[Anthracycline antibiotics and their derivatives--inhibitors of topoisomerase I].

The relationship between the structure of new semisynthetic derivatives of doxorubicin, daunorubicin, and carminomycin and their ability to inhibit topoisomerase 1 were studied. The new derivatives inhibit the activity of topoisomerase 1 at low concentrations, induce the death of K-562 leukemia cells in culture, and produce an antitumor effect in experimental animals with P388 leukemia.

Altered expression of topoisomerase IIalpha contributes to cross-resistant to etoposide K562/MX2 cell line by aberrant methylation.

KRN 8602 (MX2) is a novel morpholino anthracycline derivative having the chemical structure 3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin hydrochloride. To investigate the mechanisms of resistance to MX2, we established an MX2-resistant phenotype (K562/MX2) of the human myelogeneous leukaemia cell line (K562/P), by continuously exposing a suspension culture to increasing concentrations of MX2. K562/MX2 cells were more resistant to MX2 than the parent cells, and also showed cross-resistance to etoposide and doxorubicin. Topoisomerase (Topo) IIalpha protein levels in K562/MX2 cells were lower of those in K562/P cells on immunoblot analysis and decreased expression of Topo IIalpha mRNA was seen in K562/MX2 cells. Topoisomerase II catalytic activity was also reduced in the nuclear extracts from K562/MX2 cells when compared with K562/P cells. Aberrant methylated CpG of Topo IIalpha gene was observed in K562/MX2 cells when compared with the parent line on methylation-specific restriction enzyme analysis. To overcome the drug resistance to MX2 and etoposide, we investigated treatment with 5-Aza-2'-deoxycytidine (5AZ), which is a demethylating agent, in K562/MX2 cells. 5-Aza-2'-deoxycytidine treatment increased Topo IIalpha mRNA expression in K562/MX2 cells, but not in K562/P cells, and increased the cytotoxicity of MX2 and etoposide. Methylated CpG was decreased in K562/MX2 cells after 5AZ treatment. We concluded that the mechanism of drug resistance to MX2 and etoposide in K562/MX2 cells might be the combination of decreased expression of Topo IIalpha gene and increased methylation, and that 5AZ could prove to be a novel treatment for etoposide-resistant cell lines, such as K562/MX2.

Carminomycin, 14-hydroxycarminomycin and its novel carbohydrate derivatives potently kill human tumor cells and their multidrug resistant variants.

The new hydrophilic derivatives of 14-hydroxycarminomycin were obtained using 13-dimethyl ketal of 14-bromocarminomycin (6) as the starting compound. The reductive alkylation of 6 with melibiose or D-galactose followed by hydrolysis of the corresponding intermediate bromoketals 9 and 11 produced 3'-N-[-alpha-D-(galactopyranosyl-(1 --> 6)-O-D-1-desoxyglucit-1-yl]-14-hydroxycarminomycin (10) and 3'-N-(1-desoxy-D-galactit-1-yl)-14-hydroxycarminomycin (12), respectively. These novel derivatives 10 and 12 were less toxic than carminomycin or 14-hydroxycarminomycin for leukemia (K562) and breast carcinoma (MCF-7) cells. Importantly, carminomycin, 14-hydroxycarminomycin and compounds 10 and 12 were similarly active for wild type cells and their multidrug resistant (MDR) sublines, K562i/S9 and MCF-7Dox.

New TFO conjugates containing a carminomycinone-derived chromophore.

