Is There a Benefit to Adjuvant Chemotherapy in Resected, Early Stage Pancreatic Ductal Adenocarcinoma?

BACKGROUND

The role of systemic therapy for Stage IA pancreatic ductal adenocarcinoma (PDAC) is unclear. The aim of our study was to evaluate the impact of adjuvant chemotherapy (AC) on survival in patients with early stage disease.

METHODS

The National Cancer Database was queried from 2006 to 2017 for resected pT1N0M0 (Stage 1A) PDAC. Exclusion criteria included neoadjuvant therapy, radiation, or those who suffered a 90-day mortality.

RESULTS

Of the 1526 patients included in the study, 42.2% received AC and 57.8% underwent surgery alone. Patients who received AC were younger, had fewer comorbidities, and were more likely to have private insurance, compared with those treated with surgery alone. Patients who received AC had longer median overall survival (OS) compared with those who underwent surgery alone (105.7 months vs 72.0 months, p < 0.01). Subset analyses based on individual "good" prognostic features (size ≤ 1.0 cm, lymphovascular invasion negative, well/moderately differentiated, margin negative resection) demonstrated improved OS with AC. Following propensity score matching based on key clinicopathologic features, AC remained associated with improved median OS (83.7 months vs 59.8 months, p < 0.01). However, in the cohort with body/tail tumors (101.2 months vs 95.0 months, p = 0.19) and those with all "good" prognostic features (95.9 months vs 90.6 months, p = 0.15), AC was not associated with improved survival.

CONCLUSIONS

In resected, Stage IA PDAC, AC is associated with improved overall survival in the vast majority of patients; however, in select cohorts the role of AC is unclear. Further study is needed to tailor treatment to individual patients with PDAC.

A phase 1b study of sotorasib, a specific and irreversible KRASG12C inhibitor, in combination with other anticancer therapies in advanced colorectal cancer (CRC) and other solid tumors (CodeBreaK 101)

TPS214

Background: Approximately 3% of patients (pts) with CRC have the oncogenic Kirsten rat sarcoma viral oncogene homolog (KRAS) p.G12C mutation. Sotorasib, a small molecule that specifically and irreversibly inhibits the KRAS G12C mutant protein, has demonstrated modest clinical activity and no dose-limiting toxicities as a single agent in heavily pretreated pts with KRAS p.G12C-mutated CRC. The combination of sotorasib with other anticancer therapies, such as EGFR or MEK inhibitors, may enhance antitumor efficacy and counteract potential escape mechanisms. Other attractive partners for sotorasib in CRC include biologics and chemotherapy combinations. The CodeBreaK 101 master protocol is designed to evaluate safety, tolerability, pharmacokinetics (PK), and efficacy of multiple sotorasib-based combinations in pts with KRAS p.G12C mutated solid tumors. Key subprotocols with CRC combination treatment arms are highlighted here. Methods: This is a phase 1b, open-label study evaluating sotorasib alone and in combination regimens in pts with advanced KRAS p.G12C mutated CRC, NSCLC, and other solid tumors. Key regimens being explored in CRC include (1) Subprotocol A: Sotorasib + trametinib (MEK inhibitor) +/- panitumumab (EGFR inhibitor), (2) Subprotocol H: Sotorasib + panitumumab and sotorasib + panitumumab + FOLFIRI, and (3) Subprotocol M: Sotorasib + bevacizumab-awwb + FOLFIRI or FOLFOX. Key eligibility criteria include advanced or metastatic solid tumor with KRAS p.G12C mutation identified through molecular testing in treatment-naïve and pretreated patients depending on cohort. Primary endpoints include dose-limiting toxicities and treatment-emergent or treatment-related adverse events. Secondary endpoints include PK profile of combination regimens and efficacy (objective response, disease control, duration of response, time to response, and progression-free survival assessed per RECIST 1.1, and overall survival). Enrollment is ongoing. Contact Amgen Medical Information for more information: medinfo@amgen.com (NCT04185883). Abbreviations: EGFR = epidermal growth factor receptor; FOLFIRI = 5-fluorouracil + leucovorin + irinotecan; FOLFOX = 5-fluorouracil + leucovorin + oxaliplatin; MEK = mitogen-activated protein kinase. Clinical trial information: NCT04185883.

Cancer Commons’ virtual tumor board program: A patient-centric advisory panel and real-world data registry

527

Background: We initiated a nationwide Virtual Tumor Board (VTB) program for pancreatic cancer (PC) patients (pts). The VTB consists of oncology experts and serves as an advisory panel by providing information on treatment (Tx) options based on a comprehensive review of patients’ oncologic history. Personalized Tx options and their rationales are provided and outcomes tracked in a prospective registry (XCELSIOR). Methods: PC pts who participated in XCELSIOR shared access to their full medical records, which were collected, processed, and abstracted. The panel reviewed cases asynchronously through an interactive platform followed by a VTB which was held weekly through videoconferencing. Tx options were summarized into a written report and provided to patients and their physicians. Outcomes and quality of life are tracked longitudinally through an IRB-approved 21CFR11 compliant observational registry (XCELSIOR). Results: From 9/2020 to 8/2021, the VTB reviewed 79 unique cases; 56% were male; median age at diagnosis was 66 (50-87). At the time of VTB, 68 (87%) had metastatic disease and 8 (10%) had locally advanced disease. Median prior therapy lines was 2 (0-9), with 26 (35%), 24 (32%), 6 (8%), and 19 (25%) pts having received 1, 2, 3 and 4+ lines of therapy, respectively. Median time from diagnosis for pts presenting after 1, 2, and 3+ lines of prior Tx was 9.5, 11, and 17.5 months, respectively. First-line Tx was FOLFIRINOX in 40 (53%) pts and gemcitabine/nab-paclitaxel in 22 (29%) pts. At the time of VTB, 32 (37%) of patients had stable disease, 23 (26%) had disease progression, 18 (21%) had recently started a new Tx, 7 (8%) were responding to Tx, 3 (3%) had stable disease on imaging but rising CA 19-9, and 4 (4%) were others. Prior to VTB, 69 (87%) pts had molecular profiling results available. Collectively the VTB provided 375 Tx and diagnostic (NGS, imaging, etc.) options with a median of 4 (1-12) options per patient. As of 9/8/2021, 87 VTB reports were provided. Of 25 instances of ‘no Tx decision’, 10 (40%) are deceased, 10 (40%) are stable, and 5 (10%) had other reasons. Of the 25 people who started a subsequent Tx, 14 (56%) were identified by the VTB. These included 9 (64%) FDA-approved, 3 (21%) off-label, and 2 (14%) on-trial Tx. Tx not identified by the VTB included 3 (33%) FDA-approved, 2 (22%) off-label, 2 (22%) on-trial, and 2 (22%) local Tx. Conclusions: We present our experience of utilizing a platform for patients to receive a virtual tumor board review and utilize an IRB-approved registry as a learning system. Early data indicate successes in identifying treatment and clinical trial opportunities. Future steps include streamlining communication with primary oncologists and enhancing access to treatments. NCT03793088.

