Phase I chemoprevention study of difluoromethylornithine in subjects with organ transplants.

Individuals who receive life-saving organ transplants and the required immunosuppression often develop secondary cancers. One of the most common secondary cancers is nonmelanoma skin cancer in sun-exposed areas. Attempts to prevent these cancers have not been successful. Difluoromethylornithine (DFMO), a suicide inhibitor of ornithine decarboxylase (ODC), is a known experimental cancer prevention agent that is being evaluated in a number of human cancer prevention trials. This report describes a Phase I trial in 18 organ transplant recipients, randomized to 1.0 and 0.5 g of DFMO or a placebo, designed to look at short-term toxicities over 28 days as well as the impact of DFMO on two biological parameters, skin polyamines and 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ODC activity. Blood levels of DFMO were also measured. The results indicate that DFMO was well tolerated over the 28-day period. The TPA-induced ODC activity in 3-mm skin biopsies was significantly lowered by 80 and 67% at the two dose levels. Polyamine levels were not affected significantly except for putrescine at the 0.5-g level. Blood levels of DFMO were about two times higher than expected, based on our prior pharmacokinetic studies. Our studies indicate that DFMO is a reasonable agent that should be tested further in larger Phase 2b trials in this population as a chemopreventive agent. TPA-induced ODC activity appears to be a relevant intermediate biological assay.

Phase I clinical and pharmacokinetic trial of irofulven.

PURPOSE: To evaluate the clinical tolerability of a new schedule of 6-hydroxymethylacylfulvene (irofulven, MGI 114, HMAF, NSC 683863), a semisynthetic sesquiterpene derived from the cytotoxic mushroom metabolite illudin S. Irofulven has been shown to induce DNA damage and apoptosis in vitro and has shown activity in a number of human tumor xenograft models. A number of drug-resistant cell lines including those that express the mdr phenotype, retain sensitivity to irofulven. METHODS: We conducted a phase I trial of irofulven given as an intravenous infusion (30 min) on a daily x5 schedule every 28 days. A total of ten patients were enrolled and treated at three dose levels, 6, 8, and 11 mg/m2 per day. RESULTS: Irofulven reached steady-state concentrations during the 30-min infusions with biexponential kinetics. Irofulven disappeared rapidly from plasma and was detectable for only 15-30 min after the end of the infusion. The mean half-life was 4.91 min and the mean clearance was 4.57 l/mm per m2. Peak plasma concentrations of irofulven of approximately 300 ng/ml were achieved. Pharmacokinetic parameters did not differ significantly from day 1 to day 5. Irofulven was highly emetogenic. Other prominent toxicities included anorexia and fatigue. One case of delayed-onset metabolic acidosis possibly secondary to irofulven was observed. No other renal or metabolic toxicity was encountered. One patient experienced a late-onset grade 3 extravasation skin injury thought to be secondary to extravasation of irofulven. Minimal marrow suppression was observed. No objective tumor responses were observed. CONCLUSIONS: The recommended phase II dose on this schedule is 6 mg/m2.

Bioavailability study of oral liquid and tablet forms of alpha-difluoromethylornithine.

The purpose of this study was to assess the bioavailability of two oral preparations of difluoromethylornithine (DFMO). The current preparation of DFMO is a liquid with a concentration of 0.2 gram/ml that must be drawn up into a syringe and dispensed into a small medicine glass. This form of DFMO causes wastage of the medication. The liquid form also makes compliance and blinding difficult. Recently, a new coated tablet preparation has become available from Ilex Oncology Services (San Antonio, TX). The coated tablets are 0.25 gram and are scored. The tablet form should increase compliance by making it much easier for the subject to take the medication. This report compares the bioavailability of both preparations with the goal of demonstrating equivalence of the preparations. Ten normal subjects entered the cross-over study in which the order in which they would receive the liquid or tablet preparation of DFMO was randomized. The study was designed with the objective of establishing the bioequivalence of a tablet preparation of DFMO at daily dose 0.5 gram/m2 and a liquid preparation of DFMO at the same daily dose. The mean area under the time-by-concentration curves (microM x hours) for the liquid and tablet preparations was 368.2 and 370.4, respectively. The peak concentrations for the liquid and tablet preparations were 47.3 and 48.2 microM, respectively. No statistically significant differences were seen in these parameters, in time to peak concentration, or in serum half-life.

