Failure to Undergo Resection Following Neoadjuvant Therapy for Resectable Pancreatic Cancer: A Secondary Analysis of SWOG S1505

BACKGROUND

Neoadjuvant therapy (NT) is increasingly used for patients with pancreatic ductal adenocarcinoma (PDAC), and yet reasons for not undergoing subsequent pancreatectomy are poorly understood. Given the importance of completing multimodality therapy, we investigated factors associated with failure to undergo surgical resection following NT for PDAC.

METHODS

SWOG S1505 was a multicenter phase II randomized trial of preoperative mFOLFIRINOX or gemcitabine/nab-paclitaxel prior to planned pancreatectomy for patients with potentially resectable PDAC. Associations between clinical, demographic, and hospital-level characteristics and receipt of surgical resection were estimated via multiple logistic regression. Differences in overall survival from 18 weeks postrandomization (scheduled time of surgery) according to resection status were assessed via Cox regression models.

RESULTS

Among 102 eligible patients, 73 (71.6%) underwent successful pancreatectomy, whereas 29 (28.4%) did not, primarily because of progression (n=11; 10.8%) or toxicity during NT (n=9; 8.8%). Weight loss during NT (odds ratio [OR], 0.34; 95% CI, 0.11-0.93) and the hospital's city size (small: OR, 0.24 [95% CI, 0.07-0.80] and large: OR, 0.28 [95% CI, 0.10-0.79] compared with midsize) were significantly associated with a lower probability of surgical resection in adjusted models, whereas age, sex, race, body mass index, performance status, insurance type, geographic region, treatment arm, tumor location, chemotherapy delays/modifications, and hospital characteristics were not. Surgical resection following NT was associated with improved overall survival (median, 23.8 vs 10.8 months; P<.01) even after adjusting for grade 3-5 adverse events during NT, performance status, and body mass index (hazard ratio, 0.55; 95% CI, 0.32-0.95).

CONCLUSIONS

Failure to undergo resection following NT was relatively common among patients with potentially resectable PDAC and associated with worse survival. Although few predictive factors were identified in this secondary analysis of the SWOG S1505 randomized trial, further research must focus on risk factors for severe toxicities during NT that preclude surgical resection so that patient-centered interventions can be delivered or alternate treatment sequencing can be recommended.

Phase I study of peposertib and avelumab with or without palliative radiotherapy in patients with advanced solid tumors

INTRODUCTION

We report results from a phase I, three-part, dose-escalation study of peposertib, a DNA-dependent protein kinase inhibitor, in combination with avelumab, an immune checkpoint inhibitor, with or without radiotherapy in patients with advanced solid tumors.

MATERIALS AND METHODS

Peposertib 100-400 mg twice daily (b.i.d.) or 100-250 mg once daily (q.d.) was administered in combination with avelumab 800 mg every 2 weeks in Part A or avelumab plus radiotherapy (3 Gy/fraction × 10 days) in Part B. Part FE assessed the effect of food on the pharmacokinetics of peposertib plus avelumab. The primary endpoint in Parts A and B was dose-limiting toxicity (DLT). Secondary endpoints were safety, best overall response per RECIST version 1.1, and pharmacokinetics. The recommended phase II dose (RP2D) and maximum tolerated dose (MTD) were determined in Parts A and B.

RESULTS

In Part A, peposertib doses administered were 100 mg (n = 4), 200 mg (n = 11), 250 mg (n = 4), 300 mg (n = 6), and 400 mg (n = 4) b.i.d. Of DLT-evaluable patients, one each had DLT at the 250-mg and 300-mg dose levels and three had DLT at the 400-mg b.i.d. dose level. In Part B, peposertib doses administered were 100 mg (n = 3), 150 mg (n = 3), 200 mg (n = 4), and 250 mg (n = 9) q.d.; no DLT was reported in evaluable patients. Peposertib 200 mg b.i.d. plus avelumab and peposertib 250 mg q.d. plus avelumab and radiotherapy were declared as the RP2D/MTD. No objective responses were observed in Part A or B; one patient had a partial response in Part FE. Peposertib exposure was generally dose proportional.

CONCLUSIONS

Peposertib doses up to 200 mg b.i.d. in combination with avelumab and up to 250 mg q.d. in combination with avelumab and radiotherapy were tolerable in patients with advanced solid tumors; however, antitumor activity was limited.

CLINICALTRIALS

GOV IDENTIFIER

NCT03724890.

Current state of the art: immunotherapy in esophageal cancer and gastroesophageal junction cancer

Esophageal cancers have a high mortality rate and limited treatment options especially in the advanced/metastatic setting. Squamous cell carcinoma (SCC) and adenocarcinoma are two distinct types of esophageal cancer. Esophageal SCC is more common in nonindustrialized countries with risk factors including smoking, alcohol use, and achalasia. Adenocarcinoma is the predominant esophageal cancer in developed nations, and risk factors include chronic gastroesophageal reflux disease, obesity, and smoking. Chemotherapy has been the mainstay of therapy for decades until immunotherapy made its debut in the past few years. Immune checkpoint inhibitors have been tested in many studies now and are becoming an essential component of esophageal cancer treatment. Monoclonal antibodies that selectively inhibit programmed cell death-1 (PD-1) activity such as pembrolizumab and nivolumab, have become standard of care in the treatment of esophageal cancer. Several other anti-PD-1 antibodies like camrelizumab, toripalimab, sintilimab, trislelizumab are under investigation in different stages of clinical trials. Here we provide a comprehensive review of extant literature as well as ongoing trials with various combinations of chemotherapy or other targeted therapy with a focus on different histological subgroups of esophageal cancer and in different clinical settings.

