Biomarker-Guided Anti-Egfr Rechallenge Therapy in Metastatic Colorectal Cancer

Beneath the surface of Colorectal Cancer: unmasking the evolving nature of (Neo)RAS

Metastatic colorectal cancer (mCRC) remains a major clinical challenge, despite therapeutic advancements. Mutations in KRAS and NRAS (RAS) oncogenes drive resistance to anti-EGFR drugs, necessitating RAS mutational analysis prior to treatment. While tissue biopsy remains the gold standard for molecular profiling, it has limitations such as invasiveness, intra-tumoral heterogeneity, and delayed results. Liquid biopsy (LB), on the other hand, offers a non-invasive alternative by analyzing circulating tumor DNA (ctDNA) and it provides a dynamic view of molecular changes over time. Indeed, ctDNA analysis has expanded the understanding of the mCRC's molecular landscape, revealing that RAS mutated (MT) subclones undergo both a positive and a negative selection during treatment. This negative selection has been described as the "NeoRAS WT phenomenon." The temporary disappearance of RAS mutations opens "RAS WT windows," thus making potential candidates for anti-EGFR therapies even patients initially diagnosed as RAS MT. This review examines numerous studies investigating the clinical significance of the "NeoRas WT phenomenon" as a distinct pathological entity. It also highlights the key limitations arising from the variability in study designs, detecting methods and ctDNA shedding rates. The results of ongoing prospective trials are necessary to determine whether NeoRAS WT stands as a reliable marker for guiding anti-EGFR treatment strategies in RAS-mutated patients.

Rechallenge therapy versus tyrosine kinase inhibitor (TKI) for advanced metastatic colorectal cancer: a retrospective study

Currently, the standard third-line treatment options for advanced metastatic colorectal cancer (mCRC) include regorafenib, fruquintinib, and trifluridine/tipiracil (TAS-102), but these drugs have limited clinical efficacy. This study aims to evaluate the efficacy and survival outcomes of tyrosine kinase inhibitor (TKI) versus chemotherapy rechallenge in third-line treatment for advanced mCRC patients. From January 2019 to December 2022, 107 patients met the inclusion criteria. After 1:1 matching, there were 34 patients in both the TKI and rechallenge groups. Cox regression analysis was performed to identify independent predictive factors. The result indicated that Eastern Cooperative Oncology Group (ECOG) score of 0-1 (hazard ratio [HR] = 0.03, 95% confidence interval [CI]: 0.01-0.17; P < 0.001) and chemotherapy rechallenge (HR = 0.43, 95% CI: 0.23-0.79; P = 0.007) were independent protective factors for overall survival (OS). Patient-Generated Subjective Global Assessment (PG-SGA) score of 0-3 (HR = 0.43, 95% CI: 0.23-0.80; P = 0.008), progression-free survival (PFS) of frontline treatment (HR = 0.66, 95% CI: 0.43-1.00, P = 0.047) and chemotherapy rechallenge (HR = 0.42, 95% CI: 0.24-0.73; P = 0.002) were independent protective factors for PFS. Kaplan-Meier survival analysis showed that the median OS in the rechallenge group was 13.2 months (95% CI: 9.6-19.3), compared with 7.7 months (95% CI: 6.5-14.5) in the TKI group, with a statistically significant difference (HR = 0.47, 95% CI: 0.26-0.86; P = 0.013). The median PFS for the rechallenge group was 5.0 months (95% CI: 4.3-6.7), compared with 3.4 months (95% CI: 2.7-4.8) in the TKI group, with a statistically significant difference too (HR = 0.54, 95% CI: 0.32-0.91; P = 0.019). Furthermore, subgroup analysis showed that in Group A, the rechallenge group also had superior median OS and PFS compared with the TKI group. In conclusion, while TKIs are the current standard for third-line treatment in mCRC patients, chemotherapy rechallenge is a more effective option for patients who have achieved disease control in the first two lines of treatment.

Clinical outcomes of liposomal irinotecan in patients with advanced pancreatic cancer previously treated with conventional irinotecan: A meta-analysis of real-world evidence

BACKGROUND

Pivotal clinical trials supported survival benefits of liposomal irinotecan (nal-IRI) plus fluorouracil/leucovorin in patients with pancreatic ductal adenocarcinoma (PDAC) who previously received gemcitabine-based therapy. There are concerns about the benefits of nal-IRI in patients who received FOLFIRINOX (combined fluorouracil, leucovorin, IRI, and oxaliplatin) because of potential cross-resistance to IRI. The objective of this meta-analysis was to characterize the impact of the previous receipt of IRI on the outcomes of nal-IRI regimens in patients with advanced PDAC.

