Mismatch Repair Deficient Colorectal Cancer Research Articles

Efficacy and safety of neoadjuvant immune checkpoint inhibitors in patients with localized mismatch repair deficient colorectal cancer: A systematic review.

149 Background: Clinical data demonstrating remarkable anti-tumor activity of immune checkpoint inhibitors (ICI) in patients with mismatch repair deficient (dMMR) metastatic colorectal cancer (CRC) and preclinical data suggesting enhanced efficacy of ICIs in the neoadjuvant setting than in the adjuvant setting led to numerous studies with neoadjuvant ICI in various tumor types including in dMMR CRC. We performed a systematic literature review of the published studies reporting the efficacy and safety of neoadjuvant ICIs in patients with localized dMMR CRC. Methods: Medline and Embase were searched for eligible case reports, case series, and clinical trial reports. Eligibility criteria included: 1. patients aged 18 years or older, 2. localized dMMR CRC, and 3. received neoadjuvant therapy primarily with ICI. Patients receiving radiation or chemotherapy along with ICI were excluded. The systematic review was conducted according to the PRISMA harms guidelines. Results: The database search yielded 143 citations which were reviewed by 3 authors (UG, KV, and SC), and 14 citations fulfilled all criteria for inclusion. The analysis included 173 patients with colon cancer (CC) and 19 with rectal cancer (RC). Among the patients with CC, 41 (24 %) received single-agent programmed death 1 (PD-1) blocker, and 132 (76 %) received dual blockade with an anti-PD-1 agent plus an anti-cytotoxic T-lymphocyte antigen 4 (CTLA-4) agent. Resection was performed in 171/173 (99%) patients, and 117/171 (69%) achieved complete pathological response (pCR). After median follow-up ranging between 8 and 15 months, none of the patients experienced cancer relapse. Among patients with RC, 16/19 (84%) received a PD-1 blocker, and 3 (16%) received dual PD-1 plus CTLA-4 blocker. Complete clinical response (cCR) was reported in 14/19 (74%) patients, and of the 5 patients who underwent surgery, 4 (80%) achieved pCR. All patients remained progression-free after median follow-up ranging from 6 to 12 months. Cancer progression or death on neoadjuvant ICI was not reported in any studies with CC or RC patients, and only two studies reported grade 3+ toxicity in 3% of CC patients. Conclusions: Neoadjuvant therapy with ICIs results in a remarkably high rate of clinical and pathological tumor regression with negligible safety concerns in patients with dMMR localized CRC. Well-designed clinical trials with long-term follow-up are needed to evaluate the organ-sparing potential of neoadjuvant ICI therapy in patients with dMMR CRC.

Therapy with pembrolizumab in treatment-naïve patients with nonmetastatic, mismatch repair deficient colorectal cancer.

Therapy with immune checkpoint inhibitors (ICI) is effective in patients with metastatic mismatch-repair deficient (dMMR) colorectal cancer (CRC); however, data on treatment with neoadjuvant ICI in patients with locally advanced CRC are limited. From March 2019 to June 2020, five Danish oncological centers treated 10 patients with a treatment-naïve dMMR CRC with preoperative pembrolizumab, 9 with a nonmetastatic, unresectable colon cancer and 1 with a locally advanced rectum cancer. All 10 patients were evaluated regularly at a multidisciplinary team (MDT) meeting, and they all had a radical resection after a median of 8cycles (range 2-13) of pembrolizumab. A microscopic evaluation of the resected tumors revealed no remaining tumor cells in five patients, while five still had tumor cells present. The patients were given no additional therapy. No recurrences were reported after a median follow-up of 26 months (range 23-38.5months). Biopsies from Danish patients with CRC are routinely screened for dMMR proteins. In 2017, data from the Danish Colorectal Cancer Group showed that 19% (565/3000) of the patients with colon cancer and 1.5% (19/1279) of those with rectum cancer had an dMMR tumor. Among the patients with MMR determination, 26% (99/384) patients had a T4 dMMR colon cancer; thus, the 10 patients treated with neoadjuvant pembrolizumab comprised about 9% of the patients with a T4 dMMR colon cancer (9/99) and 5% of patients with dMMR rectal cancer (1/19). Therapy with pembrolizumab was feasible and effective. Larger prospective trials are needed to confirm our findings.

