Early magnesium modifications as a surrogate marker of efficacy of cetuximab-based anticancer treatment in KRAS wild-type advanced colorectal cancer patients

Assessment of essential and toxic elemental concentrations in tumor and non-tumor tissues with risk of colorectal carcinoma in Pakistan

BACKGROUND

Colorectal tumor is a major cause of cancer morbidity and mortality both in USA and around the globe. Exposure to environmental toxicants such as toxic trace elements has been implicated in colorectal malignancy. However, data linking them to this cancer are generally lacking.

METHODS

Accordingly, the current study was to investigate the distribution, correlation and chemometric evaluation of 20 elements (Ca, Na, Mg, K, Zn, Fe, Ag, Co, Pb, Sn, Ni, Cr, Sr, Mn, Li, Se, Cd, Cu, Hg and As) in the tumor tissues (n = 147) and adjacent non tumor tissues (n = 147) of same colorectal patients which were analyzed by flame atomic absorption spectrophometry employing nitric acid-perchloric acid based wet digestion method.

RESULTS

On the average, Zn (p < 0.05), Ag (p < 0.001), Pb (p < 0.001), Ni (p < 0.01), Cr (p < 0.005) and Cd (p < 0.001) showed significantly higher levels in the tumor tissues compared with the non tumor tissues of patients, whereas mean levels of Ca (p < 0.01), Na (p < 0.05), Mg (p < 0.001), Fe (p < 0.001), Sn (p < 0.05) and Se (p < 0.01), were significantly elevated in the non tumor tissues than the tissues of tumor patients. Most of the elements revealed markedly disparities in their elemental levels based on food (vegetarian/nonvegetarian) habits and smoking (smoker/nonsmoker) habits of donor groups. The correlation study and multivariate statistical analyses demonstrated some significantly divergent associations and apportionment of the elements in the tumor tissues and non tumor tissues of donors. Noticeably, variations in the elemental levels were also noted for colorectal tumor types (lymphoma, carcinoids tumor and adenocarcinoma) and stages (I, II, III, & IV) in patients.

CONCLUSION

Overall, the study revealed that disproportions in essential and toxic elemental concentrations in the tissues are involved in pathogenesis of the malignancy. These findings provide the data base that helps to oncologist for diagnosis and prognosis of colorectal malignant patients.

Epidermal Growth Factor Receptor Inhibitor-Induced Hypomagnesaemia: Is There a Best Replacement Strategy?

Monoclonal antibodies targeting the epidermal growth factor receptor (EGFRI), such as cetuximab and panitumumab, are commonly used systemic therapies for advanced colorectal and head and neck cancers. Hypomagnesaemia is a common side effect of these therapies and occurs in up to 30% of patients. Interruption of EGFR signalling in the distal convoluted tubule leads to inactivation of the transcellular transporter transient receptor potential channel melastatin member 6 and increased renal magnesium excretion. This paper describes the incidence, risk factors, and the emerging management options for EGFRI-induced hypomagnesaemia.

Predictive and prognostic value of magnesium serum level in FOLFIRI plus cetuximab or bevacizumab treated patients with stage IV colorectal cancer: results from the FIRE-3 (AIO KRK-0306) study

Magnesium wasting is a frequent side effect of epidermal growth factor receptor (EGFR)-antibody treatment as magnesium-absorption mechanisms are dependent on EGFR signaling. EGFR-inhibition results in decreased renal reabsorption. There is evidence that hypomagnesemia during cetuximab treatment correlates with response. The prognostic role of hypomagnesemia during bevacizumab treatment has not been studied yet. Here, we evaluate the prognostic value of hypomagnesemia in patients with metastatic colorectal cancer treated with FOLFIRI plus cetuximab or bevacizumab as first-line therapy. A total of 391 of 752 patients of the firstline irinotecan study population had magnesium levels measured at baseline and for the first three cycles (6 weeks) of treatment. Of those, 240 had Rat Sarkoma wildtype tumors. Overall hypomagnesemia was more common in the cetuximab compared to the bevacizumab arm (80 vs. 43%, P < 0.005). During therapy, magnesium showed a time-dependent decrease to 80% of baseline in the cetuximab and to 89% in the bevacizumab arm. Whereas magnesium continued to decrease over time in the cetuximab-treated patients, it remained stable in the bevacizumab-treated. Overall response rate (ORR) was associated with higher magnesium at week 6 (20.9 vs. 79.1%, P = 0.041). Bevacizumab-treated patients with magnesium levels below the median value at week 6 had a significantly longer progression-free survival (PFS; 11.7 vs. 9.9 months, P = 0.034; hazard ratio 0.73) and a trend towards longer overall survival (OS) (29.6 vs. 23.2 months, P = 0.089; hazard ratio 0.77). Hypomagnesemia at predefined time points and magnesium nadir had no significant effect on ORR, OS and PFS in the cetuximab arm. Our data show different magnesium kinetics in patients with metastatic colorectal cancer treated with cetuximab or bevacizumab. For patients treated with cetuximab, hypomagnesemia did not have an impact on response and survival. Hypomagnesemia might have a prognostic value in bevacizumab treatment.

Imbalance of Mg Homeostasis as a Potential Biomarker in Colon Cancer

BACKGROUND

Increasing evidences support a correlation between magnesium (Mg) homeostasis and colorectal cancer (CRC). Nevertheless, the role of Mg and its transporters as diagnostic markers in CRC is still a matter of debate. In this study we combined X-ray Fluorescence Microscopy and databases information to investigate the possible correlation between Mg imbalance and CRC.

METHODS

CRC tissue samples and their non-tumoural counterpart from four patients were collected and analysed for total Mg level and distribution by X-Ray Fluorescence Microscopy. We also reviewed the scientific literature and the main tissue expression databases to collect data on Mg transporters expression in CRC.

RESULTS

We found a significantly higher content of total Mg in CRC samples when compared to non-tumoural tissues. Mg distribution was also impaired in CRC. Conversely, we evidenced an uncertain correlation between Mg transporters expression and colon malignancies.

