Acute oxaliplatin-induced peripheral nerve hyperexcitability.

PURPOSE: Oxaliplatin is a novel platinum compound with clinical activity in several malignancies. Neurotoxicity is dose-limiting and occurs in two distinct forms, an acute neurologic symptom complex that occurs within hours or days of therapy and a chronic, cumulative sensory neuropathy. PATIENTS AND METHODS: Patients were treated in a phase I study designed to establish the maximum-tolerated dose of capecitabine given with oxaliplatin. Because of the unusual neurosensory toxicity of oxaliplatin, detailed neurologic examination, needle electromyography (EMG), and nerve conduction studies (NCS) were performed before and the day after oxaliplatin in a subset of 13 patients. Carbamazepine therapy was tried in 12 additional patients to determine whether the neurologic effects might be relieved. RESULTS: All patients experienced acute, reversible neurotoxicities with oxaliplatin. Symptoms included paresthesias, dysesthesias, cold hypersensitivity, jaw pain, eye pain, pain in the arm used for drug infusion, ptosis, leg cramps, and visual and voice changes. Serial EMG and NCS revealed striking signs of hyperexcitability in motor nerves after oxaliplatin. In patients who achieved therapeutic levels, carbamazepine did not alter the clinical or electromyographic abnormalities. CONCLUSION: The acute neurotoxicity seen with oxaliplatin is characterized by peripheral-nerve hyperexcitability, and the findings are similar to the clinical manifestations of neuromyotonia. Carbamezepine, which provides symptomatic relief in acquired neuromytonia, did not seem to be beneficial. Efforts to identify a successful neuroprotectant strategy would have a major impact on improving patient quality of life and the ability to deliver full doses of oxaliplatin.

Survey of oxaliplatin-associated neurotoxicity using an interview-based questionnaire in patients with metastatic colorectal cancer.

BACKGROUND: New chemotherapy regimens for patients with colorectal cancer have improved survival, but at the cost of clinical toxicity. Oxaliplatin, an agent used in first-line therapy for metastatic colorectal cancer, causes acute and chronic neurotoxicity. This study was performed to carefully assess the incidence, type and duration of oxaliplatin neurotoxicity. METHODS: A detailed questionnaire was completed after each chemotherapy cycle for patients with metastatic colorectal cancer enrolled in a phase I trial of oxaliplatin and capecitabine. An oxaliplatin specific neurotoxicity scale was used to grade toxicity. RESULTS: Eighty-six adult patients with colorectal cancer were evaluated. Acute neuropathy symptoms included voice changes, visual alterations, pharyngo-laryngeal dysesthesia (lack of awareness of breathing); peri-oral or oral numbness, pain and symptoms due to muscle contraction (spasm, cramps, tremors). When the worst neurotoxicity per patient was considered, grade 1/2/3/4 dysesthesias and paresthesias were seen in 71/12/5/0 and 66/20/7/1 percent of patients. By cycles 3, 6, 9, and 12, oxaliplatin dose reduction or discontinuation was needed in 2.7%, 20%, 37.5% and 62.5% of patients. CONCLUSION: Oxaliplatin-associated acute neuropathy causes a variety of distressing, but transient, symptoms due to peripheral sensory and motor nerve hyperexcitability. Chronic neuropathy may be debilitating and often necessitates dose reductions or discontinuation of oxaliplatin. Patients should be warned of the possible spectrum of symptoms and re-assured about the transient nature of acute neurotoxicity. Ongoing studies are addressing the treatment and prophylaxis of oxaliplatin neurotoxicity.

Pharmacokinetic and pharmacodynamic effects of oral eniluracil, fluorouracil and leucovorin given on a weekly schedule.

