Biomedical subjects

James P Thomas

Publications and source records attributed to James P Thomas.

7 recordsLinked to original sources

PubMed2003

Phase I pharmacokinetic and pharmacodynamic study of recombinant human endostatin in patients with advanced solid tumors.

PURPOSE: Endostatin is the first endogenous angiogenesis inhibitor to enter clinical trials. Laboratory investigations with endostatin have indicated broad antitumor activity coupled with remarkably low toxicity. A phase I trial of recombinant human endostatin was designed to evaluate toxicity and explore biologic effectiveness in patients with refractory solid tumors. PATIENTS AND METHODS: Endostatin was administered as a 1-hour intravenous infusion given daily for a 28-day cycle. A starting dose of 30 mg/m2 was explored with subsequent dose escalations of 60, 100, 150, 225, and 300 mg/m2. Assessment of serum pharmacokinetics was performed on all 21 patients. Western blot assay and mass spectroscopy were employed to evaluate endostatin metabolism. Circulating levels of endogenous proangiogenic growth factors were examined. Tumor and tumor blood supply were imaged by dynamic computed tomography (CT), magnetic resonance imaging, ultrasound, and positron emission tomography. RESULTS: Endostatin given on this schedule was essentially free of significant drug-related toxicity. Two transient episodes of grade 1 rash were observed. No clinical responses were observed. Endostatin pharmacokinetics were linear with dose, and serum concentrations were achieved that are associated with antitumor activity in preclinical models. No aggregate effect on circulating proangiogenic growth factors were seen, although several patients exhibited persistent declines in vascular endothelial growth factor levels while enrolled in the study. A few patients demonstrated changes in their dynamic CT scans suggestive of a decline in microvessel density, although overall, no consistent effect of endostatin on tumor vasculature was seen. CONCLUSION: Endostatin given daily as a 1-hour intravenous infusion was well tolerated without dose-limiting toxicity at doses up to 300 mg/m2.

Adult↗

PubMed2003

Dual nonlinearities regulate contrast sensitivity in pattern discrimination tasks.

Many current psychophysical models propose that visual processing in cortex is hierarchical, with nonlinearities sandwiched between linear stages of processing. In earlier publications, we proposed a model of this type to account for masking effects found with spatial frequency and orientation discriminations. Our model includes two nonlinear mechanisms that regulate contrast sensitivity in early cortical mechanisms. The first is a local within-pathway nonlinearity that accelerates at low contrasts but is compressive at high. The second is a pooled nonlinear gain control process that operates over a broad range of neurons with different tuning characteristics. Here, we test predictions of the model for spatial frequency discriminations. The model predicts that at low contrasts, adding a grating mask oriented parallel to test gratings will improve discrimination performance via operation of the within-pathway nonlinearity, analogous to the "dipper effect" found with contrast discriminations. Adding an orthogonally oriented mask is predicted to have no effect at low contrasts, where pooled gain control processes contribute little to performance. At high contrasts, the model predicts that performance will asymptote and become independent of contrast with either parallel or orthogonal masks. The results confirm model predictions.

Adult↗

PubMed2003

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.

Adult↗

PubMed2002

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.

Adult↗

PubMed2002

Phase III study of gemcitabine in combination with fluorouracil versus gemcitabine alone in patients with advanced pancreatic carcinoma: Eastern Cooperative Oncology Group Trial E2297.