METHODS

Real-world studies evaluating the outcomes of nal-IRI in patients who had prior IRI exposure published up to April 2023 were searched using electronic databases. The meta-analysis was conducted using a random effects model to estimate pooled hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

Eight studies (n = 1368 patients) were included. The pooled median progression-free survival (PFS) was 2.02 months (95% CI, 1.43-2.57 months), and the median overall survival (OS) was 4.26 months (95% CI, 3.03-5.39 months). Patients with prior IRI exposure had PFS (HR, 1.17; 95% CI, 0.94-1.47; p = .17) and OS (HR, 1.16; 95% CI, 0.95-1.42; p = .16) comparable to patients without prior IRI exposure. Likewise, patients who had progressive disease on conventional IRI had PFS (HR, 1.50; 95% CI, 0.73-3.08; p = .24) and OS (HR, 1.70; 95% CI, 0.68-4.27; p = .26) with nal-IRI comparable to patients who had no progressive disease.

CONCLUSIONS

Prior IRI exposure does not affect the survival outcomes of nal-IRI regimens in patients who have advanced PDAC. The selection of later lines of chemotherapy regimens should be based on the differential safety profile, patient status, the cost of treatment, and health-related quality of life.

Rechallenge with Anti-EGFR Treatment in RAS/BRAF wt Metastatic Colorectal Cancer (mCRC) in Real Clinical Practice: Experience of the GITuD Group

BACKGROUND

There are few third- and fourth-line therapeutic options for metastatic colorectal cancer (mCRC). In RAS/BRAF wild-type (wt) mCRC previously treated with anti-epidermal growth factor receptor (anti-EGFR) (first-line) and relapsed after a good response, retreatment with anti-EGFR (rechallenge) emerges as a therapeutic alternative.

OBJECTIVE

The aim was to show the activity and safety of anti-EGFR rechallenge in RAS/BRAF wt mCRC in real-world practice.

PATIENTS AND METHODS

A multicenter, retrospective, observational study (six hospitals of the Galician Group of Research in Digestive Tumors) was conducted. Adult patients with RAS/BRAF wt mCRC, evaluated by liquid biopsy, were included. They received anti-EGFR rechallenge (cetuximab, panitumumab) as monotherapy, or combined with chemotherapy, in third- or subsequent lines. Efficacy (overall response rate [ORR], disease control rate [DCR], overall survival [OS], and progression-free survival [PFS]) and safety (incidence of adverse events [AEs]) were assessed.

RESULTS

Thirty-one patients were analyzed. Rechallenge (median 6 cycles [range 1-27], mainly cetuximab [80.7%]), started at a median anti-EGFR-free time of 18.4 months (1.7-37.5 months) after two (38.7%) or more (61.3%) lines of treatment; 64.5% of patients received a full dose. Median OS and PFS were 9.8 months (95% confidence interval [CI] 8.2-11.4) and 2.6 months (95% CI 1.7-3.4), respectively. ORR was 10%, and DCR was 30%. The most common AEs were diarrhea (35.5%), anemia (29%), emesis (6.4%), and neutropenia (6.4%); < 5% grade ≥ 3; 48.4% of patients reported anti-EGFR-related skin toxicity (grade > 1). Hypomagnesemia required supplements in 29% of patients. Dose delays (≥ 3 days) and reduction (≥ 20%) were reported in 11 (35.5%) and seven patients (22.6%), respectively.

CONCLUSIONS

In RAS/BRAF wt mCRC patients, an anti-EGFR rechallenge provides a feasible therapeutic option with clinical benefit (survival) and a manageable safety profile.

Anti-EGFR Rechallenge in Patients With Refractory ctDNA RAS/BRAF wt Metastatic Colorectal Cancer: A Nonrandomized Controlled Trial

Importance

The available evidence regarding anti-epidermal growth factor receptor (EGFR) inhibitor rechallenge in patients with refractory circulating tumor DNA (ctDNA) RAS/BRAF wild-type (wt) metastatic colorectal cancer (mCRC) is derived from small retrospective and prospective studies.

Objective

To evaluate the efficacy of anti-EGFR rechallenge in patients with refractory ctDNA RAS/BRAF wt mCRC.

Design, Setting, and Participants

This nonrandomized controlled trial used a pooled analysis of individual patient data from patients with RAS/BRAF wt ctDNA mCRC enrolled in 4 Italian trials (CAVE, VELO, CRICKET, and CHRONOS) and treated with anti-EGFR rechallenge between 2015 and 2022 (median [IQR] follow-up, 28.1 [25.8-35.0] months).

Intervention

Patients received anti-EGFR rechallenge therapy, including cetuximab plus avelumab, trifluridine-tipiracil plus panitumumab, irinotecan plus cetuximab, or panitumumab monotherapy.

Main Outcomes and Measures

Overall survival (OS), progression-free survival (PFS), overall response rate (ORR), and disease control rate (DCR) were calculated. Exploratory subgroup analysis evaluating several clinical variables was performed. Safety was reported.