Chemopreventive efficacy of combined piroxicam and difluoromethylornithine treatment of Apc mutant Min mouse adenomas, and selective toxicity against Apc mutant embryos.

Genetic knockout or pharmacological inhibition of cyclooxygenase-2 decreases the number and size of adenomas in mouse models of familial adenomatous polyposis. Epidemiological and clinical studies in humans indicate that the entire class of nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit both COX-1 and COX-2 enzymes are promising colon cancer chemopreventive agents. We used the Apc mutant Min mouse model to test combinations of agents that might maximize preventive benefit with minimal toxicity because they act via different mechanisms. Min mice (n = 144) were exposed to low doses of the nonselective COX inhibitor piroxicam and the ornithine decarboxylase (ODC) inhibitor difluoromethylornithine (DFMO), beginning at the time they were weaned and continuing throughout the duration of the experiment. Piroxicam at 12, 25, and 50 ppm in the diet caused dose-dependent decreases in the number of tumors in the middle and distal portions of the small intestine. This decrease in tumor multiplicity was associated with a striking decrease in the size of those tumors that did grow out. In contrast, none of the doses of piroxicam alone decreased tumor multiplicity in the proximal portion of the intestine (duodenum). Exposure to DFMO (0.5 or 1.0% in water) caused a dose-dependent decrease in tumor multiplicity in the middle and distal portions of the small intestine. However, this decreased multiplicity was not associated with a striking decrease in the size of the tumors. Combined treatment of mice with piroxicam plus DFMO was much more effective than either agent alone and resulted in a significant number of mice totally free of any intestinal adenomas (P < 0.001), in contrast to the 100% incidence and high multiplicity in control Min mice. In addition to this profound effectiveness in reducing tumor number, the few residual tumors in mice treated with the combined drugs were markedly smaller in size than tumors that arose from control Min mice. These experiments suggest that selective COX-2 inhibition combined with ODC inhibition is a very promising approach for colon cancer prevention. These COX-2 and ODC inhibitor drugs were not overtly toxic at the doses used when administered to mice after weaning. However, when treatment was begun in utero, the Mendelian expected progeny ratio of 1:1 that we routinely obtained in untreated control litters was no longer observed. Apc(min)/+ progeny of pregnant dams treated with piroxicam and/or DFMO were reduced in number and their ratio to Apc+/+ progeny was decreased to approximately 0.28:1. Thus, these agents are effective against adenomas that have homozygous mutation of the APC gene and also select against fetuses bearing a heterozygous mutation in the APC gene.

Phase I clinical and pharmacokinetic study of perillyl alcohol administered four times a day.

We conducted a phase I dose-escalation trial of perillyl alcohol (POH; NSC 641066) given p.o. on a continuous four times a day basis to characterize the maximum tolerated dose, toxicities, pharmacokinetic profile, and antitumor activity. Sixteen evaluable patients with advanced refractory malignancies were treated at the following doses: level 1 (L1), 800 mg/m2/dose; L2, 1200 mg/m2/dose; L3, 1600 mg/m2/dose. POH was formulated in soft gelatin capsules containing 250 mg of POH and 250 mg of soybean oil. The predominant toxicities seen were gastrointestinal (nausea, vomiting, satiety, and eructation), which were dose limiting. There appeared to be a dose-dependent increase in levels of the two main metabolites, perillic acid and dihydroperillic acid. No significant differences were seen whether the drug was taken with or without food. There was a trend toward decreasing metabolite levels on day 29 compared with days 1 and 2. Peak metabolite levels were seen 1-3 h post ingestion. Metabolite half-lives were approximately 2 h. Approximately 9% of the total dose was recovered in the urine in the first 24 h, the majority as perillic acid. Evidence of antitumor activity was seen in a patient with metastatic colorectal cancer who has an ongoing near-complete response of > 2 years duration. Several other patients were on study for > or = 6 months with stable disease. The maximum tolerated dose of POH given continuously four times a day was 1200 mg/m2/dose. Gastrointestinal toxicity was dose limiting, although significant interpatient variability in drug tolerance was seen.