Conjugates obtained by linking the anthracycline intercalating chromophore to triple helix forming oligonucleotides (TFOs) have been used in a physicochemical study of the stability of triple helices with DNA sequences of pharmacological relevance. The intercalating moiety is represented by carminomycinone derivatives obtained upon O-demethylation and hydrolysis of the glycosidic linkage of daunomycin followed by the introduction of an alkylating residue at two different positions. Results of experiments with a polypurinic region present in the multidrug resistance (MDR) gene indicate that the stability of the triple helix is significantly enhanced by replacement of C's with (5-Me)C's in the TFO sequences tested. The stability is not changed when a 3'-TpT is present in place of a 3'-CpG at the presumed intercalation site of the anthraquinone chromophore. The same carminomycinone derivatives were used for the preparation of conjugates able to form triple helices with the polypurine tract (PPT) present in the human integrated genome of HIV-1 infected cells. Three different TFOs (T(4)(Me)CT(4)(Me)CC, C2; T(4)(Me)CT(4)(Me)CC(Me)CC(Me)CCT, C6; and T(4)(Me)CT(4)G(6), G6) were designed and linked to the anthraquinone moiety. These conjugates showed a significantly enhanced ability to bind the PPT region of HIV with respect to the nonconjugated TFOs.

Intrathecal chemotherapy with MX2 for treating glioma dissemination in vivo.

We examined whether the intrathecal MX2 chemotherapy for treating dissemination of malignant glioma would be a feasible therapy. In the toxicity study, physiological and histological neurotoxicity was not observed in the rats treated with less than 100 microg/kg of MX2 administered intracisternally. But physiological side effects were observed in the treatment group of more than 200 microg/kg and histological brain toxicity was in the treatment group of more than 1000 microg/kg. Dissemination models were induced in rats by intracisternal inoculation of C6 glioma cells. The median survival times of the rats treated with 100 microg/kg of intrathecal MX2 on day 1, 3, or 7 after tumor inoculation were prolonged by 52.4% (p = 0.0006), 31.5% (p = 0.0007), and 7.1% (p = 0.0180), respectively, compared to that of untreated control animals. Intrathecal MX2 treatment also cured 33.6% of rats in the treatment group. These findings suggested that there was a possibility that intrathecal MX2 would be a safe and effective method for treating dissemination of malignant glioma.

Phase II trial of pre-irradiation KRN8602 (MX2) in malignant glioma patients.

KRN8602 (MX2) is a newly developed morpholino anthracycline that crosses the blood-brain barrier where it becomes distributed in brain tissue after intravenous administration. This morpholino anthracycline has been found to be effective against human glioma cells and the intracerebrally transplanted tumors in vivo, We performed a phase II trial using KRN8602 as a single agent in malignant glioma patients who had not received prior adjuvant therapy. The 13 patients (5 glioblastomas, 7 anaplastic astrocytomas and 1 malignant oligodendroglioma) enrolled received at least 1 cycle of KRN8602 at 35 mg/m2/day in 3-4 week intervals by intravenous bolus. Ten of these patients could be evaluated for response, and 13 for toxicity. Three patients (1 glioblastoma and 2 anaplastic astrocytomas) demonstrated a complete response (3/10, 30%). Concerning side effects, myelosuppression was moderately severe, with 30.7% of patients developing grade 3 leukopenia. Severe nausea/vomiting was observed in 69% of the patients, however, cardiotoxicity was not observed. The results indicate that KRN8602 demonstrated modest activity against malignant glioma with relatively severe, but manageable toxicity. Further assessment of the efficacy and toxicity of KRN8602 against malignant glioma may be worthwhile.

Antitumor activity of alpha fetoprotein and epidermal growth factor conjugates in vitro and in vivo.

Conjugates of carminomycin (Cm) with alpha-fetoprotein (AFP) and epidermal growth factor (EGF) were prepared and their cytotoxic activities were studied in vitro. Both conjugates showed cytotoxic activity which exceeded that of free Cm in tumor cell cultures of MCF-7, SKOV3, QOS, P388 and B16 cells. The antitumor effects of the conjugates were studied in vivo in mice with subcutaneous tumors of B16 and P388 cells. The Cm-AFP and Cm-EGF conjugates inhibited tumor growth and noticeably increased the mean life span in experimental animals. Our results suggest that the therapeutic activity of Cm can be significantly enhanced by conjugation to AFP or EGF.

New drugs in recurrent high grade gliomas.

