Identification of risk factors is a fundamental goal of melanoma studies. The current understanding of melanoma progression is based primarily on two-stage modeling. A multistate Markov chain process combined with Cox proportional hazard regression is used to model the melanoma progression. The model is applied to 3,434 patients initially diagnosed as AJCC stage I or stage II. Parameter estimates are obtained using Cox regression and supplemented by plots of survival probabilities. Age is associated with increased risk of progression from stage I, II to stage III and from stage III to stage IV. Males experienced an increased risk of stage I, II to stage III progression. Primary tumor located on extremities decreased the risk of all transitions. Clark's level of invasion >III and Breslow's depth >1 mm increased the risk of progression from stage I, II to stage III and stage IV. The following interactions among the prognostic factors were identified for the first time in this research: interaction of age and gender in progression from stage I, II to stage III; interactions of level and depth and site by gender were found in the progression from stage I, II to stage III; interaction of site and gender in progression from stage III to stage IV and stage IV to death. Also we identified primary site as a new prognostic factor for the progression from stage IV to death. The study employed a multistate model in order to identify prognostic factors relevant for disease progression. The unique feature is the modeling of interactions among the prognostic factors and their identification.

Adult↗

PubMedDate not supplied

Disposition of RS-26306, a potent luteinizing hormone-releasing hormone antagonist, in monkeys and rats after single intravenous and subcutaneous administration.

The metabolic disposition of RS-26306, a new potent luteinizing hormone-releasing hormone antagonist, was studied in rats and monkeys after single i.v. and sc administration with the 3H-labeled compound. Plasma pharmacokinetics after iv administration were: CLs = 2.5 ml/min/kg, Vd beta = 0.29 liter/kg, t1/2 = 1.4 hr (rats), and CLs = 0.8 ml/min/kg, Vd beta = 0.32 liter/kg, t1/2 = 5.1 hr (monkeys). Cmax and Tmax in rats were 0.53 micrograms/ml and 4 hr after the 1 mg/kg sc dose, and were 1.07 micrograms/ml and 12 hr after the 10 mg/kg sc dose. AUC0-infinity after the 10 mg/kg sc dose in rats was seven times that after the 1 mg/kg sc dose. Apparent plasma disappearance t1/2 in rats were 3.6 and 15.2 hr, respectively, after the 1 and 10 mg/kg sc doses. An average of 12 and 4% of dose radioactivity remained at the injection site in rats 3 and 10 days, respectively, after a 10 mg/kg sc dose. In monkeys, Tmax after a 1 mg/kg sc dose was 0.5 hr for three animals but was 24 hr for the fourth animal, although plasma of this monkey contained substantial levels of RS-26306 between 15 min and 24 hr. Apparent plasma t1/2 in monkeys after a 1 mg/kg sc dose was at least 19 hr. Our data suggest depot formation after sc doses. In vitro plasma binding amounted to 82-84%. Excretion was mainly biliary: 12-25 and 55-84% of dose radioactivity was recovered in urine and feces, respectively, in both species. The biological samples contained only traces of 3H2O. Three metabolites, which were truncated peptides of the parent decapeptide, were identified in the rat bile. One of these was also present in the monkey plasma. The restricted enzymatic degradation of RS-26306, extensive plasma binding, and long circulating t1/2 of RS-26306 contribute to its prolonged activity in animal models and in humans.

Animals↗