Correlation between circulating tumor DNA and carcinoembryonic antigen levels in patients with metastatic colorectal cancer

Background

Circulating tumor DNA (ctDNA) is a biomarker with potential to reflect comprehensive genomic information and overcome intratumor heterogeneity. In contrast, carcinoembryonic antigen (CEA) is a conventional tumor marker for predicting recurrence, survival, and chemotherapeutic efficacy in patients with metastatic colorectal cancer (mCRC). However, the relationship between them remains unclear. Here, the relationship between plasma ctDNA and CEA levels was evaluated to clarify the advantages and disadvantages of their clinical use.

Methods

A total of 110 patients with mCRC underwent chemotherapy were enrolled. Amplicon‐based plasma genomic profiling of 14 genes that are commonly mutated in CRC by next‐generation sequencing was compared to the CEA level and tumor diameter using Spearman’s correlation coefficient.

Results

The overall concordance rate between the ctDNA and CEA levels was 75.5% (83/110). The correlation coefficient between the ctDNA and CEA levels was lower in the group of patients without liver and lymph node metastases (r = 0.18, p = 0.44) than in the group of patients with liver metastasis (r = 0.48, p < 0.0001). Although the correlation coefficients between tumor diameter and both ctDNA and CEA levels were high in the group of patients with liver metastasis, only the CEA correlation coefficient was maintained in the group of patients without liver and lymph node metastases (r = 0.53, p = 0.01). The characteristics that influenced discordance were liver metastasis and the sum of tumor diameter.

Conclusions

The status of ctDNA and CEA may not be consistent in patients with mCRC without liver metastasis or with a low tumor volume; both results should be considered when deciding a treatment strategy.

Association Between Regorafenib Dose and Efficacy Against Metastatic Colorectal Cancer in a Real-World Setting

The association between regorafenib dosage in the treatment of metastatic colorectal cancer (mCRC) and efficacy is currently not well established. It was previously reported that the regorafenib dose as prescribed is associated with efficacy, but doses in actual clinical settings have not been analyzed. We retrospectively analyzed patients with mCRC who had received regorafenib as third-line or later chemotherapy between May 2013 and June 2018. Patients who were not treated in the Pharmaceutical Outpatient Clinic for compliance assessment were excluded. Overall survival was calculated using the Kaplan-Meier method. Prognostic factors, including baseline demographics and adverse events, were evaluated using Cox proportional hazard models. A total of 176 patients were enrolled. By multivariate analysis, total dose until the second cycle < 3180 mg (HR = 1.71, 95% CI, 1.20-2.44, P = .003) was one of independent negative predictors of overall survival. Median survival times of the lower-dose group (< 3180 mg) and higher-dose group (≥ 3180 mg) were 5.8 and 7.6 months, respectively (P = .045). The cumulative dose of regorafenib until the second cycle in patients with mCRC was associated with survival. It is important to individualize regorafenib dose in mCRC patients.

Circulating Tumor DNA Analysis Detects FGFR2 Amplification and Concurrent Genomic Alterations Associated with FGFR Inhibitor Efficacy in Advanced Gastric Cancer

PURPOSE

FGFR2 amplification is associated with poor prognosis in advanced gastric cancer and its subclonal heterogeneity has been revealed. Here, we examined whether circulating tumor DNA (ctDNA) was useful for detecting FGFR2 amplification and co-occurring resistance mechanisms in advanced gastric cancer.

EXPERIMENTAL DESIGN

We assessed genomic characteristics of FGFR2-amplified advanced gastric cancer in a nationwide ctDNA screening study. We also analyzed FGFR2 amplification status in paired tissue and plasma samples with advanced gastric cancer. In addition, we examined patients with FGFR2-amplified advanced gastric cancer identified by ctDNA sequencing who received FGFR inhibitors.

RESULTS

FGFR2 amplification was more frequently detected by ctDNA sequencing in 28 (7.7%) of 365 patients with advanced gastric cancer than by tissue analysis alone (2.6%-4.4%). FGFR2 amplification profiling of paired tissue and plasma revealed that FGFR2 amplification was detectable only by ctDNA sequencing in 6 of 44 patients, which was associated with a worse prognosis. Two patients in whom FGFR2 amplification was detected by ctDNA sequencing after tumor progression following previous standard chemotherapies but not by pretreatment tissue analysis had tumor responses to FGFR inhibitors. A third patient with FGFR2 and MET co-amplification in ctDNA showed a limitation of benefit from FGFR inhibition, accompanied by a marked increase in the MET copy number.

CONCLUSIONS

ctDNA sequencing identifies FGFR2 amplification missed by tissue testing in patients with advanced gastric cancer, and these patients may respond to FGFR inhibition. The utility of ctDNA sequencing warrants further evaluation to develop effective therapeutic strategies for patients with FGFR2-amplified advanced gastric cancer.