Neoadjuvant Immunotherapy Leads to Major Response and Low Recurrence in Localized Mismatch Repair–Deficient Colorectal Cancer

Our study aimed to evaluate the efficacy and feasibility of neoadjuvant anti-PD-1 treatment for localized mismatch repair-deficient (dMMR) colorectal cancer (CRC). The study cohort included patients with localized dMMR CRC who received PD-1 inhibitors as neoadjuvant therapy from 3 medical centers in Southern China. Main eligibility criteria included age between 18 and 75 years, ECOG performance status of 0 or 1, and receipt of ≥2 doses of PD-1 inhibitors. A total of 73 patients were included. Most of the tumors were locally advanced, including 19 (26.0%) T4a and 29 (39.7%) T4b. Most patients (79.5%) received PD-1 inhibitor monotherapy. Objective response per radiologic assessment was achieved in 62 (84.9%) patients, including 17 (23.3%) with complete response (CR) and 45 (61.6%) with partial response, with a median time to response of 9.6 weeks. Patients with T4a/4b disease had a similar response rate as those with T2-3 disease (84.0% vs 85.4%; P=.999). As of writing, a total of 50 patients have undergone surgery. Pathologic CR was achieved in most (57.1%) patients and remained high (59.5%) even among the 38 patients with T4a/4b disease. The 17 patients with CR did not undergo surgery and adopted a watch-and-wait strategy. After a median follow-up of 17.2 months (range, 3.4-45.1 months), the overall median recurrence-free and overall survivals were not reached. Among patients undergoing surgery or achieving CR, the 2-year tumor-specific disease-free and overall survival rates were both 100%. During neoadjuvant treatment, grade 3-4 adverse events occurred in 8 patients; 4 required acute intervention. Severe postoperative complications were recorded in 4 patients, 3 of whom required a second surgery. Neoadjuvant therapy with PD-1 blockade is highly effective for localized dMMR CRC, with an acceptable safety profile and low recurrence rate. This treatment holds promise for becoming the new standard of care for localized dMMR CRCs.

Tumor Ablation by Irreversible Electroporation Augments PD-1 Checkpoint Inhibitor Immunotherapy in Colon Adenocarcinoma

INTRODUCTION: Programmed Cell Death Protein 1 (PD-1) checkpoint inhibitors have recently been approved for microsatellite instability high (MSI-H) or mismatch repair deficient (dMMR) colorectal cancer (CRC). Response rates are promising in MSI-H-dMMR CRC but remain dismal for microsatellite-stable (MSS) or mismatch repair proficient (pMMR) CRC. >80% of CRCs are MSS-pMMR. Increasing tumor-infiltrating lymphocytes (TILs) may improve checkpoint inhibitor efficacy in CRC. New data suggest irreversible electroporation (IRE) therapy whereby electric pulses cause tumor necrosis and apoptosis; increase tumor-associated protein uptake by dendritic cells, subsequently boosting neoantigen presentation and TILs. We hypothesized that IRE combined with anti–PD-1 antibody, when compared with IRE or anti–PD-1 antibody alone, would increase survival, cause tumor regression by increasing TILs, and guard against secondary tumor challenge by increasing tumor antigen-specific CD8 T cells. METHODS: Using the MC38 cell line derived from murine colon adenocarcinoma, immunohistochemistry, and anti-CD8 antibodies, we evaluated antitumor immune responses in mice. RESULTS: IRE with anti–PD-1 antibody showed statistically significant survival, tumor regression, and increased TILs compared with IRE or anti–PD-1 antibody alone. Seventeen of 18 mice treated with IRE and anti–PD-1 antibody rejected a secondary tumor challenge. Conversely, IRE with anti–PD-1 antibody failed to protect against tumor rechallenge in mice that underwent CD8 T-cell depletion. Zero of 10 CD8 T-cell–depleted mice survived after secondary tumor challenge (Figure).FigureCONCLUSION: These data suggest IRE and anti–PD-1 antibody work in concert to bolster tumor-specific CD8 T-cell immune responses, serving as a pragmatic strategy for overcoming clinical challenges in checkpoint inhibitor immunotherapy for CRC.

Pembrolizumab in metastatic mismatch repair deficient colorectal cancer: the beginning of a journey into the land of immunotherapies for all cancers.

Pembrolizumab in metastatic mismatch repair deficient colorectal cancer: the beginning of a journey into the land of immunotherapies for all cancers.

