Cetuximab rechallenge in metastatic colorectal cancer patients: how to come away from acquired resistance?

Cell Surface GRP94 as a Novel Emerging Therapeutic Target for Monoclonal Antibody Cancer Therapy

Glucose-regulated protein 94 (GRP94) is an endoplasmic reticulum (ER)-resident member of the heat shock protein 90 (HSP90) family. In physiological conditions, it plays a vital role in regulating biological functions, including chaperoning cellular proteins in the ER lumen, maintaining calcium homeostasis, and modulating immune system function. Recently, several reports have shown the functional role and clinical relevance of GRP94 overexpression in the progression and metastasis of several cancers. Therefore, the current review highlights GRP94’s physiological and pathophysiological roles in normal and cancer cells. Additionally, the unmet medical needs of small chemical inhibitors and the current development status of monoclonal antibodies specifically targeting GRP94 will be discussed to emphasize the importance of cell surface GRP94 as an emerging therapeutic target in monoclonal antibody therapy for cancer.

Detection of Somatic Mutations with ddPCR from Liquid Biopsy of Colorectal Cancer Patients

Liquid biopsy and cell-free DNA (cfDNA) show great promise in cancer diagnostics. In this study, we designed a custom droplet digital PCR (ddPCR) assay for the quantification and quality control of cfDNA isolated from serum. The assay was validated on a group of locally advanced colorectal cancer (CRC) patients and two control groups-patients with hemorrhoids and healthy individuals. The assay shows a high correlation with Qubit measurement (r = 0.976) but offers a higher dynamic range. Mean concentrations of cfDNA were 12.36 ng/µL, 5.17 ng/µL, and 0.29 ng/µL for CRC, hemorrhoid patients, and healthy controls, respectively. The quality of cfDNA was assessed with the measurement of B-cell DNA contamination. On a subset of CRC patients, we compared the mutation status on KRAS (G12A, G12D, G12V, G13D) and BRAF (V600E) genes in the primary tumor and cfDNA isolated from the serum. A total of 70.6% of primary tumor samples were mutated, and the mean fractional abundance of mutations was 9.50%. The matching serum samples were mutated in 38% cases with an average fractional abundance of 0.23%. We conclude that any decisions based solely on the amount of cfDNA present in patient serum must be interpreted carefully and in the context of co-morbidities. This study explores the potential of ddPCR somatic mutations detection from liquid biopsy as a supplement to tissue biopsy in targeted personalized CRC patient management.

Implementing anti-epidermal growth factor receptor (EGFR) therapy in metastatic colorectal cancer: challenges and future perspectives

Epidermal growth factor receptor (EGFR) inhibitors are valuable therapeutics in metastatic colorectal cancer (mCRC). Anti-EGFR monoclonal antibodies (MoAbs), such as cetuximab or panitumumab, in combination with chemotherapy are effective treatment options for patients with RAS and BRAF wild-type mCRC. Nevertheless, several issues are still open concerning the optimal use of anti-EGFR drugs in the continuum of care of mCRC. Novel approaches for increasing the efficacy of anti-EGFR therapies include better molecular selection of EGFR-dependent mCRC, intensification of chemotherapy, combination of anti-EGFR MoAbs and immune checkpoint inhibitors, and reintroduction of EGFR blockade or 'rechallenge' in selected patients who have previously responded to anti-EGFR MoAb therapy. An extensive translational research program was conducted in the Cetuximab After Progression in KRAS wIld-type colorectal cancer patients-Gruppo Oncologico dell' Italia Meridionale (CAPRI-GOIM) study with the aims of determining which subgroups of patients could benefit from the continuous inhibition of EGFR, from evaluating the role of liquid biopsy-based and its concordance with tissue-based molecular testing, and from investigating novel potential mechanisms of resistance to anti-EGFR therapies. In this review, we summarize the translational and clinical findings of the CAPRI-GOIM program in the context of the current knowledge of therapeutic strategies and of ongoing research on more appropriate uses of anti-EGFR therapies in RAS and BRAF wild-type mCRC patients.

ctDNA applications and integration in colorectal cancer: an NCI Colon and Rectal-Anal Task Forces whitepaper

An increasing number of studies are describing potential uses of circulating tumour DNA (ctDNA) in the care of patients with colorectal cancer. Owing to this rapidly developing area of research, the Colon and Rectal-Anal Task Forces of the United States National Cancer Institute convened a panel of multidisciplinary experts to summarize current data on the utility of ctDNA in the management of colorectal cancer and to provide guidance in promoting the efficient development and integration of this technology into clinical care. The panel focused on four key areas in which ctDNA has the potential to change clinical practice, including the detection of minimal residual disease, the management of patients with rectal cancer, monitoring responses to therapy, and tracking clonal dynamics in response to targeted therapies and other systemic treatments. The panel also provides general guidelines with relevance for ctDNA-related research efforts, irrespective of indication.

Phase 2 study of irinotecan plus cetuximab rechallenge as third-line treatment in KRAS wild-type metastatic colorectal cancer: JACCRO CC-08

BACKGROUND

Regorafenib or trifluridine/tipiracil as third-line treatment have limited efficacy in metastatic colorectal cancer (mCRC).

METHODS

This Phase 2 trial evaluated the efficacy and safety of irinotecan plus cetuximab rechallenge as third-line treatment in KRAS wild-type mCRC patients who achieved clinical benefit with first-line cetuximab-containing therapy. The primary endpoint was 3-month progression-free survival (PFS) rate. A sample size was calculated; 30 patients with a 3-month PFS rate of 45% deemed promising and 15% unacceptable. Patients with greater and less than the cut-off value of cetuximab-free intervals (CFIs) were classified into the long and short CFI groups, respectively, in subgroup analyses.

RESULTS

Among 34 eligible patients who received treatment at least once, 3-month PFS rate was 44.1% (95% confidence interval, 27.4-60.8%). The median PFS and overall survival (OS) were 2.4 and 8.2 months, respectively. The response and disease control rates were 2.9 and 55.9%, respectively. PFS and OS were significantly longer in the long- than in the short CFI group.

CONCLUSIONS

Irinotecan plus cetuximab rechallenge as third-line treatment for KRAS wild-type mCRC was safe and had promising activity, especially in those with a long CFI, warranting further investigation in a Phase 3 randomised trial.

CLINICAL TRIAL REGISTRATION

UMIN000010638.

RAS Mutations in Circulating Tumor DNA and Clinical Outcomes of Rechallenge Treatment With Anti-EGFR Antibodies in Patients With Metastatic Colorectal Cancer

PURPOSE

Several trials have evaluated the efficacy of rechallenge treatment with anti–epidermal growth factor receptor (EGFR) monoclonal antibody (mAb) in patients with metastatic colorectal cancer (mCRC). A recent trial indicated that RAS status in circulating tumor DNA (ctDNA) may potentially predict patients with RAS wild-type mCRC resistant to anti-EGFR mAb who would benefit from rechallenge treatment, and the findings should be further investigated.

MATERIAL AND METHODS

We enrolled patients whose plasma samples were collected in prospective phase II trials, the JACCRO CC-08 (n = 36) and CC-09 (n = 25), which evaluated rechallenge chemotherapy with anti-EGFR mAb for KRAS wild-type mCRC. RAS in ctDNA was analyzed at the time points of baseline, 8 weeks, and progression using OncoBEAM RAS CRC kit.

RESULTS

Sixteen patients were enrolled in this study, with a response rate of 0% and a disease control rate (DCR) of 62.5%. RAS mutations were found at baseline in six patients. The DCR was 33% in patients with RAS mutations in ctDNA, whereas it was 80% in patients without RAS mutation at baseline. Patients with RAS mutation at baseline had significantly shorter progression-free survival (PFS) and overall survival (OS) than those without RAS mutation (median PFS, 2.3 v 4.7 months; hazard ratio [HR], 6.2; P = .013; median OS, 3.8 v 16.0 months; HR, 12.4; P = .0028). Six of 10 patients without RAS mutation at baseline acquired RAS mutations at progression. Postprogression survival after rechallenge treatment was numerically shorter in patients with RAS mutation at progression.

