Treatment dilemmas of cetuximab combined with chemotherapy for metastatic colorectal cancer

Although monoclonal antibodies (mAbs) against epidermal growth factor receptor (EGFR) have largely enriched the available therapeutic choices for colorectal cancer (CRC), the understanding and management of their associated clinical toxicities are limited. In addition, the combined strategies of administering EGFR mAbs and traditional cytotoxic agents, such as 5-fluorouracil, oxaliplatin and irinotecan, have resulted in a more complicated management of CRC treatment-related side effects compared with EGFR mAb monotherapy. We believe that a thorough recognition of the toxicities of EGFR mAb drugs is essential for physicians to increase the therapeutic index in the treatment of CRC. This review aims to summarize the existing information regarding the treatment dilemmas of cetuximab combined with chemotherapy in the management of metastatic CRC.     

Cetuximab in combination with chemoradiotherapy in Chinese patients with non-resectable,locally advanced esophageal squamous cell carcinoma: A prospective,multicenter phase II trail

Background and purpose

This multicenter phase II trial investigated cetuximab combined with chemoradiotherapy in patients with esophageal squamous cell carcinoma (ESCC).

Material and methods

Eligible patients with non-resectable, locally-advanced ESCC received cetuximab 400 mg/m² loading dose on day 1; and on day 1 of the 2nd–7th weeks: cetuximab 250 mg/m², paclitaxel 45 mg/m², and cisplatin 20 mg/m², concurrent with 59.4 Gy/33 fractions of radiation therapy. Primary endpoint was clinical response rate. Secondary endpoints included overall survival (OS), progression-free survival (PFS), safety, and KRAS status.

Results

Of 55 patients enrolled, 45 completed therapy. Forty-four patients had a clinical response: 29 complete response and 15 partial response. One-year PFS and OS of 45 evaluable patients were 84.23% and 93.33%, respectively, and 2-year PFS and OS were 74.87% and 80.00%, respectively. Non-hematologic adverse events were generally grade 1 or 2; primarily rash (92.7%), mucositis (45.5%), fatigue (41.8%), and nausea (38.2%). Grade 3 hematologic adverse events included neutropenia (32.7%) and anemia (1.8%). No KRAS mutations were identified in 50 evaluated samples.

Conclusions

Cetuximab can be safely administered with chemoradiotherapy to patients with locally-advanced ESCC and may improve clinical response rate.     

Dual EGFR inhibition in combination with anti-VEGF treatment: A phase I clinical trial in non-small cell lung cancer

BACKGROUND

Preclinical data indicate EGFR signals through both kinase-dependent and independent pathways and that combining a small-molecule EGFR inhibitor, EGFR antibody, and/or anti-angiogenic agent is synergistic in animal models.

METHODS

We conducted a dose-escalation, phase I study combining erlotinib, cetuximab, and bevacizumab. The subset of patients with non-small cell lung cancer (NSCLC) was analyzed for safety and response.

RESULTS

Thirty-four patients with NSCLC (median four prior therapies) received treatment on a range of dose levels. The most common treatment-related grade &ge;2 adverse events were rash (n=14, 41%), hypomagnesemia (n=9, 27%), and fatigue (n=5, 15%). Seven patients (21%) achieved stable disease (SD) &ge;6 months, two achieved a partial response (PR) (6%), and two achieved an unconfirmed partial response (uPR) (6%) (total=32%). We observed SD&ge;6 months/PR/uPR in patients who had received prior erlotinib and/or bevacizumab, those with brain metastases, smokers, and patients treated at lower dose levels. Five of 16 patients (31%) with wild-type EGFR experienced SD&ge;6 months or uPR. Correlation between grade of rash and rate of SD&ge;6 months/PR was observed (p<0.01).

CONCLUSION

The combination of erlotinib, cetuximab, and bevacizumab was well-tolerated and demonstrated antitumor activity in heavily pretreated patients with NSCLC.     

Comparison of KRAS Genotype: Therascreen Assay vs. LNA-Mediated qPCR Clamping Assay

BackgroundKirsten rat sarcoma virus (KRAS) wild-type status determined using a locked nucleic acid (LNA)-mediated quantitative polymerase chain reaction (qPCR) clamping assay (LNA assay) predicted response to therapy in the CRYSTAL (Cetuximab Combined With Irinotecan in First-Line Therapy for Metastatic Colorectal Cancer) study. A companion KRAS diagnostic tool has been developed for routine clinical use (QIAGEN therascreen kit) (QIAGEN Manchester Ltd, Manchester, UK). We wanted to assess the concordance between the validated US Food and Drug Administration (FDA)-approved therascreen assay and the LNA assay in determining the KRAS status of a subset of patients enrolled in the CRYSTAL study.Patients and MethodsDNA extracted from paraffin-embedded tumor sections was tested for KRAS status using the therascreen assay. Efficacy data from the CRYSTAL study were assessed to determine if the overall survival (OS) hazard ratio for cetuximab in patients identified as having KRAS wild-type status using the therascreen assay was equivalent to that in patients identified as KRAS wild-type using the LNA assay. This was determined by assessing if the concordance between the therascreen assay and the LNA assay met the minimum threshold (prespecified as 0.8) to achieve a significant difference in the OS hazard ratio in favor of the cetuximab + FOLFIRI (5-fluorouracil, leucovorin [folinic acid], irinotecan) arm in the KRAS wild-type population as identified using the therascreen assay.ResultsOf the 148 samples determined to be KRAS wild-type (therascreen assay), 141 (95.3%) samples were also KRAS wild-type (LNA assay) and 7 samples (4.7%) were KRAS mutant (LNA assay). The prespecified primary concordance measure p was 141/148 = 0.953 (95% confidence interval [CI], 0.905-0.981). The concordance was statistically significantly higher than the prespecified threshold of 0.8 for concordance between the therascreen assay and the LNA assay. Consistent with the concordance exceeding the prespecified threshold, the OS hazard ratio (cetuximab + FOLFIRI arm vs. FOLFIRI arm) in the KRAS wild-type population, determined by the therascreen assay, supported a significant benefit for cetuximab (ie, the 95% CI excluded 1) and was comparable to the OS hazard ratio observed in the CRYSTAL study KRAS wild-type population (LNA assay) even after adjustment for potentially confounding baseline variables.ConclusionThese results support the utility of the therascreen assay for identifying patients who may benefit from cetuximab therapy for metastatic colorectal cancer.     