Impact of Institutional Universal Microsatellite-Instability (MSI) Reflex Testing on Molecular Profiling Differences Between Younger and Older Patients with Colorectal Cancer

IntroductionDNA mismatch repair deficient (dMMR) or microsatellite instability-high (MSI-H) colorectal cancer (CRC) is found in about 15% of early-stage diseases and 5% of metastatic diseases. We reviewed a large, single-institutional database after implementation of universal reflex dMMR/MSI-H testing in CRC to compare profiles of younger (≤50) and older (>50) patients. Patients and MethodsBetween 2009 and 2017, all patients diagnosed with CRC at the University of Florida underwent reflex somatic tumor testing for dMMR by immunohistochemistry (MLH1, PMS2, MSH2, MSH6), MSI by PCR, and Next-Generation Sequencing. Statistical analysis was conducted with 2-sample comparison tests and logistic regression models. ResultsThere were 375 patients included in the final analysis. Patients were grouped as younger (ages ≤50 years-old; n = 80) or older (>50 years-old; n = 295). Compared to tumors from older patients, tumors from younger patients were less likely to be dMMR/MSI-H (12.5% vs. 21.4%, P = .013) and less likely to have a BRAF mutation (1.5% vs. 16.1%, P = .002). BRAF mutation status was highly associated with MMR status; BRAF-mutated tumors were 29.7 times more likely than BRAF-WT tumors to be dMMR/MSI-H (P = < .001, 95% CI 11.3-78.3). ConclusionsTumors of younger patients were less likely than tumors of older patients to have a dMMR/MSI-H or BRAF mutation. Universal MMR/MSI testing in our dataset identified a relatively large population of older patients with sporadic CRC who were eligible for immunotherapy.

PD-1 Blockade in Mismatch Repair–Deficient, Locally Advanced Rectal Cancer

BackgroundNeoadjuvant chemotherapy and radiation followed by surgical resection of the rectum is a standard treatment for locally advanced rectal cancer. A subset of rectal cancer is caused by a deficiency in mismatch repair. Because mismatch repair–deficient colorectal cancer is responsive to programmed death 1 (PD-1) blockade in the context of metastatic disease, it was hypothesized that checkpoint blockade could be effective in patients with mismatch repair–deficient, locally advanced rectal cancer.MethodsWe initiated a prospective phase 2 study in which single-agent dostarlimab, an anti–PD-1 monoclonal antibody, was administered every 3 weeks for 6 months in patients with mismatch repair–deficient stage II or III rectal adenocarcinoma. This treatment was to be followed by standard chemoradiotherapy and surgery. Patients who had a clinical complete response after completion of dostarlimab therapy would proceed without chemoradiotherapy and surgery. The primary end points are sustained clinical complete response 12 months after completion of dostarlimab therapy or pathological complete response after completion of dostarlimab therapy with or without chemoradiotherapy and overall response to neoadjuvant dostarlimab therapy with or without chemoradiotherapy.ResultsA total of 12 patients have completed treatment with dostarlimab and have undergone at least 6 months of follow-up. All 12 patients (100%; 95% confidence interval, 74 to 100) had a clinical complete response, with no evidence of tumor on magnetic resonance imaging, 18F-fluorodeoxyglucose–positron-emission tomography, endoscopic evaluation, digital rectal examination, or biopsy. At the time of this report, no patients had received chemoradiotherapy or undergone surgery, and no cases of progression or recurrence had been reported during follow-up (range, 6 to 25 months). No adverse events of grade 3 or higher have been reported.ConclusionsMismatch repair–deficient, locally advanced rectal cancer was highly sensitive to single-agent PD-1 blockade. Longer follow-up is needed to assess the duration of response. (Funded by the Simon and Eve Colin Foundation and others; ClinicalTrials.gov number, NCT04165772.)

Clinical actionability of triaging DNA mismatch repair deficient colorectal cancer from biopsy samples using deep learning.