BACKGROUND: The incidence of Central Nervous System (CNS) neoplasias ranges from 3.8 to 5.1 cases per 100,000 inhabitants. In the presence of recurrence, the treatment is problematic; chemotherapy is experimental, primarily because the response is palliative and of limited duration. MATERIALS AND METHODS: This article analyzes the new drugs that have been introduced for the treatment of these patients in recent years, the objective response, the TTP and the MST. RESULTS: The most encouraging results to date come from studies of temozolomide, which is one of the most active and best tolerated drugs in recent years. CONCLUSION: New approaches to chemotherapy treatment are necessary. Enrollment of patients into rigorous, well-conducted, clinical trials, both at tumor diagnosis and after tumor recurrence, will generate new information regarding investigational therapies and may offer improved therapies for patients with malignant gliomas.

An investigation of the cytotoxicity of the morpholino anthracycline MX2 against glioma cells in vitro.

MX2 is a novel morpholino anthracycline reported to have lower systemic toxicity than other anthracyclines. It has similar antitumour activity to adriamycin and is cytotoxic towards multi-drug resistant cells and anthracycline sensitive sublines of human and murine tumour cells. In this study MX2 showed a marked cytocidal effect compared to M2, the most cytotoxically active metabolite, and the nitrosourea, BCNU, when 30 ng/ml of each drug was added to separate flasks of C6 glioma cells grown in monolayer. The colony formation of C6 glioma cells was markedly inhibited by MX2 in a dose dependent manner. The LD50 values for MX2, M2 and BCNU were 10.5 ng/ml, 15.8 ng/ml and 465 ng/ml respectively. MX2 is likely to be bound to the main plasma protein, albumin, and can also interact with the plasma lipoproteins, particularly high density lipoprotein. The results in this study strongly support the further investigation of MX2 as a potential chemotherapeutic agent against brain tumours.

Antitumor effect and peritumoral brain edema formation in relation to MX2, ACNU, and doxorubicin therapy: a comparative analysis using rodent models of gliomas.

The potential antitumor effect of MX2, a new lipophilic morpholino anthracycline, was compared with those of ACNU or doxorubicin (DOX) using two different rodent glioma models. A mouse subcutaneous glioma model (203 glioma) was used to measure the effect of each drug on reducing the glioma size and a rat 9L intracerebral glioma model (9L glioma) was used to assess the antitumor effect on survival rate in a clinically similar fashion. Treatment with ACNU inhibited tumor growth by 94.6% (p < 0.0001) and complete regression of the tumor was observed in 3 of 25 (12.0%) of the ACNU-treated cases. Tumor growth was inhibited by 32.4% with DOX despite a tendency (p < 0.16) and by 59.4% with MX-2 (p < 0.001); neither of these drugs resulted in complete tumor regression. In the intracerebral glioma rats, only ACNU tended to ameliorate survival rate, but there was no statistical significance. These results suggest that ACNU has the most potent effect but MX2 can be an option for chemotherapy of malignant gliomas. Interestingly, all three drugs significantly elevated the brain water content on both the ipsilateral and contralateral sides of the tumor, although they did not induce brain edema in the normal rat brains. Careful management of brain edema might be required regardless of the drug used during chemotherapy to maximize the prognosis of glioma patients.

KRN8602 (MX2-hydrochloride): an active new agent for the treatment of recurrent high-grade glioma.

PURPOSE: To assess the efficacy and toxicity of KRN8602 when administered as an intravenous bolus to patients with recurrent high-grade malignant glioma. PATIENTS AND METHODS: Patients with recurrent or persistent anaplastic astrocytoma or glioblastoma multiforme who had not received recent chemotherapy or radiotherapy and were of good performance status (Eastern Cooperative Oncology Group score < or = 2) were treated with an intravenous bolus of 40 mg/m(2) KRN8602 every 28 days. Tumor responses were assessed radiologically and clinically after every second cycle of therapy. Treatment was continued until documented progression or a total of six cycles. RESULTS: A median of three cycles (range, one to six cycles) of KRN8602 was administered to 55 patients, 49 of whom received at least two cycles and were, therefore, assessable for response. The overall response rate (disease stabilization or better) was 43% (95% confidence interval, 29% to 58%). There were three complete responses, one partial response, seven minor responses, and 10 patients with stable disease. The median time to progression was 2 months (range, 1.5 to 37 months) and overall survival was 11 months (range, 1.5 to 40 months). Neutropenia was the most common toxicity, although it was generally of brief duration, and there were only seven episodes of febrile neutropenia in 176 cycles delivered. Nonhematologic toxicity was mostly gastrointestinal (nausea and vomiting, diarrhea) and events were grade 2 or lower except for a single episode of grade 3 vomiting. CONCLUSION: KRN8602 is an active new agent with minimal toxicity in the treatment of relapsed or refractory high-grade glioma. Further studies with KRN8602 in combination with other cytotoxics and in adjuvant treatment of gliomas are warranted.

