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Brain cancer is regarded as one of the most life-threatening forms of cancer worldwide. Oxidative stress acts to derange normal brain homeostasis, thus is involved in carcinogenesis in brain. The Nrf2/Keap1/ARE pathway is an important signaling cascade responsible for the maintenance of redox homeostasis, and regulation of antiinflammatory and anticancer activities by multiple downstream pathways. Interestingly, Nrf2 plays a somewhat, contradictory role in cancers, including brain cancer. Nrf2 has traditionally been regarded as a tumor suppressor Show less

Brain cancer is regarded as one of the most life-threatening forms of cancer worldwide. Oxidative stress acts to derange normal brain homeostasis, thus is involved in carcinogenesis in brain. The Nrf2/Keap1/ARE pathway is an important signaling cascade responsible for the maintenance of redox homeostasis, and regulation of antiinflammatory and anticancer activities by multiple downstream pathways. Interestingly, Nrf2 plays a somewhat, contradictory role in cancers, including brain cancer. Nrf2 has traditionally been regarded as a tumor suppressor Show less

Purpose

Oxaliplatin causes disabling acute and chronic peripheral neuropathy. We explored the preventive effects of calmangafodipir, mimicking the mitochondrial enzyme manganese superoxide dismutase, thereby protecting cells from oxidative stress, in a placebo-controlled, double-blinded randomised phase II study (ClinicalTrials.gov.NCT01619423) in patients with metastatic colorectal cancer (mCRC).

Patient and methods

mCRC patients treated with modified FOLFOX-6 (folinic acid 200 mg/m², 5-fluorouracil bolus 400 mg/m², oxaliplatin 85 mg/m² and 5-fluorouracil 2400 mg/m² continuous infusion for 46 h) every fortnight for 8 cycles in first or second line were eligible. Calmangafodipir was given in a phase I dose-finding and in a phase II placebo-controlled study, as a 5-min infusion 10 min prior to oxaliplatin. Neurotoxicity was evaluated by the physician using the Oxaliplatin Sanofi Specific Scale and by the patient using the cold allodynia test and the Leonard scale.

Results

Eleven patients were included in phase I without any detectable toxicity to calmangafodipir. In the phase II study, 173 patients were randomised to placebo (n = 60), calmangafodipir 2 µmol/kg (n = 57) and calmangafodipir 5 µmol/kg (n = 45, initially 10 µmol/kg, n = 11). Calmangafodipir-treated patients (all three doses pooled) had less physician graded neurotoxicity (odds ratio (90% confidence interval one-sided upper level) 0.62(1.15), p = .16), significantly less problems with cold allodynia (mean 1.6 versus 2.3, p < .05) and significantly fewer sensory symptoms in the Leonard scale (cycle 1-8 mean 1.9 versus 3.0, p < .05 and during follow-up after 3 and 6 months, mean 3.5 versus 7.3, p < .01). Response rate, progression-free and overall survival did not differ among groups.

Conclusions

Calmangafodipir at a dose of 5 µmol/kg appears to prevent the development of oxaliplatin-induced acute and delayed CIPN without apparent influence on tumour outcomes. Show less

NFE2-related factor 2 (NRF2) has apparently contradictory roles in cancer. Activation of NRF2 contributes to the chemopreventive effects of various clinically used drugs against various diseases including cancer. However, NRF2 activity can also accelerate tumorigenesis in mouse models, thus highlighting a potential danger of NRF2 activation. This Opinion article discusses how these opposing roles might be reconciled. Show less