Leonel Ochoa

Phase I and Pharmacokinetic Study of XRP6258 (RPR 116258A), a Novel Taxane, Administered as a 1-Hour Infusion Every 3 Weeks in Patients with Advanced Solid Tumors

Purpose: To assess the feasibility of administering XRP6258, a new taxane with a low affinity for the multidrug resistance 1 protein, as a 1-hour i.v. infusion every 3 weeks. The study also sought to determine the maximum tolerated dose and the recommended dose, to describe the pharmacokinetic (PK) behavior of the compound, and to seek preliminary evidence of anticancer activity. Experimental Design: Twenty-five patients with advanced solid malignancies were treated with 102 courses of XRP6258 at four dose levels ranging from 10 to 25 mg/m2. Dose escalation was based on the occurrence of dose-limiting toxicity (DLT) at each dose level, provided that PK variables were favorable. The maximum tolerated dose was defined as the dose at which at least two patients developed a DLT at the first course. Results: Neutropenia was the principal DLT, with one patient experiencing febrile neutropenia and two others showing prolonged grade 4 neutropenia at the 25 mg/m2 dose level. Nonhematologic toxicities, including nausea, vomiting, diarrhea, neurotoxicity, and fatigue, were generally mild to moderate in severity. XRP6258 exhibited dose-proportional PK, a triphasic elimination profile, a long terminal half-life (77.3 hours), a high clearance (mean CL, 53.5 L/h), and a large volume of distribution (mean Vss, 2,034 L/m2). Objective antitumor activity included partial responses in two patients with metastatic prostate carcinoma, one unconfirmed partial response, and two minor responses. Conclusion: The recommended phase II dose of XRP6258 on this schedule is 20 mg/m2. The general tolerability and encouraging antitumor activity in taxane-refractory patients warrant further evaluations of XRP6258.

Cantuzumab Mertansine, a Maytansinoid Immunoconjugate Directed to the CanAg Antigen: A Phase I, Pharmacokinetic, and Biologic Correlative Study

PURPOSE To determine the maximum tolerated dose and pharmacokinetics of cantuzumab mertansine, an immunoconjugate of the potent maytansine derivative (DM1) and the humanized monoclonal antibody (huC242) directed to CanAg, intravenously (i.v.) once every 3 weeks and to seek evidence of antitumor activity. PATIENTS AND METHODS Patients with CanAg-expressing solid malignancies were treated with escalating doses of cantuzumab mertansine administered i.v. every 3 weeks. The pharmacokinetic parameters of cantuzumab mertansine, the presence of plasma-shed CanAg, and the development of both human antihuman and human anti-DM1 conjugate antibodies also were characterized. RESULTS Thirty-seven patients received 110 courses of cantuzumab mertansine at doses ranging from 22 to 295 mg/m2. Acute, transient, and reversible elevations of hepatic transaminases were the principal toxic effects. Nausea, vomiting, fatigue, and diarrhea were common but rarely severe at the highest dose levels. Dose, peak concentration, and area under the concentration-time curve correlated with the severity of transaminase elevation. The mean (+/- SD) clearance and terminal elimination half-life values for cantuzumab mertansine averaged 39.5 (+/-13.1) mL/h/m2 and 41.1 (+/-16.1) hours, respectively. Strong expression (3+) of CanAg was documented in 68% of patients. Two patients with chemotherapy-refractory colorectal carcinoma had minor regressions, and four patients had persistently stable disease for more than six courses. CONCLUSION The recommended dose for cantuzumab mertansine is 235 mg/m2 i.v. every 3 weeks. The absence of severe hematologic toxic effects, preliminary evidence of cantuzumab mertansine tumor localization, and encouraging biologic activity in chemotherapy-refractory patients warrant further broad clinical development of this immunoconjugate in CanAg-expressing tumors.

A Phase I and Pharmacokinetic Study of Pegylated Camptothecin as a 1-Hour Infusion Every 3 Weeks in Patients With Advanced Solid Malignancies

PURPOSE To assess the feasibility of administering camptothecin (CPT), the prototypic topoisomerase I inhibitor, as polyethylene glycol (PEG)-CPT, a macromolecule consisting of CPT conjugated to chemically modified PEG. The study also sought to determine the maximum-tolerated dose (MTD) of PEG-CPT, characterize its pharmacokinetic behavior, and seek preliminary evidence of anticancer activity. PATIENTS AND METHODS Patients with advanced solid malignancies were treated with escalating doses of PEG-CPT as a 1-hour intravenous (IV) infusion every 3 weeks. A modified continual reassessment method was used for dose-level assignment to determine the MTD, which was defined as the highest dose level at which the incidence of dose-limiting toxicity did not exceed 20%. RESULTS Thirty-seven patients were treated with 144 courses of PEG-CPT at seven dose levels ranging from 600 to 8,750 mg/m(2). Severe myelosuppression was consistently experienced by heavily pretreated (HP) and minimally pretreated (MP) patients at the highest dose level evaluated, 8,750 mg/m(2), whereas both HP and MP patients tolerated repetitive treatment at 7,000 mg/m(2). Cystitis, nausea, vomiting, and diarrhea were also observed but were rarely severe. A partial response was noted in a patient with platinum- and etoposide-resistant small-cell lung carcinoma, and minor responses were noted in one patient each with adenocarcinoma of unknown primary type and osteosarcoma. The pharmacokinetics of free CPT were dose proportional. Free CPT accumulated slowly in plasma, with maximal plasma concentrations achieved at 23 +/- 12.3 hours; the harmonic mean half-life (t(1/2)) of free CPT was long (t(1/2), 77.46 +/- 36.77 hours). CONCLUSION Clinically relevant doses of CPT can be delivered by administering PEG-CPT. The recommended dose for phase II studies in both MP and HP patients is 7,000 mg/m(2) as 1-hour IV every 3 weeks. The characteristics of the myelosuppressive effects of PEG-CPT, the paucity of severe nonhematologic toxicities with repetitive treatment, the preliminary antitumor activity noted, and the slow clearance of CPT enabling simulation of desirable pharmacokinetic parameters with a convenient single-dosing regimen warrant further disease-directed evaluations.