SummaryBackgroundWe aimed to develop a deep learning (DL) model to predict DNA mismatch repair (MMR) status in colorectal cancers (CRC) based on hematoxylin and eosin-stained whole-slide images (WSIs) and assess its clinical applicability.MethodsThe DL model was developed and validated through three-fold cross validation using 441 WSIs from the Cancer Genome Atlas (TCGA) and externally validated using 78 WSIs from the Pathology AI Platform (PAIP), and 355 WSIs from surgical specimens and 341 WSIs from biopsy specimens of the Sun Yet-sun University Cancer Center (SYSUCC). Domain adaption and multiple instance learning (MIL) techniques were adopted for model development. The performance of the models was evaluated using the area under the receiver operating characteristic curve (AUROC). A dual-threshold strategy was also built from the surgical cohorts and validated in the biopsy cohort. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), F1-score, and the percentage of patients avoiding IHC testing were evaluated.FindingsThe MIL model achieved an AUROC of 0·8888±0·0357 in the TCGA-validation cohort, 0·8806±0·0232 in the PAIP cohort, 0·8457±0·0233 in the SYSUCC-surgical cohort, and 0·7679±0·0342 in the SYSUCC-biopsy cohort. A dual-threshold triage strategy was used to rule-in and rule-out dMMR patients with remaining uncertain patients recommended for further IHC testing, which kept sensitivity higher than 90% and specificity higher than 95% on deficient MMR patient triage from both the surgical and biopsy specimens, result in more than half of patients avoiding IHC based MMR testing.InterpretationA DL-based method that could directly predict CRC MMR status from WSIs was successfully developed, and a dual-threshold triage strategy was established to minimize the number of patients for further IHC testing.FundingThe study was funded by the National Natural Science Foundation of China (82073159, 81871971 and 81700576), the Natural Science Foundation of Guangdong Province (No. 2021A1515011792 and No.2022A1515012403) and Medical Scientific Research Foundation of Guangdong Province of China (No. A2020392).

Abstract 2030: A single-cell spatially resolved map of colorectal cancer identifies novel spatial relationships between cancer cells and the microenvironment

Abstract Understanding the tumor microenvironment (TME) requires more than just a catalog of cell types and gene programs. It is critical to see the spatial organization of the cells are and where they form multicellular interaction networks. Here we present a single-cell spatially resolved transcriptomic analysis of human mismatch repair deficient (MMRd) and proficient (MMRp) colorectal cancer (CRC) specimens. High tumor mutational burden MMRd tumors are known to have an immune response characterized by higher cytolytic T cell infiltrates compared to MMRp tumors, making them an ideal system for spatial single-cell profiling and understanding how the immune-driven programs differ between these tumors. MERFISH is a massively multiplexed single molecule imaging technology which can simultaneously capture and measure the quantity and distribution of hundreds to thousands of RNA species within single cells across a tissue1. We designed a MERFISH library of over 450 genes including genes important to proliferation, apoptosis, immune signaling, immune cell type pathways and other critical pathways in CRC. Patient samples, obtained commercially or through MGH, were hybridized with the designed MERFISH library and stained with a cell boundary marker to delineate cells across the tissue. We performed unsupervised clustering to identify cell types and we calculated spatial statistics to characterize how the cell type distribution varied between MMRd and MMRp tumors. We identified the cellular composition of each tumor, including immune and stromal cells, and the spatial distribution of these cell types. We were able to readily identify all cell types and states previously discovered by single-cell RNA sequencing2 in intact patient specimens, thus providing an accurate map of the cellular composition and spatial organization of these cells in the tumor microenvironment. We transformed these cell types into neighborhoods and discovered a highly organized spatial distribution of most cell types throughout the tumor. While spatial organization was observed in both MMRp and MMRd CRC we saw a significant shift in spatial organization between these tumor classifications notably in the immune population. Further, previously predicted multicellular interaction networks2 appeared as spatially organized structures in the tissue and were distinct in MMRd versus MMRp tumor specimens. Our data provide a richness of concrete hypotheses about which cells are working together, how these cells function cooperatively, and where these cells are located which will be critical in advancing therapy in these immunologically distinct types of colorectal cancer. These cancer maps are critical to truly understand the biology of CRC as well as identify avenues for the development of future therapies for CRC patients. Citation Format: Colles Price, Jonathan H. Chen, Karin Pelka, Sherry Chao, Michael Therrien, Timothy Wiggin, Nicolas Fernandez, Jiang He, George Emanuel, Genevieve Boland, Nir Hacohen. A single-cell spatially resolved map of colorectal cancer identifies novel spatial relationships between cancer cells and the microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2030.

Single agent PD-1 blockade as curative-intent treatment in mismatch repair deficient locally advanced rectal cancer.