Phase I trial of intravenous thymidine and carboplatin in patients with advanced cancer.

PURPOSE: To evaluate the biologic interactions and toxicities of carboplatin combined with a 24-hour infusion of thymidine 75 mg/m(2) in a phase I trial. PATIENTS AND METHODS: Thirty-two patients with cancer refractory to conventional therapy were treated. The first set of patients (n = 7) received thymidine alone 4 weeks before subsequent planned courses of thymidine combined with carboplatin followed (4 weeks) by carboplatin alone. Carboplatin was administered over 20 minutes at hour 20 of the 24-hour thymidine infusion. The carboplatin dose was escalated in patient groups: 200 mg/m(2) (n = 3); 300 mg/m(2) (n = 7); 350 mg/m(2) (n = 4); 400 mg/m(2) (n = 3); 480 mg/m(2) (n = 10); and 576 mg/m(2) (n = 5). At the maximum-tolerated dose (480 mg/m(2)), five patients received combined therapy first and carboplatin alone second, and five patients received carboplatin first and combined therapy second. Maintenance therapy for stable or responding patients was combined therapy. RESULTS: Evaluation demonstrated a trend toward thymidine protection of carboplatin-induced treatment-limiting thrombocytopenia. Neutropenia with carboplatin alone or in combination was negligible. Thymidine alone had no myelosuppressive effects and produced reversible grade 1 or 2 nausea and vomiting (57%), headache (25%), and grade 1 neurotoxicity (22%). Thymidine did not enhance expected carboplatin toxicities. There was no therapy-related infection or bleeding. Analysis of platinum in plasma ultrafiltrate and urine showed no effect by thymidine. Similarly, thymidine pharmacokinetics was not affected by carboplatin. As predicted, nicotinamide adenine dinucleotide levels in peripheral lymphocytes were increased during exposure to carboplatin and/or thymidine but were decreased by carboplatin alone. In three patients with high-grade glioma, responses included one complete remission (21 months) and one partial remission (14 months) at the 480-mg/m(2)-dose level, and disease stabilization (7 months) at the 400-mg/m(2-dose) level. A minor response was observed in a patient with metastatic colon cancer (5 months) at the 480-mg/m(2)-dose level. CONCLUSION: The combination of carboplatin and thymidine as described is well tolerated. The data presented have resulted in a phase II study by the North American Brain Tumor Consortium.

Phase I clinical and pharmacokinetic study of an one-hour infusion of ormaplatin (NSC 363812).

Ormaplatin (NSC 363812, tetraplatin) is a stable platinum (IV) analog which has exhibited activity against cisplatin-resistant cell lines. A phase I trial of ormaplatin administered as a 1-h infusion every 4 weeks was performed. Forty-one patients received 101 cycles of drug over the dose range 4-128 mg/m2. The dose-limiting toxicity was reversible thrombocytopenia and granulocytopenia. Minimal myelosuppression was observed at dose levels < or = 78 mg/m2, while grade 3 or 4 myelosuppression (thrombocytopenia and/or granulocytopenia) was seen in 4/8 patients at 98 mg/m2 and 4/5 patients at 123 mg/m2. Nausea and vomiting was observed at all dose levels but was controlled with antiemetic premedication. Neurotoxicity was observed in 5/41 patients and the incidence appeared related to cumulative dose rather than to dose level or drug clearance. Platinum was measured by furnace atomic absorption spectrophotometry. Ormaplatin-derived plasma ultrafilterable platinum (UF-Pt) exhibited linear pharmacokinetics over the dose range studied. The mean total body clearance of UF-Pt was 135 ml/min/m2 and the mean elimination half-life (t1/2beta) was 13.6 h. Ormaplatin exhibited a high degree of protein binding, with more than 70% of platinum protein bound by the end of the infusion. Urinary excretion of platinum accounted for 37% of the total dose of ormaplatin in 24 hours. A phase II dose of 98 mg/m2 is recommended for testing in a patient population with cisplatin-refractory disease.

A randomized, placebo-controlled trial of low-dose alpha-difluoromethylornithine in individuals at risk for colorectal cancer.