Results

Overall, 114 patients with RAS/BRAF wt ctDNA mCRC (median [IQR] age, 61 [29-88] years; 66 men [57.9%]) who received anti-EGFR rechallenge as experimental therapy (48 received cetuximab plus avelumab, 26 received trifluridine-tipiracil plus panitumumab, 13 received irinotecan plus cetuximab, and 27 received panitumumab monotherapy) were included in the current analysis. Eighty-three patients (72.8%) had received 2 previous lines of therapy, and 31 patients (27.2%) had received 3 or more previous lines of therapy. The ORR was 17.5% (20 patients), and the DCR was 72.3% (82 patients). The median PFS was 4.0 months (95% CI, 3.2-4.7 months), and the median OS was 13.1 months (95% CI, 9.5-16.7 months). The subgroup of patients without liver involvement had better clinical outcomes. The median PFS was 5.7 months (95% CI, 4.8-6.7 months) in patients without liver metastasis compared with 3.6 months (95% CI, 3.3-3.9 months) in patients with liver metastasis (hazard ratio, 0.56; 95% CI, 0.37-0.83; P = .004). The median OS was 17.7 months (95% CI, 13-22.4 months) in patients without liver metastasis compared with 11.5 months (95% CI, 9.3-13.9 months) in patients with liver metastasis (hazard ratio, 0.63; 95% CI, 0.41-0.97; P = .04). Treatments showed manageable toxic effects.

Conclusions and Relevance

These findings suggest that anti-EGFR rechallenge therapy has promising antitumor activity in patients with refractory ctDNA RAS/BRAF wt mCRC. Within the limitation of a subgroup analysis, the absence of liver metastases was associated with significant improved survival.

Trial Registration

ClinicalTrials.gov Identifiers: NCT02296203; NCT04561336; NCT03227926; NCT05468892.

Chemotherapy re-use versus anti-angiogenic monotherapy as the third-line treatment of patients with metastatic colorectal cancer: a real-world cohort study

BACKGROUND

There are various recommendations for third-line treatment in mCRC, however, there is no consensus on who is more suitable for particular strategy. Chemotherapy re-use in third-line setting is a common option in clinical practice. This study aimed to investigate the efficacy of third-line chemotherapy re-use by the comparison with that of anti-angiogenic monotherapy, and further find the population more suitable for third-line chemotherapy.

METHODS

Using electronic medical records of patients with mCRC, a retrospective cohort study was conducted. A total of 143 patients receiving chemotherapy and 40 patients receiving anti-angiogenic monotherapy in third-line setting as control group were retrospectively collected. Baseline characteristics were analyzed using the χ² test or the Fisher's exact test. ROC curve and surv_cutpoint function of 'survminer' package in R software were used to calculate the cut-off value. Survival curves were plotted with the Kaplan-Meier method and were compared using the log-rank test. The Cox proportional hazard regression model was used to analyze the potential risk factors.

RESULTS

A total of 143 patients receiving chemotherapy and 40 patients receiving anti-angiogenic monotherapy in third-line setting were retrospectively collected. Chemotherapy rechallenge was recorded in 93 patients (93/143, 65.0%), and the remaining patients chose new chemotherapeutic drugs that had not been previously used, including irinotecan-based (22/50), oxaliplatin-based (9/50), raltitrexed (9/50), gemcitabine (5/50) and other agents (5/50). The ORR and DCR of third-line chemotherapy reached 8.8%, 61.3%, respectively (anti-angiogenic monotherapy group: ORR 2.6%, DCR 47.4%). The mPFS and mOS of patients receiving chemotherapy were 4.9 and 12.0 m, respectively (anti-angiogenic monotherapy group: mPFS 2.7 m, mOS 5.2 m). Subgroup analyses found that patients with RAS/RAF mutation, longer PFS (greater than 10.6 m) in front-line treatment or larger tumor burden had better prognosis with third-line chemotherapy rather than anti-angiogenic monotherapy.

CONCLUSIONS

Third-line chemotherapy re-use was effective in mCRC. Those with more aggressive characteristics (RAS/RAF mutant, larger tumor burden) or better efficacy of previous chemotherapy (longer PFS) were more appropriate for third-line chemotherapy, rather than anti-angiogenic monotherapy.

Efficacy, safety and genomic analysis of SCT200, an anti-EGFR monoclonal antibody, in patients with fluorouracil, irinotecan and oxaliplatin refractory RAS and BRAF wild-type metastatic colorectal cancer: a phase Ⅱ study

BACKGROUND

Limited therapeutic options are available for metastatic colorectal cancer (mCRC) patients after failure of first- and second-line therapies, representing an unmet medical need for novel therapies.

METHODS

This is an open-label, single arm, multicenter, phase Ⅱ study aiming to perform the efficacy, safety and genomic analysis of SCT200, a noval fully humanized IgG1 anti-epidermal growth factor receptor (EGFR) monoclonal antibody, in patients with fluorouracil, irinotecan and oxaliplatin refractory RAS and BRAF wild-type mCRC. SCT200 (6 mg/kg) was given weekly for the first six weeks, followed by a higher dose of 8 mg/kg every two weeks until disease progression or unacceptable toxicity. Primary endpoint was independent review committee (IRC)-assessed objective response rate (ORR) and secondary endpoints included ORR in patients with left-sided tumor, disease control rate (DCR), duration of response (DoR), time to response (TTR), progression-free survival (PFS), overall survival (OS) and safety.

