Phase I and Correlative Biology Study of Cilengitide in Patients With Recurrent Malignant Glioma

Purpose This multi-institutional phase I trial was designed to determine the maximum-tolerated dose (MTD) of cilengitide (EMD 121974) and to evaluate the use of perfusion magnetic resonance imaging (MRI) in patients with recurrent malignant glioma. Patients and Methods Patients received cilengitide twice weekly on a continuous basis. A treatment cycle was defined as 4 weeks. Treatment-related dose-limiting toxicity (DLT) was defined as any grade 3 or 4 nonhematologic toxicity or grade 4 hematologic toxicity of any duration. Results A total of 51 patients were enrolled in cohorts of six patients to doses of 120, 240, 360, 480, 600, 1,200, 1,800, and 2,400 mg/m2 administered as a twice weekly intravenous infusion. Three patients progressed early and were inevaluable for toxicity assessment. The DLTs observed were one thrombosis (120 mg/m2), one grade 4 joint and bone pain (480 mg/m2), one thrombocytopenia (600 mg/m2) and one anorexia, hypoglycemia, and hyponatremia (800 mg/m2). The MTD was not reached. Two patients demonstrated complete response, three patients had partial response, and four patients had stable disease. Perfusion MRI revealed a significant relationship between the change in tumor relative cerebral blood flow (rCBF) from baseline and area under the plasma concentration versus time curve after 16 weeks of therapy. Conclusion Cilengitide is well tolerated to doses of 2,400 mg/m2, durable complete and partial responses were seen in this phase I study, and clinical response appears related to rCBF changes.

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Phase I study of temozolomide in children and adolescents with recurrent solid tumors: a report from the Children's Cancer Group.

Journal of Clinical Oncology ◽

10.1200/jco.1998.16.9.3037 ◽

1998 ◽

Vol 16 (9) ◽

pp. 3037-3043 ◽

Cited By ~ 70

Author(s):

H S Nicholson ◽

M Krailo ◽

M M Ames ◽

N L Seibel ◽

J M Reid ◽

...

Keyword(s):

Phase I ◽

Children And Adolescents ◽

Complete Response ◽

Maximum Tolerated Dose ◽

Hematologic Toxicity ◽

Cancer Group ◽

Grade 3 ◽

Dose Levels ◽

Dose Limiting Toxicity

PURPOSE The Children's Cancer Group conducted a phase I trial of temozolomide stratified by prior craniospinal irradiation (CSI). PATIENTS AND METHODS Children and adolescents with recurrent or progressive cancer were enrolled. Temozolomide was administered orally daily for 5 days, with subsequent courses administered every 21 to 28 days after full hematologic recovery. Dose levels tested included 100, 150, 180, 215, 245, and 260 mg/m2 daily. RESULTS Twenty-seven patients on the non-CSI stratum were assessable for hematologic toxicity. During the first three dose levels (100, 150, and 180 mg/m2 daily), only grades 1 and 2 hematologic toxicity occurred. One patient at 215 mg/m2 daily had grade 3 hematologic toxicity. Three of eight patients (38%) treated at 245 to 260 mg/m2 daily had dose-limiting toxicity (DLT), which included both neutropenia and thrombocytopenia. Twenty-two patients on the CSI stratum were assessable for hematologic toxicity. Hematologic DLT occurred in one of six patients (17%) at 100 mg/m2 daily and in two of four patients (50%) at 215 mg/m2 daily. No nonhematologic DLT occurred; nausea and vomiting occurred in more than half of the patients. After two courses of temozolomide, 10 patients had stable disease (SD), and three patients had a partial response (PR), one of whom subsequently had a complete response (CR) that persists through 24 months of follow-up. CONCLUSION The maximum-tolerated dose (MTD) of temozolomide for children and adolescents without prior CSI is 215 mg/m2 daily and for those with prior CSI is 180 mg/m2 daily for 5 days, with subsequent courses that begin on day 28. Temozolomide is well tolerated and should undergo phase II testing in children and adolescents.