Effect of neutropenia on survival outcomes of patients with metastatic colorectal cancer receiving trifluridine/tipiracil plus bevacizumab

Trifluridine (FTD)/tipiracil (TPI) plus bevacizumab (Bev) is a promising late-line treatment in metastatic colorectal cancer (mCRC). Although chemotherapy-induced neutropenia (CIN) is a well-known predictor of FTD/TPI efficacy, whether CIN is a predictive marker of efficacy for FTD/TPI + Bev remains unclear. Thus, the present study aimed to investigate the clinical outcomes of FTD/TPI + Bev and the predictive markers of its efficacy. Clinical data of patients with mCRC who received FTD/TPI + Bev at the Cancer Institute Hospital between January 2017 and August 2020 were retrospectively collected. Disease control rate (DCR), progression-free survival (PFS), overall survival (OS) and safety were assessed. In addition, subgroup analyses of prognostic and predictive efficacy markers were performed. In total, 94 patients (median age, 60.0 years; age range, 32–82 years; 37 men and 57 women) were included in the present study. The DCR was 44.7%, the median PFS time was 2.9 months (2.3–4.1 months) and the median OS time was 10.0 months (7.3–11.1 months). Grade 3 or 4 CIN within the first cycle of treatment occurred in 27.7% of patients, which was significantly associated with a longer PFS time than those who did not develop CIN [3.8 months (2.3–8.4 months) vs. 2.7 months (1.8–4.0 months); P=0.008]. Furthermore, the DCR was higher in patients with grade 3 or 4 CIN within the first cycle of treatment than those without CIN (61.5 vs. 38.2%; P=0.07). Multivariate Cox regression analysis revealed that grade 3 or 4 CIN within the first cycle of treatment are independent predictors for a longer PFS time (P=0.01). Taken together, the results of the present study suggest that grade 3 or 4 CIN within the first cycle of treatment are early predictors of the efficacy of FTD/TPI + Bev.

Clinical Impact of Primary Tumor Location and RAS, BRAF V600E, and PIK3CA Mutations on Epidermal Growth Factor Receptor Inhibitor Efficacy as Third-line Chemotherapy for Metastatic Colorectal Cancer

BACKGROUND/AIM

Primary tumor location and RAS and BRAF V600E mutations are predictors of the efficacy of epidermal growth factor receptor (EGFR) inhibitors. However, there are limited reports on their effects on the outcomes of third-line chemotherapy with EGFR inhibitors in metastatic colorectal cancer (mCRC) patients.

PATIENTS AND METHODS

We retrospectively collected the clinical data of KRAS exon 2 wild type (WT) mCRC patients treated with EGFR inhibitor monotherapy or EGFR inhibitor plus irinotecan as third-line chemotherapy. The association between primary tumor location, RAS (KRAS exon 3, 4 or NRAS), BRAF V600E, and PIK3CA mutational status, and treatment outcome was evaluated.

RESULTS

A total of 72 patients were included in this study. In multivariate analysis, RAS (p=0.004) and BRAF mutations (p=0.00008) were independent factors for shorter PFS. Poor performance status (p=0.01) and BRAF mutation (p=0.00002) were independent factors for shorter OS, whereas primary tumor location and PIK3CA mutation did not influence survival.

CONCLUSION

Additional analysis of RAS and BRAF mutations could contribute to the selection of patients who are likely to benefit from third-line EGFR inhibitors, regardless of primary tumor location.

Single-institute comparison of the efficacy of systemic chemotherapy for oesophagogastric junction adenocarcinoma and stomach adenocarscinoma in a metastatic setting

BACKGROUND

Different approaches are used to treat resectable tumours in patients having adenocarcinoma at the oesophagogastrointestinal junction (EGJ) or in the stomach. However, there is limited information about treatment efficacy for patients at metastatic stage. A recent molecular analysis of upper gastrointestinal tract adenocarcinoma revealed that the anatomical location can influence the molecular backgrounds of tumours. This study sought to elucidate whether different therapeutic approaches should be used for EGJ tumours relative to those in the stomach.

METHODS

This retrospective cohort study was conducted at a single institute in Japan. Patients having metastatic or recurrent adenocarcinoma in the EGJ or stomach who underwent platinum doublet chemotherapy between January 2007 and August 2014 were enrolled. Patients in the EGJ tumour group had tumours having an epicentre within 2 cm proximal or 5 cm distal to the estimated anatomical EGJ and cardia.

RESULTS

Among 378 consecutively enrolled patients, 61 were grouped into the EGJ group and the remainder comprised the stomach group. The EGJ group had more men and lower incidence of diffuse type and Borrmann type IV tumours and peritoneum metastasis compared with the stomach group. The median overall survival of patients in the EGJ and stomach groups was similar (17.3 months (95% CI 13.5 to 23.2) vs 14.5 months (95% CI 13.3 to 16.4)). No statistically significant difference was observed in progression-free survival. Although the overall postprogression survival differed significantly between the EGJ and stomach groups (8.2 months (95% CI 5.7 to 12.7) vs 7.1 months (95% CI 6.1 to 7.8)), on grouping patients by histological type, the two groups exhibited similar postprogression survival. Multivariate analysis demonstrated that diffuse-type histology, higher serum CA19-9 levels and neutrophil to lymphocyte ratios were independent poor prognostic factors.

CONCLUSIONS

Different clinicopathological features of EGJ adenocarcinoma were not associated with clinical outcomes of platinum doublet chemotherapy. Histological subtype rather than anatomical location has more significance for treatment decisions for advanced gastric cancers.