DISCUSSION

Although further studies are necessary to determine the correlation between different cancer types and stages, this is the first report proposing the measurement of Mg tissue localisation as a marker in CRC. This study represents thus a proof-of-concept that paves the way for the design of a larger prospective investigation of Mg in CRC.

Magnesium Absorption in Intestinal Cells: Evidence of Cross-Talk between EGF and TRPM6 and Novel Implications for Cetuximab Therapy

Hypomagnesemia is very commonly observed in cancer patients, most frequently in association with therapy with cetuximab (CTX), a monoclonal antibody targeting the epithelial growth factor receptor (EGFR). CTX-induced hypomagnesemia has been ascribed to renal magnesium (Mg) wasting. Here, we sought to clarify whether CTX may also influence intestinal Mg absorption and if Mg supplementation may interfere with CTX activity. We used human colon carcinoma CaCo-2 cells as an in vitro model to study the mechanisms underlying Mg transport and CTX activity. Our findings demonstrate that TRPM6 is the key channel that mediates Mg influx in intestinal cells and that EGF stimulates such influx; consequently, CTX downregulates TRPM6-mediated Mg influx by interfering with EGF signaling. Moreover, we show that Mg supplementation does not modify either the CTX IC50 or CTX-dependent inhibition of ERK1/2 phosphorylation. Our results suggest that reduced Mg absorption in the intestine may contribute to the severe hypomagnesemia that occurs in CTX-treated patients, and Mg supplementation may represent a safe and effective nutritional intervention to restore Mg status without impairing the CTX efficacy.

Identifying optimal magnesium replenishment points based on risk of severe hypomagnesemia in colorectal cancer patients treated with cetuximab or panitumumab

PURPOSE

Cetuximab and panitumumab are monoclonal antibodies that target the epidermal growth factor receptor (EGFR). Treatment with cetuximab and panitumumab commonly causes hypomagnesemia, and optimal management of this adverse effect remains unclear. Here, we evaluated the optimal magnesium replacement points based on the risk of severe hypomagnesemia in colorectal cancer patients who received cetuximab or panitumumab.

METHODS

We retrospectively evaluated 184 patients who received cetuximab or panitumumab for colorectal cancer at Ogaki Municipal Hospital (Ogaki, Japan) between January 2010 and December 2019. Univariate analyses were conducted to evaluate the relationship between patient baseline characteristics and development of hypomagnesemia following cetuximab or panitumumab treatment. Variables that were significantly associated with hypomagnesemia in the univariate analyses as well as previously reported risk factors were entered into a multivariate logistic regression model.

RESULTS

The incidence of hypomagnesemia was associated with panitumumab treatment, pre-replenishment serum magnesium concentration, treatment duration, and treatment line. Severe hypomagnesemia post-cetuximab or panitumumab treatment was significantly associated with low baseline magnesium concentrations (< 1.8 mg/dL; odds ratio 18.100, 95% confidence interval 1.570-210.000; p = 0.020) and low serum magnesium concentrations during treatment (< 1.1 mg/dL; odds ratio 93.800, 95% confidence interval 3.510-2510.000; p = 0.007).

CONCLUSION

To minimize the risk of severe hypomagnesemia during anti-EGFR treatment, magnesium replenishment should be initiated in patients with pre-replenishment concentrations of < 1.8 mg/dL, preferably before reaching intra-treatment concentrations of < 1.1 mg/dL.

[Renal toxicities of targeted therapies in oncology]

The advent of new molecules oncology including targeted therapies, has resulted in improved patient survival over standard chemotherapy. The renal toxicities of these anticancer agents are more and more recognized and vary according to the targeted therapeutic target. This article reviews the renal toxicity associated with targeted anticancer therapies directed against Epidermal growth factor receptor, Human epidermal growth factor-2, B-rapidly accelerated fibrosarcoma, Mitogen-activated protein kinase, Anaplastic lymphoma kinase, Programmed cell death-1/programmed cell death ligand-1, Cytotoxic T lymphocyte antigen-4 and Vascular endothelial growth factor/receptor. The early diagnosis and management of these renal adverse events is essential for the clinician who cares for such patients.

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

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

Hypomagnesemia and Survival in Patients with Ovarian Cancer Who Received Chemotherapy with Carboplatin

BACKGROUND

Hypomagnesemia is a known side effect of several antineoplastic agents, but its impact on outcomes of patients with cancer is not well understood. We examined whether magnesium abnormalities affect survival in patients with ovarian cancer who receive chemotherapy containing carboplatin.

MATERIALS AND METHODS

We included patients with advanced ovarian cancer who had undergone surgery and chemotherapy between January 1, 2004, and December 31, 2014, at our institution. Inclusion criteria were age 18 years or older, pathology of high-grade serous carcinoma, first treatment (surgery or chemotherapy) within 60 days of diagnosis, and chemotherapy containing carboplatin. The final cohort consisted of 229 patients. Vital signs and laboratory tests were recorded at baseline and during the treatment course. The associations between magnesium abnormalities (and other clinical characteristics) and survival were analyzed.

RESULTS

The median patient age was 64 years. Higher baseline heart rate (beats per minute; hazard ratio [HR] = 1.02, p = .002) and greater frequency of hypomagnesemia during the treatment course (HR = 1.05, p = .002) were significantly associated with shorter survival independent of completeness of tumor reduction (HR = 1.60, p = .02), and International Federation of Gynecology and Obstetrics stage (HR = 1.63, p = .01).

CONCLUSION

Baseline heart rate and the frequency of hypomagnesemia episodes during treatment are prognostic of survival for patients with advanced ovarian cancer receiving carboplatin-containing chemotherapy and tumor reductive surgery. Future research is needed for strategies to detect and prevent hypomagnesemia in this patient population.

