Optimising the use of cetuximab in the continuum of care for patients with metastatic colorectal cancer

Loss of RAS Mutations in Liquid Biopsies of Patients With Multi-Treated Metastatic Colorectal Cancer

BACKGROUND

Liquid biopsy (LB) is a non-invasive tool to evaluate the heterogeneity of tumors. Since RAS mutations (RAS-mut) play a major role in resistance to antiepidermal growth factor receptor inhibitors (EGFR) monoclonal antibodies (Mabs), serial monitoring of RAS-mut with LB may be useful to guide treatment. The main aim of this study was to evaluate the prognostic value of the loss of RAS-mut (NeoRAS-wt) in LB, during the treatment of metastatic colorectal cancer (mCRC).

METHODS

A retrospective study was conducted on patients with mCRC between January 2018 and December 2021. RAS-mut were examined in tissue biopsy, at mCRC diagnosis, and with LB, during treatment.

RESULTS

Thirty-nine patients with RAS-mut mCRC were studied. LB was performed after a median of 3 lines (0-7) of systemic treatment including anti-vascular endothelial growth factor (anti-VEGF) Mabs. NeoRAS-wt was detected in 13 patients (33.3%); 9 (69.2%) of them received further treatment with anti-EGFR Mabs with a disease control rate of 44.4%. Median overall survival (OS), from the date of LB testing, was 20 months in the NeoRAS-wt group and 9 months in the persistent RAS-mut group (log-rank 2.985; P = .08), with a 12-month OS of 84.6% and 57.7%, respectively. NeoRAS-wt was identified as a predictor of survival (HR = 0.29; P = .007), with an 11-month improvement in median OS and a 71% decrease in risk of death, in heavily pretreated patients.

CONCLUSIONS

In conclusion, monitoring clonal evolution in mCRC by LB may provide an additional treatment line for patients with NeoRAS-wt in advanced disease.

Emerging role of liquid biopsy in rat sarcoma virus mutated metastatic colorectal cancer: A case report

BACKGROUND

In patients with metastatic colorectal cancer (mCRC), the treatment options are limited and have been proved to be affected by rat sarcoma virus (RAS) mutational status. In RAS wild-type (wt) patients, the combination of anti-epidermal growth factor receptor (EGFR) monoclonal antibodies with chemotherapy (CT) is more effective than CT alone. On the other hand, RAS-mutated patients are not eligible for treatment with anti-EGFR antibodies.

CASE SUMMARY

Eleven patients with initially RAS-mutated mCRC were followed from diagnosis to May 2022. At the time of cell-free DNA determination, five patients had undergone one CT line, five patients had undergone two CT lines, and one patient had undergone three CT lines (all in combination with bevacizumab). At the second and third treatment lines [second line (2L), third line (3L)], patients with neo-RAS wt received a combination of CT and cetuximab. In neo-RAS wt patients treated with anti-EGFR, our findings indicated an increase in progression-free survival for both 2L and 3L (14.5 mo, P = 0.119 and 3.9 mo, P = 0.882, respectively). Regarding 2L overall survival, we registered a slight increase in neo-RAS wt patients treated with anti-EGFR (33.6 mo vs 32.4 mo, P = 0.385). At data cut-off, two patients were still alive: A RAS-mutated patient undergoing 3L treatment and a neo-RAS wt patient who received 2L treatment with anti-EGFR (ongoing).

CONCLUSION

Our case series demonstrated that monitoring RAS mutations in mCRC by liquid biopsy may provide an additional treatment line for neo-RAS wt patients.

The Effect of Topical Vitamin K1 on the Treatment of Cetuximab-Induced Skin Rashes in Metastatic Colorectal Cancer Patients

Background

Considering the prevalence of cetuximab-induced rashes in colorectal cancer patients and its impact on patient's quality of life and treatment, this study aimed at investigating the effect of topical vitamin K1 on the treatment of skin rashes in metastatic colorectal cancer patients treated with cetuximab.

Materials and Methods

This randomized, controlled, triple-blind, clinical trial was conducted on 49 metastatic colorectal cancer patients who were candidates for cetuximab treatment and referred to Omid Hospital in Isfahan during 2021-2022. Vitamin K1 cream with a concentration of 0.1% in the intervention group (n = 25) and placebo cream in the control group (n = 24) were prescribed twice a day (in the morning and before bedtime) for eight weeks. The rash grade was recorded based on common terminology criteria for adverse events-4 (CTCAE-4) criteria before the intervention and in the fourth and eighth weeks during the intervention.

Results

During the intervention, skin rash grades in the fourth and eighth weeks with the means of 1.00 ± 0.64 and 0.84 ± 0.55, respectively, were significantly lower in the intervention group, as compared with the control group with the means of 1.42 ± 0.65 and 1.25 ± 0.68, respectively (P value < 0.05). Moreover, the severity of skin rashes decreased significantly in the intervention group over time during eight weeks (P value < 0.05); however, its decrease was not significant in the control group (P value > 0.05).

Conclusion

Topical vitamin K1 cream had a significant effect on reducing the severity of cetuximab-induced skin rashes over eight weeks of treatment.

The Therapeutic Landscape for KRAS-Mutated Colorectal Cancers

Colorectal cancer is one of the world's most prevalent and lethal cancers. Mutations of the KRAS gene occur in ~40% of metastatic colorectal cancers. While this cohort has historically been difficult to manage, the last few years have shown exponential growth in the development of selective inhibitors targeting KRAS mutations. Their foremost mechanism of action utilizes the Switch II binding pocket and Cys12 residue of GDP-bound KRAS proteins in G12C mutants, confining them to their inactive state. Sotorasib and Adagrasib, both FDA-approved for the treatment of non-small cell lung cancer (NSCLC), have been pivotal in paving the way for KRAS G12C inhibitors in the clinical setting. Other KRAS inhibitors in development include a multi-targeting KRAS-mutant drug and a G12D mutant drug. Treatment resistance remains an issue with combination treatment regimens including indirect pathway inhibition and immunotherapy providing possible ways to combat this. While KRAS-mutant selective therapy has come a long way, more work is required to make this an effective and viable option for patients with colorectal cancer.

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.

