A phase I trial of weekly paclitaxel, 13- cis-retinoic acid, and interferon alpha in patients with prostate cancer and other advanced malignancies.

PURPOSE: Based on prior studies demonstrating the effect of 13- cis-retinoic acid and interferon alpha (CRA/IFN) in decreasing the expression of the antiapoptotic protein bcl-2, our prior clinical study of CRA/IFN with paclitaxel (TAX) administered every 3 weeks, and data demonstrating increased activity of weekly TAX against prostate cancer, we designed a phase I study of weekly TAX in combination with CRA/IFN in patients with prostate cancer and other advanced malignancies. To develop a marker of drug effect, we assessed bcl-2 downregulation in patient peripheral blood mononuclear cells (PBMC). METHODS: Enrolled in the study were 14 patients with prostate cancer or other advanced malignancies, and 13 were treated with 1 mg/kg CRA on days 1 and 2, 6 MU/m(2) IFN subcutaneously on days 1 and 2, and TAX at increasing doses on day 2 each week for 6 weeks out of an 8-week cycle. The effect of CRA/IFN on bcl-2 expression was assessed in PBMCs by immunoblotting. RESULTS: The combination of CRA/IFN and TAX was well tolerated. Dose-limiting toxicities (DLT) in the first cycle of therapy included one patient with fever and neutropenia, and one patient with grade 4 hypertriglyceridemia. The recommended phase II dose of TAX in this combination was 80 mg/m(2). Of 13 patients assessable by tumor markers or scans, 5 had stable disease and 2 had a biochemical partial response including a patient with a decrease in PSA of >50% while on study. The assessment of patient PBMC bcl-2 was feasible in ten patients. CONCLUSIONS: This is the first study in which the safety and clinical activity of weekly TAX combined with CRA/IFN has been demonstrated. The assessment of PBMC bcl-2 is feasible in this weekly chemotherapy schedule

Mitoxantrone in patients with prostate specific antigen progression after local therapy for prostate carcinoma.

BACKGROUND: Molecular mechanisms of chemotherapy resistance are present in prostate carcinoma, some of which increase after androgen ablation (AA) therapy. Therefore, the authors hypothesized that chemotherapy in patients with prostate specific antigen (PSA) progression after local therapy, before androgen ablation therapy, will have greater antitumor activity. METHODS: Twenty-three hormone-naive patients with PSA progression after prostatectomy or radiation therapy were registered in this study. Twenty-two were treated with 10 mg/m(2) of mitoxantrone initially, followed by 12 mg/m(2) every 3 weeks for a maximum of 8 cycles. Prostatectomy specimens were assessed, when possible, for topoisomerase II alpha, multidrug resistance protein MRP, and bcl-2 by immunohistochemistry. RESULTS: Twenty-two patients received a total of 131 cycles of therapy. Three patients had transient Grade 3 or 4 neutropenia without fever. During treatment, 10 of 22 patients showed a decrease in PSA, without an associated decrease in testosterone. In this group of 10 patients, the mean PSA decrease was 29% at 3 months and 43% at 6 months. Overall, 4 of 22 patients had a decrease in PSA of greater than or equal to 50%. The PSA decreased in three of seven patients whose cancer overexpressed MRP and in three of seven patients who overexpressed bcl-2. No patient with overexpression of topoisomerase II alpha (n = 4) had a decrease in PSA during the study. CONCLUSIONS: To the authors' knowledge, this is the first reported study of mitoxantrone in patients with hormone-naive prostate carcinoma and PSA progression after local therapy; mitoxantrone was safe and biochemically active, similar to prior studies in hormone refractory prostate carcinoma, suggesting that critical molecular mechanisms of chemotherapy resistance are present independent of AA. Further studies are warranted to determine whether pharmacogenomic assessment of topoisomerase II, MRP, or bcl-2 may predict for response to mitoxantrone.