Concurrent Cetuximab-based bioradiotherapy versus Cisplatin-based Chemoradiotherapy in the Definitive Management of Favourable Biology Human Papillomavirus-associated Oropharyngeal Squamous Cell Carcinoma: Systematic Review and Meta-analysis

Replacing cisplatin with cetuximab concurrently during radiotherapy has been one of the strategies of treatment de-escalation in human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OPSCC). However, until recently, there were limited data on the efficacy and safety of such an approach. A systematic search of the literature was carried out to identify prospective randomised controlled trials comparing definitive cisplatin-based chemoradiotherapy (CT-RT) versus cetuximab-based bioradiotherapy (BRT) in HPV-positive OPSCC. Overall survival and locoregional control were primary outcomes of interest; rates of acute and late toxicities (≥grade 3) were secondary end points. Outcome data were aggregated using a random-effects model as per Cochrane methodology including risk of bias assessment and expressed as hazard ratio or risk ratio as appropriate with respective 95% confidence intervals. Data from five randomised controlled trials involving 1560 patients with HPV-positive OPSCC were aggregated in the meta-analysis. Cetuximab-based BRT was associated with a significantly increased risk of death (hazard ratio = 2.83, 95% confidence interval 1.22–6.57; P = 0.02) and locoregional relapse (hazard ratio = 2.78, 95% confidence interval 1.77–4.39; P < 0.0001) compared with cisplatin-based CT-RT. Cisplatin was associated with higher rates of acute ≥grade 3 toxicity in terms of acute kidney injury, dry mouth, febrile neutropenia, hearing impairment, nausea and vomiting, whereas dermatitis and acneiform rash were more common with cetuximab. There were no significant differences in overall rates of late ≥grade 3 toxicity (risk ratio = 0.63, 95% confidence interval = 0.36–1.10; P = 0.10). In conclusion, there is moderate-certainty evidence that cetuximab-based BRT leads to inferior efficacy outcomes compared with cisplatin-based CT-RT in the definitive curative-intent management of HPV-associated OPSCC.     

Comparative analysis of binding affinities to epidermal growth factor receptor of monoclonal antibodies nimotuzumab and cetuximab using different experimental animal models

Although pharmaco/toxicological studies have always been conducted in pharmacologically relevant species in which the test material is pharmacologically active, the very specificity of many biopharmaceuticals could present challenges in the identification of a relevant species for pharmaco/toxicological studies. Alternative approaches may improve the predictive value of preclinical assessments of species-specific biopharmaceuticals. This could lead to improved decision-making, reduce the number of experimental animals by eliminating non-relevant studies, and decrease the time and cost involved in the drug development process. As an alternative to utilizing traditional animal models, this study investigated the activity of human EGF and the anti-EGF receptor monoclonal antibodies nimotuzumab and cetuximab using the placenta microsomal fraction of different experimental animals. Ligand-receptor binding curves were obtained from the different experimental animal models, and binding constants were calculated based on the Scatchard plots. The constants for human and monkey EGF receptor expressed on the placental extract showed a K_a < 10⁻⁸ M, while rabbits, mice and rats showed a K_a > 10⁻⁸ M. The K_a values obtained from animal placentas show that Macaca fascicularis and Cercopitecus aethiops monkeys are relevant species for studying the pharmaco/toxicological properties of nimotuzumab and cetuximab.     

Overcoming cetuximab resistance in HNSCC: The role of AURKB and DUSP proteins

Unraveling the underlying mechanisms of cetuximab resistance in head and neck squamous cell carcinoma (HNSCC) is of major importance as many tumors remain non-responsive or become resistant. Our microarray results suggest that “resistant” cells still exhibit RAS–MAPK pathway signaling contributing to drug resistance, as witnessed by low expression of DUSP5 and DUSP6, negative regulators of ERK1/2, and increased expression of AURKB, a key regulator of mitosis. Therefore, interrupting the RAS–MAPK pathway by an ERK1/2 inhibitor (apigenin) or an AURKB inhibitor (barasertib) might be a new strategy for overcoming cetuximab resistance in HNSCC.