Acquired Genomic Alterations on First-Line Chemotherapy With Cetuximab in Advanced Colorectal Cancer: Circulating Tumor DNA Analysis of the CALGB/SWOG-80405 Trial (Alliance)

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.Acquired genomic alterations (Acq-GAs), specifically RAS, BRAF, and EGFR-ectodomain mutations and ERBB2 and MET amplifications, are recognized as major mechanisms of resistance to later-line anti-EGFR-antibody therapy in metastatic colorectal cancer (mCRC). However, data regarding emergence of these Acq-GAs under the selective pressure of first-line anti-EGFR-chemotherapy are lacking. We performed next-generation sequencing (Guardant360) on circulating tumor DNA obtained from paired plasma samples (pretreatment and postprogression) from the CALGB/SWOG-80405 trial, which randomly assigned patients with mCRC between first-line chemotherapy with cetuximab (anti-EGFR-chemotherapy) or bevacizumab (anti-VEGF-chemotherapy). The primary objective was to determine the prevalence of Acq-GAs on anti-EGFR-chemotherapy and compare this to the prevalence with anti-VEGF-chemotherapy on trial and pooled estimates (N = 292) seen with later-line anti-EGFR-antibody therapy as reported in the literature. Among the 61 patients on anti-EGFR-chemotherapy, only four (6.6%) developed ≥ 1 Acq-GAs of interest compared with 10.1% (7) on anti-VEGF-chemotherapy (odds ratio, 0.62; 95% CI, 0.20 to 2.11) and 62.0% on anti-EGFR-antibody therapy in later lines (odds ratio, 0.09; 95% CI, 0.03 to 0.23). Acq-GAs, classically associated with anti-EGFR-antibody resistance in later lines (RAS, BRAF, and EGFR-ectodomain mutations; ERBB2 and MET amplifications), were rare with up-front use of anti-EGFR-chemotherapy indicating divergent resistance mechanisms. These findings have critical translational relevance to timing and value of circulating tumor DNA-guided anti-EGFR rechallenge in patients with mCRC, especially those treated with anti-EGFR therapy upfront.

Randomized phase II trial of FOLFIRI-panitumumab compared with FOLFIRI alone in patients with RAS wild-type circulating tumor DNA metastatic colorectal cancer beyond progression to first-line FOLFOX-panitumumab: the BEYOND study (GEMCAD 17-01)

PURPOSE

Panitumumab plus FOLFOX (P-FOLFOX) is standard first-line treatment for RAS wild-type (WT) metastatic colorectal cancer. The value of panitumumab rechallenge is currently unknown. We assessed addition of panitumumab to FOLFIRI (P-FOLFIRI) beyond progression to P-FOLFOX in patients with no RAS mutations in liquid biopsy (LB).

METHODS

In this randomized phase II trial, patients were assigned (3:2 ratio) to second-line P-FOLFIRI (arm A) or FOLFIRI alone (arm B). LB for circulating tumor DNA analysis was collected at study entry and at disease progression. Primary endpoint was 6-month progression-free survival. Two-stage Simon design required 85 patients to be included (EudraCT 2017-004519-38).

RESULTS

Between February 2019 and November 2020, 49 patients were screened (16 RAS mutations in LB detected) and 31 included (18 assigned to arm A and 13 to arm B). The study was prematurely closed due to inadequate recruitment. Serious adverse events were more frequent in arm A (44% vs. 23%). Overall response rate was 33% (arm A) vs. 7.7% (arm B). Six-month progression-free survival rate was 66.7% (arm A) and 38.5% (arm B). Median progression-free survival was 11.0 months (arm A) and 4.0 months (arm B) (hazard ratio, 0.58). At disease progression, RAS or BRAF mutations in LB were found in 4/11 patients (36%) in arm A and 2/10 (20%) in arm B.

CONCLUSIONS

The BEYOND study suggests a meaningful benefit of P-FOLFIRI beyond progression to P-FOLFOX in metastatic colorectal cancer patients with WT RAS status selected by LB. This strategy deserves further investigation.

KRAS: A Druggable Target in Colon Cancer Patients

Mutations in KRAS are among the most frequent aberrations in cancer, including colon cancer. KRAS direct targeting is daunting due to KRAS protein resistance to small molecule inhibition. Moreover, its elevated affinity to cellular guanosine triphosphate (GTP) has made the design of specific drugs challenging. Indeed, KRAS was considered ‘undruggable’. KRASG12C is the most commonly mutated variant of KRAS in non-small cell lung cancer. Currently, the achievements obtained with covalent inhibitors of this variant have given the possibility to assess the best therapeutic approach to KRAS-driven tumors. Mutation-related biochemical assets and the tissue of origin are expected to influence responses to treatment. Further attempts to obtain mutant-specific KRAS (KRASG12C) switch-II covalent inhibitors are ongoing and the results are promising. Drugs targeted to block KRAS effector pathways could be combined with direct KRAS inhibitors, immunotherapy or T cell-targeting approaches in KRAS-mutant tumors. The development of valuable combination regimens will be essential against potential mechanisms of resistance that may arise during treatment.

Dissecting the Mechanism of Action of Spiperone-A Candidate for Drug Repurposing for Colorectal Cancer

Simple Summary

Despite advances in primary and adjuvant treatments, approximately 50% of colorectal cancer (CRC) patients still die from recurrence and metastatic disease. Thus, alternative and more effective therapeutic approaches are expected to be developed. Drug repurposing is increasing interest in cancer therapy, as it represents a cheaper and faster alternative strategy to de novo drug synthesis. Psychiatric medications are promising as a new generation of antitumor drugs. Here, we demonstrate that spiperone—a licensed drug for the treatment of schizophrenia—induces apoptosis in CRC cells. Our data reveal that spiperone’s cytotoxicity in CRC cells is mediated by phospholipase C activation, intracellular calcium homeostasis dysregulation, and irreversible endoplasmic reticulum stress induction, resulting in lipid metabolism alteration and Golgi apparatus damage. By identifying new targetable pathways in CRC cells, our findings represent a promising starting point for the design of novel therapeutic strategies for CRC.

Abstract

Approximately 50% of colorectal cancer (CRC) patients still die from recurrence and metastatic disease, highlighting the need for novel therapeutic strategies. Drug repurposing is attracting increasing attention because, compared to traditional de novo drug discovery processes, it may reduce drug development periods and costs. Epidemiological and preclinical evidence support the antitumor activity of antipsychotic drugs. Herein, we dissect the mechanism of action of the typical antipsychotic spiperone in CRC. Spiperone can reduce the clonogenic potential of stem-like CRC cells (CRC-SCs) and induce cell cycle arrest and apoptosis, in both differentiated and CRC-SCs, at clinically relevant concentrations whose toxicity is negligible for non-neoplastic cells. Analysis of intracellular Ca²⁺ kinetics upon spiperone treatment revealed a massive phospholipase C (PLC)-dependent endoplasmic reticulum (ER) Ca²⁺ release, resulting in ER Ca²⁺ homeostasis disruption. RNA sequencing revealed unfolded protein response (UPR) activation, ER stress, and induction of apoptosis, along with IRE1-dependent decay of mRNA (RIDD) activation. Lipidomic analysis showed a significant alteration of lipid profile and, in particular, of sphingolipids. Damage to the Golgi apparatus was also observed. Our data suggest that spiperone can represent an effective drug in the treatment of CRC, and that ER stress induction, along with lipid metabolism alteration, represents effective druggable pathways in CRC.

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.

