Perifosine (NSC 639966) is a synthetic, substituted heterocyclic alkylphosphocholine that acts primarily at the cell membrane targeting signal transduction pathways. Early clinical trials were limited because of dose-limiting gastrointestinal toxicity, and parenteral dosing of this class of agents is not possible because of their hemolytic properties; therefore, related compounds with an improved therapeutic index were developed. Toxicity was minimized and efficacy improved by using a loading dose/maintenance dose schedule, and therefore, this schedule was carried into clinical trials. This phase I trial enrolled 42 patients with incurable solid malignancies. The starting doses were 100 mg p.o. ؋ four doses (every 6 hours) load followed by a 50 mg p.o. once daily maintenance dose with escalation of either component in successive dose levels. No treatment related deaths occurred. The maximum-tolerated dose was determined to be 150 mg p.o. ؋ four doses load and 100 mg p.o. once daily maintenance. Dose-limiting toxicities such as nausea, diarrhea, dehydration, and fatigue were seen early during the loading phase and were surmountable with the use of prophylactic 5-HT 3 receptor antagonists, dexamethasone, and loperamide. Toxicities during the chronic phase were difficult to manage and, given that pharmacokinetic data showed biologically active serum concentrations (based on preclinical data), raised the question of less frequent maintenance dosing. Pharmacokinetic data confirmed the maintenance of stable drug levels with chronic dosing and the long half-life. One partial response was seen, as were multiple patients with stable disease beyond course 2. These results suggest perifosine activity in sarcoma and perhaps renal cell carcinoma (stable disease in two patients who continued for 6 and 14 courses), thus justifying additional investigation of this agent in a phase II sarcoma trial.
The MTD and recommended phase II dose of flavopiridol given by this schedule is 40 mg/m(2)/24 h. The manageable gastrointestinal toxicity, early signs of clinical activity and lack of hematologic toxicity make further exploration in combination trials warranted.
Purpose: To define the toxicities, pharmacodynamics, and clinical activity of the proteasome inhibitor, PS-341 (bortezomib), in patients with advanced malignancies. Patients and Methods: Twenty-eight patients (14 male and 14 female) received PS-341twice weekly for 4 of 6 weeks (schedule I). Because toxicity necessitated dose omissions on this schedule, 16 additional patients (12 male and 4 female) received PS-341 twice weekly for 2 of every 3 weeks (schedule II). A total of 73 courses of treatment was given (median, 2; range, 1-4). Inhibition of 20S proteasome activity in peripheral blood mononuclear cells (PBMC) and accumulation of proteasome-targeted polypeptides in tumor tissue were evaluated as pharmacodynamic markers of PS-341activity. Results: The most common toxicity was thrombocytopenia, which was dose limiting at1.7 mg/m 2 (schedule I) and 1.6 mg/m 2 (schedule II), respectively. Sensory neuropathy was dose-limiting in a patient in schedule I. Grade z 3 toxicities for schedule I were constipation, fatigue, myalgia, and sensory neuropathy. Grade z3 toxicities for schedule II were dehydration resulting from diarrhea, nausea and vomiting, fatigue, hypoglycemia, and hypotension. The maximum tolerated dose was 1.5 mg/m 2 for both schedules. Reversible dose-dependent decreases in 20S proteasome activity in PBMCs were observed, with 36% inhibition at 0.5 mg/m 2 , 52% at 0.9 mg/m 2 , and 75% at 1.25 mg/m 2
Purpose: Prinomastat is a matrix metalloprotease (MMP) inhibitor with selectivity for MMPs 2, 3, 9, 13, and 14. Inhibition of these MMPs has been postulated to block tumor invasion and metastasis. This Phase I, dose-escalation study was designed to evaluate the acute and chronic toxicities of various doses of prinomastat and to determine prinomastat pharmacokinetics.Experimental Design: Seventy-five patients with advanced cancer were given 1, 2, 5, 10, 25, 50, or 100 mg prinomastat orally twice daily until tumor progression or development of significant toxicities. Prinomastat pharmacokinetics were measured on day 29 of therapy.Results: The primary toxicities identified were joint and muscle-related pain, which were generally reversible with treatment rest and/or dose reduction. No dose-limiting toxicities were noted within the first 4 weeks of treatment, but grade 2-3 arthralgias and myalgias were noted 2-3 months after initiation of therapy in >25% of patients at doses >25 mg twice a day. The frequency and severity of symptoms were dose related. Plasma prinomastat concentrations greater than the K i for MMPs 2 and 9 were achieved at all of the dose levels.Conclusions: Doses of 5-10 mg bid were recommended for additional trials, because this dose range was well tolerated for a treatment duration of at least 3 months and achieves trough plasma concentrations 10 -100-fold greater than the K i (in vitro inhibition constant) for the targeted MMPs (2 and 9).
Background Sunitinib treatment results in a compensatory increase in plasma VEGF levels. Acute withdrawal of sunitinib results in a proliferative withdrawal flare, primarily due to elevated VEGF levels. Concurrent sunitinib plus bevacizumab is poorly tolerated with high (37 %) incidence of microangiopathic hemolytic anemia (MAHA). We evaluated a sequential design administering bevacizumab during the sunitinib treatment break to suppress the sunitinib withdrawal flare. Methods Patients with no prior VEGF treatment were enrolled in this study. All patients had target lesions amenable to serial FLT PET/CT imaging. Sunitinib 37.5 mg was given on days 1–28 every 6 weeks with bevacizumab 5 mg/kg on day 29. If safe and tolerable, sunitinib increased to 50 mg. FLT PET/CT scans would be obtained at baseline (D1), week 4, and week 6 to evaluate pharmacodynamics of the sequential combination. Sunitinib pharmacokinetics and total, free, and bound VEGF levels were obtained on each cycle at D1, pre-bevacizumab (D29), 4 h post-bevacizumab (D29H4), and day 42 (D42). Results Six patients enrolled in the safety cohort of sunitinib 37.5 mg plus bevacizumab (see Table). One patient experienced grade 1 MAHA, and after discussion with the Cancer Therapy Evaluation Program (CTEP), the trial was closed to further accrual. No imaging scans were obtained due to early closure. Total and free VEGF levels during cycle 1 Cycle 1 Total VEGF (pg/mL)Mean ± SD Free VEGF (pg/mL)Mean ± SD D1 80 ± 70 51 ± 47 D29 150 ± 62 103 ± 35 D29H4 10 ± 12 2 ± 5 D42 177 ± 34 97 ± 18 Conclusions Subclinical MAHA was seen despite using sequential sunitinib with low-dose bevacizumab, and this combination was not feasible for further development. As predicted, VEGF levels increased during sunitinib exposure followed by a rapid decline after bevacizumab. Due to the long half-life of bevacizumab, we expected VEGF ligand suppression through D42, but instead observed a complete rebound in total/free VEGF levels by D42. The increase in VEGF at D42 was unexpected based on sunitinib alone and contrary to the hypothesis that we would block VEGF flare with low-dose bevacizumab. VEGF ligand production may increase as a result of bevacizumab, implying a robust host compensatory mechanism to VEGF signaling pathway inhibition. A greater understanding of the compensatory mechanism would aid future sequencing strategies of new agents.
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