Synthesis and antitumor activity of a series of [2-substituted-4,5-bis(aminomethyl)-1,3-dioxolane]platinum(II) complexes

Platinum(II) carboxylato complexes containing 7-azaindoles as N-donor carrier ligands showed cytotoxicity against cancer cell lines

The platinum(II) malonato (Mal) and decanoato (Dec) complexes of the general formulas [Pt(Mal)(naza)₂] (1-3) and cis-[Pt(Dec)₂(naza)₂] (4-7) were prepared, characterized and tested for their in vitro cytotoxicity against cisplatin-sensitive (A2780) and cisplatin-resistant (A2780R) human ovarian carcinoma cell lines and non-cancerous human lung fibroblasts (MRC-5); naza=halogeno-derivatives of 7-azaindole. Complexes 1-7 effectively overcome the acquired resistance of ovarian carcinoma cells to cisplatin. Complexes 2 (IC₅₀=26.6±8.9μM against A2780 and 28.9±6.7μM against A2780R), 4 (IC₅₀=14.5±0.6μM against A2780 and 14.5±3.8μM against A2780R) and 5 (IC₅₀=13.0±1.1μM against A2780 and 13.6±4.9μM against A2780R) indicated decreased toxicity against healthy MRC-5 cells (IC₅₀>50.0μM for 2 and >25.0μM for 4 and 5). The representative complexes 2 and 4 showed mutually different effect on the A2780 cell cycle at IC₅₀ concentrations after 24h exposure. Concretely, the complex 2 caused cell cycle arrest at G₀/G₁ phase, while 4 induced cell death by apoptosis with high population of cells in sub-G₁ cell cycle phase. The hydrolysis and interactions of the selected complexes with biomolecules (glutathione (GSH) and guanosine monophosphate (GMP)) were also studied by means of ¹H NMR and ESI+ mass spectra.

Reactivity of kiteplatin with S-donor biomolecules and nucleotides

Kiteplatin, (cis-1,4-DACH)dichloridoplatinum(ii), contains an isomeric form of the carrier ligand present in the successful antitumor drug oxaliplatin and has been recently found to be very active against oxaliplatin-resistant colon cancers, confirming that, by changing the nature of the amine ligand, it is possible to obtain platinum drugs that are not cross-resistant to those already in clinical use. Apart from interaction with DNA, another factor that can affect the activity of platinum drugs is their metabolic fate in the cellular environment. Therefore, kiteplatin has been reacted with S-donor biomolecules, such as glutathione, cysteine, and methionine. The investigation has further confirmed the different reactivity of methionine as compared to cysteine-containing peptides and has unraveled the possibility of cis-1,4-DACH to become mono-coordinated with one free end (a situation never seen for isomeric 1,2-DACH ligands) and to labilize cis ligands as a consequence of its large steric hindrance. The reaction of kiteplatin-GSH adducts with 5'-GMP has also shown how the reaction products can be different depending upon the aerobic or anaerobic reaction conditions used.

Synthesis, in-vitro cytotoxic activity and DNA interactions of new dicarboxylatoplatinum(II) complexes with 2-hydroxymethylbenzimidazole as carrier ligands

Objectives

The aim of this study was to investigate the in-vitro cytotoxic activity of new platinum(II) complexes on the human HeLa (ER−), MCF-7 (ER+) and MDA-MB 231 (ER−) cell lines. Furthermore, we investigated plasmid DNA interactions and inhibition of BamHI and HindIII restriction enzyme activity of the complex 1–4,7.

Methods

Platinum(II) complexes were synthesised from precursor complexes of [PtL2Cl2] and [PtL2I2]. Their cytotoxic activity was tested by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Their plasmid DNA interactions and restriction enzyme activities were also investigated using the agarose gel electrophoresis method.

Key findings

The growth inhibitory effect results showed that the cytotoxicity of complex 2 was found to be the most active complex among the synthesised complexes.