LRP1B and GRM3 expression in colorectal cancer

177

Background: LRP1B is a member of the low-density lipoprotein receptor family and a tumor suppressor found to be downregulated in colon cancer (CRC). GRM3 is a receptor of glutamate, an amino acid and neurotransmitter. Inhibition of GRM3 reduces CRC cell growth. Recent data from CALGB/SWOG 80405 suggests that mutations (MT) of either LRP1B or GRM3 are associated with better and worse overall survival (OS) in patients treated with bevacizumab (Bev), respectively. We investigate the association of LRP1B or GRM3 mRNA levels with outcomes. Methods: A total of 13,780 CRC tumors (male 7,497, female 6,283) underwent comprehensive molecular profiling (Caris Life Sciences). Analyses included next-generation sequencing of DNA (592 genes, NextSeq, WES, NovaSEQ) and RNA (NovaSeq). Significance with multiple correction was indicated with q, otherwise p value. Gene Set Enrichment Analyses (GSEA) were performed (significance p <.05). A Consensus Molecular Subtype (CMS) calling algorithm was developed using mRNA levels (transcripts per million; TPM). Time on treatment (TOT) with Bev was extracted from insurance claims. Results: Male patients had higher GRM3 expression (median TPM.55 vs..52, p <.001). GRM3 and LRP1B were both elevated in brain metastases (1.95 vs..40, q<.01;.53 vs..16, q<.01) and enriched in CMS4 subtype (both p <.001). Overexpression of GRM3 and LRP1B were significantly associated with MSS (.11 vs..07, p <.0001;.54 vs..39, p <.0001) and TMB low status (.11 vs..08, p <.0001;.54 vs..40, p <.0001). For MSS tumors, high LRP1B was associated with lower MT rates of APC (76% vs. 78%), KRAS (49% vs. 51%) and PIK3CA (15% vs. 17%). For MSI tumors, high LRP1B correlated with higher MT of MSH6 (41% vs. 32%), BRCA2 (28% vs. 20%) and PMS2 (12% vs. 6%). MSS tumors with high GRM3 had more APC (79% vs. 75%), less KRAS (47% vs. 52%) and SMAD4 (12% vs. 16%) MT and MSI with high GRM3 carried more APC (42% vs. 35%) and RAD50 (18% vs. 8%) MT. MSS tumors with low LRP1B showed upregulation of the EIF2 pathway while MTOR, RAB, and CDC42 pathways were enriched in MSI with low LRP1B. CDC42 and MTOR pathways were enriched in MSS tumors with low GRM3, and MSI with low GRM3 displayed enrichment of EIF2 and Notch pathways. In MSS tumors, both LRP1B and GRM3 were prognostic and associated with better survival (HR.66, 95% CI [.56-.78], p <.0001 for LRP1B; HR.79, 95% CI [.68-.92], p <.01 for GRM3) and high expression of either one was also associated with better prognosis for patients treated with Bev (HR.85, 95% CI [.70-.92], p <.01 for LRP1B; HR 0.88, 95% CI [.77-.99], p <.05 for GRM3). Conclusions: LRP1B and GRM3 appear to be important regulators in CRC because of their prognostic value and association with response to bevacizumab treatment. Both LRP1B and GRM3 are associated with pathways of cell cycle progression, cell migration, and DNA repair. A better understanding of their role in angiogenic signaling is critical to develop more effective strategies to improve response to bevacizumab or immunotherapy.

Abstract P05-01: A phase 1b study evaluating the safety and efficacy of sotorasib, a KRASG12C inhibitor, in combination with trametinib, a MEK inhibitor, in KRAS p.G12C-Mutated Solid Tumors

Background KRAS p.G12C is an oncogenic driver in solid tumors, including non-small cell lung cancer (NSCLC) and colorectal cancer (CRC). Sotorasib, a specific, irreversible KRASG12C inhibitor, was recently approved by the FDA for treatment of adults with KRAS p.G12C-mutated locally advanced or metastatic NSCLC who received at least one prior systemic therapy. Sotorasib combined with trametinib, a selective allosteric MEK1/MEK2 inhibitor, displayed synergist antitumor activity in tumor xenografts. Here we report the first safety and interim efficacy of sotorasib in combination with trametinib in advanced KRAS p.G12C-mutated solid tumors in this phase 1b CodeBreaK101 master study. Methods In this dose exploration/expansion study, patients (pts) with KRAS p.G12C-mutated solid tumors were treated with 960 mg QD sotorasib and trametinib (1 or 2 mg QD). For NSCLC, prior anti-PD1/PD-L1 and/or platinum-based combination chemotherapy and targeted therapy (if applicable) was required. For CRC, at least 1 prior systemic regimen including fluoropyrimidine, oxaliplatin, and irinotecan-based regimens was required. 1° endpoint was safety/tolerability. 2° endpoint was efficacy. Results Based on a July 12, 2021 snapshot, 41 pts (22 male, median age: 60.0 y [34-84]) were enrolled and treated with combination of sotorasib and trametinib (18 pts NSCLC, 18 pts CRC, 5 pts other). Thirty-three pts (80.5%) received ≥2 prior lines of therapy (range, 0–8); 11 pts (26.8%) received prior KRASG12C inhibitor. Median treatment duration of the sotorasib and trametinib combination was 84.0 days (Q1, 42.0; Q3, 140.0). No new or unexpected toxicities were identified. The most common treatment-related adverse events (TRAEs) included diarrhea (43.9% pts), rash (34.1% pts), nausea (29.3% pts), and vomiting (22.0% pts), predominantly ≤grade 2. Ten pts (24.4%) discontinued sotorasib and/or trametinib due to a TRAE (2 pts-diarrhea). One dose-limiting toxicity (grade 3 maculo-papular rash, trametinib-related) was observed out of 33 pts treated with 2 mg trametinib/960 mg sotorasib QD. For the 1 mg trametinib/960 mg sotorasib QD CRC exploration cohort (N=3); 1 confirmed partial response (PR) and 1 stable disease (SD) were reported in pts with prior KRASG12C inhibitor; 1 SD was reported in a KRASG12C inhibitor-naïve pt. For the 2 mg trametinib/960 mg sotorasib QD CRC cohort (N=15), all 4 pts with prior KRASG12C inhibitor had SD; for naïve pts, 1-confirmed PR, 7-SD, and 3-progressive disease (PD) were reported. In NSCLC pts (N=18) treated with 2 mg trametinib/960 mg sotorasib QD, of pts with prior KRASG12C inhibitor, 2-SD and 1-PD were reported; of naïve pts, 3-confirmed PR, 10-SD, 1-PD, and 1-not evaluable were reported. Conclusions Combination of sotorasib and trametinib is safe and tolerable. The maximum tolerated dose tested was 2 mg trametinib/960 mg sotorasib QD. Antitumor activity was observed including responses in pts with prior KRASG12C inhibitor. Triplet combination therapy of sotorasib with trametinib and panitumumab currently are under investigation in solid tumors.

