an-207 and Prostatic-Neoplasms

Targeted chemotherapy is a modern approach aimed at increasing the efficacy of systemic chemotherapy and reducing its side effects. The peptide receptors expressed primarily on cancerous cells can serve as targets for a selective destruction of malignant tumors. Binding sites for LHRH (now known in genome and microarray databases as GNRH1), were found on 52% of human breast cancers, about 80% of human ovarian and endometrial cancers, and 86% of human prostatic carcinoma specimens. Because LHRH receptors are not expressed on most normal tissues, they represent a specific target for cancer chemotherapy with antineoplastic agents linked to an LHRH vector molecule. To test the efficacy of targeted chemotherapy based on LHRH analogs, we recently developed a cytotoxic analog of LHRH, designated AN-152, which consists of [D-Lys6]LHRH covalently linked to one of the most widely used chemotherapeutic agents, doxorubicin (DOX). In addition, we designed and synthesized a highly active derivative of DOX, 2-pyrrolino-DOX (AN-201), which is 500-1000 times more potent than DOX in vitro. AN-201 is active against tumors resistant to DOX, and noncardiotoxic. As in the case of DOX, AN-201 was coupled to carrier peptide [D-Lys6]LHRH to form a superactive targeted cytotoxic LHRH analog, AN-207. Both AN-152 and AN-207 can effectively inhibit the growth of LHRH receptor-positive human breast, ovarian, endometrial, and prostate cancers xenografted into nude mice. DOX-containing cytotoxic LHRH analog AN-152 is scheduled for clinical phase I/IIa trials in patients with advanced ovarian and breast cancers in 2005.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Doxorubicin; Endometrial Neoplasms; Epithelial Cells; Female; Gonadotropin-Releasing Hormone; Humans; Male; Ovarian Neoplasms; Prostatic Neoplasms; Pyrroles; Receptors, LHRH

Receptors for luteinizing hormone-releasing hormone (LHRH) on human prostate cancers can be used for targeted chemotherapy with cytotoxic analogs of LHRH, such as AN-207, which consists of superactive doxorubicin derivative 2-pyrrolino doxorubicin (AN-201) linked to carrier [D-Lys6] LHRH.. The effects of AN-207 and AN-201 were investigated in DU-145 androgen independent and LuCaP-35 androgen sensitive human prostate cancers xenografted into nude mice. Toxicity was evaluated by survival rates, changes in body weights, and leukocyte counts. LHRH receptors on DU-145 and LuCaP-35 tumors were evaluated by radioreceptor assays and RT-PCR. The effects on apoptosis and cell proliferation were investigated by histology and evaluation of apoptotic oncogenes Bcl-2 and Bax by Western Blot analysis.. AN-207 inhibited growth of DU-145 tumors significantly by 75% (P < 0.01) and LuCaP-35 human prostate cancers by 80% (P < 0.01), and was less toxic than AN-201. Receptors for LHRH were expressed on DU-145 and LuCaP-35 tumors. Blockade of LHRH receptors with LHRH agonist Triptorelin nullified the effects of AN-207. Treatment with AN-207, but not with AN-201, decreased Bcl-2/Bax ratio in DU-145 tumors and Bcl-2 in LuCaP-35 tumors indicating an increase in apoptotic activity. AN-207, but not AN-201, decreased cell proliferation in both models.. Targeted chemotherapy with AN-207 could be considered for treatment of advanced prostate cancer.

