethnic group (Table). Most AA (33/60, 55%) were associated with the Homologous Recombination DNA Damage Repair (HR-DDR) pathway ( ARID1A n = 15 , ATM n = 7 , and BRCA1 n = 5). Other common AA included PIK3CA alterations (n = 6), CDK4/6 amplifications (n = 5), AKT2 amplifications (n = 4) and KRAS G12C mutation (n = 4). Molecular targets differed between groups (HR-DDR genes comprised 55% AA in NHW vs 100% in H/L, p = 0.03). Regarding treatment, rates of platinum chemotherapy for HR-DDR gene-altered PDAC differed significantly between groups. Three NHW pts with HR-DDR alterations received a PARP-inhibitor +/- ATR inhibitor. Conclusions: To our knowledge, this is the first study to report PDAC TMP rates and therapeutic implications across racial/ethnic groups. Acknowledging the limitations of sample size and what defines AA, we observed no significant differences in rates of testing nor AA detection. Further study is needed to evaluate whether rates of molecularly-informed treatment selection contribute to racial/ethnic disparities in clinical outcomes. As therapeutic advances increase the likelihood of identifying AA, equitable access to both TMP and targeted treatments must be ensured for all pts with PDAC.[Table: see text]

IntroductionNarrative competence comprises the skills of acknowledging, interpreting, and acting on the stories of others. Developing narrative competence is integral to providing patient-centered care. In January 2020, we designed a narrative medicine curriculum in which medical students at the San Francisco Veteran Affairs (VA) Medical Center in California participated as interviewers in My Life My Story (MLMS) program. The curricular objectives for medical students were to build life story skills, appreciate the impact of storytelling on a veteran's health care experience, and understand the VA mission.ObservationsStudents attended a training session to build narrative medicine skills, interviewed a veteran, entered their life story into the health record, and attended a second session to debrief. Students completed a survey after the MLMS program. From March to July 2020, COVID-19-related restrictions prompted transition of the program to a virtual format. Sixty-two veteran stories were collected, and 54 (87%) veterans requested that their stories be entered into the health record. Students reported that the program helped them develop life story collection skills and understand how sharing a life story can impact a veteran's experience of receiving health care. There was no statistically significant difference in survey responses whether interviews were in person, by telephone, or over video.ConclusionsA curriculum incorporating MLMS effectively taught narrative medicine skills to medical students. The program achieved its objectives despite curricular redesign for the virtual setting. This report details an adaptation of a life story-focused narrative medicine curriculum to a virtual environment and can inform similar programs at other VA medical centers.

BACKGROUND/AIM:Oxaliplatin-induced neurotoxicity (OIN) can be severe and dose-limiting with clinically significant symptoms that persist for years. Few published reports have described postoperative exacerbation of OIN and more longitudinal data are needed to better characterize the phenomenon.PATIENTS AND METHODS:We identified 13 patients diagnosed with colon (n=7), rectal (n=4) or pancreatic (n=2) cancer who experienced postoperative OIN exacerbation at our medical center. Charts were reviewed for demographic and clinical data regarding OIN.RESULTS:OIN exacerbation was documented 0.5-7.0 months after the first surgery following oxaliplatin exposure, with a median duration of 10.6 months (range=1.4-86.1 months). OIN exacerbation persisted in 3/13 patients at last follow-up, and improved to pre-operative levels in 6/13 patients (with complete resolution in 4/13) within a median of 3.6 months from initial exacerbation.CONCLUSION:Given the widespread use of oxaliplatin in neoadjuvant and first-line treatment for gastrointestinal cancers, further study is warranted to prospectively and systematically define risks for postoperative OIN exacerbation.