Molecular insights into clinical trials for immune checkpoint inhibitors in colorectal cancer: Unravelling challenges and future directions

Colorectal cancer (CRC) is a complex disease with diverse etiologies and clinical outcomes. Despite considerable progress in development of CRC therapeutics, challenges remain regarding the diagnosis and management of advanced stage metastatic CRC (mCRC). In particular, the five-year survival rate is very low since mCRC is currently rarely curable. Over the past decade, cancer treatment has significantly improved with the introduction of cancer immunotherapies, specifically immune checkpoint inhibitors. Therapies aimed at blocking immune checkpoints such as PD-1, PD-L1, and CTLA-4 target inhibitory pathways of the immune system, and thereby enhance anti-tumor immunity. These therapies thus have shown promising results in many clinical trials alone or in combination. The efficacy and safety of immunotherapy, either alone or in combination with CRC, have been investigated in several clinical trials. Clinical trials, including KEYNOTE-164 and CheckMate 142, have led to Food and Drug Administration approval of the PD-1 inhibitors pembrolizumab and nivolumab, respectively, for the treatment of patients with unresectable or metastatic microsatellite instability-high or deficient mismatch repair CRC. Unfortunately, these drugs benefit only a small percentage of patients, with the benefits of immunotherapy remaining elusive for the vast majority of CRC patients. To this end, primary and secondary resistance to immunotherapy remains a significant issue, and further research is necessary to optimize the use of immunotherapy in CRC and identify biomarkers to predict the response. This review provides a comprehensive overview of the clinical trials involving immune checkpoint inhibitors in CRC. The underlying rationale, challenges faced, and potential future steps to improve the prognosis and enhance the likelihood of successful trials in this field are discussed.

Long-term response with the atypical reaction to nivolumab in microsatellite stability metastatic colorectal cancer: A case report

Immunotherapy has become an integral part of a comprehensive treatment approach to metastatic colorectal cancer (mCRC). Nivolumab (Opdivo) is a human immunoglobulin G4 monoclonal antibody that blocks the interaction between the programmed cell death 1 (PD-1) receptor and its ligands 1/2 (PD-L1/PD-L2), leading to inhibition of T-cell proliferation, cytokine secretion, and enhanced immune response. The US Food and Drug Administration (FDA) has approved this drug for use in high microsatellite instability (MSI-high)/deficiencies in mismatch repair (dMMR) advanced CRC patients. However, its efficacy is extremely limited in microsatellite stability (MSS)/mismatch repair proficient (pMMR) patients. We report a case of a 42-year-old man diagnosed with MSS/pMMR mCRC who has achieved a durable response to nivolumab after a progression under chemotherapy with antiangiogenic treatment. We observed for the first time an atypical response after 8 months of nivolumab treatment, with the regression of previous primary pulmonary lesions and the presence of new para-aortic lymph node lesions. This report demonstrates that a subset of pretreated mCRC patients with the MSS/pMMR phenotype may benefit from nivolumab and these patients need more attention.

Application of sintilimab combined with anlotinib hydrochloride in the clinical treatment of microsatellite stable colorectal cancer

BACKGROUND

Microsatellite stable (MSS) colorectal cancer (CRC) is a common type of tumor with limited treatment options. Sintilimab and anlotinib hydrochloride are two extensively studied anticancer drugs.

AIM

To probe the clinical value of combining sintilimab with anlotinib hydrochloride in MSS CRC treatment.