CONCLUSION

RAS status in ctDNA was significantly associated with clinical outcomes in patients with mCRC receiving rechallenge treatment with anti-EGFR mAb. These findings could support the clinical utility of OncoBEAM RAS CRC kits for anti-EGFR mAb rechallenge in RAS wild-type mCRC.

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.

Frequency of S492R mutations in the epidermal growth factor receptor: analysis of plasma DNA from patients with metastatic colorectal cancer treated with panitumumab or cetuximab monotherapy

Background

Antibodies against epidermal growth factor receptor (EGFR), panitumumab, a fully human monoclonal antibody, and cetuximab, a human/mouse chimeric monoclonal antibody, have shown clinical efficacy in metastatic colorectal cancer (mCRC). In the phase 3 noninferiority ASPECCT (ClinicalTrials.gov, NCT01001377) study, panitumumab was demonstrated to be noninferior to cetuximab and provided a similar overall survival benefit for patients with chemotherapy-refractory wild-type KRAS exon 2 mCRC. However, some patients eventually develop resistance to anti-EGFR therapy. EGFR p.S492R mutation was previously identified as conferring resistance to cetuximab, but not to panitumumab.

Methods

This biomarker study analyzed plasma samples from ASPECCT collected at both baseline and posttreatment.

Results

No EGFR p.S492R mutations were identified at baseline; however, after treatment the EGFR p.S492R mutation was detected in 1% of patients treated with panitumumab versus 16% of those treated with cetuximab, supporting that, in a large population, this mutation is more likely to be induced by cetuximab than by panitumumab. There were, however, no significant differences in progression-free survival or overall survival between patients who were wild-type compared with those with the S492R mutation within the cetuximab arm or the overall population.

Conclusions

These results may support targeting treatment to small patient subgroups based on the presence of emerging EGFR mutations and provide a molecular rationale for rechallenging with a different anti-EGFR agent in patients who develop resistance. Prospective studies are needed to evaluate the efficacy of panitumumab in the EGFR p.S492R mutant population.

Molecular subtypes and the evolution of treatment management in metastatic colorectal cancer

Colorectal cancer (CRC) is a heterogeneous disease representing a therapeutic challenge, which is further complicated by the common occurrence of several molecular alterations that confer resistance to standard chemotherapy and targeted agents. Mechanisms of resistance have been identified at multiple levels in the epidermal growth factor receptor (EGFR) pathway, including mutations in KRAS, NRAS, and BRAF V600E, and in the HER2 and MET receptors. These alterations represent oncogenic drivers that may co-exist in the same tumor with other primary and acquired alterations via a clonal selection process. Other molecular alterations include DNA damage repair mechanisms and rare kinase fusions, potentially offering a rationale for new therapeutic strategies. In recent years, genomic analysis has been expanded by a more complex study of epigenomic, transcriptomic, and microenvironment features. The Consensus Molecular Subtype (CMS) classification describes four CRC subtypes with distinct biological characteristics that show prognostic and potential predictive value in the clinical setting. Here, we review the panorama of actionable targets in CRC, and the developments in more recent molecular tests, such as liquid biopsy analysis, which are increasingly offering clinicians a means of ensuring optimal tailored treatments for patients with metastatic CRC according to their evolving molecular profile and treatment history.

Readministration of Cancer Drugs in a Patient with Chemorefractory Metastatic Colorectal Cancer

A 63-year-old woman was admitted to our institution for severe pain in her right lower abdomen caused by the perforation of cecal cancer. She underwent emergency surgery, from which she was diagnosed with cecal carcinoma with liver, lung, and lymph node metastases. As she was taking aspirin to prevent cerebral infarction, anti-vascular endothelial growth factor (receptor) antibody and regorafenib therapy were not used. Thus, we started a modified FOLFOX 6+cetuximab regimen. This first-line treatment initially achieved a partial response (PR), but she then developed progressive disease (PD) after 14 months. We changed the regimen to FOLFIRI, followed by trifluridine/tipiracil, but her progression-free survival periods were 2.7 months and 1 month, respectively. Although we cycled through the available array of standard cancer drugs, the patient showed a good performance status, and some benefit from treatment still seemed plausible. We readministered the 5-fluorouracil oral preparation S-1, which maintained stable disease (SD) for 7 months. After PD emerged, we readministered the anti-epidermal growth factor receptor (EGFR) antibody panitumumab for 7.5 months of SD. Finally, 39 months after her diagnosis, she died from rapidly progressing disease. However, her relatively long survival implies that readministering drugs similar to those used in previous regimens might benefit patients with metastatic colorectal cancer.

Is there a role for rechallenge and reintroduction of anti-EGFR plus chemotherapy in later lines of therapy for metastatic colorectal carcinoma? A retrospective analysis

Background

Mechanisms of resistance have been described during disease progression (PD) for patients under treatment with anti-EGFR plus chemotherapy (CT). The aim of our study was to evaluate efficacy of anti-EGFR rechallenge (ReCH) and reintroduction (ReIn) in metastatic colorectal cancer (mCRC).

Materials and methods

This is a retrospective analysis of patients with mCRC that previously received anti-EGFR + CT and interrupted therapy due to PD in the ReCH group and other reasons in the ReIn group. We aimed to describe progression-free survival (PFS), overall survival (OS) and response rate (RR) after re-exposure and to evaluate prognostic factors associated with PFS.

Results

Sixty-eight patients met the inclusion criteria. The median follow-up after re-exposure was 39.3 months. ReCH was adopted in 25% and ReIn in 75%. The median anti-EGFR free interval was at 10.5 months. At re-exposure, the main CT regimen was FOLFIRI in 58.8%. Cetuximab and Panitumumab were used in 59 and 9 patients, respectively. mPFS for ReCH and ReIn was 3.3 × 8.4 months, respectively (p 0.001). The objective response rate for ReCH and ReIn was 18% and 52%, respectively. In univariate analysis, adverse prognostic factors related to PFS were: stable disease or PD at first anti-EGFR exposure (HR: 2.12, CI:1.20-3.74; p = 0.009); ReCH (HR: 3.44, CI:1.88-6.29, p < 0.0001); rechallenge at fourth or later lines (HR: 2.51, CI:1.49-4.23, p = 0.001); panitumumab use (HR: 2.26 CI:1.18-5.54, p = 0.017). In the multivariate model, only ReCH remained statistically significant (HR = 2.63, CI: 1.14-6.03, p = 0.022).

Conclusion

In our analysis, ReCH resulted in short PFS and low RR. However, reintroduction of anti-EGFR plus CT before complete resistance arose resulted in prolonged PFS. These data could be clinically useful to guide a treatment break due to side effects or patient decisions. Our data should be confirmed by larger and prospective trials.

Cetuximab Maintenance Therapy in Patients with Unresectable Wild-Type RAS and BRAF Metastatic Colorectal Cancer: A Single-Institute Prospective Study

INTRODUCTION

Cetuximab plus FOLFIRI (leucovorin, fluorouracil, and irinotecan) is the preferred first-line therapy for RAS and BRAF wild-type (RBWT) metastatic colorectal cancer (mCRC). To counter chemotherapy-induced side effects, use of maintenance therapy is suggested. Therefore, we evaluated the efficacy and safety of cetuximab maintenance therapy in patients after effective completion of first-line induction therapy.

METHODS

This prospective study enrolled untreated patients with mCRC RBWT who received first-line cetuximab plus FOLFIRI therapy. Following this, patients with treatment response either entered observation (stop treatment) or maintenance treatment 1 (cetuximab plus irinotecan) groups. After 6-12 cycles of maintenance treatment 1, patients entered maintenance treatment 2 (cetuximab only). If a patient progressed on maintenance 2, cetuximab plus FOLFIRI was reintroduced. The primary end point was failure-free survival (FFS), whereas the secondary end points included disease control rate (DCR), objective remission rate (ORR), and progression-free survival (PFS). Safety events were also evaluated.