FINDINGS

From February 12, 2018 to December 1, 2019, a total of 110 patients aged between 26 and 77 years (median: 55; interquartile range [IQR]: 47-63) with fluorouracil, oxaliplatin, and irinotecan refractory RAS and BRAF wild-type mCRC were enrolled from 22 hospitals in China. As the data cut-off date on May 15, 2020, the IRC-assessed ORR and DCR was 31% (34/110, 95% confidence interval [CI] 22-40%) and 75% (82/110, 95% CI 65-82%), respectively. Thirty one percent (34/110) patients achieved confirmed partial response (PR). The median PFS and median OS were 5.1 months (95% CI 3.4-5.2) and 16.2 months (95% CI 11.1-not available [NA]), respectively. The most common ≥ grade 3 treatment-related adverse events (TRAEs) were hypomagnesemia (17%, 19/110) and acneiform dermatitis (11%, 12/110). No deaths occurred. Genomic analysis suggested positive association between MYC amplification and patients' response (P = 0.0058). RAS/RAF mutation and MET amplification were the most frequently detected resistance mechanisms. Patients with high circulating tumor DNA (ctDNA) at baseline or without ctDNA clearance at the 7th week after the first dose of SCT200 administration before receiving SCT200 had worse PFS and OS.

INTERPRETATION

SCT200 exhibited promising clinical efficacy and manageable safety profiles in RAS and BRAF wild-type mCRC patients progressed on fluorouracil, irinotecan and oxaliplatin treatment. The baseline ctDNA and ctDNA clearance status at the 7th week after the first dose of SCT200 administration before receiving SCT200 could be a potential prognostic biomarker for RAS and BRAF wild-type mCRC patients with SCT200 therapy.

FUNDING

This study was sponsored by Sinocelltech Ltd., Beijing, China and partly supported by the National Science and Technology Major Project for Key New Drug Development (2019ZX09732001-006, 2017ZX09304015).

Anti-EGFR Antibodies in the Management of Advanced Colorectal Cancer

Colorectal cancer is the third most common cancer worldwide, and incidence is rising in younger individuals. Anti-EGFR antibodies, including cetuximab and panitumumab, have been incorporated into standard-of-care practice for patients with advanced disease. Herein, we review the molecular characteristics of these agents and the trials that lead to their approvals. Further, we discuss clinical implications of data regarding biomarkers that dictate treatment selection, different dosing strategies, and side effect management. Finally, we look towards the future and describe contexts in which these agents are currently being investigated clinically with a focus on combinations with MAPK-targeted therapies and immunotherapy. Overall, this review provides historical context, current clinical usage, and future directions for anti-EGFR antibodies in advanced colorectal cancer.

Panitumumab plus trifluridine/tipiracil as anti-EGFR rechallenge therapy in patients with refractory RAS wild-type metastatic colorectal cancer: Overall survival and subgroup analysis of the randomized phase II VELO trial

The randomized phase II VELO trial showed that the addition of panitumumab to trifluridine/tipiracil significantly improves progression-free survival (PFS) as compared to trifluridine/tipiracil in third-line therapy in patients with refractory RAS wild-type (WT) metastatic colorectal cancer (mCRC). With longer follow-up, final overall survival results and posttreatment subgroup analysis are presented. Sixty-two patients with refractory RAS WT mCRC were randomly assigned to receive, as third-line therapy, trifluridine/tipiracil alone (arm A) or in combination with panitumumab (arm B). Primary endpoint was PFS; secondary endpoints included overall survival (OS) and overall response rate (ORR). Median OS was 13.1 months (95% CI 9.5-16.7) in arm A compared to 11.6 months (95% CI 6.3-17.0) in arm B (HR: 0.96, 95% CI 0.54-1.71, P = .9). To evaluate the impact of subsequent lines of treatment, subgroup analysis was performed for the 24/30 patients in arm A, that received fourth-line therapy after disease progression. Median PFS was 4.1 months (95% CI 1.44-6.83) for 17 patients treated with anti-EGFR rechallenge as compared to 3.0 months (95% CI 1.61-4.31) for seven patients that received other therapies (HR: 0.29, 95% CI 0.10-0.85, P = .024). Median OS from the start of fourth-line treatment was 13.6 months (95% CI 7.2-20), and 5.1 months (95% CI 1.8-8.3) for patients treated with anti-EGFR rechallenge vs other therapies, respectively (HR: 0.30, 95% CI 0.11-0.81, P = .019). Final results of the VELO trial support the role of anti-EGFR rechallenge in the continuum of care of patients with RAS/BRAF WT mCRC.

Panitumumab Plus Trifluridine-Tipiracil as Anti-Epidermal Growth Factor Receptor Rechallenge Therapy for Refractory RAS Wild-Type Metastatic Colorectal Cancer: A Phase 2 Randomized Clinical Trial

Importance

Current third-line therapies for patients with metastatic colorectal cancer (MCRC) have limited efficacy. Rechallenge with epidermal growth factor receptor (EGFR) inhibitors for RAS wild-type (WT) MCRC may be valuable for these patients.