Conclusions

The MTT results showed that complex 2 was found to be cytotoxic equal to cisplatin and higher than carboplatin against the MCF-7 and MDA-MB-231 cell lines. Furthermore, the estrogen or progesterone co-treatment slightly increased the cytotoxicity of complex 2, the cisplatin and carboplatin compared with the complex 2 tested alone in 50 μm concentration. According to plasmid DNA interaction and the restriction studies, complexes 1–4,7 modified the tertiary structure of pBR322 plasmid DNA, and complexes 2–4 prevented enzyme digestion at high concentrations.

Synthesis, characterization and in vitro antitumor activity of platinum(II) oxalato complexes involving 7-azaindole derivatives as coligands

The platinum(II) oxalato complexes [Pt(ox)(naza)2] (1-3) were synthesized and characterized by elemental analysis (C, H, N), multinuclear NMR spectroscopy ((1)H, (13)C, (15)N, (195)Pt) and electrospray ionization mass spectrometry (ESI-MS); naza = 4-chloro-7-azaindole (4Claza; 1), 3-bromo-7-azaindole (3Braza; 2) or 4-bromo-7-azaindole (4Braza; 3). The prepared substances were screened for their in vitro antitumor activity on the osteosarcoma (HOS) and breast adenocarcinoma (MCF7) human cancer cell lines, where 2 showed moderate antitumor effect (IC50 = 27.5 μM, and 18.3 μM, respectively). The complex 2 was further tested on a panel of six others human cancer cell lines, including the malignant melanoma (G361), cervix carcinoma (HeLa), ovarian carcinoma (A2780), cisplatin-resistant ovarian carcinoma (A2780R), lung carcinoma (A549) and prostate adenocarcinoma (LNCaP). This substance was found to be moderate antitumor effective against G361 (IC50 = 17.3 μM), HeLa (IC50 = 31.8 μM) and A2780 (IC50 = 19.2 μM) cell lines. The complex 2 was also studied by NMR for its solution stability and by ESI-MS experiments for its ability to interact with biomolecules, such as cysteine, glutathione or guanosine 5'-monophosphate.

Synthesis, anticancer activity and toxicity of a water-soluble 4S,5S-derivative of heptaplatin, cis-{Pt(II)[(4S,5S)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]·(3-hydroxyl-cyclobutane-1,1-dicarboxylate)}

A water-soluble 4S,5S-derivative of heptaplatin, cis-{Pt(II)[(4S,5S)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolane]·(3-hydroxyl-cyclobutane-1,1-dicarboxylate)} was synthesized. The anticancer activity and toxicity were evaluated by comparing its interaction with DNA, cytotoxicity against four human cancer cell lines, antitumor efficiency in human gastric carcinoma NCI-N87 xenografts in nude mice, and preliminary side-effects in rats to those of its 4R,5R-optical isomer which is under preclinical development. Both isomers induce condensation of DNA to the same extent and have similar cytotoxicity, but show different antitumor activity and toxicity, probably owing to the difference in respective pharmacokinetic profiles. 4S,5S-Isomer seems to exhibit superior antitumor activity and less toxicity than 4R,5R-optical isomer as well as the parent heptaplatin. These results imply that 4S,5S-configuration as a new drug candidate may be better than 4R,5R-counterpart.

The status of platinum anticancer drugs in the clinic and in clinical trials

Since its approval in 1979 cisplatin has become an important component in chemotherapy regimes for the treatment of ovarian, testicular, lung and bladder cancers, as well as lymphomas, myelomas and melanoma. Unfortunately its continued use is greatly limited by severe dose limiting side effects and intrinsic or acquired drug resistance. Over the last 30 years, 23 other platinum-based drugs have entered clinical trials with only two (carboplatin and oxaliplatin) of these gaining international marketing approval, and another three (nedaplatin, lobaplatin and heptaplatin) gaining approval in individual nations. During this time there have been more failures than successes with the development of 14 drugs being halted during clinical trials. Currently there are four drugs in the various phases of clinical trial (satraplatin, picoplatin, Lipoplatin and ProLindac). No new small molecule platinum drug has entered clinical trials since 1999 which is representative of a shift in focus away from drug design and towards drug delivery in the last decade. In this perspective article we update the status of platinum anticancer drugs currently approved for use, those undergoing clinical trials and those discontinued during clinical trials, and discuss the results in the context of where we believe the field will develop over the next decade.