Citation Format: Suresh Ramalingam, Marwan Fakih, John Strickler, Ramaswamy Govindan, Bob T. Li, Sarah Goldberg, David Gandara, Timothy Burns, Minal Barve, Catherine Shu, Richard Frank, Davendra Sohal, Pegah Jafarinasabian, Tian Dai, Omar Mather, David Hong. A phase 1b study evaluating the safety and efficacy of sotorasib, a KRASG12C inhibitor, in combination with trametinib, a MEK inhibitor, in KRAS p.G12C-Mutated Solid Tumors [abstract]. In: Proceedings of the AACR-NCI-EORTC Virtual International Conference on Molecular Targets and Cancer Therapeutics; 2021 Oct 7-10. Philadelphia (PA): AACR; Mol Cancer Ther 2021;20(12 Suppl):Abstract nr P05-01.

Moving Beyond the Momentum: Innovative Approaches to Clinical Trial Implementation

Despite efforts to enhance enrollment and the merger of national cooperative groups, < 5% of patients with cancer will enroll into a clinical trial. Additionally, clinical trials are affected by a lack of diversity inclusive of minority patients, rural residents, or low-income individuals. COVID-19 further exacerbated known barriers of reduced physician-patient interaction, physician availability, trial activation and enrollment, financial resources, and capacity for conducting research. Based on the cumulative insight of academic and community clinical researchers, we have created a white paper identifying existing challenges in clinical trial conduct and have provided specific recommendations of sustainable modifications to improve efficiency in the activation and conduct of clinical trials with an overarching goal of providing improved access and care to our patients with cancer.

Ceralasertib-Mediated ATR Inhibition Combined With Olaparib in Advanced Cancers Harboring DNA Damage Response and Repair Alterations (Olaparib Combinations)

Poly (ADP-ribose) polymerase (PARP) inhibitors have emerged as promising therapy in cancers with homologous recombination repair deficiency. However, efficacy is limited by both intrinsic and acquired resistance. The Olaparib Combinations basket trial explored olaparib alone and in combination with other homologous recombination–directed targeted therapies. Here, we report the results of the arm in which olaparib was combined with the orally bioavailable ataxia telangiectasia and RAD3-related inhibitor ceralasertib in patients with relapsed or refractory cancers harboring DNA damage response and repair alterations, including patients with BRCA-mutated PARP inhibitor–resistant high-grade serous ovarian cancer (HGSOC).

Abstract 1088: Advancing non-cytotoxic DNMT1-targeting to treat chemorefractory pancreatic cancer

The key epigenetic regulator DNA methyltransferase 1 (DNMT1) is a scientifically validated target in p53-null chemorefractory cancers like pancreatic ductal adenocarcinoma (PDAC) since DNMT1-depletion effects cancer cell cycle exits by p53-independent epithelialization. DNMT1 can be depleted by the pyrimidine nucleoside analog pro-drugs decitabine (Dec) or 5-azacytidine (5Aza). However, PDAC clinical trials with Dec/5Aza disappointed. In pre-clinical and clinical analyses, we found resistance was caused by configurations of pyrimidine metabolism in PDAC cells that forestall Dec or 5Aza processing into DNMT1-depleting nucleotide: high expression of cytidine deaminase (CDA) that rapidly catabolizes Dec/5Aza; and suppression of deoxycytidine kinase (DCK) and uridine kinase 2 (UCK2) that rate limit Dec/5Aza pro-drug processing respectively. Accordingly, combination of Dec with a CDA clinical inhibitor, tetrahydrouridine (THU), enabled DNMT1-depletion and PDAC cytoreduction in vitro and in Dec/gemcitabine-refractory PDAC pre-clinical in vivo models. We then conducted a pilot clinical trial in 13 patients with chemorefractory PDAC given oral THU ~10 mg/kg/day combined with decitabine ~0.2 mg/kg/day, for 5 consecutive days, then twice weekly. This Phase 2 was based on several PK/PD studies in human subjects showing potent non-cytotoxic DNMT1-targeting in myeloid cells. Yet again, there were no meaningful clinical responses in the patients. A reason for this was a surprising lack of neutropenia, the most sensitive indicator of systemic DNMT1-targeting. Upon measuring plasma CDA enzyme activity, we found a &gt;10-fold increase in patients with metastatic vs resectable PDAC. Thus, CDA activity is increased not only locally but also systemically in metastatic PDAC, suggesting a need for higher THU doses. We have also observed DCK downregulation, necessary for Dec/gemcitabine uptake and processing, as a cause of PDAC resistance to Dec/gemcitabine. To counter this mechanism, we discovered that 5Aza upregulates DCK as an adaptive response to 5Aza-mediated decrease in dCTP, while Dec upregulates UCK2 (that mediates 5Aza uptake) as an adaptive response to Dec mediated reductions in dTTP. Thus, we alternated Dec with 5Aza in an in vivo model of gemcitabine-resistant PDAC, to exploit their mutual cross-priming, together with THU to inhibit CDA: median vehicle control tumor measurements 972 mm3(range 726-1267.5); median THU-Dec/THU-5Aza 16 mm3 (range 0-87.5); P&lt;0.00001). A non-cytotoxic, epithelial-differentiation based mechanism was confirmed by significant increases in pancreatic epithelial markers while apoptosis markers were unchanged. In sum, metabolism-based resistance to Dec/5Aza can be countered by clinically relevant modifications to treatment, such as alternating doses of THU/Dec and THU/5Aza, for non-cytotoxic p53-independent therapy, a modality distinct from chemoradiation.