Clinical Outcomes of Cetuximab and Paclitaxel after Progression on Immune Checkpoint Inhibitors in Recurrent or Metastatic Head and Neck Squamous Cell Carcinoma

Background and Objectives: In recent years, the effectiveness of chemotherapy after immune checkpoint inhibitor administration has attracted attention in various cancers, including head and neck cancers. However, individual assessments of the administered chemotherapy regimens are insufficient. This study aimed to evaluate the efficacy and safety of chemotherapy after immune checkpoint inhibitor administration in recurrent metastatic head and neck cancer by focusing on a single regimen. Materials and Methods: We retrospectively reviewed clinical and radiological data from the medical records of 18 patients with recurrent or metastatic (R/M) head and neck squamous cell carcinoma (HNSCC) who received systemic chemotherapy with weekly cetuximab and paclitaxel (Cmab + PTX) after progression following immune checkpoint inhibitor (ICI) therapy. The objective response rate (ORR) and disease control rate (DCR) were assessed using Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1. Progression-free survival (PFS) and overall survival (OS) were estimated using the Kaplan–Meier method. Adverse events (AEs) were recorded using National Cancer Institute Common Terminology Criteria for Adverse Events, version 4.0. Results: In all patients, the ORR, DCR, median PFS, and median OS were 44.4%, 72.2%, 3.8 months, and 9.6 months, respectively. Regarding AEs, three patients developed grade 3 neutropenia. Grade 3 anemia, paronychia, asthenia, and peripheral neuropathy were observed in one patient each. There were no treatment-related deaths. Conclusions: Cmab + PTX was shown to maintain high efficacy and acceptable safety for R/M HNSCC that progressed after ICI therapy. Further research is needed to establish optimal treatment sequences and drug combinations for recurrent R/M HNSCC.

Current therapy of advanced colorectal cancer according to RAS/RAF mutational status

Colorectal cancer is a clinically and molecularly heterogeneous disease. Currently, extended RAS and BRAF mutation testing is obligatory in routine clinical practice before starting any treatment in the metastatic setting. Treatment decision making also includes assessment of the clinical condition of the patient, definition of the treatment goal, and consideration of the primary tumor site. Biological treatment is part of the first-line drug combination unless contraindicated. Mutational status is significantly associated with the outcome of patients and is strongly predictive for anti-EGFR-targeted therapy. The prognosis of RAS mutant CRC is clearly inferior to wild-type cases. RAS remains an elusive target, and specific treatment options are not yet available. Recently, promising results of a direct KRAS G12C inhibitor have been reported; however, further confirmation is needed. The biomarker landscape in mCRC is evolving; new promising markers are awaited with the chance of more precise targeted treatment.

Tumour heterogeneity and evolutionary dynamics in colorectal cancer

Colorectal cancer (CRC) has a global burden of disease. Our current understanding of CRC has progressed from initial discoveries which focused on the stepwise accumulation of key driver mutations, as encapsulated in the Vogelstein model, to one in which marked heterogeneity leads to a complex interplay between clonal populations. Current evidence suggests that an initial explosion, or “Big Bang”, of genetic diversity is followed by a period of neutral dynamics. A thorough understanding of this interplay between clonal populations during neutral evolution gives insights into the roles in which driver genes may participate in the progress from normal colonic epithelium to adenoma and carcinoma. Recent advances have focused not only on genetics, transcriptomics, and proteomics but have also investigated the ecological and evolutionary processes which transform normal cells into cancer. This review first describes the role which driver mutations play in the Vogelstein model and subsequently demonstrates the evidence which supports a more complex model. This article also aims to underscore the significance of tumour heterogeneity and diverse clonal populations in cancer progression.

Discordance of KRAS Mutational Status between Primary Tumors and Liver Metastases in Colorectal Cancer: Impact on Long-Term Survival Following Radical Resection

Simple Summary

KRAS mutational heterogeneity between primary colorectal cancer and liver metastases may present a challenge in assessing prognostic information prior to the multimodal treatment. Aim of our study is to assess the incidence of KRAS discordance in a single-center series by comparing primary colorectal tumor specimens with the corresponding liver metastasis. Mutation analyses in all patients were performed at the same institution. Impact of discordance on overall survival and risk factors associated with discordance were analyzed. Our study showed that KRAS discordance was observed in 15.9% of patients. In patients with wild-type colorectal primary tumors, subsequent acquisition of mutation in the corresponding liver metastasis was associated with worse overall survival and was significantly more frequently found in patients with multiple liver metastases. These results suggested that, in the era of precision medicine, the possibility of KRAS discordance should be taken into account within the multidisciplinary management of patients with metastatic colorectal cancer.

Abstract

If KRAS mutation status of primary colorectal tumor is representative of corresponding colorectal liver metastases (CRLM) mutational pattern, is controversial. Several studies have reported different rates of KRAS discordance, ranging from 4 to 32%. Aim of this study is to assess the incidence of discordance and its impact on overall survival (OS) in a homogenous group of patients. KRAS mutation status was evaluated in 107 patients resected for both primary colorectal tumor and corresponding CRLM at the same institution, between 2007 and 2018. Discordance rate was 15.9%. Its incidence varied according to the time interval between the two mutation analyses (p = 0.025; Pearson correlation = 0.2) and it was significantly higher during the first 6 months from the time of primary tumor evaluation. On multivariable analysis, type of discordance (wild-type in primary tumor, mutation in CRLM) was the strongest predictor of poor OS (p < 0.001). At multivariable logistic regression analysis, the number of CRLM >3 was an independent risk factor for the risk of KRAS discordance associated with the worst prognosis (OR = 4.600; p = 0.047). Results of our study suggested that, in the era of precision medicine, possibility of KRAS discordance should be taken into account within multidisciplinary management of patients with metastatic colorectal cancer.

Precision Oncology Beyond Genomics: The Future Is Here-It Is Just Not Evenly Distributed

Cancer is a multifactorial disease with increasing incidence. There are more than 100 different cancer types, defined by location, cell of origin, and genomic alterations that influence oncogenesis and therapeutic response. This heterogeneity between tumors of different patients and also the heterogeneity within the same patient's tumor pose an enormous challenge to cancer treatment. In this review, we explore tumor heterogeneity on the longitudinal and the latitudinal axis, reviewing current and future approaches to study this heterogeneity and their potential to support oncologists in tailoring a patient's treatment regimen. We highlight how the ideal of precision oncology is reaching far beyond the knowledge of genetic variants to inform clinical practice and discuss the technologies and strategies already available to improve our understanding and management of heterogeneity in cancer treatment. We will focus on integrating multi-omics technologies with suitable in vitro models and their proficiency in mimicking endogenous tumor heterogeneity.

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

Simple Summary

The survival of patients with metastatic colorectal cancer (mCRC) has been improved over the years and now reaches 30–40 months. However, few therapeutic options are available after failure of first- and second-line treatments. In fact, prognosis of chemo-refractory mCRC remains poor. Therefore, new therapeutic strategies are needed. Emerging evidence suggest that retreatment with epidermal growth factor (EGFR) inhibitors after a treatment break, in patients that obtained a clinical benefit by previous anti-EGFR, could lead to prolonged survival. The rationale beyond this “rechallenge” strategy is that after a “treatment holiday” EGFR resistant cancer cells decay, restoring the sensibility to EGFR blockade. In this review we analyze the current knowledge of retreatment with EGFR inhibitors, examine the role of novel biomarkers that can guide the appropriate selection of patients. Finally, we discuss future perspectives and on-going clinical trials.