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Phase I Trial of Tipifarnib in Patients With Recurrent Malignant Glioma Taking Enzyme-Inducing Antiepileptic Drugs: A North American Brain Tumor Consortium Study

Journal of Clinical Oncology ◽

10.1200/jco.2005.10.068 ◽

2005 ◽

Vol 23 (27) ◽

pp. 6647-6656 ◽

Cited By ~ 51

Author(s):

Timothy F. Cloughesy ◽

John Kuhn ◽

H. Ian Robins ◽

Lauren Abrey ◽

Patrick Wen ◽

...

Keyword(s):

Malignant Glioma ◽

Antiepileptic Drugs ◽

Mononuclear Cells ◽

Maximum Tolerated Dose ◽

Pharmacokinetic Parameters ◽

Clinical Activity ◽

Recurrent Malignant Glioma ◽

Pharmacokinetics And Pharmacodynamics ◽

Time Curve ◽

Peripheral Blood Mononuclear

Purpose To determine the maximum-tolerated dose (MTD), toxicities, and clinical effect of tipifarnib, a farnesyltransferase (FTase) inhibitor, in patients with recurrent malignant glioma taking enzyme-inducing antiepileptic drugs (EIAEDs). This study compares the pharmacokinetics and pharmacodynamics of tipifarnib at MTD in patients on and off EIAEDs. Patients and Methods Recurrent malignant glioma patients were treated with tipifarnib using an interpatient dose-escalation scheme. Pharmacokinetics and pharmacodynamics were assessed. Results Twenty-three assessable patients taking EIAEDs received tipifarnib in escalating doses from 300 to 700 mg bid for 21 of 28 days. The dose-limiting toxicity was rash, and the MTD was 600 mg bid. There were significant differences in pharmacokinetic parameters at 300 mg bid between patients on and not on EIAEDs. When patients on EIAEDs and not on EIAEDs were treated at MTD (600 and 300 mg bid, respectively), the area under the plasma concentration–time curve (AUC)0-12 hours was approximately two-fold lower in patients on EIAEDs. Farnesyltransferase inhibition was noted at all tipifarnib dose levels, as measured in peripheral-blood mononuclear cells (PBMC). Conclusion Toxicities and pharmacokinetics differ significantly when comparing patients on or off EIAEDs. EIAEDs significantly decreased the maximum concentration, AUC0-12 hours, and predose trough concentrations of tipifarnib. Even in the presence of EIAEDs, the levels of tipifarnib were still sufficient to potently inhibit FTase activity in patient PBMCs. The relevance of these important findings to clinical activity will be determined in ongoing studies with larger numbers of patients.

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Phase I and pharmacologic study of the combination paclitaxel and carboplatin as first-line chemotherapy in stage III and IV ovarian cancer.

Journal of Clinical Oncology ◽

10.1200/jco.1997.15.5.1953 ◽

1997 ◽

Vol 15 (5) ◽

pp. 1953-1964 ◽

Cited By ~ 44

Author(s):

M T Huizing ◽

L J van Warmerdam ◽

H Rosing ◽

M C Schaefers ◽

A Lai ◽

...

Keyword(s):