Topics: Androgens; Animals; Antineoplastic Agents; Apoptosis; bcl-2-Associated X Protein; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Disease Progression; Doxorubicin; Gonadotropin-Releasing Hormone; Humans; Male; Mice; Mice, Nude; Neoplasm Transplantation; Prostatic Neoplasms; Proto-Oncogene Proteins c-bcl-2; Pyrroles; Receptors, LHRH; RNA, Messenger; Transplantation, Heterologous; Triptorelin Pamoate

The efficacy of therapy with targeted cytotoxic luteinizing hormone-releasing hormone (LHRH) analog AN-207 consisting of superactive doxorubicin derivative AN-201 linked to carrier [D-Lys(6)]LH-RH was evaluated in vivo in nude mice bearing xenografts of MDA-PCa-2b prostate cancer line. AN-207 was administered intravenously (i.v.) at 200 nmol/kg on day 1 and at 150 nmol/kg on day 14. After 4 weeks of treatment with AN-207, tumor growth was inhibited as shown by a 63% (P<0.01) decrease in tumor volume and a 55% (P<0.05) reduction in tumor weight, compared with controls. None of the animals died after administration of AN-207 at the total dose of 350 nmol/kg, and at the end of the experiment the body weights of mice given AN-207 did not differ significantly from controls. A single injection of cytotoxic radical AN-201 at 200 nmol/kg resulted in 43% mortality. In the surviving mice, AN-201 caused a 50% inhibition in tumor volume and a 27% reduction in tumor weight, which were non-significant, as compared to the controls. After 4 weeks, serum prostate-specific antigen concentrations in mice treated with AN-207 were 65% lower than those in controls (P<0.05), while in animals given AN-201 the reduction in serum prostate-specific antigen was only 40% (NS). The expression of mRNA for LHRH receptors was detected by reverse transcriptase polymerase chain reaction (RT-PCR) in MDA-PCa-2b tumors. The present study indicates that chemotherapy targeted to LHRH receptors on tumors inhibits growth of MDA-PCa-2B prostate cancers representative of human carcinoma disseminated to the bone and progressing despite androgen withdrawal.

Topics: Animals; Antineoplastic Agents; Cell Division; Dose-Response Relationship, Drug; Doxorubicin; Gonadotropin-Releasing Hormone; Humans; Luteinizing Hormone; Male; Mice; Mice, Nude; Prostatic Neoplasms; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Time Factors; Tumor Cells, Cultured

Receptors for luteinizing hormone-releasing hormone (LH-RH) found in prostate cancers might be used for targeting of chemotherapeutic agents. Doxorubicin derivative 2-pyrrolinodoxorubicin (AN-201) can be linked to carrier analog [D-Lys6]LH-RH to form the targeted cytotoxic analog of LH-RH, AN-207.. We evaluated the effects of AN-207 and its components on the growth of LH-RH receptor-positive human prostate cancer PC-82 xenografted into nude mice. Analog AN-207, radical AN-201, carrier [D-Lys6]LH-RH, or a mixture of [D-Lys6]LH-RH and AN-201 were injected intravenously once at doses of 200 nmol/kg. Tumor growth, body weight, total WBC counts, and serum prostate-specific antigen (PSA) were determined. Receptors for LH-RH on PC-82 tumors were evaluated, and the expression of mRNA for LH-RH receptors was assessed by RT-PCR.. Eight weeks after administration of cytotoxic analog AN-207, there was a 67.8% reduction in tumor volume (P < 0.01), 70.7% decrease in tumor burden (P < 0.01), and 36.5% decrease in serum PSA levels (P < 0.01) as compared with controls. Only one of 8 animals treated with AN-207 died. Cytotoxic radical AN-201 caused a 34.2% (not significant, NS) reduction in tumor volume with no change in serum PSA, and killed 3 of 8 mice due to toxicity. Carrier [D-Lys6]LH-RH and the unconjugated mixture of [D-Lys6]LH-RH and AN-201 had no effect on tumor growth. LH-RH receptors as well as the expression of their mRNA were found in PC-82 tumors.

Topics: Adenocarcinoma; Animals; Antineoplastic Agents; Doxorubicin; Drug Delivery Systems; Gonadotropin-Releasing Hormone; Humans; Male; Mice; Mice, Nude; Models, Chemical; Polymerase Chain Reaction; Prostatic Neoplasms; Pyrroles; Receptors, LHRH; Transplantation, Heterologous; Tumor Cells, Cultured