Antitumor activity of a new platinum complex, 2-aminomethyl-pyrrolidine (1, 1-cyclobutanedicarboxylato) platinum (II)

One hundred cis-diamminedichloroplatinum (II) (CDDP) analogs have been evaluated for antitumor activity in male CDF1 mice subcutaneously (s.c.) implanted with tumor fragments of Colon 26 carcinoma. Among the complexes tested, 2-aminomethyl-pyrrolidine (1, 1-cyclobutanedicarboxylato) platinum (II) (DWA 2114) had the best antitumor effect. The mice intraperitoneally (i.p.) injected with DWA 2114 at a dose of 40 mg/kg/day on days 4, 6 and 8 after inoculation showed a 97% growth inhibitory ratio (GIR) on day 14 compared to the non-treated control mice. We evaluated the inhibitory effects of DWA 2114 on other tumors, such as Colon 38 carcinoma, Ca 755 mammary adenocarcinoma and L1210 leukemia, and found that it also had antitumor effects on various kinds of tumors. The nephrotoxicity-inducing activity of DWA 2114 and CDDP was evaluated in normal BDF1 mice, as indicated by changes in blood urea nitrogen (BUN) at almost the maximum tolerated dose (MTD) (DWA 2114: 100 mg/kg, CDDP: 12 mg/kg). DWA 2114 had no effect on BUN levels, while CDDP elevated BUN levels. These results indicate that DWA 2114 represents a second generation platinum antitumor complex.     

Antitumor action of cis-dichlorodiammineplatinum(II) and the effectiveness of a combination with sarcolysine

Therapeutic properties of cis-dichlorodiammineplatinum (II) were studied on 12 strains of transplantable tumors and leukemias in mice. The compound is characterized by a wide spectrum of antitumor action. The greatest effect was gained in adenocarcinoma of the lage intestine (strain AKATOL), proventricular cancer (strain PRG) and adenocarcinoma of the mammary gland (strain Ca-755). The terms of survival in mice with leukemia (strain La and L-1210) and ascites hepatoma 22 are increased considerably. In some L-1210 animals the complete cure was noted. Cis-dichlorodiammineplatinum (II) may be effectively combined with sarcolysin. Much greater antitumor effect was obtained on 3 tumor strains (AKATOL, Ca-755 and sarcoma 37) with the combined therapy than with each drug used separately. The histological study of Ca-755 during chemotherapy indicated that immunocompetent cells of the organism play an important role in the mechanism of antitumor action of the platinum complex. This is manifested in the development of intensive lymphohistiocytic reaction around and inside the tumor. A damage to the convoluted tubules of the kidney and intestinal villi is one of the main adverse side-effects of the combination.     

Antitumor activity of a new platinum complex, (R)-(-)-2-aminomethylpyrrolidine (1, 1-cyclobutanedicarboxylato) platinum (II), against cisdiamminedichloroplatinum (II)-resistant murine leukemia cell line

Antitumor activity of a new platinum complex, (R)-(-)-2-aminomethylpyrrolidine (1, 1-cyclobutanedicarboxylato) platinum (II) (DWA 2114 R) against cisdiamminedichloroplatinum (II) (CDDP)-resistant tumor was examined in in vitro and in vivo experiments. CDDP-resistant line was established from L 1210 mouse leukemia cells by continuous exposure to CDDP in dose-escalation manner. Six clones were isolated from parental resistant line and one of these clones, clone f, which was found to be highly resistant (30-40 fold) to CDDP, was used in the following experiments. Clone f showed 4-7 fold cross-resistance to DWA 2114 R and 11-19 fold to cisdiammine-1, 1-cyclobutanedicarboxylatoplatinum (II) (CBDCA) in in vitro growth inhibition assay. DWA 2114 R showed the most effective antitumor activity against mice transplanted with the resistant cells in the increase of life span (ILS%). About 100% of ILS and cured mice were observed in the treatment with DWA 2114 R. On the other hand, CDDP or CBDCA showed a little increase in the survival time (less than 40% of ILS) and all mice died. These results suggest that DWA 2114 R seemed to be more effective against CDDP-resistant tumors clinically than CDDP and CBDCA.     