PURPOSE: Gemcitabine is generally considered to constitute first-line therapy for pancreatic cancer. To determine whether the addition of fluorouracil (5-FU) improves on the results from single-agent gemcitabine, the Eastern Cooperative Oncology Group (ECOG) compared gemcitabine plus bolus 5-FU with gemcitabine alone for patients with advanced pancreatic carcinoma. PATIENTS AND METHODS: This trial involved patients with biopsy-proven, advanced carcinoma of the pancreas not amenable to surgical resection. Patients were randomized to receive either gemcitabine alone (1,000 mg/m(2)/wk) weekly for 3 weeks of every 4 or to receive gemcitabine (1,000 mg/m(2)/wk) followed by 5-FU (600 mg/m(2)/wk) weekly on the same schedule. The primary end point of the trial was survival, with secondary end points of time to progression and response rate. RESULTS: Of 327 patients enrolled over 18 months, 322 were eligible. Overall, the median survival was 5.4 months for gemcitabine alone and 6.7 months for gemcitabine plus 5-FU (P =.09). Progression-free survival for gemcitabine alone was 2.2 months, compared with 3.4 months for gemcitabine plus 5-FU (P =.022). Objective responses were uncommon and were observed in only 5.6% of patients treated with gemcitabine and 6.9% of patients treated with gemcitabine plus 5-FU. Most toxicities were hematologic or gastrointestinal; no significant differences were noted between the two treatment arms. CONCLUSION: 5-FU, administered in conjunction with gemcitabine, did not improve the median survival of patients with advanced pancreatic carcinoma compared with single-agent gemcitabine. Further studies with other combinations of gemcitabine and 5-FU are not compelling, and clinical trial resources should address other combinations and novel agents.

Adult↗

PubMed2002

Phase I study of eniluracil, oral 5-fluororacil and gemcitabine in patients with advanced malignancy.

PURPOSE: The objectives of this trial were to assess the maximal tolerated dose and toxicity of the combination of oral eniluracil and 5-fluorouracil and intravenous gemcitabine. PATIENTS AND METHODS: Patients with histologically confirmed, incurable malignancy (solid tumor or lymphoma) refractory to standard therapy or for which no standard therapy exists were enrolled. The treatment plan consisted of weekly gemcitabine for three weeks with twice daily dosing of 5-FU and eniluracil for 21 days beginning on day one of gemcitabine. Cycles repeated on an every four week schedule. The initial cohort received gemcitabine 800 mg/m2, oral 5-FU 0.6 mg/m2 and eniluracil 6.0 mg/m2. RESULTS: Twenty-six patients were enrolled. Eight patients received less than 2 cycles of therapy. Hematologic and gastrointestinal toxicity predominated, with 48% of courses resulted in grade one or two neutropenia. Hematologic toxicity was dose limiting. One treatment related death occurred. CONCLUSIONS: The combination of eniluracil, 5-fluorouracil and gemcitabine offers an oral alternative for 5-FU administration. The recommended phase II dose is gemcitabine 1000 mg/m2, 5FU 1.2 mg/m2 and eniluracil 12 mg/m2.

Administration, Oral↗

PubMed2002

Phase II trial of perillyl alcohol in patients with metastatic colorectal cancer.

PURPOSE: This is a phase II study of perillyl alcohol in the treatment of patients with metastatic colorectal carcinoma. The primary endpoint is time to progression. Secondary objectives are to evaluate objective response rate and toxicity. PATIENTS AND METHODS: Eligible patients had metastatic adenocarcinoma of the colon or rectum. Patients received perillyl alcohol orally at a dose of 1200 mg/m2. Dose escalation to 1,600 mg/m2 was allowed. RESULTS: Twenty-seven patients were enrolled. The median time to progression was 1.8 months (range 1 to 3 mo). Four patients received less than one cycle and were not evaluable for response. Of the remaining 23, all had progressive disease. There were no complete or partial responses. Toxicity was relatively mild, with fatigue, nausea and anemia predominating. Three patients withdrew from therapy for toxicity (grade 3 belching, bloating; grade 2 nausea, fatigue, vomiting, anorexia and increase perspiration; grade 1 anorexia). DISCUSSION: Despite preclinical evidence of anticancer activity, oral perillyl alcohol administered at this dose and formulation does not appear to have clinical antitumor activity when used for patients with advanced colorectal carcinoma.

Administration, Oral↗