Abstract

The prognosis of patients with metastatic colorectal cancer (mCRC) who progressed to the first and the second lines of treatment is poor. Thus, new therapeutic strategies are needed. During the last years, emerging evidence suggests that retreatment with anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (MAbs) in the third line of mCRC patients, that have previously obtained clinical benefit by first-line therapy with anti-EGFR MAbs plus chemotherapy, could lead to prolonged survival. The rationale beyond this “rechallenge” strategy is that, after disease progression to first line EGFR-based therapy, a treatment break from anti-EGFR drugs results in RAS mutant cancer cell decay, restoring the sensitivity of cancer cells to cetuximab and panitumumab. In fact, rechallenge treatment with anti-EGFR drugs has shown promising clinical activity, particularly in patients with plasma RAS and BRAF wild type circulating tumor DNA, as defined by liquid biopsy analysis at baseline treatment. The aim of this review is to analyze the current knowledge on rechallenge and to investigate the role of novel biomarkers that can guide the appropriate selection of patients that could benefit from this therapeutic strategy. Finally, we discuss on-going trials and future perspectives.

Avelumab and cetuximab as a therapeutic combination: An overview of scientific rationale and current clinical trials in cancer

Treatment outcomes have improved with the advent of immune checkpoint inhibitors and small molecule inhibitors. However, many patients do not respond with single agents. Consequently, ongoing research is focused on the use of combination therapies to increase clinical efficacy by potential synergistic effects. Here, we outline ongoing trials and review the rationale and evidence for the combination of avelumab, an anti-programmed death ligand 1 (PD-L1) immunoglobulin G1 (IgG1) monoclonal antibody (mAb), with cetuximab, an anti-epidermal growth factor receptor (EGFR) IgG1 mAb. Avelumab is approved as a monotherapy for the treatment of Merkel cell carcinoma and urothelial carcinoma, and in combination with axitinib for renal cell carcinoma; cetuximab is approved in combination with chemotherapy for the treatment of squamous cell carcinoma of the head and neck (SCCHN) and RAS wild-type metastatic colorectal cancer, and in combination with radiation therapy for SCCHN. Avelumab binds to PD-L1 expressed on tumor cells and immune regulatory cells, thus blocking its interaction with programmed death 1 and reventing T-cell suppression; cetuximab inhibits the EGFR signaling pathway, inhibiting proliferation and inducing apoptosis. Both therapies have complementary mechanisms of action and may also activate the immune system to induce innate effector function through the binding of their Fc regions to natural killer (NK) cells. Furthermore, cetuximab combined with chemotherapy has been shown to induce immunogenic cell death and leads to an increase in tumor-infiltrating CD8+ T and NK cells, which should synergize with the immunostimulatory effects of avelumab. Prospective studies will investigate this combination and inform future treatment strategies.

Extended RAS Analysis of the Phase III EPIC Trial: Irinotecan + Cetuximab Versus Irinotecan as Second-Line Treatment for Patients with Metastatic Colorectal Cancer

BACKGROUND

The multicenter, open-label, randomized, phase III EPIC study (EMR 062202-025) investigated cetuximab plus irinotecan versus irinotecan in patients with epidermal growth factor receptor-detectable metastatic colorectal cancer (mCRC) that progressed on first-line fluoropyrimidine- and oxaliplatin-based chemotherapy; we report the outcomes of patients with RAS-wild-type (wt) disease.

MATERIALS AND METHODS

Available DNA samples from RAS-unselected patients (n = 1,164 of 1,298 [89.7%]) were reanalyzed for RAS mutations using beads, emulsion, amplification, and magnetics. Baseline characteristics, efficacy, safety, and poststudy therapy were assessed. RAS-wt status was defined as a mutated RAS allele frequency of ≤5%, with all relevant alleles being analyzable.

RESULTS

Baseline characteristics were comparable between the groups (n = 452 patients with RAS-wt mCRC; cetuximab plus irinotecan n = 231, irinotecan n = 221) and between the RAS-wt and RAS-unselected populations. In the cetuximab plus irinotecan versus irinotecan arms, median overall survival was 12.3 versus 12.0 months, median progression-free survival (PFS) was 5.4 versus 2.6 months, and objective response rate (ORR) was 29.4% versus 5.0%, respectively. Quality of life (QoL) was improved in the cetuximab plus irinotecan arm. Serious adverse events occurred in 45.4% (cetuximab plus irinotecan) and 42.4% (irinotecan) of patients. In total, 47.1% of patients in the irinotecan arm received subsequent cetuximab therapy.

CONCLUSION

PFS, ORR, and QoL were improved with cetuximab plus irinotecan as a second-line treatment in patients with RAS-wt mCRC, confirming that cetuximab-based therapy is suitable in this population. Almost half of patients in the irinotecan arm received poststudy cetuximab, masking a potential overall survival benefit of cetuximab addition.

IMPLICATIONS FOR PRACTICE

Cetuximab is approved for the treatment of RAS-wild-type metastatic colorectal cancer (mCRC). In this retrospective analysis of the phase III EPIC study (cetuximab plus irinotecan vs. irinotecan alone as second-line treatment in patients with RAS-unselected mCRC), the subgroup of patients with RAS-wild-type mCRC who received cetuximab plus irinotecan had improved progression-free survival, objective response rate, and quality of life compared with the RAS-unselected population. These findings suggest that cetuximab-based therapy is a suitable second-line treatment for patients with RAS-wild-type mCRC.

Effect of Cetuximab-Conjugated Gold Nanoparticles on the Cytotoxicity and Phenotypic Evolution of Colorectal Cancer Cells

Epidermal growth factor receptor (EGFR) is estimated to be overexpressed in 60~80% of colorectal cancer (CRC), which is associated with a poor prognosis. Anti-EGFR targeted monoclonal antibodies (cetuximab and panitumumab) have played an important role in the treatment of metastatic CRC. However, the therapeutic response of anti-EGFR monoclonal antibodies is limited due to multiple resistance mechanisms. With the discovery of new functions for gold nanoparticles (AuNPs), we hypothesize that cetuximab-conjugated AuNPs (cetuximab-AuNPs) will not only improve the cytotoxicity for cancer cells, but also introduce expression change of the related biomarkers on cancer cell surface. In this contribution, we investigated the size-dependent cytotoxicity of cetuximab-AuNPs to CRC cell line (HT-29), while also monitored the expression of cell surface biomarkers in response to treatment with cetuximab and cetuximab-AuNPs. AuNPs with the size of 60 nm showed the highest impact for cell cytotoxicity, which was tested by cell counting kit-8 (CCK-8) assay. Three cell surface biomarkers including epithelial cell adhesion molecule (EpCAM), melanoma cell adhesion molecule (MCAM), and human epidermal growth factor receptor-3 (HER-3) were found to be expressed at higher heterogeneity when cetuximab was conjugated to AuNPs. Both surface-enhanced Raman scattering/spectroscopy (SERS) and flow cytometry demonstrated the correlation of cell surface biomarkers in response to the drug treatment. We thus believe this study provides powerful potential for drug-conjugated AuNPs to enhance cancer prognosis and therapy.

