Nivolumab + low-dose ipilimumab in previously treated patients with microsatellite instability-high/mismatch repair-deficient metastatic colorectal cancer: 4-year follow-up from CheckMate 142

The trends and hotspots of immunotherapy for metastatic colorectal cancer from 2013 to 2022: A bibliometric and visual analysis

An increasing body of research indicates that immunotherapy has demonstrated substantial effectiveness in the realm of metastatic colorectal cancer(mCRC), especially among patients with deficient mismatch repair (dMMR) or microsatellite instability-high (MSI-H) (dMMR/MSI-H mCRC). This study constitutes the inaugural bibliometric and visual analysis of immunotherapy related to mCRC during the last decade. Between 2013 and the conclusion of 2022, we screened 306 articles from Web of Science and subjected them to analysis using CiteSpace and VOSviewer. The United States stood out as the primary contributor in this area, representing 33.33% of the publications, with China following closely at 24.51%. The most prolific institution has the lowest average citation rate. Sorbonne University were the most highly cited institutions. Notably, Frontiers In Oncology published the largest quantity of articles. Andre, Thierry, and Overman, Michael J. were prominent authors known for their prolific output and the high citation rates of their work. The focus areas in this field encompass "tumor microenvironment," "liver metastasis," "tumor-associated macrophages," "combination therapy" and "gut microbiota." Some keywords offer promise as potential biomarkers for evaluating the effectiveness of immunotherapeutic interventions.

ELISA assay for the quantification of ipilimumab in human serum, plasma, milk, and cerebrospinal fluid

Ipilimumab is an immune checkpoint inhibitor of the cytotoxic T-lymphocyte-associated protein 4 (CTLA-4). Ipilimumab has become part of the standard of care for different types of cancer. The efficacy of these treatments is limited due to immune-related toxicity and high economic costs. Dose rationalization studies based on pharmacokinetic data may help to address these limitations. For this purpose, more sensitive analytical methods are needed. We report the development and validation of the first enzyme-linked immunosorbent assay (ELISA) for sensitive determination of ipilimumab concentrations in human serum, plasma, cerebrospinal fluid (CSF), and milk. Our assay is based on the specific capture of ipilimumab by immobilized CTLA-4. The lower limit of quantifications of ipilimumab in serum, plasma, and milk are 50 ng/mL and 10 ng/mL in CSF. The ELISA method showed long-term storage stability for at least one year at -80°C and was successfully cross-validated with ultraperformance liquid chromatography coupled with tandem mass spectrometry. The ELISA method is reliable, relatively inexpensive, and can be used in serum, plasma, CSF, and milk from patients treated with ipilimumab, as evidenced by the analysis of real clinical samples.

Improving the efficiency of immune checkpoint inhibitors for metastatic pMMR/MSS colorectal cancer: Options and strategies

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment and been extensively used for patients with metastastic colorectal cancer (mCRC), especially those harboring deficient mismatch repair/ microsatellite instability (dMMR/MSI). However, the majority of mCRC are classified as proficient mismatch repair/microsatellite stability(pMMR/MSS) type characterized by a cold immune microenvironment, rendering them generally unresponsive to ICIs. How to improve the efficacy of ICIs for these patients is an important issue to be solved. On the one hand, it is urgent to discover the predictive biomarkers and clinical characteristics associated with effectiveness and expand the subset of pMMR/MSS mCRC patients who benefit from ICIs. Additionally, combined strategies are being explored to modulate the immune microenvironment of pMMR/MSS CRC and facilitate the conversion of cold tumors into hot tumors. In this review, we have focused on the recent advancements in the predictive biomarkers and combination therapeutic strategies with ICIs for pMMR/MSS mCRC.

Colorectal cancer

Despite decreased incidence rates in average-age onset patients in high-income economies, colorectal cancer is the third most diagnosed cancer in the world, with increasing rates in emerging economies. Furthermore, early onset colorectal cancer (age ≤50 years) is of increasing concern globally. Over the past decade, research advances have increased biological knowledge, treatment options, and overall survival rates. The increase in life expectancy is attributed to an increase in effective systemic therapy, improved treatment selection, and expanded locoregional surgical options. Ongoing developments are focused on the role of sphincter preservation, precision oncology for molecular alterations, use of circulating tumour DNA, analysis of the gut microbiome, as well as the role of locoregional strategies for colorectal cancer liver metastases. This overview is to provide a general multidisciplinary perspective of clinical advances in colorectal cancer.

Investigating the therapeutic promise of Drug-Repurposed-Loaded Nanocarriers: A pioneering strategy in advancing colorectal cancer treatment

Globally, colorectal cancer is a major health problem that ranks in third place in terms of occurrences and second in terms of mortality worldwide. New cases increase annually, with the absence of effective therapies, especially for metastatic colorectal cancer, emphasizing the need for novel therapeutic approaches. Although conventional treatments are commonly used in oncotherapy, their success rate is low, which leads to the exploration of novel technologies. Recent efforts have focused on developing safe and efficient cancer nanocarriers. With their nanoscale properties, nanocarriers have the potential to utilize internal metabolic modifications amid cancer cells and healthy cells. Drug repurposing is an emerging strategy in cancer management as it is a faster, cheaper, and safer method than conventional drug development. However, most repurposed drugs are characterized by low-key pharmacokinetic characteristics, such as poor aqueous solubility, permeability, retention, and bioavailability. Nanoparticle formulations and delivery have expanded over the past few decades, creating opportunities for drug repurposing and promises as an advanced cancer modality. This review provides a concise and updated overview of colorectal cancer treatment regimens and their therapeutic limitations. Furthermore, the chemotherapeutic effect of various FDA-approved medications, including statins, non-steroidal anti-inflammatory drugs, antidiabetic and anthelmintic agents, and their significance in colorectal cancer management. Along with the role of various nanocarrier systems in achieving the desired therapeutic outcomes of employing these redefined drugs.

Long-term survivals of immune checkpoint inhibitors as neoadjuvant and adjuvant therapy in dMMR/MSI-H colorectal and gastric cancers

BACKGROUND

The long-term survival benefit of immune checkpoint inhibitors (ICIs) in neoadjuvant and adjuvant settings is unclear for colorectal cancers (CRC) and gastric cancers (GC) with deficiency of mismatch repair (dMMR) or microsatellite instability-high (MSI-H).

METHODS

This retrospective study enrolled patients with dMMR/MSI-H CRC and GC who received at least one dose of neoadjuvant ICIs (neoadjuvant cohort, NAC) or adjuvant ICIs (adjuvant cohort, AC) at 17 centers in China. Patients with stage IV disease were also eligible if all tumor lesions were radically resectable.

RESULTS

In NAC (n = 124), objective response rates were 75.7% and 55.4%, respectively, in CRC and GC, and pathological complete response rates were 73.4% and 47.7%, respectively. The 3-year disease-free survival (DFS) and overall survival (OS) rates were 96% (95%CI 90-100%) and 100% for CRC (median follow-up [mFU] 29.4 months), respectively, and were 84% (72-96%) and 93% (85-100%) for GC (mFU 33.0 months), respectively. In AC (n = 48), the 3-year DFS and OS rates were 94% (84-100%) and 100% for CRC (mFU 35.5 months), respectively, and were 92% (82-100%) and 96% (88-100%) for GC (mFU 40.4 months), respectively. Among the seven patients with distant relapse, four received dual blockade of PD1 and CTLA4 combined with or without chemo- and targeted drugs, with three partial response and one progressive disease.

CONCLUSION

With a relatively long follow-up, this study demonstrated that neoadjuvant and adjuvant ICIs might be both associated with promising DFS and OS in dMMR/MSI-H CRC and GC, which should be confirmed in further randomized clinical trials.

Non-operative management after immune checkpoint inhibitors for early-stage, dMMR/MSI-H gastrointestinal cancers

Surgery is a standard treatment for early-stage gastrointestinal cancers, often preceded by neoadjuvant chemo(radio)therapy or followed by adjuvant therapy. While leading to cure in a proportion of patients, it has some drawbacks such as intra/post-operative complications, mutilation and life-long functional sequelae. Further to the unprecedented efficacy data from studies of immune checkpoint inhibitors for advanced mismatch repair deficient/microsatellite instable (dMMR/MSI-H) tumours, a strong interest has recently emerged for the investigation of such agents in the neoadjuvant setting. Although limited by the exploratory design and small sample size, trials of neoadjuvant immune checkpoint inhibitors for early-stage dMMR/MSI-H gastrointestinal cancers have consistently reported complete response rates ranging from 70 % to 100 %. As a result, the question has arisen as to whether surgery is still needed or organ-preserving strategies should be offered to this especially immuno-sensitive population. In this article, we discuss the available evidence for neoadjuvant immune checkpoint inhibitors in dMMR/MSI-H gastrointestinal cancers and analyse opportunities and challenges to the implementation of non-operative management approaches in this setting.

