Who Should Receive Immunotherapy for Advanced Gastroesophageal Cancer?

OPINION STATEMENT

This paper shines a light on the exciting progress being made in using immunotherapy to treat advanced gastroesophageal cancers. The positive results from trials using drugs like Pembrolizumab and Nivolumab are certainly encouraging and open new possibilities for treating this challenging disease. However, it is clear that we still have a lot to learn about how to predict which patients will benefit most from these treatments. The exploration of combining therapies and using machine learning to guide treatment shows promise. Moving forward, it is crucial that researchers and healthcare professionals continue to work together, sharing knowledge and findings to continue the advancements in this important area.

Differential responses to immune checkpoint inhibitors are governed by diverse mismatch repair gene alterations

PURPOSE

The response to immune checkpoint inhibitors (ICIs) in deficient mismatch repair (dMMR) colorectal cancer (CRC) and endometrial cancer (EC) is variable. Here, we explored the differential response to ICIs according to different MMR alterations.

EXPERIMENTAL DESIGN

CRC (N=13701) and EC (N=3315) specimens were tested at Caris Life Sciences. Median overall survival (mOS) was estimated using Kaplan-Meier. The prediction of high, intermediate and low affinity epitopes by tumor mutation burden (TMB) values was conducted using R-squared (R2) Results: Compared to mutL (MLH1 and PMS2) co-loss, the mOS was longer in mutS (MSH2 and MSH6) co-loss in all CRC (54.6m vs. 36m; p=0.0.025) and EC (81.5m vs. 48.2m; p<0.001) patients. In ICIs-treated patients, the mOS was longer in mutS co-loss in CRC (not reached (NR) vs. 36m; p=0.011). In EC, the mOS was NR vs. 42.2m; p=0.711). The neoantigen load (NAL) in mutS co-loss compared to mutL co-loss was higher in CRC (high-affinity epitopes: 25.5 vs 19; q=0.017, intermediate: 39 vs. 32; q=0.004, low: 87.5 vs. 73; q<0.001) and EC (high-affinity epitopes: 15 vs. 11; q=0.002, intermediate: 27.5 vs. 19; q<0.001, low: 59 vs. 41; q<0.001) respectively. R2 ranged from 0.25 in mutS co-loss CRC to 0.95 in mutL co-loss EC.

CONCLUSIONS

Patients with mutS co-loss experienced longer mOS in CRC and EC and better response to ICIs in CRC. Among all explored biomarkers, NAL was higher in mutS co-loss and may be a potential driving factor for the observed better outcomes. TMB did not reliably predict NAL.

The Efficacy of Immune Checkpoint Inhibitors in Microsatellite Stable Colorectal Cancer: A Systematic Review

The use of immune checkpoint inhibitors (ICIs) has revolutionized cancer care, particularly in immune-inflamed tumors and tumors with a high mutational burden, like microsatellite instable colorectal cancer (CRC). However, their effectiveness in microsatellite stable (MSS) CRC is limited. This systematic review aims to evaluate the efficacy of ICIs in MSS CRC and explore promising combination strategies. A comprehensive search from the Web of Science, Medline, and Embase databases, for studies published until 14 November 2022, identified 53 clinical trials included in the review. ICI monotherapy or ICI-ICI combinations demonstrated limited clinical activity for patients with MSS CRC, with overall response rates below (ORR) 10% in most studies. The ICI and tyrosine kinase inhibitor (TKI) garnered ORRs ranging from 10% to 40% and indicated a higher benefit for patients, particularly those without active liver metastases. The combination of ICIs with anti-VEGF agents showed modest ORRs, especially in the earlier treatment lines and in combination with chemotherapy. While these combinations could lead to modest improvements, well-defined biomarkers for long-term benefit are yet to be delineated. Combinations involving BRAF inhibitors with ICIs were studied, showing promising responses with combination approaches in molecularly defined subgroups. In conclusion, while ICI monotherapy has limited efficacy in MSS CRC, combination strategies hold promise to enhance survival outcomes. Further research is necessary to identify optimal combination approaches, predictive biomarkers for treatment response, as well as enrollment according to tumor molecular characteristics.

A Meta-Analysis to Assess the Efficacy of HER2-Targeted Treatment Regimens in HER2-Positive Metastatic Colorectal Cancer (mCRC)

Recent trials provide evidence that HER2 is a potential new target for patients with colorectal cancer. While HER2-positive tumors do not show a very encouraging response to anti-HER2-positive agents like trastuzumab alone, promising results have been observed when combined with other synergistically acting tyrosine kinase inhibitors (TKIs). Our meta-analysis was conducted following the Cochrane Handbook and written following the PRISMA guidelines. The protocol was registered on PROSPERO with the registration number CRD42022338935. After a comprehensive search for relevant articles, 14 CTs were identified and uploaded to Rayyan, and six trials were ultimately selected for inclusion. The meta-analysis revealed that a median of three prior lines of therapy was used before enrolling in the six trials comprising 238 patients with HER2-positive metastatic colorectal cancer (mCRC). The pooled objective response rate (ORR) and disease control rate (DCR) were 31.33% (95% confidence interval [CI] 24.27-38.39) and 74.37% (95% CI 64.57-84.17), respectively. The pooled weighted progression-free survival (PFS) was 6.2 months. The pooled ORR and DCR meta-analysis indicate a significant response to HER2-targeted therapy in this patient in HER2-positive mCRC. Additionally, a pooled PFS of 6.2 months suggests that HER2-targeted treatment regimens are associated with a meaningful improvement in survival outcomes in this population.

A Comprehensive Review on Cancer Vaccines and Vaccine Strategies in Hepatocellular Carcinoma

HCC, the most prevalent form of primary liver cancer, presents a substantial global health challenge due to its high mortality and limited therapeutic options. This review delves into the potential of cancer vaccines as a novel therapeutic avenue for HCC. We examine the various categories of cancer vaccines, including peptide-based, dendritic cell-based, viral vector-based, DNA, and mRNA vaccines, and their potential application in HCC management. This review also addresses the inherent challenges in vaccine development, such as tumor heterogeneity and the need for identifying tumor-specific antigens. We underscore the role of cancer vaccines in reshaping the immune environment within HCC, fostering durable immune memory, and their potential in combination therapies. The review also evaluates clinical trials and emphasizes the necessity for more extensive research to optimize vaccine design and patient selection criteria. We conclude with future perspectives, highlighting the significance of personalized therapies, innovative antigen delivery platforms, immune modulatory agents, and predictive biomarkers in revolutionizing HCC treatment. Simple Summary: This review explores the potential of cancer vaccines as a promising therapeutic strategy for hepatocellular carcinoma (HCC), a prevalent and deadly liver cancer. The authors discuss various types of cancer vaccines, their challenges, and their role in modulating the immune response within HCC. They also highlight clinical trials and future perspectives, emphasizing the importance of personalized therapies, novel antigen delivery platforms, and predictive biomarkers. The findings from this research could significantly impact the research community by providing a comprehensive understanding of the current state of cancer vaccines for HCC, thereby guiding future research and potentially transforming HCC treatment strategies.

Neoadjuvant Immunotherapy for Patients with dMMR/MSI-High Gastrointestinal Cancers: A Changing Paradigm

Immune checkpoint inhibitors have revolutionized the management of mismatch repair-deficient (MMR-D)/microsatellite instability-high (MSI-H) gastrointestinal cancers, particularly colorectal cancer. Cancers with the MMR-D/MSI-H genotype often carry a higher tumor mutation burden with frameshift alterations, leading to increased mutation-associated neoantigen (MANA) generation. The dramatic response seen with immune checkpoint inhibitors (ICIs), which are orchestrated by MANA-primed effector T cells, resulted in the rapid development of these novel therapeutics within the landscape of MSI-H gastrointestinal cancers. Recently, several clinical trials have utilized ICIs as potential neoadjuvant therapies for MSI-H gastrointestinal cancers and demonstrated deep clinical and pathological responses, creating opportunities for organ preservation. However, there are potential challenges to the neoadjuvant use of ICIs for certain disease types due to the clinical risk of overtreatment for a disease that can be cured through a surgery-only approach. In this review article, we discuss neoadjuvant management approaches with ICI therapy for patients with MSI-H gastrointestinal cancers, including those with oligometastatic disease. We also elaborate on potential challenges and opportunities for the neoadjuvant utilization of ICIs and provide further insight into the changing treatment paradigm of MMR-D/MSI-H gastrointestinal cancers.

Next generation immuno-oncology biomarkers in gastrointestinal cancer: what does the future hold?

INTRODUCTION

Gastrointestinal (GI) cancers pose a significant health burden worldwide, necessitating advancements in diagnostic and treatment approaches. One promising avenue is the utilization of next-generation biomarkers, which hold the potential to revolutionize GI cancer management.

