Pharmacodynamic study using FLT PET/CT in advanced solid malignancies treated with a sequential combination of X-82 and docetaxel.

BACKGROUND: A sequential approach, synchronizing cell-cycle specific chemotherapy during VEGFR-TKI treatment breaks, may improve the therapeutic index of this combination therapy. In this study we investigate the safety/tolerability and pharmacodynamic effects of docetaxel used in sequential combination with the novel VEGFR-TKI X-82. METHODS: Patients with advanced solid malignancies underwent 21-day treatment cycles with X-82 administered daily on days 1-14, a treatment break on days 15-20, and docetaxel administered on day 21. Randomization was 1:1 to either a low-dose X-82 (200 mg) or high-dose X-82 (400 mg) arm. Patients were scheduled to undergo four 3'-deoxy-3'-18F-fluorothymidine (FLT) PET/CT scans to assess changes in tumor cell proliferation. PET standardized uptake values (SUV) were summarized for tumors and changes were assessed using mixed effects models. RESULTS: 14 patients were enrolled and treated with median 3.5 cycles (range 0-12). Three patients in the high-dose cohort (50%) and three patients in the low-dose cohort (38%) experienced at least one grade 3 adverse event during the study (infections, cytopenias, electrolyte abnormalities, and vascular complications). Four patients with 13 metastatic tumors underwent FLT PET/CT scanning. During the cycle 1 X-82 exposure period, tumor SUVmax decreased by - 11% (p = 0.04). After administration of docetaxel and the cycle 2 X-82 exposure period, tumor SUVmax decreased - 44% (p = 0.03). CONCLUSIONS: The sequential combination of X-82 and docetaxel was safe and led to diminished FLT uptake. Further, decrease in FLT uptake during cycle 2 (X-82 plus docetaxel) was greater than in cycle 1 (X-82 alone), suggesting sequential chemotherapy enhances the pharmacodynamic effect of therapy.

A phase I pharmacodynamic trial of sequential sunitinib with bevacizumab in patients with renal cell carcinoma and other advanced solid malignancies.

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.

A phase I pharmacodynamic trial of bortezomib in combination with doxorubicin in patients with advanced cancer.

PURPOSE: This phase I trial sought to define the toxicity, maximally tolerated dose (MTD) and pharmacodynamics of a combination of bortezomib and doxorubicin in patients with advanced malignancies. PATIENTS AND METHODS: Twenty-six patients were treated with bortezomib intravenously on days 1, 4, 8 and 11, with doxorubicin also administered intravenously on days 1 and 8, both in a 21-day cycle. Dosing ranged from 1.0 mg/m(2) of bortezomib with 15 mg/m(2) of doxorubicin to 1.5 mg/m(2) of bortezomib with 20 mg/m(2) of doxorubicin. Pharmacodynamic studies performed included assessment of levels of 20S proteasome activity and ubiquitin-protein conjugates. RESULTS: The combination of bortezomib and doxorubicin was generally well tolerated. There were two dose limiting toxicities (DLT) at dose cohort 3 (1.3 mg/m(2) bortezomib, 20 mg/m(2) doxorubicin) and 2 DLT at dose cohort 3a (1.5 mg/m(2) bortezomib, 15 mg/m(2) doxorubicin). DLT seen included neutropenia, thrombocytopenia, and neuropathy. In addition, one patient developed grade 3 central nervous system toxicity in cycle 2 (not a DLT). One patient with hormone refractory prostate cancer had a partial response. Proteasome inhibition in whole blood was demonstrated and an increase in ubiquitin-protein conjugates was observed in peripheral blood mononuclear cells of most patients. CONCLUSIONS: Bortezomib and doxorubicin can be administered safely. The recommended phase II dose for this 21-day cycle is bortezomib 1.3 mg/m(2 )intravenously on days 1, 4, 8 and 11, and doxorubicin 20 mg/m(2) intravenously on days 1 and 8. This combination may be of special interest in multiple myeloma, given the activity of both drugs in that disease.

Phase I trial of weekly paclitaxel and BMS-214662 in patients with advanced solid tumors.