Rapamycin circumvents anti PD-1 therapy resistance in colorectal cancer by reducing PD-L1 expression and optimizing the tumor microenvironment

The unresectable or postoperative recurrence of advanced metastatic colorectal cancer (CRC) is the difficulty of its clinical management, and pharmacological therapy is the main source of benefit. Immune checkpoint inhibitors are therapeutic options but are effective in approximately 5 % of patients with deficient mismatch repair (MMR)/microsatellite instability CRC and are ineffective in patients with MMR-proficient (pMMR)/microsatellite stable (MSS) CRCs, which may be associated with the tumor microenvironment (TME). Here, we propose a new combination strategy and evaluate the efficacy of rapamycin (Rapa) combined with anti-PD-1 (αPD-1) in CT26 tumor-bearing mice, azoxymethane (AOM)/dextran sodium sulfate (DSS) inflammation-associated CRC mice, CT26-Luc tumor-bearing mice with postoperative recurrence, and CT26 liver metastasis mice. The results revealed that Rapa improved the therapeutic effect of αPD-1 and effectively inhibited colorectal carcinogenesis, postoperative recurrence, and liver metastasis. Mechanistically, Rapa improved the anticancer effect of αPD-1, associated with Rapa reprograming of the immunosuppressive TME. Rapa effectively depleted α-SMA+ cancer-associated fibroblasts and degraded collagen in the tumor tissue, increasing T lymphocyte infiltration into the tumor tissue. Rapa induced the downregulation of programed cell death 1 ligand 1 (PD-L1) protein and transcript levels in CT26 cells, which may be associated with the inhibition of the mTOR/P70S6K signaling axis. Furthermore, co-culture of tumor cells and CD8+ T lymphocytes demonstrated that Rapa-induced PD-L1 downregulation in tumor cells increased spleen-derived CD8+ T lymphocyte activation. Therefore, Rapa improves the anti-tumor effect of αPD-1 in CRCs, providing new ideas for its use to improve combinatorial strategies for anti-PD-1 immunotherapy.

Cadherin 17 Nanobody-Mediated Near-Infrared-II Fluorescence Imaging-Guided Surgery and Immunotoxin Delivery for Colorectal Cancer

Surgery and targeted therapy are of equal importance for colorectal cancer (CRC) treatment. However, complete CRC tumor resection remains challenging, and new targeted agents are also needed for efficient CRC treatment. Cadherin 17 (CDH17) is a membrane protein that is highly expressed in CRC and, therefore, is an ideal target for imaging-guided surgery and therapeutics. This study utilizes CDH17 nanobody (E8-Nb) with the near-infrared (NIR) fluorescent dye IRDye800CW to construct a NIR-II fluorescent probe, E8-Nb-IR800CW, and a Pseudomonas exotoxin (PE)-based immunotoxin, E8-Nb-PE38, to evaluate their performance for CRC imaging, imaging-guided precise tumor excision, and antitumor effects. Our results show that E8-Nb-IR800CW efficiently recognizes CDH17 in CRC cells and tumor tissues, produces high-quality NIR-II images for CRC tumors, and enables precise tumor removal guided by NIR-II imaging. Additionally, fluorescent imaging confirms the targeting ability and specificity of the immunotoxin toward CDH17-positive tumors, providing the direct visible evidence for immunotoxin therapy. E8-Nb-PE38 immunotoxin markedly delays the growth of CRC through the induction of apoptosis and immunogenic cell death (ICD) in multiple CRC tumor models. Furthermore, E8-Nb-PE38 combined with 5-FU exerts synergistically antitumor effects and extends survival. This study highlights CDH17 as a promising target for CRC imaging, imaging-guided surgery, and drug delivery. Nanobodies targeting CDH17 hold great potential to construct NIR-II fluorescent probes for surgery navigation, and PE-based toxins fused with CDH17 nanobodies represent a novel therapeutic strategy for CRC treatment. Further investigation is warranted to validate these findings for potential clinical translation.

Immunotherapy in the neoadjuvant treatment of gastrointestinal tumors: is the time ripe?

Immune checkpoint inhibitors (ICIs) revolutionized the management of mismatch repair-deficient (dMMR)/microsatellite instability-high (MSI-H) gastrointestinal (GI) cancers. Based on notable results observed in the metastatic setting, several clinical trials investigated ICIs as neoadjuvant treatment (NAT) for localized dMMR/MSI-H GI cancers, achieving striking results in terms of clinical and pathological responses and creating the opportunity to spare patients from neoadjuvant chemotherapy and/or radiotherapy and even surgical resection. Nevertheless, these impressive findings are mainly derived from small proof of concept phase II studies and there are still several open questions to address. Moreover, dMMR/MSI-H represents a limited subgroup accounting for less than 10% of GI cancers. Consequently, many efforts have been produced to investigate neoadjuvant ICIs also in mismatch repair-proficient/microsatellite stable (MSS) cancers, considering the potential synergistic effect in combining immune-targeted agents with standard therapies such as chemo and/or radiotherapy. However, results for combining ICIs to the standard of care in the unselected population are still unsatisfactory, without improvements in event-free survival in esophago-gastric adenocarcinoma for the addition of pembrolizumab to chemotherapy, and sometimes limited benefit in patients with locally advanced rectal cancer. Therefore, a major challenge will be to identify among the heterogenous spectrum of this disease, those patients that could take advantage of neoadjuvant immunotherapy and deliver the most effective treatment. In this review we discuss the rationale of NAT in GI malignancies, summarize the available evidence regarding the completed trials that evaluated this treatment strategy in both MSI-H and MSS tumors. Finally, we discuss ongoing studies and future perspectives to render neoadjuvant immunotherapy another arrow in the quiver for the treatment of locally advanced GI tumors.

PD-1 blockade plus COX inhibitors in dMMR metastatic colorectal cancer: Clinical, genomic, and immunologic analyses from the PCOX trial

BACKGROUND

Approximately 20% of patients with DNA mismatch repair deficiency (dMMR) metastatic colorectal cancer do not respond to anti-programmed death-1 (PD-1) ligand therapy, and baseline biomarkers of response are lacking.

METHODS

We conducted a phase 2 study to evaluate the efficacy of cyclooxygenase (COX) inhibitors in combination with anti-PD-1 therapy in patients with dMMR metastatic colorectal cancer. The primary endpoint was objective response rate. The secondary endpoints included progression-free survival (PFS), overall survival (OS), disease control rate, duration of response, and safety.

FINDINGS

A total of 30 patients were enrolled, and the objective response rate was 73.3%, meeting the predefined endpoint of 68%. The median PFS and median OS were not reached at a median follow-up period of 50.8 months. Disease control was achieved in 28 patients (93.3%). The median duration of response was not reached. The combination was well tolerated. Multiomics analysis revealed that the antigen processing and presentation pathway was positively associated with treatment response and PFS. Higher TAPBP expression was predictive of better PFS (log-rank p = 0.003), and this prognostic significance was confirmed in an immunotherapy validation cohort.

CONCLUSIONS

Thus, COX inhibitors combined with PD-1 blockade may be effective and safe treatment options for patients with dMMR metastatic colorectal cancer, and TAPBP may serve as a biomarker for immune checkpoint inhibitor therapy (this study was registered at ClinicalTrials.gov: NCT03638297).

FUNDING

Funded by the National Natural Science Foundation of China (81974369) and the program of Guangdong Provincial Clinical Research Center for Digestive Diseases (2020B1111170004).

Metastatic colorectal cancer- third line therapy and beyond

INTRODUCTION

The outcome of patients with metastatic colorectal cancer (mCRC) has improved significantly in the last few decades. Metastatic colorectal cancer is a highly heterogenous cancer. Beyond second line chemotherapy, treatment decisions are often based on molecular testing.

METHOD

In this narrative review, we provide a comprehensive summary of data from key clinical trials and discuss how to integrate these agents into the current treatment landscape of metastatic colorectal cancer.

EXPERT OPINION

In the era of precision medicine, molecular testing plays an increasingly important role in the management of mCRC. Efforts need to be made to target treatment based on molecular test results.

