A phase I and pharmacokinetic study of the oral histone deacetylase inhibitor, MS-275, in patients with refractory solid tumors and lymphomas.

PURPOSE: To evaluate the toxicity profile, pharmacologic, and biological properties of 3-pyridylmethyl N-{4-[(2-aminophenyl)carbamoyl]benzyl}carbamate (MS-275), a histone deacetylase inhibitor, when administered orally on three different dosing schedules. EXPERIMENTAL DESIGN: Patients with advanced solid malignancies and lymphomas were treated on three dose schedules: once every other week, twice weekly for 3 weeks every 28 days, and once weekly for 3 weeks every 28 days. First-cycle plasma pharmacokinetics and peripheral blood mononuclear cell histone acetylation were determined. RESULTS: Twenty-seven patients received > or =149 courses of treatment. Hypophosphatemia and asthenia were dose limiting on the weekly and twice-weekly dosing schedules; there was no dose-limiting toxicity on the every other week schedule. Pharmacokinetic variables revealed dose-dependent and dose-proportional increases. Two of 27 patients showed partial remissions, including one patient with metastatic melanoma who had a partial response and has remained on study for >5 years. Six patients showed prolonged disease stabilization. Levels of histone H3 and H4 acetylation in peripheral blood mononuclear cells increased qualitatively but with a high degree of interpatient variation. CONCLUSIONS: MS-275 is well tolerated at doses up to 6 mg/m(2) every other week or 4 mg/m(2) weekly for 3 weeks followed by 1 week of rest and results in biologically relevant plasma concentrations and antitumor activity. Twice-weekly dosing was not tolerable due to asthenia, and further evaluation of this schedule was halted. The recommended dose for further disease-focused studies is 4 mg/m(2) given weekly for 3 weeks every 28 days or 2 to 6 mg/m(2) given once every other week.

Multicenter phase II trial of the histone deacetylase inhibitor pyridylmethyl-N-{4-[(2-aminophenyl)-carbamoyl]-benzyl}-carbamate in pretreated metastatic melanoma.

Systemic treatment of metastatic melanoma is of low efficacy, and new therapeutic strategies are needed. Histone deacetylase inhibitors are supposed to restore the expression of tumor suppressor genes and induce tumor cell differentiation, growth arrest, and apoptosis. This study was aimed to evaluate the efficacy, safety, and pharmacokinetics of the histone deacetylase inhibitor pyridylmethyl-N-{4-[(2-aminophenyl)-carbamoyl]-benzyl}-carbamate (MS-275) in patients with pretreated metastatic melanoma. Patients with unresectable AJCC stage IV melanoma refractory to at least one earlier systemic therapy were randomized to receive MS-275 3 mg biweekly (days 1+15, arm A) or 7 mg weekly (days 1+8+15, arm B), in 4-week cycles. The primary study endpoint was objective tumor response, secondary endpoints were safety and time-to-progression. On the basis of Simon's two-stage design, the study initially allowed an entry of 14 patients per arm; if there was at least one responder, additional 33 patients were to be enrolled. Among 28 patients enrolled, no objective response was detected. Four (29%) patients in arm A and three (21%) patients in arm B showed disease stabilizations. Median time-to-progression was comparable in both arms with 55.5 versus 51.5 days, respectively; median overall survival was 8.84 months. Toxicity was mild to moderate with nausea (39%) and hypophosphatemia (29%) as the most frequently reported events. No treatment-related serious adverse events occurred. Single-agent treatment with MS-275 was well-tolerated and showed long-term tumor stabilizations, but no objective responses in pretreated metastatic melanoma. Further evaluation of MS-275 in combination schedules is warranted.

Phase III intergroup study of fludarabine phosphate compared with cyclophosphamide, vincristine, and prednisone chemotherapy in newly diagnosed patients with stage III and IV low-grade malignant Non-Hodgkin's lymphoma.

PURPOSE: To compare the efficacy and safety of fludarabine phosphate with cyclophosphamide, vincristine, and prednisone (CVP) in 381 previously untreated, advanced-stage, low-grade (lg) non-Hodgkin's lymphoma (NHL) patients in a phase III, multicenter study. PATIENTS AND METHODS: Between 1993 and 1997, patients were randomly assigned to treatment with either fludarabine (25 mg/m2 intravenously [IV] daily for 5 days every 4 weeks) or CVP (cyclophosphamide 750 mg/m2 IV on day 1; vincristine, 1.4 mg/m2 IV on day 1; and prednisone, 40 mg/m2 orally on days 1 through 5 every 4 weeks). Results Overall response (OR) rates were significantly improved in the fludarabine arm versus the CVP arm, both for the intent-to-treat (ITT) population and assessable patients (P < .001). Complete response (CR) rates in the ITT population were also higher after fludarabine treatment. The CR rate was 38.6% for fludarabine compared with 15.0% for CVP. There were no statistically significant differences in time to progression (TTP), time to treatment failure (TTF), and overall survival (OS) between treatment groups. WHO grades 3 and 4 hematologic adverse events were more common in the fludarabine arm. However, concerning the higher incidence of granulocytopenia, this did not translate to more infections in fludarabine-treated patients. CONCLUSION: Newly diagnosed lgNHL patients who received fludarabine achieved higher OR and CR rates compared with CVP-treated patients. No differences in TTP, TTF, and OS were noted. Fludarabine is a highly active single agent in lgNHL. Combination therapies incorporating fludarabine are now being further evaluated as first-line therapy in follicular NHL.

Characterization of novel monoclonal antibodies for prostate-specific antigen (PSA) with potency to recognize PSA bound to alpha 2-macroglobulin.

BACKGROUND: Different molecular forms of prostate-specific antigen (PSA) have been used to differentiate between benign prostatic hyperplasia and prostate cancer. Detecting PSA bound to endogenous inhibitors such as alpha(1)-antichymotrypsin (ACT) and alpha(2)-macroglobulin (alpha(2)M) is often difficult because of epitope masking or sensitivity problems. Here we report the characterization of four novel mouse monoclonal antibodies (mabs) obtained by immunization with PSA-alpha(2)M complexes. Their ability to detect free PSA and PSA-inhibitor complexes was shown, and their epitopes were analyzed by phage display technology. METHODS: The properties of the mabs were studied by competition and sandwich assays and by Western blotting. Epitope mapping was performed by screening of a phage display peptide library. RESULTS: All four mabs recognized free PSA, PSA-ACT, and PSA-alpha(2)M complexes, but to various degrees. With different combinations of mabs in competition experiments, antibodies were identified that enhance binding of other mabs to PSA, forming the molecular basis of a very sensitive assay for the detection of PSA and PSA-ACT complexes. Mabs with highest reactivity for PSA-alpha(2)M were selected to establish an immunoassay for that complex. Western blot analysis revealed that all mabs recognized conformational epitopes of PSA. These findings were supported by phage display results demonstrating mimotopes in the PSA molecule. CONCLUSION: The results presented here could aid in the further development of clinically relevant assays for PSA and PSA-alpha(2)M complexes.