LBA5 Background: Neoadjuvant chemotherapy and radiation followed by surgical resection of the rectum is a standard treatment for locally advanced rectal cancer. A subset of rectal cancer is mismatch repair deficient. Since mismatch repair deficient colorectal cancer is responsive to PD-1 blockade in the metastatic setting, we hypothesized that locally advanced mismatch repair deficient rectal cancer is sensitive to checkpoint blockade and may alter the requirements for chemoradiotherapy and surgery. Methods: We conducted a prospective phase II study in which single agent dostarlimab, an anti PD-1 monoclonal antibody, was administered every 3 weeks for 6 months in patients with mismatch repair deficient stage II and III rectal adenocarcinoma, to be followed by standard chemoradiation and surgery. Patients who achieved a clinical complete response were eligible for omission of chemoradiation and surgery. Results: Twelve patients initiated treatment and have at least 6 months of follow up. All 12 (100%, 95% CI:74%-100%) achieved a clinical complete response with no evidence of tumor on MRI, FDG-PET, endoscopic visualization, digital rectal exam, or biopsy, which satisfied the study’s co-primary endpoint. To date, no patients have required chemoradiation or surgery, and no cases of progression or recurrence have been noted during follow up (range 6-25 months). No serious adverse events &gt; grade 3 were observed. Conclusions: Mismatch repair deficient locally advanced rectal cancer is exceptionally sensitive to single agent PD-1 blockade. Longer follow up is needed to assess response duration. Clinical trial information: NCT04165772.

Patient-reported outcomes from the GARNET trial in patients with advanced or recurrent mismatch repair deficient (dMMR) colorectal cancer (CRC): A post hoc subgroup analysis.

3558 Background: Dostarlimab is a programmed death 1 (PD-1) inhibitor approved in the US as a monotherapy in patients (pts) with dMMR advanced/recurrent endometrial cancer that has progressed on or after prior treatment with a platinum-containing regimen or in pts with dMMR solid tumors that have progressed on or after prior treatment, with no satisfactory alternative treatment options. Here we report on patient-reported outcomes (PROs) in pts with dMMR CRC, a post hoc subgroup analysis. Methods: GARNET is a multicenter, open-label, single-arm phase 1 study. Cohort F enrolled pts with dMMR/microsatellite instability–high or POLε-mutated non-endometrial solid tumors. Pts with CRC must have received prior fluoropyrimidine, oxaliplatin, and irinotecan. Pts received 500 mg of IV dostarlimab Q3W for 4 cycles, then 1000 mg Q6W until discontinuation. PRO assessment, an exploratory endpoint, was measured using the EORTC-QLQ-C30. PROs were collected at baseline, at each dose cycle, and after discontinuation. Multi-item and item-level analyses were collected and scored; improvement was defined as mean change from baseline (directional change dependent on item). A 10-pt change in mean from baseline was considered clinically significant for the analysis. Results: PRO data at baseline were available for 96 pts with CRC who received ≥1 dose of dostarlimab. Improvements from baseline for quality of life (QOL) and most gastrointestinal symptom scales were observed and maintained from cycle 2 through 7 (Table). Stability in diarrhea was seen from cycles 2 through 7. Conclusions: PROs from the GARNET trial in pts with dMMR CRC show that QOL and disease-related gastrointestinal symptoms were improved or maintained while on dostarlimab treatment. These data, with the previously reported efficacy and safety profile, support the use of dostarlimab in pts with dMMR CRC. Clinical trial information: NCT02715284. [Table: see text]

Nivolumab with ipilimumab for MSI-H colorectal cancer with liver metastases.

e15556 Background: Immune checkpoint inhibitor (ICI) therapy has recently demonstrated durable clinical benefit in patients with advanced mismatch repair deficient (dMMR) colorectal cancer. The aim of this study was to test the combination of nivolumab and ipilimumab in microsatellite instability-high (MSI-H) colorectal cancer patients with oligometastatic liver disease. Methods: Twelve patients with MSI-H mCRC and one prior line of treatment for metastatic disease received nivolumab 3 mg/kg plus ipilimumab 1 mg/kg once every 3 weeks (four doses) followed by nivolumab 3 mg/kg once every 2 weeks until disease progression or discontinuation. The primary endpoint was objective response rate (ORR). Results: At baseline, the patients’ median age was 58 years (range, 51-67 years), and 40.7 % of patients were women. Sites of metastases included liver (89.8%), distant lymph nodes (43.6%), and lungs (9.2%). For all 12 patients (median follow-up was 8.2 months), ORR was 71% (95% CI 46.3–78.6). Of 12 patients enrolled, 4 patients (33%) achieved a partial response, and 5 patients (41%) achieved stable disease. Responses were consistent with the overall population across subgroups including age, Eastern Cooperative Oncology Group (ECOG) performance status, prior adjuvant/neoadjuvant therapy, and mutation status. Two patients (16%) had grade 3–4 treatment-related adverse events. Conclusions: Nivolumab plus ipilimumab demonstrated significant clinical benefit and was well tolerated in patients with MSI-H mCRC. Clinical evaluation of ICIs in first-line metastatic, adjuvant and neoadjuvant settings and in combination with other therapies are ongoing.