Imaging-guided prognostic score-based approach to assess the benefits of combotherapy versus monotherapy with immune checkpoint inhibitors in metastatic MSI-H colorectal cancer patients

BACKGROUND

This retrospective study determined survival responses to immune checkpoint inhibitors (ICIs), comparing mono- (mono) and combo-immunotherapy (combo) in patients with microsatellite instability-high (MSI-H) metastatic colorectal cancer (mCRC) by analyzing quantitative imaging data and clinical factors.

METHODS

One hundred fifty patients were included from two centers and divided into training (n = 105) and validation (n = 45) cohorts. Radiologists manually annotated chest-abdomen-pelvis computed tomography and calculated tumor burden. Progression-free survival (PFS) was assessed, and variables were selected through Recursive Feature Elimination. Cutoff values were determined using maximally selected rank statistics to binarize features, forming a risk score with hazard ratio-derived weights.

RESULTS

In total, 2258 lesions were annotated with excellent reproducibility. Key variables in the training cohort included: total tumor volume (cutoff: 73 cm3), lesion count (cutoff: 20), age (cutoff: 60) and the presence of peritoneal carcinomatosis. Their respective weights were 1.13, 0.96, 0.91, and 0.38, resulting in a risk score cutoff of 1.36. Low-score patients showed similar overall survival and PFS regardless of treatment, while those with a high-score had significantly worse survivals with mono vs combo (P = 0.004 and P = 0.0001). In the validation set, low-score patients exhibited no significant difference in overall survival and PFS with mono or combo. However, patients with a high-score had worse PFS with mono (P = 0.046).

CONCLUSIONS

A score based on total tumor volume, lesion count, the presence of peritoneal carcinomatosis, and age can guide MSI-H mCRC treatment decisions, allowing oncologists to identify suitable candidates for mono and combo ICI therapies.

Bifidobacterium modulation of tumor immunotherapy and its mechanism

The advent of tumor immunotherapy in patients has revolutionized the treatment of tumors and significantly improved survival rates for a wide range of tumors. However, the full therapeutic potential of immune checkpoint inhibitors (ICIs) has yet to be realized, as not all patients have a lasting survival benefit from them, and a significant proportion of patients show primary or acquired resistance to immunotherapy. Bifidobacterium is one of the most common probiotics, and its antitumor and immunomodulatory effects have been demonstrated in recent years, but its immunomodulatory effects in tumors, especially on ICIs and in combination, have not been extensively studied in clinical practice, and its effects on the immune system and the mechanisms that modulate immunotherapy are largely unknown. Therefore, this review will focus on the immunomodulatory effects of Bifidobacteria in malignancies and the possible mechanisms of action of Bifidobacteria on immunotherapy in the hope of providing a basis for further research and better application of Bifidobacteria in clinical practice.

Effectiveness of immune checkpoint inhibitors in combination with tyrosine kinase inhibitors in patients with advanced or metastatic colorectal carcinoma with either mismatch repair proficient or metastatic microsatellite stable disease: A systematic review and meta‑analysis

Immune checkpoint inhibitors (ICIs) have limited efficacy in mismatch repair proficient (pMMR) or metastatic microsatellite stable (MSS) advanced or metastatic colorectal cancer (mCRC). ICIs, in conjunction with tyrosine kinase inhibitors (TKIs) possessing anti-angiogenic properties, serve as a potential strategy for circumventing the resistance exhibited by MSS or pMMR mCRC to immunotherapeutic interventions. The present study aimed to evaluate efficacy and safety of ICIs + TKIs and provide a reference for the treatment of CRC. The present systematic review and meta-analysis was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. PubMed, Embase, Cochrane, Web of Science and ClinicalTrials.gov databases were screened from January 1, 2003 to July 28, 2023. A total of 14 studies were included in qualitative and quantitative analyses, with a total of 819 patients enrolled. The Newcastle-Ottawa scale scores of the 14 cohort studies included were ≥7, indicating they were of a high quality. The objective response rate (ORR) of ICIs + TKIs was 14% [95% confidence interval (CI), 0.08-0.24; P=0.132] in patients with advanced or metastatic MSS/pMMR CRC. The disease control rate (DCR) was 65% (95% CI, 0.58-0.74; P<0.0001). The overall incidence of adverse events of varying severity linked to combination of ICIs and TKIs in patients with advanced or metastatic MSS/pMMR CRC was 64% (95% CI, 0.52-0.78; P<0.0001). The incidence of grade ≥3 adverse reactions was 24% (95% CI, 0.14-0.4; P<0.0001). The sensitivity analysis indicated that the exclusion of individual studies did not yield statistically significant variations in combined analysis results. Based on the examination of publication bias, ORR and DCR, Begg's and Egger's tests had P-values of 0.114 and 0.395, respectively. Overall publication bias overall was absent in the Begg's funnel plot, as there was no apparent asymmetry. Nonetheless, the P-values of the Egger's and Begg's tests for adverse reactions and adverse reactions grade ≥3 were P=0.008 and P=0.048, respectively. The asymmetry of the Begg's funnel plots was evident, suggesting the presence of potential publication bias regarding adverse event results. In conclusion, the combination of ICIs and TKIs demonstrates a favorable effectiveness and notable safety profile in the management of patients with advanced or metastatic MSS/pMMR CRC.

The Expression Patterns of Immune Checkpoint Molecules in Colorectal Cancer: An Analysis Based on Microsatellite Status

Recently, immunotherapy has arisen as a novel treatment approach for patients with colorectal cancer (CRC), but the effectiveness of immunotherapy varies in these patients. We hypothesized that immune checkpoint molecules (ICMs), which are the targets of immunotherapy, are often exhibited concomitantly. Our objective was to investigate the patterns of ICM expression in patients with CRC and the differences in ICM expression based on microsatellite instability status. The immunohistochemical expression of programmed cell death protein 1 (PD-1), programmed cell death ligand 1 (PD-L1), T cell immunoglobulin and mucin-domain containing-3 (TIM-3), and lymphocyte-activation gene 3 (LAG-3) in the tumor center and periphery was assessed in patients with non-metastatic colorectal cancer. We enrolled 83 patients with CRC: a total of 40 microsatellite-stable (MSS) and 43 microsatellite-instability-high (MSI-H) cancer patients. PD-L1 was more frequently expressed in the tumor center in the MSI-H patients with than that in the MSS patients (18 [41.9%] vs. 3 [7.5%], respectively; p < 0.001), and the same trend was observed for TIM-3 expression (30 [69.8%] vs. 19 [47.5%], respectively; p = 0.047). The concomitant expression of two or more ICMs was more frequently observed than no expression or the expression of a single molecule in both the MSS and MSI-H groups; a total of 34 (79.7%) patients with MSI-H cancer and 23 (57.5%) with MSS cancer showed ICM expression at the tumor center, whereas 34 (79.7%) patients with MSI-H cancer and 22 (55%) with MSS cancer showed expression at the tumor periphery. Patients with the genetic characteristics of MSI-H cancer showed higher expression levels of ICMs than those in patients with MSS cancer, and predominantly, two or more ICMs were concurrently expressed. Our findings highlight the potential efficacy of the dual-blockade approach in immunotherapy, particularly in patients with MSI-H CRC.

Prognostic and predictive role of immune microenvironment in colorectal cancer

Colorectal cancer (CRC) represents a molecularly heterogeneous disease and one of the most frequent causes of cancer-related death worldwide. The traditional classification of CRC is based on pathomorphological and molecular characteristics of tumor cells (mucinous, ring-cell carcinomas, etc.), analysis of mechanisms of carcinogenesis involved (chromosomal instability, microsatellite instability, CpG island methylator phenotype) and mutational statuses of commonly altered genes (KRAS, NRAS, BRAF, APC, etc.), as well as expression signatures (CMS 1-4). It is also suggested that the tumor microenvironment is a key player in tumor progression and metastasis in CRC. According to the latest data, the immune microenvironment can also be predictive of the response to immune checkpoint inhibitors. In this review, we highlight how the immune environment influences CRC prognosis and sensitivity to systemic therapy.

Efficacy of immune checkpoint inhibitors for metastatic colorectal cancer with microsatellite instability in second or latter line using synthetic control arms: A non-randomised evaluation

PURPOSE

Immune checkpoint inhibitors (ICIs) appeared active in single-arm trials for patients with chemoresistant metastatic colorectal cancer (mCRC) harboring microsatellite instability (MSI). Given the paucity of randomised controlled trials (RCTs) in this setting, we evaluated the effect size of ICIs using intra-patients comparison and ARCAD database as historical controls.