Objective

To compare the anti-EGFR monoclonal antibody panitumumab plus standard-of-care trifluridine-tipiracil with trifluridine-tipiracil alone as third-line therapy for RAS WT MCRC.

Design, Setting, and Participants

This phase 2 randomized clinical trial (RCT) was conducted in 7 Italian centers from June 2019 to April 2022. Patients with refractory RAS WT MCRC who had a partial or complete response to first-line chemotherapy plus an anti-EGFR monoclonal antibody and an anti-EGFR drug-free interval of 4 or more months during second-line therapy were included.

Interventions

Patients were randomized 1:1 to receive panitumumab plus trifluridine-tipiracil or trifluridine-tipiracil alone.

Main Outcomes and Measures

The primary end point was progression-free survival (PFS). Circulating tumor DNA (ctDNA) extended sequence variation analysis was performed in a subgroup of patients.

Results

Of 62 included patients, 31 received panitumumab plus trifluridine-tipiracil (19 [61.3%] male; median age, 65 years [range, 39-81 years]) and 31 received trifluridine-tipiracil alone (17 [54.8%] male; median age, 66 years [range, 32-82 years]). The primary end point was met. Median PFS was 4.0 months (95% CI, 2.8-5.3 months) in the panitumumab plus trifluridine-tipiracil arm vs 2.5 months (95% CI, 1.4-3.6 months) in the trifluridine-tipiracil only (hazard ratio [HR], 0.48; 95% CI, 0.28-0.82; P = .007). Pretreatment plasma RAS/BRAF WT ctDNA identified patients obtaining prolonged clinical benefit with panitumumab plus trifluridine-tipiracil compared with trifluridine-tipiracil, with PFS rates at 6 months of 38.5% vs 13.0% and at 12 months of 15.4% vs 0%. A ctDNA liquid-biopsy extended mutation analysis by FoundationOne Liquid CDx (profiling 324 genes) was performed in a subgroup of patients with baseline plasma RAS/BRAF WT ctDNA; in 15 of 23 patients (65.2%) whose tumors were WT for KRAS, NRAS, BRAFV600E, EGFR, ERBB2, MAP2K1, and PIK3CA, median PFS was 6.4 months (95% CI, 3.7-9.2 months). Within this group of 15 patients, 2 (13.3%) had partial response, 11 (73.3%) had stable disease, and 2 (13.3%) had disease progression as best response.

Conclusions and Relevance

In this RCT, third-line treatment with the anti-EGFR monoclonal antibody panitumumab plus the standard-of-care trifluridine-tipiracil resulted in improved PFS compared with treatment with trifluridine-tipiracil alone among patients with refractory RAS WT MCRC. The findings support the clinical utility of liquid biopsy-guided anti-EGFR rechallenge therapy for refractory RAS WT MCRC.

Trial Registration

ClinicalTrials.gov Identifier: NCT05468892.

Mechanisms of esophageal cancer metastasis and treatment progress

Esophageal cancer is a prevalent tumor of the digestive tract worldwide. The detection rate of early-stage esophageal cancer is very low, and most patients are diagnosed with metastasis. Metastasis of esophageal cancer mainly includes direct diffusion metastasis, hematogenous metastasis, and lymphatic metastasis. This article reviews the metabolic process of esophageal cancer metastasis and the mechanisms by which M2 macrophages, CAF, regulatory T cells, and their released cytokines, including chemokines, interleukins, and growth factors, form an immune barrier to the anti-tumor immune response mediated by CD8+ T cells, impeding their ability to kill tumor cells during tumor immune escape. The effect of Ferroptosis on the metastasis of esophageal cancer is briefly mentioned. Moreover, the paper also summarizes common drugs and research directions in chemotherapy, immunotherapy, and targeted therapy for advanced metastatic esophageal cancer. This review aims to serve as a foundation for further investigations into the mechanism and management of esophageal cancer metastasis.

Pretreatment Plasma Circulating Tumor DNA RAS/BRAF Mutational Status in Refractory Metastatic Colorectal Cancer Patients Who Are Candidates for Anti-EGFR Rechallenge Therapy: A Pooled Analysis of the CAVE and VELO Clinical Trials