PURPOSE: To determine the toxicities and pharmacokinetic effects of eniluracil (EU) given on two weekly dosing schedules with 5-fluorouracil (5-FU) and leucovorin (LV). METHODS: A group of 26 patients received a single 24-h i.v. infusion of 5-FU 2300 mg/m(2) to provide a pharmacokinetic reference. After 2 weeks, patients received oral EU 20 mg plus LV 30 mg on days 1-3 with a single dose of 5-FU 15-29 mg/m(2) on day 2, or LV 30 mg on days 1-2 with a single dose of EU at least 1 h prior to 5-FU 29 mg/m(2) on day 2 weekly for 3 of 4 weeks. RESULTS: Diarrhea was the most common dose-limiting toxicity. The recommended dose of 5-FU is 29 mg/m(2) per day. EU on either schedule decreased 5-FU plasma clearance by 48 to 52-fold, prolonged the half-life to >5 h, and increased the percentage of 5-FU excreted in the urine from 2% to 64-66%. With EU, plasma fluoro-beta-alanine was not detected while urinary excretion was reduced to <1% of that seen with i.v. 5-FU alone. Marked increases in both plasma and urinary uracil were seen. Thymidylate synthase ternary complex formation was demonstrated in bone marrow mononuclear cells isolated 24 h after the first oral 5-FU dose; the average was 66.5% bound. CONCLUSIONS: Either a single 20-mg dose of EU given prior to or for 3 days around the oral 5-FU dose led to comparable effects on 5-FU pharmacokinetic parameters, and inhibition of dihydropyrimidine dehydrogenase and thymidylate synthase.

New targeted therapies in gastrointestinal cancers.

Despite surgical, radiotherapeutic, and chemotherapeutic advances, a large proportion of gastrointestinal (GI) cancers remain incurable. An improved understanding of the molecular pathogenesis of cancer has promulgated the development of novel agents designed to target critical pathways involved in cancer development and progression. The crucial role of the epidermal growth factor receptor (EGFR) in tumor proliferation and the overexpression of EGFR in several GI cancers provides the rationale for targeting and interrupting this key signaling network. EGFR blockade through monoclonal antibodies (C225 and ABX-EGF) and tyrosine kinase inhibitors (ZD1839 and OSI-774) has translated into promising evidence of clinical benefit. Ras-mediated signal transduction has been targeted using inhibitors of farnesyl transferase (R115777 and SCH66336) to block the post-translation modification of Ras. Inhibitors of vascular growth factor receptor (bevacizumab and PTK787) and matrix metalloproteinase target the effects of the host environment. Cyclooxygenase-2 inhibitors in colorectal cancer and STI571 in GI stromal tumors represent novel therapies of interest for these specific GI cancers. Evidence suggests that novel agents can be administered alone or in combination with standard therapies with little additional toxicity. The results of ongoing and future research efforts will clarify the optimal use and survival benefit of targeted therapies for patients with GI malignancies.

Hypersensitivity and idiosyncratic reactions to oxaliplatin.

BACKGROUND: Oxaliplatin is a third-generation platinum analog that is used to treat a variety of solid tumors, particularly colorectal carcinoma. Patients may develop hypersensitivity reactions, although this complication occurs infrequently. METHODS: Three patients developed hypersensitivity reactions to oxaliplatin while undergoing treatment on a Phase I trial of oxaliplatin and capecitabine. An Entrez PUBMED search was performed to identify other cases. RESULTS: Two patients experienced the abrupt onset of erythema alone or with pruritus during the 9th and 11th infusions of oxaliplatin, whereas the other patient developed fever and mild dyspnea a few hours after the 9th oxaliplatin infusion. All 3 patients were rechallenged successfully for at least 1 additional oxaliplatin infusion by using oral dexamethasone, 20 mg orally, 6 and 12 hours before the administration of oxaliplatin and by administering intravenously 125 mg of solumedrol, 50 mg of diphenhydramine, and 50 mg of cimetidine 30 minutes before oxaliplatin. The literature review suggests two distinct patterns of reactions: classic hypersensitivity (as experienced by the first two patients) and idiosyncratic reactions (as experienced by the third patient). CONCLUSIONS: Patients who develop mild to moderate hypersensitivity to oxaliplatin may be pretreated with steroids and antagonists of Type 1 and 2 histamine receptors, whereas patients who develop severe reactions are unlikely to tolerate further therapy.