Feasibility Trial of Intensity Modulated Proton Therapy to Reduce Toxicity in Anal Cancer Patients

PURPOSE

The purpose of this trial was to assess the patient and physician-reported toxicity in anal cancer patients undergoing definitive chemoradiation with intensity-modulated proton therapy (IMPT).

METHODS

Patients with stage II and III anal cancer were treated with IMPT. All patients received 2 cycles of 5-fluorouracil and mitomycin concurrently with radiation. Toxicity was assessed at baseline, weekly during chemoradiation, and in follow-up using physician-graded common terminology criteria for adverse events (CTCAE) v 4.0 and PRO-CTCAE. The primary endpoint was to define point estimates and 95% CI for acute ≥ grade 2/3 gastrointestinal (GI), genitourinary (GU), dermatologic, and hematologic toxicity. The proportion of PRO-CTCAE questions scored ≥3 for each domain was compared with the baselinse. The proportion of ≥ grade 2 and ≥ grade 3 toxicities were compared with historic intensity-modulated radiotherapy patients treated on RTOG 0529.

RESULTS

Fourteen patients were enrolled from 2017 to 2020. Rates of physician-reported GI, GU, dermatologic, and hematologic toxicity were not significantly different between patients treated with IMPT compared with patients treated with intensity-modulated radiotherapy. Rates of patient-reported dermatologic and GU toxicity were low at baseline with a peak at week 6 (91% and 58% PRO-CTCAE items ≥ grade 3, respectively) and normalization to baseline 3 months after IMPT. In contrast, the proportion of high-grade PRO-CTCAE GI scores was 40% at baseline, which persisted through 1-year posttreatment.

CONCLUSIONS

Clinician-reported toxicity was not improved with IMPT in the context of this underpowered trial. High-grade GI symptoms persisted for 12 months and were similar to baseline. Additional measures are needed to minimize acute and chronic toxicity related to chemoradiation.

Analysis of the fecal metagenome in long-term survivors of pancreas cancer

BACKGROUND

The 5-year overall survival of pancreas adenocarcinoma (PCa) remains less than 10%. Clinical and tumor genomic characteristics have not differentiated PCa long-term survivors (LTSs) from unselected patients. Preclinical studies using fecal transplant experiments from LTSs of PCa have revealed delayed tumor growth through unknown mechanisms involving the fecal microbiota. However, features of the fecal microbiome in patients with long-term survival are not well described.

METHODS

In this cross-sectional study, comprehensive shotgun metagenomics was performed on stool from PCa patients with long-term survival (n = 16). LTS was defined as >4 years from pancreatectomy and all therapy without recurrence. LTSs were compared to control patients with PCa who completed pancreatectomy and chemotherapy (n = 8). Stool was sequenced using an Illumina NextSeq500. Statistical analyses were performed in R with MicrobiomeSeq and Phyloseq for comparison of LTSs and controls.

RESULTS

All patients underwent pancreatectomy and chemotherapy before sample donation. The median time from pancreatectomy of 6 years (4-14 years) for LTSs without evidence of disease compared to a median disease-free survival of 1.8 years from pancreatectomy in the control group. No differences were observed in overall microbial diversity for LTSs and controls using Shannon/Simpson indexes. Significant enrichment of species relative abundance was observed in LTSs for the Ruminococacceae family specifically Faecalibacterium prausnitzii species as well as Akkermansia muciniphila species.

CONCLUSIONS

Stool from patients cured from PCa has more relative abundance of Faecalibacterium prausnitzii and Akkermansia muciniphila. Additional studies are needed to explore potential mechanisms by which the fecal microbiota may influence survival in PCa.

PLAIN LANGUAGE SUMMARY

Although pancreatic cancer treatments have improved, the number of long-term survivors has remained stagnant with a 5-year overall survival estimate of 9%. Emerging evidence suggests that microbes within the gastrointestinal tract can influence cancer response through activation of the immune system. In this study, we profiled the stool microbiome in long-term survivors of pancreas cancer and controls. Several enriched species previously associated with enhanced tumor immune response were observed including Faecalibacterium prausnitzii and Akkermansia muciniphila. These findings warrant additional study assessing mechanisms by which the fecal microbiota may enhance pancreatic cancer immune response.

Immune checkpoint inhibitors in liver transplant: a case series

BACKGROUND

Immune checkpoint inhibitors (ICIs) in the setting of liver transplant (LT) pose a risk of rejection and hold unclear benefit in both the neoadjuvant (pre-transplant) and post-transplant salvage setting. In the pre-transplant setting, neoadjuvant ICIs may serve as a bridge to LT by downstaging disease burden to fit within transplant criteria. Outcomes in this setting include patients who had successful transplants without complications to patients who suffered severe complications, including fatal hepatic necrosis and graft failure requiring re-transplant. Some authors suggest having a period of three months between checkpoint inhibition and transplant may help mitigate adverse effects. In the post-LT setting, there are few treatment options if there is a recurrence of disease, which forces treatment teams to reconsider checkpoint inhibitors. Again, a longer period of time between transplant and checkpoint inhibition may reduce risk of rejection. Case reports of patients treated with ICIs post-transplant utilized either nivolumab or pembrolizumab. As combination atezolizumab/bevacizumab is a relatively new treatment option for unresectable hepatocellular carcinoma (HCC), there are only three reported cases using this combination in the post-LT setting. While there were no cases of rejection, all three cases had progression of disease. As immunotherapy joins transplantation as a mainstay of treatment for HCC, it remains unclear how to best navigate when the treatment course involves both immune activation and immunosuppression.