(4S,5S)-2-(3-Methoxy-phen-yl)-1,3-dioxolane-4,5-dicarboxamide

In the title compound, C(12)H(14)N(2)O(5), the five-membered ring adopts an envelope conformation. In the crystal structure, inter-molecular N-H⋯O inter-actions link the mol-ecules into a three-dimensional network. A weak C-H⋯π inter-action is also found.

(4S,5S)-2-(4-Chloro-phen-yl)-1,3-dioxolane-4,5-dicarboxamide

The title compound, C₁₁H₁₁ClN₂O₄, is an important inter­mediate for the preparation of platinum anti­cancer drugs. The dioxolane ring adopts a twist conformation with an equatorially attached chloro­phenyl substituent. In the crystal structure, mol­ecules are linked into a two-dimensional network parallel to (001) by N—H⋯O and C—H⋯O hydrogen bonds.

Randomized, multicenter, phase III trial of heptaplatin 1-hour infusion and 5-fluorouracil combination chemotherapy comparing with cisplatin and 5-fluorouracil combination chemotherapy in patients with advanced gastric cancer

PURPOSE

Heptaplatin (Sunpla) is a cisplatin derivative. A phase IIb trial using heptaplatin resulted in a 34% response rate with mild nephrotoxicity. We conducted a randomized phase III trial of heptaplatin plus 5-FU compared with cisplatin plus 5-FU in patients with advanced gastric cancer.

MATERIALS AND METHODS

One hundred seventy-four patients (heptaplatin, n=88; cisplatin, n=86) from 13 centers were enrolled. The eligibility criteria were as follows: patients with pathologically-proven adenocarcinoma, chemonaive patients, or patients who had received only single adjuvant chemotherapy, and who had a measurable or evaluable lesion. On day 1, heptaplatin (400 mg/m(2)) or cisplatin (60 mg/m(2)) was given over 1 hour with 5-FU (1 gm/m(2)) on days 1~5 every 4 weeks.

RESULTS

At the time of survival analysis, the median overall survival was 7.3 months in the 5-FU + heptaplatin (FH) arm and 7.9 months in the 5-FU + cisplatin (FP) arm (p=0.24). Of the FH patients, 34.2% (complete response [CR], 1.3%; partial response [PR], 32.9%) experienced a confirmed objective response compared with 35.9% (CR 0%, PR 35.9%) of FP patients (p=0.78). The median-time-to-progression was 2.5 months in the FH arm and 2.3 months in the FP arm. The incidence of neutropenia was higher with FP (28%) than with FH (16%; p=0.06); grade 3~4 nausea and vomiting were more frequent in the FP than in the FH arm (p=0.01 and p=0.05, respectively). The incidence of increased proteinuria and creatininemia was higher with FH than with FP; however, there was no statistical difference. There were no treatment-related deaths.

CONCLUSION

Heptaplatin showed similar effects to cisplatin when combined with 5-FU in advanced gastric cancer patients with tolerable toxicities.

(4S,5S)-2-(2-Bromo-phen-yl)-1,3-dioxolane-4,5-dicarboxamide

The asymmetric unit of the title compound, C₁₁H₁₁BrN₂O₄, contains two crystallographically independent mol­ecules in which the bromo­phenyl rings are oriented at dihedral angles of 39.28 (3)°. The dioxolane rings adopt envelope conformations. Intra­molecular N—H⋯O hydrogen bonds result in the formation of four five-membered rings, having planar and envelope conformations. In the crystal structure, inter­molecular N—H⋯O hydrogen bonds link mol­ecules into chains along the b axis, forming R₂²(8) ring motifs.

(4S,5S)-2-(2-Thien-yl)-1,3-dioxolane-4,5-dicarboxamide

In the title compound, C(9)H(10)N(2)O(4)S, which is an important inter-mediate for the preparation of anti-tumor platinum drugs, the dioxolane ring adopts an envelope conformation with the C atom bonded to the thienyl ring at the flap position. Intra-molecular N-H⋯O and C-H⋯O hydrogen bonds result in the formation of two five-membered rings having envelope conformations. In the crystal structure, inter-molecular N-H⋯O and C-H⋯O hydrogen bonds link the mol-ecules into a three-dimensional network.