REMARRY and PURSUIT trials: liquid biopsy-guided rechallenge with anti-epidermal growth factor receptor (EGFR) therapy with panitumumab plus irinotecan for patients with plasma RAS wild-type metastatic colorectal cancer

BACKGROUND

Previous clinical trials have demonstrated the potential efficacy of rechallenge with anti- epidermal growth factor receptor (EGFR) monoclonal antibodies (mAbs) for patients with RAS/BRAF V600E wild-type metastatic colorectal cancer (mCRC). Moreover, post hoc biomarker analyses of clinical trials has suggested that RAS status in circulating tumor DNA (ctDNA) has a high probability to select patients who could benefit from anti-EGFR mAb rechallenge.

METHODS

This trial is composed of 2 phases: a monitoring phase (REMARRY) and a trial phase (PURSUIT). A monitoring phase, the REMARRY study, aims to evaluate the dynamics of plasma RAS status during the subsequent treatments after refractory to anti-EGFR therapy in patients with mCRC with RAS/BRAF V600E wild-type tumors who have progressed after a response to previous anti-EGFR therapy, using a highly sensitive digital polymerase chain reaction OncoBEAM RAS CRC kit in a central laboratory (Sysmex, Japan). A trial phase, the PURSUIT trial, is a multicenter, single-arm phase II trial to assess the efficacy and safety of rechallenge therapy with panitumumab plus irinotecan in patients without RAS mutations in ctDNA (plasma RAS negative) in the REMARRY study. Key eligibility criteria of the PURSUIT trial include RAS/BRAF V600E wild-type mCRC in tumor tissue refractory or intolerant to fluoropyrimidine, oxaliplatin, and irinotecan; progression after complete or partial response to previous anti-EGFR therapy; plasma RAS negative (defined as plasma mutant allele frequencies [MAF] of all RAS ≤ 0.1%) within 28 days prior to enrollment; 4 months or more between the last administration of previous anti-EGFR mAb and the start of protocol treatment; and Eastern Cooperative Oncology Group (ECOG) Performance Status (PS) ≤ 1. The primary endpoint is the confirmed objective response rate (ORR). The target sample size of the PURSUIT trial is 50 patients. Biomarker analyses will be performed in parallel using the OncoBEAM RAS CRC kit and a next-generation sequencing-based ctDNA analysis (Guardant360).

DISCUSSION

Our trial aims to confirm the clinical benefit of anti-EGFR mAb rechallenge therapy in patients with plasma RAS negative. Moreover, through biomarker analyses, our trial will shed light on which patients would benefit from rechallenge in addition to being plasma RAS negative.

TRIAL REGISTRATION

The REMARRY study: UMIN, UMIN000036424 . Registered date: April 5, 2019. The PURSUIT trial: jRCT, jRCTs031190096 . Registered date: October 1, 2019.

[FOLFIRI plus Ramucirumab Treatment for Metastatic Colorectal Cancer-Narrative Review of Real-World Evidence in Japan]

To assess the efficacy and safety of ramucirumab in combination with FOLFIRI in patients with unresectable metastatic colorectal cancer under clinical practice in Japan, we reviewed manuscripts reporting clinical research, including case reports, of Japanese patients with FOLFIRI plus ramucirumab therapy published starting from 2016, when ramucirumab was approved as a treatment for metastatic colorectal cancer in Japan, to June 2020. We also reviewed an interim report of post-marketing surveillance study. The efficacy of ramucirumab in combination with FOLFIRI including irinotecan 150 mg/m2, which is the recommended dose in Japan and is used as initial dose in Japanese clinical practice, was similar to that of the global, phase 3 RAISE study with irinotecan 180 mg/m2. The desirable effect of FOLFIRI plus ramucirumab was observed in patients with wild-type RAS, primary tumors on the left sides(descending, sigmoid, or rectum colons), or who received anti-epidermal growth factor receptor agents, including panitumumab or cetuximab, as previous treatment. Also, the effectiveness of FOLFIRI plus ramucirumab as a late-line treatment was suggested. Several patients were reported to have nephrosis syndrome after starting ramucirumab, but they recovered with discontinuation of ramucirumab and appropriate treatment. No new safety concerns were observed from the literature or the interim report of post-marketing surveillance study.

Discovery of a potential predictive marker for eribulin treatment and novel target genes in BRAF V600E mutant metastatic colorectal cancer using an AI-driven RNA-seq analysis platform: Translational research of the BRAVERY study (EPOC1701)