IMPLICATIONS FOR PRACTICE

Despite standard laboratory tests and intravenous magnesium replacement prior to each cycle of chemotherapy, hypomagnesemia remains a common side effect of platinum-based chemotherapy. This study revealed that frequent occurrence of hypomagnesemia during the course of treatment including carboplatin-containing chemotherapy and tumor reductive surgery was strongly predictive of shorter survival in patients with advanced ovarian cancer. Strategies to effectively mitigate hypomagnesemia, such as more frequent detection, dietary recommendations, and timely replacement, should be considered in the overall cancer treatment plan for these patients.

Adverse kidney effects of epidermal growth factor receptor inhibitors

The epidermal growth factor receptor (EGFR) is implicated in various malignancies. The past decade has seen the development and widespread use of EGFR inhibitors for the successful treatment of such cancers. Available EGFR inhibitors include small molecule tyrosine-kinase inhibitors and monoclonal antibodies. Class-related renal adverse events result in dual toxicity including tubular/electrolyte disorders and glomerulopathies. Tubular injury is common and mainly due to monoclonal antibodies while glomerulopathy is rare and related to various anti-EGFR agents. The exact pathogenesis of anti-EGFR agents associated with kidney disorders remains to be elucidated.

Chemotherapy in patient with colon cancer after renal transplantation: A case report with literature review

RATIONALE

Experience of pharmacotherapy in posttransplantation colorectal cancer (CRC) patients is inadequate.

PATIENT CONCERNS

A Chinese man had right renal transplantation and began immunosuppressive treatment at the age of 31 in 2009. He was diagnosed with colon cancer and underwent anterior resection in 2014. He was diagnosed with metastatic colon carcinoma by abdomen computed tomography (CT) and positron emission tomography-computed tomography in April 2017.

DIAGNOSIS

Metastatic colon carcinoma in posttransplantation patient.

INTERVENTIONS

Three cycles of FLOFOX (5-fluorouracil and leucovorin and oxaliplatin) chemotherapy were given since April 2017.

OUTCOMES

Plasma concentrations of immunosuppressant and kidney function were within normal during the chemotherapy. Abdomen CT revealed the progress of colon cancer at the end of the third course of chemotherapy.

LESSONS

A few cases about monochemotherapy of posttransplantation CRC have been reported, whereas experience of doublet chemotherapy was currently unavailable. We shared the experience of FOLFOX in a patient with posttransplantation colon cancer. Neither of incompatibility with immunosuppressant nor serious adverse drug reaction was observed. It provides evidence for the pharmacotherapy of posttransplantation CRC.

Hypomagnesemia and clinical benefits of anti-EGFR monoclonal antibodies in wild-type KRAS metastatic colorectal cancer: a systematic review and meta-analysis

Hypomagnesemia is a recognized side-effect of cetuximab- or panitumumab-based chemotherapy for metastatic colorectal cancer (mCRC). The clinical relevance of hypomagnesemia is under debate. Thus, a systematic review and meta-analysis of retrospective studies and randomized clinical trials (RCTs) comparing hypomagnesemia with normal magnesium levels in wild-type KRAS mCRC was performed. One RCT, two retrospective studies, and two American Society of Clinical Oncology (ASCO) and European Society for Medical Oncology (ESMO) conference presentations from phase III RCTs involving 1723 patients were included in this study. Patients with hypomagnesemia demonstrated better progression-free survival (PFS) (Hazard ratio [HR]: 0.64; 95% confidence interval [CI]: 0.47–0.88), overall survival (OS) (HR: 0.72; 95% CI: 0.53–0.92), and objective response rate (ORR) (Risk ratio [RR]: 1.81; 95% confidence interval [CI]: 1.30–2.52). By subgroup analysis, frontline, later lines or combination therapy with hypomagnesemia were associated with PFS benefits (HR: 0.78; 95% CI: 0.62–0.98; HR: 0.60; 95% CI: 0.40–0.90; HR: 0.62; 95% CI: 0.41–0.94, respectively). In patients with wild-type KRAS mCRC, hypomagnesemia is associated with better clinical benefits of PFS, OS and ORR when treated with cetuximab- or panitumumab-based chemotherapy. Future clinical trials should corroborate its predictive role.

Anti-EGFR monoclonal antibody panitumumab for the treatment of patients with metastatic colorectal cancer: an overview of current practice and future perspectives

INTRODUCTION

Targeted agents alone or in combination with chemotherapy are current standard of treatment for metastatic colorectal cancer (mCRC). Panitumumab is a fully human monoclonal antibody which inhibits the epidermal growth factor receptor (EGFR). It is currently approved in combination with chemotherapy in first- and second-line and as a monotherapy in chemorefractory patients. RAS gene mutations confer resistance to anti-EGFR agents; thus, panitumumab is restricted to the treatment of RAS wild-type (WT) tumors. Areas covered: This review explores the available data on panitumumab and presents new perspectives on predictive markers of anti-EGFR efficacy including primary tumor sidedness and BRAF mutations. Other details covered include panitumumab's mechanism of action, pharmacokinetics, pharmacodynamics and safety aspects of the therapy as well as mechanisms of secondary resistance and future prospects of treatment in different settings. Expert opinion: Panitumumab has significantly added to the treatment armamentarium for RAS WT mCRC. The effort spent in identifying predictive biomarkers of panitumumab efficacy has been of pivotal importance to development of the molecular selection of patients with mCRC. Primary and secondary resistance, however, still represent important issues. Novel strategies to overcome those issues are currently underway with promising results which highlight the potential use of panitumumab in combination with other targeted agents in the future.

Multicenter Phase II Study of Panitumumab in Platinum Pretreated, Advanced Head and Neck Squamous Cell Cancer

Lessons Learned.

Panitumumab shows activity in terms of disease control rate and preventing disease progression but not for tumor shrinkage in head and neck squamous cell cancer for second‐line treatment. Epidermal growth factor receptor (EGFR) copy number gain, a property of tumor cells that theoretically could identify patients more likely to experience disease response, was common among patients having disease control.