Ovarian Cancer ◽

Phase I ◽

Residual Disease ◽

Single Agent ◽

Stage Iv ◽

Maximum Tolerated Dose ◽

Stage Iii ◽

Hematologic Toxicity ◽

Time Curve ◽

Second Look

PURPOSE To determine the maximum-tolerated dose for the combination paclitaxel and carboplatin administered every 4 weeks and to gain more insight into the pharmacokinetics and pharmacodynamics of this combination in previously untreated ovarian cancer patients. PATIENTS AND METHODS Thirty-five chemotherapy-naive patients with suboptimally debulked stage III (tumor masses > 3 cm) and stage IV ovarian cancer were entered onto this phase I trial in which paclitaxel was administered as a 3-hour intravenous (IV) infusion at dosages of 125 to 225 mg/m2 immediately followed by carboplatin over 30 minutes at dosages of 300 to 600 mg/m2. A total of six courses was planned, followed by a second-look laparoscopy/laparotomy. Patients with a response and/or minimal residual disease at second-look laparoscopy received three additional courses. Twenty-six patients participated in the pharmacokinetic part of the study. RESULTS The most important hematologic toxicity encountered was neutropenia. Neutropenia was more pronounced for the higher dose levels (DLs) and was cumulative. Thrombocytopenia was mild in the first eight DLs, but increased during the treatment courses. Nonhematologic toxicities consisted mainly of vomiting, neuropathy, fatigue, rash, pruritus, myalgia, and arthralgia. Dose-limiting toxicities (DLTs) in this trial were neutropenic fever, thrombocytopenia that required platelet transfusions, and cumulative neuropathy. Of 33 patients assessable for response, 26 major responders (78%, 20 complete response [CR] and six partial response [PR]) were documented. The maximal concentration (Cmax) of paclitaxel and the area under the concentration-time curve (AUC) were not different from the historical data for paclitaxel as a single agent. Retrospective analysis using a modified Calvert formula showed that the measured carboplatin AUCs in plasma ultrafiltrate (pUF) were 30% +/- 3.4% less than the calculated carboplatin AUC. Neutropenia was more pronounced than could be expected on the basis of the historical times above a threshold concentration greater than 0.1 mumol/L (T > or = 0.1 mumol/L) or 0.05 mumol/L (T > or = 0.05 mumol/L), and thrombocytopenia was less than could be expected from historical sigmoidal Emax models. CONCLUSION The combination of paclitaxel 200 mg/ m2 and carboplatin 550 mg/m2 every 4 weeks is a well-tolerated treatment modality. The paclitaxel-carboplatin combination is highly active in stage III (bulky) and stage IV ovarian cancer. No indications for a pharmacokinetic drug-drug interaction between carboplatin and paclitaxel were found.

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Phase I Trial of Carmustine Plus O6-Benzylguanine for Patients With Recurrent or Progressive Malignant Glioma

Journal of Clinical Oncology ◽

10.1200/jco.2000.18.20.3522 ◽

2000 ◽

Vol 18 (20) ◽

pp. 3522-3528 ◽

Cited By ~ 95

Author(s):

Henry S. Friedman ◽

James Pluda ◽

Jennifer A. Quinn ◽

Reginald B. Ewesuedo ◽

Lina Long ◽

...

Keyword(s):