PURPOSE: To assess the maximum tolerated dose (MTD), dose-limiting toxicity (DLT), pharmacodynamics, and antitumor activity of continuous weekly-administered paclitaxel and BMS-214662, a novel farnesyl transferase inhibitor. EXPERIMENTAL DESIGN: Patients were treated every week as tolerated with i.v. paclitaxel (fixed dose, 80 mg/m(2)/wk) administered over 1 h followed by i.v. BMS-214662 (escalating doses, 80-245 mg/m(2)/wk) over 1 h starting 30 min after completion of paclitaxel. RESULTS: Twenty-six patients received 94 courses (one course, 21 days) of study treatment. Two patients received five courses of BMS-214662 as a weekly 24-h infusion (209 mg/m(2)/wk). The most common toxicities were grade 1 to 2 nausea/vomiting and/or diarrhea. DLTs observed at or near the MTD (200 mg/m(2)/wk) were grade 4 febrile neutropenia with sepsis occurring on day 2 of course 1 (245 mg/m(2)/wk), reversible grade 3 to 4 serum transaminase increases on day 2, and grade 3 diarrhea (200 and 245 mg/m(2)/wk). Objective partial responses were observed in patients with pretreated head and neck, ovarian, and hormone-refractory prostate carcinomas, and leiomyosarcoma. The observed pharmacokinetics of paclitaxel and BMS-214662 imply no interaction between the two. Significant inhibition (>80%) of farnesyl transferase activity in peripheral mononuclear cells was observed at the end of BMS-214662 infusion. CONCLUSIONS: Pretreated patients with advanced malignancies can tolerate weekly paclitaxel and BMS-214662 at doses that achieve objective clinical benefit. Due to multiple DLTs occurring at the expanded MTD, the recommended phase 2 dose and schedule is paclitaxel (80 mg/m(2) over 1 h) and BMS-214662 (160 mg/m(2) over 1 h) administered weekly.

Phase I trial of perillyl alcohol administered four times daily continuously.

PURPOSE: Previous experience with perillyl alcohol (POH) was with a formulation of 500-mg capsules each containing 250 mg POH and soybean oil. This formulation resulted in the ingestion of large amounts of soybean oil (>10 g/day). Dose-limiting toxicities (DLT) were primarily gastrointestinal. Prior studies also showed no further increase in POH metabolite concentrations with doses of >1600 mg/m2. Therefore, a new formulation of POH was developed (700 mg containing 675 mg POH) in an effort to improve dose and metabolite concentrations delivered and toxicity encountered with chronic dosing. EXPERIMENTAL DESIGN: Eligible patients had refractory solid malignancies. Dose escalation occurred in cohorts of three at the dose levels/dose of 1350 mg, 2025 mg, 2700 mg, 3375 mg and 4050 mg, administered orally four times a day in a 28-day cycle. RESULTS: A group of 19 patients were enrolled. One DLT occurred at dose level 5. This cohort was expanded to six patients, and no further DLT occurred. The maximum tolerated dose was not reached. The predominant toxicity was gastrointestinal. Nausea and vomiting occurred in 63% of patients (12/19, grade 1 in 10). The same proportion of patients (12/19) experienced heartburn and indigestion, primarily grade 1. Although the side effects were mild in nature, three patients withdrew from treatment, citing intolerable gastrointestinal toxicity. The AUCs of POH metabolites did not appear to increase from level 1 to level 2 or change significantly from day 1 to day 29. Inter- and intrapatient variability in metabolite levels was observed. CONCLUSIONS: This reformulation of POH appears to be an improvement upon the prior formulation, by reducing the number of capsules ingested and the degree of gastrointestinal toxicity per dose. It does not appear to offer any metabolite pharmacokinetic advantage. A dose of 2050 mg administered four times daily was easily tolerated. Higher doses can be administered but with increasing gastrointestinal toxicity that limits compliance.

Gemcitabine, Paclitaxel, and piritrexim: a phase I study.

Piritrexim is a new antifolate that has shown activity in methotrexate-resistant tumors. Gemcitabine is an antimetabolite similar in structure to cytosine arabinoside with early studies demonstrating activity in a variety of cancers. It also has apparent synergistic activity with antifolates from initial work in tumor models. Paclitaxel is an antimicrotubule agent that has a wide spectrum of activity against a variety of solid tumors. The combination of gemcitabine, paclitaxel, and piritrexim was assessed in this phase I trial. Thirty patients were enrolled. The starting doses were piritrexim 25 mg orally twice daily (days 1-4, 15-18), paclitaxel 75 mg/m2 (days 1, 15), and gemcitabine 750 mg/m2 (days 1, 15), which then was escalated in a stepwise fashion. Four patients achieved stable disease while on study, whereas one patient with a poorly differentiated neuroendocrine tumor achieved a partial response. The main toxicity was myelosuppression. The maximum tolerated dose was thought to be piritrexim 25 mg orally three times daily (days 1-4), paclitaxel 150 to 175 mg/m2 (days 1, 15), and gemcitabine 1,000 mg/m2 (days 1, 15). The combination of these new antifolates with paclitaxel and gemcitabine appears safe and should be considered for phase II trials in known responsive tumors such as transitional cell carcinomas.

