Early magnesium reduction in advanced colorectal cancer patients treated with cetuximab plus irinotecan as predictive factor of efficacy and outcome.
BACKGROUND
Magnesium plays a role in a large number of cellular metabolic reactions. Cetuximab is able to induce hypomagnesemia by interfering with magnesium (Mg(2+)) transport in the kidney. We designed this trial to investigate if Mg(2+) serum level modifications may be related with clinical response and outcome in advanced colorectal cancer patients during treatment with cetuximab plus irinotecan.


METHODS
Sixty-eight heavily pretreated metastatic colorectal cancer patients were evaluated for Mg(2+) serum levels at the following time points: before; 6 hours; and 1, 7, 14, 21, 50, and 92 days after the start of treatment.


RESULTS
Basal Mg(2+) median levels were significantly decreased just 7 days after the first anticancer infusion and progressively decreased from the 7th day onward, reaching the highest significance at the last time point (P < 0.0001). Twenty-five patients showed a reduction in median Mg(2+) circulating levels of at least 20% within the 3rd week after the first infusion. Patients with this reduction showed a response rate of 64.0% versus 25.6% in the nonreduced Mg(2+) group. The median time to progression was 6.0 versus 3.6 months in the reduced Mg(2+) group and in that without reduction, respectively (P < 0.0001). Overall survival was longer in patients with Mg(2+) reduction than in those without (10.7 versus 8.9 months).


CONCLUSIONS
Our results confirm that cetuximab treatment may induce a reduction of Mg(2+) circulating levels and offer the first evidence that Mg(2+) reduction may represent a new predictive factor of efficacy in advanced colorectal cancer patients treated with cetuximab plus irinotecan.
Vincenzi
Bruno
B
Department of Medical Oncology, Laboratory Medicine, and Radiology, University Campus Bio-Medico, Rome, Italy.
Santini
Daniele
D
Galluzzo
Sara
S
Russo
Antonio
A
Fulfaro
Fabio
F
Silletta
Marianna
M
Battistoni
Fabrizio
F
Rocci
Laura
L
Zobel
Bruno Beomonte
BB
Adamo
Vincenzo
V
Dicuonzo
Giordano
G
Tonini
Giuseppe
G
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000911:Antibodies, Monoclonal / Q000008:administration & dosage*; D061067:Antibodies, Monoclonal, Humanized; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D002166:Camptothecin / Q000008:administration & dosage / Q000031:analogs & derivatives*; D000068818:Cetuximab; D015179:Colorectal Neoplasms / Q000188:drug therapy*; D018450:Disease Progression; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D000077146:Irinotecan; D008274:Magnesium / Q000737:chemistry; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D016896:Treatment Outcome
D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000077146:Irinotecan; D008274:Magnesium; D000068818:Cetuximab; D002166:Camptothecin