CASE DESCRIPTION

Patients who had an LT and were treated with ICIs (pre or post LT) at the University of Cincinnati were included in this retrospective chart review.

CONCLUSIONS

Fatal rejection remains a significant risk even 4 years after LT. Neoadjuvant ICIs also pose a risk for acute cellular rejection; however, this may not always be clinically significant. Graft versus host disease (GVHD) may be an additional, previously unreported risk of ICIs in the setting of LT. Prospective studies are needed to understand benefits and risks of checkpoint inhibitors in the LT setting.

Development of an artificial intelligence-derived histologic signature associated with adjuvant gemcitabine treatment outcomes in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has been left behind in the evolution of personalized medicine. Predictive markers of response to therapy are lacking in PDAC despite various histological and transcriptional classification schemes. We report an artificial intelligence (AI) approach to histologic feature examination that extracts a signature predictive of disease-specific survival (DSS) in patients with PDAC receiving adjuvant gemcitabine. We demonstrate that this AI-generated histologic signature is associated with outcomes following adjuvant gemcitabine, while three previously developed transcriptomic classification systems are not (n = 47). We externally validate this signature in an independent cohort of patients treated with adjuvant gemcitabine (n = 46). Finally, we demonstrate that the signature does not stratify survival outcomes in a third cohort of untreated patients (n = 161), suggesting that the signature is specifically predictive of treatment-related outcomes but is not generally prognostic. This imaging analysis pipeline has promise in the development of actionable markers in other clinical settings where few biomarkers currently exist.

Impact of patient characteristics and treatment patterns on outcomes in potentially resectable pancreatic cancer (PC)

681

Background: Treatment of PC remains a challenge, with surgery being the mainstay of potentially curative therapy. Even after surgical resection, however, many patients experience recurrence. There has been a shift toward treating PC as a systemic disease from diagnosis with neoadjuvant chemotherapy (nCT) or chemoradiation (nCRT). This study examines characteristics of real-world patients who were deemed to have resectable (R) or borderline resectable (BR) disease, and how they relate to overall survival (OS). Methods: This is a retrospective analysis of patients in an academic health system who presented for initiation of treatment for PC staged as R or BR. Descriptive data on patient characteristics, performance status (PS), laboratory values, neoadjuvant therapies, recurrence, and mortality were obtained. OS was evaluated using Kaplan-Meier analysis and log-rank tests. Two-sided p-values were calculated. Results: From electronic records at the University of Cincinnati, 129 patients were identified. Median age was 66 with baseline ECOG PS of mostly 0 (86, 67%) or 1 (40, 31%). Primary tumor site was most commonly head of pancreas (104, 81%). Of 129, 55 (43%) patients received surgery upfront; the rest received neoadjuvant therapy (39 nCRT, 35 nCT) with gemcitabine (68%) or 5-fluorouracil (32%) containing regimens. Of those receiving nCRT/nCT, 36 (49%) went on to resection; the rest experienced progression (27, 36%) or toxicities (11, 15%) including death. Of 129, 92 (71%) have died, with median OS of 20.1 months (95% CI 16.4 - 25.0) for the full cohort. On adjusted multivariable analysis, the following were associated with worse OS: failure to undergo resection (HR 5.65, 95% CI 3.17 - 10.09, p<0.0001); receiving <3 cycles nCT (HR 3.00, 95% CI 1.38 - 6.53, p=0.006); baseline CA 19-9 >100 (HR 2.73, 95% CI 1.52 - 4.90, p=0.001); BR disease (HR 2.20, 95% CI 1.27 – 3.81, p=0.005); not receiving RT (HR 1.91, 95% CI 1.04 - 3.53, p=0.038). Regimen choice was not associated with OS. Conclusions: In this real-world PC dataset, surgical resection remains the mainstay of curative therapy. Inadequate nCRT/nCT lead to suboptimal outcomes, likely reflecting patient physiology and disease biology effects. Future trials should focus on maximizing neoadjuvant therapy with the goal of resection.[Table: see text]

Analysis of HLA gene expression in patients with dMMR/MSI-H colorectal carcinoma resistant to immune checkpoint inhibitors

202

Background: Large studies have identified immune checkpoint inhibitors (ICI) as an effective therapy for deficient mismatch repair/microsatellite instability high (dMMR/MSI-H) colorectal cancer (CRC). However, a subset of dMMR/MSI-H CRC patients exist that do not benefit from ICI and show rapid cancer progression within the first 6 months of therapy. Genetic alterations of the host immune system, including loss of β2M and single copy loss of HLA molecules, can contribute to innate resistance to ICI. In this study, we sought to analyze the role of expression of HLA genes and β2M as determinants of innate resistance to ICI by analyzing an extensive clinico-genomic database. Methods: Next-generation sequencing (NGS) of DNA (592-gene or whole exome) and RNA (whole transcriptome) was performed on CRC patient samples (n = 24,394) submitted to a CLIA-certified laboratory (Caris Life Sciences, Phoenix, AZ). dMMR/MSI-H was assessed by IHC/NGS. PD-L1 expression was tested by IHC (SP142; positive (+): ≥2+, ≥%5). Real world overall survival and treatment data were obtained from insurance claims data. Time-To-Next-treatment (TTNT) was calculated from start of ICI monotherapy to the start of next therapy, or death. Kaplan-Meier estimates were used for comparison. A composite signature of MHC II gene expression was tested for molecular associations. Immune cell infiltration was estimated by RNA deconvolution using quanTIseq. Statistical significance was determined using Fisher’s Exact/Mann Whitney/X2 tests. Results: We identified 1549 patients with dMMR/MSI-H CRC; 242 patients of these had received pembrolizumab or nivolumab. Using TTNT as a proxy for progression on treatment, we divided the patients into two cohorts: >180 days TTNT and <180 days TTNT. Following manual curation of the cases by two oncologists and limiting the patients to those who had received ≥ 2 doses of either ICI and at least 180 days of recorded follow up, we generated cohorts of 77 patients (>180 days TTNT; good responders) and 34 patients (<180 days TTNT; poor responders). High expression of HLA genes (HLA-DRB1, HLA-B, HLA-DQB1, HLA-DPB1, HLA-DPA1- p<0.02; fold change 2.1-3) was found in the good responder group. No β2M alterations were detected in either subgroup. After dividing the entire cohort into quartiles, patients in the highest quartile of expression for either CD74, HLA-DQA1, HLA-DQB1, HLA-DPB1 or HLA-DRB1 had improved survival when compared to lower expressors (p< 0.05). High MHC II signature expression was associated with an increased rate of PD-L1+ (34 vs 8%, p<0.0001) and infiltration of M1 macrophages (9.1 vs 4.9%, p<0.0001). Conclusions: We identify elevated expression of HLA genes involved in formation of the MHC-II complex as a potential biomarker of improved response to immunotherapy that could, if further validated, optimize patient selection for ICI in CRC.

