LEAn Body Mass Normalization of OXaliplatin Based Chemotherapy for Stage III Colon Cancer Patients Treated in Adjuvant Setting: Impact on Oxaliplatin-induced Sensitive Neurotoxicity. A Multicenter Phase II Randomized Trial (LEANOX)

Adjuvant chemotherapy with fluoropyrimidines and Oxaliplatin is the current worldwide standard of care for stage III colorectal cancer (CRC). This regimen leads to significant cost, toxicity, and patient inconvenience. Oxaliplatin induces two distinct forms of neuropathy: a common acute syndrome that is transient (dysesthesia, contractures and numbness) and a dose-limiting chronic sensory neurotoxicity that is cumulative. Neurotoxicity is common; it affects 80% of patients and becomes chronic in 15-20% of cases, sometimes irreversibly. Chronic neurotoxicity can severely affect everyday life activities. To date, neuromodulators agents have failed to prevent neurotoxicity and Stop & Go strategies, intended to decrease the cumulative dose of Oxaliplatin administrated, are more appropriate for palliative treatment of advanced CRC. Recent data support the plausibility of a shorter duration of adjuvant treatment without loss of efficacy. This hypothesis is tested in several international trials.

Cytotoxic chemotherapy is usually scaled to the body surface area (BSA), and is currently not adjusted to the body proportions of lean and fat (i.e. body composition) of individual patients. The impact of body composition on drug metabolism is however well known: i.e. anesthetics accumulate in adipose tissue and specific precautions are essential to avoid overdose. Concerning chemotherapies, the lean body mass (LBM) may be the salient feature defining drug metabolism. A theme is emerging from recent studies: in patients with breast cancer and treated with 5-FU (whose dosage was calculated from the body surface), severe depletion of the LBM is a powerful predictor of excessive toxicity. Indeed, depletion of the LBM, as precisely defined by computed tomography, is a unique predictor of clinically unacceptable toxicity. Low LBM was shown to be a significant predictor of dose-limiting toxicity (DLT) in CRC patients administered 5-FU using a conventional BSA-based dosing and DLT was concentrated in patients receiving >20 mg 5FU/kg LBM. Two cohorts of CRC patients treated with Oxaliplatin showed that overall DLTs, and specifically Oxaliplatin-due neuropathy, occurred mostly in patients who receive > 3.09 mg/Oxaliplatin/kg LBM. Although, preliminary findings are available in hepatocellular carcinoma, the area under the concentration time curve (AUC) of Sorafenib cancer therapy was doubled in patients with depleted LBM (102.4 vs. 53.7ng/mL.h), which seem of interest. Patients with low muscle mass behave like patients "overdosed" with chemotherapy resulted in dose-limiting toxicities (e.g. dose reductions, treatment delays or permanent treatment discontinuation), independently of the patient's weight.