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Query: UMLS:C0020437 (hypercalcemia)
 10,293 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Carbetimer is a new antineoplastic agent whose main side effects consist of neurotoxicity and long-term dose-dependent hypercalcemia. We previously showed that Carbetimer is a potent calcium chelator responsible for an acute decrease in ionized Ca levels observed in vivo. However, the mechanism of the progressive increase in serum Ca remains unknown. We have evaluated the bone-resorbing effects of Carbetimer on 45Ca-prelabelled neonatal mouse calvariae. Carbetimer induced a dose-dependent increase in 45Ca release which started at a concentration of 1 mg/ml and reached a mean of 3.3 times the control values at 10 mg/ml. This marked increase in 45Ca release was similar on previously killed bones and could not be inhibited by calcitonin. Such concentrations are probably therapeutically relevant given the known affinity of Carbetimer for bone and the large daily doses administered to cancer patients (10-15 g). Since Carbetimer could exert its antineoplastic action through immunomodulation, we also studied its effects on the production of TNF-alpha and IFN-gamma which are also known to affect bone metabolism. Carbetimer did not stimulate TNF-alpha release from isolated normal human monocytes or lymphocytes, but it markedly inhibited T-lymphocyte production of IFN-gamma, which became undetectable at a concentration of 1 mg of Carbetimer/ml. In summary, Carbetimer-induced hypercalcemia appears to be due to a direct stimulation of osteolysis, but possibly also to an inhibition of IFN-gamma production.
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PMID:Effects of Carbetimer, a new antineoplastic drug, on bone metabolism. 191 Sep 54

Carbetimer (carboxyimamidate) is a low molecular weight derivative of ethylene/maleic anhydride polymer. This compound has demonstrated antitumor activity against several animal models with a daily x 5 schedule appearing most effective. A phase I clinical study of the daily x 5 schedule repeated every 28 days was therefore performed. Forty-one evaluable patients received 66 evaluable cycles of Carbetimer at daily doses ranging from 100-11,000 mg/m2. Hypercalcemia was the dose limiting toxicity with both patients at the 11,000 mg/m2 daily dose level and one patient who received 6 cycles of drug at the 4200 mg/m2 dose level developing severe hypercalcemia not explained by the underlying malignancy. Mild nausea, concentration and rate dependent arm pain at the site of infusion, proteinuria, and coagulopathy were also seen. Calcium balance studies revealed hypercalciuria, suggesting increased mobilization of calcium rather than renal retention. In vitro coagulation studies revealed concentration dependent prolongation of the partial thromboplastin time and thrombin time. No complete or partial responses were seen. However mixed response or biochemical response (reduction in serum lactic dehydrogenase) were seen in 5 patients with melanoma or renal cancer. Due to unacceptable toxicity at the 11,000 mg/m2 daily dose level, Carbetimer 8500 mg/m2 is the recommended dose for a 5-day treatment schedule every 28 days. Special attention should be directed toward possible activity against melanoma and renal cancer.
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PMID:Phase I trial of a 5-day course of carbetimer. 238 16

Carbetimer, a low molecular weight polymer derived from ethylene and maleic anhydride, belongs to a class of chemical compounds different from previously available anticancer agents. It has shown moderate antitumor activity against the Madison 109, Lewis lung, colon 26 and M5076 ovarian carcinomas. In the human tumor stem cell assay, antitumor activity was seen against carcinomas of the breast, ovary, lung, colon and kidney. A total of 26 patients with solid tumors were entered into this trial; carbetimer was given on 5 consecutive days as a 1-2-h intravenous infusion. The dose was escalated from 1.08 to 11 g/m2/day. The drug did not induce the usual side-effects of chemotherapy: leukopenia, thrombocytopenia, alopecia and mucositis were minimal or totally absent. Gastrointestinal toxicity was limited to mild to moderate nausea and vomiting; these were observed at all dose levels and required antimetics in only two patients. The major side-effects of carbetimer consisted of hypercalcemia and neurotoxicity. Hypercalcemia was dose- and treatment duration-dependent. The precise mechanism of hypercalcemia is presently under investigation, but remains unclear. Neurotoxicity was observed only after prolonged therapy; two patients, who received cumulative doses higher than 250 g/m2, developed a peripheral neuropathy with paresthesia, decrease in sensory perception and motor weakness. One patient recovered completely; the other patient improved slightly before developing fatal brain metastases. Two patients with malignant melanoma exhibited major antitumor response; both were previously treated; after excellent partial responses to carbetimer, both were operated on and one is presently disease-free 2 1/2 years after completion of therapy with carbetimer. In conclusion, carbetimer is a new compound with an unusual pattern of side-effects and interesting antitumor activity against malignant melanoma. Its antitumor activity is presently being investigated in phase II trials.
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PMID:Phase I clinical trial with carbetimer. 253 92

