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Purpose: To evaluate safety, tolerability, and pharmacokinetics of a new nucleoside analogue, tezacitabine [(E)-2'-deoxy-2'-(fluoromethylene)cytidine (FMdC)] in patients with refractory solid tumors., Experimental Design: Seventy patients were enrolled in four separate Phase I trials. Patients had metastatic or relapsed cancer of the colon, breast, pancreas, gastrointestinal tract, lung, and other sites. FMdC was administered by i.v. infusion over 30 min in one of four dose schedules--from once every 3 weeks to twice a week for 3 weeks, with dose escalation in each. Maximum doses ranged from 630 to 16 mg/m(2)., Results: Myelotoxicity, especially neutropenia, was the dominant toxicity and was generally dose-related. Grade 3 or 4 neutropenia occurred in 53% of patients but was of relatively short duration (1-8 days) in all of the patients. One patient experienced grade 3 thrombocytopenia and one patient grade 4 (duration 15 and 11 days, respectively). Transient febrile episodes were reported in 82% of patients with drug administration but were easily controlled. Drug-related gastrointestinal events were mild and appeared unrelated to dose. Pharmacokinetics were linear with dose, not appreciably affected by schedules, and not different after single or multiple doses. Terminal half-life was 3-4 h, and 23% of the administered drug was recovered in the urine as unchanged drug. The uridine analogue (FMdU), the deaminated metabolite of FMdC, was the primary metabolite. Objective antitumor activity was observed in eight patients: one exhibited a partial response and seven exhibited stable disease., Conclusions: In general, FMdC was well tolerated. On the basis of the time to recovery from neutropenia, the recommended schedule for Phase II studies is one treatment every 2 weeks, at a minimum dose of 270 mg/m(2).

An E1B 55 kDa gene-deleted adenovirus, Onyx-015, which reportedly selectively replicates in and lyses p53-deficient cells, was administered by a single intratumoral injection to a total of 22 patients with recurrent head and neck cancer. The objectives of this Phase I study were to determine the safety, feasibility, and efficacy of this therapy and determine any correlation to p53 status. Six cohorts were investigated with a dose escalation from 10(7)-10(11) plaque-forming units. Toxicity was assessed using NCIC criteria. Tumor response was assessed by clinical and radiological measurement. Blood samples were taken to detect adenovirus DNA and neutralizing antibody to adenovirus. Tumor biopsies were taken to detect adenovirus by in situ hybridization. Treatment was well tolerated, with the main toxicity being grade 1/2 flu-like symptoms. Dose-limiting toxicity was not reached at the highest dose of 10(11) plaque-forming units. Twenty-one of the 22 patients treated showed an increase in neutralizing antibody to adenovirus. In situ hybridization showed viral replication in 4 of 22 patients treated, all of whom had mutant p53 tumors. Using conventional response criteria, no objective responses were observed. However, magnetic resonance imaging scans were suggestive of tumor necrosis at the site of viral injection in five patients, three of whom were classified using nonconventional criteria as partial responders, and two of whom were classified using nonconventional criteria as minor responders. Of these five cases, four had mutant p53 tumors. The response duration for the three partial responders was 4, 8, and 12 weeks. An additional eight patients had stable disease in the injected tumors lasting from 4-8 weeks. These preliminary results show that intratumoral administration of Onyx-015 is feasible, well tolerated, and associated with biological activity. Further investigation of Onyx-015, particularly with a more frequent injection protocol and in combination with systemic chemotherapy, is warranted.

A Phase I and pharmacological study was performed to evaluate the feasibility, maximum tolerated dose (MTD), dose-limiting toxicities (DLTs), and pharmacokinetics of the anthrapyrazole losoxantrone in combination with paclitaxel in adult patients with advanced solid malignancies. Losoxantrone was administered as a 10-min infusion in combination with paclitaxel on either a 24- or 3-h schedule. The starting dose level was 40 mg/m2 losoxantrone and 135 mg/m2 paclitaxel (as a 24- or 3-h i.v. infusion) without granulocyte colony-stimulating factor (G-CSF). Administration of these agents at the starting dose level and dose escalation was feasible only with G-CSF support. The following dose levels (losoxantrone/paclitaxel, in mg/m2) of losoxantrone and paclitaxel as a 3-h infusion were also evaluated: 50/135, 50/175, 50/200, 50/225, and 60/225. The sequence-dependent toxicological and pharmacological effects of losoxantrone and paclitaxel on the 24- and 3-h schedules of paclitaxel were also assessed. The MTD was defined as the dose at which >50% of the patients experienced DLT during the first two courses of therapy. DLTs, mainly myelosuppression, occurring during the first course of therapy were noted in four of six and five of eight patients treated with 40 mg/m2 losoxantrone and 135 mg/m2 paclitaxel over 24 and 3 h, respectively, without G-CSF. DLTs during the first two courses of therapy were observed in one of six patients at the 50/175 (losoxantrone/paclitaxel) mg/m2 dose level, two of four patients at the 50/200 mg/m2 dose level, one of four patients at the 50/225 mg/m2 dose level, and two of five patients at the 60/225 mg/m2 dose level. The degree of thrombocytopenia was worse, albeit not statistically significant, when 24-h paclitaxel preceded losoxantrone, with a mean percentage decrement in platelet count during course 1 of 80.7%, compared to 43.8% with the reverse sequence (P = 0.19). Losoxantrone clearance was not significantly altered by the sequence or schedule of paclitaxel. Cardiac toxicity was observed; however, it was not related to total cumulative dose of losoxantrone. An unacceptably high rate of DLTs at the first dose level of 40 mg/m2 losoxantrone and 135 mg/m2 paclitaxel administered as either a 24- or 3-h i.v. infusion precluded dose escalation without G-CSF support. The addition of G-CSF to the regimen permitted further dose escalation without reaching the MTD. Losoxantrone at 50 mg/m2 followed by paclitaxel (3-h i.v. infusion) at 175 mg/m2 with G-CSF support is recommended for further clinical trials.