Citation Format: Rita Tohme, Francis Enane, Caroline Schuerger, Xiaorong Gu, Melissa Fishel, John Pink, Daniel Lindner, Davendra Sohal, Yogen Saunthararajah. Advancing non-cytotoxic DNMT1-targeting to treat chemorefractory pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1088.

Predictors of clinical outcomes in patients undergoing curative treatment for esophageal or gastroesophageal junction adenocarcinoma

e16067

Background: Management of locally advanced esophageal and gastroesophageal junction (E/GEJ) adenocarcinoma is typically managed with neoadjuvant treatment followed by surgery. Clinical outcomes remain suboptimal and a considerable proportion of patients develop recurrence. However, prognostic and predictive factors are not well-defined. We thus aimed to identify any factors that were associated with disease recurrence and decreased overall survival (OS) among patients with E/GEJ adenocarcinoma treated with curative intent. Methods: A retrospective study spanning 2011-2020 was performed, which identified 56 patients who underwent esophagectomy for E/GEJ adenocarcinoma at the University of Cincinnati. Data on baseline demographic and clinical characteristics, treatment details, pathologic outcomes, recurrence patterns, and survival were extracted from the electronic medical record. Predictors of recurrence and OS, using multivariable logistic regression and Cox proportional hazards analyses, respectively, were identified using all potential predictors and parsimonious modeling. The study was approved by the UC IRB; statistical analyses were performed using SAS 9.2; 95% confidence intervals and two-sided p-values were calculated. Results: Of the 56 patients included, 50 (89%) were White and 6 (11%) were Black; 46 (82%) were male and 48 (85%) were current or former smokers. Tumor location was E in 37 (66%) and GEJ in 19 (34%) patients; 30 (64%) had cT3 or cT4 tumors and 27 (55%) had node-positive disease. Neoadjuvant treatment included platinum-based chemotherapy for 43 (77%) and radiation for 40 (71%) patients; all patients underwent esophagectomy. Median OS for the entire cohort was 4.2 (95% CI 1.8-NR) years and 23(41%) had recurrence after resection. Multivariable modeling showed body mass index (BMI) < 25 (OR vs. BMI ≥ 25: 5.41, 95% CI 1.4-20.4, p = 0.01) to be associated with recurrence; a higher pathologic T stage showed a trend toward increased risk (pT stages 1, 2, and 3 patients (vs. pT 0) were 0.2, 1.1, and 2.5 times more likely to have recurrent disease, respectively. OS was inferior for patients with recurrence (HR for death, vs. no recurrence: 5.42, 95% CI 2.1-13.8, p < 0.001) and a baseline ECOG PS ≥2 (HR vs. ECOG PS < 2: 2.36, 95% CI 0.87-6.4, p = 0.09). Conclusions: In this dataset of patients with E/GEJ adenocarcinoma treated with curative-intent resection, baseline clinical parameters of lower BMI and worse ECOG PS (rather than disease characteristics such as T and N stage) were the main predictors of recurrence and decreased OS. These findings suggest that improving clinical outcomes may at least partly depend on prehabilitation targeting nutrition and physical therapy for patients undergoing curative treatment for E/GEJ adenocarcinoma.

Body composition measurements and overall survival in patients with resectable pancreatic adenocarcinoma receiving neoadjuvant chemotherapy: Analysis from SWOG S1505

4131

Background: Sarcopenia and sarcopenic obesity have been associated with overall survival (OS) in patients (pts) with borderline resectable and advanced pancreatic ductal adenocarcinoma (PDA), but little is known about the effect of body composition on OS in pts with resectable PDA. We examined the relationship between skeletal muscle and adipose tissue measurements on baseline computed tomography (CT) and OS of pts with resectable PDA in a secondary analysis of SWOG S1505 (NCT02562716). Methods: SWOG S1505 enrolled pts with resectable PDA who were randomized to receive neoadjuvant FOLFIRINOX or gemcitabine-nab paclitaxel, followed by surgical resection. Baseline axial CT images at the L3 level were analyzed with externally validated software and measurements were recorded for skeletal muscle area (SMA), density (SMD) and index (SMI); visceral adipose tissue area (VATA) and density (VATD); and subcutaneous adipose tissue area (SATA) and density (SATD). Sarcopenia was defined as SMI < 52 cm2/m2 for men and < 39 cm2/m2 for women; sarcopenic obesity was defined as sarcopenia and a body mass index (BMI) >30 kg/m2. The relationships between CT metrics and OS were analyzed using Cox regression models, with 95% CI. Statistical significance was defined as p < 0.05. Results: Of 98 pts with available baseline abdominal CT, 8 were excluded for scan quality, resulting in 90 evaluable cases: 51 men (57%), 39 women (43%); mean age, 63.2 years, SD 8.5; mean BMI, 29.3 kg/m2, SD 6.4; 80 (89%) White, 6 (7%) Black, and 4 (4%) unknown. Sarcopenia was present in 32 (36%) and sarcopenic obesity in 10 (11%) patients. Univariable analyses for the variables of interest indicated VATA (HR 1.24; 0.97-1.60; p = 0.09) and SMD (HR 0.75; 0.57-0.98; p = 0.04) were associated with OS. Analyses adjusted for sex, race, age, BMI, performance score, contrast use, sarcopenia, and sarcopenic obesity showed VATA was associated with OS (HR 1.58; 1.0-2.51; p = 0.05). No significant difference in median OS was observed between pts with vs. without sarcopenia (OS 23.6 [19.3-NA] vs. 27.9 months [18.6-NA], respectively). Pts with vs. without sarcopenic obesity had lower median OS: 18.6 (14.7-NA) vs. 25.1 (10.5-46.0) months, respectively, but this difference was not statistically significant (HR 1.90, 95%CI 0.81-4.47, p = 0.14). Conclusions: This is one of the first studies to systematically evaluate body composition parameters in a prospective trial of patients with resectable PDA who received neoadjuvant chemotherapy. We found that visceral fat (VATA) is a prognostic marker in this population, but that sarcopenia may not be predictive in early PDA. Further studies to define the impact of longitudinal changes in body composition on individual outcomes may provide greater precision in predicting OS for subsets of pts with pancreatic cancer. Clinical trial information: NCT02562716.