METHODS

During the period spanning from April 2019 to April 2022, Zhejiang Provincial People’s Hospital accommodated a cohort of 92 patients diagnosed with MSS CRC who were classified into two distinct groups in our study, the observation group and the control group. The control group was administered anlotinib hydrochloride as their designated therapy, whereas the observation group received the additional treatment of sintilimab in conjunction with the therapy assigned to the control group. The administration of treatment occurred in cycles consisting of a duration of 3 wk, and the evaluation of effectiveness took place subsequent to the completion of two consecutive cycles of treatment within both groups. A comparative analysis between the two groups was conducted to assess the short-term efficacy and ascertain the incidence of adverse events transpiring throughout the duration of the treatment period. Changes in the levels of carcinoembryonic antigen, carbohydrate antigen 199 (CA199), CA125, and T cell subsets (CD4+, CD8+, CD4+/CD8+) as well as the assessment of the quality of life using the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire-Core 30 were compared between the two groups prior to and subsequent to therapy. Finally, a 1-year follow-up was conducted for both groups of patients, and the survival status was recorded and analyzed.

RESULTS

The short-term effectiveness displayed by the observation group surpassed that exhibited by the control group, with a statistically significant discrepancy (76.09% vs 50.00%), reaching a significance level denoted as P < 0.05. Following the administration of treatment, the observation group manifested a considerable reduction in numerous serum indicators, which were found to be lower than the corresponding pretreatment levels within the same group as well as the post-treatment levels observed in the control group (P < 0.05). Post-treatment, the T lymphocyte subset levels within the observation group demonstrated a remarkable amelioration, surpassing the corresponding pre-treatment levels observed within the same group as well as the post-treatment levels observed in the control group (P < 0.05). Subsequent to the therapeutic intervention, the observation group showcased a notable amelioration in the scores associated with multiple dimensions of life quality. These scores outperformed the pretreatment scores within the same group as well as the post-treatment scores observed in the control group (P < 0.05). The safety levels of drug use in the two group were comparable (19.57% vs 13.04%), and no distinct difference was observed upon comparison (P > 0.05). After the completion of treatment, both groups of patients underwent a 1-year follow-up outside the hospital. Throughout this period, 1 patient within the observation group and 2 patients within the control group became untraceable and were lost to follow-up. During the follow-up period of the observation group, 12 patients died, resulting in a survival rate of 73.33% (33/45), while in the control group, 21 patients died, resulting in a survival rate of 52.27% (23/44). The implementation of Kaplan-Meier survival analysis revealed a conspicuous contrast in survival rates exhibited by the two groups (log-rank = 4.710, P = 0.030).

CONCLUSION

The combination of sintilimab and anlotinib hydrochloride demonstrated favorable efficacy in the treatment of MSS CRC patients, leading to improvements in patient immunity and prognosis. Additionally, it exerted inhibitory effects on the expression of carcinoembryonic antigen, CA199, and CA125.

Medullary carcinoma of the colon: A comprehensive analysis of the National Cancer Database

PURPOSE

Medullary carcinomas (MC) of the colon are uncommon tumors. In this study, we analyzed demographic and disease characteristics as well as survival outcomes of MC versus undifferentiated (UDA) and poorly differentiated (PDA) adenocarcinomas (AC) of the colon.

MATERIALS AND METHODS

The National Cancer Database (2004-2018) was utilized to identify patients with colon cancer. Patient demographics (including age, gender, race), disease characteristics (including grade, TNM stage, carcinoembryonic levels, perineural and lymphovascular invasion, lymph node status, microsatellite stability, KRAS mutation, and primary tumor site), and facility type and location were evaluated. Chi-square tests were used to compare descriptive data. Cox Regression and Kaplan Meier analyses were used to analyze survival characteristics.

RESULTS

1,041,753 patients with colon cancer were identified of whom 2709 patients had MC and 897,902 had AC (136,597 PDA and 18,042 UDA). MC was seen in older patients (mean age 74 ± 13 years) and women (72.5% vs. 27.5% males). Most MCs were poorly differentiated (63.3%), and 82.4% of patients with MC had microsatellite instability. Fewer patients with MC had perineural invasion (15.6% vs. 22.0% in PDA and 22.4% in UDA, p < 0.001) and positive lymph nodes (38.4% versus 59.9% with PDA and 59.7% with UDA, p < 0.0001). MC diagnosis increased by year (Cochran-Armitage trend test, p < 0.0001). Kaplan Meir analysis revealed a better prognosis for patients with MC when compared to PDA or UDA (p < 0.001).

