Effect of ultrafilterable platinum concentration on cisplatin and carboplatin cytotoxicity in human tumor and bone marrow cells in vitro

The importance of the ultrafilterable platinum (fPt) fraction of cisplatin (CDDP) and carboplatin (CBDCA) for cytotoxicity and myelotoxicity was studied in vitro. By incubating CDDP or CBDCA with fetal calf serum (FCS) various fractions of fPt were prepared and determined by atomic absorption spectroscopy. A relation of % fPt fraction and incubation time (h) of 87e-0.1123t (r = -0.99) and 101e-0.0087t (r = -0.99) were determined for CDDP and CBDCA, respectively. Cytotoxicity in the human small cell lung carcinoma cell line GLC4 and fPt fraction were closely related for CDDP (r = 0.99) and for CBDCA r = 0.97). However, at a similar fPt fraction the concentrations inhibiting cell survival by 50% (IC50) of CBDCA exceeded that of CDDP by a factor of 10-18 with 4 h exposure and a factor of 5 with continuous exposure. Tested in the range of peak concentrations in plasma of patients and at a clinically relevant fPt fraction of 10%, CDDP was not toxic for human bone marrow cells in the CFU-GM assay, whereas it was toxic at fPt fractions of 50% and 90%. However, CBDCA was myelotoxic at a (clinically relevant) fPt fraction of 50%, and also at 75% and 90%. The use of different fPt fractions, produced by the incubation method described in this study, permits the study of platinum drugs in vitro while approximating in vivo conditions might be used to evaluate myelotoxicity of new platinum drugs prospectively. For CDDP and CBDCA the fraction fPt determines cytotoxicity on tumor cells, and their different fPt fraction in patients account at least partly for their difference in myelotoxicity.

Clinical, toxicological and pharmaceutical aspects of the antineoplastic drug taxol: a review

Taxol, a diterpene alkaloid isolated from the bark of Taxus brevifolia, has a unique mechanism of action. The drug promotes the formation of microtubule polymers in a cell, by reversibly and specifically binding the beta-subunit of tubulin. Taxol is administered intravenously by a 3-24-hour infusion at 3-week intervals. Myelosuppression, especially neutropenia, appears to be the dose limiting toxicity in solid tumours at 200-250 mg/m2. Furthermore, side effects such as sensory neurotoxicity (with typical numbness, tingling and painful paraesthesiae in the extremities), diarrhoea and alopecia appear frequently. Mucositis appears to be the non-haematological dose limiting side effect at 390 mg/m2 that has been determined in patients with leukaemia. Hypersensitivity reactions, which have been fatal in individual cases, might be schedule dependent. Furthermore, antiallergic prophylaxis must be given, although this precaution might not be considered to be fully protective. Phase I studies performed with combinations of taxol and cisplatin, doxorubicin or cyclophosphamide have indicated the feasibility of these regimens and show promise for future investigations. Addition of granulocyte-colony stimulating factor (G-CSF), aimed at modulating myelosuppressive toxicity, showed in Phase I studies that the taxol dose could be increased to 250 mg/m2, with peripheral neuropathy as the dose limiting toxicity. In Phase II studies, taxol has been shown to be effective, including producing complete tumour remission, in advanced drug refractory ovarian carcinoma (19%-36% response rate), previously treated patients with metastatic breast carcinoma (27%-62% response rate), advanced non-small lung cancer (21%-24% response rate), advanced small cell lung cancer (37% response rate) and advanced head and neck cancer (34% response rate).(ABSTRACT TRUNCATED AT 250 WORDS)

Enhancement of cisplatin and etoposide cytotoxicity after all-trans retinoic-acid-induced cellular differentiation of a murine embryonal carcinoma cell line