Association of high gene expression levels of ARF6 with the immune microenvironment and prediction of poor outcomes

3092

Background: ADP-ribosylation factor 6 ( ARF6) is a small GTPase in the RAS superfamily, which regulates membrane trafficking, remodeling and tumor progression. Preclinical study shows that TP53 and KRAS cooperatively activate the ARF6-AMAP1 pathway which serves as a link by which pancreatic driver mutations promote tumor invasion, PD-L1 dynamics and immune evasion properties in pancreatic ductal adenocarcinoma (PDAC). The clinical impact of ARF6 on cancer progression and prognosis remains unclear. Methods: A total of 2,948 PDAC samples were analyzed using next-generation sequencing of RNA (whole transcriptome, NovaSeq) and DNA (NextSeq, 592 genes or NovaSeq, whole exome sequencing) and immunohistochemistry (IHC) (Caris Life Sciences, Phoenix, AZ). QuantiSeq (Finotello 2019, Genome Medicine) was used to quantify immune cell infiltration. Overall survival (OS) was obtained from insurance claims, and Kaplan-Meier estimates were calculated for molecularly defined cohorts. Significance was determined as p values adjusted for multiple correction ( q) of <.05. Results: Median ARF6 expression was higher in metastases (33.69 transcriptions per million) compared to primary/local tumors (27.59, q<.05). Specific metastatic sites showed higher expression than did primary tumors ( q<.05 for liver and p<.05 for skin, bone and lymph nodes). Dividing into quartiles by ARF6 expression (the highest expression quartile, QH; the lowest, QL), KRAS mutations were significantly more prevalent in QH than QL (93.4 vs 87.2%, q<.05), and TP53 mutations had similar trends (81.0% in QH vs 74.7% in QL, p=.0078). The mutation rates of KDM6A, FANCD2 and TFEB amplifications trended higher in QH than QL; the STK11 mutation rate tended to be lower in QH ( p<.05). PD-L1 expression by IHC was significantly higher in QH than QL (20.9 vs 13.1%); immune checkpoint genes by RNA expression: IFNG, IDO1, PDCD1G2, CD274, PDCD1 and PDCD2L were significantly higher in QH than QL (all q<.05). Macrophages, neutrophils, NK cells, fibroblasts and endothelial cells were more abundant in QH than QL (all q<.05); whereas CD4+ and CD8+ T cells were lower in QH ( q<.05), and monocytes had similar trends ( p<.05). High expression of ARF6 was significantly associated with unfavorable outcomes in OS (HR = 1.83, 95% CI [1.51–2.22], p<.0001); the effect on OS was seen when primary (HR = 1.47, [1.06–2.05], p=.02) and metastatic tumors (HR = 0.608, [1.29–2.10], p<.0001) were investigated separately. Conclusions: This is the first report showing that high gene expression of ARF6 in PDAC indicates a different immune profile, is enriched in cancer metastases, and is associated with poor survival. Our results provide the first clinical evidence supporting the ARF6 pathway as a major downstream target of KRAS and TP53 mutations promoting immune evasion, suggesting ARF6 is a novel marker for prognosis and a potential target for immune therapeutic strategies in PDAC.

Globo H expression in metastatic colorectal cancer (CRC)

3527

Background: Globo H is a carbohydrate antigen that is highly expressed on the cell surface of epithelial cancers but not in normal tissue, and has been reported to correlate with poor prognosis. An attractive therapeutic target, Globo H-targeted agents are being tested in early clinical trials (e.g., OBI-833, a Globo H antigen conjugated to a mutated diphtheria toxin with potential antineoplastic activities, and OBI-999, an antibody-drug conjugate (ADC) consisting of a Globo H monoclonal antibody with a synthetic antineoplastic agent). We aim to describe the molecular features associated with Globo H expression in CRC. Methods: A total of 7,604 CRC tumors were tested by Caris Life Sciences (Phoenix, AZ) by NextGen DNA and RNA sequencing. The expression of β3GalT5, FUT-1 and FUT-2 were evaluated as surrogates for Globo H expression as they are the key enzymes in its biosynthesis. An average z-score of the 3 genes (GloboH) and of β3GalT5 (B3) alone were calculated; tumors with top quartile z-scores were considered expression-high (Q4) and bottom quartile, expression-low (Q1). QuantiSEQ was used to assess immune cell infiltration in the tumor microenvironment (TME). Statistical significance was determined using chi-square/Fisher-Exact and adjusted for multiple comparisons (q<0.05). Consensus molecular subtype (CMS) was developed using RNA seq data. Results: When the 3 genes were considered, GloboH-H tumors showed higher prevalence of CMS1 and CMS4 (23.8% vs. 12%; 38.7% vs. 29.4%) and lower prevalence of CMS2 (40% vs. 18.7%) compared to GloboH-L. Similar patterns of CMS distribution were seen for B3 alone. B3-H tumors were significantly more frequently TMB-H (>=10) (11.4% vs. 8.3%), PD-L1 positive (5.7% vs. 3.4%) and MSI-H/dMMR (8.3% vs. 5.5%). Strong positive associations were seen with mutations in BRAF, KRAS, RSPO3 fusion, and cMYC amplification with B3 alone and GloboH (all q<0.05). Anti-tumor CD4+ T cells and NK cells were increased in the TME with increased expression of GloboH and B3 (q<0.05). However, immune suppressive neutrophils and Tregs were also increased. Dendritic cells were negatively associated with B3 expression while endothelial cells and fibroblasts showed a positive association with GloboH and B3. Conclusions: The association with TMB-H, MSI-H, and PD-L1 status suggests that in some tumors Globo H may be a promising target for combination therapy with immune checkpoint inhibition. The association with different cell populations suggests manipulating the cellular balance in the TME as an approach to improve the efficacy of treatment. NK cell checkpoint inhibitors are in clinical trials and might be utilized in high Globo H cancers; treatments inducing DCs in tumors have been shown to enhance responses to BRAF and PD-L1 blockade and might be applicable in the context of Globo H immunotherapy to overcome Treg immune suppression. Anti-Globo H vaccines and ADCs might be particularly effective in BRAF and KRAS-mutant CRC patients.