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Background: Patients (pts) with BRAF V600E mutant (mt) metastatic colorectal cancer (mCRC) still have a poor prognosis even when treated with encorafenib plus cetuximab. We reported that eribulin that inhibits G2-M cell cycle had limited activity for these pts in the phase II BRAVERY study (Masuishi T, et al. WCGC 2020). Barras D, et al. (2017) reported that BRAF V600E mt mCRCs were classified into BM1 and BM2 characterized by KRAS/AKT pathway activation and deregulation of the cell cycle with G2-M phase activation, respectively, based on gene expression. Methods: Whole transcriptome RNA-seq of FFPE pre-treatment tumor samples was performed using NovaSeq 6000 in the BRAVERY study. Molecular features were extracted using the Txome.ai platform (Ocean Genomics Inc., PA, USA) which included transcript- and gene-level expression quantification, expression-based clustering, and structural variant calling. Efficacy of eribulin was classified as “good” if pts had a tumor reduction and/or progression-free survival (PFS) of more than 6 months, and “poor” otherwise. The differential gene expression analysis was performed between pts with “good” and “poor” using Txome.ai. In addition, BM and consensus molecular subtype (CMS) classification were performed using the model developed by Barras D, et al. (2017) and Guinney J, et al. (2015), respectively. Results: Among 27 pts, 26 tumor samples were available to perform RNA-seq and analyze gene expression despite low mapping rates. Patient characteristics were as follows: median age of 58.5 (range, 33–71) years; ECOG PS of 0/1 (16/10); primary tumor location of right/left (11/15); and all 26 pts had MSS/pMMR. Four and 22 pts were classified into “good” and “poor” groups, respectively. Among 52 differentially expressed genes (GENCODE v31) with false discovery rate-adjusted P- value < 0.05, the top 5 genes with the lowest P-values are provided in the table. All 4 pts in the “good” group were classified into BM2 and pts in the “poor” group were classified into BM1 (8/22) and BM2 (14/22) (p = 0.07). In addition, all but 2 pts were classified into CMS4. These two pts belong to the “poor” group with one of them classified into CMS1 and the other into CMS2. Conclusions: These gene expression analyses suggest that BM2 subtype could be a predictive marker for the efficacy of eribulin and some genes could be novel targets with the goal to improve prognosis of pts with BRAF V600E mt mCRC. This is the first finding for a potential biomarker in this subgroup using RNA-seq analysis tools. These findings will require additional validation. Clinical trial information: UMIN000031552. [Table: see text]

Impact of a metastatic site on circulating tumor DNA (ctDNA) analysis in patients (pts) with metastatic colorectal cancer (mCRC)

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Background: ctDNA genotyping has been used as an alternative to tissue genotyping for precision oncology. In mCRC, although low plasma RAS variant allelic frequencies (VAFs) and low concordance with tissue RAS tests have been reported in pts with lung-only metastasis (mets) (Kagawa Y. et al., Clin Cancer Res 2021), the association of ctDNA identified using the next-generation sequencing method with metastatic sites is still unknown. Methods: We investigated the association between metastatic site and ctDNA detection by using the Guardant360 (G360), a ctDNA assay which detects 74 gene alterations including mutations with the 95% of limit of detection of 0.2%, in mCRC pts with single organ mets in pts who had not received anti-EGFR therapy in the SCRUM-Japan GOZILA study. We also evaluated the correlations between the size/number of mets by CT and detected VAFs. Results: Of 1187 mCRC pts enrolled in GOZILA, 138 pts (49 with liver-only, 15 with lymph node-only, 27 with peritoneum-only, and 47 with lung-only mets) were eligible for this study. The concordance of RAS/ BRAF status between G360 and tissue in-vitro diagnostic tests were 93.9% in liver-only, 80.0% in lymph node-only, 56.0% in peritoneum-only, and 65.9% in lung-only mets. The median maximum VAF (maxVAF) corresponding to the highest ctDNA fraction and the median numbers of detected variants were 23.1% and 5 in liver-only, 6.0% and 5 in lymph node-only, 0.4% and 3 in peritoneum-only, and 0.4% and 3 in lung-only (all P<0.001, Kruskal-Wallis test). A few pts with liver-only (2.0%) and lymph node-only mets (13.3%) had a maxVAF of <0.2%, but maxVAF was more frequently <0.2% in pts with lung-only (27.7%) or peritoneum-only mets (29.6%), especially in those with lung-only mets <20 mm as the longest diameter and <20 lesions (69.2%) or with peritoneum-only mets <20 mm as the longest diameter (87.5%). Conclusions: Lung-only and peritoneum-only mets had significantly lower maxVAF and lower numbers of detected variants, suggesting lower detections of subclonal variants. To ensure the sufficient clinical performance in G360 assay, inclusion of pts with lung-only mets ≥20 mm of longest diameter and/or ≥20 lesions, and ≥20 mm of the longest diameter in pts with peritoneum-only mets may be required.[Table: see text]

Outcomes of Surgical Treatment for Patients with Anorectal Malignant Melanoma; Results of Nine Cases in a Single Institution

Anorectal melanoma (AM) is a rare and aggressive malignancy. Two main types of surgical approach for AM are abdominoperineal resection (APR) and wide local excision (WLE). Nine patients with AM underwent surgical treatment between July 2005 and October 2017 at our institution. Two of the patients were diagnosed with localized stage, four with regional stage, and three with distant stage. Laparoscopic APR was performed in six patients with localized and regional stages, whereas palliative APR and/or WLE were performed in those with distant metastasis. Both patients with localized stage lived without relapse for 6.8 years after surgery. One of the patients with regional stage had no relapse during 3.6 years of follow-up. The other three patients had recurrence and died between 6 and 32 months after surgery. The median overall survival (OS) of the cohort was 14.8 months, and the 5- and 10-year OS were 33.3% and 16.7%, respectively. The tumor at the regional stage could be removed through WLE, but preoperative diagnosis of lymph node metastasis is difficult in patients with AM. Further development of the diagnostic method is expected, and future tasks will be to establish the selection criteria to determine which surgical approach is optimal for this devastating disease.