AREAS COVERED

This review explores the latest breakthroughs and expert opinions surrounding the application of next-generation immunotherapy biomarkers. It encompasses various aspects of the currently utilized biomarkers of immunotherapy in the context of GI cancers focusing on microsatellite stable cancers. It explores the promising research on the next generation of biomarkers addressing the challenges associated with integrating them into clinical practice and the need for standardized protocols and regulatory guidelines.

EXPERT OPINION

Immune profiling, multiplex immunohistochemistry, analysis of immune cell subsets, and novel genomic and epigenomic markers integrated with machine-learning approaches offer new avenues for identifying robust biomarkers. Liquid biopsy-based approaches, such as circulating tumor DNA (ctDNA) and exosome-based analyses, hold promise for real-time monitoring and early detection of treatment response.

The role of immune checkpoint inhibitors for patients with advanced stage microsatellite stable colorectal cancer and high tumor mutation burden: quantity or quality?

INTRODUCTION

The US Food and Drug Administration (FDA) approved pembrolizumab for patients with unresectable or metastatic solid tumors with tumor mutational burden (TMB) of ≥ 10 mutations/megabase. However, the clinical implications of this universal cutoff of TMB ≥ 10 for patients with microsatellite stable (MSS) metastatic colorectal cancer (CRC) remain debatable.

AREAS COVERED

In this review, we discuss the tissue agnostic approval of pembrolizumab, its efficacy, and clinical relevance in the management of patients with MSS CRC patients with high TMB (defined as TMB ≥ 10). We also elaborate on molecular subgroups of MSS CRC that influence the immune checkpoint inhibitor (ICI) response for patients with MSS CRC, including pathogenic POLE and POLD1 mutations associated with ultramutated tumors.

EXPERT OPINION

Patients with microsatellite stable CRC with TMB ≥ 10 without POLE and POLD1 mutations may not benefit significantly from immune checkpoint inhibitors therapy. Predetermined cutoff TMB ≥ 10 mutation per MB does not seem to define a universal cutoff for the benefit of disease-agnostic ICI therapy, particularly for patients with MSS CRC. Patients with POLE/POLD1 mutations with MSS CRC represent a unique biological subgroup of MSS CRC with favorable responses to ICI therapy.

Neoadjuvant Immune Checkpoint Inhibitor Therapy for Patients With Microsatellite Instability-High Colorectal Cancer: Shedding Light on the Future

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment paradigm of mismatch repair-deficient/microsatellite instability-high (MMMR-D/MSI-H) colorectal cancer (CRC). Unique molecular features of MMR-D/MSI-H CRC with frameshift alterations, which result in mutation-associated neoantigen (MANA) generation, create an ideal molecular framework for MANA-driven T-cell priming and antitumor immunity. These biologic characteristics of MMR-D/MSI-H CRC resulted in rapid drug development with ICIs for patients with MMR-D/MSI-H CRC. Observed deep and durable responses with the use of ICIs in advanced-stage disease have stimulated the development of clinical trials with ICIs for patients with early-stage MMR-D/MSI-H CRC. Most recently, neoadjuvant dostarlimab monotherapy for nonoperative management of MMR-D/MSI-H rectal cancer and neoadjuvant NICHE trial with nivolumab and ipilimumab for MMR-D/MSI-H colon cancer resulted in groundbreaking results. Although nonoperative management of patients with MMR-D/MSI-H rectal cancer with ICIs will potentially define our current therapeutic approach, therapeutic goals of neoadjuvant ICI therapy for patients with MMR-D/MSI-H colon cancer may differ given that nonoperative management has not been well established for colon cancer. Herein, we overview recent advancements in ICI-based therapies for patients with early-stage MMR-D/MSI-H colon and rectal cancer and elaborate on the future treatment paradigm of this unique subgroup of CRC.

Systemic Therapy for Patients With Pancreatic Cancer: Current Approaches and Opportunities for Novel Avenues Toward Precision Medicine

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis with a 5-year overall survival of 11%. The disease is usually diagnosed at advanced stages, and systemic chemotherapy is the standard-of-care treatment for the majority of patients with PDAC. Although novel treatment options, such as targeted therapy and immunotherapy, have achieved substantial progress leading to practice-changing results, with FDA approvals for several solid tumors so far, the progress achieved for PDAC is relatively limited. Recent studies uncovered potential therapeutic targets for patients with PDAC, and potential therapeutic opportunities are currently being further examined. Herein, we review recent advances in systemic therapy regimens, including cytotoxic agents, targeted therapies, immunotherapy, and novel therapeutic options for managing patients with PDAC. We also elaborate on molecular profiling to guide treatment and existing therapeutic opportunities that may further advance the clinical care of patients with this devastating disease.

Effect of immunotherapy on the survival outcomes in tumor mutational burden-high (TMB-H) microsatellite stable (MSS) metastatic colorectal cancer (mCRC): A single-institution experience

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Background: The benefit of immunotherapy for patients with mCRC with high tumor mutational burden (TMB-H) has been widely debated. In 2020, the FDA approved the use of pembrolizumab for the treatment of patients with TMB-H unresectable or metastatic solid tumors, with TMB-H defined as ≥10 mutations/Mb on a commercial tissue-based assay, based on KEYNOTE 158 results. However, the clinical value of applying this universal cut off to mCRC needs further investigation. Methods: We queried Moffitt Cancer Center (MCC) databases for patients with MSS mCRC, harboring TMB-H (tested with tissue and/or liquid biopsies) who received immunotherapy between January 2018 and December 2021. Patients with incomplete records were excluded. Clinical data were extracted by trained staff from electronic medical records. Objective response rate was measured by using clinical assessment from chart review. Results: We identified 40 patients with TMB-H MSS mCRC 13 of whom received immune checkpoint inhibitor therapy. Female patients represented 31% (n=4) of the 13 treated patients. Median age for the patients was 60 years (range 34-71. Thirty-eight percent (n=5) of the primary tumors originated in the right side. Thirty-one percent (n=4) presented with stage 4 CRC at diagnosis. Histopathology was adenocarcinoma in 92% (n=12) and one had neuroendocrine differentiation. Tumors were well-differentiated 8% (n=1), moderately differentiated 46% (n=6), or poorly differentiated 23% (n=3). Four patients (31%) had POLE/ POLD-1 mutations. The objective response rate (ORR) was 31% (4/13) with responses limited to tumors only with POLE/ POLD-1 mutations (100%, 4/4). The median progression free survival (mPFS) was 3.8 months for the overall cohort and 28.5 months for patients with POLE/POLD-1 mutated tumors. Agent specific analysis showed mPFS for patients treated with pembrolizumab was 3.5 months (mean 5.2; range 0.6-15.7), and 3.4 months (mean 12.1; range 0.5-12.1) for patients treated with nivolumab. Five patients received immunotherapy in combination with regorafenib. The mPFS for these patients was 3.4 months (mean 3.8; range 0.5-8.0). Of five patients with TMB>30 (38%), 4 (80%) had POLE/POLD-1 mutated tumors. One case without POLE/POLD-1 mutations, but with a TMB>30 did not experience any response. Conclusions: Although TMB-H demonstrated therapeutic significance in the KEYNOTE 158 study, the utility of 10 mutations/MB as a universal cutoff warrants additional evaluation. Here we report that a TMB-H cutoff value of ≥ 10 for patients with MSS CRC was not associated with clinically meaningful response to immunotherapy, but patients with MSS CRC with POLE/ POLD-1 mutations may be more likely to benefit from immunotherapy.

NRG GI008: Colon adjuvant chemotherapy based on evaluation of residual disease (CIRCULATE-US)

TPS260

Background: Currently, there are no biomarkers validated prospectively in randomized studies for resected colon cancer (CC) to determine need for adjuvant chemotherapy (AC). However, circulating tumor DNA (ctDNA) represents a highly specific and sensitive approach (especially with serial monitoring) for identifying minimal/molecular residual disease (MRD) post-surgery in CC patients (pts), and may outperform traditional clinical and pathological features in prognosticating risk for recurrence. CC pts who do not have detectable ctDNA (ctDNA-) are at a much lower risk of recurrence and may be spared the toxicities associated with AC. Furthermore, for CC pts with detectable ctDNA (ctDNA+) who are at a very high risk of recurrence, the optimal AC regimen has not been established. We hypothesize that for pts whose CC has been resected, ctDNA status may be used to risk-stratify for making decisions about AC. Methods: In this prospective phase II/III trial, up to 1,912 pts with resected stage III A, B (all pts) and stage II, IIIC (ctDNA+ only) CC will be enrolled. Based on the post-operative ctDNA status using personalized and tumor-informed assay (Signatera™, bespoke assay), those who are ctDNA- (Cohort A) will be randomized to immediate AC with fluoropyrimidine (FP) + oxaliplatin (Ox) for 3-6 mos per established guidelines vs . serial ctDNA monitoring. Patients who are ctDNA+ post-operatively or with serial monitoring (Cohort B) will be randomized to FP+Ox vs . more intensive AC with addition of irinotecan (I) for 6 mos. The primary endpoints for Cohort A are time to ctDNA+ status (phase II) and disease-free survival (DFS) (phase III) in the immediate vs . delayed AC arms. The primary endpoint for Cohort B is DFS in the FP+Ox vs FP+Ox+I arms for both phase II and phase III portions of the trial. Secondary endpoints include prevalence of detectable ctDNA post-operatively, time-to-event outcomes (overall survival and time to recurrence) by ctDNA status, and the assessment of compliance to adjuvant therapy. Biospecimens including archival tumor tissue, as well as post-operative plus serial matched/normal blood samples, will be collected for exploratory correlative research. Active enrollment across the NCTN started in June, 2022. Support: U10-CA-180868, -180822; UG1CA-189867; Natera, Inc. Clinical trial information: NCT05174169 .