(4S,5S)-2-(2-Fluoro-phen-yl)-1,3-dioxolane-4,5-dicarboxamide

In the mol-ecule of the title compound, C(11)H(11)FN(2)O(4), the five-membered ring adopts an envelope conformation. An intra-molecular N-H⋯F hydrogen bond occurs. In the crystal structure, inter-molecular N-H⋯O hydrogen bonds link the mol-ecules.

Synthesis, DNA interaction and cytotoxicity studies of cis-{[1, 2-bis(aminomethyl)cyclohexane]dihalo}platinum(II) complexes

A series of platinum compounds with an analogue structure to cisplatin have been synthesized and their biological activity against HL-60 cancer cell line has been studied. The interaction with DNA was evaluated by circular dichroism (CD), electrophoresis and atomic force microscopy (AFM) techniques showing slight but significant structure-dependent differences among the evaluated complexes. The cytotoxicity assays afforded interesting relationships between the structure and the biological activity, thus, a better antiproliferative activity was observed for the complexes with higher hydrophobicity: the methoxylated complexes showed better activity than the hydroxylated ones (17versus20 and 19versus21). Especially compound 22 having a fatty acid subunit presented a promising cytotoxic activity. On the other hand, dichloro complexes 12 and 13 had better activities than the diiodo complexes, probably due to their better metabolic stability. Between both dichloro complexes the aromatic one showed much higher activity, which could be rationalized on the basis of the intercalating ability of the benzene ring. The flow cytometry assays indicated that most of the complexes induced the cell death by apoptosis except for aromatic compound 12 and the lipophilic compound 22 that induced preferably a mechanism of necrosis.

Anti-tumor activity of heptaplatin in combination with 5-fluorouracil or paclitaxel against human head and neck cancer cells in vitro

Heptaplatin (HTP), a newly developed platinum analog, has been approved for the treatment of gastric cancers in South Korea. In this study we explored the potential of HTP for the treatment of head and neck squamous cell cancers (HNSCC). The anti-proliferative activity of HTP was evaluated in FaDu, a human HNSCC cell line. Combinations of HTP with 5-fluorouracil (5-FU) or paclitaxel (PTX) were determined using combination indexes, and were compared with combinations of cisplatin and 5-FU or PTX. In order to evaluate the transport of HTP into tumor tissue, its penetration through multicell layers (MCLs) of cancer cells was measured. Cisplatin+5-FU and HTP+5-FU showed additive to antagonistic interactions. In terms of the HTP+paclitaxel combination, HTP showed antagonism and additivity at the 50 and 80% growth inhibition levels, respectively. An additive interaction was obtained and apoptosis was increased by 2-fold at both inhibition levels when the combinatorial PTX dose was reduced to 1/10. HTP, but not cisplatin or oxaliplatin (L-OHP), maintained its anti-proliferative activity after MCL penetration at clinically relevant concentrations, which can be attributed to lower protein binding of HTP. In conclusion, the present study suggests that low-dose PTX may sensitize tumor cells to HTP. HTP also showed greater penetration through multilayers of tumor cells compared to cisplatin and L-OHP, which may be an important characteristic for solid tumor treatment. Overall, the present study supports the clinical development of HTP in combination with low-dose PTX against HNSCC.

Synthesis and in vitro cytotoxicity of novel hydrophilic chiral 2-alkoxy-1,4-butanediamine platinum (II) complexes

Twenty-six new hydrophilic chiral 2-alkoxy-1,4-butanediamine platinum (II) complexes having a seven-membered ring structure between a bidentate carrier ligand and a platinum atom have been synthesized and most of them were evaluated for their in vitro cytotoxicity toward A549 human non-small cell lung carcinoma and HCT-116 human colon cancer cell lines. The cytotoxicities of platinum complexes are related to the nature of the carrier ligand and leaving group. Complex 5'b, viz. cis-dichloro[(2R)-ethoxy-1,4-butanediamine] platinum (II), exhibits the greatest potency among those 21 tested platinum complexes in both cell lines.