Rechallenge with anti-EGFR drugs represents a promising strategy in refractory RAS/BRAF wild-type (WT) metastatic colorectal cancer (mCRC). We performed the pooled analysis of the CAVE and VELO studies to evaluate the percentage of patients with WT circulating tumor DNA (ctDNA) tumors and the association of mutational status with time from the last anti-EGFR drug administration. At baseline, 97/129 patients had RAS/BRAF WT plasma ctDNA, while 32/129 had RAS/BRAF mutated plasma ctDNA. Median anti-EGFR drug-free interval was 10.6 (CI 95%, 8.9-13.4) months in the plasma RAS/BRAF mutant group as compared to 13.0 (CI 95%, 11.1-16.6) months in RAS/BRAF WT group (p = 0.169). To investigate the time window of the RAS/BRAF mutant cancer cell clone disappearance, descriptive analysis using different time points was performed. No difference in the proportion of patients whose baseline plasma ctDNA was RAS/BRAF WT or mutated was found between 4 and 18 months since the last administration of anti-EGFR drugs. In contrast, 38/44 of patients with anti-EGFR drug-free interval of 18 months or more displayed a ctDNA RAS/BRAF WT status. Taken together, these results shows that the length of anti-EGFR free interval is not a sufficient criterion for patient selection, supporting the role of liquid biopsies for improving treatment efficacy.

Trifluridine/tipiracil (FTD/TPI) and regorafenib in older patients with metastatic colorectal cancer

Colorectal cancer is a disease of older patients, but few guidelines directly address age in their recommendations. Older patients may present comorbidities that affect the choice of chemotherapy, and care must be taken when choosing the best approach. This narrative review aimed to describe the literature regarding approved oral agents for third-line treatment in older patients with refractory metastatic colorectal cancer, regorafenib, and trifluridine/tipiracil (FTD/TPI).

Circulating Tumor DNA: The Dawn of a New Era in the Optimization of Chemotherapeutic Strategies for Metastatic Colo-Rectal Cancer Focusing on RAS Mutation

Genotyping of tumor tissues to assess RAS and BRAF V600E mutations enables us to select optimal molecularly targeted therapies when considering treatment strategies for patients with metastatic colorectal cancer. Tissue-based genetic testing is limited by the difficulty of performing repeated tests, due to the invasive nature of tissue biopsy, and by tumor heterogeneity, which can limit the usefulness of the information it yields. Liquid biopsy, represented by circulating tumor DNA (ctDNA), has attracted attention as a novel method for detecting genetic alterations. Liquid biopsies are more convenient and much less invasive than tissue biopsies and are useful for obtaining comprehensive genomic information on primary and metastatic tumors. Assessing ctDNA can help track genomic evolution and the status of alterations in genes such as RAS, which are sometimes altered following chemotherapy. In this review, we discuss the potential clinical applications of ctDNA, summarize clinical trials focusing on RAS, and present the future prospects of ctDNA analysis that could change daily clinical practice.

Rechallenge with anti-EGFR therapy to extend the continuum of care in patients with metastatic colorectal cancer

In patients with RAS wild-type metastatic colorectal cancer (mCRC), an anti-epidermal growth factor receptor (EGFR) monoclonal antibody plus chemotherapy is a standard option for treatment in the first-line setting. Patients who progress while on treatment with anti-EGFR-based therapy can be resistant to further anti-EGFR treatment, but evidence suggests that the anti-EGFR-resistant clones decay, thereby opening the potential for rechallenge or reintroduction in later lines of treatment. Results from recent clinical studies have shown that some patients with mCRC who are rechallenged with anti-EGFR monoclonal antibodies exhibit durable responses. While other therapies have demonstrated improved overall survival in chemorefractory mCRC over the past decade, rechallenge with anti-EGFR monoclonal antibodies in later lines of treatment represents a new option that deserves further investigation in clinical trials. In this review, we summarize the molecular rationale for rechallenge or reintroduction in patients with mCRC who have progressed on earlier-line anti-EGFR treatment and examine the current evidence for using liquid biopsy as a method for selecting rechallenge as a therapeutic option. We also provide an overview of published trials and trials in progress in this field, and outline the potential role of rechallenge in the current clinical setting.

Silencing of RhoC induces macrophage M1 polarization to inhibit migration and invasion in colon cancer via regulating the PTEN/FOXO1 pathway

Ras homologue family member C (RhoC) is an oncogene in diverse types of human cancers, whereas its regulatory mechanisms involving macrophage polarization is rarely investigated. This study is designed to explore the regulatory role of RhoC in colon cancer and the underlying molecular mechanisms involving macrophage polarization. We detected RhoC expression by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot, and analysed the biological function of RhoC knockdown in CC cells by the MTT, wound healing and transwell assay. Macrophage polarization-associated markers, genes associated with migration, phosphatase and tensin homologue (PTEN) and forkhead box O (FOXO) were determined by qRT-PCR and western blot. The xenograft tumour mouse model was used to assess the role of RhoC in vivo. RhoC is highly expressed in CC cells. The cell viability, invasion and migration abilities of CC cells were reduced by knockdown of RhoC. RhoC knockdown promoted M1 polarization, inhibited M2 polarization and decreased levels of genes associated with migration (matrix metalloproteinase-2 and matrix metalloproteinase-9). Silencing of RhoC inhibited tumour growth and expression of genes associated with migration in the xenografted model. In addition, silencing of RhoC promoted PTEN/FOXO1 expression, and PTEN inhibitor (SF1670) reversed the inhibitory effects of RhoC silencing. We demonstrated that silencing of RhoC reduced CC cells invasion and migration, and tumour growth by suppressing M2 macrophage polarization via regulating the PTEN/FOXO1 pathway.