DFMO is an irreversible inhibitor of ornithine decarboxylase (ODC), the key enzyme in mammalian polyamine biosynthesis. The goal of this study was to determine the effects of DFMO 0.5 g/m2/day as a single oral dose on polyamine and ODC levels in rectal, rectosigmoidal, and cecal colonic mucosae of individuals at risk for colon cancer because of a personal history of adenomatous polyps of the colon or a family history of colon cancer in at least one first-degree relative. A second goal was to determine toxicity of this treatment given over 1 year. Forty-five randomized subjects had a flexible sigmoidoscopy with no preparation and a colonoscopy after lavage preparation at baseline, a sigmoidoscopy with no preparation after 3 months, and both procedures (as at baseline) after 12 months, with mucosal biopsies taken from the rectosigmoid area (sigmoidoscopy) or rectal and cecal areas (colonoscopy) for evaluations of ODC and polyamine levels. Significantly decreased levels of putrescine and spermidine were found in rectosigmoid colonic mucosae of DFMO-treated (n = 24) compared with placebo (n = 21) subjects at 3 months (P = 0.03 and 0.04) and 12 months (P = 0.005, P = 0.004). Similar trends, none reaching statistical significance, were found for individual polyamine levels in rectal and cecal mucosae. No significant differences in ODC levels were detected marginally. There was evidence of global suppression of ODC and polyamine levels in the treatment group (P = 0.035). Three DFMO recipients (12.5%) developed clinically noticeable and audiologically demonstrated hearing loss, which was reversible and attributed to DFMO after 3 months (two subjects) and 12 months (one subject). The tissue polyamine changes demonstrated in this study are consistent with findings in other studies in colon and other tissues. The ototoxicity findings here suggest that investigation of other DFMO schedules, such as ones with a drug "holiday," will be a necessary step before Phase III chemoprevention studies can be pursued.

Phase I chemoprevention study of piroxicam and alpha-difluoromethylornithine.

A two-step Phase I study of piroxicam (PXM) and a-difluoromethylornithine (DFMO) alone and in combination was initiated to assess toxicity and the impact of these drugs on several biological markers. In step 1, 12 subjects with a history of skin cancers were assigned to receive PXM 10 mg every day (q.d.) or 10 mg every other day (q.o.d.). The dosage of PXM 10 mg q.o.d. was tolerated. No changes were seen in 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ornithine decarboxylase (ODC) or urinary polyamine levels. Steady-state serum levels of PXM were consistent with the oral dose level. In step 2, 31 subjects with stage 0 or I nonmelanoma skin cancers, stage A or B prostate or colon cancer, or stage I breast cancer or who had a family history of cancer were randomized to receive DFMO 0.5 g/m2, PXM 10 mg q.o.d., or the combination of DFMO and PXM. In addition to the biological markers of TPA-induced ODC activity in skin biopsies and urinary polyamine levels, we measured urinary 11-dehydrothromboxane B2, a specific metabolite of thromboxane A2. Of the 12 subjects on DFMO/PXM, 2 dropped out for non-drug-related reasons. Three developed grade-2 drug-related toxicities. One subject developed dyspnea that resolved and was able to continue on the study for 6 months. One subject who developed diarrhea that resolved after 5 days was also able to restart the drug without a recurrence. A third subject described intermittent episodes of tinnitus starting 4 h after taking PXM that lasted only 5 s and did not progress on treatment. Comparing the 6-month measurements with pretreatment, DFMO/PXM or DFMO significantly reduced TPA-induced ODC levels (Ps, 0.03 and 0.05). Urinary polyamine levels of spermidine decreased slightly with the DFMO/PXM or DFMO alone, whereas putrescine decreased with PXM alone. Levels of 11-dehydrothromboxane B2 were depressed by PXM and PXM/DFMO. The doses of DFMO/PXM determined in step 2 are potential starting dosages for Phase IIa and IIb chemoprevention trials.

Phase I clinical trial of perillyl alcohol administered daily.