CONCLUSION

Given the rarity, pathologists should maintain a high suspicion for MC when encountering poorly differentiated or undifferentiated right-sided colon cancer with associated MSI-H.

[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.

Strategic enhancement of immune checkpoint inhibition in refractory Colorectal Cancer: Trends and future prospective

Colorectal cancer (CRC), known as a frequently fatal disease, ranking as the third most common malignancy, is the second leading cause of cancer related mortality worldwide. Metastases are common in CRC patients which account for approximately 25% of the patients at diagnosis, 50% of patients during treatment which is associated closely with CRC mortality. Conventional therapies such as surgery, chemotherapy, and radiotherapy are standards of care for the treatment of CRC patients. However, primary tumor recurrence and secondary disease in patients receiving standard of care treatment modalities occur in 50% of patients so that new treatment modalities are needed. Immune checkpoint inhibition (ICI) has transformed the management of patients suffered from metastatic CRC (mCRC) with mismatch repair deficiency (dMMR) and microsatellite instability (MSI) -high (MSI-H) while manifests ineffectiveness in preserved mismatch repair (pMMR) or microsatellite stable (MSS) "cold" tumors which makes up the majority (95%) of mCRC. In this review, we mainly lay emphasis on the development of combinations in therapy strategies with ICIs with other immune based treatment approaches to increase the intra-tumoral immune response and render tumors 'immune-reactive', thereby increasing the efficacy of tumor immunotherapy.

Tumor-derived mutations in postoperative plasma of colorectal cancer with microsatellite instability

The mutation in postoperative plasma (molecular residues) was an independently prognostic factor in colorectal cancer (CRC). The status of postoperative plasma mutation of microsatellite instability (MSI) CRC has not been systematically examined. In this study, we enrolled 30 MSI and 46 microsatellite stability (MSS) CRCs, and performed next generation sequencing on surgical tissues, postoperative plasma, and plasma during follow-up. Compared with MSS, MSI tumors had dissimilar genomic profiles, higher tumor mutation burden (TMB), and more frameshift mutations. In the postoperative plasma, more MSI CRCs were detected with tumor-derived mutations (77% in MSI vs 33% in MSS, p < 0.001). The numbers of postoperative mutations were proportional to MSI tissues (Spearman r = 0.47, p = 0.023), while not for MSS. More proportion of postoperative plasma samples of MSI CRCs harbored frameshift mutations than MSS (p = 0.007). For the follow-up plasma, 93% (14 out of 15) MSI CRCs harbored tumor-derived mutations; 33% (4/12) MSS were mutation-positive, lower than MSI (p = 0.003). Thus, considering that MSI CRC had extremely distinct mutational characteristics in tumor and postoperative plasma compared with MSS CRC, we propose that the prognostic value of molecular residue identification in postoperative plasma needs to be independently evaluated in MSI and MSS CRCs.

Regorafenib and Nivolumab or Pembrolizumab Combination and Circulating Tumor DNA Response Assessment in Refractory Microsatellite Stable Colorectal Cancer

BACKGROUND

Metastatic colorectal cancers (MCRCs) with microsatellite stability (MSS) are resistant to immunotherapy with programmed cell death protein 1 (PD-1) and programmed death-ligand 1 inhibitors. However, the addition of regorafenib to nivolumab was recently associated with a high response rate and a protracted progression-free survival in a small cohort of MSS Japanese patients with metastatic colorectal cancer.

MATERIALS AND METHODS

We evaluated the outcome of patients with MSS metastatic colorectal cancer who were treated on a compassionate basis with PD-1 inhibitors in combination with regorafenib in a single U.S. center.