Our trial, given the lower toxicity with an every‐2‐week schedule, provides guidance for future trials, for example, in combinations of immune therapies and anti‐EGFR‐antibodies.

Background.

The objective of this study was to investigate the efficacy and safety of panitumumab (anti‐epidermal growth factor receptor [EGFR] antibody) given as a single agent in platinum‐pretreated head and neck squamous cell cancer (HNSCC).

Methods.

Patients with advanced HNSCC previously treated with platinum‐containing therapy were included. Panitumumab was administered intravenously every 2 weeks at a dose of 6 mg/kg. Primary endpoint was overall response rate (ORR) according to Response Evaluation Criteria In Solid Tumors (RECIST) version 1.1; secondary endpoints were progression‐free survival (PFS) and safety. A Simon's two‐step design was chosen; 4 partial remissions (PR) in the first 32 patients were required for continuing to step two. An exploratory biomarker analysis was performed.

Results.

Thirty‐three patients were enrolled. Two patients obtained a PR for an ORR of 6%, and 15 (45%) showed stable disease (SD) for at least 2 months, resulting in a 51% disease control rate. Median PFS was 2.6 months (95% confidence interval [CI]: 1.7–3.7), while median OS was 9.7 months (95% CI: 6.3–17.2). The most frequent adverse drug reactions were cutaneous rash (64%) and hypomagnesemia (55%). Overall, 30% of patients experienced grade 3/4 adverse events. No infusion‐related reactions occurred. EGFR copy number gain (CNG) was more frequent in patients who benefitted from panitumumab. Two uncommon KRAS mutations (G48E, T50I) and 3 canonical PIK3CA mutations (all E545K) were detected. High‐risk HPV16 was found in 10 patients and EGFR CNG in 13 treated patients. EGFR CNG seems to be more frequent in individuals with at least SD compared with patients with progressive disease (59% vs. 30%). PFS for patients with EGFR CNG was 4.6 months (95% CI: 1.0–9.2 months) and 1.9 months (95% CI: 1.0–3.2 months) for patients without CNG (p = .02).

Conclusion.

Panitumumab monotherapy in pretreated HNSCC patients was well tolerated but moderately active. We observed a considerable disease control rate. Future strategies with this agent comprise right patient selection through the identification of reliable biomarkers and gene signatures predicting response and, considering good tolerability and convenience, combination strategies with novel agents and immune therapeutic agents.

Activity of weekly paclitaxel-cetuximab chemotherapy in unselected patients with recurrent/metastatic head and neck squamous cell carcinoma: prognostic factors

BACKGROUND

Standard treatment for recurrent/metastatic head and neck squamous cell carcinoma (RM-SCCHN) is based in on platinum and cetuximab combination therapy. Unfortunately, not all patients are candidates to receive platinum-based treatment, because of different conditions as comorbidity and poor performance status. Weekly paclitaxel and cetuximab (WPC) is an active therapeutic alternative, based on a phase II study, with less toxicity. Our main objective is to confirm its activity in unselected patients, mostly unfit for aggressive therapies, analysing also some clinically relevant prognostic factors (PFs).

METHODS

Retrospective data was collected for RM-SCCHN patients, treated at our institution between January 2008 and July 2014 with weekly paclitaxel (80 mg/m²) and cetuximab (400/250 mg/m²).

RESULTS

148 patients were treated. The objective response rate (OR) was as follows: 13 patients (8.78%) complete response (CR); 57 patients (38.51%) partial response (PR) and 30 patients (20.3%) stable disease (SD). Median overall survival (OS) was 10 months (95% CI 8.31-11.69) and median progression free survival (PFS) was 7 months (95% CI 5.88-8.12). Response to treatment showed independent prognosis relevance as PF in multivariate analysis for PFS and OS. Furthermore, decline in serum magnesium during the treatment was also an independent PF for OS.

CONCLUSIONS

WPC activity was confirmed as a useful therapy on real-life unselected RM-SCCHN patients, with similar benefit to that obtained in the phase II study, and comparable to platinum and cetuximab based treatment, confirming its value in unfit patients. In addition to treatment response, a change in serum magnesium values during treatment was proved as independent PF on OS.

Final results and outcomes by prior bevacizumab exposure, skin toxicity, and hypomagnesaemia from ASPECCT: randomized phase 3 non-inferiority study of panitumumab versus cetuximab in chemorefractory wild-type KRAS exon 2 metastatic colorectal cancer

PURPOSE

The primary analysis of the ASPECCT study demonstrated that panitumumab was non-inferior to cetuximab for overall survival (OS) in patients with chemotherapy-refractory wild-type KRAS exon 2 metastatic colorectal cancer (mCRC). Here, we report the final analysis results of ASPECCT.

PATIENTS AND METHODS

Patients with wild-type KRAS exon 2 mCRC who progressed on or were intolerant to irinotecan- or oxaliplatin-based chemotherapy were randomised to receive panitumumab 6 mg/kg once every 2 weeks or cetuximab (400 mg/m²) followed by 250 mg/m² weekly. The primary end-point was OS assessed for non-inferiority. Patients were followed for survival for 24 months after the last patient was randomised and a final analysis was conducted. No formal hypothesis testing was done. Post hoc analyses of outcomes by prior bevacizumab exposure, worst-grade skin toxicity (0-1 versus 2-4) and worst-grade hypomagnesaemia (0 versus 1-4) were conducted.

RESULTS

Nine hundred ninety-nine patients were randomised and received ≥1 treatment dose (panitumumab, n = 499; cetuximab, n = 500). Median OS was 10.2 months with panitumumab versus 9.9 months with cetuximab (hazard ratio = 0.94; 95% confidence interval = 0.82-1.07). Median progression-free survival was 4.2 months with panitumumab and 4.4 months with cetuximab (hazard ratio = 0.98; 95% confidence interval = 0.87-1.12). Longer OS was observed for patients with increased skin toxicity and with hypomagnesaemia in both arms. Furthermore, OS was longer for patients with prior bevacizumab exposure treated with panitumumab than with cetuximab. The observed safety profiles were consistent with previous studies.