Perillyl alcohol (POH; NSC-641066), a naturally occurring monoterpene, has shown antitumor and preventive activity in preclinical studies in rodent models. Drug-related activities that have been observed include the induction of apoptosis, cell cycle arrest, the inhibition of posttranslational modification of proteins that are involved in signal transduction, and differential gene regulation. We treated 18 patients who had advanced malignancies with POH, which was given on a continuous three-times-a-day schedule at the following doses: (a) level 1 (L1), 800 mg/m2/dose; (b) level 2 (L2), 1600 mg/m2/dose; and (c) level 3 (L3), 2400 mg/m2/dose. The main toxicity, which seemed to be dose related, was gastrointestinal and included nausea and vomiting, anorexia, unpleasant taste, satiety, and eructation. Two heavily pretreated ovarian cancer patients experienced reversible > or =grade 3 granulocytopenia. Grade 1-2 fatigue was also noted. The parent drug was not detectable in the plasma. The mean peak plasma levels of the two main metabolites on days 1 and 29 were 175 and 139 microM (L1), 472 and 311 microM (L2), and 456 and 257 microM (L3) for perillic acid (PA) and 7.1 and 9.8 microM (L1), 34.2 and 34.0 microM (L2), and 26.2 and 23.4 microM (L3) for dihydroperillic acid (DHPA). Peak levels were noted 2-3 h postingestion for PA and 3-5 h postingestion for DHPA. Metabolite half-lives measured about 2 h for each. POH, PA, and DHPA were detectable in the urine of all patients at L3. About 9% of the total dose was recovered in the first 24 h. The majority was recovered as PA; less than 1% was recovered as POH. Disease stabilization for > or =6 months was seen, although no objective tumor responses were noted. Further study of POH continues with a more frequent dosing schedule.

Renal clearance, tissue distribution, and CA-125 responses in a phase I trial of suramin.

Suramin was administered to 49 patients in a Phase I cancer trial with real-time pharmacokinetic monitoring and dose individualization to achieve targeted mean plasma concentrations of 210 and 155 mg/liter during the 7-day period between days 15 and 22. Pharmacokinetic sampling after doses on days 1, 3, 5, and 8 was used to modify weekly suramin doses, beginning on day 15, in an attempt to achieve specific averaged plasma concentrations of 210 and 155 mg/liter. A 200-mg test dose was not effective in prospectively determining individual pharmacokinetic parameters and dosage requirements. Patients with peak plasma suramin concentrations in excess of 350 mg/liter may be more likely to experience neurotoxicity (P = 0.06), but there was no statistically significant effect of peak suramin concentration or of cumulative dose. Biopsy and autopsy tissue samples demonstrated low penetration of suramin into brain tissue and muscle but good penetration into prostate and other visceral organs. Prospective use of surrogate substrates for CYP1A2, CYP3A3/4, and CYP2D6 showed no consistent effect of suramin on these enzymes. Although a correlation between creatinine clearance and suramin renal clearance was found (r2 = 0.38; P < 0.00005), there was no correlation between creatinine clearance and total suramin clearance (P = 0.21). No suramin dose modification for renal or hepatic dysfunction can be supported at this time. Three of four ovarian cancer patients demonstrated a drop in CA-125 serum concentrations during suramin treatment.

Phase I clinical and pharmacokinetic trial of penclomedine using a novel, two-stage trial design for patients with advanced malignancy.

PURPOSE: A novel phase I trial design was used to determine the maximum-tolerated dose (MTD) and pharmacokinetics for penclomedine when administered as an intravenous (i.v.) infusion over 1 hour daily for 5 days, repeated every 28 days. This study also tests the feasibility of a novel two-stage design for phase I trials. PATIENTS AND METHODS: Twenty-eight patients with advanced malignancy who met standard eligibility criteria were treated with i.v. penclomedine. The initial daily dose was 50 mg/m2. Dose escalations were planned using a modified Fibonacci sequence. One patient was enrolled on each dose level during the first stage of this trial. In the second stage, patients were enrolled in cohorts of three, proceeding in an up-and-down manner based on toxicities observed. MTD was determined by logistic regression analysis. Pharmacokinetic assessment was performed during the first cycle of treatment. RESULTS: Dose-limiting toxicities (DLT) observed during this trial were principally neurologic and were self-limited. Although hematologic toxicity was rare, the few patients with significant hematologic changes experienced late nadirs with prolonged time to recovery. The MTD was estimated as 381 mg/m2 (80% CI, 343 to 415 mg/m2). Although there was a long elimination half-life, accumulation of penclomedine over the 5 days of administration was negligible. CONCLUSION: The novel trial design used in this study was safe and appeared effective in limiting the numbers of patients treated at lower-dose levels. Reversible neurotoxicity was dose-limiting. Although the estimated MTD was 381 mg/m2, any dose within the CI would be reasonable for phase II study.