Neoadjuvant nivolumab, ipilimumab, and celecoxib in MMR-proficient and MMR-deficient colon cancers: Final clinical analysis of the NICHE study.

3511 Background: The combination of PD-1 and CTLA4 blockade has changed the treatment landscape for several cancer types. Although this treatment is highly effective in metastatic mismatch-repair deficient (dMMR) colorectal cancers, metastatic MMR-proficient (pMMR) tumors do not respond. The NICHE study was the first neoadjuvant immunotherapy study in colon cancer (CC) to show impressive responses in 100% of dMMR ( n= 20) and 27% of pMMR ( n= 15) CC. In contrast, pathologic response to neoadjuvant chemotherapy using standard of care folfox is approximately 5% in dMMR tumors. Here we present the final efficacy data for the original NICHE study cohorts. Methods: Patients with non-metastatic, resectable dMMR or pMMR CC were treated with a single dose of ipilimumab 1mg/kg and two doses of nivolumab 3mg/kg and underwent surgery within 6 weeks. In addition, patients with pMMR tumors were randomized to receive celecoxib. The primary endpoints were safety and feasibility, and secondary endpoints included pathologic response rate and disease-free survival in 30 patients with dMMR and 30 with pMMR tumors. Pathologic response was defined as 50% or less viable tumor rest (VTR), and major pathologic response (MPR) as &lt;10% VTR. Results: Thirty patients with pMMR and 32 with dMMR tumors were evaluable for the efficacy analyses. In the pMMR cohort, pathologic response was observed in 9/30 (30%, 95% CI 14-46%) patients, consisting of 7 MPR (including 3 pathologic complete responses {pCR}) and 2 partial responses. Four out of 9 pMMR responders had received celecoxib. Five patients received adjuvant chemotherapy. At a median follow-up of 25 months (IQR 12-35 months), 3 patients (all non-responders) in the pMMR group had disease recurrence. In the 32 patients with dMMR tumors, pathologic response was observed in 100% of patients, with 31/32 MPR (97%, 95% CI 91-100%) and one partial response. Pathologic complete response was observed in 22/32 (69%, 95% CI 53-85%) patients. None of the patients in the dMMR cohort had disease recurrence. Surgery was delayed in one patient with a pMMR tumor due to myositis. Grade 3 immune-related adverse events were observed in 12% of patients, consistent with our previous report on the primary endpoint. There were no grade 4 immune-related AEs nor unexpected surgical complications. Conclusions: These data confirm our previously published results of the NICHE study, with responses to neoadjuvant nivolumab plus ipilimumab in 30% of pMMR and 100% of dMMR CC in the completed original cohorts. Validation of the dMMR responses in a large group of dMMR patients is ongoing and has the potential to change current practice. Clinical trial information: NCT03026140.

The Alteration of T-Cell Heterogeneity and PD-L1 Colocalization During dMMR Colorectal Cancer Progression Defined by Multiplex Immunohistochemistry.