Liquid biopsy to detect resistance mutations against anti-epidermal growth factor receptor therapy in metastatic colorectal cancer

Colorectal cancer (CRC) is a major cause of mortality worldwide, associated with a steadily growing prevalence. Notably, the identification of KRAS, NRAS, and BRAF mutations has markedly improved targeted CRC therapy by affording treatments directed against the epidermal growth factor receptor (EGFR) and other anti-angiogenic therapies. However, the survival benefit conferred by these therapies remains variable and difficult to predict, owing to the high level of molecular heterogeneity among patients with CRC. Although classification into consensus molecular subtypes could optimize response prediction to targeted therapies, the acquisition of resistance mutations to targeted therapy is, in part, responsible for the lack of response in some patients. However, the acquisition of such mutations can induce challenges in clinical practice. The utility of liquid biopsy to detect resistance mutations against anti-EGFR therapy has recently been described. This approach may constitute a new standard in the decision algorithm for targeted CRC therapy.

Circulating Tumor DNA in Identifying Resistant Sub-Clones Post EGFR Blockade: Implications for EGFR Rechallenge

For patients with metastatic RAS/RAF wild-type refractory colorectal cancer, the question of anti-EGFR therapy rechallenge often comes up after initial use. However, not all patients derive benefit. It is now well known that these tumors acquire mechanisms of resistance in the mitogen-activated protein kinase (MAPK) pathway, which can be detected on circulating tumor DNA (ctDNA)-based testing. We present a series of patients who had serial testing post-EGFR blockade showing its feasibility and value. This would have implications for EGFR rechallenge. We reviewed records for patients who were initially noted to be RAS/RAF wild-type on tissue, who received prior anti-EGFR therapy and then subsequently had at least one circulating tumor DNA-based testing. These patients also had tissue-based genomic testing obtained earlier as part of their standard of care, alongside serial ctDNA-based testing that was done later when subsequent lines of therapy were being decided. The median duration of initial prior anti-EGFR therapy was around 10 months. Known acquired mechanisms of resistance were noted in 100% of the cases. These included KRAS, NRAS, extracellular domain mutations in EGFR, and BRAF mutations. Interestingly, the levels of the sub-clones expressed in variant allele fraction percentage varied and decreased over time in relation to timing of the prior EGFR exposure. Additionally, these were noted to be polyclonal, and the number of clones also varied including some disappearing over time during non-EGFR-based therapy (EGFR holiday). Patients’ post-EGFR blockade may have multiple mechanisms of acquired resistance that can be easily detected on non-invasive liquid biopsies. These patients do not benefit from EGFR rechallenge based on the results of the recently reported CRICKET (NCT02296203) and CAVE (NCT04561336) clinical trials. Furthermore, excluding these patients from EGFR rechallenge is already being adopted in prospectively done clinical trials, e.g., the CHRONOS study (NCT03227926). Rechecking the liquid biopsy plasma RAS/RAF status is one thing that may be incorporated into practice with EGFR rechallenge only a consideration if acquired mechanisms of resistance are absent.

Post-Induction Management in Patients With Left-Sided RAS and BRAF Wild-Type Metastatic Colorectal Cancer Treated With First-Line Anti-EGFR-Based Doublet Regimens: A Multicentre Study

Background

Few data regarding post-induction management following first-line anti-epidermal growth factor receptor (EGFR)-based doublet regimens in patients with left-sided RAS/BRAF wild-type metastatic colorectal cancer (mCRC) are available.

Methods

This multicenter, retrospective study aimed at evaluating clinicians’ attitude, and the safety and effectiveness of post-induction strategies in consecutive patients affected by left-sided RAS/BRAF wild-type mCRC treated with doublet chemotherapy plus anti-EGFR as first-line regimen, who did not experience disease progression within 6 months from induction initiation, at 21 Italian and 1 Spanish Institutions. The measured clinical outcomes were: progression-free survival (PFS), overall survival (OS), adverse events, and objective response rate (ORR).