Phase I clinical and pharmacokinetic trial of the cyclin-dependent kinase inhibitor flavopiridol.

PURPOSE: Flavopiridol (NSC 649890) is a synthetic flavone possessing significant antitumor activity in preclinical models. Flavopiridol is capable of inducing cell cycle arrest and apoptosis, presumably through its potent, specific inhibition of cyclin-dependent kinases. We conducted a phase I trial and pharmacokinetic study of flavopiridol given as a 72-h continuous intravenous infusion repeated every 2 weeks. METHODS: A total of 38 patients were treated at dose levels of 8, 16, 26.6, 40, 50 and 56 mg/m(2)/24 h. During the first infusion, plasma was sampled at 24, 48 and 72 h to determine steady-state concentrations, and peripheral blood lymphocytes were assessed by flow cytometry for evidence of apoptosis. Additional postinfusion pharmacokinetic sampling was done at the 40 and 50 mg/m(2)/24 h dose levels. RESULTS: Gastrointestinal toxicity was dose limiting, with diarrhea being the predominant symptom. Symptomatic orthostatic hypotension was also frequently noted. Several patients experienced tumor-specific pain during their infusions. The maximum tolerated dose (MTD) was determined to be 40 mg/m(2)/24 h. A patient with metastatic gastric cancer at this dose level had a complete response and remained disease-free for more than 48 months after completing therapy. Plasma concentrations at 24 h into the infusion were 94% of those achieved at steady state. Steady-state plasma flavopiridol concentrations at the MTD were 416.6+/-98.9 micro M. These concentrations are at or above those needed to see cell cycle arrest and apoptosis in vitro. The mean clearance of flavopiridol over the dose range was 11.3+/-3.9 l/h per m(2), similar to values obtained preclinically. Elimination was biphasic. The terminal half-life at the MTD was 26.0 h. No significant differences in pharmacokinetic parameters were noted between males and females. Patients taking cholestyramine to ameliorate flavopiridol-induced diarrhea had lower steady-state plasma concentrations. There was no significant change in the cell cycle parameters of peripheral blood lymphocytes analyzed by flow cytometry. CONCLUSIONS: 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.

Phase I clinical and pharmacokinetic study of oral penclomedine (NSC 338720) in adults with advanced solid malignancy.

Penclomedine is a synthetic alpha-picoline derivative that has shown antitumor activity both in preclinical development and in Phase I work using an i.v. preparation. The main toxicities seen in those studies were dose dependent and mainly neurocerebellar, with hematological toxicity being far less severe. This Phase I trial of p.o. penclomedine was conducted to potentially alter the toxicity profile and to avoid the neurological side effects seen with i.v. penclomedine. Eligibility criteria included microscopic confirmation of a solid malignancy or lymphoma with a lack of effective anticancer therapy. Twenty patients were enrolled. The median age was 60.5 years, and the median performance status was one. All but one patient had received prior systemic therapy. The starting dose of penclomedine was 200 mg/m(2) p.o. for 5 days, and was escalated according to a traditional Fibonacci sequence until the maximum tolerated dose (MTD) was observed. No treatment-related deaths were observed during the study. The MTD was determined to be 800 mg/m(2) p.o. for 5 days. Dose-limiting toxicities included mainly neurocerebellar symptoms such as ataxia and dysmetria, but neurocortical symptoms, such as confusion, were seen as well. Myelosuppression was less common and resulted in the discontinuation of therapy in only two patients. Pharmacokinetics show that the observed MTD is consistent with the i.v. preparations, and that the bioavailability of p.o. penclomedine is 49 +/- 18%. This regimen can be considered for additional studies in patients with intracranial neoplasms, because good central nervous system penetration is evident. Further development of penclomedine metabolites, such as 4-O-demethylpenclomedine, should be considered to minimize dose-limiting neurotoxicity.