The benefit of immunotherapy in patients with hepatocellular carcinoma: a systematic review and meta-analysis

Background: A systemic review of the survival benefit of immune checkpoint inhibitors (ICIs) in phase III hepatocellular carcinoma (HCC) trials was conducted. Methods: Meta-analyses were performed with the generic inverse-variance method with a fixed-effects model. Results: In 10 trials encompassing 6123 patients, ICI-based therapy (monotherapy/combination) improved overall survival (OS) compared with the control arm (hazard ratio [HR]: 0.77; 95% CI: 0.70-0.84; p < 0.001). The survival benefit was consistent across variable treatment lines, Eastern Cooperative Oncology Group performance status and AFP levels. While the OS benefit was more pronounced in hepatitis B-related HCC (HR: 0.70; 95% CI: 0.63-0.77; p < 0.001), OS was improved in hepatitis C-related (HR: 0.83; 95% CI: 0.71-0.98) and nonviral HCC (HR: 0.86; 95% CI: 0.77-0.97). Conclusion: ICI-based therapies should be the standard for all patients with advanced HCC.

Minimal Residual Disease-Directed Adjuvant Therapy for Patients With Early-Stage Colon Cancer: CIRCULATE-US

BACKGROUND

The ability to detect circulating tumor DNA (ctDNA), a novel surrogate for minimal residual disease (MRD) for patients with solid tumors, has significantly evolved over the past decade. Several studies have shown that ctDNA may provide clinical insight into the biological dynamics of MRD. The CIRCULATE-US (NRG-GI008; NCT05174169) trial will aim to address the role of ctDNA for risk stratification to intensify and deintensify adjuvant chemotherapy for patients with early-stage colon cancer.

METHODS

CIRCULATE-US, a prospective phase 2/3 randomized trial, is investigating the molecular dynamics and prognostic role of ctDNA (evaluated by Natera's Signatera assay) for patients with resected colon cancer. Patients with negative postoperative ctDNA will be enrolled in cohort A and randomized to receive either immediate treatment with 5-fluorouracil and folinic acid or capecitabine plus oxaliplatin (FOLFOX6 or CAPEOX; Arm 1) or serial ctDNA surveillance with delayed adjuvant therapy (Arm 2). Patients randomized to Arm 2 with subsequent positive ctDNA results will be enrolled in cohort B for a second randomization to receive either FOLFOX6/CAPEOX (Arm 3) or 5-fluorouracil, folinic acid, oxaliplatin, and irinotecan (FOLFIRINOX; Arm 4) for 6 months. Patients with positive postoperative ctDNA results will be directly enrolled in cohort B and randomized to receive either FOLFOX6/CAPEOX (Arm 3) or FOLFIRINOX (Arm 4). Patients with stage II or stage IIIC colon cancer with positive ctDNA results (tested as standard of care with commercial testing) will be eligible for enrollment in cohort B. The primary end point for cohort A is time to positive ctDNA status for phase 2 and disease-free survival for phase 3 with a noninferiority design. The primary end point for cohort B is disease-free survival for both phase 2 and phase 3 with a superiority design.

DISCUSSION

CIRCULATE-US will aim to understand postoperative ctDNA dynamics in early-stage colon cancer and will investigate escalation and de-escalation approaches by using ctDNA status as a surrogate for MRD status.

Immunotherapy for Microsatellite Stable Colorectal Cancers: Challenges and Novel Therapeutic Avenues

With the development of immune checkpoint inhibitors, immunotherapy researchers have facilitated substantial progress for patients with mismatch repair deficient/microsatellite instability-high colorectal cancer, which has led to practice changes at a head-spinning pace. However, this benefit has not been translated into microsatellite stable colorectal cancer, which carries the hallmarks of chromosomal instability. So far, clinical trials have not shown any substantial clinical benefits of immune checkpoint inhibitor therapy for patients with microsatellite stable colorectal cancer, which has been disappointing. Recently, combinations of immune checkpoint inhibitors with tyrosine kinase inhibitors and targeted therapies have been investigated for potential synergistic effects that may increase antitumor activity in the tumor microenvironment and achieve more substantial clinical and radiologic responses. In this article, we discuss the current state of the science for the use of immune checkpoint inhibitors in microsatellite stable colorectal cancers, and we review the molecular underpinnings of inherited physiologic barriers for the delivery of effective immunotherapy. We also elaborate on existing therapeutic opportunities to convert microsatellite stable colorectal cancer into an "immune hot" cancer, which may define the future treatment paradigm of colorectal cancer for which there is a great unmet need.

Clinical and molecular characterization of fusion genes in colorectal cancer

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Background: Next-generation sequencing (NGS) based molecular profiling technologies have revealed several oncogenic fusion genes that are actionable with small molecule inhibitors leading to practice change, particularly in lung cancer. The molecular and clinical characteristics of these gene fusions are not well defined in colorectal cancer patients (CRC). In this study, we aimed to define clinical and molecular characteristics of fusion genes in patients with CRC who underwent molecular profiling. Methods: Molecular characteristics of tissue confirmed 917 CRC patients were retrieved from the Moffit Cancer Center Clinical Genomics Action Committee database. Patients’ demographic and clinicopathological features and treatment history were collected from the database. All fusion genes were shown by hybridization-based NGS computational algorithms that determined cancer‐related genes, including single‐nucleotide variations, indels, microsatellite instability (MSI) status. Results: Among a total of 917 patients, 24 patients with CRC (2.6%) were found to have at least one fusion gene with a total number of 26 pathogenic fusions. The gene fusions are shown in Table. The most common, potentially targetable, fusion genes in our cohort were (1) RET fusions 0.5% (5/917), (2) ALK fusions 0.4% (4/917), (3) ROS1 fusions 0.2% (2/917), (4) NTRK1 fusion 0.1% (1/917), (5) NRG1 fusion 0.1% (1/917). Fusion genes were more common in MSI-H CRC (N = 27), and 3 (11.1%) patients with MSI-H CRC were found to have fusion genes [(RET (2) and NTRK(1)]. Fusion genes were present in both RAS wild-type (54%; 13/24) and RAS mutant (46%; 11/24) tumors. Most patients were older than 50 years (75%, 18/24) and had left-sided tumor (61.1%) tumor. Conclusions: Fusion genes are rare events in CRC. While fusion genes seem to be more prevalent in MSI-H CRC, RAS status does not correlate with the frequency of fusion genes. Actionable RET and ALK/ROS gene fusion are more common than NTRK fusion genes in this cohort of CRC patients.[Table: see text]

The impact of HRD in patients with pancreatic adenocarcinoma undergoing surgical resection: An updated analysis