RESULTS

Among 79 enrolled patients, 72 completed first-line treatment effectively (DCR 91.1%, ORR 63.9%) and 44 entered maintenance 1 [median PFS 1 (mPFS, maintenance 1) 6.1 months, 95% confidence interval (CI) 6.0-6.2; DCR 56.8%; ORR 22.7%]. Of them, 21 entered maintenance treatment 2 (mPFS2 8.7 months, 95% CI 3.3-14.1; DCR 28.6%; ORR 4.8%). Median FFS (mFFS) was significantly longer in the maintenance 1 group compared with the observation group [12.7 vs. 3.0 months; hazard ratio (HR) 0.202, 95% CI 0.111-0.369; P < 0.001]. Overall, mFFS was 19.0 and 9.3 months in maintenance and observation groups, respectively (HR 0.211, 95% CI 0.117-0.380; P < 0.001). Rash acneiform, mucositis, and asthenia were commonly observed adverse events during maintenance treatment.

CONCLUSION

Maintenance treatment with cetuximab after first-line therapy significantly improved FFS, with an acceptable safety profile in untreated patients with mCRC RBWT.

TRIAL REGISTRATION

Retrospectively registered, 2019/10/02, Chinese Clinical Trial Registry, ChiCTR number 1900026360.

Molecular-Biology-Driven Treatment for Metastatic Colorectal Cancer

BACKGROUND

Metastatic CRC (mCRC) is a molecular heterogeneous disease. The aim of this review is to give an overview of molecular-driven treatment of mCRC patients.

METHODS

A review of clinical trials, retrospective studies and case reports was performed regarding molecular biomarkers with therapeutic implications.

RESULTS

RAS wild-type status was confirmed as being crucial for anti-epidermal growth factor receptor (EGFR) monoclonal antibodies and for rechallenge strategy. Antiangiogenic therapies improve survival in first- and second-line settings, irrespective of RAS status, while tyrosine kinase inhibitors (TKIs) remain promising in refractory mCRC. Promising results emerged from anti-HER2 drugs trials in HER2-positive mCRC. Target inhibitors were successful for BRAFV600E mutant mCRC patients, while immunotherapy was successful for microsatellite instability-high/defective mismatch repair (MSI-H/dMMR) or DNA polymerase epsilon catalytic subunit (POLE-1) mutant patients. Data are still lacking on NTRK, RET, MGMT, and TGF-β, which require further research.

CONCLUSION

Several molecular biomarkers have been identified for the tailored treatment of mCRC patients and multiple efforts are currently ongoing to increase the therapeutic options. In the era of precision medicine, molecular-biology-driven treatment is the key to impro patient selection and patient outcomes. Further research and large phase III trials are required to ameliorate the therapeutic management of these patients.

Current Options for Third-line and Beyond Treatment of Metastatic Colorectal Cancer. Spanish TTD Group Expert Opinion

Colorectal cancer (CRC) is a public health problem: it is the third most common cancer in men (746,000 new cases/year) and the second in women (614,000 new cases/year), representing the second leading cause of death by cancer worldwide. The survival of patients with metastatic CRC (mCRC) has increased prominently in recent years, reaching a median of 25 to 30 months. A growing number of patients with mCRC are candidates to receive a treatment in third line or beyond, although the optimal drug regimen and sequence are still unknown. In this situation of refractoriness, there are several alternatives: (1) To administer sequentially the 2 oral drugs approved in this indication: trifluridine/tipiracil and regorafenib, which have shown a statistically significant benefit in progression-free survival and overall survival with a different toxicity profile. (2) To administer cetuximab or panitumumab in treatment-naive patients with RAS wild type, which is increasingly rare because these drugs are usually indicated in first- or second-line. (3) To reuse drugs already administered that were discontinued owing to toxicity or progression (oxaliplatin, irinotecan, fluoropyrimidine, antiangiogenics, anti-epidermal growth factor receptor [if RAS wild-type]). High-quality evidence is limited, but this strategy is often used in routine clinical practice in the absence of alternative therapies especially in patients with good performance status. (4) To use specific treatments for very selected populations, such as trastuzumab/lapatinib in mCRC human epidermal growth factor receptor 2-positive, immunotherapy in microsatellite instability, intrahepatic therapies in limited disease or primarily located in the liver, although the main recommendation is to include patients in clinical trials.

Resistance to anti-epidermal growth factor receptor in metastatic colorectal cancer: What does still need to be addressed?

Colorectal cancer (CRC) represents a global health problem, being one of the most diagnosed and aggressive tumors. Cetuximab and panitumumab monoclonal antibodies (mAbs) in combination with chemotherapy are an effective strategy for patients with RAS Wild Type (WT) metastatic colorectal cancer (mCRC). However, tumors are often unresponsive or develop resistance. In the last years, molecular alterations in principal oncogenes (RAS, BRAF, PI3KCA, PTEN) in the downstream pathway of the epidermal growth factor receptor (EGFR) and in other receptors (HER2, MET) that converge on MAPK-ERK signalling have been identified as novel mechanisms of resistance to anti-EGFR strategies. However, further efforts are needed to better stratify CRCs and ensure more individualized treatments. Herein, we describe the consolidated molecular drivers of resistance and the therapeutic strategies available so far, with an overview on potential biomarkers of response that could be integrated in clinical practice.

Update on optimal treatment for metastatic colorectal cancer from the AGITG expert meeting: ESMO congress 2019

Introduction: Outcomes in metastatic colorectal cancer are improving, due to the tailoring of therapy enabled by better understanding of clinical behavior according to molecular subtype.Areas covered: A review of the literature and recent conference presentations was undertaken on the topic of systemic treatment of metastatic colorectal cancer. This review summarizes expert discussion of the current evidence for therapies in metastatic colorectal cancer (mCRC) based on molecular subgrouping.Expert opinion: EGFR-targeted and VEGF-targeted antibodies are now routinely incorporated into treatment strategies for mCRC. EGFR-targeted antibodies are restricted to patients with extended RAS wild-type profiles, with evidence that they should be further restricted to patients with left-sided tumors. Clinically distinct treatment pathways based on tumor RAS, BRAF, HER2 and MMR status, are now clinically applicable. Evidence suggests therapy for additional subgroups will soon be defined; the most advanced being for patients with KRAS G12 C mutation and gene TRK fusion defects.

Treatment of Rectal Cancer-Induced Disseminated Carcinomatosis of the Bone Marrow with FOLFOX plus Cetuximab and Panitumumab

Disseminated carcinomatosis of the bone marrow (DCBM) in colorectal cancer is an extremely rare complication with a poor prognosis. Here, we report a case of DCBM due to rectal cancer successfully treated with a combination of FOLFOX and an anti-epidermal growth factor receptor (EGFR) agent. The patient was a 38-year-old man diagnosed with rectal cancer with multiple bone and para-aortic lymph node metastases complicated by disseminated intravascular coagulation (DIC). He first recovered from DIC following cotreatment with FOLOX plus cetuximab; subsequently, the second attack was successfully treated with FOLFOX plus panitumumab. His initial condition was extremely poor, but he survived with two FOLFOX plus anti-EGFR regimens and died 333 days after introduction of chemotherapy.

Metastatic Colorectal Carcinoma after Second Progression and the Role of Trifluridine-Tipiracil (TAS-102) in Switzerland

BACKGROUND

Metastatic colorectal carcinoma (mCRC) is one of the most prevalent types of cancer worldwide. After tumor progression with first- and second-line treatment, trifluridine (FTD) and tipiracil (TPI) has been shown to be a treatment option.