Antitumor activity of a new platinum complex (R)-(-)-2-aminomethylpyrrolidine (1,1-cyclobutane dicarboxylato) platinum (II) (DWA2114R) by its serial administration

Antitumor activity of a newly synthesized platinum complex, DWA2114R, by the serial administration was examined and compared with that of cis-diammine-1,1-cyclobutane dicarboxylato platinum (II) (CBDCA). In mice transplanted s.c. with tumor, the serial i.p. administration resulted in the increases of both maximal tolerated dose (MTD) and growth inhibitory ratio (GIR) of DWA2114R than single administration. Such increases in MTD and GIR were also shown by CBDCA, but the degree of these increases, such as the ratio of MTD or GIR by the serial administration compared to that at the single administration, was higher in DWA2114R than CBDCA. GIR of DWA2114R by the serial administration was higher than that of CBDCA at the doses to induce the same toxicity which was estimated by body weight loss. In addition, in the experiment using ascites tumor-bearing mice, better antitumor activity of DWA2114R was shown by the elongation of survival time. These results indicate that the cumulative toxicity of DWA2114R is lower than that of CBDCA, which causes the therapeutic advantages of DWA2114R in the serial administration.     

Antitumor effects of three platinum complexes, (-)-(R)-2-aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato)-platinum (II) monohydrate (DWA2114R), cis-diammine-(1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA) and cis-diamminedichloroplatinum(II) (CDDP), in mice.

(-)-(R)-2-Aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato++ +)platinum(II) monohydrate (DWA2114R), cis-diammine(1,1-cyclobutanedicarboxylato)platinum(II) (CBDCA) and cis-diamminedichloroplatinum(II) (CDDP) were compared for their antitumor effects and nephrotoxicity-inducing activities at the same dosage (1/8, 1/4, 1/3, 1/2, 2/3 or 3/4 of the LD10 or LD10) on the basis of their intravenous lethal doses in mice. DWA2114R was effective against murine tumor lines, Colon 26 and Colon 38 carcinomas, M5076 ovarian sarcoma and P388 L1210 leukemias, implanted subcutaneously (s.c.). Triple injection every other day of DWA2114R was more effective than a single injection at each sublethal dose. The antitumor effects of DWA2114R against these tumors were more effective than or were similar to those of CBDCA and CDDP. The antitumor effect against CDDP-resistant L1210 leukemia implanted s.c. was only observed in the treatment of DWA2114R, but not in CBDCA and CDDP. No excellent antitumor effects of three platinum complexes were observed against Lewis lung carcinoma and B16 melanoma implanted s.c. even at triple injection every other day, and no effect was obtained against Meth-A fibrosarcoma under similar conditions. While the treatment of CDDP showed marked increases in levels of blood urea nitrogen and of urinary protein and sugar at effective doses in the antitumor evaluations, the treatment of DWA2114R as well as CBDCA showed no increase in these parameters. These results indicate that DWA2114R represents a desirable second generation antitumor platinum complex.     

Antitumor activity of platinum complexes

Contemporary ideas about the mechanism of antitumor activity of platinum complexes are reviewed and discussed. The induction of SOS functions in bacteria is emphasized and an analogous mechanism in animal cells is suggested. The fate of the leaving ligand in the body is not known. Therefore the complex which reaches the target DNA may be very different from the applied compound. Even the amino ligand may be detached in the body, probably as part of the detoxication by binding to proteins. In the case of fast or medium-speed reactive complexes most of the platinum is inactivated by binding to proteins, whereas slow-reacting drugs are mostly excreted unchanged in the urine. Thus, the quantity of the complex which reaches the target is also difficult to assess. Due to peculiar pharmacokinetics, the results obtained with poorly soluble compounds administered in the solid form cannot be compared with those obtained in true solutions. There are many reasons for believing that the study of a coordination anticancer drug may contribute to our understanding of cancer growth and its reversal.     

A comparative study of the distribution in the male rat of platinum-labelled cis-dichlorodiammine platinum (II), cis-trans-dichlorodihydroxy-bis-(isopropylamine) platinum (I), and cis-dichloro-bis-cyclopropylamine platinum (II)

Summary Three platinum derivatives, cis-dichlorodiammine platinum (II), (DDP), cis-trans-dichlorodihydroxy-bis-(isopropylamine)platinum (IV) (CHIP) and cis-dichloro-bis-cyclopropylamine platinum (II) (CP), have been prepared with a gamma-emitting platinum label. The distribution of these complexes was studied in male rats.The results are presented as fractions of the administered radiolabel per gram of tissue and per total organ. Accumulation in the liver was highest initially following CP and lowest after DDP, but by 14 days the levels in kidney and liver were highest with CP. The concentration in the skin was relatively high after all the compounds, but was the most conspicuous after DDP at the early times. In general, patterns of distribution between the other organs were similar with DDP and CP.CHIP, however, exhibited a different pattern of distribution. Over the first 24 h the level of platinum in most tissues declined more rapidly than after either of the other two compounds but the residual label persisted for a longer period. In the kidney there appeared to be a secondary uptake of labelled material, presumably from other tissues. The level present at 14 days after CHIP was also significantly higher in a number of other organs than after the other two drugs. The increase in label in the spleen at the later times may be due to the removal of circulating damaged cells and consistent with the higher levels of residual platinum in the blood. There was also a higher level of residual platinum in the blood especially after IV administration of the labelled agent.The results show that CHIP was cleared at a faster rate from blood and kidney than the other two complexes, results which closely resembled clinical findings with these three agents, to be published elsewhere.The greater retention time of label after CHIP also suggests that longer-term toxicity may follow its repeated administration. Present address: Radiochemical Centre, Amersham International     