Safety and efficacy of cetuximab-containing chemotherapy after immune checkpoint inhibitors for patients with squamous cell carcinoma of the head and neck: a single-center retrospective study

Immunotherapy has been shown to prolong survival in recurrent or metastatic squamous cell carcinoma of the head and neck (SCCHN) in front-line use; however, subsequent systemic therapy has not been optimized. This study aimed to evaluate the safety and efficacy of cetuximab-containing chemotherapy after immunotherapy. We retrospectively analyzed patients with recurrent or metastatic SCCHN who underwent cetuximab-containing regimens after progression on immunotherapy. Of the 22 patients who met the inclusion criteria, 21 received paclitaxel and cetuximab, and 1 carboplatin and fluorouracil and cetuximab after immunotherapy. Nine patients achieved a partial response, 10 patients had stable disease as their best response on cetuximab-containing chemotherapy, yielding an overall response rate and disease control rate of 40.9 and 86.4%, respectively. The median progression-free survival was 5.2 months, and the median overall survival was 14.5 months. Ten patients developed grade 3-4 adverse events, including neutropenia (31.8%), acneiform rash (9.1%), anemia (4.5%), hypertransaminasemia (4.5%) and stomatitis (4.5%). The most frequent cetuximab-related toxicities across all grades were skin reactions (77.3%), hypomagnesemia (40.9%), stomatitis (27.3%), paronychia (13.6%) and keratitis (4.5%). There was no treatment-related death. Taken together, cetuximab-containing chemotherapy was effective and feasible even after immunotherapy.

Rechallenge with Anti-EGFR Therapy in Metastatic Colorectal Cancer (mCRC): Results from South Australia mCRC Registry

BACKGROUND

Anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (cetuximab or panitumumab) are today increasingly used in the first- or second-line setting for RAS wild-type metastatic colorectal cancer (CRC) patients. Following progression beyond third- or fourth-line therapy, some patients are unsuitable for further chemotherapy because of poor performance status or patient choice. However, a significant number of patients are still candidates for further therapy despite limited standard options being available. The role of rechallenge with anti-EGFR therapy, particularly in patients who had previously responded, is often considered, but there is limited evidence in the literature to support such a strategy.

OBJECTIVE

This retrospective study aims to review the outcome of metastatic CRC patients who had anti-EGFR rechallenge.

PATIENTS AND METHODS

Patients who had been rechallenged with anti-EGFR therapy were identified from the South Australian metastatic CRC database. Patient characteristics were recorded and tumor response was retrospectively assessed using Response Evaluation Criteria in Solid Tumors (RECIST). Kaplan-Meier analysis was used to assess progression free survival (PFS) for each rechallenge and overall survival (OS).

RESULTS

Twenty-two patients were eligible for inclusion in this analysis. Disease control rate (stable disease and partial response) was 45.4% (ten patients) for patients who received rechallenge anti-EGFR. Seven patients received a second rechallenge and disease control rate was 28.6% (two patients). The median interval time between initial anti-EGFR therapy and rechallenge was 13.5 months. The median PFS after rechallenge 1 was 4.1 months and after rechallenge 2 was 3.5 months. The median OS was 7.7 months from date of rechallenge.

CONCLUSIONS

Anti-EGFR rechallenge provides clinical benefit in patients with RAS wild-type metastatic CRC.

Isolation of Common Light Chain Antibodies from Immunized Chickens Using Yeast Biopanning and Fluorescence-Activated Cell Sorting

The phylogenetic distance between chickens and humans accounts for a strong immune response and a broader epitope coverage compared to rodent immunization approaches. Here the authors report the isolation of common light chain (cLC)-based chicken monoclonal antibodies from an anti-epidermal growth factor receptor (EGFR) immune library utilizing yeast surface display in combination with yeast biopanning and fluorescence-activated cell sorting (FACS). For the selection of high-affinity antibodies, a yeast cell library presenting cLC-comprising fragment antigen binding (Fab) fragments is panned against hEGFR-overexpressing A431 cells. The resulting cell-cell-complexes are sorted by FACS resulting in gradual enrichment of EGFR-binding Fabs in three sorting rounds. The isolated antibodies share the same light chain and show high specificity for EGFR, resulting in selective binding to A431 cells with notable EC50 values. All identified antibodies show very good aggregation propensity profiles and thermostabilities. Additionally, epitope binning demonstrates that these cLC antibodies cover a broad epitope space. Isolation of antibodies from immunized chickens by yeast cell biopanning makes an addition to the repertoire of methods for antibody library screening, paving the way for the generation of cLC-based bispecific antibodies against native mammalian receptors.

Intratumoral Transcriptome Heterogeneity Is Associated With Patient Prognosis and Sidedness in Patients With Colorectal Cancer Treated With Anti-EGFR Therapy From the CO.20 Trial

PURPOSE

Metastatic colorectal cancers (mCRCs) assigned to the transit-amplifying (TA) CRCAssigner subtype are more sensitive to anti-epidermal growth factor receptor (EGFR) therapy. We evaluated the association between the intratumoral presence of TA signature (TA-high/TA-low, dubbed as TA-ness classification) and outcomes in CRCs treated with anti-EGFR therapy.

PATIENTS AND METHODS

The TA-ness classes were defined in a discovery cohort (n = 84) and independently validated in a clinical trial (CO.20; cetuximab monotherapy arm; n = 121) and other samples using an established NanoString-based gene expression assay. Progression-free survival (PFS), overall survival (OS), and disease control rate (DCR) according to TA-ness classification were assessed by univariate and multivariate analyses.

RESULTS

The TA-ness was measured in 772 samples from 712 patients. Patients (treated with anti-EGFR therapy) with TA-high tumors had significantly longer PFS (discovery hazard ratio [HR], 0.40; 95% CI, 0.25 to 0.64; P < .001; validation HR, 0.65; 95% CI, 0.45 to 0.93; P = .018), longer OS (discovery HR, 0.48; 95% CI, 0.29 to 0.78; P = .003; validation HR, 0.67; 95% CI, 0.46 to 0.98; P = .04), and higher DCR (discovery odds ratio [OR]; 14.8; 95% CI, 4.30 to 59.54; P < .001; validation OR, 4.35; 95% CI, 2.00 to 9.09; P < .001). TA-ness classification and its association with anti-EGFR therapy outcomes were further confirmed using publicly available data (n = 80) from metastatic samples (PFS P < .001) and patient-derived xenografts (P = .042). In an exploratory analysis of 55 patients with RAS/BRAF wild-type and left-sided tumors, TA-high class was significantly associated with longer PFS and trend toward higher response rate (PFS HR, 0.53; 95% CI, 0.28 to 1.00; P = .049; OR, 5.88; 95% CI, 0.71 to 4.55; P = .09; response rate 33% in TA-high and 7.7% in TA-low).

CONCLUSION

TA-ness classification is associated with prognosis in patients with mCRC treated with anti-EGFR therapy and may further help understanding the value of sidedness in patients with RAS/BRAF wild-type tumors.