Phase I study of continuous-infusion L-S,R-buthionine sulfoximine with intravenous melphalan.

BACKGROUND: Increased intracellular glutathione has long been associated with tumor cell resistance to various cytotoxic agents. An inhibitor of glutathione biosynthesis, L-S,R-buthionine sulfoximine (BSO), has been shown to enhance the cytotoxicity of chemotherapeutic agents in vitro and in vivo. We performed a phase I study of BSO administered with the anticancer drug melphalan to determine the combination's safety/tolerability and to determine clinically whether BSO produced the desired biochemical end point of glutathione depletion (<10% of pretreatment value). METHODS: Twenty-one patients with advanced cancers received an initial 30-minute infusion of BSO totaling 3.0 g/m2 and immediately received a continuous infusion of BSO on one of the following schedules: 1) 0.75 g/m2 per hour for 24 hours (four patients); 2) the same dose rate for 48 hours (four patients); 3) the same dose rate for 72 hours (10 patients); or 4) 1.5 g/m2 per hour for 48 hours (three patients). During week 1, the patients received BSO alone; during weeks 2 or 3, they received BSO plus melphalan (15 mg/m2); thereafter, the patients received BSO plus melphalan every 4 weeks. Glutathione concentrations in peripheral blood lymphocytes were determined for all patients; in 10 patients on three of the administration schedules, these measurements were made in multiple sections from tumor biopsy specimens taken before, during, and after continuous-infusion BSO. RESULTS: Continuous-infusion BSO alone produced minimal toxic effects, although BSO plus melphalan produced occasional severe myelosuppression (grade 4) and frequent low-grade nausea/vomiting (grade 1-2). This treatment also produced consistent, profound glutathione depletion (<10% of pretreatment value). The degree of glutathione depletion in peripheral lymphocytes was considerably less than that observed in tumor sections. CONCLUSIONS: Continuous-infusion BSO is relatively nontoxic and results in depletion of tumor glutathione.

Lack of thermal enhancement for taxanes in vitro.

The taxanes represent a new class of clinical chemotherapeutic agents. A series of in vitro studies were independently of each other initiated in two different institutes (Amsterdam and Madison) to test the hypothesis that hyperthermia might enhance the cytotoxicity of taxanes. Clonogenic capacity experiments (Amsterdam) included the exposure of R1- and SW 1573-cells to 1, 4, or 24 h of paclitaxel with heat 43 degrees C x 60 min in the last hour of drug treatment or at 24, 48 as well as 72 h post drug treatment. Survival assay experiments (Madison) included the exposure of L-929-cells to paclitaxel and docetaxel for 24 h with heat 41.8 degrees C x 60 min the first or last hour of drug treatment as well as 24 and 48 h post treatment. No thermal enhancement of cytotoxicity for the taxanes was observed in these human and murine cell lines, with congruent data in both institutes. In addition, high performance liquid chromatography studies at 41.8 degrees C and 43 degrees C demonstrated paclitaxel and docetaxel were heat stable.

Phase I clinical and pharmacokinetic study of oral carboxyamidotriazole, a signal transduction inhibitor.