CONCLUSION

Consistent with the primary analysis, the final analysis of ASPECCT showed panitumumab was non-inferior to cetuximab for OS for patients with chemotherapy-refractory, wild-type KRAS exon 2 mCRC.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT01001377.

Incidence and Risk Factors of Hypomagnesemia in Head and Neck Cancer Patients Treated with Cetuximab

Background

Hypomagnesemia is a common adverse event during cetuximab (Cmab) treatment. However, few reports have investigated the incidence and risk factors of hypomagnesemia in head and neck cancer patients treated with Cmab.

Methods

We retrospectively reviewed 131 head and neck cancer patients who received Cmab-containing therapy. Main eligibility criteria were ≥3 Cmab administrations, no prior EGFR-directed therapy, and no prophylactic Mg supplementation.

Results

Median baseline serum Mg level and number of Cmab administrations were 2.2 mg/dl and 8, respectively. Overall incidence of hypomagnesemia was 50.4% (grade 1, 46.6%; grade 2, 3.1%; grade 3, 0%; and grade 4, 0.8%) and differed between patients treated with palliative chemotherapy and bioradiation (Cmab and radiation) (63 versus 24%; P < 0.01). Independent risk factors were low baseline serum Mg [odds ratio (OR) 161.988, 95% confidence interval (CI) 9.436–2780.895], ≥7 Cmab administrations (OR 3.56, 95% CI 1.16–13.98), and concurrent administration of platinum (cisplatin; OR 23.695, 95% CI 5.219–107.574, carboplatin; OR 5.487, 95% CI 1.831–16.439). Respective incidence of hypomagnesemia in patients in high- (concurrent platinum and ≥7 Cmab administrations) and low-risk (no concurrent platinum and <7 Cmab administrations) groups was 66.0 and 6.6% (P < 0.001, OR 28.0).

Conclusion

Cmab is associated with a significant risk of hypomagnesemia in patients with head and neck cancer with longer term administration and concurrent platinum therapy. High-risk patients should be treated with particular care.

Hypomagnesemia is a reliable predictor for efficacy of anti-EGFR monoclonal antibody used in combination with first-line chemotherapy for metastatic colorectal cancer

PURPOSE

Anti-EGFR monoclonal antibody is effective for KRAS wild-type metastatic colorectal cancer (mCRC), but frequently causes several adverse reactions, including hypomagnesemia and skin disorders. The present study was designed to investigate the relationship between the incidence of adverse reactions and therapeutic effects in mCRC patients receiving anti-EGFR monoclonal antibody in combination with first-line chemotherapy.

METHODS

Forty-three mCRC patients who received cetuximab or panitumumab between April 2012 and December 2015 were the subjects of the present study. All patients were pretreated with oral minocycline in combination with skin treatment using moisturizer for prevention of skin rash. Hypomagnesemia and acneiform rash were graded according to the Common Terminology Criteria for Adverse Events, version 3.0. Overall response rate (ORR) and time to treatment failure (TTF) were compared between patients with and without these adverse events.

RESULTS

The incidence rates of hypomagnesemia and acneiform rash were 32.6 % (grade 1: 20.9 %, grade 2: 11.6 %) and 93.0 % (grade 1: 41.9 %, grade 2: 41.9 %, grade 3: 9.3 %), respectively. ORR was significantly higher in patients with hypomagnesemia than in those without it (71.4 vs 34.5 %, P = 0.048). Median TTF tended to be longer, though not significantly, in patients with hypomagnesemia than in those without it. However, no significant difference in both ORR and median TTF was observed between patients with and without acneiform rash.

CONCLUSION

Hypomagnesemia may become a predicting factor for therapeutic effects of anti-EGFR monoclonal antibody in mCRC patients.

Pharmacokinetic and pharmacodynamic evaluation of panitumumab in the treatment of colorectal cancer

INTRODUCTION

Integration of targeted therapy and additional chemotherapy options has improved median overall survival (OS) in patients with unresectable metastatic colorectal cancer (mCRC). Cetuximab and panitumumab are examples of targeted therapies, specifically against the epidermal growth factor receptor (EGFR). This review focuses on Panitumumab, a fully human IgG2 monoclonal antibody, which inhibits key oncogenic downstream cell signalling pathways. Panitumumab and cetuximab have improved tumour response rate, progression-free survival, and OS in mCRC patients in whom the RAS (Rat Sarcoma) gene is of Wild Type (WT) status.

AREAS COVERED

The EGFR signalling pathway and preclinical, Phase I and Phase II clinical studies on the pharmacokinetic, pharmacodynamic and safety evaluation of panitumumab are presented. Phase III studies utilising panitumumab in the first, second and third line setting in mCRC are also described.

EXPERT OPINION

Panitumumab exhibits excellent pharmacokinetics and pharmacodynamics by way of uncomplicated dosing, non-existent drug interactions, minimal infusion reactions and manageable side effects, making it a suitable target for combination treatments. However, innate and acquired resistances are still obstacles. To overcome this, experimented strategies are ongoing, particularly in patients with Her-2 and BRAF gene alterations. Novel biomarkers to improve patient selection and second-generation targeted antibodies are in development.

Assessment of frequency and severity of hypomagnesemia in patients with metastatic colorectal cancer treated with cetuximab, with a review of the literature

Currently, there are a few systemic treatment options for patients with metastatic colorectal cancer (mCRC). Targeted therapy used in this setting includes the use of monoclonal antibodies, such as cetuximab or panitumumab, directed against epidermal growth factor receptor. The aim of the present study was to estimate the frequency and severity of hypomagnesemia among patients with mCRC treated with cetuximab. The data from the Department of Clinical Oncology, University Hospital of Krakow (Krakow, Poland), concerning 52 patients treated between 2009 and 2013 were collected. Of these, 27 patients fulfilled the inclusion criteria to enter this retrospective study. The National Cancer Institute Common Terminology Criteria for Adverse Events version 4.0 were used to grade the level of hypomagnesemia. In total, 29.6% of all patients experienced hypomagnesemia during treatment, and the majority of cases were grade 1 (22.2%). There was no statistically significant correlation between magnesium (Mg) level and patient age, duration of treatment, localization of primary tumor or metastases, and the number of metastases. However, there was an upward trend in a logistic regression model showing that the risk of developing hypomagnesemia increases with age. Hypomagnesemia is a frequent problem among mCRC patients receiving cetuximab. It is essential to introduce guidelines regarding the monitoring of the Mg level and its supplementation in this group of patients.