Liposoluble platinum(II) complexes with antitumor activity

Seventeen liposoluble bis(carboxylato)-cyclohexane-1,2-diammineplatinum(II) and bis(carboxylato)-cis-diammineplatinum(II) complexes were synthesized and tested for antitumor activity against leukemia L1210 cells in mice. The former complexes had excellent antitumor activity without any toxicity to the host at the therapeutic dose when used with lipiodol as a carrier solvent. The latter complexes had neither antitumor activity nor toxicity in vivo. The former complexes were gradually released from lipiodol to saline in vitro; the latter were not. The activity depended on the chain length of the carboxylato residue and also on the molecular shape of the ligand part of the complexes.     

Antitumor activity and cellular accumulation of a new platinum complex, (-)-(R)-2-aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato)platinum( II) monohydrate, in cisplatin-sensitive and -resistant murine P388 leukemia cells.

We have examined the cytotoxicity and accumulation of (-)-(R)-2-aminomethylpyrrolidine(1,1-cyclobutanedicarboxylato++ +)platinum(II) monohydrate (DWA2114R) in parent and cisplatin-resistant mouse P388 leukemia cells (P388 and P388/DDP), in comparison with those of cisplatin (CDDP) and carboplatin (CBDCA). The degrees of resistance to CDDP and CBDCA, expressed as the ratio of IC50 for P388/DDP cells to IC50 for P388 cells, were 75-33 and 100-27, respectively, under the conditions of 2-24 h exposure to each drug at a density of 10(6) cells/ml. The corresponding values (25-7) for DWA2114R were relatively low. Accumulations of CDDP and CBDCA were reduced in P388/DDP cells; however, no reduction in accumulation of DWA2114R was observed at various exposure periods and concentrations of the drugs. The accumulations of CDDP in P388 and P388/DDP cells at drug concentrations corresponding to the IC50 values for drug exposure periods of 2-24 h were 0.41-0.97 and 13.1-33.7 ng Pt/10(7) cells, respectively, suggesting that an intracellular mechanism of resistance against CDDP could be activated in P388/DDP cells. P388/DDP cells also showed relatively low resistance to DWA2114R via this mechanism in comparison with CDDP and CBDCA. From the relationship between structure and activity of several Pt-complexes, these different properties of DWA2114R compared with CDDP and CBDCA could be due not only to the differences in carrier ligand structure but also to the properties of the whole molecule associated with the carrier ligand and leaving group.     

Phase II trial of 1,2-diaminocyclohexane-(4-carboxyphthalato) platinum(II) (DACCP) in colorectal carcinoma

In an effort to investigate the antitumor activity of new cisplatin analogues, 1,2-diaminocyclohexane-(4-carboxyphthalato) platinum (II) (DACCP) was administered in a phase II disease-oriented trial to patients with advanced colorectal carcinoma. Six patients had not received prior chemotherapy, while four had received one drug, and two had received more than one drug. Primary sites of disease were in the liver only (8 patients), liver and lung (2 patients), and intra-abdominal (2 patients). Liver radionuclide scans and CT scans were the main parameter for evaluation. The drug was administered intravenously every 4 weeks at a dose of 640 mg/m2. There were no responses in 12 adequately treated patients. One patient had stable disease for 5 months. Nausea and vomiting was milder than that seen with cisplatin. A peripheral neuropathy was seen in four patients. Fever occurred in two patients and urticaria in one patient. No patient had significant drug-induced anemia, and renal dysfunction was not observed. DACCP at this dose and schedule demonstrated no efficacy as a single agent in the treatment of colorectal carcinoma.     

