The best strategy for metastatic colorectal cancer (mCRC) patients in second-line treatment: A network meta-analysis

BACKGROUND

Varieties of systemic treatments in second-line treatment for metastatic colorectal cancer (mCRC) patients have showed an improvement on survival. In this study, we performed a systematic review with a pairwise and bayesian network meta-analysis to rank the best strategy for mCRC patients in second-line treatment.

METHODS

A systematic literature search through 2007 was performed to evaluate the association between several treatment combinations and overall survival (OS), progression-free survival (PFS) and disease control rate (DCR) in mCRC patients. Data were carried out and pooled into a statistical indirect comparison with Bayesian network meta-analysis (NMA).

RESULTS

10 trials totally comprised 4183 patients were included in our study. In NMA, For PFS, Doublet+Bev showed benefits in comparing with Doublet, Doulblet+placebo and Doublet+Ramucirumab. Also, Doublet+Aflibercept demonstrated its superiority in comparing with Doulblet+placebo. For OS, Doublet+Bev represented its superiority when comparing with Double and Doublet+placebo. Doublet+Aflibercept and Doublet+Ramucirumab also done well when opposed to Doublet+placebo. For DCR, Doublet+bev showed unique superiority when compared with Doublet, And Doublet+targeted agent did not represent benefits to each other in DCR. Doublet+bev ranked highest in terms of PFS, OS and DCR followed by Doublet+panitumumab, Doublet+placebo was the lowest in terms of PFS and OS.

CONCLUSIONS

Our study shows that Doublet+Bev has the major probability to provide an improvement of survival in patients with mCRC.

Safety and efficacy of panitumumab in combination with trifluridine/tipiracil for pre-treated patients with unresectable, metastatic colorectal cancer with wild-type RAS: The phase 1/2 APOLLON study

Background

We aimed to assess the safety and efficacy of combination treatment with panitumumab plus trifluridine/tipiracil (FTD/TPI) in patients with wild-type RAS metastatic colorectal cancer (mCRC) who were refractory/intolerant to standard therapies other than anti-epidermal growth factor receptor therapy.

Methods

APOLLON was an open-label, multicentre, phase 1/2 trial. In the phase 1 part, 3 + 3 de-escalation design was used to investigate the recommended phase 2 dose (RP2D); all patients in the phase 2 part received the RP2D. The primary endpoint was investigator-assessed progression-free survival (PFS) rate at 6 months. Secondary endpoints included PFS, overall survival (OS), overall response rate (ORR), disease control rate (DCR), time to treatment failure (TTF), and safety.

Results

Fifty-six patients were enrolled (phase 1, n = 7; phase 2, n = 49) at 25 Japanese centres. No dose-limiting toxicities were observed in patients receiving panitumumab (6 mg/kg every 2 weeks) plus FTD/TPI (35 mg/m² twice daily; days 1–5 and 8–12 in a 28-day cycle), which became RP2D. PFS rate at 6 months was 33.3% (90% confidence interval [CI] 22.8–45.3). Median PFS, OS, ORR, DCR, and TTF were 5.8 months (95% CI 4.5–6.5), 14.1 months (95% CI 12.2–19.3), 37.0% (95% CI 24.3–51.3), 81.5% (95% CI 68.6–90.8), and 5.8 months (95% CI 4.29–6.21), respectively. Neutrophil count decreased (47.3%) was the most common Grade 3/4 treatment-emergent adverse event. No treatment-related deaths occurred.

Conclusion

Panitumumab plus FTD/TPI exhibited favourable anti-tumour activity with a manageable safety profile and may be a therapeutic option for pre-treated mCRC patients.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10147-021-01902-2.

Metastatic colorectal cancer (mCRC): French intergroup clinical practice guidelines for diagnosis, treatments and follow-up (SNFGE, FFCD, GERCOR, UNICANCER, SFCD, SFED, SFRO, SFR)

INTRODUCTION

This document is a summary of the French intergroup guidelines regarding the management of metastatic colorectal cancer (mCRC) published in January 2019, and available on the French Society of Gastroenterology website (SNFGE) (www.tncd.org).

METHODS

This collaborative work was realized by all French medical and surgical societies involved in the management of mCRC. Recommendations are graded in three categories (A, B and C), according to the level of evidence found in the literature, up until December 2018.