SUMMARY

Data from a pivotal phase 3 trial (RECOURSE) and an ongoing phase 3b trial (PRECONNECT) have shown that, in mCRC patients who experienced disease progression after 2 lines of standard therapy, treatment with FTD/TPI is safe and efficacious. Other third-line options include regorafenib, rechallenge with previous treatment lines or personalized approaches based on comprehensive molecular profiling. Randomized trials or sequential studies aiming for the right treatment sequence or predefined subtypes for FTD/TPI or regorafenib as well for rechallenge are missing. However, FTD/TPI as well as regorafenib are recommended by the current ESMO, German S3, and National Comprehensive Cancer Network (NCCN) guidelines in the same situation, thus offering physicians a number of alternatives for the treatment of mCRC patients after the second progression. Key Message: This narrative review summarizes published data and their impact for FTD/TPI as well for regorafenib and rechallenge chemotherapy in clinical practice settings of refractory situations of colorectal cancer.

Rechallenge for Patients With RAS and BRAF Wild-Type Metastatic Colorectal Cancer With Acquired Resistance to First-line Cetuximab and Irinotecan: A Phase 2 Single-Arm Clinical Trial

Importance

Based on a small retrospective study, rechallenge with cetuximab-based therapy for patients with KRAS wild-type metastatic colorectal cancer (mCRC) who were previously treated with the same anti-epidermal growth factor receptor-based regimen might be efficacious. Recent data suggest the role of liquid biopsy as a tool to track molecular events in circulating tumor DNA (ctDNA).

Objective

To prospectively assess the activity of cetuximab plus irinotecan as third-line treatment for patients with RAS and BRAF wild-type mCRC who were initially sensitive to and then resistant to first-line irinotecan- and cetuximab-based therapy.

Design, Setting, and Participants

Multicenter phase 2 single-arm trial conducted from January 7, 2015, to June 19, 2017. Liquid biopsies for analysis of ctDNA were collected at baseline. Main eligibility criteria included RAS and BRAF wild-type status on tissue samples; prior first-line irinotecan- and cetuximab-based regimen with at least partial response, progression-free survival of at least 6 months with first-line therapy, and progression within 4 weeks after last dose of cetuximab; and prior second-line oxaliplatin- and bevacizumab-based treatment.

Interventions

Biweekly cetuximab, 500 mg/m2, plus irinotecan, 180 mg/m2.

Main Outcomes and Measures

Overall response rate according to the Response Evaluation Criteria in Solid Tumors, version 1.1. Secondary end points included progression-free survival and overall survival and, as an exploratory analysis, RAS mutations in ctDNA.

Results

Twenty-eight patients (9 women and 19 men; median age, 69 years [range, 45-79 years]) were enrolled. Six partial responses (4 confirmed) and 9 disease stabilizations were reported (response rate, 21%; 95% CI, 10%-40%; disease control rate, 54%; 95% CI, 36%-70%). Primary end point was met because lower limit of 95% CI of response rate was higher than 5%. RAS mutations were found in ctDNA collected at rechallenge baseline in 12 of 25 evaluable patients (48%). No RAS mutations were detected in samples from patients who achieved confirmed partial response. Patients with RAS wild-type ctDNA had significantly longer progression-free survival than those with RAS mutated ctDNA (median progression-free survival, 4.0 vs 1.9 months; hazard ratio, 0.44; 95% CI, 0.18-0.98; P = .03).

Conclusions and Relevance

This is the first prospective demonstration that a rechallenge strategy with cetuximab and irinotecan may be active in patients with RAS and BRAF wild-type mCRC with acquired resistance to first-line irinotecan- and cetuximab-based therapy. The evaluation of RAS mutational status on ctDNA might be helpful in selecting candidate patients.

Trial Registration

ClinicalTrials.gov Identifier: NCT02296203.

Mechanisms of Innate and Acquired Resistance to Anti-EGFR Therapy: A Review of Current Knowledge with a Focus on Rechallenge Therapies

Innate and acquired resistance to anti-EGFR therapy (EGFRi) is a major limitation in the treatment of metastatic colorectal cancer (mCRC). Although RAS genes are the most commonly mutated innate and acquired oncogenes in cancer, there are a number of other mechanisms that limit the effectiveness of EGFRi. Patients with innate resistance have been found to contain BRAFV600E mutations, and possibly MET, MEK, PIK3CA, PTEN, and HER2 alterations. Meanwhile, BRAFV600E mutations may also be involved in acquired resistance to EGFRi, in addition to EGFR ectodomain mutations, MET alterations, and possibly HER2 amplification. In addition, paracrine effects and cell-fate mechanisms of resistance are being increasingly described as contributing to acquired resistance. Utilization of circulating tumor DNA has been paramount in monitoring the dynamic nature of acquired resistance and has helped to guide treatment decisions, particularly in the EGFRi rechallenge setting. Herein, we provide an in-depth review of EGFRi-resistance mechanisms and describe the current therapeutic landscape in the hopes of identifying effective rechallenge strategies.

Emergence of KRAS p.G13D mutation and acquired resistance to cetuximab in colorectal cancer with vulvar metastasis: A case report

RATIONALE

Vulvar metastasis of colorectal cancer (CRC) and acquired resistance to cetuximab is a very rare phenomenon. To our knowledge, few cases have been reported in the English literatures.

PATIENT CONCERNS

A 55-year-old woman was diagnosed as adenocarcinoma of the rectum and the primary tumor was detected to be Kirsten-RAS (KRAS) wild type.

DIAGNOSES

The patient was diagnosed with rectal adenocarcinoma by colonoscopy. Positron emission tomography/computed tomography (PET-CT) revealed multiple lymph node and bone metastases.

INTERVENTIONS

The patient received a first-line course of palliative chemotherapy with FOLFOX combined with cetuximab.

OUTCOMES

After an initial response, acquired resistance to cetuximab occurred and vulvar metastasis was established by a second biopsy. Further molecular analysis showed that the KRAS mutation was detected in plasma samples and tumor tissues.

LESSONS

Vulvar metastasis from CRC is relatively rare and indicates a poor prognosis. Routine physical examinations of cutaneous and subcutaneous may facilitate early detection of metastases and timely intervention of medical technology. Moreover, combining serial tumor biopsy, liquid biopsy, and radiologic imaging could help to define mechanisms of drug resistance and to guide selection of therapeutic strategies.

Targeting EGFR and RAS/RAF Signaling in the Treatment of Metastatic Colorectal Cancer: From Current Treatment Strategies to Future Perspectives

The epidermal growth factor receptor (EGFR) and RAS/RAF signaling pathway plays pivotal roles in tumor progression via proliferation, survival, invasion, and immune evasion. Two anti-EGFR monoclonal antibodies, cetuximab and panitumumab, have become essential components in the treatment of patients with metastatic colorectal cancer (mCRC). Treatment with these anti-EGFR antibodies has shown definite benefits when administered in all treatment lines and is strongly recommended as the preferred regimen to prolong survival, especially when administered in the first- and third-lines. Recent efforts have revealed not only mechanisms responsible for resistance to anti-EGFR antibodies, including expanded RAS mutations as a negative predictive biomarker, but also the possibility of continuing anti-EGFR antibody treatment in combination with chemotherapy. Furthermore, the challenges associated with the pharmaceutical development of treatments for patients with mutant-type BRAF mCRC are ongoing. In this review, we provide an overview of the EGFR and RAS/RAF signaling pathway and antitumor activity, focusing on practical aspects such as established treatments including patient selection, treatment strategies, and future perspectives for drug development targeting the EGFR and RAS/RAF signaling pathway.

Effect of KRAS mutational status on disease behavior and treatment outcome in patients with metastatic colorectal cancer: intratumor heterogeneity and mutational status

Background

Nowadays, the outcomes of metastatic colorectal cancer (mCRC) have considerably improved. Genetic studies evaluating KRAS mutational status are important in the personalized therapy era to understand disease heterogeneity, disease behaviors, and treatment outcomes.