Potential new antitumor agents from an innovative combination of camphorato, a ramification of traditional Chinese medicine, with a platinum moiety

Eight new camphorato platinum complexes have been synthesized and evaluated for their in vitro cytotoxicity against HL-60 human leukemia, 3AO human ovarian carcinoma, BEL-7402 human hepatocarcinoma, and A549 human lung carcinoma cell lines. Most complexes showed good cytotoxic activity against the above-selected cell lines. Among the complexes, two compounds were assayed for their in vivo antitumor activity against LS-174T human colon carcinoma cells implanted in mice. One complex exhibited not only higher in vivo antitumor activity, but also less toxicity than oxaliplatin when it was administered intravenously at a dose of 6 mg/kg three times.

Asymmetric Hydrogenation of Isobutyrophenone Using a [(Diphosphine) RuCl2 (1,4-Diamine)] Catalyst

[reaction: see text] The use of three chiral 1,4-diamines in the [(diphosphine) RuCl(2) (diamine)] catalyst system is demonstrated in the hydrogenation of acetophenone. The use of a 1,4-diamine offers unique properties that allow tuning of the catalyst system. These include the first example of the use of a racemic diamine in combination with a chiral phosphine, which gives 95% ee in the hydrogenation of isobutyrophenone.

Biology of SNU cell lines

SNU (Seoul National University) cell lines have been established from Korean cancer patients since 1982. Of these 109 cell lines have been characterized and reported, i.e., 17 colorectal carcinoma, 12 hepatocellular carcinoma, 11 gastric carcinoma, 12 uterine cervical carcinoma, 17 B-lymphoblastoid cell lines derived from cancer patients, 5 ovarian carcinoma, 3 malignant mixed Mllerian tumor, 6 laryngeal squamous cell carcinoma, 7 renal cell carcinoma, 9 brain tumor, 6 biliary tract, and 4 pancreatic carcinoma cell lines. These SNU cell lines have been distributed to biomedical researchers domestic and worldwide through the KCLB (Korean Cell Line Bank), and have proven to be of value in various scientific research fields. The characteristics of these cell lines have been reported in over 180 international journals by our laboratory and by many other researchers from 1987. In this paper, the cellular and molecular characteristics of SNU human cancer cell lines are summarized according to their genetic and epigenetic alterations and functional analysis.

Molecular mechanisms of heptaplatin effective against cisplatin-resistant cancer cell lines: less involvement of metallothionein

Background

Heptaplatin is a new platinum derivative with anticancer activity against various cancer cell lines, including cisplatin-resistant cancer cell lines (Cancer Chemother Pharmacol 1995; 35: 441).

Methods

Molecular mechanisms of heptaplatin effective against cisplatin-resistant cancer cell lines has been investigated in connection with metallothionein (MT). Cytotoxicity was determined by an MTT assay. MT mRNA, was determined by RT-PCR assay. Transfection study was carried out to examine the function of MT.

Results

Of various gastric cancer cell lines, SNU-638 and SNU-601 showed the highest and lowest levels of MT mRNA, respectively, showing 80-fold difference. The IC₅₀ values of SNU-638 to cisplatin, carboplatin and heptaplatin were 11.2-fold, 5.1-fold and 2.0-fold greater than those of SNU-601, respectively. Heptaplatin was more effective against cisplatin-resistant and MT-transfected gastric cancer sublines than cisplatin or carboplatin was. In addition, heptaplatin attenuated cadmium, but not zinc, induction of MT.

Conclusion

These results indicate that molecular mechanisms of heptaplatin effective against cisplatin-resistant gastric cancer sublines is at least in part due to the less involvement of MT in heptaplatin resistance as well as its attenuation of MT induction.

4′-α-C-Branched N,O-nucleosides: synthesis and biological properties

The synthesis of 4'-alpha-C-branched N,O-nucleosides has been described, based on the 1,3-dipolar cycloaddition of nitrones with vinyl acetate followed by coupling with silylated nucleobases, The obtained compounds have been evaluated for their activity against HSV-1, HSV-2, HTLV-1. Cytotoxicity and apoptotic activity have been also investigated: compound 10c shows moderate apoptotic activity in Molt-3 cells.