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Background: Limited data is available regarding which mutations in the homologous recombination repair (HRR) pathway beyond BRCA can be targeted with platinum-based chemotherapy in the perioperative setting in patients with pancreatic ductal adenocarcinoma (PDAC). In this updated analysis, we assess the outcome of patients with homologous recombination deficiency (HRD) in response to platinum vs. non-platinum based perioperative chemotherapy in resected PDAC and have included additional variants linked to HRD. Methods: Patients with resectable PDAC, diagnosed between 1999-2020 from the participating members of the Oncology Research Information Exchange Network (ORIEN) were included in the study. Patient’s germline and somatic whole exome sequencing (WES) data were analyzed for known pathogenic and likely pathogenic variants according to ClinVar for the following HRR pathway genes: BRCA1, BRCA2, PALB2, BRIP1, BRAD1, BLM, BAP1, ATM, RAD51C, RAD51, RAD50, RAD54B, CHECK2, NBN, FANCA/B/C/D2/E/F/G, ARID1A, MRE11 and XRCC2. The Kaplan Meier method was used to compare median overall survival (mOS) between patients with and without HRR pathway mutations in response to perioperative platinum vs non-platinum-based chemotherapy. Multivariate cox proportional hazard model was used to calculate HR and 95% CIs adjusting for age, sex and pathologic stage. Results: The ORIEN cohort included 311 patients with resectable PDAC and available WES data. A total of 22 patients (7%) had an HRR pathway mutation. Of these, 8 (36%) received perioperative platinum-based chemotherapy and 9 (41%) a non-platinum based regimen, 4 patients (23%) received no perioperative systemic treatment. Frequency of HRR variants detected: BRCA2 n=8 (2.6%), BRCA1 n=3 (1%), ATM n=2 (0.6%), ARID1A n=1 (0.3%), BRIP1 n=1 (0.3%), CHECK2 n=1 (0.3%), FANCG n=1 (0.3%), PALPB2 n=1 (0.3%), RAD50 n=4 (1.3%), RAD51C n=1 (0.3%). The mOS for patients with HRR mutations exposed to perioperative platinum-based chemotherapy was 3.5 years (95% CI 3.4-NA), patients with HRR mutation but no platinum exposure had a mOS of 1.2 years (CI 0.9-NA). In patients with no HRR mutation exposed to platinum-based chemotherapy mOS was 2.7 years (CI 2.3-3.9) and in those without exposure mOS was 2.9 years, p=0.43. Comparison of risk of death between the 4 groups is demonstrated in the table. Conclusions: There was a trend towards improved survival in patients with PDAC who harbored a HRR pathway mutation and were treated with perioperative platinum-based chemotherapy compared to those with no platinum exposure. Our results highlight the importance of identifying patients with HRD beyond BRCA and the need for large prospective studies in the perioperative setting to further assess their predictive role. [Table: see text]

Colon adjuvant chemotherapy based on evaluation of residual disease (CIRCULATE-US): NRG-GI008

TPS3643

Background: Currently, there are no biomarkers validated prospectively in randomized studies for resected colon cancer (CC) to determine need for adjuvant chemotherapy (AC). However, circulating tumor DNA (ctDNA) represents a highly specific and sensitive approach (especially with serial monitoring) for identifying minimal/molecular residual disease (MRD) post-surgery in CC patients (pts), and may outperform traditional clinical and pathological features in prognosticating risk for recurrence. CC pts who do not have detectable ctDNA (ctDNA-) are at a much lower risk of recurrence and may be spared the toxicities associated with AC. Furthermore, for CC pts with detectable ctDNA (ctDNA+) who are at a very high risk of recurrence, the optimal AC regimen has not been established. We hypothesize that for pts whose CC has been resected, ctDNA status may be used to risk stratify for making decisions about AC. Methods: In this prospective phase II/III trial, up to 1,912 pts with resected stage III A, B (all pts) and stage II, IIIC (ctDNA+ only) CC will be enrolled. Based on the post-operative ctDNA status using personalized and tumor informed assay (SignateraTM, bespoke assay), those who are ctDNA- (Cohort A) will be randomized to immediate AC with fluoropyrimidine (FP) + oxaliplatin (Ox) for 3-6 mos per established guidelines vs . serial ctDNA monitoring. Patients who are ctDNA+ post-operatively or with serial monitoring (Cohort B) will be randomized to FP+Ox vs . more intensive AC with addition of irinotecan (I) for 6 mos. The primary endpoints for Cohort A are time to ctDNA+ status (phase II) and disease-free survival (DFS) in phase III in the immediate vs . delayed AC arms. The primary endpoint for Cohort B is DFS in the FP+Ox vs FP+Ox+I arms for both phase II and phase III portions of the trial. Secondary endpoints include prevalence of detectable ctDNA post-operatively, time-to-event outcomes (overall survival and time to recurrence) by ctDNA status, and the assessment of compliance to adjuvant therapy. Biospecimens including archival tumor tissue, post-operative and serial matched/normal blood samples will be collected for exploratory correlative research. Active enrollment across the NCTN started in early 2022. Support: U10-CA-180868, -180822; UG1CA-189867; Clinical trial information: NCT05174169.

Characterization of NTRK alterations in metastatic colorectal cancer

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Background: Increased molecular profiling ability has resulted in the recognition of important actionable genes that can be used to direct targeted therapies in colorectal cancers (CRC). Neurotrophin receptor tyrosine kinase (NTRK) gene fusions are one of these molecular alterations that are potentially actionable with novel targeted therapeutics. However, other biologically pathogenic NTRK alterations, including point mutations, are not yet actionable in CRC. This study aimed to characterize NTRK alterations, including fusions in metastatic CRC patients. Methods: Molecular characteristics of 917 patients with CRC were collected from the Moffitt Cancer Center Clinical Genomics Action Committee database. Demographic, clinicopathological, and molecular data and treatment history were abstracted from electronic medical records. Mutations with potential oncogenic activity are considered “potentially pathogenic”, while alterations with proven oncogenic activity such as fusions are considered “pathogenic”. Results: There were 917 patients with CRC from November 2013 to December 2021, and 77 of them had NTRK alterations excluding synonymous mutations (8.3%, 77/917). Six patients had potentially pathogenic NTRK alterations, including one NTRK rearrangement (0.6%, 7/917); however, only 1 patient had an actionable pathogenic NTRK1 fusion (0.1%, 1/917), while the others (70) were a variant of unknown significance (VUS). The majority of NTRK alterations were missense mutations (92%; 71/77). The NTRK1 fusion partner was LMNA and occurred in the setting of an MSI-H tumor (3.7%; 1/27). Among patients with pathogenic and potentially pathogenic alterations (N = 7), there was only 1(14%) patient who had low tumor mutation burden (TMB) (< 10 mut/MB). Most patients were older than 50 years (70.1%, 54/77) and male (58.4%, 45/77). Thirty-six patients (46..7%) had right-sided tumor, while 41 patients (53.2%) left-sided. Across all NTRK alterations cohort, MSI-H was found in 10.3% (7/77), and POLE/POLD1 pathogenic mutations were seen in 6.4% (5/77) patients. Conclusions: NTRK gene fusion is a relatively rare event (< 1%) in CRC, including the MSI-H subtype. The majority of NTRK alterations in CRC are VUS, and they are not actionable, and they tend to be seen in the tumors with high TMB (TMB > 10). Hypermutator tumors cause frequent VUS alterations in the NTRK gene with unknown clinical relevance.

Human Epidermal Growth Factor Receptor 2-Targeting Approaches for Colorectal Cancer: Clinical Implications of Novel Treatments and Future Therapeutic Avenues

The treatment paradigm for colorectal cancer (CRC) has changed significantly over the past decade with targeted therapeutics. Human epidermal growth factor receptor 2 (HER2) amplification is seen among 3%-4% of patients with metastatic CRC (mCRC). The biological discovery of HER2 amplification in cancer cells has led to practice-changing drug development for several solid tumors, including breast, gastric, and esophageal cancers. HER2 amplification is now highly actionable in CRC with distinct therapeutic combinations, including the combination of monoclonal antibodies and HER2 receptor-specific tyrosine kinase inhibitors, as well as antibody-drug conjugates, that delivers targeted cytotoxic agents. However, it is essential to define the therapeutic role and sequence of these different combinations, some of which are already part of standard clinical practice. In this review article, we discuss recent clinical studies demonstrating the clinical benefits of each distinct therapeutic approach and their impacts on the current management of HER2-amplified mCRC. We also review ongoing clinical trials targeting the HER2 pathway in mCRC and elaborate on novel therapeutic opportunities in this space that may further define the changing paradigm of HER2-targeted therapy for CRC.

BRAF Mutations Are Associated with Poor Survival Outcomes in Advanced-stage Mismatch Repair-deficient/Microsatellite High Colorectal Cancer

Background

Mismatch repair-deficient (MMR-D)/microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC) is a unique disease entity with growing interest given the rise of young-onset CRC. Given its heterogeneous behavior and potential for highly effective treatment outcomes, we sought to identify the clinical and molecular features that offer prognostic value for MMR-D CRC.

Materials/Methods

This was a retrospective cohort study of patients with metastatic CRC with MMR-D or microsatellite instability in a real-world database. Overall survival (OS) was determined by the date of metastatic disease to date of death with stratification made based on factors including BRAF and RAS mutation status, age, and MMR protein loss type.

Results

There were 1101 patients in the study. Patients with BRAF mutations had worse OS compared with patients with wild-type BRAF with a median survival of 18.9 months versus 33.2 months (hazard ratio [HR] 1.52, 95% confidence interval [CI]: 1.25-1.86, P < .001). Patients with age >50 were found to have decreased OS versus age ≤50 with a median survival of 21.4 months versus 38.7 months (HR 1.66, 95% CI: 1.33-2.07, P < .001). BRAF mutations and age >50 remained significant predictors of OS in multivariate analysis.