Methods

This multicenter retrospective study evaluated 360 patients with mCRC treated at three oncology centers in Saudi Arabia and Egypt between February 2011 and December 2015. Patients were treated with bevacizumab and cetuximab according to guidelines. Therapy outcome, time to progression, and disease-associated death were assessed. KRAS mutational status was evaluated by testing exons 12 and 13.

Results

Approximately 220 (61.1%) cases were of wild-type KRAS, whereas KRAS mutation was noted in 38.9%. KRAS mutation was common in the descending colon, whereas a low incidence of the KRAS mutation was observed in the ascending colon (P<0.001). Among patients with KRAS mutation, 64.3% initially presented as emergency cases with obstruction/perforation (P=0.002), and 62.9% had hepatic or pulmonary metastasis. The progression-free survival (PFS) was 10.7 months. Cases without KRAS mutation showed a higher PFS than did those with KRAS mutation (mean PFS: 11.5 vs. 9.6 months, P=0.001). The overall survival was 23.2 months. The survival varied considerably according to KRAS type: patients without mutation survived for 25.0 months and those with mutation survived for 19.6 months (P<0.001). Disease-related death occurred in 132 (36.7%) cases, approximately 57.1% of them (80 cases) had KRAS mutations (P=0.001).

Conclusions

A major association between KRAS mutational status and both disease behavior and treatment outcomes was found in this study. Patients with KRAS mutation show advanced disease presentation, with lower PFS and overall survival.

Systemic steroid treatment can desensitize the skin reaction due to regorafenib in a recurrence colorectal cancer patient

Oral intake of regorafenib has been shown to have survival benefits in patients with metastatic colorectal cancer progressing on standard therapies. However, because of adverse effects, the patients sometimes cannot continue treatment with regorafenib. Currently, there is no established supportive therapy that can be performed to aid in continuing regorafenib intake under these problematic conditions. We report the case of a 59-year-old Japanese woman diagnosed with recurrence after curative operation for sigmoid colon cancer (T3N2aM0, Stage IIIC). Despite undergoing multiple lines of standard chemotherapy, disease control could not be maintained. Consequently, regorafenib was started as a late-line treatment. However, after 2 weeks, the patient experienced regorafenib-induced serious erythema multiforme; thus, regorafenib was discontinued and oral prednisolone was started. Regorafenib administration was resumed when the adverse effects resolved and prednisolone was stopped, but skin rash rapidly reappeared. Prednisolone treatment was reintroduced, which cured the rash; thus, after the third attempt to administer regorafenib, prednisolone was continuously administered. There was no relapse of the rash under prednisolone administration, and the patient received a total of 13 courses of regorafenib. Moreover, the metastatic lesions that had started to regrow at the end of the regorafenib therapy showed good response to the rechallenge chemotherapy of folinic acid, fluorouracil, and irinotecan therapy with panitumumab. The sequence of therapies possibly had a positive impact on the patient's long survival of 30 months after the regorafenib treatment. Systemic administration of steroid is considered as a promising option as a supportive therapy for continuing regorafenib treatment in patients experiencing a severe skin rash.

Distinguishing Features of Cetuximab and Panitumumab in Colorectal Cancer and Other Solid Tumors

Cetuximab and panitumumab are two distinct monoclonal antibodies (mAbs) targeting the epidermal growth factor receptor (EGFR), and both are widely used in combination with chemotherapy or as monotherapy to treat patients with RAS wild-type metastatic colorectal cancer. Although often considered interchangeable, the two antibodies have different molecular structures and can behave differently in clinically relevant ways. More specifically, as an immunoglobulin (Ig) G1 isotype mAb, cetuximab can elicit immune functions such as antibody-dependent cell-mediated cytotoxicity involving natural killer cells, T-cell recruitment to the tumor, and T-cell priming via dendritic cell maturation. Panitumumab, an IgG2 isotype mAb, does not possess these immune functions. Furthermore, the two antibodies have different binding sites on the EGFR, as evidenced by mutations on the extracellular domain that can confer resistance to one of the two therapeutics or to both. We consider a comparison of the properties of these two antibodies to represent a gap in the literature. We therefore compiled a detailed, evidence-based educational review of the known molecular, clinical, and functional differences between the two antibodies and concluded that they are distinct therapeutic agents that should be considered individually during treatment planning. Available data for one agent can only partly be extrapolated to the other. Looking to the future, the known immune activity of cetuximab may provide a rationale for this antibody as a combination partner with investigational chemotherapy plus immunotherapy regimens for colorectal cancer.

Retreatment with Vismodegib after Progression in Advanced Basal Cell Carcinoma: First-Time Report of a Single-Institution Experience

Retreatment with vismodegib in advanced basal cell carcinoma (BCC) patients who previously discontinued the drug due to disease progression (PD) has not been reported yet. The objective of our report is to determine whether vismodegib is still active when used in BCC patients who progressed during a first vismodegib course (FVC). We conducted a retrospective study on six advanced BCC patients enrolled in a clinical trial (STEVIE, NCT01367665) who discontinued vismodegib due to PD and were then retreated with the same drug. All patients underwent intercurrent therapies between the FVC and the second vismodegib course (SVC). Disease control (complete response, CR; partial response, PR; and stable disease) was achieved in 100% and 80% of cases in FVC and SVC, respectively. The overall response rate was 80% for FVC (50% of CR) and 50% for SVC (only PR). Median treatment duration of FVC and SVC was 19.5 months (range: 13-35) and 8 months (range: 3-14+), respectively. G3-G4 AEs were reported only during SVC (two cases), leading to permanent discontinuation in one case. The median interval between FVC and SVC was 21.5 months (range: 13-30). After a median follow-up of 54 months (range: 46-63) only one patient with metastatic disease had rapid progression, discontinued vismodegib, and died. All other patients are still alive and two are currently on therapy. We concluded that vismodegib rechallenge is feasible and potentially active in advanced BCC patients who previously discontinued the drug due to disease progression.

The Evolving Biomarker Landscape for Treatment Selection in Metastatic Colorectal Cancer

The approval of targeted therapies for metastatic colorectal cancer (mCRC) has led to important improvements in patient outcomes. However, it is still necessary to increase individualisation of treatments based on tumour genetic profiles to optimise efficacy, while minimising toxicity. As such, there is currently great focus on the discovery and validation of further biomarkers in mCRC, with many new potential prognostic and predictive markers being identified alongside developments in patient molecular profiling technologies. Here, we review data for validated and emerging biomarkers impacting treatment strategies in mCRC. We completed a structured literature search of the PubMed database to identify relevant publications, limiting for English-language publications published between 1 January 2014 and 11 July 2018. In addition, we performed a manual search of the key general oncology and CRC-focused congresses to identify abstracts reporting emerging mCRC biomarker data, and of ClinicalTrials.gov to identify ongoing clinical trials investigating emerging biomarkers in mCRC and/or molecular-guided clinical trials. There is solid evidence supporting the use of BRAF status as a prognostic biomarker and DYPD, UGT1A1, RAS, and microsatellite instability as predictive biomarkers in mCRC. There are a number of emerging biomarkers that may prove to be clinically relevant in the future to have prognostic (HPP1 methylation), predictive (HER3, microRNAs, anti-angiogenic markers, and CRC intrinsic subtypes), or both prognostic and predictive values (HER2, CpG island methylator phenotype, tumour mutational load, gene fusions, and consensus molecular subtypes). As such, new biomarker-led treatment strategies in addition to anti-epidermal growth factor receptor and anti-angiogenetic treatments are being explored. Biomarkers that are not recommended to be tested in clinical practice or are unlikely to be imminently clinically relevant for mCRC include thymidylate transferase, ERCC1, PIK3CA, and PTEN. We highlight the clinical utility of existing and emerging biomarkers in mCRC and provide recommended treatment strategies according to the biomarker status. An update on ongoing molecular-guided clinical trials is also provided.