Phase I ◽

Malignant Glioma ◽

Half Life ◽

Phase I Trial ◽

Maximum Tolerated Dose ◽

Time Curve ◽

Elimination Half Life ◽

Major Mechanism ◽

Elimination Half ◽

The Mean

PURPOSE: The major mechanism of resistance to alkylnitrosourea therapy involves the DNA repair protein O6-alkylguanine-DNA alkyltransferase (AGT), which removes chloroethylation or methylation damage from the O6 position of guanine. O6-benzylguanine (O6-BG) is an AGT substrate that inhibits AGT by suicide inactivation. We conducted a phase I trial of carmustine (BCNU) plus O6-BG to define the toxicity and maximum-tolerated dose (MTD) of BCNU in conjunction with the preadministration of O6-BG with recurrent or progressive malignant glioma. PATIENTS AND METHODS: Patients were treated with O6-BG at a dose of 100 mg/m2 followed 1 hour later by BCNU. Cohorts of three to six patients were treated with escalating doses of BCNU, and patients were observed for at least 6 weeks before being considered assessable for toxicity. Plasma samples were collected and analyzed for O6-BG, 8-oxo-O6-BG, and 8-oxoguanine concentration. RESULTS: Twenty-three patients were treated (22 with glioblastoma multiforme and one with anaplastic astrocytoma). Four dose levels of BCNU (13.5, 27, 40, and 55 mg/m2) were evaluated, with the highest dose level being complicated by grade 3 or 4 thrombocytopenia and neutropenia. O6-BG rapidly disappeared from plasma (elimination half-life = 0.54 ± 0.14 hours) and was converted to a longer-lived metabolite, 8-oxo-O6-BG (elimination half-life = 5.6 ± 2.7 hours) and further to 8-oxoguanine. There was no detectable O6-BG 5 hours after the start of the O6-BG infusion; however, 8-oxo-O6-BG and 8-oxoguanine concentrations were detected 25 hours after O6-BG infusion. The mean area under the concentration-time curve (AUC) of 8-oxo-O6-BG was 17.5 times greater than the mean AUC for O6-BG. CONCLUSION: These results indicate that the MTD of BCNU when given in combination with O6-BG at a dose of 100 mg/m2 is 40 mg/m2 administered at 6-week intervals. This study provides the foundation for a phase II trial of O6-BG plus BCNU in nitrosourea-resistant malignant glioma.

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Phase I Trial of Oral Irinotecan and Temozolomide for Children With Relapsed High-Risk Neuroblastoma: A New Approach to Neuroblastoma Therapy Consortium Study

Journal of Clinical Oncology ◽

10.1200/jco.2008.18.5918 ◽

2009 ◽

Vol 27 (8) ◽

pp. 1290-1296 ◽

Cited By ~ 60

Author(s):

Lars M. Wagner ◽

Judith G. Villablanca ◽

Clinton F. Stewart ◽

Kristine R. Crews ◽

Susan Groshen ◽

...

Keyword(s):

High Risk ◽

Phase I ◽

Phase I Trial ◽

Single Agent ◽

Complete Response ◽

Maximum Tolerated Dose ◽

Time Curve ◽

Disease Stabilization ◽

Heavily Pretreated ◽

Grade 3

PurposeIrinotecan and temozolomide have single-agent activity and schedule-dependent synergy against neuroblastoma. Because protracted administration of intravenous irinotecan is costly and inconvenient, we sought to determine the maximum-tolerated dose (MTD) of oral irinotecan combined with temozolomide in children with recurrent/resistant high-risk neuroblastoma.Patients and MethodsPatients received oral temozolomide on days 1 through 5 combined with oral irinotecan on days 1 through 5 and 8 through 12 in 3-week courses. Daily oral cefixime was used to reduce irinotecan-associated diarrhea.ResultsFourteen assessable patients received 75 courses. Because neutropenia and thrombocytopenia were initially dose-limiting, temozolomide was reduced from 100 to 75 mg/m2/d for subsequent patients. Irinotecan was then escalated from 30 to 60 mg/m2/d. First-course grade 3 diarrhea was dose-limiting in one of six patients treated at the irinotecan MTD of 60 mg/m2/d. Other toxicities were mild and reversible. The median SN-38 lactone area under the plasma concentration versus time curve at this dose was 72 ng · hr/mL. One patient with bulky soft tissue disease had a complete response through six courses. Six additional patients received a median of seven courses (range, three to 22 courses) before progression.ConclusionThis all-oral regimen was feasible and well tolerated in heavily pretreated children with resistant neuroblastoma, and seven (50%) of 14 assessable patients had response or disease stabilization for three or more courses in this phase I trial. SN-38 lactone exposures were similar to those reported with protracted intravenous irinotecan. The dosages recommended for further study in this patient population are temozolomide 75 mg/m2/d plus irinotecan 60 mg/m2/d when given with cefixime.

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Phase I Study of Combination Topotecan and Carboplatin in Pediatric Solid Tumors

Journal of Clinical Oncology ◽

10.1200/jco.2002.20.1.88 ◽

2002 ◽

Vol 20 (1) ◽

pp. 88-95 ◽

Cited By ~ 13

Author(s):

Uma H. Athale ◽

Clinton Stewart ◽

John F. Kuttesch ◽

Albert Moghrabi ◽

William Meyer ◽

...