Conclusion

BRAF mutations and age >50 are associated with worse survival outcomes for patients with MMR-D mCRC. RAS mutations and specific MMR alterations are not associated with survival outcomes.

Mismatch Repair (MMR) Gene Alteration and BRAF V600E Mutation Are Potential Predictive Biomarkers of Immune Checkpoint Inhibitors in MMR-Deficient Colorectal Cancer

BACKGROUND

Immune checkpoint inhibitor (ICI) therapy is highly effective in metastatic mismatch repair-deficient (MMR-D) colorectal cancer (CRC). In this study, we evaluated molecular and clinical predictors of ICI response in MMR-D CRC.

MATERIALS AND METHODS

Patient databases at four cancer institutions were queried. The Fisher exact test was performed to test the association of clinical and molecular markers. The Kaplan-Meier method was used to estimate progression-free survival (PFS) and compared by the log-rank test. Twelve- and 24-month PFS rates were compared by the Z test.

RESULTS

A total of 60 patients with CRC with MMR-D/microsatellite instability-high who previously received ICIs were identified. Patients with liver metastasis had a lower overall response rate as compared with other sites of metastasis (36.4% vs. 68.7%; p = .081). Patients with MLH1/PMS2 loss had worse 1-year and 2-year PFS rates compared with patients with MSH2/MSH6 loss (84.2% vs. 57.8% and 78.2% vs. 54.2%, respectively; p < .001). There were improved 1-year and 2-year PFS rates in patients with wild-type BRAF when compared with patients with BRAF V600E mutation (73.3% vs. 40%, and 73.3% vs. 26.7%; respectively; p < .001). Patients aged >65 had significantly worse PFS rates as compared with patients aged ≤65 (p < .001).

CONCLUSION

BRAF V600E mutation, MLH1 and/or PMS2 loss, as well as age >65 years and liver metastasis, may be predictive of duration of ICI response in patients with MMR-D CRC. Larger cohorts are needed to confirm our findings.

IMPLICATIONS FOR PRACTICE

The results of this study reveal clinically important biomarkers that potentially predict immune checkpoint inhibitor response in patients with mismatch repair-deficient colorectal cancer.

Defining the current role of immune checkpoint inhibitors in the treatment of mismatch repair-deficient/microsatellite stability-high colorectal cancer and shedding light on future approaches

Introduction: Mismatch repair deficient (MMR-D)/microsatellite instability-high (MSI-H) colorectal cancer (CRC) carries unique biologic features including high tumor mutation burden, increased amount of mutation-associated neoantigen generation, and the presence of marked tumor-infiltrating lymphocytes. Immune checkpoint inhibitor (ICI) therapy has rapidly changed the treatment algorithm of MMR-D/MSI-H CRC.Areas covered: In this review article, we discuss the recent data regarding the use of ICIs in metastatic MMR-D/MSI-H CRC patients. We also elaborated on potential biomarkers of ICI response and innovative therapeutic approaches that may prevail resistance mechanisms for the treatment of MMR-D/MSI-H colorectal cancer.Expert opinion: Pembrolizumab was recently granted approval by the FDA as first-line therapy for metastatic MMR-D/MSI-H CRC based on the results of the Keynote 177 study. The combination of nivolumab and ipilimumab will also likely be a choice for the initial therapy of MMR-D/MSI-H CRC in the near future. More therapeutic modalities with novel immunomodulatory agents as well as targeted therapy directed to immune resistance pathways are needed. The novel approaches discussed in this review article will define potential treatment options for the management of MMR-D/MSI-H CRC patients who progress on first-line ICI therapy.

BRAF Mutations as Actionable Targets: A Paradigm Shift in the Management of Colorectal Cancer and Novel Avenues

BRAF mutations in colorectal cancer have been studied over the past several decades. BRAF V600E mutation, a class I mutation, is the most common oncogenic BRAF alteration in colorectal cancer. Until recently, the BRAF V600E mutation was not among actionable genes for colorectal cancer. However, recent discoveries have revealed therapeutic opportunities. The BRAF with or without MEK inhibition combined with epidermal growth factor receptor-directed therapy was recently found to be an effective therapy choice for patients with advanced-stage BRAF V600-mutant colorectal cancer. However, it is essential to distinguish patients with BRAF V600E-mutant mismatch repair-deficient colorectal cancer from those with mismatch repair-proficient colorectal cancer, as immune checkpoint inhibitor therapy is more appealing in this subset of patients with colorectal cancer. This review article discusses the molecular characteristics of class I, II, and III BRAF mutants and their impact on the clinical behavior of colorectal cancer. We also review the recent progress in the targetability of BRAF mutations in colorectal cancer, which has led to changes in clinical practice and elaborates on innovative therapeutic approaches to enhance the efficacy of BRAF-targeting therapies, to achieve more durable responses.

Pancreatic cancer stem cells may define tumor stroma characteristics and recurrence patterns in pancreatic ductal adenocarcinoma

BACKGROUND

Herein, we investigate the relationship between pancreatic stem cell markers (PCSC markers), CD44, and epithelial-specific antigen (ESA), tumor stroma, and the impact on recurrence outcomes in pancreatic ductal adenocarcinoma (PDAC) patients.

METHODS

PDAC patients who underwent surgical resection between 01/2012-06/2014 were identified. CD44 and ESA expression was assessed by immunohistochemistry. Stroma was classified as loose, moderate, and dense based on fibroblast content. Overall survival (OS) and relapse-free survival (RFS) were estimated using the Kaplan-Meier method and compared between subgroups by log-rank test. The association between PCSC markers and stroma type was assessed by Fisher's exact test.

RESULTS

N = 93 PDAC patients were identified. The number of PDAC patients with dense, moderate density, and loose stroma was 11 (12%), 51 (54%), and 31 (33%) respectively. PDAC with CD44+/ESA- had highest rate of loose stroma (63%) followed by PDAC CD44+/ESA+ (50%), PDAC CD44-/ESA+ (35%), CD44-/ESA- (9%) (p = 0.0033). Conversely, lack of CD44 and ESA expression was associated with the highest rate of moderate and dense stroma (91% p = 0.0033). No local recurrence was observed in patients with dense stroma and 9 had distant recurrence. The highest rate of cumulative local recurrence was observed in patients with loose stroma. No statistically significant difference in RFS and OS was observed among subgroups (P = 0.089).

CONCLUSIONS

These data indicate PCSCs may have an important role in stroma differentiation in PDAC. Our results further suggest that tumor stroma may influence the recurrence pattern in PDAC patients.

Neoadjuvant and adjuvant treatment approaches for hepatocellular carcinoma: future outlook

Hepatocellular carcinoma (HCC) is a highly aggressive and chemotherapy resistant cancer with unique biologic characteristics which makes this disease highly different than other gastrointestinal cancers. The mainstay of curative treatment in HCC is surgical resection, ablation, and transplantation. However, rates of recurrence are high and many patients are not initially candidates for these curative approaches. This paper discusses predictors of recurrence of HCC in patients who have undergone surgical resection and addresses adjuvant therapies aimed at decreasing recurrence risk and improving overall survival (OS) outcomes, including traditional cytotoxic chemotherapies, tyrosine kinase inhibitors (TKIs), and immunotherapy. This article also discusses neoadjuvant strategies aimed at improving recurrence rate and OS as well as downstaging advanced HCC to enable surgical disease, including locoregional therapies, systemic chemotherapy, TKIs, and immune checkpoint inhibitors. Finally, this article addresses potential future directions for both adjuvant and neoadjuvant therapies that may change the treatment paradigm of HCC in the near future.

Regorafenib, an investigational agent for the treatment of cholangiocarcinoma

INTRODUCTION

Cholangiocarcinoma is a prevalent gastrointestinal cancer with a high mortality rate. A limited number of cholangiocarcinoma patients are diagnosed with early-stage disease but unfortunately, most patients present with an advanced-stage disease which is not amenable to curative surgical resection.

AREAS COVERED

We discuss regorafenib, a multi-kinase inhibitor, which has been investigated as a therapeutic agent in advanced stage biliary tract cancer patients in phase II trials. We examined the efficacy and toxicity of this agent and its potential in this patient population in the future. We also provide further insights on novel approaches to optimize the efficacy of regorafenib in cholangiocarcinoma patients.

EXPERT OPINION

The recent phase II trials of single-agent regorafenib in advanced stage biliary tumors revealed a modest activity in non enriched patient population and is currently part of the national comprehensive cancer network (NCCN) guidelines (Level 2B) in the refractory setting. However, more opportunities for this agent exist in combination approaches with other therapeutics such as immune checkpoint inhibitors. It is also important to recognize that the paradigm has significantly shifted for targeted therapy to more specific and more potent tyrosine kinase inhibitors targeting specific actionable genes.