A prospective randomized trial of KRN8602 and cytosine arabinoside vs. daunorubicin and cytosine arabinoside in adult patients with newly diagnosed acute myelogenous leukemia. The KRN8602 Leukemia Study Group.

A prospective randomized study was conducted to compare the efficacy and toxicity of two anthracyclines for the treatment of patients with acute myelogenous leukemia (AML). Fifty-eight patients were randomized and received induction therapy consisting of cytosine arabinoside (AraC) 100 mg/m2/day for 7 days combined with either KRN8602 (3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin hydrochloride [KRN]) 15 mg/m2/day for 5 days (KRN/AraC group) or daunorubicin (DNR) 40 mg/m2/day for 3 days (DNR/AraC group). Complete remission rate was 78.6% (22/28) in the KRN/AraC group and 73.1% (19/26) in the DNR/AraC group. There was a higher incidence of nausea/vomiting and anorexia observed in the KRN/AraC group compared to the DNR/AraC group, while the incidence of other adverse effects (stomatitis, diarrhea, and infectious complications) were similar between both groups. No electrocardiogram (ECG) abnormalities were observed after treatment in the KRN/AraC group, while in the DNR/AraC group, one patient showed ECG abnormality and three patients exhibited either arrhythmia, heart failure, or tachycardia. Mental disorder was reported in two cases in the KRN/AraC group. These findings suggest that KRN/AraC is similar in effectiveness to DNA/AraC but more toxic in central nervous system and gastrointestinal symptoms and less toxic regarding cardiac function in patients with previously untreated AML.

[Combination effect of hyperthermia and MX2 on cultured glioma cell lines].

MX2, a new lipophilic morpholino anthracycline, has been reported to have chemotherapeutic effects superior to those of adriamycin against murine and human glioma cells in vitro and in vivo. To assess the combination effect of MX2 and hyperthermia in vitro, the thermo-chemosensitivities of cultured human (U251MG and KC) and rat (C6 and 9L) glioma cell lines were examined by 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. The number of viable cells in each cell line was markedly and dose-dependently decreased by MX2 treatment, but the sensitivity of U251MG to MX2 was less than that of the other cell lines. The survival of each cell line was decreased with the hyperthermic treatment at 43 degrees C for 60 minutes. Combined treatment with MX2 and hyperthermia had an additive effect on cultured glioma cells when MX2 was added to the medium at a dose below 50 ng/ml. However, combined treatment indicated neither an additive nor a synergistic effect when the dose of MX2 was above 50 ng/ml. We conclude that MX2 may be clinically useful against malignant gliomas when administered alone or in combination with hyperthermia.

A phase II study of KRN8602(MX2), a novel morpholino anthracycline derivative, in patients with recurrent malignant glioma.