PATIENTS AND METHODS

Individual-patient data from NIPICOL and CheckMate 142 phase II trials that evaluated a combination of ICIs for MSI mCRC patients (N = 176) and from five non-ICI mCRC historical RCTs in second-line or latter (N = 4026) were analyzed. Firstly, promising of ICIs was identified using intra-patient comparison based on growth modulation index (GMI) defined the ratio of progression-free survivals (PFS) on ICIs and previous line of therapy. Survival outcomes of ICIs-treated patients were then compared with those matched non-ICIs treated from ARCAD database historical RCTs.

RESULTS

Among ICIs-treated patients, median PFS on ICIs was 32.66 (range 0.10-74.25) versus 4.07 months (range 0.7-49.87) on prior therapy, resulting on median GMI of 4.97 (range 0.07-59.51; hazard-ratio (HR)= 0.16 (95 %CI=0.11-0.22, P < 0.001)). Compared to matched non-ICI patients, in third-line, median overall survival (OS) was not reached with ICIs versus 3.52 months with placebo (HR=0.20, 95 %CI=0.10-0.41, P < 0.001), and 6.51 months with active drugs (HR=0.30, 95 %CI=0.15-0.60, P = 0.001). In second-line, median OS was not reached with ICIs versus 11.7 months with chemotherapy+placebo (HR=0.12, 95 %CI=0.07-0.22, P < 0.001), and 16.3 months with chemotherapy+targeted therapy (HR=0.10, 95 %CI=0.05-0.19, P < 0.001).

CONCLUSION

ICIs demonstrates high effect size for MSI mCRC patients in second-line and later. This work might be useful as an example of methodology to avoid RCTs when benefit from experimental therapy is likely to be high.

Preoperative chemotherapy in upfront resectable colorectal liver metastases: New elements for an old dilemma?

The use of preoperative or "neoadjuvant" chemotherapy (NAC) has long been controversial for resectable colorectal liver metastases (CRLM). The European Society of Medical Oncology (ESMO) 2023 guidelines on metastatic colorectal cancer (CRC) indicate a combination of surgical/technical and oncologic/prognostic criteria as the two determinants for allocating patients to NAC or upfront hepatectomy. However, surgical and technical criteria have evolved, and oncologic prognostic criteria date from the pre-modern chemotherapy era and lack prospective validation. The traditional literature is interpreted as not supporting the use of NAC because several studies fail to demonstrate a benefit in overall survival (OS) compared to upfront surgery; however, OS may not be the most appropriate endpoint to consider. Moreover, the commonly quoted studies against NAC contain many limitations that may explain why NAC failed to demonstrate its value. The query of the recent literature focused primarily on other aspects than OS, such as surgical technique, the impact of side effects of chemotherapy, the histological growth pattern of metastases, or the detection of circulating tumor DNA, shows data that support a more widespread use of NAC. These should prompt a critical reappraisal of the use of NAC, leading to a more precise selection of patients who could benefit from it.

Clinical and biomarker results from a phase II trial of combined cabozantinib and durvalumab in patients with chemotherapy-refractory colorectal cancer (CRC): CAMILLA CRC cohort

CAMILLA is a basket trial (NCT03539822) evaluating cabozantinib plus the ICI durvalumab in chemorefractory gastrointestinal cancer. Herein, are the phase II colorectal cohort results. 29 patients were evaluable. 100% had confirmed pMMR/MSS tumors. Primary endpoint was met with ORR of 27.6% (95% CI 12.7-47.2%). Secondary endpoints of 4-month PFS rate was 44.83% (95% CI 26.5-64.3%); and median OS was 9.1 months (95% CI 5.8-20.2). Grade≥3 TRAE occurred in 39%. In post-hoc analysis of patients with RAS wild type tumors, ORR was 50% and median PFS and OS were 6.3 and 21.5 months respectively. Exploratory spatial transcriptomic profiling of pretreatment tumors showed upregulation of VEGF and MET signaling, increased extracellular matrix activity and preexisting anti-tumor immune responses coexisting with immune suppressive features like T cell migration barriers in responders versus non-responders. Cabozantinib plus durvalumab demonstrated anti-tumor activity, manageable toxicity, and have led to the activation of the phase III STELLAR-303 trial.

Lynch Syndrome: From Multidisciplinary Management to Precision Prevention

BACKGROUND AND AIMS

Lynch syndrome (LS) is currently one of the most prevalent hereditary cancer conditions, accounting for 3% of all colorectal cancers and for up to 15% of those with DNA mismatch repair (MMR) deficiency, and it was one of the first historically identified. The understanding of the molecular carcinogenesis of LS tumors has progressed significantly in recent years. We aim to review the most recent advances in LS research and explore genotype-based approaches in surveillance, personalized cancer prevention, and treatment strategies.

METHODS

PubMed was searched to identify relevant studies, conducted up to December 2023, investigating molecular carcinogenesis in LS, surveillance strategies, cancer prevention, and treatment in LS tumors.

RESULTS

Multigene panel sequencing is becoming the benchmark in the diagnosis of LS, allowing for the detection of a pathogenic constitutional variant in one of the MMR genes. Emerging data from randomized controlled trials suggest possible preventive roles of resistant starch and/or aspirin in LS. Vaccination with immunogenic frameshift peptides appears to be a promising approach for both the treatment and prevention of LS-associated cancers, as evidenced by pre-clinical and preliminary phase 1/2a studies.

CONCLUSIONS

Although robust diagnostic algorithms, including prompt testing of tumor tissue for MMR defects and referral for genetic counselling, currently exist for suspected LS in CRC patients, the indications for LS screening in cancer-free individuals still need to be refined and standardized. Investigation into additional genetic and non-genetic factors that may explain residual rates of interval cancers, even in properly screened populations, would allow for more tailored preventive strategies.

Combined Immunotherapy Improves Outcome for Replication-Repair-Deficient (RRD) High-Grade Glioma Failing Anti-PD-1 Monotherapy: A Report from the International RRD Consortium

Immune checkpoint inhibition (ICI) is effective for replication-repair-deficient, high-grade gliomas (RRD-HGG). The clinical/biological impact of immune-directed approaches after failing ICI monotherapy is unknown. We performed an international study on 75 patients treated with anti-PD-1; 20 are progression free (median follow-up, 3.7 years). After second progression/recurrence (n = 55), continuing ICI-based salvage prolonged survival to 11.6 months (n = 38; P < 0.001), particularly for those with extreme mutation burden (P = 0.03). Delayed, sustained responses were observed, associated with changes in mutational spectra and the immune microenvironment. Response to reirradiation was explained by an absence of deleterious postradiation indel signatures (ID8). CTLA4 expression increased over time, and subsequent CTLA4 inhibition resulted in response/stable disease in 75%. RAS-MAPK-pathway inhibition led to the reinvigoration of peripheral immune and radiologic responses. Local (flare) and systemic immune adverse events were frequent (biallelic mismatch-repair deficiency > Lynch syndrome). We provide a mechanistic rationale for the sustained benefit in RRD-HGG from immune-directed/synergistic salvage therapies. Future approaches need to be tailored to patient and tumor biology.

SIGNIFICANCE

Hypermutant RRD-HGG are susceptible to checkpoint inhibitors beyond initial progression, leading to improved survival when reirradiation and synergistic immune/targeted agents are added. This is driven by their unique biological and immune properties, which evolve over time. Future research should focus on combinatorial regimens that increase patient survival while limiting immune toxicity. This article is featured in Selected Articles from This Issue, p. 201.

Construction and validation of a colon cancer prognostic model based on tumor mutation burden-related genes

Currently, immunotherapy has entered the clinical diagnosis and treatment guidelines for colon cancer, but existing immunotherapy markers cannot predict the effectiveness of immunotherapy well. This study utilized the TCGA-COAD queue to perform differential gene analysis on high and low-mutation burden samples, and screen differentially expressed genes (DEGs). To explore new molecular markers or predictive models of immunotherapy by using DEGs for NMF classification and prognostic model construction. Through systematic bioinformatics analysis, the TCGA-COAD cohort was successfully divided into high mutation burden subtypes and low mutation burden subtypes by NMF typing using DEGs. The proportion of MSI-H between high mutation burden subtypes was significantly higher than that of low mutation burden subtypes, but there was no significant difference in immunotherapy efficacy between the two subtypes. Drug sensitivity analysis showed significant differences in drug sensitivity between the two subtypes. Subsequently, we constructed a prognostic model using DEGs, which can effectively predict patient survival and immunotherapy outcomes. The prognosis and immunotherapy outcomes of the low-risk group were significantly better than those of the high-risk group. The external dataset validation of the constructed prognostic model using the GSE39582 dataset from the GEO database yielded consistent results. At the same time, we also analyzed the TMB and MSI situation between the high and low-risk groups, and the results showed that there was no significant difference in TMB between the high and low-risk groups, but the proportion of MSI-H in the high-risk group was significantly higher than that in the low-risk group. Finally, we conclude that TMB is not a suitable molecular marker for predicting the efficacy of immunotherapy in colon cancer. The newly constructed prognostic model can effectively differentiate the prognosis of colon cancer patients and predict their immunotherapy efficacy.