Associations among plasma concentrations of regorafenib and its metabolites, adverse events, and ABCG2 polymorphisms in patients with metastatic colorectal cancers

PURPOSE

The association between the pharmacokinetics and pharmacodynamics of regorafenib, a multiple tyrosine kinase inhibitor, remains unclear. This study assessed the trough plasma concentrations (C_trough) of regorafenib and its N-oxide (M2) and N-oxide/desmethyl (M5) metabolites, and evaluated the associations among these levels, adverse events, and pharmacokinetic-related genetic polymorphisms in patients with metastatic colorectal cancer.

METHODS

The C_trough levels of regorafenib and its metabolites were assessed in a single-center, prospective, observational study, 7 days after the initial treatment. The correlation between those values and adverse events was then examined. In addition, the genetic polymorphisms of ABCG2, SLCO1B1, and UGT1A9 were determined and evaluated for associations with the levels of regorafenib, M2, and M5.

RESULTS

We analyzed 43 patients who received regorafenib 40-120 mg/day; among them, 35 patients started at 120 mg/day. With regard to bilirubin increase, the C_trough values of regorafenib were significantly higher in the group with grade ≥ 2 than in groups with grades 0 and 1 (p = 0.010). The M5 C_trough levels were significantly associated with the severity of hypertension or rash (p < 0.05). In a multivariate analysis, the M5 C_trough values and age were significant predictors of severe rash. Lastly, significant differences were noted in the M5 concentration-to-dose ratio values between the patients with ABCG2 421A/A and ABCG2 421C/A or C/C polymorphisms (p = 0.035).

CONCLUSION

This study showed that the C_trough of regorafenib was associated with bilirubin increase, and also clarified for the first time that the C_trough of M5 was significantly correlated with hypertension and severe rash.

Treatment sequences of patients with advanced colorectal cancer and use of second-line FOLFIRI with antiangiogenic drugs in Japan: A retrospective observational study using an administrative database

The objectives were to describe treatment sequences for advanced colorectal cancer (CRC), use of second-line FOLFIRI (leucovorin, 5-fluorouracil, irinotecan) plus antiangiogenic drug (bevacizumab, ramucirumab, aflibercept beta) therapy, and the factors associated with the duration of antitumor drug treatment from second-line antiangiogenic therapy in Japan. This retrospective observational study was conducted using a Japanese hospital-based administrative database. Patients were enrolled if they started adjuvant therapy (and presumably experienced early recurrence) or first-line treatment for advanced CRC between May 2016 and July 2019, and were analysed until September 2019. Factors associated with overall treatment duration from second-line treatment with FOLFIRI plus antiangiogenic drugs were explored with multivariate Cox regression analysis. The most common first-line treatments were FOLFOX (leucovorin, 5-fluorouracil, oxaliplatin) or CAPOX (capecitabine, oxaliplatin) with bevacizumab (presumed RAS-mutant CRC) and FOLFOX with panitumumab (presumed RAS-wild type CRC). The most common second-line treatments were FOLFIRI-based. Many patients did not transition to subsequent lines of therapy. For second-line treatment, antiangiogenic drugs were prescribed more often for patients with presumed RAS-mutant CRC, right-sided CRC, and independent activities of daily living (ADL). The median duration of second-line FOLFIRI plus antiangiogenic drug treatment was 4.5 months; 66.2% of patients transitioned to third-line therapy. Low body mass index and not fully independent ADL were significantly associated with shorter overall duration of antitumor drug treatment from second-line therapy. Left-sided CRC, presumed RAS-wild type CRC, previous use of oral fluoropyrimidines and use of proteinuria qualitative tests, antihypertensives, or anticholinergics during second-line therapy were significantly associated with longer treatment. Treatment of advanced CRC in Japan is consistent with both international and Japanese guidelines, but transition rates to subsequent therapies need improvement. In addition to antitumor drug treatment, better ADL, higher body mass index, management of hypertension, and proteinuria tests were associated with continuation of sequential therapy that included antiangiogenic drugs.

Immunotherapy in Colorectal Cancer: Current and Future Strategies

Despite the recent advances in the systemic treatment of metastatic colorectal cancer (mCRC), prognostic outcomes have remained to be poor. Thus, what is needed is an innovative treatment approach. Immune checkpoint inhibitors (ICIs) targeting programmed death-1 (PD-1) and anti-programmed cell death ligand 1 (PD-L1) have exhibited a durable response and dominated the treatment of various tumor types. However, in mCRC, the clinical benefit is limited in patients with deficient mismatch repair (dMMR)/high levels of microsatellite instability (MSI-H), comprising approximately 5% of mCRC cases, and some do not respond to ICI treatment. Thus, further research is needed to identify predictive biomarkers. The most urgent need is developing effective immunotherapy for patients with proficient mismatch repair (pMMR)/microsatellite stable (MSS) cancer, which comprises 95% of mCRC cases. Tumors with the pMMR/MSS phenotype often exhibit a lower tumor mutation burden and fewer tumor-infiltrating lymphocytes than dMMR/MSI-H, leading to immune tolerance and evasion in the tumor microenvironment. Therefore, a number of investigative studies aimed at overcoming tumor resistance in current immunotherapy approaches are underway. A better understanding on the complexity and diversity of the immune system's functioning within the tumor microenvironment will increase the potential for developing predictive biomarkers and novel therapeutic strategies to potentiate anti-tumor immunity in patients with mCRC. In this review, we summarize the most recent advances in immunotherapy based on the findings of pivotal clinical trials for patients with mCRC, highlighting potent therapeutic approaches and predictive biomarkers.