RESULTS

The management of metastatic colorectal cancer has become complex because of increasing available medical, radiological and surgical treatments alone or in combination. The therapeutic strategy should be defined before the first-line treatment, mostly depending on the presentation of the disease (resectability of the metastases, symptomatic and/or threatening disease), of the patient's condition (ECOG PS, comorbidities), and tumor biology (RAS, BRAF, MSI). The sequence of targeted therapies also seems to have an impact on the outcome (angiogenesis inhibition beyond progression). Surgical resection of metastases was the only curative intent treatment to date, joined recently by percutaneous tumor ablation tools (radiofrequency, microwave). Localized therapies such as hepatic intra-arterial infusion, radioembolization and hyperthermic intraperitoneal chemotherapy, also have seen their indications specified (liver-dominant disease and resectable peritoneal carcinomatosis). New treatments have been developed in heavily pretreated patients, increasing overall survival and preserving quality of life (regorafenib and trifluridine/tipiracil). Finally, immune checkpoint inhibitors have demonstrated high efficacy in MSI mCRC.

CONCLUSION

French guidelines for mCRC management are put together to help offer the best personalized therapeutic strategy in daily clinical practice, as the mCRC therapeutic landscape is complexifying. These recommendations are permanently being reviewed and updated. Each individual case must be discussed within a multidisciplinary team (MDT).

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.

Silencing of RHEB inhibits cell proliferation and promotes apoptosis in colorectal cancer cells via inhibition of the mTOR signaling pathway

Colorectal cancer (CRC) is commonly known as one of the most prominent reasons for cancer-related death in China. Ras homolog enriched in brain (RHEB) and the mammalian target activity of rapamycin (mTOR) signaling pathway were found correlated with CRC, but their specific interaction in CRC was still to be investigated. Therefore, we explored whether RHEB gene silencing affected the cell proliferation, differentiation, and apoptosis by directly targeting the mTOR signaling pathway in cells previously harvested from CRC patients. A microarray analysis was subsequently conducted to investigate the relationship between RHEB and mTOR. Eighty-three adjacent normal tissues and CRC tissues were selected. Immunohistochemistry was carried out to detect the positive expression rates of RHEB and Ki-67 in the CRC tissues. Cells were then transfected with different siRNAs to investigate the potential effects RHEB would have on CRC progression. The expressions of RHEB, 4EBP1, ribosomal protein S6 kinase (p70S6K), proliferating cell nuclear antigen (PCNA), B cell lymphoma 2 (bcl-2), and bcl-2-associated X protein (bax) were determined and then the cell cycle, cell proliferation, and apoptotic rate were also measured. We identified RHEB and mTOR as upregulated genes in CRC. Cells treated with RHEB silencing showed a decreased extent of mTOR, p70S6K, 4EBP1 phosphorylation and expression of RHEB, Ki-67, mTOR, p70S6K, 4EBP1, bcl-2, and PCNA as well as decreased activity of cell proliferation and differentiation; although, the expression of bax was evidently higher. Collectively, our data propose the idea that RHEB gene silencing might repress cell proliferation and differentiation while accelerating apoptosis via inactivating the mTOR signaling pathway.

Clinical Pharmacokinetics and Pharmacodynamics of the Epidermal Growth Factor Receptor Inhibitor Panitumumab in the Treatment of Colorectal Cancer

Despite progress in the treatment of metastatic colorectal cancer (mCRC) in the last 15 years, it is still a condition with a relatively low 5-year survival rate. Panitumumab, a fully human monoclonal antibody directed against the epidermal growth factor receptor (EGFR), is able to prolong survival in patients with mCRC. Panitumumab is used in different lines of therapy in combination with chemotherapy, and as monotherapy for the treatment of wild-type (WT) RAS mCRC. It is administered as an intravenous infusion of 6 mg/kg every 2 weeks and has a t_½ of approximately 7.5 days. Elimination takes place via two different mechanisms, and immunogenicity rates are low. Only RAS mutations have been confirmed as a negative predictor of efficacy with anti-EGFR antibodies. Panitumumab is generally well tolerated and has a manageable toxicity profile, despite a very high prevalence of dermatologic side effects. This article presents an overview of the clinical pharmacokinetics and pharmacodynamics of panitumumab, including a description of the studies that led to its approval in the different lines of therapy of mCRC.