Prolonged exposure to topotecan in in vitro and in vivo experiments has yielded the highest antitumor efficacy. An oral formulation of topotecan with a bioavailability of 32-44% in humans enables convenient prolonged administration. Pharmacokinetic/pharmacodynamic relationships from four Phase I studies with different schedules of administration of oral topotecan in 99 adult patients with malignant solid tumors refractory to standard forms of chemotherapy were compared. Topotecan was administered as follows: (a) once daily (o.d.) for 5 days every 21 days (29 patients); (b) o.d. for 10 days every 21 days (19 patients); (c) twice daily (b.i.d.) for 10 days every 21 days (20 patients); and (d) b.i.d. for 21 days every 28 days (31 patients). Pharmacokinetic analysis was performed in 55 patients using a validated high-performance liquid chromatographic assay and noncompartmental pharmacokinetic methods. Totals of 109, 48, 64, and 59 courses were given, respectively. Dose-limiting toxicity consisted of granulocytopenia for the o.d. x 5-day dosage, a combination of myelosuppression and diarrhea in both of the 10-day schedules, and only diarrhea in the 21-day schedule. Pharmacokinetics revealed a substantial variation of the area under curve (AUC) of topotecan lactone in all of the dose schedules with a mean intrapatient variation of 25.4 +/- 31.0% (o.d. x 5), 34.5 +/- 25.0% (o.d. x 10), 96.5 +/- 70.1% (b.i.d. x 10), and 59.5 +/- 51.0% (b.i.d. x 21). Significant correlations were observed between myelotoxicity parameters and AUC(t) day 1 and AUC(t) per course of topotecan lactone. In all of the studies, similar sigmoidal relationships could be established between AUC(t) per course and the percentage decrease of WBCs. At maximum-tolerated dose level, no significant difference in AUC(t) per course was found [AUC(t) per course was 107.4 +/- 33.7 ng x h/ml (o.d. x 5), 145.3 +/- 23.8 ng x h/ml (o.d. x 10), 100.0 +/- 41.5 ng x h/ml (b.i.d. x 10), and 164.9 +/- 92.2 ng x h/ml (b.i.d. x 21), respectively.] For oral topotecan, the schedule rather than the AUC(t)-per-course seemed to be related to the type of toxicity. Prolonged oral administration resulted in intestinal side effects as a dose-limiting toxicity, and short-term administration resulted in granulocytopenia. On the basis of this pharmacokinetic study, no schedule preference could be expressed, but based on patient convenience, administration once daily for 5 days could be favored.

Prolonged exposure to topotecan (TPT) in in vitro experiments and in vivo studies in animals yielded the highest antitumor efficacy. An oral bioavailability of TPT of 32-44% enables convenient prolonged administration. Because of unpredictable diarrhea in the third week of the twice daily (b.i.d.) 21-day schedule of p.o. administered TPT and the finding of optimal down-regulation of topoisomerase I level after 10-14 days in mononuclear peripheral blood cells, a shorter period of administration (10 days) was chosen for Phase I and pharmacological studies of oral administration of TPT. Adult patients with malignant solid tumors that were refractory to standard forms of chemotherapy were entered. Two dose schedules were studied: once daily (o.d.) and b.i.d. administration for 10 days every 3 weeks. TPT o.d. for 10 days was studied at dose levels 1.0, 1.4, and 1.6 mg/m2/day, and dose levels were 0.5, 0.6, 0.7, and 0.8 mg/m2 with the 10-day b.i.d. schedule. Pharmacokinetics were performed on days 1 and 8 of the first course using a validated high-performance liquid chromatographic assay and noncompartmental pharmacokinetic methods. Nineteen patients were entered in the 10-day o.d. schedule, with a total of 48 courses given. Dose-limiting toxicity (DLT) was reached at 1.6 mg/m2/day and consisted of common toxicity criteria (CTC) grade IV thrombocytopenia and CTC grade III diarrhea. The maximum tolerated dose was 1.4 mg/m2/day. In the 10-day b.i.d. administration of TPT, a total of 64 courses were studied in 20 patients. DLT was reached at a dose of 0.8 mg/m2 b.i.d. and consisted of CTC grade IV myelosuppression and CTC grade IV diarrhea. The maximum tolerated dose was 0.7 mg/m2 b.i.d. Nonhematological toxicities with both schedules included mild nausea and vomiting, fatigue, and anorexia. Pharmacokinetics revealed a substantial variation of the area under the plasma concentration-time curve of TPT lactone in both schedules. Significant correlations were observed between the myelotoxicity parameters and the area under the plasma concentration-time curve at day 1 of TPT lactone o.d. and b.i.d. The DLT of 10 daily administrations of oral topotecan every 3 weeks consisted of a combination of myelosuppression and diarrhea for both schedules studied. The recommended doses for Phase II studies are 1.4 mg/m2/day for 10 days for the o.d. administration and 0.7 mg/m2 for the b.i.d. schedule.