Expression of PD-L1 and PD-L2 in colorectal cancer (CRC): A post-hoc integrated analysis of SCRUM-Japan GI-SCREEN CRC

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Background: PD-1, PD-L1/L2 axis is responsible for cancer immune escape which facilitate disease progression. However, expression of these proteins in CRC and its significance in clinical prognosis are yet to be fully clarified. Methods: This was a post-hoc analysis using FFPE tumor samples from the Nationwide Cancer Genome Screening Project, SCRUM-Japan GI-SCREEN for metastatic CRC. Patients (Pts) with MSI-H or BRAF V600E mutant tumors were prioritized to be included. PD-L1 (22C3) and PD-L2 expressions were centrally assessed using immunohistochemical assays at QualTek and NeoGenomics, respectively. Tumor infiltrating lymphocytes (TILs) were morphologically evaluated by H&E staining. Clinical information including biomarker status and overall survival (OS) were extracted from SCRUM-Japan GI-SCREEN database. Results: In total, 200 pts were included in this study with a median age of 65 (range, 29–88) years; male/female (116/84); MSI status MSI-H/non-MSI-H/unknown (8/189/3); RAS wild-type/mutant (113/87); and BRAF V600E wild-type/mutant (173/27). Positivity rate of PD-L1 in tumor cells (TC), immune cells (IC), PD-L2 on TC and IC were 10.8%, 46.9%, 0% and 20.3%, respectively. Expression of PD-L1 on TC or IC and PD-L2 on IC were associated with TIL (p = 0.023, p = 0.009, respectively). PD-L1 on TC was highly seen in BRAF V600E-mutated tumors (p = 0.043), but not related to other factors including RAS and MSI status. The pts with PD-L1+ tumors on TC or IC had longer OS than those with PD-L1- (Median, 31.9 vs 23.5 months; HR = 0.67, 95% CI, 0.46–0.99; p = 0.040), while OS in pts with PD-L2+ tumors was similar to that with PD-L2- (Median, 21.4 vs 27.3 months; HR = 0.87, 95% CI, 0.53–1.44; p = 0.60). The PD-L1 expression was also associated with the longer OS in pts with BRAF wild-type or non-MSI-H tumors. Conclusions: Our study suggested different prognostic impact of PD-L1 and PD-L2 expression in CRC pts, which require further evaluations as potential therapeutic targets for CRC. Clinical trial information: UMIN000016343.

Neutropenia and survival outcomes in metastatic colorectal cancer patients treated with trifluridine/tipiracil in the RECOURSE and J003 trials

Background:

The phase II J003 (N = 169) and phase III RECOURSE (N = 800) trials demonstrated a significant improvement in survival with trifluridine (FTD)/tipiracil (TPI) versus placebo in patients with refractory metastatic colorectal cancer. This post hoc analysis investigated pharmacokinetic data of FTD/TPI exposure and pharmacodynamic markers, such as chemotherapy-induced neutropenia (CIN) and clinical outcomes.

Patients and methods:

A total of 210 patients from RECOURSE were enrolled in this substudy. A limited sampling approach was used, with three pharmacokinetic samples drawn on day 12 of cycle 1. Patients were categorized as being above or below the median area under the plasma concentration–time curve (AUC) for FTD and TPI. We conducted a post hoc analysis using the entire RECOURSE population to determine the correlations between CIN and clinical outcome. We then carried out a similar analysis on the J003 trial to validate the results.

Results:

In the RECOURSE subset, patients in the high FTD AUC group had a significantly increased CIN risk. Analyses of the entire population demonstrated that FTD/TPI-treated patients with CIN of any grade in cycles 1 and 2 had significantly longer median overall survival (OS) and progression-free survival (PFS) than patients who did not develop CIN and patients in the placebo group. Patients who required an FTD/TPI treatment delay had increased OS and PFS versus those in the placebo group and those who did not develop CIN. Similar results were obtained in the J003 cohort.

Conclusions:

In RECOURSE, patients with higher FTD drug exposure had an increased CIN risk. FTD/TPI-treated patients who developed CIN had improved OS and PFS versus those in the placebo group and those who did not develop CIN. Similar findings were reported in the J003 cohort, thus validating the RECOURSE results. The occurrence of CIN may be a useful predictor of treatment outcomes for FTD/TPI-treated patients.

ClinicalTrials.gov identifier:

NCT01607957 (RECOURSE).

Japan Pharmaceutical Information Center number:

JapicCTI-090880 (J003).