Keyword(s):

Phase I ◽

Solid Tumors ◽

Area Under The Curve ◽

Systemic Exposure ◽

Complete Response ◽

Maximum Tolerated Dose ◽

Hematologic Toxicity ◽

Pediatric Solid Tumors ◽

Group A ◽

Group B

PURPOSE: We conducted a phase I trial of escalating doses of topotecan (TOPO) in association with a fixed systemic exposure of carboplatin (CARBO) with or without granulocyte colony-stimulating factor (G-CSF) in children. PATIENTS AND METHODS: Two separate cohorts of patients (pts) with solid tumors were studied: (A) pts with refractory or recurrent disease and (B) pts with no prior myelosuppressive therapy or newly diagnosed tumors for which there was no standard chemotherapy. CARBO was given on day 1 at an area under the curve of 6.5, followed by TOPO as a continuous infusion for 3 days; the starting dose of TOPO was 0.50 mg/m2/d. Cycles were repeated every 21 days. G-CSF was given at a dose of 5 μg/kg/d starting on day 4. RESULTS: Forty-eight of 51 pts were assessable for toxicity. In group A, dose-limiting myelosuppression persisted despite de-escalation of TOPO to 0.3 mg/m2/d and use of G-CSF. In group B, the maximum-tolerated dose of TOPO was 0.5 mg/m2/d for 3 days, and 0.6 mg/m2/d for 3 days with G-CSF. No significant nonhematologic toxicities were observed. Among 46 pts assessable for response, one had complete response, five had partial response, and 18 had stable disease. CONCLUSION: Although this combination possesses antineoplastic activity in pediatric solid tumors, hematologic toxicity precluded any meaningful TOPO dose escalation. The addition of G-CSF did not alter this. The potential for preservation of activity and diminution of toxicity with alternative sequences and schedules of administration (topoisomerase followed by alkylating or platinating agents) should be evaluated.

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Preliminary Results from a Phase I Study of Revlimid® (Lenalidomide) in Combination with Vidaza® (Azacitidine) in Patients with Advanced Myelodysplastic Syndromes (MDS).

Blood ◽

10.1182/blood.v110.11.1458.1458 ◽

2007 ◽

Vol 110 (11) ◽

pp. 1458-1458 ◽

Cited By ~ 2

Author(s):

Mikkael A. Sekeres ◽

Alan List ◽

David Cuthbertson ◽

Ronald Paquette ◽

Thomas Loughran ◽

...

Keyword(s):