Pharmacokinetics of cis-dichlorodiammine platinum (II) in patients undergoing hemodialysis

The pharmacokinetics of non-protein-bound platinum (free-Pt) and protein-bound platinum derived from cisplatin [cis-dichlorodiammine platinum (II), CDDP] were studied in five patients with chronic renal failure who developed gastric cancer during long-term hemodialysis. Plasma concentrations of CDDP were determined by atomic absorption spectrophotometry. CDDP at a dose of 25 mg/m2 was given i.v. over a 30-min period every one to two weeks. When CDDP was infused simultaneously with the start of hemodialysis, free-Pt at the blood inlet decreased rapidly and free-Pt at the blood outlet remained below the level for quantitative analysis. Furthermore, the total-Pt level declined in two exponential curves at the blood inlet simultaneously with the increased level of Pt at the blood outlet after the end of dialysis. In contrast, when CDDP was infused one hour earlier before dialysis, the pharmacokinetics revealed a higher concentration of free-Pt at the blood inlet which was maintained over a longer period as compared with that occurring when infused simultaneously with the start of dialysis. In conclusion it is considered that this method is feasible for the treatment of gastric cancer in patients with chronic renal failure under long-term hemodialysis.     

Pharmacological and preclinical toxicological studies of 1,2-diaminocyclohexane(isocitrato)platinum(II)

The antitumor activity of a new highly water-soluble platinum derivative, (1,2-diaminocyclohexane)(isocitrato)platinum(II) (NSC 350602; PHIC), was studied in L1210 leukemia cells inoculated into mice. PHIC was found to be active for i.p. graft-i.p. treatment, i.p. graft-i.v. treatment, and i.v. graft-p.o. treatment. A significant activity was observed on early and advanced L1210 leukemia even when the treatment was delayed 6 days after the graft. A comparison between the activities of PHIC, cisplatin (NSC 119875), and (4-carboxyphthalato)(1,2-diaminocyclohexane)-platinum(II) (NSC 271674; DACCP) for i.p. graft-i.p. treatment indicated that the highest activity was observed for divided doses rather than single dose in the case of PHIC and DACCP and not for cisplatin. Under these conditions, PHIC gave larger treated versus control survival time values or a greater number of surviving animals than did cisplatin and DACCP. No cross-resistance between PHIC and cisplatin could be detected in L1210 leukemia cells resistant to cisplatin. Mutagenicity studies on Salmonella typhimurium revealed that PHIC is far less mutagenic than cisplatin on TA100 and TA98 strains. Other pharmacological parameters, such as growth inhibition rate of cultured L1210 cells, penetration, and DNA binding in L1210 cells inoculated in mice, were compared for PHIC and cisplatin together with their in vitro rates of hydrolysis and platinum:DNA adducts. No nephrotoxicity was detected with PHIC at the maximum nonlethal dose level in mice in contrast to results with cisplatin. A preclinical study was conducted in baboons at 100, 150, and 200 mg/kg. No nephrotoxicity could be detected at a dose of 100 mg/kg without prehydration for six courses at 3-week intervals. At 200 mg/kg, an increase of blood creatinine was controlled by prehydration. Gastrointestinal toxicity was mild during the three regimens. Phase I clinical trials are under way.     

The gingival platinum line: a new finding following cis-dichlorodiammine platinum (II) treatment.

Cis-dichlorodiammine platinum (II) (DDP) is the salt of a heavy metal with a wide spectrum of antineoplastic activity. Its toxicity is multisystem and similar to that of other heavy metals, including lead and thallium. A young man being treated with primary adjuvant Adriamycin and DDP for osteogenic sarcoma is described who developed a gingival line which temporally was related to DDP administration. Although not chemically or histologically analyzed, we believe this to be a new finding related to DDP which corresponds to the lead line of plumbism and other heavy metal intoxication.     

In vitro evaluation of dichloro-bis(pyrazole)palladium(II) and dichloro-bis(pyrazole)platinum(II) complexes as anticancer agents