KRN8602(MX2) is a newly developed morpholino-anthracycline that has been found to cross the blood-brain barrier and be distributed in brain tissue after intravenous administration and to be effective against human glioma cells and the intracerebrally transplanted tumors in vivo. In order to confirm these promising preclinical observations clinically, we performed a phase II trial of KRN8602 in patients with recurrent malignant glioma. The 44 patients enrolled received at least 2 cycles of KRN8602 35 mg/m2/day at 3-4 week intervals by intravenous bolus. Of the 44 patients, 37 could be evaluated for response, and 39 for toxicity. One patient with anaplastic astrocytoma had a complete response (1/37, 3%), and 2 patients with anaplastic astrocytoma and 1 with brain stem glioma had a partial response (3/37, 8%). The overall response rate was 11% (4/37). All patients who responded had received prior chemotherapy that included nitrosoureas. No response was observed in the patients with glioblastoma. Myelosuppression was moderately severe, with 72% of patients developing grade 3 or 4 leukopenia. Severe nausea/vomiting was observed in 31% of the patients. No severe cardiotoxicity was observed. The results indicate that KRN8602 has modest activity against recurrent malignant glioma with relatively severe, but manageable toxicity. It seems to be worthwhile to further assess the efficacy and toxicity of KRN8602 against malignant glioma, which is generally less sensitive to chemotherapy.

A phase II study employing combination regimens containing KRN8602 in drug-resistant acute myeloid leukemia and acute lymphoblastic leukemia. KRN8602 Leukemia Study Group.

We conducted a phase II multicenter study in order to evaluate the efficacy and toxicity of two combination regimens containing KRN8602 (MX2) for drug-resistant acute myeloid leukemia (AML) and acute lymphoblastic leukemia (ALL). AML was treated with KRN8602, 15 mg/m2 i.v. push for 5 days, and cytarabine (AraC), 100 mg/m2 by 24 h coutinuous infusion for 7 days. ALL was treated with KRN8602, 15 mg/m2 i.v. push for 5 days, vincristine (VCR), 1.4 mg/m2 i.v. push, once weekly, and prednisolone (PSL), 40 mg/m2, 3 h infusion for 5 days. In AML and ALL, the complete remission (CR) rate was 36.4% (16 of 44) and 24.1% (seven of 29), and the overall response rate (CR+PR) was 52.3% (23 of 44) and 51.7% (15 of 29), respectively. Among the 29 relapsed cases of AML, a higher CR rate, 51.7% (15 of 29), was obtained. A high incidence of nausea/vomiting and anorexia was observed, and some patients experienced central nervous system disorders and peripheral neuropathy. There was a low incidence of severe neurotoxicities; all other toxicities were manageable. KRN8602 was found to overcome drug resistance clinically, confirming results based on the preclinical studies. We conclude that KRN8602 is an effective novel anthracycline for drug-resistant acute leukemias.

Phase II study of KRN8602, 3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin hydrochloride, MX2 x HCl in patients with metastatic breast cancer.

PURPOSE: KRN8602 (3'-deamino-3'-morpholino-13-deoxo-10-hydroxycarminomycin hydrochloride, MX2 x HCl) is a newly developed anthracycline that has been found to be effective against multidrug-resistant tumor cells in vitro and in vivo. In order to clinically confirm these promising preclinical observations, we performed a phase II trial of KRN8602 in patients with anthracycline-resistant metastatic breast cancer. METHODS: Of 41 patients registered with metastatic breast cancer, 37 were eligible and were given at least two cycles of KRN8602 15 mg/m2 per day at 3-4 week intervals by intravenous bolus injection on days 1, 2, and 3. RESULTS: Of the 37 patients, 6 (16.2%, with a 95% confidence interval of 4.3-28.1%) had a partial response (PR). No complete responses (CRs) were observed. The difference between response rates according to prior history of anthracycline administration was not significant. Myelosuppression was moderately severe, with grade 3 or 4 leukopenia occurring in 65%. Severe nausea/vomiting was observed in 44% of the patients. CONCLUSIONS: The results indicate that KRN8602 has modest activity in refractory metastatic breast cancer and is associated with relatively severe toxicity. Furthermore, the preclinical finding that KRN8602 overcomes anthracycline resistance was not reliably reproduced in this clinical phase II trial.

Induction of MDR1 gene expression by anthracycline analogues in a human drug resistant leukaemia cell line.