Durvalumab and tremelimumab for hepatocellular carcinoma in patients listed for a liver transplant

TPS638

Background: Hepatocellular carcinoma (HCC) is an aggressive malignancy, developing most often in the setting of liver cirrhosis (Sohal et al Current Oncol Rep 2011; Gordan et al JCO 2020). For advanced disease, immunotherapy has now become standard of care – a combination of atezolizumab and bevacizumab has shown the best overall survival outcome so far (Finn et al NEJM 2020). For earlier stage disease, however, there is no systemic therapy standard. The best treatment for HCC in the setting of cirrhosis is a liver transplant allowing potential cure for both the cancer and cirrhosis. Nonetheless, 25-35% of patients fail to reach liver transplant because of disease progression while waiting for a transplant (Sinha et al, Hepatology 2019) and approximately 15% experience HCC recurrence after transplant (Mehta et al, Transplantation 2020). Taken together, this constitutes a large subset of this patient population who cannot achieve a cure. Given the success of immunotherapy in the advanced setting, it is imperative to study this in the pre-transplant setting, to improve the outcomes cited above. However, there is a theoretical risk of graft rejection with immunostimulatory treatment. Methods: This is a single-arm, open-label, Phase II, multicenter study designed to evaluate the safety and efficacy of durvalumab and tremelimumab for the treatment of HCC patients who have cirrhosis or portal hypertension and are eligible for listing for a liver transplant. Eligibility requirements include adult patients with HCC within UCSF criteria, a Child-Pugh score of up to 7, and ECOG PS of 0 or 1. Treatment includes an immunotherapy combination of 1 dose of tremelimumab and 5 doses of durvalumab for up to 4 months. After a minimum 28-day gap following the final durvalumab dose, patients undergo locoregional therapy per institutional standards. After a minimum 72-day gap from the end of immunotherapy, patients undergo liver transplant. Primary outcome is a binary endpoint, and it will be assessed in patients undergoing liver transplant. Historically, 10-20% of patients are expected to experience acute cellular rejection within 30 days of transplant. We propose that an observed proportion of 20% treatment failure will be a clear indicator of safety in this pilot study, whereas an observed proportion of 50% failure will be a clear indicator of failure. Using these guardrails, with at least 20 patients going to transplant, we will have 80.6% power to demonstrate a failure proportion of 20% (4 patients experiencing failure) versus a null of 50% (10 patients experiencing failure), with a one-sided alpha of 0.05. With 25 patients going to transplant, the power will increase to 86% (other parameters being the same). Correlative studies include tumor molecular profiling, peripheral blood immunophenotyping, and circulating tumor DNA for early recurrence detection. Clinical trial information: NCT05027425 .

An adaptive approach to neoadjuvant therapy to maximize resection rates for pancreatic adenocarcinoma: A phase II trial

TPS771

Background: Curative treatment for potentially resectable (resectable or borderline resectable) pancreatic adenocarcinoma, despite recent advances, leads to only suboptimal outcomes. Recent US national cooperative group trials have demonstrated the safety and feasibility of neoadjuvant chemotherapy (PMID 33475684, PMID 35834226), and also show that the two frontline regimens, FOLFIRINOX (5-fluorouracil, irinotecan, oxaliplatin) and gemcitabine/nab-paclitaxel (GnP), are comparable in this setting. Finally, ability to undergo resection remains the key driver of cure. Therefore, an approach that selects chemotherapy based on early response assessment, to maximize the probability of resection, is likely to improve curative outcomes. Methods: This is a phase II study intended to maximize the probability of surgical resection for pancreatic cancer. Key eligibility requirements include adult patients with a confirmed histopathologic diagnosis of pancreatic carcinoma or adenocarcinoma, an ECOG PS ≤ 1, resectable or borderline resectable disease by central radiology review, no prior therapy for index pancreatic cancer, and adequate bone marrow, liver and kidney function. Treatment includes 4 doses (~ 2 months total treatment time) of FOLFIRINOX (“Chemo1”). After a re-evaluation, using radiologic response, CA19.9 response, and chemotherapy toxicity, patients will either continue with “Chemo1” for another 4 cycles (8 doses) or switch to GnP (“Chemo2”) which will be administered for 4 cycles (12 doses, for ~4 month total treatment time), followed by surgical resection. Primary outcome will measure the proportion of patients undergoing surgical resection using historical dated compared to 32 patients in a current study with a time frame of 16 months. Using historical data, the expected proportion of patients undergoing resection is ~60%. The goal of this study is to increase this to 80% or higher. With a one-sided of 0.05 and power of 80%, 32 patients will be needed to demonstrate this difference. Key translational correlatives will include serial circulating tumor DNA assessment and extensive tumor molecular profiling. Clinical trial information: NCT04594772 .

Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: ASCO Endorsement of College of American Pathologists Guideline

PURPOSE

The College of American Pathologists (CAP) has developed a guideline on testing for mismatch repair (MMR) and microsatellite instability (MSI) for patients considered for immune checkpoint inhibitor therapy. ASCO has a policy and set of procedures for endorsing clinical practice guidelines that have been developed by other professional organizations.

METHODS

The CAP guideline was reviewed for developmental rigor by methodologists. An ASCO Endorsement Panel subsequently reviewed the content and the recommendations.

RESULTS

The ASCO Endorsement Panel determined that the recommendations from the CAP guideline, published on August 3, 2022, are clear, thorough, and based on the most relevant scientific evidence. ASCO endorses Mismatch Repair and Microsatellite Instability Testing for Immune Checkpoint Inhibitor Therapy: Guideline From the College of American Pathologists in Collaboration With the Association for Molecular Pathology and Fight Colorectal Cancer.

RECOMMENDATIONS

Within the guideline, MMR immunohistochemistry (IHC), MSI polymerase chain reaction, and MSI next-generation sequencing are all recommended testing options for colorectal cancer, MMR-IHC and MSI-polymerase chain reaction for gastroesophageal and small bowel cancer, and only MMR-IHC for endometrial cancer. No recommendation in favor of any testing method over another could be made for any other cancer. Tumor mutational burden was not recommended as a surrogate for DNA MMR deficiency. If MMR deficiency consistent with Lynch syndrome is detected, it should be communicated to the treating physician.Additional information is available at www.asco.org/molecular-testing-and-biomarkers-guidelines.

Radiation therapy in borderline resectable pancreatic cancer: A review

BACKGROUND

Borderline resectable pancreatic cancer constitutes a complex clinical entity, presenting the clinician with a locally aggressive disease that has a proclivity for distant spread. The benefits of radiation therapy, such as improved local control and improved survival, have been questioned. In this review we seek to summarize the existing evidence on radiation therapy in borderline resectable pancreatic cancer and highlight future areas of research.

METHODS

A comprehensive review of PubMed for clinical studies reporting outcomes in borderline resectable pancreatic cancer was performed in June 2021, with an emphasis placed on prospective studies.

RESULTS

Radiologic "downstaging" in borderline resectable pancreatic cancer is a rare event, although some evidence shows increased clinical response to neoadjuvant chemotherapy over radiation therapy. Margin status seems to be equivalent between regimens that use neoadjuvant chemotherapy alone and regimens that include neoadjuvant radiation therapy. Local control in borderline resectable pancreatic cancer is likely improved with radiation therapy; however, the benefit of improved local control in a disease marked by systemic failure has been questioned. Although some studies have shown improved survival with radiation therapy, differences in the delivery and tolerance of chemotherapy between the neoadjuvant and adjuvant setting confound these results. When the evidence is evaluated as a whole, there is no clear survival benefit of radiation therapy in borderline resectable pancreatic cancer.

CONCLUSION

Once considered a staple of therapy, the role of radiation therapy in borderline resectable pancreatic cancer is evolving as systemic therapy regimens continues to improve. Increased clinical understanding of disease phenotype and response are needed to accurately tailor therapy for individual patients and to improve outcomes in this complex patient population.

Cytoreductive Surgery and Hyperthermic Intraperitoneal Chemotherapy for Colorectal Peritoneal Metastases: A Summary of Key Clinical Trials

The peritoneal cavity is a common site of metastatic spread from colorectal cancer (CRC). Patients with peritoneal metastases (PM) often have aggressive underlying tumor biology and poor survival. While only a minority of patients with CRC have potentially resectable disease, the high overall incidence of CRC makes management of PM a common clinical problem. In this population, cytoreductive surgery (CRS)-hyperthermic intraperitoneal chemotherapy (HIPEC) is the only effective therapy for appropriately selected patients. In this narrative review, we summarize the existing literature on CRS-HIPEC in colorectal PM. Recent prospective clinical trials have shown conflicting evidence regarding the benefit of HIPEC perfusion in addition to CRS. Current strategies to prevent PM in those at high-risk have been shown to be ineffective. Herein we will provide a framework for clinicians to understand and apply these data to treat this complex disease presentation.

Molecular Characterization of KRAS Wild-type Tumors in Patients with Pancreatic Adenocarcinoma

PURPOSE

KRAS mutation (MT) is a major oncogenic driver in pancreatic ductal adenocarcinoma (PDAC). A small subset of PDACs harbor KRAS wild-type (WT). We aim to characterize the molecular profiles of KRAS WT PDAC to uncover new pathogenic drivers and offer targeted treatments.

EXPERIMENTAL DESIGN

Tumor tissue obtained from surgical or biopsy material was subjected to next-generation DNA/RNA sequencing, microsatellite instability (MSI) and mismatch repair status determination.