Emergence of RAS mutations in patients with metastatic colorectal cancer receiving cetuximab-based treatment: a study protocol

Background

In the management of patients with RAS wild-type metastatic colorectal cancer (mCRC), anti-epidermal growth factor receptor (EGFR) therapies have demonstrated a clinical benefit, with longer survival. However, the correlation between the emergence of circulating RAS mutations and secondary resistance to anti-EGFR therapies requires further elucidation. In this study, we aim to examine evolutionary changes in RAS mutations through liquid biopsy in patients with mCRC during and after anti-EGFR therapy.

Methods

A total of 120 patients diagnosed with RAS wild-type mCRC will be enrolled in this study. Patients will receive a cetuximab-based infusional 5-fluorouracil regimen as first-line treatment. Cetuximab-based treatment is expected to continue until disease progression, intolerable toxic effects, or withdrawal of consent. Blood samples from enrolled patients will be collected before and then every 3 months during cetuximab-based treatment and also at disease progression. These blood samples will be evaluated for RAS resistance mutations by using the MassARRAY platform. The primary endpoint is the percentage of RAS mutations detected in circulating DNA from patients during cetuximab treatment. The correlation between the tumor response and survival outcomes of these patients and the emergence of circulating RAS mutations will be further analyzed.

Discussion

Liquid biopsy is a powerful technology that can represent tumor heterogeneity in a relatively noninvasive manner. Because RAS mutations play a major role in resistance to anti-EGFR therapy for mCRC, examining evolutionary changes in these mutations during such treatment through liquid biopsy would be useful. After comprehensively analyzing the emergence of circulating RAS mutations and its clinical relevance in this study, our results should provide practical guidance on anti-EGFR therapy for mCRC.

Trial registration

The date of trial registration (NCT03401957) in this study was January 17, 2018.

Electronic supplementary material

The online version of this article (10.1186/s12885-019-5826-7) contains supplementary material, which is available to authorized users.

Response to the Rechallenge With Talimogene Laherparepvec (T-VEC) After Ipilimumab/Nivolumab Treatment in Patient With Cutaneous Malignant Melanoma Who Initially Had a Progression on T-VEC With Pembrolizumab

Talimogene laherparepvec (T-VEC) is approved for unresected stage III-IV malignant melanoma. T-VEC has a direct cytotoxic effect and enhances the antitumor immunity of host cells. Immune checkpoints inhibitors also enhance the immunity of host cells by increasing the recruitment of antigen-presenting cells or activation and restoration of T-cell functions. Both type of therapies can potentiate the effect of the other therapy. We are reporting a case of T-VEC rechallenge who initially progressed on T-VEC with pembrolizumab but then responded to T-VEC rechallenge after intervening ipilimumab/nivolumab. An 83-year-old man developed a subungual lesion of the left thumb and found to have AJCC V. 7 stage IIIb melanoma. Few months later, he developed axillary lymphadenopathy and multiple subcutaneous nodules (AJCC V. 7 stage IIIc). The patient was started on intralesional rose Bengal and pembrolizumab. After 4 cycles of pembrolizumab with rose Bengal, a positron-emission tomography/computerized tomography scan showed the progression of disease. He was started on T-VEC intralesional injections with concurrent pembrolizumab, however, after 3 T-VEC injections and 2 more cycles of pembrolizumab, there was the progression of disease. Subsequently, ipilimumab/nivolumab was started and patient responded partially. Ipilimumab/nivolumab was held due to toxicity. Eight weeks from the last dose of ipilimumab/nivolumab, he experienced locoregional progression and was rechallenged with T-VEC monotherapy. The patient showed a significant response after second T-VEC injection and continued to show response 6 months since rechallenge. After, initial progression on T-VEC with pembrolizumab, intervening immune checkpoints inhibitors may favorably modify the antitumor immunity and potentiate antitumor effect of T-VEC rechallenge.

Phase I study of the anti-heparin-binding epidermal growth factor-like growth factor antibody U3-1565 with cetuximab in patients with cetuximab- or panitumumab-resistant metastatic colorectal cancer

KRAS wild-type colorectal cancers initially responsive to anti-endothelial growth factor receptor (EGFR) antibodies [cetuximab (Cetu)/panitumumab (Pani)] develop acquired resistance. Overexpression of EGFR ligands such as heparin-binding EGF-like growth factor (HB-EGF) may be one resistance mechanism. This phase I study of U3-1565, anti-HB-EGF antibody, and Cetu combination therapy enrolled patients with KRAS wild-type metastatic colorectal cancer who had received two ≤ regimens with fluoropyrimidine, oxaliplatin, irinotecan, and Cetu/Pani and had disease progression on Cetu/Pani. Recommended dose (RD) was determined in the 1st stage, followed by evaluation of efficacy at the RD level in the 2nd-stage. Cetu was given at a loading dose of 400 mg/m² followed by weekly infusions of 250 mg/m² in levels 1 and 0. U3-1565 was administered at a loading dose of 24 mg/m² followed by biweekly infusions of 16 mg/m² in level 1 and 16-12 mg/m² in level 0. Twenty-two patients were enrolled. No dose-limiting toxicities were observed among three patients in level 1 in the first stage, which was determined as RD. Grade 3 or higher adverse events occurred in 59.1%; those in ≥5% of patients were anemia, γ-GTP elevation, and acneiform rash. Overall response rate was 0.0% [95% confidence interval (CI): 0.0%-15.4%] and disease control was achieved in 17 patients (77.3%, 95% CI: 54.6%-92.2%). Median progression-free survival time was 85.0 days (95% CI: 54.0-91.0) and median survival time was 196 days (95% CI: 113.0-306.0). RD was determined as level 1. The efficacy of this combination therapy after progression on Cetu/Pani was negligible. Trial Registration: UMIN000013006.

Clinical utility of circulating tumor DNA for colorectal cancer

Colorectal cancer (CRC) is currently the most common type of cancer in Japan, and its prognosis has improved because of development of diagnosis and advancement in treatments including surgery and chemotherapy. However, because of intratumor heterogeneity and clonal evolution, tumors often develop resistance to treatment. Genotyping tumor tissue in search of somatic genetic alterations for actionable information has become routine examination in clinical practice. However, the inherent molecular heterogeneity of metastatic tumors and the ability of cancer genomes to dynamically evolve are not properly captured by tissue specimens only. Circulating tumor DNA (ctDNA) carrying tumor‐specific genetic or epigenetic alterations is released into the circulation from tumor cells undergoing apoptosis or necrosis. Analysis of ctDNA has the potential to change clinical practice by exploiting blood rather than tissue, as a source of information. Here, we provide an overview of the characteristics of ctDNA and focus on detection methods for ctDNA, and the feasibility of use of ctDNA to monitor tumor dynamics for patients with colorectal cancer.

Systemic treatment for metastatic colorectal cancer in the era of precision medicine

The treatment of metastatic colorectal cancer has evolved over the last two decades with the FDA approval of several cytotoxic, biological, and targeted agents. In this paper, we review the impact of sidedness, RAS, BRAF, HER-2, and other immune biomarkers on metastatic colorectal cancer treatment selection and sequencing in both the palliative and curative intent settings.

Anti-EGFR-resistant clones decay exponentially after progression: implications for anti-EGFR re-challenge

BACKGROUND

Colorectal cancer (CRC) has been shown to acquire RAS and EGFR ectodomain mutations as mechanisms of resistance to epidermal growth factor receptor (EGFR) inhibition (anti-EGFR). After anti-EGFR withdrawal, RAS and EGFR mutant clones lack a growth advantage relative to other clones and decay; however, the kinetics of decay remain unclear. We sought to determine the kinetics of acquired RAS/EGFR mutations after discontinuation of anti-EGFR therapy.