Phase I ◽

Injection Site Reaction ◽

Complete Response ◽

Maximum Tolerated Dose ◽

Hematologic Toxicity ◽

Toxicity Data ◽

Erythroid Response ◽

Early Results ◽

Grade 3 ◽

Dose Levels

Abstract Background: Early MDS becomes more advanced as immature myeloid cells proliferate, angiogenesis increases, genetic lesions accumulate, and tumor suppressor genes become inactivated through hypermethylation. Progression to acute myeloid leukemia (AML) may be prevented by targeting these defects through combination therapy, using an immunomodulatory, anti-angiogenic agent, lenalidomide (LEN), and a hypomethylating drug, azacitidine (AZA). Methods: We conducted a multicenter, Phase I trial in patients (pts) with advanced MDS (IPSS score ≥1.5, or FAB or WHO classification with ≥5% myeloblasts) starting in 6/06, with results reported through 7/07. Pts were enrolled using a “3+3” design (See Table), and could not receive LEN or AZA previously. Cycles lasted 28 days, to a maximum of 7 cycles of therapy. The primary endpoint was to determine the maximum tolerated dose (MTD) and dose-limiting toxicities (DLTs, defined as Grade 3/4 non-hematologic toxicity or >50% neutrophil (ANC) or platelet (plt) drop without recovery by Day 56) of the combination. A secondary endpoint was response as defined by the Modified International Working Group. Dose Level AZA Schedule LEN Schedule 1 75 mg/m2 SC days 1–5 5 mg PO days 1–14 2 75 mg/m2 SC days 1–5 5 mg PO days 1–21 3 75 mg/m2 SC days 1–5 10 mg PO days 1–21 4 50 mg/m2 SC days 1–5, 8–12 5 mg PO days 1–14 5 50 mg/m2 SC days 1–5, 8–12 5 mg PO days 1–21 6 50 mg/m2 SC days 1–5, 8–12 10 mg PO days 1–21 Results: Seven patients have been enrolled, 6 are evaluable for toxicity data. Median age was 64 years (range 52–70), 1 pt was female, and median follow-up is 5.5 months (range 1.5–13). All pts had RAEB-2; IPSS scores were 1.5 (4), 2.0 (2), and 3.0 (1), with IPSS cytogenetic risk categories of poor (1), intermediate (1), and good (5). No pt had a del (5q) lesion. Median time from MDS diagnosis was 3.5 wks (range 2–106). No DLTs occurred in Dose Levels 1 or 2, and MTD has not yet been reached. Grade 1/2 non-hematologic toxicities (n=6) included fatigue (4), injection site reaction (6), rash (3), pruritis (3), constipation or diarrhea (6), dizziness (1), and mucositis (1). Grade 3/4 non-hematologic toxicities included febrile neutropenia (1). Median ANC drop was 16.4% and plt drop was 10.4%. Although one patient was delayed 1 week in starting cycle 2 for neutropenia, there were no dose-reductions for toxicities. Four pts are evaluable for response: 2 had a complete response, 1 an erythroid response, and 1 progressive disease. Conclusions: The combination of LEN and AZA is well-tolerated and early results suggest efficacy in advanced MDS. Responses and toxicity data from higher Dose Levels will be presented.

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Phase I/II study of carfilzomib plus melphalan-prednisone (CMP) in elderly patients with de novo multiple myeloma.

Journal of Clinical Oncology ◽

10.1200/jco.2012.30.15_suppl.8009 ◽

2012 ◽

Vol 30 (15_suppl) ◽

pp. 8009-8009 ◽

Cited By ~ 5

Author(s):

Brigitte Kolb ◽

Cyrille Hulin ◽

Denis Caillot ◽

Lotfi Benboubker ◽

Mourad Tiab ◽

...

Keyword(s):