The potential of a combination of differentiation induction and chemotherapy was analyzed. Treatment of the murine embryonal carcinoma (EC) cell line PCC4 in vitro with all-transretinoic acid (RA) was followed by exposure to cisplatin (CDDP) or etoposide (VP-16). The expression of EC-cell-specific markers decreased upon 96 hr exposure to 10(-9), 10(-8), 10(-7) and 10(-6) M RA, indicating a loss of embryonal phenotype of the cells, whereas expression of markers specific for cytokeratins and neurofilaments was increased after this treatment. These data suggest early somatic differentiation of PCC4 cells upon treatment with RA. Cellular growth rate of PCC4 cells was not affected by preincubation with RA at 10(-9) M for 96 hr, but was reduced at 10(-8) and 10(-7) M RA and inhibited at 10(-6) M RA. Culture of PCC4 cells in the presence of 10(-7) M RA for 96 hr led to accumulation in G1 of the cell cycle, whereas at 10(-8) M RA cell-cycle distribution was not affected. RA-treated and -untreated PCC4 cells were compared for CDDP and VP-16 sensitivity. Pre-treatment with 10(-9), 10(-8) and 10(-7) M RA increased CDDP sensitivity, resulting in a 1.9-, 2.7- and 2.6-fold decrease in the concentrations inhibiting survival by 50% (IC50s) respectively. Pre-treatment with 10(-8) and 10(-7) M RA increased VP-16 sensitivity 2.5- and 3.0-fold, respectively. Enhanced CDDP sensitivity at RA concentrations not affecting cell-cycle distribution was not attributable to changes in cellular platinum (Pt) accumulation, or to changes of Pt-DNA binding.(ABSTRACT TRUNCATED AT 250 WORDS)

A phase I study of lobaplatin (D-19466) administered by 72 h continuous infusion

A phase I trial with continuous intravenous infusion of lobaplatin (D-19466; 1,2-diamminomethyl-cyclobutane-platinum (II)-lactate) for 72 h was performed to determine the maximum tolerated dose (MTD). Each patient received a single dose level, the total dose of lobaplatin ranged from 30 to 60 mg/m2/72 h every 4 weeks. Eleven patients enroled in this study and received a total of 30 courses of lobaplatin (median 2; range 1-6). Thrombocytopenia was the dose-limiting toxicity, it reached WHO grade III in three out of six patients at 45 mg/m2/72 h, and WHO grade IV in two out of two patients at 60 mg/m2/72 h. Leucocytopenia was mild, as was nausea and vomiting. Phlebitis at the infusion site was found in three patients. During this trial there were no signs of renal, neuro- or ototoxicity. One patient with ovarian cancer, pretreated with three different platinum complexes, achieved a partial response now lasting for longer than 6 months. In conclusion, thrombocytopenia is the dose-limiting toxicity of lobaplatin administered by 72 h continuous infusion. The recommended phase II dose for this regimen is 45 mg/m2/72 h every 4 weeks.

A phase I study of 1,2-diamminomethyl-cyclobutane-platinum (II)-lactate (D-19466; lobaplatin) administered daily for 5 days

A phase I trial was conducted with lobaplatin (D-19466; 1,2-diamminomethyl-cyclobutane-platinum (II)-lactate) i.v. bolus daily for 5 days every 4 weeks. After entering five patients toxicity appeared to be related to renal function, therefore the individual dose (total dose 20-100 mg m-2 over 5 days) of lobaplatin was modified according to creatinine clearance (CRCL) and escalated in patients. Twenty-seven patients with refractory solid tumours received 72 courses. Thrombocytopenia was dose-limiting, its degree was related to dose and CRCL at time of drug administration. With a CRCL of 60-80 ml min-1 the maximum tolerated dose was 40 mg m-2, with a CRCL of 81-100 ml min-1 70 mg m-2, and with a CRCL > 100 ml min-1 it was 85 mg m-2. Platelet and leukocyte nadirs were observed around day 21. The percentual platelet nadir (percentage of day 1 platelet count) correlated with CRCL at different dose levels and could be described by 0.76 x CRCL (ml min-1) - (1.45 x dose (mg m-2) + 43.38. This equation tested in 20 patients (28 courses) produced a correlation between observed and predicted percentual platelet nadir (r = 0.82, P < 0.001). No renal function impairment occurred. Urinary excretion of platinum (by A.A.S) was estimated in six patients and revealed that 91.5% (s.e. +/- 7.9) of the platinum dose was excreted within 4 h. Responses (one PR, one CR) occurred in two patients with ovarian cancer (both pretreated with carboplatin and cisplatin). The recommended dose of lobaplatin i.v. bolus daily for 5 days for phase II studies depends on renal function, namely 30 mg m-2 at CRCL 60-80 ml min-1; 55 mg m-2 at CRCL 81-100 ml min-1; 70 mg m-2 at CRCL > 100 ml min-1.