BackgroundImmune checkpoint inhibitors (ICIs) are quickly becoming key instruments in the treatment of mismatch repair-deficient (dMMR) colorectal cancers (CRCs). Despite their clinical value, ICIs have several limitations associated with their use. Only approximately 15% of all CRCs have a dMMR status, and the overall response rate of ICIs is approximately 40%. The mechanism of ICI resistance is not clear, and its study is limited by the lack of information available on the characterization of the immune microenvironment during the progression from early- to advanced-stage dMMR CRC.MethodsWe used multiplex immunohistochemistry (mIHC) with two panels, each containing five markers, to simultaneously analyze the proportions of immune microenvironment constituents in 59 patients with advanced-stage dMMR CRC and 24 patients with early-stage dMMR CRC. We detected immune cell–associated signatures in the epithelial and stromal regions and evaluated the predictive value of these immune molecules. Student’s t-tests, Mann–Whitney U tests, Cox proportional hazards regression modeling, univariate Cox modeling, and Kaplan–Meier estimation were used to analyze immune cell proportions and survival data.ResultsWe observed significantly higher proportions of CD8+ cytotoxic T cells (CD8+) (p = 0.001), CD8+ memory T cells (CD8+CD45RO+) (p = 0.032), and CD4+ regulatory T cells (CD4+FOXP3+) (p = 0.011) in the advanced-stage dMMR CRCs than in the early-stage dMMR CRCs. Furthermore, CD3+ T cells with PD-L1 colocalization (CD3+PD-L1+) (p = 0.043) and CD8+ T cells with PD-L1 colocalization (CD8+PD-L1+) (p = 0.005) were consistently more numerous in patients in the advanced stage than those in the early stage. Our analyses revealed that a high proportion of CD3+PD-1+ T cells was an independent prognostic factor of overall survival (OS) [hazard ratios (HR) = 9.6, p < 0.001] and disease-free survival (DFS) (HR = 3.7, p = 0.010) in patients in the advanced stage.ConclusionHigh numbers of CD8+ cytotoxic T cells and CD8+ memory T cells, which usually represent a cytotoxic function of the adaptive immune system and possibly enhanced inhibition factors, such as CD4+ regulatory T cells and PD-L1 colocalized T cells, were associated with the transformation of the immune microenvironment from the early stage to the advanced stage in dMMR CRCs. Furthermore, CD3+PD-1+ T cells are a prognostic factor for patients with dMMR.

A phase I/Ib study of regorafenib and nivolumab in mismatch repair proficient advanced refractory colorectal cancer

AimIn contrast to mismatch repair deficient (dMMR) colorectal cancer (CRC), mismatch repair proficient (pMMR) CRC is usually unresponsive to anti-PD-1 immunotherapy. Recent preclinical data suggest that regorafenib may enhance the antitumor activity of anti-PD-1 immunotherapy. However, the safety and efficacy of regorafenib plus nivolumab have not been established in patients with refractory metastatic pMMR CRC. This study aimed to evaluate the safety and efficacy of regorafenib plus nivolumab in metastatic pMMR metastatic CRC. MethodThis was a phase I/Ib study with standard 3 + 3 design plus dose expansion of the maximum tolerated dose (MTD) in patients with refractory metastatic pMMR CRC. Patients were treated with regorafenib combined with nivolumab. The primary end-points were dose-limiting toxicity (DLT) and MTD. The secondary end-points were objective response rate, safety and overall survival (OS). ResultsA total of 52 patients were enrolled, and 51 patients received at least one dose of treatment. Three patients experienced DLT (all grade 3 rash). MTD was regorafenib 80 mg and nivolumab 240 mg every 2 weeks. Most common grade 3/4 treatment-related adverse events were hypertension (16%), rash (10%) and anaemia (6%). Among 40 evaluable patients, four (10%) achieved partial response, including one unconfirmed response, 21 (53%) achieved stable disease, and disease control rate was 63%. The median progression-free survival and OS were 4.3 and 11.1 months, respectively. ConclusionsRegorafenib plus nivolumab appears to be well tolerated with limited anticancer activity in metastatic pMMR CRC. Trial RegistrationClinicalTrials.gov identifier: NCT03712943.

Comparative molecular genomic analyses of a spontaneous rhesus macaque model of mismatch repair-deficient colorectal cancer.

Colorectal cancer (CRC) remains the third most common cancer in the US with 15% of cases displaying Microsatellite Instability (MSI) secondary to Lynch Syndrome (LS) or somatic hypermethylation of the MLH1 promoter. A cohort of rhesus macaques from our institution developed spontaneous mismatch repair deficient (MMRd) CRC with a notable fraction harboring a pathogenic germline mutation in MLH1 (c.1029C<G, p.Tyr343Ter). Our study aimed to provide a detailed molecular characterization of rhesus CRC for cross-comparison with human MMRd CRC. We performed PCR-based MSI testing (n = 41), transcriptomics analysis (n = 35), reduced-representation bisulfite sequencing (RRBS) (n = 28), and MLH1 DNA methylation (n = 10) using next-generation sequencing (NGS) of rhesus CRC. Systems biology tools were used to perform gene set enrichment analysis (GSEA) for pathway discovery, consensus molecular subtyping (CMS), and somatic mutation profiling. Overall, the majority of rhesus tumors displayed high levels of MSI (MSI-H) and differential gene expression profiles that were consistent with known deregulated pathways in human CRC. DNA methylation analysis exposed differentially methylated patterns among MSI-H, MSI-L (MSI-low)/MSS (MS-stable) and LS tumors with MLH1 predominantly inactivated among sporadic MSI-H CRCs. The findings from this study support the use of rhesus macaques as an alternative animal model to mice to study carcinogenesis, develop immunotherapies and vaccines, and implement chemoprevention approaches relevant to sporadic MSI-H and LS CRC in humans.