Role of Inflammation in the Development of Colorectal Cancer

Chronic inflammation can lead to the development of many diseases, including cancer. Inflammatory bowel disease (IBD) that includes both ulcerative colitis (UC) and Crohnmp's disease (CD) are risk factors for the development of colorectal cancer (CRC). Many cytokines produced primarily by the gut immune cells either during or in response to localized inflammation in the colon and rectum are known to stimulate the complex interactions between the different cell types in the gut environment resulting in acute inflammation. Subsequently, chronic inflammation, together with genetic and epigenetic changes, have been shown to lead to the development and progression of CRC. Various cell types present in the colon, such as enterocytes, Paneth cells, goblet cells, and macrophages, express receptors for inflammatory cytokines and respond to tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, and other cytokines. Among the several cytokines produced, TNF-α and IL-1β are the key pro-inflammatory molecules that play critical roles in the development of CRC. The current review is intended to consolidate the published findings to focus on the role of pro-inflammatory cytokines, namely TNF-α and IL-1β, on inflammation (and the altered immune response) in the gut, to better understand the development of CRC in IBD, using various experimental model systems, preclinical and clinical studies. Moreover, this review also highlights the current therapeutic strategies available (monotherapy and combination therapy) to alleviate the symptoms or treat inflammation-associated CRC by using monoclonal antibodies or aptamers to block pro-inflammatory molecules, inhibitors of tyrosine kinases in the inflammatory signaling cascade, competitive inhibitors of pro-inflammatory molecules, and the nucleic acid drugs like small activating RNAs (saRNAs) or microRNA (miRNA) mimics to activate tumor suppressor or repress oncogene/pro-inflammatory cytokine gene expression.

Circulating Tumor DNA Is Capable of Monitoring the Therapeutic Response and Resistance in Advanced Colorectal Cancer Patients Undergoing Combined Target and Chemotherapy

Colorectal cancer (CRC) is a highly lethal disease worldwide. The majority of patients receiving targeted therapy or chemotherapy develop drug resistance, while its molecular mechanism remains to be elucidated. The plasma circulating tumor DNA (ctDNA) exhibited the potential in identifying gene variations and monitoring drug resistance in CRC treatment. In this study, we monitored the ctDNA mutational changes in advanced CRC patients underwent first-line therapy with bevacizumab and cetuximab combined with chemotherapy. The mutation spectrum of 43 patients was established by a 605-gene next-generation sequencing (NGS) panel. The baseline measurement shows that genes with the highest mutation frequency were TP53 (74%), APC (58%), KRAS (40%), SYNE1 (33%), LRP1B (23%), TOP1 (23%), and PIK3CA (21%). Mutations in TP53, APC, and KRAS were detected in 29 paired plasma and tissue samples with the consistency of 81, 67, and 42%, respectively. Clinically targetable gene mutations, such as APC, RNF43, SMAD4, BRAD1, KRAS, RAF1, and TP53, were also identified in ctDNA. The overall consistency between ctDNA and tissue samples was 54.6%. Alleviation of mutational burden in BRAF, KRAS, AMER1, and other major driving genes was observed following the first-line therapy. Patients with KRAS and TP53 mutations in tissues appeared to benefit more than the wild-type counterpart. The dynamic change of plasma mutation status was consistent with the tissue tumor burden and was closely correlated with disease progression. In conclusion, ctDNA monitoring is a useful method for molecular genotyping of colorectal cancer patients. Dynamic changes in resistance can be sensitively monitored by gene variation status, which potentially helps to develop treatment strategy.

Population-based SEER analysis of survival in colorectal cancer patients with or without resection of lung and liver metastases

Background

Approximately one third of all patients with CRC present with, or subsequently develop, colorectal liver metastases (CRLM). The objective of this population-based analysis was to assess the impact of resection of liver only, lung only and liver and lung metastases on survival in patients with metastatic colorectal cancer (mCRC) and resected primary tumor.

Methods

Ten thousand three hundred twenty-five patients diagnosed with mCRC between 2010 and 2015 with resected primary were identified in the Surveillance, Epidemiology and End Results (SEER) database. Overall, (OS) and cancer-specific survival (CSS) were analyzed by Cox regression with multivariable, inverse propensity weight, near far matching and propensity score adjustment.

Results

The majority (79.4%) of patients had only liver metastases, 7.8% only lung metastases and 12.8% metastases of lung and liver. 3-year OS was 44.5 and 27.5% for patients with and without metastasectomy (HR = 0.62, 95% CI: 0.58–0.65, P < 0.001). Metastasectomy uniformly improved CSS in patients with liver metastases (HR = 0.72, 95% CI: 0.67–0.77, P < 0.001) but not in patients with lung metastases (HR = 0.84, 95% CI: 0.62–1.12, P = 0.232) and combined liver and lung metastases (HR = 0.89, 95% CI: 0.75–1.06, P = 0.196) in multivariable analysis. Adjustment by inverse propensity weight, near far matching and propensity score and analysis of OS yielded similar results.

Conclusions

This is the first SEER analysis assessing the impact of metastasectomy in mCRC patients with removed primary tumor on survival. The analysis provides compelling evidence of a statistically significant and clinically relevant increase in OS and CSS for liver resection but not for metastasectomy of lung or both sites.

Liquid Biopsies in Progressing Metastatic Colorectal Cancer- Application and their Therapeutic Implications According to the RAS Status

Introduction The treatment of metastatic colorectal cancer (mCRC) now includes therapy with biological agents inthe first line of treatment. The advances of our knowledge in molecular biology of these tumors allowed the identification of signaling pathways involved in tumorigenesis as potential therapeutic targets. In this field, monoclonal antibodies against epidermal growth factor receptor (anti-EGFR) added to a chemotherapy doublet have demonstrated improved overall survival for these patients. However, mutations in oncogenes NRAS/KRAS are predictive of absence of response to these treatments. Therefore, genotyping in mCRC is essential to personalized treatment. It is known that tumoral heterogeneity and selective pression by targeted therapies can lead to changes in RAS mutational status, along the course of the disease. This opens the possibility of different targeted therapies. Tumor analysis through liquid biopsies allows for the detection of genetic alterations in a less invasive way than common solid tumor biopsy and is currently being validated in different settings, with promising results in mCRC. The main goal of this study was to assess therapeutic implications of Liquid Biopsy (LB) in treatment of progressive mCRC and its potential impact on survival.  Material and methods A retrospective, observational, unicentric study of patients diagnosed with progressive mCRC and who underwent LB after several lines of treatment, was performed. Analysis of patient and tumor characteristics, as well as LB results was performed with descriptive statistics and survival analysis according to Kaplan-Meier methods and COX analysis with STATA/IC software.  Results We included 18 patients on whom LB were performed (median age 61 years; 55% (n=10) men). The median follow-up was 37.4 months. At diagnosis, 12 patients had a KRAS mutation. In the LB reassessment, there was a change in the RAS status in six patients, who initially had a mutation and later showed KRASwt (wild type RAS). LB led to a change in the therapeutic plan in these six patients, allowing the use of anti-EGFR therapy. Progression Free Survival (PFS) and Overall Survival (OS) could not be calculated at this time. Conclusion LB can revolutionize the approach to mCRC by optimizing therapeutic sequencing in a continuum of care strategy. The search for genetic changes over the course of the disease allows a better therapeutic approach to each patient. In the study presented, the realization of LB allowed an increase in therapeutic options in 1/3 of the patients. It is important to continue these studies with larger samples in order to better validate this strategy.