Introduction  Cisplatin (cis-diamminedichloroplatinum) was first identified for its anti-bacterial activity, and was later also shown to be an efficient anticancer agent. However, the therapeutic use of this anticancer drug is somewhat limited by its toxic side effects, which include nephrotoxicity, nausea, and vomiting. Furthermore the development of drug-resistant tumours is commonly observed following therapy with cisplatin. Hence there is a need for improved platinum derived drugs to overcome these limitations. Aims  Apoptosis contributes significantly to the cytotoxic effects of anticancer agents such as cisplatin; therefore in this study the potential anticancer properties of a series of pyrazole palladium(II) and platinum(II) complexes, [(3,5-R₂pz)₂PdCl₂] {R = H (1), R = Me (2)} and [(3,5-R₂pz)₂PtCl₂] {R = H (3), R = Me (4)}, were evaluated by assessment of their pro-apoptotic activity. Methods  The induction of apoptosis was measured in CHO cells by the detection of phosphatidylserine (PS) exposure using the annexin V and APOPercentage™ assays; DNA fragmentation using the Terminal deoxynucleotide transferase dUTP Nick End Labelling (TUNEL) assay; and the detection of activated caspase-3. Results  The platinum complexes were shown to be considerably more active than the palladium complexes, with complex 3 demonstrating the highest level of cytotoxic and pro-apoptotic activity. The LD₅₀ values for complex 3 and cisplatin were 20 and 70 μM, respectively, demonstrating that the cytotoxic activity for complex 3 was three times higher than for cisplatin. Various human cancer cell lines, including CaSki, HeLa, as well as the p53 mutant Jurkat T cell line were also shown to be susceptible to complex 3. Conclusions  Collectively, this in vitro study provides insights into action of palladium and platinum complexes and demonstrates the potential use of these compounds, and in particular complex 3, in the development of new anticancer agents.     

cis-Dichlorodiammine platinum (II) in the treatment of advanced colo-rectal cancer

The effect of CDDP was evaluated in 10 cases of advanced colo-rectal cancer. Prior chemotherapy was done in seven cases and three were fresh cases. The dosage of CDDP was in the range of 70-100 mg/m2 per individual. Seven cases out of 10 receiving the CDDP chemotherapy achieved no change and there were three cases of PD. Response rate was 0%. Values of serum creatinine and BUN were transiently evaluated and bone marrow toxicity was moderate. Emesis of patients treated with CDDP was suppressed by the administration of high doses of metoclopramide (2 mg/kg X 4 times).     

Synthesis and antitumor activity of a platinum (II)-doxorubicin complex

Summary A mixed platinum (II) complex with tert-butylamine and doxorubicin (cooordinated via the aminogroup) has been synthesized and tested for antitumor activity. The results indicate that the complex was active against doxorubibin-resistant P388 and cisplatin-resistant L1210 leukemias, while maintaining antitumor activity against sensitive parent lines.     

Diethyldithiocarbamate inhibition of murine bone marrow toxicity caused by cis-diamminedichloroplatinum(II) or diammine-(1,1-cyclobutanedicarboxylato)platinum(II)

We report here the effects of diethyldithiocarbamate (DDTC) rescue on myelotoxicity caused by carboplatin (CBDCA) and cisplatin (DDP) in C57BL/6 x DBA/2 F1 mice. All drugs were administered by injection into the tail vein. Myelotoxicity was assessed by WBC, bone marrow cellularity, and assays for pluripotent bone marrow stem cells (spleen colony forming unit) and granulocyte/macrophage progenitor cells (granulocyte/macrophage colony forming unit in culture). The most significant protection occurred in stem cells, where a single dose of DDTC (300 mg/kg) produced a platinum-drug dose modification factor of 3.3; i.e., the addition of DDTC reduced stem cell toxicity to the level produced by approximately one-third the dose of platinum drug alone. On a molar basis, DDP was 2.4 times as toxic to stem cells as CBDCA. The response of the stem cells to CBDCA and DDP was linear both with and without rescue, and the dose modification factor remained constant for doses of CBDCA up to 120 mg/kg and doses of DDP up to 15 mg/kg. Moreover, stem cell rescue appeared to be independent of DDTC dose (100-750 mg/kg) and time of administration (1.5 h before to 5 h after platinum drug). DDTC protection was less impressive for more mature hematological cells (granulocyte/macrophage colony forming units in culture). In studies of bone marrow cellularity, addition of DDTC (300 mg/kg) to DDP treatment (10 mg/kg) produced a 50% increase in the granulocyte-predominant cell population but had no effect on the lymphocyte population. Peripheral WBC showed no significant difference between rescued and unrescued groups and did not reflect the toxicity observed directly in the bone marrow.     

DNA binding of iproplatin and its divalent metabolitecis-dichloro-bis-isopropylamine platinum(II)

Summary The quadrivalent second-generation platinum complex iproplatin and an in vivo divalent metabolite of iproplatin,cis-dichloro-bis-isopropylamine platinum (CIP) were tested for binding to DNA in vitro. DNA binding was determined according to radioactivity measured using [¹⁴C]-iproplatin and [¹⁴C]-CIP and also by platinum content. Results indicate that (a) iproplatin shows negligible binding to DNA, (b) CIP binds to DNA in a time-dependent fashion, and (c) the isopropylamine ligand is intact when CIP is bound to DNA. Glutathione (GSH) inhibits the binding of CIP to DNA, possibly by inhibiting binding to DNA of the aquated form of CIP.