The tumor microenvironment of pancreatic adenocarcinoma and immune checkpoint inhibitor resistance: a perplex relationship

Pancreatic cancer is one of the most aggressive cancers with a high mortality rate even among patients with early-stage disease. Although recent studies with novel therapeutic approaches have led to modest improvement in survival outcomes, limited progress is achieved for the use of immunotherapeutics in this challenging cancer. Immune checkpoint inhibitors, thus far, single-agent or in combination, have not yielded significant improvement in survival outcomes except in mismatch repair-deficient pancreatic cancer. The tumor microenvironment of pancreatic cancer has been considered as an attractive target for over a decade based on preclinical studies that suggested it may adversely affect drug delivery and antitumor immunity. In this review article, we elaborate on the biology of pancreatic cancer microenvironment, its highly complicated interaction with cancer cells, and the immune system. We also discuss plausible explanations that led to the failure of immune checkpoint inhibitors as therapeutic agents and the potential impacts of pancreatic cancer stroma on these negative studies.

Precision medicine for gastrointestinal cancers: a conference report

As cancer management evolves into precision medicine national/international cancer meetings bring novel therapeutic approaches and potentially practice-changing results of clinical studies are presented. This year, the ASCO GI Symposium 2020 had also several updates from ongoing and finalized clinical trials. Although there were no groundbreaking results that impact the daily practice directly, several highly important data from ongoing studies were shared with the audience. In this report, the highlights of the ASCO GI Symposium 2020 are presented with a future perspective.

Safety and Efficacy of Immune Checkpoint Inhibitors in Patients With Cancer Living With HIV: A Perspective on Recent Progress and Future Needs

Recent studies have identified durable responses with the use of immune checkpoint inhibitors in patients with mismatch repair-deficient (MMR-D)/microsatellite instability-high (MSI-H) metastatic colorectal cancer (CRC). The dramatic improvement in clinical outcomes led to the US Food and Drug Administration approval of pembrolizumab, nivolumab, and nivolumab in combination with ipilimumab in metastatic patients with MSI-H/MMR-D CRC who previously experienced progression on cytotoxic therapies. In the clinical trials investigating these agents, HIV-seropositive patients were not included and therefore the clinical efficacy of these agents in patients with metastatic MSI-H/MMR-D CRC living with HIV is unclear. On the basis of growing evidence, immune checkpoint blockade therapies seem to be a safe approach in patients with well-controlled HIV infection. Research on immunotherapeutic approaches in patients living with HIV and cancer is an area of unmet medical need that can be addressed by clinical trial designs that are inclusive of patients with well-controlled seropositive HIV and trials that specifically evaluate immune therapies in patients living with HIV.

Clinical and molecular markers of immune checkpoint inhibitor (ICI) response in dMMR colorectal cancer (CRC) patients (pts)

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Background: ICIs induce durable responses in dMMR CRC patients. However, clinical and molecular biomarkers of response to ICIs have not been well-established. In this study, we investigated impact of specific MMR gene loss, BRAF V600E mutation and clinical characteristics of pts on clinical outcomes of ICIs. Methods: Pts were eligible if they had confirmed dMMR CRC by IHC or MSI-H by PCR and received ICIs between 01/01/2012 and 05/01/2019 at Winship Cancer Institute of Emory University, Mayo Clinic, Vanderbilt or Stanford University. Due to the functional dependency, the groups were categorized as protein loss of MLH1+PMS2 vs MSH2+MSH6. Log-rank test, Cox hazard model and Fisher’s exact test were used for survival outcomes, the best response and the distribution of variables among the subgroups. Results: A total of 66 pts with dMMR CRC were identified and BRAF status was available for 41 pts. ORRs in MLH1+PMS2 and MSH2+MSH6 groups were 72.9% and 56.5% respectively (P = 0.189). At 2 years, PFS rates were 55.6% and 78.2% for MLH1+PMS2 and MSH2+MSH6 groups respectively (P < 0.001). Pts with BRAF V600E mutations had significantly worse outcomes as compared to pts with wild-type BRAF (2-year PFS rate of 35.0% and 73.3% respectively; P < 0.001). Notably pts < 65 had better 2-year disease control rates when compared to > 65 (71.1% and 41.5% respectively; P < 0.001). We also observed worse 2-year PFS rates in pts with liver metastases (P = 0.014). CRC side and tumor volume did not impact 2-year PFS rates in our cohort. Conclusions: Our data suggest that pts with loss of function in MSH2+MSH6 may have better 2 year-PFS rates compared pts with MLH1+PMS2 even though ORR favored MLH1+PMS2 group suggesting that ORR may not reflect the durability of ICI response in dMMR CRC patients. Consistently, pts with BRAF V600E mutation which is associated with MLH1 promoter methylation had significantly worse 2-year PFS rates. Overall, our findings suggest that BRAFV600E mutation, the affected MMR proteins, pt age, and site of metastasis may impact durability of ICI response in dMMR CRC patients.

Immune checkpoint inhibitors for the treatment of MSI-H/MMR-D colorectal cancer and a perspective on resistance mechanisms

Metastatic colorectal cancer (CRC) with a mismatch repair-deficiency (MMR-D)/microsatellite instability-high (MSI-H) phenotype carries unique characteristics such as increased tumour mutational burden and tumour-infiltrating lymphocytes. Studies have shown a sustained clinical response to immune checkpoint inhibitors with dramatic clinical improvement in patients with MSI-H/MMR-D CRC. However, the observed response rates range between 30% and 50% suggesting the existence of intrinsic resistance mechanisms. Moreover, disease progression after an initial positive response to immune checkpoint inhibitor treatment points to acquired resistance mechanisms. In this review article, we discuss the clinical trials that established the efficacy of immune checkpoint inhibitors in patients with MSI-H/MMR-D CRC, consider biomarkers of the immune response and elaborate on potential mechanisms related to intrinsic and acquired resistance. We also provide a perspective on possible future therapeutic approaches that might improve clinical outcomes, particularly in patients with actionable resistance mechanisms.

Precision medicine for metastatic colorectal cancer: an evolving era

Introduction: Metastatic colorectal cancer (CRC) remains a dilemma for cancer researchers with an increasing incidence in the younger patient population. Until the last decade, limited therapeutic options were available for metastatic CRC patients leading to relatively poor clinical outcomes.Areas covered: With advances in genome sequencing technology and reductions in the cost of next-generation sequencing, molecular profiling has become more accessible for cancer researchers and clinical investigators, which has furthered our understanding of the molecular behavior of CRC. This progress has recently translated into significant advances in molecular-based therapeutics and led to the development of new target-specific agents in metastatic CRC patients. In this review article, we extensively elaborate on genomic alterations seen in CRC patients including, but not limited to, EGFR, MMR, BRAF, HER2, NTRKs, FGFR, BRCA1/2, PALB2, POLE, and POLD1 genes, all of which are potentially actionable by either an FDA-approved agent or in a clinical trial setting.Expert opinion: We strongly recommend molecular profiling in metastatic CRC patients during the early course of their disease, as this may provide therapeutic and prognostic information that can guide clinicians to practice precision medicine. Patients with potentially actionable genes should be considered for targeting agents based on molecular alterations.

Immune checkpoint inhibitors (ICIs) in gastrointestinal (GI) cancer: Immune-related adverse events (IRAEs) and efficacy

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Background: Despite the therapeutic promise of ICIs for patients (pts) with some advanced malignancies, they are FDA-approved for only a few GI cancer pts. In NSCLC, melanoma and urothelial carcinoma, there is emerging data that pts who experience IRAEs while on ICIs have improved outcomes compared with pts who do not. This association in GI cancer pts has not been reported. Methods: We retrospectively analyzed outcomes for metastatic GI cancer pts receiving ICIs for FDA-approved indications (later-line MSI-H tumors, 2nd line hepatocellular carcinoma (HCC), 3rd line PD-L1+ gastric (GA)/gastroesophageal junction (GEJ) adenocarcinoma), at Vanderbilt Ingram Cancer Center, Winship Cancer Institute and Stanford Cancer Institute. Our primary aim was to compare progression-free survival (PFS) and overall survival (OS) between pts who did and did not experience IRAEs. Secondary aims were comparison of these outcomes within pts who experienced IRAEs, by initial IRAE severity (Grade (G)3/G4 vs G1/G2) (CTCAE v5.0), time-to-onset (TTO) (≤ 6 weeks (w) vs > 6 w) and management (steroids vs drug cessation vs observation). PFS and OS were determined by Kaplan-Meier (KM) analysis; KM comparisons were done by the logrank test. Results: Between 1/2015-12/2018 61 GI cancer pts with HCC (28), colorectal cancer (27) and GA/GEJ cancer (6) were treated with ICIs; median age was 63 years. The majority (59) received single-agent nivolumab or pembrolizumab while minority (2) received nivolumab and ipilimumab; median time on ICIs was 5.9 months (mos). Twenty-four pts experienced initial IRAEs (6 G3/G4, 18 G1/G2); median TTO was 3.8 mos. Pts who experienced any IRAE had improvements in PFS and OS compared to those who did not (PFS: 32.4 mos (95% confidence interval (CI), 32.4-not reached (NR)) vs 4.8 mos (95% CI, 2.9-8.7), p = 0.0001; OS: 32.4 mos (95% CI, 32.4-NR) vs 8.5 mos (95% CI, 6-NR), p = 0.0036). Among pts who experienced IRAEs, PFS and OS differences between above-specified subgroups did not meet statistical significance. Conclusions: GI cancer pts who experienced IRAEs while on ICIs had marked improvements in PFS and OS compared to those who did not, suggesting the predictive potential for IRAEs as a clinical biomarker in this population.