The Landscape of Alterations in DNA Damage Response Pathways in Colorectal Cancer

PURPOSE

Defective DNA damage response (DDR) is a hallmark of cancer leading to genomic instability and is associated with chemosensitivity. Although the mismatch repair system has been extensively studied, the clinical implications of other mechanisms associated with DDR alterations in patients with colorectal cancer remain unclear. This study aimed to understand DDR pathways alterations and their association with common clinical features in patients with colorectal cancer.

EXPERIMENTAL DESIGN

Next-generation sequencing and whole-transcriptome sequencing were conducted using formalin-fixed paraffin-embedded samples submitted to a commercial Clinical Laboratory Improvement Amendments-certified laboratory. Samples with pathogenic or presumed pathogenic mutations in 29 specific DDR-related genes were considered as DDR-mutant (DDR-MT) and the remaining samples as DDR-wild type (DDR-WT).

RESULTS

Of 9,321 patients with colorectal cancer, 1,290 (13.8%) were DDR-MT. The frequency of DDR-MT was significantly higher in microsatellite instability-high (MSI-H) cases than in microsatellite stable cases (76.4% vs. 9.5%). The DDR-MT genotype was higher in the right-sided, RAS-wild, BRAF-mutant, and CMS1 subgroups. However, these associations were primarily confounded by the distribution of MSI status. Compared with the DDR-WT tumors, the DDR-MT tumors had a higher mutational burden and gene expression levels in the immune-related pathway, which were independent of MSI status.

CONCLUSIONS

We characterized a distinct subgroup of patients with colorectal cancer with tumors harboring mutations in the DDR-related genes. These patients more commonly had MSI-H tumors and exhibited an activated immune signature regardless of their tumor's MSI status. These findings warrant further investigations to develop personalized treatment strategies in this significant subgroup of patients with colorectal cancer.

Molecular characterization of pancreatic cancers as seen in the SLUG gene revealing cancer progression

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Background: The SLUG gene plays an important role in EMT by repressing E-cadherin and promotes metastasis. Previous data suggest that overexpressed SLUG gene in pancreatic cancer (PC) showing a high frequency of metastasis and poor prognosis. As SLUG contribution to characteristics or metastatic features remains elusive, we clarified its functional roles in PC progression. Methods: A total of 2958 pancreatic tumors were analyzed using Whole Transcriptome sequencing, NextGen Sequencing (NGS) (NextSeq, 592 gene panel) or Whole Exome Sequencing (WES) (NovaSeq) (Caris Life Sciences, Phoenix, AZ). Microsatellite instability (MSI) status was tested by fragment analysis, immunohistochemistry (IHC) and NGS. PD-L1 expression was tested by IHC. Tumor mutational burden (TMB) was measured by counting all mutations found per tumor (a universal cutoff point of ≧10 mutations per MB). Immune cell fraction was calculated by quanTIseq (Finotello 2019, Genome Medicine). Results: A total of 1274 primary and 1684 metastatic pancreatic tumors were included for this study. They were divided equally into four classes in each group, according to their SLUG expression levels. Tumors in the highest quartile of SLUG expression (QH) showed significantly higher frequency in peritoneal-retroperitoneal-omentum metastasis (15.0%) compared to the lowest quartile (QL) (4.8%) (p = .0001). Similar trends were seen in the abdomen (6% vs 1%, p = .001) and bone (2.8% vs 0.0%, p = .005). However, liver (55.0% in QH vs 63.1% in QL) and lung (2.8% vs 14.1%) metastasis occurred most frequently in QL and the least frequently in QH (p = .0197 and p = .001, respectively). This data indicated that tumors with high SLUG gene expression levels tend to lead to disseminated metastasis, and with low expression levels, they tend to spread intravascularly. We detected significant differences among genetic mutations in ATM (5.7% in QL vs 1.8% in QH, p < 0.001) and APC (2.9% vs 0.5%, p < 0.001), and Wnt signaling expressions were higher in QL (4.6%) than QH (0.7%) (p < 0.001). Binary TMB-H and MSI-H tumors had higher frequencies in QL (2.7% and 2.1%) compared to QH (0.3% and 0.1%) (p < 0.001 in both). Contrastingly, PD-L1 expression levels were higher in QH (23.4%) compared to QL (11.0%) (p < 0.001) and had a linear relationship with the expression levels. The median values of the population of B cells, M1 and M2 macrophages were significantly higher in QH compared to QL, but those of myeloid dendritic and CD8+T cells conversely decrease as the SLUG expression increases. Conclusions: Our data indicated the SLUG expression level could determine the tumor characteristics in progression, especially the pattern of metastasis in PC, and it could possibly predict the prognosis and/or therapeutic effects. We also showed immune oncologic markers which have some relationships with SLUG expressions. Further investigation is warranted to better understand SLUG gene functions.