Early hypertension and neutropenia are predictors of treatment efficacy in metastatic colorectal cancer patients administered FOLFIRI and vascular endothelial growth factor inhibitors as second-line chemotherapy

BACKGROUND

Three vascular endothelial growth factor (VEGF) inhibitors, Bevacizumab (BEV), ramucirumab (RAM), and aflibercept (AFL), are widely used for metastatic colorectal cancer (mCRC) patients who are treated with second-line chemotherapy. The difference in outcome between the three drugs has not been evaluated. In contrast to epidermal growth factor receptor inhibitors, VEGF inhibitors have few candidate predictors of efficacy.

METHODS

Consecutive mCRC patients who were treated with second-line chemotherapy were retrospectively enrolled. Overall response rate (ORR), progression-free survival (PFS), overall survival (OS), and safety were assessed. Subgroup analyses of prognostic and predictive efficacy markers were performed.

RESULTS

A total of 119 (41.2%), 107 (37.0%), and 63 patients (21.8%) were treated with FOLFIRI +BEV, RAM, or AFL, respectively. ORR, PFS, and OS showed no significant differences between three groups. However, the frequency of grade 3 or 4 adverse events (AEs) in the FOLFIRI +AFL group was significantly higher than that in the other groups (p < 0.001). Patients with grade 3 or 4 AEs, especially hypertension and neutropenia within the first four cycles of treatment had significantly longer PFS and OS than those without AEs, irrespective of treatment with VEGF inhibitors (p < 0.001). PFS in patients without prior BEV exposure was also significantly longer than that in patients with prior BEV exposure (p = 0.003).

CONCLUSIONS

Chemotherapeutic efficacy did not differ between the groups. Grade 3 or 4 AEs within the first four cycles of treatment and prior BEV exposure may be an effective predictor of treatment efficacy in mCRC patients administered VEGF inhibitors as second-line chemotherapy.

BRAF Mutation in Colorectal Cancers: From Prognostic Marker to Targetable Mutation

Simple Summary

Colorectal cancer with a mutation in an oncogene BRAF has paid much attention, as it comprises a population with dismal prognosis since two decades ago. A series of research since then has successfully changed this malignancy to be treatable with specific treatment. Here we thoroughly overviewed the basic, translational and clinical studies on colorectal cancer with BRAF mutation from a physician’s viewpoint. Accumulating lines of evidence suggest that intervention of the trunk cellular growth signal transduction pathway, namely EGFR-RAS-RAF-MEK-ERK pathway, is a clue to controlling this disease. However, it is not so straightforward. Recent studies unveil the diverse and plastic nature of this signal transduction pathway. We will introduce our endeavor to conquer this condition, based on newly arriving datasets, and discuss how we could open the door to future development of CRC treatment.

Abstract

The Raf murine sarcoma viral oncogene homolog B (BRAF) mutation is detected in 8–12% of metastatic colorectal cancers (mCRCs) and is strongly correlated with poor prognosis. The recent success of the BEACON CRC study and the development of targeted therapy have led to the determination of BRAF-mutated mCRCs as an independent category. For nearly two decades, a growing body of evidence has established the significance of the BRAF mutation in the development of CRC. Herein, we overview both basic and clinical data relevant to BRAF-mutated CRC, mainly focusing on the development of treatment strategies. This review is organized into eight sections, including clinicopathological features, molecular features, prognosis, the predictive value of anti-epidermal growth factor receptor (EGFR) therapy, resistant mechanisms for BRAF-targeting treatment, the heterogeneity of the BRAF mutation, future perspectives, and conclusions. A characterization of the canonical mitogen-activated protein kinase (MAPK) pathway is essential for controlling this malignancy, and the optimal combination of multiple interventions for treatments remains a point of debate.

Managing a gastrointestinal oncology practice in Japan during the COVID-19 pandemic: single institutional experience in The Cancer Institute Hospital of Japanese Foundation for Cancer Research

Coronavirus disease 2019 (COVID-19) was declared to be a global pandemic by the World Health Organization on March 11, 2020. On April 7, 2020, a state of emergency was declared in Japan, as had been by other nations worldwide. This unprecedented crisis has profound implications for patients undergoing chemotherapy and for practicing healthcare professionals. Various reports have shown data indicating that cancer patients with COVID-19 have high morbidity and mortality rates. In order to reduce the use of medical resources to avoid the risk of COVID-19 infections in both cancer patients and health care providers, oncologists now have to draw the line for cancer treatments by maintaining their efficacy while avoiding severe adverse events. In this article, we outlined the decisions made regarding the practice of gastrointestinal oncology in our institution during the COVID pandemic.