RESULTS

Of the 2,483 patients (male 53.7%, median age 66 years) studied, 266 tumors (10.7%) were KRAS WT. The most frequently mutated gene in KRAS WT PDAC was TP53 (44.5%), followed by BRAF (13.0%). Multiple mutations within the DNA-damage repair (BRCA2, ATM, BAP1, RAD50, FANCE, PALB2), chromatin remodeling (ARID1A, PBRM1, ARID2, KMT2D, KMT2C, SMARCA4, SETD2), and cell-cycle control pathways (CDKN2A, CCND1, CCNE1) were detected frequently. There was no statistically significant difference in PD-L1 expression between KRAS WT (15.8%) and MT (17%) tumors. However, KRAS WT PDAC were more likely to be MSI-high (4.7% vs. 0.7%; P < 0.05), tumor mutational burden-high (4.5% vs. 1%; P < 0.05), and exhibit increased infiltration of CD8+ T cells, natural killer cells, and myeloid dendritic cells. KRAS WT PDACs exhibited gene fusions of BRAF (6.6%), FGFR2 (5.2%), ALK (2.6%), RET (1.3%), and NRG1 (1.3%), as well as amplification of FGF3 (3%), ERBB2 (2.2%), FGFR3 (1.8%), NTRK (1.8%), and MET (1.3%). Real-world evidence reveals a survival advantage of KRAS WT patients in overall cohorts as well as in patients treated with gemcitabine/nab-paclitaxel or 5-FU/oxaliplatin.

CONCLUSIONS

KRAS WT PDAC represents 10.7% of PDAC and is enriched with targetable alterations, including immuno-oncologic markers. Identification of KRAS WT patients in clinical practice may expand therapeutic options in a clinically meaningful manner.

The tumor microenvironment and immune infiltration landscape of KRAS mutant pancreatic ductal adenocarcinomas (PDAC) compared to colorectal adenocarcinomas (CRC)

4142

Background: The composition of the tumor microenvironment (TME) in PDACs is more heavily driven by mutant (mt) KRAS than any other cancer. How genomic alterations of PDAC including KRAS status affect the immune cell (IC) landscape remains unclear. Thus, we characterized IC types and the prevalence of immuno-oncologic (IO) biomarkers in PDAC by genomic and transcriptomic analysis, and investigated associations of mt KRAS with IC estimates in the TME. Our findings were compared to our previous study in CRC. Methods: A total of 4,142 PDAC and 3,727 CRC with KRAS- mts were analyzed using next-generation DNA sequencing (NextSeq, 592 gene panel or NovaSeq, WES), IHC, and whole transcriptome RNA sequencing (NovaSeq) (Caris Life Sciences, Phoenix, AZ). MSI/MMR was tested by FA, IHC and NGS. TMB-H was classified based on a cut-off of >10 mutations per MB. ICs were estimated by QuantiSeq (Finotello 2019, Genome Medicine) or MCP counter (Betcht 2016, Genome Biology). Significance was determined by X2 and Fisher-Exact and p-adjusted for multiple comparisons (q<0.05). Results: Mutant KRAS was seen in 81% of PDAC and in 48% of CRC. The most common variant was G12D, comprising 43% and 32% of all PDAC and CRC KRAS variants, respectively. The therapeutically actionable KRAS G12C variant comprises 2% and 7% of PDAC and CRC in this cohort, respectively. In PDAC, KRAS mt was associated with lower prevalence of MSI-H/dMMR than KRAS-wildtype (wt); 0.9% vs 1.9%, p=0.027). PDL1 expression was significantly lower in KRAS wt (12%) compared to G12D (19%) and G13X (33%), similar to previous observations in CRC. However, when considering TMB, in PDAC, G12D (1%), G12V (1%) and Q61 (1%) mutations had significantly lower TMB-H than RAS wt tumors (4%); in contradiction to CRC. The immune cell environment of KRAS mt PDAC showed significantly higher infiltration with M1 macrophages and cancer-associated fibroblasts (CAFs), as well as lower M2 macrophages, CD4+ & CD8+ T cells, T-reg, NK, myeloid dendritic and endothelial cells compared to KRAS wt. In CRC, a similar pattern was observed but more pronounced in PDAC. Immune-regulatory markers, were among multiple genes downregulated in KRAS-mt PDAC, including CTLA-4 and LAG3. Overall changes were most pronounced in cases harboring KRAS G12D, G12V, Q61, and rare KRAS variants. Conclusions: The TME of KRAS mt PDAC shows IC patterns similar to KRAS mt CRC. Actionable IO-targets, such as PDL1, are enriched in tumors harboring specific variants of KRAS mt PDAC including the targetable G12C variant. If G12D becomes druggable, it could be targetable in 35% patients with PDAC or 15% in CRC. These results demonstrate that the TME of PDAC and CRC shows immune-cold features. Tailored immunotherapeutic strategies would have to overcome these barriers in KRAS mt PDAC and CRC, possibly in combination with molecularly targeted treatment strategies.