GDF15 expression in metastatic colorectal cancer

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Background: Cachexia affects many cancer patients. Growth differentiation factor-15 (GDF15) is a protein that regulates weight and the stress response of cells. The GDF15 gene encodes a ligand of TGF-beta that triggers cachexia and modulates the progression from tumorigenesis to metastasis. Inhibition of GDF15 with an antibody restored muscle mass and fat in animal models. Serum levels rise in proportion to the progression of colon cancer, predict outcome, and have been correlated with CEA. Methods: We retrospectively reviewed 7607 CRC tumors profiled by Caris Life Sciences (Phoenix, AZ) from 2019 to 2020. Profiling included whole transcriptome sequencing (RNA-Seq by NovoSeq). Tumor mutational burden, mismatch repair status, and pathway genomic alterations were evaluated. QuantiSEQ was used to assess immune cell infiltration in the tumor microenvironment. Results: GDF15 expression ranged from 0 to 593 transcripts per million (TPM) with median of 30 (IQR = 15.02). There was no association with age, sex, or primary tumor sidedness. MSI-H/dMMR tumors had higher GDF15 expression (median 37 vs 30, p = 0.0004); TMB > = 17 tumors was seen in 5.9% of bottom quartile (Q1) GDF15 expressors and 8.3% of top quartile (Q4). PDL1 IHC positivity was inversely correlated with GDF15 expression (7.1% in Q1 vs. 2.6% in Q4, p < 0.0001). Genomic alterations associated with higher GDF15 expression (Q4 vs Q1) included genes on TGF-B (SMAD2/4), PI3K (PIK3CA, MTOR), chromatin remodeling (ARID1A, KMT2C), DDR (ATM) and Wnt pathway (APC); those inversely associated included MYC CNA and TP53. Q1 tumors had higher CNA of ERBB2 and FGFR1. Relative neutrophils and NK cells in the TME increased from Q1 to Q4 (p < 0.001). There was a decrease in CD8+ T-cells and Treg cells from Q1 to Q4. Conclusions: GDF15 expression correlates with increased dMMR/MSI-H and TMB, but not with PDL1 expression. Mutations and activated pathways associated with GDF15 expression may explain increased cachexia with more aggressive disease. The association with chromatin remodeling may warrant therapies targeting histone modification and epigenetics. The increase in NK cells but decrease in CD8+ T cells in the TME with increasing GDF15 suggests approaches to treatment. Higher CD8+ lymphocyte counts correlate with PFS with immunotherapy. Anti-PD-L1 therapy reinvigorates the killing function of CD8+ T cells. The decrease in CD8+ T cells and PDL1 positivity with rising GDF15 suggests worse outcome and a lack of response to anti-PDL1 therapy. NK cell checkpoint inhibitors, CARs, and an anti-GFRAL antibody are now in clinical trials and might be utilized in high GDF15 cancers. GDF15 is emerging as a target in the treatment of obesity and cachexia and as a prognostic marker in oncology. Understanding its expression in metastatic colon cancer may reveal which patients could benefit from developing anti-GDF15 targeted therapies against cancer progression.

Microbiomic profiles of bile in patients with benign and malignant pancreaticobiliary disease

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Background: In pancreaticobiliary (PB) cancers, there is a paucity of data on predictive and pathophysiologic role of the biliary microbiome. We analyzed bile collected from patients with benign and malignant PB diseases to identify microbiomic signatures associated with malignancy. Methods: We collected bile samples from consenting patients during routine endoscopic retrograde cholangiopancreatography at the Cleveland Clinic, approved by the Institutional Review Board. DNA was extracted from bile specimens using PowerViral RNA/DNA Isolation kit. Bacterial 16S rRNA gene amplification and library construction were performed according to the 16S Metagenomic Sequencing Library Preparation guide from Illumina. Post-sequencing analysis was done using QIIME (Quantitative Insights Into Microbial Ecology), Bioconductor phyloseq, microbiomeSeq and mixMC packages. Results: Of 46 enrolled patients, 32 had PB cancers including pancreatic (N = 25), cholangiocarcinoma (N = 6), and gallbladder (N = 1). The rest (N = 14) had benign PB diseases including acute and chronic pancreatitis, and gallstones. Using multivariate approach in mixMC to classify Operational Taxonomic Units (OTUs), we found a predominance of genera Dicekeya (p = 0.0002), [ Eubacterium] hallii group (p = 0.0007) , Bacteroides (p = 0.00099) , Faecalibacterium (p = 0.007) , Facklamia (p = 0.013) , Peptococcus (p = 0.013) , Bergeyella (p = 0.0024) , Lachnospira (p = 0.026) , and Lactobacillus (p = 0.025) in bile samples from PB cancers as compared to benign PB diseases. Furthermore, bile samples from patients with pancreatic cancer showed an increased abundance of genera Enterobacter, Parabacteroides, Atopobium, Alloprevotella, Prevotella 7, Acinetobacter, Bergeyella, Clostridium sensu stricto, Lactobacillus, and Rothia; and a decreased abundance of genera Tannerella, Peptococcus, Colinsella, Capnocytophaga, Achromobacter, Ruminococcus 2, Bacteroides, Alistipes, Barnesiella,, Lachnoclostridium, Lautropia, Akkermansia, and Christensenellaceae R-7 group as compared to bile samples from patients with cholangiocarcinoma. Conclusions: Distinct microbiome signatures are associated with benign and malignant PB diseases. There is a difference in the relative abundance of OTUs in bile samples between patients with benign PB diseases vs PB cancers, and between pancreatic cancer vs cholangiocarcinoma. Our findings raise the possibility that either these OTUs have a role in carcinogenesis, or that changes in the microenvironment of benign PB diseases differ from PB cancers leading to distinct separation of the OTU clusters. Further studies to explore and validate our findings are needed.

Immunologic predictors of therapeutic response to neoadjuvant chemotherapy for pancreatic ductal adenocarcinoma (PDA) in SWOG S1505