Prognostic and predictive response factors in colorectal cancer patients: Between hope and reality

Colorectal cancer (CRC) represents one of the most commonly diagnosed cancers worldwide. It is the second leading cause of cancer death in Western Countries. In the last decade the survival of patients with metastatic CRC has improved dramatically. Due to the advent of new drugs (irinotecan and oxaliplatin) and target therapies (i.e., bevacizumab, cetuximab and panitumab), the median overall survival has risen from about 12 mo in the mid nineties to 30 mo recently. Many questions needing of right collocations and more clearness still exist regarding the prognostic factors and the predictive factors of response to therapy. Despite advances in dosing and scheduling of chemotherapy in both adjuvant and advanced settings, and a greater emphasis on early detection, the outlook still remains poor for most patients. Molecular analyses have shown that the natural history of all CRCs is not the same. Individual patients with same stage tumours may have different long term prognosis and response to therapy. In addition, some prognostic variables are likely to be more important than others. Here we review the role of prognostic factors and predictive factors according to the recently published English literature.

Early skin toxicity predicts better outcomes, and early tumor shrinkage predicts better response after cetuximab treatment in advanced colorectal cancer

Cetuximab-containing treatments for metastatic colorectal cancer have been shown to have higher overall response rates and longer progression-free and overall survival than other systemic therapies. Cetuximab-related manifestations, including severe skin toxicity and early tumor shrinkage, have been shown to be predictors of response to cetuximab. We hypothesized that early skin toxicity is a predictor of response and better outcomes in patients with advanced colorectal carcinoma. We retrospectively evaluated 62 patients with colorectal adenocarcinoma who had unresectable tumors and were treated with cetuximab in our institution. Skin toxicity grade was evaluated on each treatment day. Tumor size was evaluated using computed tomography prior to treatment and 4-8 weeks after the start of treatment with cetuximab.Patients with early tumor shrinkage after starting treatment with cetuximab had a significantly higher overall response rate (P = 0.0001). Patients with early skin toxicity showed significantly longer overall survival (P = 0.0305), and patients with higher skin toxicity grades had longer progression-free survival (P = 0.0168).We have shown that early tumor shrinkage, early onset of skin toxicity, and high skin toxicity grade are predictors of treatment efficacy and/or outcome in patients with advanced colorectal carcinoma treated with cetuximab.

Panitumumab safety for treating colorectal cancer

INTRODUCTION

Panitumumab is a human IgG2 mAb against the EGFR, inhibiting tumor cell proliferation, survival and angiogenesis. It has demonstrated clinical efficacy in metastatic colorectal cancer (CRC) in combination with chemotherapy in first- and second-line settings and as monotherapy in third-line setting. Recently, mutations in the RAS genes have been shown to be predictive of lack of efficacy, panitumumab should be restricted to patients with RAS wild-type (wt) tumors.

AREAS COVERED

This review focuses on main efficacy results of panitumumab in metastatic CRC in first-, second- and third-line settings in combination with chemotherapy or as monotherapy. Additionally, we have covered safety aspects of this agent in these indications, especially in K-RAS and all RAS wt patients. These safety aspects refer to the most common toxicities (i.e., acne-like skin rash, diarrhea and hypomagnesaemia).

EXPERT OPINION

Panitumumab adds to the armamentarium of effective agents in the treatment of metastatic CRC. Due to its human origin, panitumumab is a well-tolerated agent with low rates of infusional reactions. Skin toxicity is frequent and should be pre-emptively treated. Other common toxicities related to panitumumab treatment, such as diarrhea and hypomagnesaemia, should be closely monitored to ensure early treatment or substitution.

Epidermal growth factor receptor: pathway, therapies, and pipeline

BACKGROUND

The epidermal growth factor receptor (EGFR) pathway is important in tumor growth, survival, and metastasis and is now the target of several therapeutic agents.

OBJECTIVES

This paper seeks to review the EGFR pathway, the study and use of EGFR-directed agents in non-small-cell lung cancer (NSCLC) and colorectal cancer (CRC), and related new drug development.

METHODS

PubMed was searched for English-language articles by MeSH and title terms of EGFR published from 2006 to 2013, using the limits of clinical trials as well as reviews. Reference lists were assessed for relevant articles, and guidelines were searched. Clinicaltrials.gov and meeting abstracts were queried for investigational agents. Eligible papers included those concerning EGFR biology, NSCLC or CRC studies involving EGFR-directed agents, and/or investigational drugs targeting EGFR and/or associated pathways.

RESULTS

The activity of oral tyrosine kinase inhibitors (TKIs) against EGFR has improved survival in NSCLC, and these agents particularly effective in cancers with an EGFR mutation. Resistance to TKIs is most commonly related to a second, T790M, mutation, or to MET amplification, with newer agents directed against these mechanisms. Conversely, in CRC, TKIs have been ineffective, whereas monoclonal antibodies have improved survival. Both primary and secondary KRAS mutations in CRC abrogate mAb effectiveness. Several targets, including MET, BRAF, and PI3K, may serve useful in combination with anti-EGFR drugs.

CONCLUSIONS

Exploitation of EGFR-directed therapies has offered improvement in survival and quality of life in NSCLC and CRC. New therapies directed at EGFR may offer further improvements. However, resistance mechanisms suggest that combination therapies or multitargeted agents will be crucial in making significant future advances.