Fecal metagenome analysis in long-term survivors (LTS) of pancreas cancer

e16298

Background: Despite improvements in median survival in pancreas adenocarcinoma (PCa), the 5 year overall survival remains less than 10%. Clinical and tumor genomic characteristics have not differentiated PCa long term survivors (LTS) from unselected patients, however specimens in LTS show enhanced tumor immune response. In preclinical studies, fecal transplant experiments from LTS of PCa reveal delayed tumor growth through unknown mechanisms involving the fecal microbiota (Riquelme Cell 2019). However, features of the fecal microbiome in patients with LTS are unknown. Methods: In this cross-sectional study, comprehensive shotgun metagenomics were performed on stool from PCa patients with LTS (n = 16). LTS was defined as > 4 years from pancreatectomy and all therapy without evidence of recurrence. LTS were compared to control patients with PCa who completed pancreatectomy and chemotherapy (n = 6). Stool was sequenced using an Illumina NextSeq500. Raw reads were processed with Kneaddata for trimming, Kracken2 for taxonomic profiling, Bracken for abundance estimation, and Humann3 for metabolic pathway analyses. Statistical analyses were performed in R with MicrobiomeSeq and Phyloseq for comparison of LTS and controls. Results: At diagnosis, the median age of LTS was 60 with a median time from pancreatectomy of 6 years (4-14 years) at donation. The median age of control patients was 65 with a median disease-free survival of 17 months from pancreatectomy. All patients underwent pancreatectomy and chemotherapy prior to sample donation. No material differences were observed in overall microbial diversity for LTS and controls using Shannon/Simpson indexes. The overall composition of bacteria, eukaryotes, viruses and archaea were similar in LTS relative to controls. Lefse analyses revealed significant enrichment of species relative abundance in LTS for the Ruminococacceae family and the Faecalobacterium genus including the Faecalobacterium prausnitzii species. Enriched species in control patients included Clostridium perfringes. Metabolic pathway analyses of the fecal metagenome of LTS revealed several gene families enriched in Faecalobacterium prausnitzii responsible for starch degradation, ribonucleotide biosynthesis, and thiamin degradation as well gene products from Akermannsia mucinophilia representing unknown pathways. Conclusions: Stool from patients cured from PCa share unique microbial features relative to control populations including enrichment of species in the Faecalobacterium genus and Ruminococacceae family . Interestingly, similar species enrichments are observed in metastatic melanoma patients who respond to PD-1 inhibition (Gopalakrishnan Science 2017). Additional studies are needed to explore underlying immune mediated mechanisms in which the fecal microbiota may influence long term survival in PCa.

Impact of somatic SWI/SNF alterations on the genomic landscape of pancreatic ductal adenocarcinoma and response to PARP and immune checkpoint inhibitor therapy

e16289

Background: The SWI/SNF (SWItch/Sucrose Non-Fermentable) chromatin remodeling complex is an adenosine triphosphate (ATP)-dependent group of proteins that controls the accessibility of transcription factors to DNA and is a dynamic epigenetic regulator of gene expression. This system is deranged in about 14% of pancreatic ductal adenocarcinoma (PDAC) patients (pts). A recent report suggested that SWI/SNF alterations are associated with response to immune checkpoint inhibitors (ICIs). Herein, we investigate the relationship between SWI/SNF alterations and genomic instability, prognosis and response to PARP inhibitors and ICIs. Methods: Tumor molecular profiling was performed on PDAC FFPE samples by NextGen Sequencing on DNA (592 genes or WES) and RNA (WTS) at Caris Life Sciences (Phoenix, AZ). MSI/MMR status was determined by IHC, NGS and fragment analysis. Tumor mutational burden high (TMB-H) was determined by a cutoff of 10mut/MB, PD-L1 was tested by IHC (SP142) with a cutoff of 2+, 5%. SWI/SNF mutant tumors (MT) were compared to wild-type (WT), and significance was determined by X2 or Fisher-Exact and p adjusted for multiple comparisons (q) of < 0.05 (Benjamini-Hochberg correction). Real-world overall survival was obtained from insurance claims data and calculated from tissue collection to last contact; time on treatment (TOT) was calculated from treatment start to finish and compared by the Kaplan-Meier test. Results: Among 5075 PDAC tumors, 311 (6.1%) harbored SWI/SNF alterations (186 ARID1A-mutant, 60 PBRM1, 65 SMARCA4 and 12 SMARCB1). The proportion with SWI/SNF alterations in MSI-H tumors (23/53 or 43%) was higher than MSS (287/4922 or 5.8%, p < 0.001). Since MSI-H PDAC have distinct genomic behavior compared to MSS, MSS tumors were analyzed separately. TMB-H (8.3% vs. 1.2%) and PD-L1-H (23% vs. 15%) were more prevalent in MT than WT (q < 0.05) but not different in MSS tumors (TMB-H: 2.9% vs. 0.6%, q = 0.09; PD-L1: 21.4% vs. 15.4%, q = 0.3). Among the 2268 WES-tested tumors, gLOH-high was not different in MT vs WT (9% vs. 12%, q = 1) in all or in MSS tumors (9.7% vs 11.9%, q = 1). Among the 3728 pts with outcome data, MT pts had worse prognosis (HR = 0.78, 95% CI [0.70-0.87], p < 0.00001), similarly in MSS cohort (HR = 0.734, [ 0.66-0.82], p < 0.00001). Among 50 PARPi-treated pts, no TOT difference was seen between MT vs WT (HR = 0.913, [0.309-2.701], p = 0.9), similarly in MSS pts (HR = 1.104 [0.426–2.86], p = 0.9). In the 38 ICI-treated pts, no difference was seen in TOT between MT vs WT (HR = 1.42 [0.73-2.8], p = 0.3], similarly in MSS pts (HR 1.175 [0.524–2.636], p = 0.7). Conclusions: In this real-world database, SWI/SNF alterations were associated with a significantly worse prognosis. There was no association with increased genomic instability of PDAC tumors, and in the cases with linked treatment data, there was no association with response to PARPi’s or ICI’s.

Systemic Therapy for Resected Pancreatic Adenocarcinoma: How Much is Enough?

BACKGROUND

Systemic therapy is an essential part of treatment for pancreatic ductal adenocarcinoma (PDAC). However, not all patients receive every cycle of chemotherapy and even if they do, the impact of reduced dose density (DD) on survival is not known.

PATIENTS AND METHODS

A single institutional prospective database was queried for patients with PDAC who underwent curative resection between 2009 and 2018. The primary outcome was DD, defined as the percentage of total planned chemotherapy actually received and associated survival.