RESULTS

A total of 18 patients were treated with a combination of regorafenib and PD-1 inhibitors. No treatment-related grade 3 or above toxicities were noted. Thirteen patients (69%) had progressive disease, and five patients (31%) experienced stable disease as best response. Four out of five stable diseases occurred in patients without liver metastases, whereas only 1 of 14 patients with history of liver metastases had a short disease stabilization. A rise in circulating tumor DNA (ctDNA) at the 4-week time pointuniversally predicted tumor progression at 2 months, whereas a decline was associated with radiographic disease stabilization.

CONCLUSIONS

Regorafenib and nivolumab combination was associated with modest clinical activity in patients with MSS chemotherapy-resistant metastatic colorectal cancer. Selection for patients without history of liver metastases may identify a cohort of patients with MSS colorectal cancer with a higher likelihood of benefit from this combination. ctDNA may represent a powerful tool for predicting early therapeutic efficacy of immunotherapy in the MSS colorectal cancer population.

IMPLICATIONS FOR PRACTICE

This study showed that the combination of regorafenib and nivolumab was associated with a modest clinical activity in patients with advanced microsatellite stability (MSS) metastatic colorectal cancer. This combination should be avoided in clinical practice, especially in patients with MSS colorectal cancer with liver metastases. Further investigation of regorafenib plus PD-1 inhibitors should be considered in MSS colorectal cancer without liver metastases.

Adenosquamous carcinoma of the right colon with diffuse signet-ring mucinous component

Colorectal carcinoma is one of the most frequent human malignant neoplasms. Besides the most common histological types, colorectal adenosquamous carcinoma is very rare, being microscopically constituted by tumoural glandular and squamous components. The diagnosis of primary colon adenosquamous carcinoma requires the exclusion of a metastatic squamous cell carcinoma and the extension of a primary squamous cell carcinoma from the anal-rectum junction. We report a case of primary adenosquamous carcinoma of the ascending colon in a 62-year-old Caucasian man affected by long-standing ulcerative colitis. Peritumoural lymph nodes and distant metastasis were present. We reported also a diffuse signet-ring mucinous component, which has not been previously observed. Moreover, we investigated microsatellite and all-RAS/B-RAF status, p16 and p53 protein expression, and the molecular presence of human papillomavirus DNA in all the morphologically distinct components, in order to suggest pathogenetic factors influencing the aggressive prognosis of colon adenosquamous carcinoma.

Case report: mismatch repair proficiency and microsatellite stability in gastric cancer may not predict programmed death-1 blockade resistance

Background

Anti-programmed death-1 therapy has poor efficacy in mismatch repair-proficient (pMMR) colorectal cancers; however, its efficacy in pMMR gastric cancers remains undetermined. Here, we report the case of a patient with pMMR and microsatellite-stable gastric cancer who exhibited a partial response to salvage anti-programmed death-1 therapy with pembrolizumab.

Case presentation

Initially, the patient underwent subtotal gastrectomy 4 years ago for early-stage gastric cancer (pT1bN2M0, stage IIA). Immunohistochemical analysis of the tumor revealed strongly positive for HER2/neu. He had received trastuzumab plus pertuzumab, cisplatin, and capecitabine for recurrent tumors since September 2014 for 15 cycles. Disease progression of gastric cancer was found in August 2015. Since September 2015, the patient has received pembrolizumab monotherapy (200 mg as a fixed dose, every 3 weeks) for 3 months and the repeat computed tomography demonstrated a confirmed partial response. The plasma carcinoembryonic antigen also decreased dramatically. Both immunohistochemistry and a polymerase chain reaction-based method revealed that the patient had pMMR gastric cancer.

Conclusions

This case report provides the first report that mismatch repair-proficient and microsatellite-stable gastric cancers can respond well to anti-PD-1 monotherapy and indicates both markers may not sufficiently be predictive of anti-PD-1 therapy resistance in gastric cancer.