Combination chemotherapy with 5-fluorouracil and heptaplatin as first-line treatment in patients with advanced gastric cancer

Heptaplatin is a recently developed platinum derivative. This agent has been reported to have a response rate of 17% as a single agent, and tolerable toxicity in the treatment of advanced gastric cancer. The aim of this study was to evaluate the efficacy and toxicity of a combination of 5-fluorouracil (5-FU) and heptaplatin in patients with advanced gastric cancer. Forty-seven chemotherapy-naive patients with advanced or recurred gastric cancer were recruited. 5-FU was administered over 120 hr by continuous intravenous infusion from day 1 to 5, at a daily dose of 1,000 mg/m2 and heptaplatin was administered over 1 hr by intravenous infusion on day 1 at 400 mg/m2, and this cycle was repeated every 4 weeks. The response rate was 21%, median progression-free survival was 1.9 months (95% CI, 1.6 to 2.2 months). Median overall survival was 6.2 months (95% CI, 4 to 8.4 months) and the 1-yr survival rate was 29% for all patients. The most frequent toxicity was proteinuria. Toxicities were generally mild and reversible. This study demonstrates that the combination of 5-FU/heptaplatin combination is less active but tolerated in patients with advance gastric cancer.

A Phase I study of cis-malonato[(4R,5R)-4,5-bis(aminomethyl)-1,3-dioxolane] platinum(II) in patients with advanced malignancies

BACKGROUND

A Phase I study of cis-malonato[(4R,5R)-4,5-bis(aminomethyl)-1,3-dioxolane] platinum(II) (SKI 2053R), a new platinum derivative, was performed to determine the maximum tolerated dose (MTD), the dose limiting toxicities (DLTs), and the pharmacokinetic profile of SKI 2053R in patients with advanced, refractory malignancies.

METHODS

Twenty-one patients were entered into the study. SKI 2053R was administered with an intravenous infusion over 1 hour every 4 weeks. The SKI 2053R dose was escalated from 40 mg/m(2) up to 480 mg/m(2) using a modified Fibonacci scheme. Pharmacokinetic analysis was done in all patients to determine the total and ultrafiltrable platinum concentrations in both the plasma and the urine.

RESULTS

All patients were evaluable for toxicity and response. There was no significant toxicity with dosages up to 360 mg/m(2). At 480 mg/m(2), two of three patients developed Grade 4 hepatotoxicity, Grade 3 leukopenia and thrombocytopenia, and Grade 2 azotemia and proteinuria. Other toxicity included nausea and emesis, but it was controlled with antiemetics. SKI 2053R did not cause significant neurotoxicity or mucositis. There were 4 patients with stable disease among the 21 patients. Plasma decay of the total and free platinum concentrations was best fitted by using a two-compartment, open model. The terminal plasma half-life of the total platinum after SKI 2053R administration ranged from 63.4 hours to 114.1 hours in dosages ranging from 40 mg/m(2) to 480 mg/m(2) without significant dose dependency. However, the terminal plasma half-life of the free platinum concentration showed a significant dose dependent, incremental pattern. The renal excretion of SKI 2053R measured as platinum ranged from 49% to 75% of the administered dose.

CONCLUSIONS

The MTD of SKI 2053R was 480 mg/m(2). The major DLTs were hepatotoxicity, nephrotoxicity, and myelosuppression. The recommended starting dose for a subsequent Phase II study is 360 mg/m(2) once every 4 weeks.

Phase II clinical trial of SKI-2053R, a new platinum analog, in the treatment of patients with advanced gastric adenocarcinoma

BACKGROUND

SKI-2053R (SK Chemicals, Kyungki-Do, South Korea) is a new platinum derivative with antitumor activity against various cell lines, including cisplatin-resistant tumor cell lines. Preclinical studies have suggested that it is less nephrotoxic than cisplatin. This study evaluated the efficacy and toxicity of SKI-2053R in the treatment of patients with advanced gastric adenocarcinoma.