Combination therapy with cisplatin: modulation of activity and tumour sensitivity

Although cisplatin is applied with success in clinical oncology, this success is limited because some cancers are initially unresponsive to cisplatin or become so during treatment. In this review, some strategies to overcome this problem are discussed. Among these are combination with the differentiation inducing agent, retinoic acid, combination with radiotherapy, and the use of hyperthermia.

Stability of the new anticancer platinum analogue 1,2-diaminomethyl-cyclobutane-platinum(II)-lactate (lobaplatin; D19466) in intravenous solutions

The chemical stability of the new anticancer platinum analogue 1,2-diaminomethyl-cyclobutane-platinum(II)-lactate (D19466) in infusion media was studied in an accelerated stability testing experiment with a selective HPLC-UV method. Variables were time, temperature, light, concentration, and infusion mixture. Mean reaction rate constants of decomposition were, respectively, 0.9555 *10(-2), 2.127 *10(-2), and 4.221 *10(-2) hr-1 at 37, 56, and 66 degrees C at a concentration of 200 mg/L in normal saline. From the Arrhenius equation, shelf lives (5% loss) at 4, 22, 37, and 121 degrees C were, respectively, calculated to be 41.6, 13.2, 5.7, and 0.15 hr. Mean reaction rate constant in 5% dextrose was 3.106 *10(-2) hr-1 (200 mg/L; 56 degrees C) and differed from that in normal saline (P less than 0.005). Mean reaction rate constant in Ringer lactate was 2.084 *10(-2) hr-1 (200 mg/L; 56 degrees C) (P greater than 0.05). There was no influence of normal daylight on the rate of decomposition. It is recommended to prepare D19466 infusions in normal saline. Chemical stability is then maximal 12 hr at room temperature or 24 hr at 4 degrees C. No protection against normal daylight is required. Sterilization by heat is not possible.

Pharmacokinetics of parenteral 13-cis-retinoic acid formulations in rats

The pharmacokinetics of three 13-cis-retinoic acid formulations were studied after intraperitoneal (ip) administration to rats. Rats were given ip injections of 2.5 mg of 13-cis-retinoic acid per 360 g of body weight; the drug was administered as an alkaline solution, suspended in corn oil, or as a mixture with polysorbate 80. The alkaline solution was also given intravenously (iv) via the tail vein as a control. The mean elimination rate constant, calculated from data from iv administration, was 0.72 +/- 0.088 h-1 (r = 0.988). The peak concentration in plasma and the time to reach this maximum were 14 mg/L and 0.5 h, 22 mg/L and 2 h, and 10 mg/L and 1 h for the drug administered as an alkaline solution, suspended in corn oil, and as a mixture with polysorbate 80, respectively. The areas under the concentration-time curve (concentration in plasma versus time) were 34.9 +/- 8.78 mg.h/L for the iv dose and 34.1 +/- 9.97, 62.4 +/- 32.3, and 25.9 +/- 12.0 mg.h/L for the ip doses of alkaline solution, suspension in oil, and mixture with polysorbate 80, respectively. Because of the rapid increase of concentration in plasma, which is identical to that of the iv profile, and the ease of its handling and preparation, the ip administered alkaline solution is the preferable formulation.