Evaluation of the RAS signaling network in response to MEK inhibition using organoids derived from a familial adenomatous polyposis patient

RAS signaling is a promising target for colorectal cancer (CRC) therapy, and a variety of selective inhibitors have been developed. However, their use has often failed to demonstrate a significant benefit in CRC patients. Here, we used patient-derived organoids (PDOs) derived from a familial adenomatous polyposis (FAP) patient to analyze the response to chemotherapeutic agents targeting EGFR, BRAF and MEK. We found that PDOs carrying KRAS mutations were resistant to MEK inhibition, while those harboring the BRAF class 3 mutation were hypersensitive. We used a systematic approach to examine the phosphorylation of RAS effectors using reverse-phase protein array (RPPA) and found increased phosphorylation of MEK induced by binimetinib. A high basal level of ERK phosphorylation and its rebound activation after MEK inhibition were detected in KRAS-mutant PDOs. Notably, the phosphorylation of EGFR and AKT was more closely correlated with that of MEK than that of ERK. Transcriptome analysis identified MYC-mediated transcription and IFN signaling as significantly correlated gene sets in MEK inhibition. Our experiments demonstrated that RPPA analysis of PDOs, in combination with the genome and transcriptome, is a useful preclinical research platform to understand RAS signaling and provides clues for the development of chemotherapeutic strategies.

Abstract 3877: A unique layered 3D stromal tissue model for in vitro evaluation of immunologic agents and immune cell infiltration into microenviroment

Background

The modulation of the immune system is a proven key target for cancer therapy, however, the complex interplay between immune cells and cancer cells in cancer microenvironment remains only partially understood. In addition, the currently available in vitro cancer microenvironment models are not designed to study the immunologic agents and a role of immune cells. Here, we developed a unique layered 3D stromal tissue model comprising immune, stromal and cancer cells.

Method

Layered 3D stromal tissue model was constructed by culturing fibroblasts and endothelial cells coated with extracellular matrix (ECM) and natural polysaccharide. Morphological analysis of the layered 3D stromal tissues and co-cultured tumor were evaluated by HE stain, immunohistochemistry and immunofluorescence (IF). For cytotoxicity assay, cancer cell lines were seeded on or in the 3D stromal tissue and incubated with peripheral blood mononuclear cell (PBMC) and Programmed cell death 1 (PD-1) blockade with Nivolumab. Remaining cancer cells post drug treatment were quantified by IF and imaging analysis.

Result

The co-cultured stromal tissues were multi-layered (approximately 20 layers), had microvascular formation. Hepatocyte growth factor (HGF) and vascular endothelial growth factor (VEGF) derived from fibroblast cells played important roles in tube formation. Moreover, the position of cancer cells in 3D stromal tissue was manipulated easily. PBMC infiltration into 3D stromal tissue and the interaction between PBMC and cancer cells were visualized. High level of programmed cell death ligand 1 (PD-L1) expression on cancer cells correlated with a higher response to PD-1 blockade in vitro as well as clinical trials.

Conclusion

We present a unique layered 3D cell culture system based on stromal/cancer/immune cells to study immunologic agents and immune cell infiltration in cancer microenvironment.

Our 3D model has the ability to reflect in vivo conditions closer than 2D model and provide a tool for in vitro tumor infiltrating lymphocyte (TIL) or immunologic agent testing.

Citation Format: Rii Morimura, Isana Nada, Kei Tsukamoto, Eiji Shinozaki, shiro kitano. A unique layered 3D stromal tissue model for in vitro evaluation of immunologic agents and immune cell infiltration into microenviroment [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3877.

Abstract 322: A unique ex vivo tumor model: 3D co-cultured system with cancer cells and stromal tissue for drug evaluation

Background;Recently, three-dimensional culture model has been reported as better tumor model than 2D culture. The importance of interaction between cancer and stromal cells has been widely recognized in tumor progression and resistance against treatment. So that ex vivo model which recaptures the tumor microenvironment is required to perform drug evaluation mimicking the patient tumor tissue.

Methods; Layered 3D stromal tissues with microvascular network were produced by culturing normal fibroblasts and endothelial cells coated with the extra-cellular matrix (ECM) and natural polysaccharide, namely collagen and heparin. The layered 3D stromal tissues and co-cultured tumor were morphologically evaluated by HE staining, immunohistochemistry and immunofluorescence (IF). Drug sensitivity assay were conducted using popular colorectal cancer cell lines, and patient-derived cell lines (PDCs) established in JFCR under approved IRB. Remaining cancer cells post drug treatment were quantified by IF and imaging analysis. Furthermore, in vivo drug sensitivity was also evaluated.

Results: The CD31 positive luminal structures which shows vascular endothelial tube formation were observed intra multi-layered tissues. The dense microvascular network tended to be formed nearby cancer cells. In comparison with 2D culture model, decreased drug sensitivities were represented in the layered 3D co-cultured model. The evaluated drug sensitivities in 3D model may reflect the response of cancer cells in in vivo.

Conclusion; We developed the layered 3D stromal tissue culture system including blood micro-vessels. Our unique 3D ex vivo model appear to be a valuable tool for drug evaluation, and thus further studies are underway to confirm the usefulness of our model. Testing approved and/or developing compounds with PDCs in the model would potentially enable better prediction their efficacy.

Citation Format: Yuki Takahashi, Kei Tsukamoto, Yuki Shimizu, Ryohei Katayama, Eiji Shinozaki, Satoshi Nagayama, Michiya Matsusaki, Shiro Kitano, Kensei Yamaguchi, Naoya Fujita. A unique ex vivo tumor model: 3D co-cultured system with cancer cells and stromal tissue for drug evaluation [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 322.