Immunotherapy in mismatch repair-deficient metastatic colorectal cancer - Outcome and novel predictive markers

BACKGROUND

This study aims to assess predictive markers for response to immunotherapy in dMMR/MSI-H metastatic colorectal cancer (mCRC) patients.

MATERIALS AND METHODS

A study using two prospective cohorts from MD Anderson Cancer Center and Sheba Medical Center of consecutive patients with dMMR/MSI-H mCRC that were treated with immunotherapy between 2014-2022. Primary outcome was progression-free survival (PFS) and secondary outcome was overall response rate (ORR). Evaluated predictors included ECOG-PS score, RAS/BRAF status, single-agent versus doublet immunotherapy, metastatic sites, disease burden, and CEA levels prior to treatment initiation. Kaplan-Meier analysis and Cox proportional hazard regression model were used to analyze the effect of exposure variables on PFS.

RESULTS

The study included 153 patients. Median follow-up time was 26 months (IQR 11-48). Median PFS was 51.6 months (95%CI 38.1-NR) and ORR was 58.1%. In a univariate analysis, male sex was associated with worse PFS with a HR of 1.67 (95% CI 1.00-2.79); Right-sided tumors were associated with improved PFS with a HR of 0.56 (95% CI 0.32-0.97); Liver or lung metastasis were associated with worse PFS with HRs of 2.35 (95%CI 1.43-3.88) and 2.30 (95%CI 1.31-4.04), respectively; ECOG-PS score ≥ 2, CEA levels ˃5 μg/L prior to treatment initiation and ≥ 3 metastatic sites were associated with worse PFS with HRs of 2.09 (95%CI 0.98-4.47), 2.23 (95%CI 1.30-3.81) and 3.11 (95%CI 1.61-6.03), respectively. Liver or lung metastasis remained significant in a multivariable model.

CONCLUSIONS

Extent of disease (worse PFS with high CEA, poor ECOG-PS and ≥3 metastatic sites) and disease location (worse PFS with liver or lung metastasis and left sided tumor) were associated with immunotherapy outcome in dMMR/MSI-H mCRC.

Case report: Efficacy of immunotherapy as conversion therapy in dMMR/MSI-H colorectal cancer: a case series and review of the literature

Immunotherapy has demonstrated a role in the therapeutic landscape of a small subset of patients with colorectal carcinoma (CRC) that harbor a microsatellite instability (MSI-H) status due to a deficient DNA mismatch repair (dMMR) system. The remarkable responses to immune checkpoint inhibitors (ICIs) are now being tested in the neoadjuvant setting in localized CRC, where the dMMR/MSI-H status can be found in up to 15% of patients, with remarkable results obtained in NICHE2 and 3 trials, among others. This case series aims to report our experience at a tertiary center and provide a comprehensive analysis of the possible questions and challenges to overcome if ICIs were established as standard of care in a neoadjuvant setting, as well as the potential role they may have as conversion therapy not only in locoregional advanced CRC but also in oligometastatic disease.

Deficient mismatch repair/microsatellite unstable colorectal cancer: therapeutic advances and questions

The microsatellite instability (MSI) phenotype is related to a deficiency of the DNA mismatch repair (dMMR) system and is observed in 5% of metastatic colorectal cancers (mCRCs). MSI/dMMR phenotype testing should be routine for all CRCs regardless of stage. Two complementary techniques with a high concordance (90-97%) allow us to determine the MSI/dMMR status of a tumor: immunohistochemistry and polymerase chain reaction. Since 2020 and the results of the phase III KEYNOTE 177 trial, pembrolizumab [anti-programmed cell death protein 1 (PD1)] is the new standard of care in first-line MSI/dMMR mCRC. To date, no combination of chemtotherapy ± targeted therapy with immune checkpoint inhibitors (ICIs) has been validated in the management of MSI/dMMR mCRC, and it is not known whether this combination would be beneficial. It is also unclear whether dual therapy with two ICIs is more effective than monotherapy. Several phase III trials are ongoing to answer these questions. Despite a high response rate and long-term benefit of a first line by anti-PD1, 30-50% of patients with MSI/dMMR mCRC experience an early or secondary progression. There are currently no validated predictive biomarkers of anti-PD1 ± anti-cytotoxic T lymphocyte antigen-4 resistance in patients with MSI/dMMR mCRC. In case of early progression on ICIs, the first two questions to consider are the possibility of pseudoprogression and the correct diagnosis of MSI/dMMR status. To date, there are no data on the use of adjuvant ICIs for MSI/dMMR resected colon cancers. By contrast, data are accumulating regarding the efficacy of neoadjuvant ICIs, with at least two-thirds of patients in the different trials in pathological complete response, making it possible to envisage 'Watch and wait' strategies in future.

Beyond PD(L)-1 Blockade in Microsatellite-Instable Cancers: Current Landscape of Immune Co-Inhibitory Receptor Targeting

High microsatellite instability (MSI-H) derives from genomic hypermutability due to deficient mismatch repair function. Colorectal (CRC) and endometrial cancers (EC) are the tumor types that more often present MSI-H. Anti-PD(L)-1 antibodies have been demonstrated to be agnostically effective in patients with MSI-H cancer, but 50-60% of them do not respond to single-agent treatment, highlighting the necessity of expanding their treatment opportunities. Ipilimumab (anti-CTLA4) is the only immune checkpoint inhibitor (ICI) non-targeting PD(L)-1 that has been approved so far by the FDA for MSI-H cancer, namely, CRC in combination with nivolumab. Anti-TIM3 antibody LY3321367 showed interesting clinical activity in combination with anti-PDL-1 antibody in patients with MSI-H cancer not previously treated with anti-PD(L)-1. In contrast, no clinical evidence is available for anti-LAG3, anti-TIGIT, anti-BTLA, anti-ICOS and anti-IDO1 antibodies in MSI-H cancers, but clinical trials are ongoing. Other immunotherapeutic strategies under study for MSI-H cancers include vaccines, systemic immunomodulators, STING agonists, PKM2 activators, T-cell immunotherapy, LAIR-1 immunosuppression reversal, IL5 superagonists, oncolytic viruses and IL12 partial agonists. In conclusion, several combination therapies of ICIs and novel strategies are emerging and may revolutionize the treatment paradigm of MSI-H patients in the future. A huge effort will be necessary to find reliable immune biomarkers to personalize therapeutical decisions.

Review - The impact of pharmacogenetics on the outcome of immune checkpoint inhibitors

The development of immune checkpoint inhibitors (ICIs) has a tremendous effect on the treatment options for multiple types of cancer. Nonetheless, there is a large interpatient variability in response, survival, and the development of immune-related adverse events (irAEs). Pharmacogenetics is the general term for germline genetic variations, which may cause the observed interindividual differences in response or toxicity to treatment. These genetic variations can either be single-nucleotide polymorphisms (SNPs) or structural variants, such as gene deletions, amplifications or rearrangements. For ICIs, pharmacogenetic variation in the human leukocyte antigen molecules has also been studied with regard to treatment outcome. This review presents a summary of the literature regarding the pharmacogenetics of ICI treatment, discusses the most important known genetic variations and offers recommendations on the application of pharmacogenetics for ICI treatment.

Opposing roles by KRAS and BRAF mutation on immune cell infiltration in colorectal cancer - possible implications for immunotherapy

BACKGROUND

The immune response has important clinical value in colorectal cancer (CRC) in both prognosis and response to immunotherapy. This study aims to explore tumour immune cell infiltration in relation to clinically well-established molecular markers of CRC.

METHODS

Multiplex immunohistochemistry and multispectral imaging was used to evaluate tumour infiltration of cytotoxic T cells (CD8+), Th1 cells (T-bet+), T regulatory cells (FoxP3+), B cells (CD20+), and macrophages (CD68+) in a cohort of 257 CRC patients.

RESULTS

We found the expected association between higher immune-cell infiltration and microsatellite instability. Also, whereas BRAF-mutated tumours displayed increased immune-cell infiltration compared to BRAF wild-type tumours, the opposite was seen for KRAS-mutated tumours, differences that were most prominent for cytotoxic T cells and Th1 cells. The opposing relationships of BRAF and KRAS mutations with tumour infiltration of cytotoxic T cells was validated in an independent cohort of 608 CRC patients. A positive prognostic importance of cytotoxic T cells was found in wild-type as well as KRAS and BRAF-mutated CRCs in both cohorts.