Emerging Targeted Therapies for HER2 Positive Gastric Cancer That Can Overcome Trastuzumab Resistance

Trastuzumab, a monoclonal antibody to human epidermal growth factor receptor 2 (HER2), has improved survival in patients with HER2-positive advanced gastric or gastroesophageal junction cancer (AGC). The inevitable development of resistance to trastuzumab remains a problem, however, with several treatment strategies that have proven effective in breast cancer having failed to show clinical benefit in AGC. In this review, we summarize the mechanisms underlying resistance to HER2-targeted therapy and outline past and current challenges in the treatment of HER2-positive AGC refractory to trastuzumab. We further describe novel agents such as HER2 antibody-drug conjugates that are under development and have shown promising antitumor activity in early studies.

Cetuximab-conjugated chitosan-pectinate (modified) composite nanoparticles for targeting colon cancer

In the present study, we successfully developed a cetuximab-conjugated modified citrus pectin-chitosan nanoparticles for targeted delivery of curcumin (Cet-MCPCNPs) for the treatment of colorectal cancer. In vitro analyses revealed that nanoparticles were spherical with size of 249.33 ± 5.15 nm, a decent encapsulation efficiency (68.43 ± 2.4%) and a 'smart' drug release profile. 61.37 ± 0.70% of cetuximab was adsorbed to the surface of the nanoparticles. Cellular uptake studies displayed enhanced internalization of Cet-MCPCNPs in Caco-2 (EGFR +ve) cells, which ultimately resulted in a significant reduction in cancer cell propagation. The cell cycle analysis indicated that Cet- MCPCNPs induced cell death in enhanced percentage of Caco-2 cells by undergoing cell cycle arrest in the G2/M phase. These data suggest that Cet-MCPCNPs represent a new and promising targeting approach for the treatment of colorectal cancer.

Detection of RAS mutations in circulating tumor DNA: a new weapon in an old war against colorectal cancer. A systematic review of literature and meta-analysis

Background:

Tissue evaluation for RAS (KRAS or NRAS) gene status in metastatic colorectal cancer (mCRC) patients represent the standard of care to establish the optimal therapeutic strategy. Unfortunately, tissue biopsy is hampered by several critical limitations due to its invasiveness, difficulty to access to disease site, patient’s compliance and, more recently, neoplastic tissue spatial and temporal heterogeneity.

Methods:

The authors performed a systematic literature review to identify available trials with paired matched tissue and ctDNA RAS gene status evaluation. The authors searched EMBASE, MEDLINE, Cochrane, www.ClinicalTrials.gov, and abstracts from international meetings. In total, 19 trials comparing standard tissue RAS mutational status matched paired ctDNA evaluated through polymerase chain reaction (PCR), next generation sequencing (NGS) or beads, emulsions, amplification and magnetics (BEAMing) were identified.

Results:

The pooled sensitivity and specificity of ctDNA were 0.83 (95% CI: 0.80–0.85) and 0.91 (95% CI: 0.89–0.93) respectively. The pooled positive predictive value (PPV) and negative predictive value (NPV) of the ctDNA were 0.87 (95% CI: 0.81–0.92) and 0.87 (95% CI: 0.82–0.92), respectively. Positive likelihood ratio (PLR) was 8.20 (95% CI: 5.16–13.02) and the negative likelihood ratio (NLR) was 0.22 (95% CI: 0.16–0.30). The pooled diagnostic odds ratio (DOR) was 50.86 (95% CI: 26.15–98.76), and the area under the curve (AUC) of the summary receiver operational characteristics (sROC) curve was 0.94.

Conclusion:

The authors’ meta-analysis produced a complete and updated overview of ctDNA diagnostic accuracy to test RAS mutation in mCRC. Results provide a strong rationale to include the RAS ctDNA test into randomized clinical trials to validate it prospectively.

Exploratory findings from a prematurely closed international, multicentre, academic trial: RAVELLO, a phase III study of regorafenib versus placebo as maintenance therapy after first-line treatment in RAS wild-type metastatic colorectal cancer

Background

In patients with RAS wild-type (WT) metastatic colorectal cancer (mCRC), the role of maintenance therapy after first-line treatment with chemotherapy plus antiepidermal growth factor receptor (EGFR) monoclonal antibodies (MoAb) is still an object of debate.

Methods

We assessed the efficacy and safety of regorafenib as a switch maintenance strategy after upfront 5-fluorouracil-based chemotherapy plus an anti-EGFR MoAb in patients with RAS WT mCRC. RAVELLO was a phase III, international, double-blind, placebo-controlled, academic trial. The primary endpoint was progression-free survival (PFS). Secondary endpoints included overall survival and toxicity. Regorafenib or placebo were administered daily for 3 weeks of 4-week cycle until disease progression or unacceptable toxicity, up to 24 months.

Results

The study was stopped prematurely due to slow accrual and lack of funding after the randomisation of 21 patients: 11 in the regorafenib arm and 10 in the placebo arm. The small sample size precludes any statistical analysis. Toxicity was acceptable and consistent with the known regorafenib safety profile. Median PFS was similar in the two arms. However, a subgroup of patients treated with regorafenib experienced a remarkably long PFS. Three patients were progression free at 9 months in the regorafenib arm versus one patient in the placebo arm, whereas at 12 months two regorafenib-treated patients were still progression free versus none in the placebo arm.

Conclusion

RAVELLO trial demonstrated that growing financial and bureaucratic hurdles affect the feasibility of independent academic research. Although stopped prematurely and within the limited sample size, RAVELLO suggests that regorafenib has not a major activity in maintenance setting after upfront chemotherapy and anti-EGFR MoAb. However, a subgroup of patients experienced a remarkable long PFS, indicating that a better refinement of the patient population would help to identify subjects that might benefit from a regorafenib personalised approach in the switch maintenance setting.

The impact of panitumumab treatment on survival and quality of life in patients with RAS wild-type metastatic colorectal cancer

Panitumumab is a fully human monoclonal antibody targeting the epidermal growth factor receptor (EGFR). It is currently approved for the treatment of RAS wild-type (WT) metastatic colorectal cancer (mCRC) in combination with chemotherapy in first- and second-line and as monotherapy in chemorefractory patients. This review will provide an overview of main efficacy data on panitumumab from its early development up to latest evidences, including novel perspectives on predictive biomarkers of anti-EGFRs efficacy and mechanisms of secondary resistance. Quality of life (QoL) related issues and panitumumab safety profile will be addressed as well.

Circulating Tumor DNA Detection in the Management of Anti-EGFR Therapy for Advanced Colorectal Cancer

Background: Anti-EGFR antibodies are a standard care for advanced KRAS-wild type colorectal cancers. Circulating tumor DNA (ctDNA) monitoring during therapy can detect emergence of KRAS mutant clones and early resistance to therapy.

