Status of new anthrapyrazole and pyrazoloacridine derivatives

Apoptosis-inducing activity of new pyrazole emodin derivatives in human hepatocellular carcinoma HepG2 cells

A series of new pyrazole derivatives from emodin synthesized in our lab have been shown to have much stronger cytotoxicity than emodin against various tumor cell lines. This study was to examine the apoptosis-inducing activity of these new emodin derivatives in human hepatocellular carcinoma HepG2 cell culture for a better understanding of their cytotoxic effects on the cancer cells. Several major events in the induction of cell apoptosis, nuclear chromatin condensation, DNA fragmentation, caspase-3 activation and poly ADP-ribose polymerase (PARP) cleavage were detected in the cells after treatment with the compounds at various concentrations. Of the seven emodin derivatives tested at a dose of 10 microM and within a treatment period of 24 h, only compounds 1 and 3 effectively induced all these apoptotic events in the cancer cells. The apoptosis-inducing activity of the compounds showed a positive correlation to their cytotoxic activity, suggesting a close connection between the growth inhibition and apoptosis induction of the cancer cells by these pyrazole emodin derivatives.

Design and synthesis of novel amino-substituted xanthenones and benzo[b]xanthenones: Evaluation of their antiproliferative activity and their ability to overcome multidrug resistance toward MES-SA/D×5 cells

A number of new xanthenone and benzo[b]xanthenone amino derivatives and their pyrazole-fused counterparts have been designed and synthesized possessing structural analogy to the potent anticancer agent 9-methoxypyrazoloacridine. The synthesis of the compounds proceeds through nucleophilic substitution of 1-chloro-4-nitroxanthenone or the corresponding benzo[b]xanthenone by the appropriately substituted amine or hydrazine, reduction of the nitro group, and conversion into the suitable dialkylaminoacetamides. This method cannot be applied for synthesis of the pyrazole-fused benzo[b]xanthenones, consequently a different, simple, and high-yielding synthetic procedure was developed for the preparation of the target molecules. In vitro cytotoxic potencies of the new derivatives toward the murine leukemia L1210 cell line, human colorectal adenocarcinoma (HT-29), and human uterine sarcoma (MES-SA and its 100-fold resistant to doxorubicin variant MES-SA/D x 5) cell lines are described and compared to those of reference drugs. The compounds exhibited significant cytotoxic activity against the tested cell lines and in addition they retain activity against the multidrug resistant MES-SA/D x 5 subline, showing resistant factors close to 1. A number of derivatives were found to possess DNA binding capacity, according to a standard ethidium bromide displacement assay. The majority of the studied compounds induce a G2/M arrest, although among them some G1 or S blockers have also been identified.

Design, synthesis, and antiproliferative activity of some novel aminosubstituted xanthenones, able to overcome multidrug resistance toward MES-SA/Dx5 cells

A series of novel xanthenone aminoderivatives and their pyrazole-fused counterparts possessing structural analogy to the potent anticancer agent 9-methoxypyrazoloacridine (PZA) reported. These compounds exhibited an interesting cytotoxic activity against a panel of cell lines. Most noticeably, they retain activity against the multidrug resistant MES-SA/Dx5 subline, showing resistant factors close to 1.

A phase II study of pyrazoloacridine in patients with advanced renal cell carcinoma

The aim of this study was to determine the antitumor activity of pyrazoloacridine in patients with renal cell carcinoma. Eligible patients had advanced renal cell carcinoma with bidimensionally measurable disease, a Karnofsky performance status of at least 70, life expectancy of greater than three months, no prior treatment with chemotherapy, and no evidence of brain metastases. Patients were treated intravenously with 750 mg/m2 every three weeks. Twelve patients were enrolled in this study and all were evaluable for response and toxicity. Of the twelve patients, no major responses were achieved. Toxicity was mild, with three patients requiring a 20% dose reduction. At the dose and schedule used in this trial, pyrazoloacridine is inactive in renal cell carcinoma.

Synthesis and antitumor evaluation of 2,5-disubstituted-indazolo[4, 3-gh]isoquinolin-6(2H)-ones (9-aza-anthrapyrazoles)

The synthesis and antitumor evaluation of 2, 5-disubstituted-indazolo[4,3-gh]isoquinolin-6(2H)-ones (9-aza-APs) are described. The key intermediates in the synthesis are benz[g]isoquinoline-5,10-diones which are substituted at positions 6 and 9 with groups of different nucleofugacity for SNAr displacements. The initial displacement of fluoride by a substituted hydrazine leads to the pyrazole analogues. Substitution of the remaining leaving group by an amine or BOC-protected amines leads to the 9-aza-APs 12. These analogues were converted into their maleate or hydrochloride salts 13. In two cases, namely, 13x and 13z, sidearm buildup was also employed in the synthetic pathway. In vitro evaluation of 9-aza-APs against the human colon tumor cell line LoVo uncovered for most of the compounds a cytotoxic potency lower than that of DuP-941 or mitoxantrone and comparable to that of doxorubicin. Only analogues 13c, 13n, and 13ff were as cytotoxic as DuP-941. Interestingly, while DuP-941 was highly cross-resistant in the LoVo cell line resistant to doxorubicin (LoVo/Dx), the 9-aza-APs carrying a distal lipophilic tertiary amine moiety in both chains were capable of overcoming the MDR resistance induced in this cell line. The 9-aza-APs show outstanding in vivo antitumor activity against both systemic P388 murine leukemia and MX-1 human mammary carcinoma transplanted in nude mice. At their optimal dosages, congeners 13a-c, 13f, 13n, 13q, 13x, and 13dd were highly effective against P388 leukemia with T/C% of 200-381, while the T/C% value of DuP-941 was 147. In the MX-1 tumor model, 24 compounds elicited percentages of tumor weight inhibitions (TWI) ranging from 50% to 99%. Congeners 13d, 13k, 13l, 13x, 13z, and 13ee emerged as the most effective ones, with TWI% 96, simliar to that of DuP-941 (TWI% = 95). On the basis of their efficacy profile in additional experimental tumors and lack of cardiotoxicity in preclinical models, two congeners have surfaced as potential clinical candidates.

Evaluation of pyrazoloacridine in patients with advanced pancreatic carcinoma

PURPOSE

Pyrazoloacridine (PZA) is an acridine derivative selected for clinical development because of broad pre-clinical antitumor activity and solid tumor selectivity. Phase I evaluations with PZA have demonstrated predictable toxicity and suggested clinical efficacy. A phase II trial in patients with previously untreated advanced pancreatic cancer was conducted.

METHODS

PZA was administered at a dose of 750 mg/m2 intravenously over 3 hours every 21 days. Seventeen patients were treated receiving a total of 46 courses of PZA.

RESULTS

Of the 15 patients evaluable for response, no responses were observed (0% response rate, 95% confidence interval 0-22%). Major toxicities directly attributable to PZA included moderate neutropenia and mild neurotoxicity.

CONCLUSION

PZA at this dose and schedule of administration was inactive in patients with pancreatic carcinoma.