CONCLUSION

A combined evaluation of MSI status, KRAS and BRAF mutational status, and immune infiltration (cytotoxic T cells) may provide important insights to prognosis and response to immunotherapy in CRC.

The current status and prospect of immunotherapy in colorectal cancer

Metastatic colorectal cancer (mCRC) is a heterogeneous disease. We reviewed the current clinical trials on immunotherapy in metastatic colorectal cancer with high microsatellite instability and microsatellite stability. Owing to the advances in immunotherapy, its use has gradually expanded from second- and third-line therapies to first-line, early neoadjuvant, and adjuvant therapies. Based on current research results, immunotherapy has shown very good results in dMMR/MSI-H patients, whether it is neoadjuvant therapy for operable patients or first-line or multi-line therapy for advanced patients. KEYNOTE 016 study also showed that patients with MSS were basically ineffective in single immunotherapy. Moreover, immunotherapy for colorectal cancer may also require identification of new biomarkers.

PD-1 and PD-L1: architects of immune symphony and immunotherapy breakthroughs in cancer treatment

PD-1 (Programmed Cell Death Protein-1) and PD-L1 (Programmed Cell Death Ligand-1) play a crucial role in regulating the immune system and preventing autoimmunity. Cancer cells can manipulate this system, allowing them to escape immune detection and promote tumor growth. Therapies targeting the PD-1/PD-L1 pathway have transformed cancer treatment and have demonstrated significant effectiveness against various cancer types. This study delves into the structure and signaling dynamics of PD-1 and its ligands PD-L1/PD-L2, the diverse PD-1/PD-L1 inhibitors and their efficacy, and the resistance observed in some patients. Furthermore, this study explored the challenges associated with the PD-1/PD-L1 inhibitor treatment approach. Recent advancements in the combination of immunotherapy with chemotherapy, radiation, and surgical procedures to enhance patient outcomes have also been highlighted. Overall, this study offers an in-depth overview of the significance of PD-1/PD-L1 in cancer immunotherapy and its future implications in oncology.

KEYSTEP-008: phase II trial of pembrolizumab-based combination in MSI-H/dMMR metastatic colorectal cancer

Robust clinical activity has been observed with the immune checkpoint inhibitor pembrolizumab in patients with microsatellite instability-high/mismatch repair-deficient (MSI-H/dMMR) metastatic colorectal cancer (mCRC). However, given the response rate of 45% and a median progression-free survival of 16.5 months with first-line pembrolizumab demonstrated in KEYNOTE-177, there is room for improvement. Targeting a second immune receptor, such as CTLA-4, LAG-3, TIGIT, or ILT-4 may improve efficacy of PD-1 inhibition. Here we describe the design and rationale for the open-label, randomized, phase II KEYSTEP-008 trial, which will evaluate the efficacy and safety of pembrolizumab-based combination therapy compared with pembrolizumab monotherapy in chemotherapy-refractory (cohort A) or previously untreated (cohort B) MSI-H/dMMR mCRC. Clinical Trial Registration: NCT04895722 (ClinicalTrials.gov).

[Novel Treatment Concepts in Patients with Colorectal Carcinomas and High Microsatellite Instability]

Approximately 15% of patients with colorectal cancer show high microsatellite instability (MSI-high) in their tumour tissue. For one third of these patients, there is a hereditary cause for this finding - that leads to the diagnosis of Lynch Syndrome. In combination with clinical findings such as the Amsterdam or the revised Bethesda criteria, MSI-high status has been used as a tool in identifying patients at risk. Today, MSI-status has gained much more importance, due to its impact on treatment decisions. Patients with UICC II cancers should not receive adjuvant treatment. For patients with distant metastases and MSI-high status, immune checkpoint inhibitors can be given as first line therapy - with tremendous success. Novel data show a deep response for immune checkpoint antibodies in patients with locally advanced colon as well as rectal cancer in a neoadjuvant setting. Especially for patients with MSI-high rectal cancer, there might be a novel therapeutic regimen utilising immune checkpoint inhibitors without neoadjuvant radio-chemotherapy and even without surgery. This could lead to a relevant reduction in morbidity in this patient cohort. In conclusion, universal MSI-testing is essential for identifying patients at risk for Lynch syndrome and for optimal decision making in treatment planning.

Potentiation of natural killer cells to overcome cancer resistance to NK cell-based therapy and to enhance antibody-based immunotherapy

Natural killer (NK) cells are cellular components of the innate immune system that can recognize and suppress the proliferation of cancer cells. NK cells can eliminate cancer cells through direct lysis, by secreting perforin and granzymes, or through antibody-dependent cell-mediated cytotoxicity (ADCC). ADCC involves the binding of the Fc gamma receptor IIIa (CD16), present on NK cells, to the constant region of an antibody already bound to cancer cells. Cancer cells use several mechanisms to evade antitumor activity of NK cells, including the accumulation of inhibitory cytokines, recruitment and expansion of immune suppressor cells such as myeloid-derived suppressor cells (MDSCs) and regulatory T cells (Tregs), modulation of ligands for NK cells receptors. Several strategies have been developed to enhance the antitumor activity of NK cells with the goal of overcoming cancer cells resistance to NK cells. The three main strategies to engineer and boost NK cells cytotoxicity include boosting NK cells with modulatory cytokines, adoptive NK cell therapy, and the employment of engineered NK cells to enhance antibody-based immunotherapy. Although the first two strategies improved the efficacy of NK cell-based therapy, there are still some limitations, including immune-related adverse events, induction of immune-suppressive cells and further cancer resistance to NK cell killing. One strategy to overcome these issues is the combination of monoclonal antibodies (mAbs) that mediate ADCC and engineered NK cells with potentiated anti-cancer activity. The advantage of using mAbs with ADCC activity is that they can activate NK cells, but also favor the accumulation of immune effector cells to the tumor microenvironment (TME). Several clinical trials reported that combining engineered NK cells with mAbs with ADCC activity can result in a superior clinical response compared to mAbs alone. Next generation of clinical trials, employing engineered NK cells with mAbs with higher affinity for CD16 expressed on NK cells, will provide more effective and higher-quality treatments to cancer patients.

Current status and prospect of immunotherapy for colorectal cancer

PURPOSE

Colorectal cancer is the most common gastrointestinal tumor in China. While significant progress has been achieved in traditional chemotherapy, radiotherapy, and targeted therapy, the prognosis of advanced colorectal cancer is poor, and the five-year survival rate is unsatisfactory. There is an urgent need to explore new treatment modalities. In this review, we examined the latest progress of colorectal cancer immunotherapy and discussed its future prospects.

METHODS

We conducted a literature review to sort out the current status of immunotherapy for different types of colorectal cancer and discussed potential combination therapy options. Results Subsequent line therapy, first-line therapy and neoadjuvant therapy for MSI-H/dMMR colorectal cancer are discussed. In addition, combination therapy options for patients with MSS/pMMR colorectal cancer are presented. Finally, current valuable biomarkers for immunotherapy are highlighted.

RESULTS

Subsequent line therapy, first-line therapy and neoadjuvant therapy for MSI-H/dMMR colorectal cancer are discussed. In addition, combination therapy options for patients with MSS/pMMR colorectal cancer are presented. Finally, current valuable biomarkers for immunotherapy are highlighted.

CONCLUSION

This review discussed the current status of immunotherapy for different types of colorectal cancer and biomarkers for immunotherapy.

Lasting response by vertical inhibition with cetuximab and trametinib in KRAS-mutated colorectal cancer patient-derived xenografts

Although approximately half of all metastatic colorectal cancers (mCRCs) harbour mutations in KRAS or NRAS, hardly any progress has been made regarding targeted treatment for this group over the last few years. Here, we investigated the efficacy of vertical inhibition of the RAS-pathway by targeting epidermal growth factor receptor (EGFR) and mitogen-activated protein kinase kinase (MEK) in patient-derived xenograft (PDX) tumours with primary KRAS mutation. In total, 19 different PDX models comprising 127 tumours were tested. Responses were evaluated according to baseline tumour volume changes and graded as partial response (PR; ≤ - 30%), stable disease (SD; between -30% and +20%) or progressive disease (PD; ≥ + 20%). Vertical inhibition with trametinib and cetuximab induced SD or PR in 74% of analysed models, compared to 24% by monotherapy with trametinib. In cases of PR by vertical inhibition (47%), responses were lasting (as long as day 137), with a low incidence of secondary resistance (SR). Molecular analyses revealed that primary and SR was driven by transcriptional reprogramming activating the RAS pathway in a substantial fraction of tumours. Together, these preclinical data strongly support the translation of this combination therapy into clinical trials for CRC patients.