The effects of 4-demethoxydaunorubicin (idarubicin, IDA) and MX2, a new morpholino-anthracycline, on up-regulation of the MDR1 gene in the low-level multidrug resistant (MDR) cell line CEM/A7R were compared at similar concentrations (IC10, IC50 and IC90) over a short time exposure (4 and 24 h). The chemosensitivity of each drug was determined by a 3-day cell growth inhibition assay. Compared with epirubicin (EPI), IDA and MX2 were 17- and eightfold more effective in the CEM/A7R line respectively. No cross-resistance to 5-FU was seen in the CEM/A7R line. Verapamil (5 microM) and PSC 833 (1 microM), which dramatically reversed resistance to EPI in the CEM/A7R line, had no sensitizing effect on the resistance of this line to MX2, but slightly decreased resistance to IDA. The sensitivity to 5-FU was unchanged by these modulators. The induction of MDR1 mRNA expression by IDA, MX2 and 5-FU was analysed by Northern blotting and semiquantitatively assessed by scanning Northern blots on a phosphorimager. The relative level of MDR1 expression was expressed as a ratio of MDR1 mRNA to the internal RNA control glyceraldehyde-3-phosphate dehydrogenase (GAPDH). IDA, MX2 and 5-FU differentially up-regulated MDR1 mRNA in the CEM/A7R line in a dose-dependent manner. Both IDA and MX2 induced MDR1 expression within 4 h. 5-FU up-regulated MDR1 expression only when drug exposure was prolonged to 24 h. Based on MRK 16 binding, flow cytometric analysis of P-glycoprotein (Pgp) expression paralleled the increase in MDR1 mRNA levels. For the three anthracyclines, the increase in MDR1 expression was stable in cells grown in the absence of drug for more than 3 weeks after drug treatment. The induction of MDR1 expression by 5-FU was transient, associated with a rapid decrease in the increased Pgp levels which returned to baseline 72 h after the removal of 5-FU. This study demonstrates that MDR1 expression can be induced by analogues of anthracyclines not pumped by Pgp, and that this induction appears to be stable despite a 3-week drug-free period.

[Pilot late phase II study of KRN8602 (MX2), a novel anthracycline derivative, for acute leukemia--a dose finding study in combination].

In order to determine the clinically optimal dose of KRN8602, a new anthracycline derivative, in combination therapy for acute leukemia, we performed a pilot late phase II study in combination with cytarabine (Ara-C) for acute myelogenous leukemia (AML), and with vincristine (VCR) and prednisolone (PSL) for acute lymphocytic leukemia (ALL). KRN8602 was given at a dose of 12 or 15 mg/m2 for 5 consecutive days, Ara-C at a dose of 100 mg/m2 for 7 consecutive days, VCR 1.4 mg/m2 (max. 2.0 mg/body) weekly for 4 weeks, and PSL 40 mg/m2 for principally 28 consecutive days. Of 14 patients with relapsed or refractory leukemia entered in the study, thirteen patients were evaluable for safety and 12 were evaluable for response. In AML, there was 1 partial response (PR) in 4 patients at a dose of 12 mg/m2. Against 1 complete response (CR) and 3 PRs in 4 patients at a dose of 15 mg/m2. In ALL, there was 1 PR in 1 case at a dose of 12 mg/m2, and 1 CR and 2 PR in 3 at a dose of 15 mg/m2. Major toxicities were nausea/vomiting and anorexia, but incidences and grades of toxicities were not dose-dependent, and all toxicities were tolerable and manageable. From these results it is concluded that the optimal dose of KRN8602 is 15 mg/m2 for 5 consecutive days in combination with Ara-C for AML, and with VCR and PSL for ALL.

Synthesis of phosphoramide mustard analogues of daunomycin and carminomycin.

New phosphoramide mustards (6-8) have been prepared from the antibiotics 2 and 3, and from 5. The mixture of cyclophosphamides could be separated by preparative layer and column chromatography. The assignments of configuration to the isomeric phosphoramidates was based on the magnetic anisotropy of the P = O bond. The synthesized compounds 6a,b-8a,b (mixture of isomers) were tested for inhibitory activity on the [3H]-thymidine incorporation into the DNA of tumor cells, using ovarian carcinoma cell line.