Pathological response following neoadjuvant immunotherapy in mismatch repair-deficient/microsatellite instability-high locally advanced, non-metastatic colorectal cancer.

This case series demonstrates an excellent pathological response to neoadjuvant checkpoint inhibitor (CPI) therapy in patients with mismatch repair-deficient (dMMR) colorectal cancer, which has translated into exemplary short-term oncological outcomes. As well as validating the utility of neoadjuvant CPI therapy in dMMR colorectal cancer, it also opens the door to future study of limited resection in patients with tumours that would otherwise require multivisceral resection.

Systematic literature review and network meta-analysis of pembrolizumab versus other interventions for previously untreated, unresectable or metastatic, MSI-high or MMR-deficient CRC.

Aim: To compare pembrolizumab with competing interventions for previously untreated, unresectable or metastatic microsatellite instability-high or mismatch repair-deficient colorectal cancer. Method: Trials were identified via a systematic literature review and synthesized using a Bayesian network meta-analysis with time-varying hazard ratios (HRs). Results: Using intention-to-treat data, HRs for overall survival were generally in favor of pembrolizumab but not statistically significant; however, statistical significance was reached versus all comparators by month 16 when accounting for crossover. Estimated HRs for progression-free survival significantly favored pembrolizumab versus all comparators by month 12. Pembrolizumab was also superior to all comparators in terms of grade ≥3 adverse events. Conclusion: These analyses suggest that pembrolizumab is a highly efficacious and safe treatment in this population.

Current status, controversy and challenge in the neoadjuvant immunotherapy of colorectal cancer

Neoadjuvant therapy for colorectal cancer is widely used in rectal cancer, locally advanced colon cancer, and resectable metastatic and recurrent colorectal cancer. Mismatch repair deficient(dMMR) and microsatellite instablity-high (MSI-H) colorectal cancer patients who benefit from the efficacy of immune checkpoint inhibitors are expected to further improve the efficacy of traditional neoadjuvant therapy based on radiotherapy and chemotherapy. In this paper, the current status of immunotherapy (with emphasis on immune checkpoint inhibitors) is elucidated, and the opportunities of its application in neoadjuvant therapy are analyzed, including poor sensitivity of dMMR tumors to traditional therapy, good immune response of early tumors, predictable, manageable and controllable toxicity of immune checkpoint inhibitors. Colorectal cancer patients have growing and diverse needs to be met. Current controversies and challenges are analyzed, and the future directions are pointed out, including active screening of benefit groups, exploration of efficacy prediction markers, optimization of neoadjuvant immunotherapy models, attention to efficacy evaluation and new therapeutic endpoints. Neoadjuvant therapy should be effective, moderate and accurate based on the treatment target. It is the prerequisite and basis to guarantee medical safety and improve therapeutic effect to attach importance to the standardization and safety of clinical research and to pay attention to patients' interests and legal and ethical demands.

Neoadjuvant immunotherapy in microsatellite stability or mismatch repair proficient colorectal cancer

Immunotherapy has become an important treatment option for microsatellite instability-high (MSI-H) and mismatch repair deficient (dMMR) colorectal cancer. From late-line to first-line treatment, and even in neoadjuvant setting for early stage colorectal cancer, promising efficacy was observed with immunotherapy. In microsatellite stability (MSS) or mismatch repair proficient (pMMR) colorectal cancer, the researches of neoadjuvant immunotherapy have been conducted constantly. This paper focuses on the recent researches and progress of neoadjuvant immunotherapy for MSS or pMMR colorectal cancer. Neoadjuvant immunotherapy alone led to a good pathological response in a subset of patients. Studies of induction or consolidation immunotherapy before or after neoadjuvant chemoradiotherapy or concurrent immunotherapy during radiotherapy showed higher pathological complete remission (pCR) rates as compared to standard chemoradiotherapy. Studies on sequential dual immunotherapy after radiochemotherapy and targeted therapy combined with neoadjuvant immunotherapy are ongoing. At present, most of these are pilot studies with small sample size. More researches and long-term follow-up are needed to prove the efficacy of neoadjuvant immunotherapy in MSS or pMMR colorectal cancer.