Facts and Hopes in Colorectal Cancer Immunotherapy

Although a minority of colorectal cancers exhibit mismatch repair deficiency and associated sensitivity to immune checkpoint inhibitors (ICI), the vast majority of colorectal cancers arise in a tolerogenic microenvironment with mismatch repair proficiency, low tumor-intrinsic immunogenicity, and negligible immunotherapy responsiveness. Treatment strategies to augment tumor immunity with combination ICIs and chemotherapy have broadly failed in mismatch repair-proficient tumors. Similarly, although several small single-arm studies have shown that checkpoint blockade plus radiation or select tyrosine kinase inhibition may show improved outcomes compared with historical controls, this finding has not been clearly validated in randomized trials. An evolving next generation of intelligently engineered checkpoint inhibitors, bispecific T-cell engagers, and emerging CAR-T cell therapies may improve immunorecognition of colorectal tumors. Across these modalities, ongoing translational efforts to better define patient populations and biomarkers associated with immune response, as well as combine biologically sound and mutually amplifying therapies, show promise for a new era of immunotherapy in colorectal cancer.

Interventional pharmacoeconomics for immune checkpoint inhibitors through alternative dosing strategies

Immune checkpoint inhibitors (ICIs) are approved for the treatment of a variety of cancer types. The doses of these drugs, though approved by the Food and Drug Administration (FDA), have never been optimised, likely leading to significantly higher doses than required for optimal efficacy. Dose optimisation would hypothetically decrease the risk, severity, and duration of immune-related adverse events, as well as provide an opportunity to reduce costs through interventional pharmacoeconomic strategies such as off-label dose reductions or less frequent dosing. We summarise existing evidence for ICI dose optimisation to advocate for the role of interventional pharmacoeconomics.

Progresses in biomarkers for cancer immunotherapy

Currently, checkpoint inhibitor-based immunotherapy has emerged as prevailing treatment modality for diverse cancers. However, immunotherapy as a first-line therapy has not consistently yielded durable responses. Moreover, the risk of immune-related adverse events increases with combination regimens. Thus, the development of predictive biomarkers is needed to optimize individuals benefit, minimize risk of toxicities, and guide combination approaches. The greatest focus has been on tumor programmed cell death-ligand 1 (PD-L1), microsatellite instability (MSI), and tumor mutational burden (TMB). However, there remains a subject of debate due to thresholds variability and significant heterogeneity. Major unmet challenges in immunotherapy are the discovery and validation of predictive biomarkers. Here, we show the status of tumor PD-L1, MSI, TMB, and emerging data on novel biomarker strategies with oncogenic signaling and epigenetic regulation. Considering the exploration of peripheral and intestinal immunity has served as noninvasive alternative in predicting immunotherapy, this review also summarizes current data in systemic immunity, encompassing solute PD-L1 and TMB, circulating tumor DNA and infiltrating lymphocytes, routine emerging inflammatory markers and cytokines, as well as gut microbiota. This review provides up-to-date information on the evolving field of currently available biomarkers in predicting immunotherapy. Future exploration of novel biomarkers is warranted.

Mirroring UC care pathways in refractory immune checkpoint inhibitor (ICI)-mediated colitis: distinct features and common pathways

Immune checkpoint inhibitors (ICI) have transformed the management of cancer, producing durable responses in a subset of treated patients across multiple malignancies. Immune-mediated diarrhea and colitis (imDC) occurs in up to 20% of ICI-treated patients. The risk of ICI imDC is dependent upon the agent and is commoner with anti-CTLA-4 compared to anti-PD-1 ICIs. Generally, imDC is treated with steroids and agents targeting TNFα or α4β7 integrin. However, the management of steroids and/or biologic refractory imDC is unclear. We present a case of imDC in a 68-year-old female who failed to respond clinically, biochemically and immunohistochemically to corticosteroids, infliximab and vedolizumab. A trial of tofacitinib, a pan-JAK inhibitor, led to rapid clinical, biochemical and immunohistochemical control of imDC. ICIs result in a striking accumulation of cytotoxic and proliferative CD8 + T cells within tumor. However, the cellular and molecular mechanisms underlying imDC remain unclear. Herein, we observed significant T cell enrichment; and the successful treatment with tofacitinib highlights the potential of multiple convergent inflammatory pathways in imDC and inflammatory colitis.

BRAF V600E/RAS Mutations and Lynch Syndrome in Patients With MSI-H/dMMR Metastatic Colorectal Cancer Treated With Immune Checkpoint Inhibitors

BACKGROUND

We pooled data from 2 cohorts of immune checkpoint inhibitors-treated microsatellite instability-high/mismatch repair-deficient (MSI/dMMR) metastatic colorectal cancer patients to evaluate the prognostic value of RAS/BRAFV600E mutations and Lynch syndrome (LS).

PATIENTS AND METHODS

Patients were defined as LS-linked if germline mutation was detected and as sporadic if loss of MLH1/PMS2 expression with BRAFV600E mutation and/or MLH1 promoter hypermethylation, or biallelic somatic MMR genes mutations were found. Progression-free survival (PFS) and overall survival (OS) were adjusted on prognostic modifiers selected on unadjusted analysis (P < .2) if limited number of events.

RESULTS

Of 466 included patients, 305 (65.4%) and 161 (34.5%) received, respectively, anti-PD1 alone and anti-PD1+anti-CTLA4 in the total population, 111 (24.0%) were treated in first-line; 129 (28.8%) were BRAFV600E-mutated and 153 (32.8%) RAS-mutated. Median follow-up was 20.9 months. In adjusted analysis of the whole population (PFS/OS events = 186/133), no associations with PFS and OS were observed for BRAFV600E-mutated (PFS HR= 1.20, P = .372; OS HR = 1.06, P = .811) and RAS-mutated patients (PFS HR = 0.93, P = .712, OS HR = 0.75, P = .202). In adjusted analysis in the Lynch/sporadic status-assigned population (n = 242; PFS/OS events = 80/54), LS-liked patients had an improved PFS compared to sporadic cases (HR = 0.49, P = .036). The adjusted HR for OS was 0.56 with no significance (P = .143). No adjustment on BRAFV600E mutation was done due to collinearity.

CONCLUSION

In this cohort, RAS/BRAFV600E mutations were not associated with survival while LS conferred an improved PFS.

Early-Onset Colon Cancer: A Narrative Review of Its Pathogenesis, Clinical Presentation, Treatment, and Prognosis

Colon cancer remains a leading cause of cancer-related deaths, and there has been a rise in the incidence of early-onset colon cancer or colon cancer diagnosed before the age of 50 years old. Early-onset colon cancer has several differences in clinical presentation, as well as histopathology, genetic alteration, and molecular profiling. Early-onset colon cancer can be differentiated into familial type that includes hereditary familial syndrome and sporadic type. Demographic variance also exists in both developing and developed countries. Due to the rising incidence of colon cancer diagnosed in younger age, it is imperative to examine the available evidence regarding the mortality rate of early-onset colon cancer. Colon cancer is affected by numerous modifiable and non-modifiable risk factors. Increasing obesity and lifestyle disorders in the younger population, such as smoking, may influence this increasing trend. There are existing guidelines for colon cancer screening in both average-risk and high-risk individuals. This narrative review aims to highlight the pathogenesis of early-onset CRC; its clinical presentation, treatment, prognosis; and how it differs from late-onset CRC.

DNA mismatch repair in cancer immunotherapy

Tumors defective in DNA mismatch repair (dMMR) exhibit microsatellite instability (MSI). Currently, patients with dMMR tumors are benefitted from anti-PD-1/PDL1-based immune checkpoint inhibitor (ICI) therapy. Over the past several years, great progress has been made in understanding the mechanisms by which dMMR tumors respond to ICI, including the identification of mutator phenotype-generated neoantigens, cytosolic DNA-mediated activation of the cGAS-STING pathway, type-I interferon signaling and high tumor-infiltration of lymphocytes in dMMR tumors. Although ICI therapy shows great clinical benefits, ∼50% of dMMR tumors are eventually not responsive. Here we review the discovery, development and molecular basis of dMMR-mediated immunotherapy, as well as tumor resistant problems and potential therapeutic interventions to overcome the resistance.