Phase 1-2a multicenter dose-escalation study of ezatiostat hydrochloride liposomes for injection (Telintra®, TLK199), a novel glutathione analog prodrug in patients with myelodysplastic syndrome

BackgroundEzatiostat hydrochloride liposomes for injection, a glutathione S-transferase P1-1 inhibitor, was evaluated in myelodysplastic syndrome (MDS). The objectives were to determine the safety, pharmacokinetics, and hematologic improvement (HI) rate. Phase 1-2a testing of ezatiostat for the treatment of MDS was conducted in a multidose-escalation, multicenter study. Phase 1 patients received ezatiostat at 5 dose levels (50, 100, 200, 400 and 600 mg/m2) intravenously (IV) on days 1 to 5 of a 14-day cycle until MDS progression or unacceptable toxicity. In phase 2, ezatiostat was administered on 2 dose schedules: 600 mg/m2 IV on days 1 to 5 or days 1 to 3 of a 21-day treatment cycle.Results54 patients with histologically confirmed MDS were enrolled. The most common adverse events were grade 1 or 2, respectively, chills (11%, 9%), back pain (15%, 2%), flushing (19%, 0%), nausea (15%, 0%), bone pain (6%, 6%), fatigue (0%, 13%), extremity pain (7%, 4%), dyspnea (9%, 4%), and diarrhea (7%, 4%) related to acute infusional hypersensitivity reactions. The concentration of the primary active metabolites increased proportionate to ezatiostat dosage. Trilineage responses were observed in 4 of 16 patients (25%) with trilineage cytopenia. Hematologic Improvement-Erythroid (HI-E) was observed in 9 of 38 patients (24%), HI-Neutrophil in 11 of 26 patients (42%) and HI-Platelet in 12 of 24 patients (50%). These responses were accompanied by improvement in clinical symptoms and reductions in transfusion requirements. Improvement in bone marrow maturation and cellularity was also observed.ConclusionPhase 2 studies of ezatiostat hydrochloride liposomes for injection in MDS are supported by the tolerability and HI responses observed. An oral formulation of ezatiostat hydrochloride tablets is also in phase 2 clinical development.Trial RegistrationClinicaltrials.gov: NCT00035867

Phase I and Pharmacokinetic Study of the Oral Fluoropyrimidine S-1 on a Once-Daily-for-28-Day Schedule in Patients with Advanced Malignancies

Purpose: The oral fluoropyrimidine S-1, which consists of a mixture of a 5-fluorouracil (5-FU) prodrug (tegafur), a dihydropyrimidine dehydrogenase inhibitor [5-chloro-2,4-dihydroxypyrimidine (CDHP)], and an inhibitor of orotate phosphoribosyltransferase [potassium oxonate (oxonic acid)], was developed to increase the feasibility and therapeutic index of 5-FU administered orally. The principal objective of this study was to assess the feasibility of administering S-1 on a once-daily-for-28-day schedule every 5 weeks, determine the maximum tolerated dose, characterize the pharmacokinetics of S-1, and seek evidence of anticancer activity. Experimental Design: Patients with advanced solid malignancies were treated with escalating doses of S-1 on a once-daily oral schedule for 28 days every 5 weeks. The maximum tolerated dose was defined as the highest dose in which fewer than two of the first six new patients experienced dose-limiting toxicity. The pharmacokinetic profiles of the tegafur, CDHP, and oxonic acid constituents were characterized. Results: Twenty patients were treated with 72 courses of S-1 at three dose levels ranging from 50 to 70 mg/m2/day. Diarrhea, which was often associated with abdominal discomfort and cramping, was the principal dose-limiting toxicity of S-1 on this protracted schedule. Nausea, vomiting, mucositis, fatigue, and cutaneous effects were also observed but were rarely severe. Myelosuppression was modest and uncommon. A partial response and a 49% reduction in tumor size were observed in patients with fluoropyrimidine- and irinotecan-resistant colorectal carcinoma. The pharmacokinetic data suggested potent inhibition of 5-FU clearance by CHDP, with resultant 5-FU exposure at least 10-fold higher than that reported from equitoxic doses of tegafur modulated by uracil in the oral fluoropyrimidine UFT. Conclusions: The recommended dose for Phase II studies of S-1 administered once daily for 28 consecutive days every 5 weeks is 50 mg/m2/day. The pharmacokinetic data indicate substantial modulation of 5-FU clearance by CDHP. Based on these pharmacokinetic data, the predictable toxicity profile of S-1, and the low incidence of severe adverse effects at the recommended Phase II dose, evaluations of S-1 on this schedule are warranted in malignancies that are sensitive to the fluoropyrimidines.