Case Presentation: We describe a 61-years-old man presenting a metastatic and recurrent rectal cancer treated with different chemotherapy regimens. His tumor was KRAS wild-type based on tissue analysis and he was treated sequentially with cetuximab-based chemotherapy, chemotherapy alone and panitumumab-based chemotherapy. We performed sequential analysis of ctDNA using droplet digital PCR (ddPCR) and a commercial assay designed for the detection of frequent KRAS mutations during his clinical follow-up. Prior to the first cetuximab-based chemotherapy ctDNA analysis demonstrated an absence of KRAS mutations. Emergence of KRAS mutations in ctDNA occurred ~3 months after treatment initiation and preceded clinical and imaging progression in about 2 months. Fractional abundance of KRAS mutation rapidly increased to 70.7% immediately before a chemotherapy alone regimen was initiated. Interestingly, KRAS mutation abundance decreased significantly during the first two months of chemotherapy, reaching a fractional abundance of 3.0%, despite minimal clinical benefit with this therapy. Re-challenge with a different anti-EGFR antibody was attempted as later line, but high levels of KRAS mutations in ctDNA before therapy correlated with an absence of clinical benefit.

Conclusions: The monitoring of resistance mutations in KRAS using ctDNA during the treatment of KRAS wild-type advanced colorectal cancers can detect the emergence of resistant clones prior to clinical progression. Dynamics of resistant clones may alter during periods on and off anti-EGFR antibodies, detecting window of opportunities for a re-challenge with these therapies.

Transient Disappearance of RAS Mutant Clones in Plasma: A Counterintuitive Clinical Use of EGFR Inhibitors in RAS Mutant Metastatic Colorectal Cancer

Genomic studies performed through liquid biopsies widely elucidated the evolutionary trajectory of RAS mutant clones under the selective pressure of EGFR inhibitors in patients with wild type RAS primary colorectal tumors. Similarly, the disappearance of RAS mutant clones in plasma has been more recently reported in some patients with primary RAS mutant cancers, supporting for the first time an unexpected negative selection of RAS mutations during the clonal evolution of mCRC. To date, the extent of conversion to RAS wild type disease at the time of progression has not been clarified yet. As a proof of concept, we prospectively enrolled mCRC patients progressing under anti-VEGF based treatments. Idylla™ system was used to screen RAS mutations in plasma and the wild type status of RAS was further confirmed through IT-PGM (Ion Torrent Personal Genome Machine) sequencing. RAS was found mutant in 55% of cases, retaining the same plasma mutation as in the primary tumor at diagnosis, while it was found wild-type in 45%. Four patients testing negative for RAS mutations in plasma at the time of progression of disease (PD) were considered eligible for treatment with EGFR inhibitors and treated accordingly, achieving a clinical benefit. We here propose a hypothetical algorithm that accounts for the transient disappearance of RAS mutant clones over time, which might extend the continuum of care of mutant RAS colorectal cancer patients through the delivery of a further line of therapy.

Retreatment with anti-EGFR monoclonal antibodies in metastatic colorectal cancer: Systematic review of different strategies

BACKGROUND

Despite advances in precision oncology and immunotherapy of tumors, little progress has been made in metastatic colorectal cancer (mCRC) in recent years. Therefore, making the most of available therapies is a necessity. Several studies, based on the pulsatile behavior of RAS clones under EGFR blockade, investigated whether readministration of EGFR-targeted agents is effective beyond second line.

METHODS

A systematic review of studies of retreatment with anti-EGFR monoclonal antibodies has been performed from January 2005 to December 2018 according to PRISMA criteria from PubMed, ESMO and ASCO meetings libraries and Clinicaltrial.gov. Efficacy has been evaluated as objective response rate and survival in available publications. In addition, type and incidence of side effects occurring during on anti-EGFR retreatment have been considered.

RESULTS

26 publications have been retrieved, of which 20 full-text articles and 6 abstracts and categorized as for the retreatment strategy into five groups: rechallenge (n = 10), reintroduction (n = 4), sequence (n = 5), dose escalation (n = 1) and mixed (n = 6). Data of efficacy displayed high heterogeneity across different strategies (objective response rate, ORR = 0.0-53.8%; disease control rate, DCR = 24.0-89.7%), with best results in the setting of rechallenge (ORR = 2.9-53.8%; DCR = 40.0-89.7%).

CONCLUSIONS

Rechallenge with anti-EGFR provides clinical benefit in molecularly selected mCRC patients beyond second line. Further ctDNA-guided studies comparing this option of treatment with current approved advanced line treatments are warranted.

A Phase II study of S-1 plus oral leucovorin in heavily treated metastatic colorectal cancer patients

Purpose

Fewer treatment options are available for refractory metastatic colorectal cancer (mCRC). In early trials, S-1 monotherapy was effective for mCRC patients after chemotherapy failure and its combination with oral leucovorin therapy offers promising results in untreated mCRC. Hence, we conduct a Phase II trial to assess the efficacy of S-1 plus oral leucovorin (SL) in refractory mCRC that progressed after multiple prior standard therapies.

Methods

In this open-label, single-arm study, we enrolled the refractory mCRC patients who received fluoropyrimidine, oxaliplatin, and irinotecan treatment and at least one targeted therapy previously. The doses of SL were 40–60 and 30 mg twice daily separately. They were administered for 7 days in a 2-week cycle. Treatment was continued until disease progression.

Results

Of the 41 enrolled patients, 36 patients were evaluable with 61.1% disease control rate. The median progression-free survival and overall survival were 2.55 and 7.63 months, respectively. Regression change in tumor size stayed 10%–20% in five patients (13.9%) through 18 weeks after treatment, and two patients continued free from tumor progression at 30 and 42 weeks. Compared with moderate heavily pretreated mCRC patient subgroup (≤4 prior regimens), the severe heavily pretreated subgroup (≥5 prior regimens) showed similar disease control rate and survival benefit. Grade 3 or higher toxicities were documented only in 11 patients (26.8%).

Conclusion

SL shows potential as a salvage regimen in refractory mCRC patients especially in the severe heavily pretreated setting and is well tolerated in these patients.

Evaluation of a novel liquid biopsy-based ColoScape assay for mutational analysis of colorectal neoplasia and triage of FIT+ patients: a pilot study

Circulating cell free tumour derived nucleic acids are becoming recognised as clinically significant and extremely useful biomarkers for detection of cancer and for monitoring the progression of targeted drug therapy and immunotherapy. Screening programmes for colorectal cancer in Europe use the Fetal Immunochemical Test (FIT) test as a primary screener. FIT+ patients are referred to immediate colonoscopy and the positive predictive value (PPV) is usually 25%. In this article, we report a study employing the ColoScape assay panel to detect mutations in the APC, KRAS, BRAF and CTNNB1 genes, in order to collect preliminary performance indicators and plan a future, larger population study. The assay was evaluated on 52 prospectively collected whole-blood samples obtained from FIT+ patients enrolled in the CRC screening programme of ASL NAPOLI 3 SUD, using colonoscopy as confirmation. The assay’s sensitivity for advanced adenomas was 53.8% and the specificity was 92.3%. The PPV was 70.0% and negative predicitive value (NPV) was 85.7%. Workflow optimisation is essential to maximise sensitivity. Of note, four of the six positive cases missed by ColoScape had a less than suboptimal DNA input (data not shown). Had they been ruled out as inadequate, sensitivity would have increased from 53.8% to 69%. However, as stated previously, this is not a clinical trial, but rather an initial, preliminary technical evaluation. In conclusion this study shows that ColoScape is a promising tool and further studies are warranted in order to validate its use for the triage of FIT+ patients.