A 3-weekly schedule of irinotecan and panitumumab for wild-type KRAS metastatic colorectal cancer

SUMMARY 

Aim: We investigated the combination of irinotecan and panitumumab as a 3-weekly schedule in patients with wild-type KRAS metastatic colorectal cancer, who had progressed after standard chemotherapy. Material & methods: Patients received concomitant irinotecan (350 mg/m2) and panitumumab (9 mg/kg) once every 3 weeks. The primary end point was response rate. Secondary end points included progression-free survival (PFS), overall survival (OS) and translational research. Results: Inclusion was stopped early owing to lack of efficacy (n = 31). The response rate was 16%, median PFS and OS was 2.0 months (95% CI: 1.9–4.0) and 7.8 months (95% CI: 4.6–8.8), respectively. The most commonly encountered adverse event was skin rash (84% any grade). Pretreatment cell-free DNA levels were significantly related to disease control (p = 0.04), PFS (p = 0.04) and OS (p = 0.002), respectively. Conclusion: The present treatment regimen was less effective than expected and is not recommended. The clinical importance of cell-free DNA deserves further research.

Nephrotoxicity of recent anti-cancer agents

Cancer patients may develop a variety of kidney lesions that impair not only their immediate survival but also limit the adequate treatment of the underlying malignant process. This review summarizes the nephrotoxic potential of some of the most recently developed anti-cancer drugs, focusing on those interfering with the vascular endothelial growth factor and epidermal growth factor receptor pathways and mammalian target of rapamycin inhibitors. Thrombotic microangiopathy (haemolytic-uraemic syndrome), proteinuria, hypertension and magnesium depletion are the most common side effects. Also the risk for developing acute kidney injury in patients with advanced prostate cancer undergoing androgen deprivation therapy is discussed.

Personalized treatment for advanced colorectal cancer: KRAS and beyond

Targeted therapies have improved the survival of patients with advanced colorectal cancer (CRC). However, further improvements in patient outcomes may be gained by the development of predictive biomarkers in order to select individuals who are most likely to benefit from treatment, thus personalizing treatment. Using the epidermal growth-factor receptor (EGFR) pathway, we discuss the existing and potential predictive biomarkers in clinical development for use with EGFR-targeted agents in metastatic CRC. The data and technological issues surrounding such biomarkers as expression of EGFR or its family members or ligands, KRAS-, NRAS-, and BRAF-mutation status, PI3K/PTEN expression, and imaging and clinical biomarkers, such as rash and hypomagnesemia, are summarized. Although the discovery of KRAS mutations has improved patient selection for EGFR-targeted treatments, further biomarkers are required, especially for those patients who exhibit KRAS mutations rather than the wild-type gene.

Nonlinear association between magnesium intake and the risk of colorectal cancer

OBJECTIVES

The association between dietary magnesium intake and the risk of colorectal cancer has been examined by many prospective studies, but remains controversial because of inconsistent results. We aimed to carry out a meta-analysis to investigate this.

MATERIALS AND METHODS

We assessed this association with categorical and dose-response meta-analysis of data from prospective cohort studies. Relevant studies were identified by searching MEDLINE, EMBASE, and OVID for studies published before 9 June 2012, with no restrictions. Relative risks (RRs) and 95% confidence intervals (CIs) for the highest versus lowest and dose-response association were estimated using random-effects models. Heterogeneity and publication bias was investigated, and subgroup, sensitivity, and meta-regression analyses were carried out.

RESULTS

The analysis included 333 510 participants with 7435 colorectal cancers from seven prospective cohort studies. The summary RR for the highest versus the lowest intake of dietary magnesium was 0.81 (95% CI: 0.70-0.92) for colorectal cancer, 0.76 (95% CI: 0.64-0.88) for colon cancer, and 0.82 (95% CI: 0.58-1.06) for rectal cancer. For men and women, the pooled RR was 0.76 (95% CI: 0.51-1.01) and 0.81 (95% CI: 0.68-0.94), respectively. Significant inverse associations of colorectal cancer and dietary magnesium emerged in nonlinear models (p nonlinearity=0.03). The greatest risk reduction was observed when dietary magnesium intake increased from very low levels.

CONCLUSION

Dietary magnesium intake has a statistically significant nonlinear inverse association with the risk of colorectal cancer. The greatest reduction for magnesium intake is 200-270 mg/day. Whether the association is causal or because of confounding warrants further investigation.

Magnesium monitoring practice in monoclonal anti-epidermal growth factor receptor antibodies therapy

WHAT IS KNOWN AND OBJECTIVE

It is now estimated that about 5% of cetuximab-treated patients and about 3% of panitumumab-treated patients will develop grade 3-4 hypomagnesemia. The aim of this study was to assess the extent of magnesium monitoring in patients treated with epidermal growth factor receptor (EGFR)-targeting antibodies and to estimate the incidence of hypomagnesemia in these patients at our institution.

METHODS

A 2-year retrospective study was carried out. At least four doses of weekly cetuximab or two doses of bi-weekly panitumumab were required for inclusion. Serum magnesium profiles were reviewed from 1 month before treatment until 3 months after treatment discontinuation, and patients with <2 determinations were excluded.

RESULTS AND DISCUSSION

Two hundred and one patients received at least one dose of EGFR-targeting antibodies, but only 68 met the inclusion criteria. Seventy patients had <2 magnesium determinations. The overall hypomagnesemia was 58·82% (40 of 68 patients), with a 4·41% grade 3 hypomagnesemia (three of 68 patients). No grade 4 hypomagnesemia was detected.

WHAT IS NEW AND CONCLUSION

There is a lack of magnesium monitoring in these patients. Serum magnesium determinations should be done every 4-8 weeks in patients treated with EGFR-targeting antibodies, as it is a useful surrogate marker for both toxicity and efficacy.

Association of hypomagnesemia with inferior survival in a phase III, randomized study of cetuximab plus best supportive care versus best supportive care alone: NCIC CTG/AGITG CO.17

BACKGROUND

Cetuximab-induced hypomagnesemia has been associated with improved clinical outcomes in advanced colorectal cancer (CRC). We explored this relationship from a randomized clinical trial of cetuximab plus best supportive care (BSC) versus BSC alone in patients with pretreated advanced CRC.

