Objective: Most human endometrial and ovarian cancers express receptors for luteinizing hormone- releasing hormone. These receptors can be used for targeted chemotherapy with cytotoxic luteinizing hormone-releasing hormone analogs such as AN-152, in which doxorubicin is linked to [D-Lys(6)]luteinizing hormone-releasing hormone.
Study design: The antitumor effects of doxorubicin and AN-152 were assessed in vivo in human luteinizing hormone-releasing hormone receptor-positive HEC-1B endometrial cancers and NIH:OVCAR-3 ovarian cancers and in the luteinizing hormone-releasing hormone receptor-negative SK-OV-3 ovarian line. Nude mice bearing these tumors subcutaneously were injected intravenously with saline solution (control), AN-152, or doxorubicin at equimolar doses. Luteinizing hormone-releasing hormone receptor expression in tumors and specimens of human reproductive (n = 5) and nonreproductive (n = 15) normal tissues and in hematopoietic stem cells were analyzed with reverse transcriptase-polymerase chain reaction and radioligand binding assay.
Results: The tumor volumes of luteinizing hormone-releasing hormone receptor-positive HEC-1B and NIH:OVCAR-3 cancers were reduced significantly (P <.001) 1 week after treatment with AN-152 at 700 nmol/20 g or at 300 nmol/20 g. No toxic side effects were observed. Treatment with doxorubicin arrested tumor growth but did not reduce tumor volume. Doxorubicin at 700 nmol/20 g caused a high mortality rate and at 300 nmol/20 g (8.7 mg/kg) caused a loss of body weight, but no deaths occurred. The growth of luteinizing hormone-releasing hormone receptor-negative SK-OV-3 cancers was not affected by AN-152. Normal human nonreproductive tissues, hematopoietic stem cells, and vaginal tissue did not express luteinizing hormone-releasing hormone receptors, but luteinizing hormone-releasing hormone receptors were found in the ovary, fallopian tube, cervix, endometrium, and myometrium.
Conclusion: Targeted chemotherapeutic luteinizing hormone-releasing hormone analog AN-152 is more effective and less toxic than cytotoxic radical doxorubicin on luteinizing hormone-releasing hormone receptor-positive tumors. AN-152 could be considered for targeted chemotherapy in patients with ovarian or endometrial cancers.