SEOM-GEMCAD-TTD clinical guidelines for the systemic treatment of metastatic colorectal cancer (2022)

Colorectal cancer (CRC) is the second leading cause of cancer deaths in Spain. Metastatic disease is present in 15-30% of patients at diagnosis and up to 20-50% of those with initially localized disease eventually develop metastases. Recent scientific knowledge acknowledges that this is a clinically and biologically heterogeneous disease. As treatment options increase, prognosis for individuals with metastatic disease has steadily improved over recent decades. Disease management should be discussed among experienced, multidisciplinary teams to select the most appropriate systemic treatment (chemotherapy and targeted agents) and to integrate surgical or ablative procedures, when indicated. Clinical presentation, tumor sidedness, molecular profile, disease extension, comorbidities, and patient preferences are key factors when designing a customized treatment plan. These guidelines seek to provide succinct recommendations for managing metastatic CRC.

Immune checkpoint therapy for solid tumours: clinical dilemmas and future trends

Immune-checkpoint inhibitors (ICBs), in addition to targeting CTLA-4, PD-1, and PD-L1, novel targeting LAG-3 drugs have also been approved in clinical application. With the widespread use of the drug, we must deeply analyze the dilemma of the agents and seek a breakthrough in the treatment prospect. Over the past decades, these agents have demonstrated dramatic efficacy, especially in patients with melanoma and non-small cell lung cancer (NSCLC). Nonetheless, in the field of a broad concept of solid tumours, non-specific indications, inseparable immune response and side effects, unconfirmed progressive disease, and complex regulatory networks of immune resistance are four barriers that limit its widespread application. Fortunately, the successful clinical trials of novel ICB agents and combination therapies, the advent of the era of oncolytic virus gene editing, and the breakthrough of the technical barriers of mRNA vaccines and nano-delivery systems have made remarkable breakthroughs currently. In this review, we enumerate the mechanisms of each immune checkpoint targets, associations between ICB with tumour mutation burden, key immune regulatory or resistance signalling pathways, the specific clinical evidence of the efficacy of classical targets and new targets among different tumour types and put forward dialectical thoughts on drug safety. Finally, we discuss the importance of accurate triage of ICB based on recent advances in predictive biomarkers and diagnostic testing techniques.

Immunotherapy for Colorectal Cancer with High Microsatellite Instability: The Ongoing Search for Biomarkers

Microsatellite instability (MSI) is a biological condition associated with inflamed tumors, high tumor mutational burden (TMB), and responses to immune checkpoint inhibitors. In colorectal cancer (CRC), MSI tumors are found in 5% of patients in the metastatic setting and 15% in early-stage disease. Following the impressive clinical activity of immune checkpoint inhibitors in the metastatic setting, associated with deep and long-lasting responses, the development of immune checkpoint inhibitors has expanded to early-stage disease. Several phase II trials have demonstrated a high rate of pathological complete responses, with some patients even spared from surgery. However, in both settings, not all patients respond and some responses are short, emphasizing the importance of the ongoing search for accurate biomarkers. While various biomarkers of response have been evaluated in the context of MSI CRC, including B2M and JAK1/2 mutations, TMB, WNT pathway mutations, and Lynch syndrome, with mixed results, liver metastases have been associated with a lack of activity in such strategies. To improve patient selection and treatment outcomes, further research is required to identify additional biomarkers and refine existing ones. This will allow for the development of personalized treatment approaches and the integration of novel therapeutic strategies for MSI CRC patients with liver metastases.

Functional analysis of CTLA4 promoter variant and its possible implication in colorectal cancer immunotherapy

Background

Colorectal cancer (CRC) is a prevalent cancer, ranking as the third most common. Recent advances in our understanding of the molecular causes of this disease have highlighted the crucial role of tumor immune evasion in its initiation and progression. CTLA4, a receptor that acts as a negative regulator of T cell responses, plays a pivotal role in this process, and genetic variations in CTLA4 have been linked to CRC susceptibility, prognosis, and response to therapy.

Methods

We conducted a case-control study involving 98 CRC patients and 424 controls. We genotyped the CTLA4 c.-319C > T variant (rs5742909) and performed an association analysis by comparing allele frequencies between the patients and controls. To assess the potential functional impact of this variant, we first performed an In Silico analysis of transcription factor binding sites using Genomatix. Finally, to validate our findings, we conducted a luciferase reporter gene assay using different cell lines and an electrophoretic mobility shift assay (EMSA).

Results

The case-control association analysis revealed a significant association between CTLA4 c.-319C > T and CRC susceptibility (p = 0.023; OR 1.89; 95% CI = 1.11-3.23). Genomatix analysis identified LEF1 and TCF7 transcription factors as specific binders to CTLA4 c.-319C. The reporter gene assay demonstrated notable differences in luciferase activity between the c.-319 C and T alleles in COS-7, HCT116, and Jurkat cell lines. EMSA analysis showed differences in TCF7 interaction with the CTLA4 C and T alleles.

Conclusion

CTLA4 c.-319C > T is associated with CRC susceptibility. Based on our functional validation results, we proposed that CTLA4 c.-319C > T alters gene expression at the transcriptional level, triggering a stronger negative regulation of T-cells and immune tumoral evasion.

Lynch Syndrome Biopathology and Treatment: The Potential Role of microRNAs in Clinical Practice

Lynch syndrome (LS), also known as Hereditary Non-Polyposis Colorectal Cancer (HNPCC), is an autosomal dominant cancer syndrome which causes about 2-3% of cases of colorectal carcinoma. The development of LS is due to the genetic and epigenetic inactivation of genes involved in the DNA mismatch repair (MMR) system, causing an epiphenomenon known as microsatellite instability (MSI). Despite the fact that the genetics of the vast majority of MSI-positive (MSI+) cancers can be explained, the etiology of this specific subset is still poorly understood. As a possible new mechanism, it has been recently demonstrated that the overexpression of certain microRNAs (miRNAs, miRs), such as miR-155, miR-21, miR-137, can induce MSI or modulate the expression of the genes involved in LS pathogenesis. MiRNAs are small RNA molecules that regulate gene expression at the post-transcriptional level by playing a critical role in the modulation of key oncogenic pathways. Increasing evidence of the link between MSI and miRNAs in LS prompted a deeper investigation into the miRNome involved in these diseases. In this regard, in this study, we discuss the emerging role of miRNAs as crucial players in the onset and progression of LS as well as their potential use as disease biomarkers and therapeutic targets in the current view of precision medicine.

Depicting the landscape of gut microbial-metabolic interaction and microbial-host immune heterogeneity in deficient and proficient DNA mismatch repair colorectal cancers

BACKGROUND

Accumulating evidence has indicated the role of gut microbiota in remodeling host immune signatures, but various interplays underlying colorectal cancers (CRC) with deficient DNA mismatch repair (dMMR) and proficient DNA mismatch repair (pMMR) remain poorly understood. This study aims to decipher the gut microbiome-host immune interactions between dMMR and pMMR CRC.

METHOD

We performed metagenomic sequencing and metabolomic analysis of fecal samples from a cohort encompassing 455 participants, including 21 dMMR CRC, 207 pMMR CRC, and 227 healthy controls. Among them, 50 tumor samples collected from 5 dMMR CRC and 45 pMMR CRC were conducted bulk RNA sequencing.

RESULTS

Pronounced microbiota and metabolic heterogeneity were identified with 211 dMMR-enriched species, such as Fusobacterium nucleatum and Akkermansia muciniphila, 2 dMMR-depleted species, such as Flavonifractor plautii, 13 dMMR-enriched metabolites, such as retinoic acid, and 77 dMMR-depleted metabolites, such as lactic acid, succinic acid, and 2,3-dihydroxyvaleric acid. F. plautii was enriched in pMMR CRC and it was positively associated with fatty acid degradation, which might account for the accumulation of dMMR-depleted metabolites classified as short chain organic acid (lactic acid, succinic acid, and 2,3-dihydroxyvaleric acid) in pMMR CRC. The microbial-metabolic association analysis revealed the characterization of pMMR CRC as the accumulation of lactate induced by the depletion of specific gut microbiota which was negatively associated with antitumor immune, whereas the nucleotide metabolism and peptide degradation mediated by dMMR-enriched species characterized dMMR CRC. MMR-specific metabolic landscapes were related to distinctive immune features, such as CD8+ T cells, dendritic cells and M2-like macrophages.

CONCLUSIONS

Our mutiomics results delineate a heterogeneous landscape of microbiome-host immune interactions within dMMR and pMMR CRC from aspects of bacterial communities, metabolic features, and correlation with immunocyte compartment, which infers the underlying mechanism of heterogeneous immune responses.