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Background: A role for the immune system in predicting treatment outcomes in PDA has not been well-studied prospectively, especially in the curative setting. Here, we investigated the capacity of two established chemotherapy regimens to trigger an immune response against PDA when administered as neoadjuvant therapy. Methods: We used available PDA surgical specimens from SWOG S1505 (a randomized phase II trial of perioperative chemotherapy with either mFOLFIRINOX [FFX] or gemcitabine/nab-paclitaxel [GA] for resectable PDA; ASCO 2020 abstr 4504) resected after 3 months of neoadjuvant chemotherapy, and matched untreated controls from the biorepository at the University of Utah. Multiplex immunohistochemistry (IHC) for CD8, CD68, CK19, FOXP3, PDL1, CD3, and Ki67 was performed; regions of interest (ROIs) were transcribed by a central pathologist. ROIs were digitally quantified using custom image analysis algorithms created using Visiopharm Integrator System software to detect and classify cells within superimposed grids for quantification; medians and coefficients of variation (CV) were calculated. Wilcoxon signed-rank test and Cox regression models were used to analyze associations between IHC cell counts and pathologic response (pR) and overall survival (OS), respectively. Results: IHC cell counts varied between treated (Rx) (n = 57; FFX = 34, GA = 23) and control (C) (n = 61) specimens for: CK19 percent area was 7.9 vs 15.6 (p < 0.001); total Ki67/mm2 was 211 vs 400 (p < 0.001); total CD3/mm2 was 376 vs 676 (p < 0.001); Foxp3/mm2 was 81.5 vs 152.8 (p < 0.001); CD8/mm2 was 313 vs 477 (p < 0.001); CD68/mm2 was 507 vs 741 (p = 0.015). PDL1 expression was undetectable in the majority of specimens, both Rx and C. FFX (vs GA) was associated with fewer CK19+Ki67+ cells (459 vs 1026, p = 0.017) but more CD68+ cells (33,241 vs 13,334, p = 0.007) and slightly more CD8+ cells (19,809 vs 14,344, p = 0.049). In all Rx patients, complete/major (n = 19) vs poor/no (n = 36) pR was associated with total CD3/mm2: 461 vs 308 (p = 0.019); the other parameters showed no notable differences. OS showed no remarkable associations with the tested parameters. Conclusions: We have demonstrated: 1) Decreased tumor cells and proliferating cells in Rx vs C samples, as expected. This decrease is more pronounced with FFX compared with GA; 2) Decreased total CD3+ T cells as well as regulatory Foxp3+ T cells in Rx vs C samples, which is unexpected; 3) A reduction in CD68+ myeloid cells in Rx vs C samples, which is expected but more pronounced with GA compared with FFX; 4) Rx samples did not show an increased expression of PDL1, compared with C; and 5) Improved pR was associated with increased T cell infiltrate, pointing toward a possible mechanism. Together, these data support the capacity of neoadjuvant chemotherapy to modulate the immune response to PDA. Therapeutic implications of such changes merit further investigation. Clinical trial information: NCT02562716.

A pilot clinical trial of the cytidine deaminase inhibitor tetrahydrouridine combined with decitabine to target DNMT1 in advanced, chemorefractory pancreatic cancer

DNA methyltransferase 1 (DNMT1) is scientifically validated as a molecular target to treat chemo-resistant pancreatic ductal adenocarcinoma (PDAC). Results of clinical studies of the pyrimidine nucleoside analog decitabine to target DNMT1 in PDAC have, however, disappointed. One reason is high expression in PDAC of the enzyme cytidine deaminase (CDA), which catabolizes decitabine within minutes. We therefore added tetrahydrouridine (THU) to inhibit CDA with decitabine. In this pilot clinical trial, patients with advanced chemorefractory PDAC ingested oral THU ~10 mg/kg/day combined with oral decitabine ~0.2 mg/kg/day, for 5 consecutive days, then 2X/week. We treated 13 patients with extensively metastatic chemo-resistant PDAC, including 8 patients (62%) with ascites: all had received ≥ 1 prior therapies including gemcitabine/nab-paclitaxel in 9 (69%) and FOLFIRINOX in 12 (92%). Median time on THU/decitabine treatment was 35 days (range 4-63). The most frequent treatment-attributable adverse event was anemia (n=5). No deaths were attributed to THU/decitabine. Five patients had clinical progressive disease (PD) prior to week 8. Eight patients had week 8 evaluation scans: 1 had stable disease and 7 PD. Median overall survival was 3.1 months. Decitabine systemic exposure is expected to decrease neutrophil counts; however, neutropenia was unexpectedly mild. To identify reasons for limited systemic decitabine effect, we measured plasma CDA enzyme activity in PDAC patients, and found a > 10-fold increase in those with metastatic vs resectable PDAC. We concluded that CDA activity is increased not just locally but also systemically in metastatic PDAC, suggesting a need for even higher CDA-inhibitor doses than used here.

Abstract 3638: Analysis of the clinical benefit of comprehensive genome profiling derived therapeutic associations in advanced cancer

Modern cancer care has seen an increase in the use of targeted therapies and the number of FDA-approved biomarkers. To take advantage of these options, many have turned to commercially available comprehensive genome profiling (CGP) services, like Foundation Medicine's FoundationOne assay. FoundationOne (FO) offers a list of clinically relevant genomic alterations and biomarkers, as well as a list of clinical trials, on-label and off-label therapies that may benefit the patient, that is, therapeutic associations. We performed a retrospective cohort study to assess the clinical benefit of therapy associations from FO reports.

We collected demographics, therapy records, and clinical outcomes for 1004 patients who had a history of advanced cancer in the Cleveland Clinic system and had received a FO report between 2012 and 2017. FO therapy associations were considered as “applied” if a patient received an order for said therapy for the first time after their report date. We classified patients as follows: No Associated Therapy (NAT) if the patient did not receive any recommendations, Therapy Applied (TA) if at least one associated therapy was ordered after report date, and Therapy Not Applied (TNA) if none of the associated therapies were applied. We evaluated differences in demographic and clinical features among the 3 groups using Chi-squared and Kruskal-Wallis tests where appropriate. We performed survival analysis using univariate and multivariate COX Proportional Hazards regression models, and Log-Rank tests on Kaplan Meier Curves with overall survival (OS) as our metric.

Our cohort demographics were 55% male, 85% white, 92% non-Hispanic, and a median age at report of 60 (IQR: 51-69). The most common diagnoses were Lung Adenocarcinoma (14%), Glioblastoma (8%), Colon Adenocarcinoma (8%), and Breast Cancer NOS (4%). Most of our patients belonged to the TNA class (64%), 21% were NAT, and 15% were TA. There was no statistical significance in the demographic distribution among the therapy classes. In the pan-cancer analysis, we found no statistically significant difference in OS among the therapy groups or any of the adjusted covariates except for metastasis status. Similarly, when evaluating the top cancer diagnoses individually, we found no significant differences in OS.

The data in our study indicates that the application of FO therapy associations is not correlated with a statistically significant difference in OS for advanced cancer patients. This suggests that larger studies should be performed to better understand how CGP services provide clinical benefits to patients, and how we can maximize these benefits in the real-world community setting.

Citation Format: Jean Rene Clemenceau, Sung Hak Lee, Alex Milinovich, Jian Jin, Nathan Pennell, Davendra Sohal, Tae Hyun Hwang. Analysis of the clinical benefit of comprehensive genome profiling derived therapeutic associations in advanced cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3638.