PATIENTS AND METHODS

We present the post-progression circulating tumor DNA (ctDNA) profiles of 135 patients with RAS/BRAF wild-type metastatic CRC treated with anti-EGFR who acquired RAS and/or EGFR mutations during therapy. Our validation cohort consisted of an external dataset of 73 patients with a ctDNA profile suggestive of prior anti-EGFR exposure and serial sampling. A separate retrospective cohort of 80 patients was used to evaluate overall response rate and progression free survival during re-challenge therapies.

RESULTS

Our analysis showed that RAS and EGFR relative mutant allele frequency decays exponentially (r2=0.93 for RAS; r2=0.94 for EGFR) with a cumulative half-life of 4.4 months. We validated our findings using an external dataset of 73 patients with a ctDNA profile suggestive of prior anti-EGFR exposure and serial sampling, confirming exponential decay with an estimated half-life of 4.3 months. A separate retrospective cohort of 80 patients showed that patients had a higher overall response rate during re-challenge therapies after increasing time intervals, as predicted by our model.

CONCLUSION

These results provide scientific support for anti-EGFR re-challenge and guide the optimal timing of re-challenge initiation.

Combination of Irinotecan, Oxaliplatin and 5-Fluorouracil as a Rechallenge Regimen for Heavily Pretreated Metastatic Colorectal Cancer Patients

PURPOSE

Our objective was to evaluate the benefit of re-exposing patients with refractory metastatic colorectal cancer (mCRC) to a combination of oxaliplatin, irinotecan and 5-fluorouracil treatment.

METHODS

We retrospectively analysed patients with mCRC who received a combination of oxaliplatin, irinotecan and fluorouracil as a rechallenge regimen after progressing on the same drugs. Both FOLFOXIRI and FOLFIRINOX were used. Toxicity was evaluated for each treatment cycle, and survival analysis was performed using the Kaplan-Meier method.

RESULTS

A total of 21 patients who were treated between January 2011 and December 2013 were selected for this study. Most of the patients (95.2%) had an ECOG status of 0-1. The median age at diagnosis was 52.1 years (range 36-77 years), and 14 (66.6%) patients had wild-type KRAS. Thirteen patients received FOLFIRINOX, and eight received FOLFOXIRI. Most patients had previously received at least three regimens, with 80% receiving anti-VEGF and 66% anti-EGFR antibodies. The response rate was 38%, and 24% patients had stable disease. The median time to disease progression was 4.0 months (range 1.0-9.1 months), and the median overall survival duration was 8.6 months (range 6.3-11.5 months). Most patients required dose adjustment and treatment delays. One patient experienced grade 5 neutropenic sepsis.

CONCLUSIONS

Both FOLFIRINOX and FOLFOXIRI are active and potentially feasible rechallenge treatment options for heavily pretreated patients with good performance status. With dose reduction and close monitoring for toxicity, the risk of serious adverse events can be minimised.

Treatment sequencing in metastatic colorectal cancer

Metastatic colorectal cancer (mCRC) remains incurable in most cases, but survival has improved with advances in cytotoxic chemotherapy and targeted agents. However, the optimal use and sequencing of these agents across multiple lines of treatment is unclear. Here, we review current treatment approaches and optimal treatment sequencing across the first-, second- and third-line settings in mCRC, including biological aspects affecting sequencing and rechallenge. Effective first-line therapy is a key determinant of treatment outcomes and should be selected after considering both clinical factors and biological markers, notably RAS and BRAF. The second-line regimen choice depends on the systemic therapies given in first-line. Anti-angiogenic agents (e.g. bevacizumab, ramucirumab and aflibercept) are indicated for most patients, whereas epidermal growth factor receptor (EGFR) inhibitors do not improve survival in the second-line setting. Molecular profiling is important in third-line treatment, with options in RAS wild-type patients including EGFR inhibitors (cetuximab or panitumumab), regorafenib and trifluridine/tipiracil. Immunotherapy with pembrolizumab or nivolumab ± ipilimumab may be considered for patients with high microsatellite instability disease. Targeting HER2/neu amplification shows promise for the subset of CRC tumours displaying this abnormality. Sequencing decisions are complicated by the potential for any treatment break or de-escalation to evoke a distinct clinical progression type. Ongoing trials are investigating the optimal sequencing and timing of therapies for mCRC. Molecular profiling has established new targets, and increasing knowledge of tumour evolution under drug pressure will possibly impact on sequencing.

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.

Third- or Later-line Therapy for Metastatic Colorectal Cancer: Reviewing Best Practice

An increasing number of patients with metastatic colorectal cancer (mCRC) are able to receive 3 or more lines of therapy. Treatments in this setting can include regorafenib (an oral multikinase inhibitor), trifluridine/tipiracil hydrochloride (TAS-102), antibodies that target epidermal growth factor receptor for patients with RAS wild-type tumors (if no prior exposure), and, where approved, anti-programmed cell death protein 1 inhibitors for patients with microsatellite instability-high mCRC. Although guidelines describe the available treatment options, few insights are provided to guide selection and sequencing. In this article, we share expert opinion from diverse geographic regions, to offer guidance for best practice when selecting and managing third-line treatment for mCRC. Various factors, including performance status, age, and tumor sidedness, can be used to guide treatment selection. Biomarkers, such as RAS, BRAF, and microsatellite instability, can be useful for treatment stratification. Management of adverse events, to maintain quality of life, is a key consideration and is crucial to best practice in this setting. Common toxicities associated with third-line treatments are hand-foot skin reaction, fatigue, diarrhea, and cytopenias. Patients who receive third-line and later-line treatments should be monitored for these events, especially during the first 2 cycles. Dose modifications can also be used to manage toxicities and to minimize the effect on quality of life, while maximizing treatment benefit. Clinical trials of emerging agents, new treatment combinations, and novel therapies continue the efforts to improve outcomes for patients with mCRC. Sharing expert opinions on best practice for treatment selection and management can ultimately improve outcomes for patients with mCRC.

Targeted therapy for metastatic colorectal cancer

INTRODUCTION

Outcomes in metastatic colorectal cancer are improving, with better understanding and use of targeted therapies. Areas covered: A review of the literature and recent conference presentations was undertaken on the topic of systemic treatment of metastatic colorectal cancer. This article reviews the current evidence for targeted therapies in advanced colorectal cancer, including up-to-date data regarding anti-epidermal growth factor receptor (EGFR) and anti-vascular endothelial growth factor (VEGF) agents, the relevance of primary tumor location and novel subgroups such as BRAF mutated, HER2 amplified, and mismatch-repair-deficient cancers. Expert commentary: EGFR-targeted and VEGF-targeted antibodies are now routinely incorporated into treatment strategies for metastatic colorectal cancer (mCRC). The use of EGFR-targeted antibodies should be restricted to patients with extended RAS wild-type profiles, and there is evidence that they should be further restricted to patients with left-sided tumors. Clinically, mCRC can be divided into subgroups based on RAS, BRAF, HER2, and MMR status, each of which have distinct treatment pathways.

Relationships between tumour response and primary tumour location, and predictors of long-term survival, in patients with RAS wild-type metastatic colorectal cancer receiving first-line panitumumab therapy: retrospective analyses of the PRIME and PEAK clinical trials

BACKGROUND

Data from two trials of panitumumab in metastatic colorectal cancer (mCRC) were retrospectively analysed to investigate the effects of primary tumour location on early-tumour shrinkage (ETS) and depth of response (DpR), and identify factors predicting long-term survival.

METHODS

Patients with RAS wild-type mCRC from PRIME (NCT00364013) and PEAK (NCT00819780) were included. ETS was defined as a ≥30% reduction in the sum-of-the-longest-diameters of measurable target lesions at eight weeks. DpR was the maximum percentage change from baseline to nadir in patients with shrinkage. Univariate and multivariate logistic analyses of short- versus long-term survivor data were performed.