METHODS

Thirty-seven patients with advanced gastric adenocarcinoma that was unresectable or metastatic were treated. No prior chemotherapy or radiotherapy was allowed. Patients received SKI-2053R 360 mg/m(2) by 1-hour infusion on Day 1. After the first cycle, subsequent doses were adjusted according to the toxicity. Courses were repeated every 28 days.

RESULTS

Thirty-five patients were evaluable for response and toxicity. Six patients achieved a major response (17%; 95% confidence interval, 8-33%); 2 were complete and 4 were partial responses. The median duration of response was 7.2 months, with a range of 1-20 months. Patients could tolerate the treatment without significant toxicity. No patients had Grade 3 or 4 toxicity. The most frequent toxicity was Grade 1 or 2 proteinuria (26% of cycles), but it was mild and transient. Leukopenia, thrombocytopenia, azotemia, nausea and vomiting, and neurotoxicity were not frequent. These low toxicity profiles indicated that the dose of SKI-2053R could be increased in future studies.

CONCLUSIONS

SKI-2053R was active in the treatment of patients with gastric adenocarcinoma and had favorable toxicity profiles.

Phase II trial of a novel platinum analog, SKI 2053R, in patients with previously untreated extensive-stage small-cell lung cancer

A phase II trial of a novel platinum analog, SKI 2053R, was performed in patients with previously untreated extensive-stage disease (ED) small-cell lung cancer (SCLC). SKI 2053R was administered at the dose of 400 mg/m2 every 3 to 4 weeks as a 1-h infusion. After the first cycle, the dose was escalated to 440 mg/m2 based on toxicity. Thirty-eight patients (31 male) were enrolled between June 1995 and August 1997. The median age was 61 years (range, 36-70 years). Six of 37 evaluable patients achieved a partial response (16.2%; 95% confidence interval [CI], 4.4-28.0%). The durations of response were 1.1, 1.5, 1.7, 1.9, 3.4, and 4.6 months. The estimated median survival time was 7.4 months (95% CI, 5.1-9.7 months). Grade 3 or 4 toxicities were not observed. Grade 1 to 2 leukopenia, anemia, and thrombocytopenia were seen in 5 of 68 cycles, 16 of 68, and 2 of 68, respectively. Nonhematologic toxicities included grade 1 to 2 nausea or vomiting (30 of 68 cycles), nephrotoxicity (27 of 68), and hepatotoxicity (13 of 68). SKI 2053R showed a modest antitumor activity with limited toxicities in patients with ED SCLC. Further clinical trials are warranted in SCLC with a higher dose of SKI 2053R.

Embryotoxic effects of SKI 2053R, a new potential anticancer agent, in rats

SKI 2053R, cis-malonato[(4R,5R)-4,5-bis(aminomethyl)-2-isopropyl-1,3-dioxolan e] platinum(II), is a newly developed antitumor platinum complex derived from cisplatin. Preclinical studies suggest that it may have greater antitumor activity and lower toxicity than cisplatin. The potential of SKI 2053R to induce embryotoxicity was investigated in the Sprague-Dawley rat. One hundred mated rats (sperm in vaginal lavage = Day 0) were distributed among three treated groups and a control group. SKI 2053R was administered intravenously to pregnant rats from Days 6 to 16 of gestation at dose levels of 0, 0.75, 1.5, and 3.0 mg/kg/d. All dams were subjected to caesarean section on Day 20 of gestation. At 3 mg/kg, reduced food intake, reduced body weight, and decreased liver weight were observed in dams. An increase in the resorption rate and a reduction in the fetal weight were also found. In addition, various types of visceral and skeletal malformations occurred at an incidence of 18.5 and 6.0%, respectively. Characteristic malformations included dilated cerebral ventricle, anophthalmia, microphthalmia, fused or absent cervical arch, fused thoracic arch, fused thoracic centrum, and fused rib, among others. Delayed ossification of both sternebrae and metatarsals was also observed. There were no signs of maternal toxicity or embryotoxicity at 0.75 and 1.5 mg/kg. The results show that SKI 2053R is embryotoxic at a minimally maternally toxic dose in rats.