Analysis of age, tumor-sidedness, and mismatch repair (MMR) genes with response to immune checkpoint inhibitors (ICIs) in MMR-deficient (dMMR) colorectal cancer (CRC) patients (pts): A multi-institutional study

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Background: ICIs induce durable responses in dMMR CRC pts with overall response rates (ORR) of 30-50%. Even though the loss of expression of any MMR gene predicts ICIs response, it is unknown if ORRs are similar across all MMR genes (MLH1, PMS2, MSH2, and MSH6). In this study, we analyzed the impact of each specific MMR gene loss and clinical characteristics of pts with best response to ICIs. Methods: Pts were eligible if they had confirmed dMMR CRC by IHC or microsatellite instability-high (MSI-H) by PCR, and received ICIs between 01/01/2012 and 10/01/2018 at Winship Cancer Institute of Emory University, Mayo Clinic or Vanderbilt University Medical Center. Due to the pattern of frequent concurrent loss and functional dependency, the groups were categorized as MLH1 ±PMS2 vs. MSH2 ±MSH6. Cox proportional hazard model and Fisher’s exact test were used for the best response and the distribution of variable among the subgroups. Results: A total of 45 pts with dMMR CRC were identified. ORRs in MLH1 ±PMS2 and MSH2 ±MSH6 groups were 68% and 57.1% respectively without statistical difference (Table). Pts with age < 50 and 50-65 years old had better ORRs compared to pts with age >65 (58.3%, 85.7% and 42.1% respectively, P=0.036). Left-sided tumors had a trend toward higher ORRs compared to right-sided tumors (83.3% vs 51.5% P=0.086). Gender and BRAF status were not predictors of response. BRAF mutations were more common in right-sided tumors (29.6% vs 11.1% respectively) and in older patients. Conclusions: Our data suggest that MSI-H CRC pts aged 50-65 treated with ICIs, have improved ORR compared to pts > 65; pts with left-sided tumors have a trend toward improved ORR compared to those with right sided tumors. [Table: see text]

Association of pancreatic cancer stem cells with tumor stroma type

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Background: Pancreatic ductal adenocarcinoma (PDA) is a heterogeneous disease with distinct stroma features. Cancer stem cells (CSC) in PDA may express CD44 (C) +/- Epithelial Specific Antigen (E). We investigated the relationship of CSC markers with tumor stroma and clinical outcomes in PDA patients (pts) who had surgical resection. Methods: Pts who underwent PDA resection with IRB #00-032/#06-107 consent between 01/2012-06/2014 at Memorial Sloan Kettering were identified. C and E immunohistochemical (IHC) expression scored as follow: 0, none; 1, 1%–10%; 2, 11%–50%; 3, 51%–80%; 4, 81%–100%. Staining intensity was scored as 0, none; 1, weak; 2, moderate; 3, strong. The total scores (0-12) were averaged and was considered positive when average score > median. Stroma was classified as loose, moderate and dense based on fibroblast content using H&E stain. Overall survival (OS) and relapse-free survival (RFS) were estimated using the Kaplan-Meier and compared by log-rank test; association between CSC markers and stroma type was assessed by Fisher`s exact test. Results: N = 93 PDA pts identified. PDA with C(+) E(-) had significantly higher loose stroma and PDA with C(-) E(+) and C(-) E(-) had more moderate and dense stroma (p = 0.0033). The number of PDA pts with dense, moderate, and loose stroma was: 11, 31, and 51 respectively. No local recurrence in pts with dense stroma observed and 8/11 had either lung or liver recurrence. Six of 31pts with loose stroma had a local recurrence and 13/31 pts had either liver or lung recurrence. No statistically significant difference in OS and RFS were observed among subgroups (P = 0.089). Median time from relapse to death was: 2, 11.5, 10,5 and months 7 in C+/E-, C-/E+, C+/E+, and C-/E- groups respectively. Conclusions: PDA CSCs appears to have an association with PDA stroma type. We also observed different recurrence patterns among stroma subgroups. Respecting small sample size, these data indicate CSCs may have an important role in stroma differentiation in PDA. CSC markers do not predict OS and RFS, however, resected PDA with C(+) E(-) may have more aggressive behavior following recurrence. [Table: see text]

Impact of genomic alterations (GAs) on outcomes and their distribution by age groups in metastatic colorectal cancer (mCRC) patients (pts)

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Background: Although clinical outcomes has substantially improved over the last decade, long term survival in mCRC remains rare. Molecular profiling (MP) of CRC is routinely conducted to identify potential therapeutic targets. The aim of this project is to evaluate the impact of uncommon GAs on outcomes and characterize their distribution by age. Methods: Pts were eligible if they had mCRC (synchronous or metachronous) and underwent MP between 01/2013 and 05/2018. GAs were obtained from Foundation Medicine reports. Clinical data were collected by trained personnel by detailed chart review. Multivariable survival analyses (MA) with Cox model were conducted for survival outcomes and Fisher’s exact test was used to assess the differences among age groups (< 45, 45-60, > 60). The study was reviewed by Institutional IRB ( IRB00097021 ). Results: 161 patients with mCRC had MP, and 159 of those patients had survival data. The most commonly detected GAs were APC (133/161, 82.6%) TP53 (128/161, 79.5%). In univariate analyses mutations in BRCA 1/2, RB1, SOX9, CDK8, FLT3, and IRS2 amplification were associated with worse survival outcomes. In MA, including initial stage of disease, GAs in BRCA1/2, RB1, FLT3, SOX9, and IRS2 remained statistically significant (Table). When we performed MA by age groups, mutations SOX9 in age group < 45 and BRCA1/2 in age group 45-60 were significant predictors of worse outcomes. We also compared the frequency of mutations among age groups and FAM123B was significantly more common in age group 45-60 (P = 0.038). Conclusions: Our data suggests that GAs in BRCA1/2, RB1, FLT3, SOX9, and IRS2 may predict worse outcomes in mCRC. Therapeutic approaches targeting these pathways should be investigated. Differences in distribution and prognostic significance of mutations were observed based on age. [Table: see text]

Pancreatic cancer microenvironment: a current dilemma

Pancreatic cancer is one of the leading causes of cancer-related death in the United States and survival outcomes remain dismal despite significant advances in molecular diagnostics and therapeutics in clinical practice. The microenvironment of pancreatic cancer carries unique features with increased desmoplastic reaction and is infiltrated by regulatory T cells and myeloid-derived suppressor cells which negatively impact the effector immune cells. Current evidence suggests that stellate cell-induced hypovascular stroma may have direct effects on aggressive behavior of pancreatic cancer. Preclinical studies suggested improvement in drug delivery to cancer cells with stroma modifying agents. However these findings so far have not been confirmed in clinical trials. In this article, we elaborate current-state-of-the science of the pancreatic cancer microenvironment and its impact on molecular behavior of cancer cells, chemotherapy resistance and druggability of stroma elements in combination with other agents to enhance the efficacy of therapeutic approaches.

Immunotherapy in pancreatic ductal adenocarcinoma: an emerging entity?

The genomic-plasticity of the immune system creates a broad immune repertoire engaged to tackle cancer cells. Promising clinical activity has been observed with several immune therapy strategies in solid tumors including melanoma, lung, kidney, and bladder cancers, albeit as yet immunotherapy-based treatment approaches in pancreatic ductal adenocarcinoma (PDAC) remain to have proven value. While translational and early clinical studies have demonstrated activation of antitumor immunity, most recent late-phase clinical trials have not confirmed the early promise in PDAC except in MSI-High PDAC patients. These results may in part be explained by multiple factors, including the poorly immunogenic nature of PDAC along with immune privilege, the complex tumor microenvironment, and the genetic plasticity of PDAC cells. These challenges have led to disappointments in the field, nonetheless they have also advanced our understanding that may tailor the future steps for immunotherapy for PDAC. Therefore, there is significant hope that progress is on the horizon.

Do pancreas cancer stem cells play crucial role in survival outcome?