RESULTS

A total of 435/559 (78%) patients had left-sided disease. Of these, a higher proportion of patients treated with panitumumab versus comparator achieved ETS (PRIME: 62% vs. 36%; PEAK: 58% vs. 41%); median DpR was also higher with panitumumab (PRIME: 59% vs. 49%; PEAK: 70% vs. 48%). In pooled analyses of the studies, more patients with right-sided disease achieved ETS if treated with panitumumab than comparator (39% vs. 29%). Panitumumab treatment consistently predicted long-term survival.

CONCLUSIONS

First-line panitumumab was associated with improved ETS and DpR vs. comparator in patients with left-sided mCRC. ETS may identify a subgroup of patients with right-sided disease who might respond to panitumumab.

Cetuximab retreatment in patients with metastatic colorectal cancer who exhibited a clinical benefit in response to prior cetuximab: A retrospective study

Clinical benefits of cetuximab retreatment in patients with metastatic colorectal (mCRC) have been reported. In the present study, the effect of cetuximab retreatment on predictive markers was investigated by evaluating the clinical benefit of initial cetuximab treatment prior to cetuximab retreatment. Between November 2012 and March 2017, 14 patients with KRAS proto-oncogene GTPase exon 2 wild-type mCRC who exhibited a clinical benefit (confirmed stable disease for at least 6 months or a clinical response) to an initial cetuximab-based regimen, who received multiple lines of chemotherapy following disease progression and ultimately received a second cetuximab and irinotecan regimen, were retrospectively analyzed. For retreatment, patients received bi-weekly irinotecan (120-150 mg/m²) combined with cetuximab (400 mg/m² as an initial dose, followed by 250 mg/m², weekly). The median age of the 14 patients (11 males, 3 females) was 68 years (32-77). The median progression-free survival (PFS) following prior cetuximab-based therapy was 6.6 months (range, 4.1-18.4). Initial cetuximab treatment was administered as a first-line treatment in 11 patients, a second-line treatment in 1 patient and a third-line treatment in 2 patients. The median interval time between the last cycle of initial cetuximab-based therapy and the first cycle of cetuximab retreatment was 13.1 months (range, 6.0-37.1). The objective response rate of cetuximab retreatment was 21.4% and the median PFS was 4.4 months (95% confidence interval, 1.4-5.6). The Spearman's correlation coefficient for the PFS following retreatment and duration of initial cetuximab-based regimens demonstrated a more marked correlation compared with that between the PFS following retreatment and the interval time between the two regimens (r=0.45, P=0.11 vs. r=0.08, P=0.79). Cetuximab retreatment may provide clinical benefit to patients with mCRC who were good responders with longer periods of initial cetuximab-based therapy.

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

The anti-epidermal growth factor receptor (EGFR) monoclonal antibody cetuximab in combination with chemotherapy is a standard of care in the first-line treatment of RAS wild-type (wt) metastatic colorectal cancer (mCRC) and has demonstrated efficacy in later lines. Progressive disease (PD) occurs when tumours develop resistance to a therapy, although controversy remains about whether PD on a combination of chemotherapy and targeted agents implies resistance to both components. Here, we propose that some patients may gain additional clinical benefit from the reuse of cetuximab after having PD on regimens including cetuximab in an earlier treatment line. We conducted a non-systematic literature search in PubMed and reviewed published and ongoing clinical trials, focusing on later-line cetuximab reuse in patients with mCRC. Evidence from multiple studies suggests that cetuximab can be an efficacious and tolerable treatment when continued or when fit patients with mCRC are retreated with it after a break from anti-EGFR therapy. Furthermore, on the basis of available preclinical and clinical evidence, we propose that longitudinal monitoring of RAS status may identify patients suitable for such a strategy. Patients who experience progression on cetuximab plus chemotherapy but have maintained RAS wt tumour status may benefit from continuation of cetuximab with a chemotherapy backbone switch because they have probably developed resistance to the chemotherapeutic agents rather than the biologic component of the regimen. Conversely, patients whose disease progresses on cetuximab-based therapy due to drug-selected clonal expansion of RAS-mutant tumour cells may regain sensitivity to cetuximab following a defined break from anti-EGFR therapy. Looking to the future, we propose that RAS status determination at disease progression by liquid, needle or excisional biopsy may identify patients eligible for cetuximab continuation and rechallenge. With this approach, treatment benefit can be extended, adding to established continuum-of-care strategies in patients with mCRC.

Incorporating BEAMing technology as a liquid biopsy into clinical practice for the management of colorectal cancer patients: an expert taskforce review

The importance of mutation identification for advanced colorectal cancer treatment with anti-epidermal growth factor receptor agents is well established. However, due to delays in turnaround time, low-quality tissue samples, and/or lack of standardization of testing methods a significant proportion of patients are being treated without the information that Kirsten rat sarcoma and neuroblastoma rat sarcoma (RAS) testing can provide. The detection of mutated circulating tumor DNA by BEAMing technology addresses this gap in care and allows these patients to receive international guideline-recommended expanded RAS testing with rapid turnaround times. Furthermore, the overall concordance between OncoBEAM RAS colorectal cancer testing and standard of care tissue testing is very high (93.3%). This article presents an overview of the clinical utility and potential applications of this minimally invasive method, such as early detection of emergent resistance to anti-epidermal growth factor receptor therapy. If appropriately implemented, BEAMing technology holds considerable promise to enhance the quality of patient care and improve clinical outcomes.

Emergence of KRAS-mutation in liver metastases after an anti-EGFR treatment in patient with colorectal cancer: Are we aware of the therapeutic impact of intratumor heterogeneity?

Tumors represent a dynamic system where the genomic plasticity permits to adapt to the perturbation induced by environmental pressures, supporting the importance of longitudinal tumor sampling strategies to deciphering the temporal acquisition of driver event that could impact treatment outcome. We describe the case of a metastatic colorectal cancer (mCRC) patient, RAS wild-type, who responded to anti-EGFR therapy and underwent liver surgery, revealing a KRAS mutations in the metastatic lesion, not detectable prior to initiation of therapy in the colonic biopsy. After liver surgery, the patient received chemotherapy alone, then underwent left colectomy and the final pathological report confirmed the KRAS wild-type status. We can speculate the existence of two distinct populations of KRAS wild-type and mutant CRC cells sharing the same genetic origin. The anti-EGFR treatment represented a selective pressure which allowed the selection of KRAS mutant subclones. The prognostic and /or predictive role of intratumor heterogeneity has not been assessed prospectively. Our case report is of clinical relevance because patients with mCRC who respond to anti-EGFR antibodies often develop resistance within several months of initiating therapy, thus outlining the importance to better ascertain the molecular landscape of tumors to design better therapeutic strategies.

Beyond second-line therapy in patients with metastatic colorectal cancer: a systematic review

Background

The optimal chemotherapeutic regimen for use beyond the second line for patients with metastatic colorectal cancer (mCRC) remains unclear.

Materials and methods

We systematically searched the Cochrane Database of Systematic Reviews, EMBASE and Medline for records published between January 2002 and May 2017, and cancer congress databases for records published between January 2014 and June 2017. Eligible studies evaluated the efficacy, safety and patient-reported outcomes of monotherapies or combination therapies at any dose and number of treatment cycles for use beyond the second line in patients with mCRC. Studies were assessed for design and quality, and a qualitative data synthesis was conducted to understand the impact of treatment on overall survival and other relevant cancer-related outcomes.

Results

The search yielded 938 references of which 68 were included for qualitative synthesis. There was limited evidence to support rechallenge with chemotherapy, targeted therapy or both. Compared with placebo, an overall survival benefit for trifluridine/tipiracil (also known as TAS-102) or regorafenib has been shown for patients previously treated with conventional chemotherapy and targeted therapy. There was no evidence to suggest a difference in efficacy between these treatments. Patient choice and quality of life at this stage of treatment should also be considered when choosing an appropriate therapy.

Conclusions

These findings support the introduction of an approved agent such as trifluridine/tipiracil or regorafenib beyond the second line before any rechallenge in patients with mCRC who have failed second-line treatment.