Optimizing sequential treatment with anti-EGFR and VEGF mAb in metastatic colorectal cancer: current results and controversies

Anti-EGFR mAb (cetuximab or panitumumab) and anti-VEGF mAb (bevacizumab) are the two main targeted agents available for RAS wild-type (WT) metastatic colorectal cancer (mCRC) treatment. Nonetheless, three head-to-head clinical trials evaluating anti-EGFR mAb vs -VEGF mAb in first-line treatment failed to conclude a uniform result. Recently, a few small clinical studies revealed that prior use of bevacizumab may impair the effect of cetuximab or panitumumab. Preclinical studies have also suggested that pretreatment with bevacizumab may lead to simultaneous resistance to anti-EGFR mAb. Therefore, we performed this review to summarize the available data regarding the optimal sequential treatment of anti-EGFR and -VEGF mAb for RAS or KRAS WT mCRC and discuss the potential mechanisms that may explain this phenomenon. Primary tumor location and early tumor shrinkage have emerged as new potential prognostic and predictive factors in mCRC. We also collected information to explore whether these factors affect the optimal sequencing of targeted therapy in mCRC. However, definite conclusions cannot be made, and we can only speculate on optimal treatment recommendations based on the contradictory results.

Sequential therapy with bevacizumab and EGFR inhibitors for metastatic colorectal carcinoma: a national registry-based analysis

Purpose

Although inhibitors of vascular endothelial growth factor and inhibitors of epidermal growth factor receptor (EGFRi) are commonly used for the treatment of metastatic colorectal cancer (mCRC), the optimal sequencing of these agents is currently unclear.

Methods

A national registry of targeted therapies was used to analyze baseline characteristics and outcomes of patients with mCRC and wild-type KRAS exon 2 status who received bevacizumab and EGFRi (cetuximab or panitumumab) as a part of first- and second-line treatment in either sequence.

Results

The cohort included 490 patients (181 patients treated with first-line EGFRi and second-line bevacizumab and 309 patients treated with first-line bevacizumab and second-line EGFRi). Median overall survival (OS) from the initiation on first-line therapy was similar for patients treated with either sequence, reaching 31.8 (95% CI 27.5-36.1) vs 31.4 months (95% CI 27.8-35.0) for EGFRi → bevacizumab vs bevacizumab → EGFRi cohort, respectively. Time from first-line initiation to progression on the second-line therapy [progression-free survival (PFS)] was 21.1 (95% CI 19.3-23.0) vs 19.3 months (95% CI 17.3-21.3) for bevacizumab → EGFRi vs EGFRi → bevacizumab cohort, respectively (P=0.016).

Conclusion

This retrospective analysis of real-world data of patients with wild-type KRAS exon 2 mCRC showed no differences in OS between cohorts treated with bevacizumab → EGFRi vs the reverse sequence while combined PFS favored the bevacizumab → EGFRi sequence.

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.

Biologic Response of Colorectal Cancer Xenograft Tumors to Sequential Treatment with Panitumumab and Bevacizumab

Recent studies in RAS wild-type (WT) metastatic colorectal cancer (mCRC) suggest that the survival benefits of therapy using anti-epidermal growth factor receptor (anti-EGFR) and anti-vascular endothelial growth factor (anti-VEGF) antibodies combined with chemotherapy are maximized when the anti-EGFR antibody is given as first-line, followed by subsequent anti-VEGF antibody therapy. We report reverse-translational research using LIM1215 xenografts of RAS WT mCRC to elucidate the biologic mechanisms underlying this clinical observation. Sequential administration of panitumumab then bevacizumab (PB) demonstrated a stronger tendency to inhibit tumor growth than bevacizumab then panitumumab (BP). Cell proliferation was reduced significantly with PB (P < .01) but not with BP based on Ki-67 index. Phosphoproteomic analysis demonstrated reduced phosphorylation of EGFR and EPHA2 with PB and BP compared with control. Western blotting showed reduced EPHA2 expression and S897-phosphorylation with PB; RSK phosphorylation was largely unaffected by PB but increased significantly with BP. In quantitative real-time PCR analyses, PB significantly reduced the expression of both lipogenic (FASN, MVD) and hypoxia-related (CA9, TGFBI) genes versus control. These results suggest that numerous mechanisms at the levels of gene expression, protein expression, and protein phosphorylation may explain the improved clinical activity of PB over BP in patients with RAS WT mCRC.