Results

At the data cutoff, among 686 consecutive patients with left-sided RAS/BRAF wild-type mCRC treated with doublet plus anti-EGFR as first-line regimen from March 2012 to October 2020, 355 eligible patients have been included in the present analysis. Among these, 118 (33.2%), 66 (18.6%), and 11 (3.1%) received a maintenance with 5-fluorouracil/leucovorin (5FU/LV)+anti-EGFR, anti-EGFR, and 5FU/LV, respectively, while 160 (45.1%) patients continued induction treatment (non-maintenance) until disease progression, unacceptable toxicity, patient decision, or completion of planned treatment. The median period of follow-up for the overall population was 33.7 months (95%CI = 28.9–35.6). The median PFS values of the 5FU/LV+anti-EGFR, anti-EGFR, 5FU/LV, and non-maintenance cohorts were 16.0 (95%CI = 14.3–17.7, 86 events), 13.0 (95%CI = 11.4–14.5, 56 events), 14.0 (95%CI = 8.1–20.0, 8 events), and 10.1 months (95%CI = 9.0–11.2, 136 events), respectively (p < 0.001). The median OS values were 39.6 (95%CI = 31.5–47.7, 43 events), 36.1 (95%CI = 31.6–40.7, 36 events), 39.5 (95%CI = 28.2–50.8, 4 events), and 25.1 months (95%CI = 22.6–27.6, 99 events), respectively (p < 0.001). After adjusting for key covariates, a statistically significant improvement in PFS in favor of 5FU/LV+anti-EGFR (HR = 0.59, 95%CI = 0.44–0.77, p < 0.001) and anti-EGFR (HR = 0.71, 95%CI = 0.51–0.98, p = 0.039) compared to the non-maintenance cohort was found. Compared to the non-maintenance cohort, OS was improved by 5FU/LV+anti-EGFR (HR = 0.55, 95%CI = 0.38–0.81, p = 0.002) and, with marginal significance, by anti-EGFR (HR = 0.67, 95%CI = 0.51–0.98, p = 0.051). No difference was found in ORR. Any grade non-hematological and hematological events were generally higher in the non-maintenance compared to the maintenance cohorts.

Conclusion

Among the treatment strategies following an anti-EGFR-based doublet first-line induction regimen in patients affected by left-sided RAS/BRAF wild-type mCRC treated in a “real-life” setting, 5FU/LV+anti-EGFR resulted the most adopted, effective, and relatively safe regimen.

Skin Toxicity as Predictor of Survival in Refractory Patients with RAS Wild-Type Metastatic Colorectal Cancer Treated with Cetuximab and Avelumab (CAVE) as Rechallenge Strategy

The single-arm phase II CAVE mCRC trial evaluated the combination of cetuximab plus avelumab as rechallenge strategy in RAS wild-type (WT) metastatic colorectal cancer (mCRC) patients, with clinical response to first-line anti-EGFR-based chemotherapy, who progressed and received a subsequent line of therapy. The correlation of skin toxicity (ST) and different clinico-molecular variables with overall survival (OS), progression-free survival (PFS) and response rate (RR) was assessed at univariate and multivariate analysis. A total of 33/77 (42.9%) patients experienced grade 2-3 ST and displayed median OS (mOS) of 17.8 months (CI 95%, 14.9-20.6); whereas 44/77 (57.1%) patients with grade 0-1 ST exhibited mOS of 8.2 months (CI 95%, 5.5-10.9), (hazard ratio (HR), 0.51; CI 95%, 0.29-0.89; p = 0.019). Median PFS (mPFS) was 4.6 months (CI 95%, 3.4-5.7) in patients with grade 2-3 ST, compared to patients with grade 0-1 ST with mPFS of 3.4 months (CI 95%, 2.7-4.1; HR, 0.49; CI 95%, 0.3-0.8; p = 0.004). Grade 2-3 ST (HR, 0.51; CI 95%, 0.29-0.89; p = 0.019) and RAS/BRAF/EGFR WT circulating tumor DNA (ctDNA) (HR, 0.50; CI 95%, 0.27-0.9; p = 0.019) had a statistically significant effect on OS at univariate analysis. At the multivariate analysis, RAS/BRAF/EGFR WT ctDNA status maintained statistical significance (HR, 0.49; CI 95%, 0.27-0.9; p = 0.023), whereas there was a trend towards ST grade 2-3 (HR, 0.54; CI 95%, 0.29-1.01; p = 0.054). Skin toxicity is a promising biomarker to identify patients with mCRC that could benefit of anti-EGFR rechallenge.

Pharmacotherapy for unresectable metastatic colorectal cancer

INTRODUCTION

Unresectable metastatic colorectal cancer (mCRC) has a poor prognosis. Emerging treatment paradigms have improved outcomes in selected unresectable mCRC cases. Recent therapeutic advancements are due in part to a shift in trial designs. By examining CRC as a heterogeneous group of various tumor subtypes, researchers have identified molecular distinctions that have led to promising targets.

AREAS COVERED

Nineteen antineoplastic agents are included in the National Comprehensive Cancer Network guidelines for the palliative management of mCRC. However, not all patients will be candidates for each agent. New therapies for rare mCRC subtypes have emerged. Herein, the authors review these rare mCRC subtypes: microsatellite instability-high/deficient mismatch repair, BRAFV600E-mutant, and human epidermal growth factor receptor 2-positive tumors. Additionally, they provide an overview of unresectable mCRC management and future directions.

EXPERT OPINION

Treatment in the majority of mCRC patients (RAS wild-type or RAS-mutant, microsatellite instability-stable or -low/mismatch repair-proficient, BRAFV600E wild-type, or HER2-negative) needs further advancement and remains an unmet need. The authors believe that the key to identifying more breakthroughs in these mCRC patients is to continue to differentiate their tumors molecularly and clinically.