Carbetimer is a new antineoplastic agent whose limiting toxicity consists of dose- and treatment duration-dependent hypercalcemia. We examined the short-term effects of Carbetimer on calcium metabolism on days, 1, 3 and 5 during 11 5-day courses (6.5-8.2 g/m2/day given over daily 2-h infusions, q 3-4 weeks). Blood parameters were measured before and after Carbetimer, whereas urinary parameters were studied in three consecutive 2-h collections before, during and after Carbetimer infusions. Carbetimer effects were similar regardless of the infusion day. We found a consistent decrease of plasma ionized Ca (Ca2+) levels from 4.56 +/- 0.05 mg/dl before infusion to 4.28 +/- 0.06 mg/dl after infusion (P less than 0.001) whereas total serum Ca (corrected for protein levels) did not change. The fall of Ca2+ stimulated parathyroid function, as suggested by the increased plasma PTH levels, the decreased serum phosphorus and TmP/GFR index, or the increased urinary phosphate and cyclic AMP excretion. Carbetimer infusions also induced a marked increase in urinary Ca excretion (expressed as mg Ca/mg creatinine) from 0.093 +/- 0.011 before to 0.359 +/- 0.042 during and 0.177 +/- 0.031 after infusion (P less than 0.011). These changes were best explained by Carbetimer-induced Ca chelation that we confirmed in vitro by incubating Carbetimer at various concentrations in whole blood for 2 h at 37 degrees C, e.g. 2 mg of Carbetimer/ml lowered Ca2+ from 4.82 to 3.20 mg/dl without changing total Ca levels. On the other hand, a direct effect of Carbetimer on bone cannot be excluded since we observed an increase of serum osteocalcin levels from 2.0 +/- 0.3 to 2.5 +/- 0.4 ng/ml after infusion (P less than 0.001). In summary, the short-term effects of Carbetimer on calcium metabolism markedly differ from the long-term effects. They mainly consist of a dose-related calcium chelation leading to a decrease in Ca2+ levels, an increase in urinary Ca excretion and a stimulation of parathyroid function.
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PMID:Short-term effects of Carbetimer on calcium and bone metabolism in man. 263 64

Carbetimer (carbethimer, N-137, NED-137, carboxyimamidate) is a low molecular weight polyelectrolyte with antitumor activity in a variety of tumor models. This phase I trial evaluated a single dose of carbetimer infused over 1-2 h every 28 days. Forty-three patients received 71 courses of the drug at doses ranging from 180 to 8500 mg/m2. The dose-limiting toxicity was hypercalcemia (serum calcium greater than 12.5 mg/dl) noted in two of three patients at a dose of 8500 mg/m2. Serum calcium levels between 10.5 and 12.5 mg/dl were noted in an additional three patients treated at doses greater than or equal to 1600 mg/m2. Calcium balance studies in three patients treated at 6500 mg/m2 revealed an increase in urinary cyclic AMP and phosphate excretion after treatment accompanied by a mild elevation of serum parathyroid hormone. Immunological studies in these patients revealed a statistically significant increase in the percentage of peripheral T-helper cells. An increase in the T-helper/suppressor cell ratio was observed in two of the three patients studied. Interleukin 2 production by phytohemagglutinin-stimulated peripheral mononuclear cells was increased in two of three patients. One patient with a renal cell carcinoma showed a mixed response. The recommended dose for phase II trials as assessed from this study is 6500 mg/m2 as a single dose every 28 days.
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PMID:Phase I clinical trial of carbetimer. 284 47

Carbetimer, a new synthetic low molecular weight polyelectrolyte with a novel structure displayed antitumor activity in a number of animal tumor model systems and in vitro investigations. Based on these findings it was brought to a phase I clinical trial in patients with advanced malignant disease after failure of conventional treatment or with no conventional treatment available. Forty-eight patients received 98 courses. The schedule was a one hour i.v. infusion every four weeks. The starting dose was 180 mg/m2 and dose escalation was performed according to a modified Fibonacci formula up to 16,690 mg/m2. At least three patients were treated at each dose level and each patient was eligible to receive repeat courses at the same dose, until progressive disease or dose-limiting toxicity intervened. No hematological toxicity was encountered. Some adverse effects such as reversible proteinuria, hypercalcaemia, pain at infusion site, nausea and vomiting and fatigue were seen partly in a dose-related manner but did not represent the maximum tolerated dose (MTD). The limiting toxicity at the highest dose level of 16,690 mg/m2 consisted of ocular symptoms ('light flashes') accompanied by a modest decrease of blood pressure and nausea or vomiting during a one hour infusion. 16,690 mg/m2/1 hour was considered the MTD. There were four deaths on study, all considered disease-related. Fourteen patients had stable disease for more than two courses, which, however, could also be explained by the natural course of disease. No clear-cut antitumor responses were noted in our study center. The recommended dose for phase II trials derived from our results is 12,550 mg/m2/2 hours.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Phase I trial of the polyelectrolyte carbetimer administered i.v. once every four weeks. 319 84