PURPOSE: We conducted a phase I trial of carboxyamidotriazole (CAI, NSC 609974), designed to determine the maximum-tolerated dose (MTD), toxicity profile, and pharmacokinetic characteristics of CAI gelatin capsule (gelcap) formulation administered daily as a single oral dose. PATIENTS AND METHODS: Twenty-nine patients with advanced malignancy who met standard eligibility criteria were treated with once-daily CAI given in cycles of 28 days. Pharmacokinetic sampling was performed on days 1 and 29 and trough plasma CAI levels were assessed weekly. RESULTS: Patients were entered at dose levels of 50, 75, and 100 mg/m2. All three patients at the 100-mg/m2 level experienced dose-limiting neurocerebellar toxicity. Other neurotoxicities were mild. Gastrointestinal side effects were common, but generally mild, with 23 patients experiencing nausea and/or vomiting of any grade. Fatigue was a frequent complaint, with 19 patients experiencing mild to moderate symptoms. Six patients with nausea and vomiting and five with fatigue experienced relief of symptoms with a change to nocturnal administration of CAI. Peak plasma concentrations (Cp) occurred at 2.4 +/- 1.5 hours after administration of the oral gelcap dose. Patients approached steady-state trough plasma concentrations (Css) by days 8 to 15 and maintained a relatively constant Css throughout the course of treatment. For all patients, the mean variation in weekly CAI Cp was 12.4% +/- 5.3%. CONCLUSION: The MTD for the gelcap formulation was 75 mg/m2 with dose-limiting neurocerebellar toxicity (ataxia) seen at 100 mg/m2. Other prominent side effects, including nausea, vomiting, and fatigue, were partially alleviated through altering the administration schedule to nighttime dosing.

Phase I clinical trial of melphalan and 41.8 degrees C whole-body hyperthermia in cancer patients.

PURPOSE: To evaluate the biologic interactions and toxicities of melphalan (L-PAM) combined with 41.8 degrees C whole-body hyperthermia (WBH) for 60 minutes. PATIENTS AND METHODS: Sixteen patients with refractory cancer were treated (May 1992 to May 1995) with WBH alone during week 1) thereafter patients were randomized to receive either L-PAM alone on week 2 and L-PAM plus WBH on week 5, or the reverse sequence. Patients who demonstrated clinical improvement received WBH plus L-PAM monthly. Dose levels of L-PAM were 10 mg/m2 (n = 3), 15 mg/m2 (n = 3), 17.5 mg/m2 (n = 6), and 20 mg/m2 (n = 4). L-PAM was administered at target temperature; WBH was administered with an Aquatherm radiant-heat device (patent pending; Cancer Research Institute, New York, NY). RESULTS: Comparisons of mean WBC count and platelet nadirs for L-PAM alone and L-PAM plus WBH demonstrated that the addition of WBH resulted in nadir counts that were, on average, 25% lower. There were no instances of febrile neutropenia or bleeding. Toxicities allowed for escalation of L-PAM to 20 mg/m2; all four patients at this level experienced grade 4 myelosuppression. No significant myelosuppression was observed at 10 and 15 mg/m2. Grade 3 myelosuppression was observed in two of six patients at 17.5 mg/m2. Responses included complete remission (CR) of pancreatic cancer (10 mg/m2), partial remission (PR) of malignant melanoma in two patients (20 mg/m2), and transient clinical and/or serologic improvement in five patients. The pharmacokinetics of L-PAM were not altered by WBH. Observed cytokine induction by WBH is also discussed in detail. CONCLUSION: We conclude that L-PAM with 41.8 degrees C WBH is well tolerated. Clinical results are consistent with preclinical predictions and provide a foundation for second-generation trials now in progress.

Leucovorin modulation of 5-iododeoxyuridine radiosensitization: a phase I study.

Evidence for clinically significant radiosensitization by the halogenated pyrimidine 5-iododeoxyuridine (IdUrd) continues to accumulate. In vitro radiosensitization has been demonstrated in human colon tumor cell lines following exposure to 1-10 micrometer. Coadministration of leucovorin (LV) increases radiosensitization, which correlates directly with increased IdUrd DNA incorporation. Clinical data regarding proliferation rates and thymidine kinase levels in tumors versus normal tissues suggest selective incorporation of IdUrd into gastrointestinal tumors may occur. The objectives of this Phase I study were: (a) to assess the feasibility of LV modulation of IdUrd radiosensitization by determining the maximum tolerated dose (MTD) of IdUrd plus LV; and (b) to perform correlative laboratory studies to investigate the potential of IdUrd plus LV to increase radiosensitization in vivo. Seventeen patients with unresectable or recurrent gastrointestinal adenocarcinomas received a 14-day course of continuous i.v. infusion of IdUrd prior to initiation of radiotherapy. Two additional 14-day infusions of IdUrd with LV were given during the course of radiotherapy (60 Gy in 6 weeks). The initial dose of IdUrd was 250 mg/m2/day and was escalated in subsequent patients to 400 and 600 mg/m2/day. The LV dose remained fixed at 250 mg/m2/day. Leukopenia was the dose-limiting toxicity, and 400 mg/m2/day was the MTD for this trial. At the MTD, the mean +/- SD steady-state plasma concentration of IdUrd during the infusion, measured by high-performance liquid chromatography, was 0.66 +/- 0.23 micrometer. There was no significant influence of LV on IdUrd DNA incorporation in peripheral blood granulocytes as measured by high-performance liquid chromatography. Based on toxicity data and correlative laboratory studies, a meaningful increase in radiosensitization would not be achieved with the IdUrd infusion schedule and dose of LV investigated compared with IdUrd alone.