PATIENTS AND METHODS

Day 28 hypomagnesemia grade (0 versus ≥1) and percent reduction (<20% versus ≥20%) of Mg from baseline was correlated with outcome.

RESULTS

The median percentage Mg reduction at day 28 was 10% (-42.4% to 63.0%) for cetuximab (N = 260) versus 0% (-21.1% to 25%) for BSC (N = 251) [P < 0.0001]. Grade ≥1 hypomagnesemia and ≥20% reduction from baseline at day 28 were associated with worse overall survival (OS) [hazard ratio, HR 1.61 (95% CI 1.12-2.33), P = 0.01 and 2.08 (95% CI 1.32-3.29), P = 0.002, respectively] in multivariate analysis including grade of rash (0-1 versus 2+). Dyspnea (grade ≥3) was more common in patients with ≥20% versus < 20% Mg reduction (68% versus 45%; P = 0.02) and grade 3/4 anorexia were higher in patients with grade ≥1 hypomagnesemia (81% versus 63%; P = 0.02).

CONCLUSIONS

In contrast to prior reports, cetuximab-induced hypomagnesemia was associated with poor OS, even after adjustment for grade of rash.

Cetuximab in metastatic colorectal cancer

Management of metastatic colorectal cancer has evolved in the last 10 years, with the availability of targeted therapies resulting in improvement in quality of life and overall survival. Cetuximab is a chimeric monoclonal antibody that binds to the EGF receptor, and the net effects are inhibition of tumor growth, invasion, angiogenesis and metastasis. Cetuximab binding to the EGF receptor is also known to augment the effects of chemotherapy and radiotherapy. Only tumors expressing wild-type KRAS respond to cetuximab and improvements in progression-free survival and overall survival are seen, whereas patients with mutant KRAS are considered to be resistant. Cetuximab is currently available worldwide for use as monotherapy or in combination with chemotherapy in first-, second- or third-line settings in metastatic colorectal cancer patients with wild-type KRAS.

Magnesium and its transporters in cancer: a novel paradigm in tumour development

The relationship between magnesium and cancer is not as simple as could be assumed from the well-established requirement of magnesium for cell proliferation. Basic and pre-clinical studies indicate that magnesium deficiency can have both anti- and pro-tumour effects. In the present review, we briefly outline the new findings on the role of magnesium in angiogenesis and metastatization, and focus on the relationship between tumour cell proliferation and metabolic reprogramming, discussing how magnesium and its transporters are involved in these processes. The role of magnesium in cancer is also critically examined with regard to mitochondrial function, apoptosis and resistance to treatment. Finally, we bring together the latest experimental evidence indicating that alteration in the expression and/or activity of magnesium channels is a frequent finding in cancer cells and human tumour tissues examined to date, and we discuss the potential implications for developing novel diagnostic and therapeutic strategies.

Prognostic and predictive biomarkers for epidermal growth factor receptor-targeted therapy in colorectal cancer: beyond KRAS mutations

The advent of the epidermal growth factor receptor (EGFR)-targeted monoclonal antibodies (mAbs), cetuximab and panitumumab has expanded the range of treatment options for metastatic colorectal cancer (CRC). Despite these agents have paved the way to individualized therapy, our understanding why some patients respond to treatment whereas others do not remain poor. The realization that detection of positive EGFR expression by IHC does not reliably predict clinical outcome of EGFR-targeted treatment has led to an intense search for alternative predictive biomarkers. Data derived from multiple phase III trials have indicated that KRAS mutations can be considered a highly specific negative biomarker of benefit to anti-EGFR mAbs. Oncologists are now facing emerging issues in the treatment of metastatic CRC, including the identification of additional genetic determinants of primary resistance to EGFR-targeted therapy for further improving selection of patients, the explanation of rare cases of patients carrying KRAS-mutated tumours who have been reported to respond to cetuximab and panitumumab and the discovery of mechanisms of secondary resistance to EGFR-targeted therapy. Current data suggest that, together with KRAS mutations, the evaluation of EGFR gene copy number (GCN), BRAF, NRAS, PIK3CA mutations or loss of PTEN expression could also be useful for selecting patients with reduced chance to benefit from anti-EGFR mAbs. This review aims to provide an updated of the most recent data on predictive and prognostic biomarkers within the EGFR pathway, the challenges this emerging field presents and the future role of these molecular markers in CRC treatment.

Risk of anti-EGFR monoclonal antibody-related hypomagnesemia: systematic review and pooled analysis of randomized studies

INTRODUCTION

The typical class side effect of anti-epidermal growth factor receptor (EGFR) monoclonal antibodies (panitumumab and cetuximab) is a cutaneous maculopapular rash, although hypomagnesemia is also described to be a frequent adverse event. The purpose of our meta-analysis is to evaluate the frequency and the relative risk of hypomagnesemia in patients treated with cetuximab or panitumumab in randomized trials.

AREA COVERED

Eligible studies included prospective randomized Phase III controlled trials in which cetuximab or panitumumab were compared with standard anti-neoplastic therapy or best supportive care. Summary incidence rates and relative risks with 95% confidence intervals were calculated.

EXPERT OPINION

The overall incidence of hypomagnesemia was 17% among the patients who received the treatment, whose risk of developing hypomagnesemia turned out to be significantly increased compared with the patients treated with control medication, with an overall relative risk of 5.83 (p < 0.00001), where 3.87 refers to cetuximab and 12.55 to panitumumab. The addition of anti-EGFR monoclonal antibodies to standard anticancer therapy showed a significantly increased risk of hypomagnesemia compared with controls. The risk seems to be even higher for panitumumab, probably correlated with the increased risk of other adverse events (e.g., diarrhea and dehydration). Hypomagnesemia does not seem to be linked with any serious complications.