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Background: Recent studies indicate that pancreatic cancer stem cells (CSC) may predict disease behavior and survival outcomes of pancreatic ductal adenocarcinomas (PDACs) patients (pts). Several CSC markers have been reported in PDAC (Fitzgerald, TL, 2014). We herein evaluated the impact of CSC markers including CD44 and Epithelial Specific Antigen (ESA) on survival outcome of PDAC pts who had liver or lung metastasis after initial surgical resection (IR). Methods: Clinicopathologic features and survival of 59 PDACs were analyzed. Pts with IRB approval, and whom had available primary tumor tissue, were included. All neoplasms were immuno labeled with CD44 and ESA. Staining intensity was scored as weak (1), moderate (2), strong (3), while the staining pattern was scored as: few (1), patchy (2), and diffuse (3). The expression for CD44 and ESA was accepted positive if total score ≥4. Time from relapse to death (TRD) was estimated using the Kaplan-Meier method censoring patients that were alive at the last follow up. Survival curves were compared using the log-rank test Results: Of 59 pts, 42 (71 %) had liver, 10 (17%) had lung and 7 (12%) had both liver and lung metastasis. M/F = 34/25; mean age = 64.2 (range, 34-90). Patients were subcategorized as follows; thirteen cases were CD44 (+)/ESA (-) (group1) and 13 were CD44 (-)/ESA (+) (group 2). Eight (61.5%) of group 1 tumors and 2 (15.3%) of group 2 were poorly differentiated. At last follow-up, except one with 63 months survival, all pts died of disease with 23.3 months (range, 3-67) median OS. No significant difference in TRD was observed between group 1 (6.9 months) and 2 (13.8 months) (p = 0.62). However, we observed group 1 tumors had worse OS (12 months) compared to group 2 (36 months). Conclusions:A worse outcome trend was observed for pts with CD44 (+)/ESA (-), albeit not statistically significant and likely limited by small numbers. Further studies are warranted to evaluate the robustness of this observation.

Oncogenic fingerprint of epidermal growth factor receptor pathway and emerging epidermal growth factor receptor blockade resistance in colorectal cancer

Epidermal growth factor receptor (EGFR) has been an attractive target for treatment of epithelial cancers, including colorectal cancer (CRC). Evidence from clinical trials indicates that cetuximab and panitumumab (anti-EGFR monoclonal antibodies) have clinical activity in patients with metastatic CRC. The discovery of intrinsic EGFR blockade resistance in Kirsten RAS (KRAS)-mutant patients led to the restriction of anti-EGFR antibodies to KRAS wild-type patients by Food and Drug Administration and European Medicine Agency. Studies have since focused on the evaluation of biomarkers to identify appropriate patient populations that may benefit from EGFR blockade. Accumulating evidence suggests that patients with mutations in EGFR downstream signaling pathways including KRAS, BRAF, PIK3CA and PTEN could be intrinsically resistant to EGFR blockade. Recent whole genome studies also suggest that dynamic alterations in signaling pathways downstream of EGFR leads to distinct oncogenic signatures and subclones which might have some impact on emerging resistance in KRAS wild-type patients. While anti-EGFR monoclonal antibodies have a clear potential in the management of a subset of patients with metastatic CRC, further studies are warranted to uncover exact mechanisms related to acquired resistance to EGFR blockade.

Gemcitabine-Related Pneumonitis in Pancreas Adenocarcinoma--An Infrequent Event: Elucidation of Risk Factors and Management Implications

BACKGROUND

Gemcitabine-related pneumonitis (GRP) has been reported relatively frequently for pancreas cancer in the literature; however, underlying risk factors and optimal management remain to be defined. We studied a cohort of patients with GRP and investigated potential predisposing factors in pancreatic cancer patients.

PATIENTS AND METHODS

A total 2440 patients at Memorial Sloan Kettering Cancer Center were identified between January 1, 2000, and December 31, 2012, and were screened for grade 2 or higher GRP in an institutional tumor registry and using an ICD billing code database. Demographic and clinical information was extracted by electronic chart review.

RESULTS

A total of 28 patients (1.1%) with GRP were identified. Incidence of grade 2, 3, and 4 reactions were 7 (25%), 18 (64%), and 3 (11%), respectively. No GRP-related mortality was observed. Twenty-one patients (75%) reported a history of cigarette smoking. Seventeen patients (61%) were alcohol users. Six patients (21%) were either regular or heavy drinkers. Most patients (93%) had either locally advanced or metastatic disease. Three patients (11%) underwent a diagnostic bronchoscopy, and in 1 patient a diagnosis of organizing pneumonia was established. Morbidity was significant; 3 patients (11%) required treatment in the intensive care unit. All hospitalized patients received steroid treatment.

CONCLUSION

GRP is relatively uncommon but incurs significant morbidity. Potential risk factors include advanced-stage disease, along with smoking and alcohol consumption and possibly underlying lung disease. We recommend a high level of clinical alertness regarding the diagnosis, early pulmonary referral, and cessation of gemcitabine on suspicion of GRP.

Retrospective evaluation of Middle Eastern patients (pts) with type II diabetes mellitus (DM) and colorectal cancer (CRC): Validation of metformin effect on overall survival (OS)

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Background: Epidemiologic data suggest that anti-DM medications may impact OS in CRC pts who have type 2 DM. Although type 2 DM and CRC are major health problems in the Middle East, little data exists on pts with both conditions from this region. Methods: Medical records from 1,835 CRC pts seen at King Hussein Cancer Center between 1/1/2004 and 12/31/2012 were evaluated for prevalence of type 2 DM; those with both conditions were evaluated for anti-diabetic therapy and treatment outcomes (OS and progression-free survival [PFS]). Results: 285 type 2 DM CRC patients were identified (prevalence 15.5%); 19 pts were censored as their anti-DM medications were not known. Median age of 266 pts analyzed was 62.1 years (± 8.9), M: F ratio 1.6:1, non-metformin (n = 109, 41%), metformin only (n = 43, 16%), metformin + insulin (n = 11, 4%), metformin + another oral agent (n = 104, 39%). Metformin use increased over time (19% in 2004 to 71% in 2012). Adjusting for age, gender, body mass index, and stage, type 2 DM pts treated with metformin had a 40% improvement in OS (hazard ratio 0.624, 95% confidence interval 0.44-0.97). Conclusions: These data support previous findings that metformin use in CRC pts with type 2 DM is associated with a superior PFS and OS. Contrary to previously published data there was a statistically significant OS benefit in stage IV pts, while the trend toward OS benefit in stage I-III pts was not statistically significant (see Table). This study was supported by the King Hussein Cancer Center/MD Anderson Sister Institution Network Fund. [Table: see text]

MD Anderson experience with off-study regorafenib in patients with advanced colorectal cancer

635

Background: Regorafenib was approved by the FDA on September 27, 2012 following the CORRECT trial demonstrating an overall survival (OS) benefit compared to placebo in pts with advanced treatment-refractory CRC (Grothey A. et al: Lancet. 2013;381:303-12). Little data exists regarding patient treatment outcomes outside of reported clinical trial data. Methods: Pts seen at MD Anderson Cancer Center with a diagnosis of gastrointestinal malignancies since October 1, 2012 were evaluated for regorafenib therapy; electronic clinic records were reviewed for pt treatment data, toxicity, and survival outcomes. Results: 61 pts were identified; 4 pts were determined to have GI malignancy other than CRC [appendiceal cancer (n=3) and duodenal cancer (n=1)] and were omitted from this analysis. Median age was 58 years (range 30.5-83.3), M:F 37:20 (65%:35%), KRAS non-mutant/ KRAS mutant 26/31 (46%:54%), BRAF mutant n=3 (5%); Median time from diagnosis of metastatic disease to initiation of regorafenib therapy was 27.7 months (range 5.9-112.3); 8 pts (14%) had enrolled in clinical trials prior to starting regorafenib. The initial starting dose was 160 mg (n= 38, 66.7%), 120mg (n=18, 31.5%), and 80mg (n=1, 1.8%) respectively. Dose reductions or interruptions were required in 25 pts (43.8%); 14 patients (24.5%) discontinued therapy due to toxicity. The most common grade 3 adverse event was hand-foot reaction (n=12; 21%). One pt initiated on 120 mg was able to tolerate dose escalation to 160mg. Seven pts (12.2%) had stable disease radiographically for more than 2 months and 2 had a confirmed partial response (3.5%). Median OS was 9.1 months (95% C.I. 5.3-12.8) and median time on regorafenib therapy was 2.2 months (range 0.2-10.3). Following regorafenib discontinuation 12 pts (21%) were enrolled on phase I trials. Conclusions: In this pt population palliative regorafenib therapy was associated with modest efficacy and significant toxicity. Dose reductions or interruptions were common (43.8%) even despite a large number of pts being initiated on a dose lower than the recommended initial dose (33.3%). Further studies may be required to determine the optimal tolerable dose in pts with advanced CRC.