Chemoprevention of spontaneous intestinal adenomas in the Apc Min mouse model by the nonsteroidal anti-inflammatory drug piroxicam.

C57BL/6J-Min/+mice (n = 56), heterozygous for a nonsense mutation in the Apc gene, were randomized at weaning to seven groups, including groups treated with piroxicam at 0, 50, 100, and 200 ppm in the AIN93G diet. After only 6 weeks of treatment, intestinal adenomas and aberrant crypt foci were counted, and serum levels of piroxicam and thromboxane B2 were quantitated. Tumor multiplicity was decreased in a dose-dependent manner from 17.3 +/- 2.7 in the control to 2.1 +/- 1.1 (12%) in the high-dose piroxicam group (P < 0.001). Thromboxane B2 levels in plasma also decreased monotonically in parallel to the decrease in tumor multiplicity, consistent with the prostaglandin inhibitory effect of piroxicam. The Min mouse model demonstrates that the nonsteroidal anti-inflammatory drug piroxicam has strong biological and therapeutic effects, potentially useful for prevention of the early adenoma stage of tumor development.

Clinical pharmacokinetics of cyclophosphamide and metabolites with and without SR-2508.

The pharmacokinetics of cyclophosphamide (CP) and several important metabolites was studied in detail in six patients receiving CP alone and with a radio- and chemosensitizing agent, SR-2508. CP at 1000 mg/m2 was either infused in 20 min alone or given 2 h before an infusion of SR-2508 at 5 g/m2 over 20 min, both separated by 3 weeks, to the same patients in a randomized fashion. Plasma and 24-h urinary levels of CP and four metabolites: [4-hydroxycyclophosphamide (4-OH CP), phosphoramide mustard (PM), chloroethyl oxazolidin-2-one, and alcophosphamide] were monitored by a gas chromatographic-mass spectrometric-stable isotope dilution assay. CP plasma levels were found to decline monoexponentially with the appearance of transient saturation kinetics in some and a mean t1/2 of 5.2 h for patients treated with CP alone. Plasma 4-OH CP levels showed a mean peak concentration of 2.4 microM and declined approximately in parallel to those of CP. The major circulating metabolite was found to be PM with a mean peak concentration of 40 microM and a terminal t1/2 of 15 h. The mean area under the plasma concentration curve (AUC) ratios between metabolites and CP were: 4-OH CP, 0.0158; PM, 0.4518; and chloroethyl oxazolidin-2-one, 0.179 with alcophosphamide at low levels. No appreciable amount of nornitrogen mustard was detected. Mean urinary excretion was: CP, 10.8; 4-OH, CP, 0.5; PM, 39.0; alcophosphamide, 0.4; and chloroethyl oxazolidin-2-one, 3.0, all expressed as a percentage of CP dose. No statistically significant difference was detected in all standard pharmacokinetic parameters determined for both CP and metabolites between patients with CP alone and with SR 2508. Plasma 4-(p-nitrobenzyl)pyridine activity was found to correlate the closest with PM profiles, with respect to both standard pharmacokinetic parameters and AUC values. When plasma PM AUC values were plotted against AUC values of circulating 4-(p-nitrobenzyl)pyridine activity, a correlation coefficient of 0.859 (P < 0.001) was obtained. Together with the significant cytotoxicity of PM these data support a significant contribution of circulating PM in the antitumor effect of PM.