RESULTS

Of the 126 patients included, 38.9% underwent a neoadjuvant approach, which was associated with a greater median number of completed chemotherapy cycles (5 cycles versus 4 cycles, p < 0.01) and a higher median total DD (93.0% versus 65.0%, p < 0.01), compared with an adjuvant treatment approach. In both groups, adjuvant chemotherapy completion rates were low, with only 55 patients completing all adjuvant cycles. After sequential survival analysis, patients who received a DD ≥ 80% had improved median overall survival (OS) (27.1 months versus 18.6 months, p = 0.01), compared with patients who achieved a DD < 80%. On multivariate Cox proportional-hazards modeling, only the presence of lymphovascular invasion (HR: 1.77, 95% CI: 1.04-2.99, p = 0.04) and DD < 80% (HR: 1.91, 95% CI: 1.23-3.00, p = 0.01) were associated with decreased OS.

CONCLUSIONS

In this cohort study, patients who received ≥ 80% DD had significantly better OS. DD should be considered an important prognostic metric in pancreatic cancer, and strategies are needed to improve chemotherapy tolerance to improve patient outcomes.

Efficacy and safety of larotrectinib in patients with TRK fusion-positive thyroid carcinoma

OBJECTIVE

Larotrectinib is a highly selective tropomyosin receptor kinase (TRK) inhibitor with demonstrated efficacy across various TRK fusion-positive solid tumours. We assessed the efficacy and safety of larotrectinib in patients with TRK fusion-positive thyroid carcinoma (TC).

METHODS

We pooled data from three phase I/II larotrectinib clinical trials (NCT02576431, NCT02122913, and NCT02637687). The primary endpoint was the investigator-assessed objective response rate (ORR) per Response Evaluation Criteria in Solid Tumors v1.1. Secondary endpoints included duration of response (DoR), progression-free survival (PFS), overall survival (OS), and safety. Data cut-off: July 2020.

RESULTS

Twenty-nine patients (median age: 60; range: 6-80) with TRK fusion-positive TC were treated. Tumour histology was papillary (PTC) in 20 (69%) patients, follicular (FTC) in 2 (7%), and anaplastic (ATC) in 7 (24%) patients. Among 28 evaluable patients, ORR was 71% (95% CI: 51-87); best responses were complete response in 2 (7%) patients, partial response in 18 (64%), stable disease in 4 (14%), progressive disease in 3 (11%), and undetermined in 1 (4%) due to clinical progression prior to the first post-baseline assessment. ORR was 86% (95% CI: 64-97) for PTC/FTC and 29% (95% CI 4-71) for ATC. Median time to response was 1.87 months (range 1.64-3.68). The 24-month DoR, PFS, and OS rates were 81, 69, and 76%, respectively. Treatment-related adverse events were mainly grades 1-2.

CONCLUSION

In TRK fusion-positive TC, larotrectinib demonstrates rapid and durable disease control and a favourable safety profile in patients with advanced disease requiring systemic therapy.

SIGNIFICANCE STATEMENT

NTRK gene fusions are known oncogenic drivers and have been identified in various histologies of thyroid carcinoma, most commonly in papillary thyroid carcinoma. This is the first publication specifically studying a TRK inhibitor in a cohort of TRK fusion-positive thyroid carcinoma patients. In the current study, the highly selective TRK inhibitor larotrectinib showed durable antitumour efficacy and a favourable safety profile in patients with TRK fusion-positive thyroid carcinoma. Our findings show that patients with advanced non-medullary thyroid carcinoma who may require systemic therapy could be considered for testing for gene fusions by next-generation sequencing.

A National Assessment of T2 Staging for Intrahepatic Cholangiocarcinoma and the Poor Prognosis Associated with Multifocality

BACKGROUND

T2 intrahepatic cholangiocarcinoma (ICC) is defined as a solitary tumors with vascular invasion or multifocal tumors including satellite lesions, multiple lesions, and intrahepatic metastases. This study aimed to evaluate the prognosis associated with multifocal tumors.

METHODS

The National Cancer Database was queried from 2004 to 2017 for patients with non-metastatic ICC. The patients were grouped based on T2 staging, multifocality, and lymph node involvement.

RESULTS

The study enrolled and classified 4887 patients into clinical (c) stage groups as follows: 15.2% with solitary T2N0 (sT2N0) tumors, 21.3% with multifocal T2N0 (mT2N0) tumors, and 63.5% with node-positive (TxN1) disease. Patients with (c)sT2N0 tumors had higher rates of surgical resection than those with (c)mT2N0 or (c)TxN1 disease (33.5% vs 19.7% vs 15.0%; p < 0.01). Median overall survival (OS) was better for the patients with (c)sT2N0 tumors than for those with multifocal and node-positive disease (15.4 vs 10.4 vs 10.4 months; p < 0.01). On multivariate analysis, (c)sT2N0 tumors were associated with better OS than (c)mT2N0 tumors [hazard ratio (HR), 1.31; 95% confidence interval (CI), 1.17-1.46; p < 0.01] or (c)TxN1 disease (HR,1.41; 95% CI 1.28-1.56; p < 0.01). In a subset analysis based on pathologic (p) staging of patients who underwent surgical resection with regional lymphadenectomy, multivariate analysis demonstrated that (p)sT2N0 tumors were associated with better OS than (p)mT2N0 tumors (HR,1.40; 95% CI 1.03-1.92; p = 0.03) or (p)TxN1 disease (HR, 2.05; 95% CI 1.62-2.58; p < 0.01).

CONCLUSIONS

Multifocal T2N0 ICC is associated with poor OS and has a disparate prognosis compared with solitary T2N0 disease, even among patients who undergo resection. Future staging criteria should account for the poor outcomes associated with multifocal ICC.

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

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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

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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)

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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.