Phase I ◽

De Novo ◽

Maximum Tolerated Dose ◽

Toxicity Assessment ◽

Hematologic Toxicity ◽

Effective Combination ◽

Nonhematologic Toxicity ◽

Level 3 ◽

Level 1 ◽

Grade 3

8009 Background: Melphalan-prednisone + thalidomide (MPT) or bortezomib (MPV) are approved in frontline MM patients (pts) >65 years. Both regimens demonstrated significant benefit over MP alone in terms of PFS and OS but this benefit could be hampered by the risk of peripheral neuropathy (PN). Carfilzomib (Cfz) is a novel proteasome inhibitor that has demonstrated promising activity and favorable toxicity profile, with low rates of PN. This phase I/II study was designed to determine the maximum tolerated dose (MTD) of CMP, to assess safety and evaluate efficacy of this combination in newly diagnosed MM >65. Methods: In Phase I, Cfz was the only escalating agent starting at 20 mg/m2 (level 1) with maximal planned dose 36 mg/m2 (level 3), given IV on days 1, 2, 8, 9, 22, 23, 29, 30 for nine 42-day cycles. Oral melphalan 9 mg/m² and prednisone 60mg/m² were given on days 1 to 4, for all dose levels. Based on toxicity assessment, the study was amended to add dose level 4 (Cfz 45 mg/m2). MTD determination was based on occurrence of Dose limiting toxicities (DLTs) during the first cycle only. DLTs were defined as any grade 4 hematologic toxicity or preventing administration of 2 or more of the 8 Cfz doses of the first treatment cycle except grade 4 thrombocytopenia without bleeding or grade 4 neutropenia lasting ≤ 7 days; or grade ≥ 3 febrile neutropenia; or any other grade ≥ 3 nonhematologic toxicity. Results: As of January 20th 2012, 24 pts have been enrolled in the phase I: 6 pts at level 1 (Cfz 20), 6 at level 2 (Cfz 27), 6 at level 3 (Cfz 36), and 6 at level 4 (Cfz 45). There were 2 DLTs at level 4 (fever and hypotension not related to sepsis) and the MTD was considered to be 36 mg/m². Then, 16 additional pts were included in the phase II at level 3. Overall, 40 pts have been enrolled into the phase I/II study and 26 pts are evaluable for response. The ORR was 92% including 42% at least VGPR. These results compare favorably to those achieved with MPV, MPT, MPR or lenalidomide-dex (ORR 71, 76, 80 and 85%, respectively) in the same population. Conclusions: Frontline carfilzomib (36 mg/m2) + MP is a tolerable and very effective combination in elderly MM pts. Treatment is ongoing, with updated toxicity and efficacy data to be presented at the meeting.

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Plasma pharmacokinetics and pharmacodynamics of a new prodrug N-l-leucyldoxorubicin and its metabolites in a phase I clinical trial.

Journal of Clinical Oncology ◽

10.1200/jco.1992.10.12.1897 ◽

1992 ◽

Vol 10 (12) ◽

pp. 1897-1906 ◽

Cited By ~ 22

Author(s):

J de Jong ◽

G J Geijssen ◽

C N Munniksma ◽

J B Vermorken ◽

W J van der Vijgh

Keyword(s):

Clinical Trial ◽

Phase I ◽

Half Life ◽

Maximum Tolerated Dose ◽

Phase I Clinical Trial ◽

Major Constituent ◽

Hematologic Toxicity ◽

Time Curve ◽

Elimination Half Life ◽

Elimination Half

PURPOSE N-l-leucyldoxorubicin (Leu-Dox) was developed as a prodrug of doxorubicin (Dox) to circumvent the cardiotoxicity associated with repeated administration of Dox. Our purpose was to assess the pharmacokinetics of Leu-Dox, Dox, doxorubicinol (Dol) and four other metabolites for pharmacokinetically guided dose-escalation and to verify the prodrug character of Leu-Dox. PATIENTS AND METHODS Blood and urine of 14 patients were sampled during the phase I clinical trial and analyzed by high-performance liquid chromatography. Dose levels of Leu-Dox ranged from 18 mg/m2 to 225 mg/m2, the maximum-tolerated dose (MTD). Hematologic parameters were monitored regularly in each patient. RESULTS Leu-Dox was rapidly distributed (half-life at alpha phase [t1/2 alpha] = 2.5 +/- 0.6 minutes) followed by a biphasic elimination (half-life at beta phase [t1/2 beta] = 17.4 +/- 7.3 minutes; half-life at gamma phase [t1/2 gamma] = 1.5 +/- 0.5 hours), as measured over the first 12 hours after administration. In three patients, in whom Leu-Dox was found in the plasma for up to 48 hours after injection, a final elimination half-life (t1/2,elim) of 16 hours was observed. The t1/2,elim of Leu-Dox was short (0.6 to 16.5 hours) compared with the t1/2,elim of Dox (38 +/- 11 hours). The mean residence time and apparent volume of distribution were 23 +/- 5 minutes and 19 +/- 6 L/m2, respectively. Only 1.5% to 5% of the dose was excreted in the urine over 48 hours, with Dox as major constituent. Dox was rapidly formed, reaching its maximum concentration within 10 minutes after the end of Leu-Dox infusion. Areas under the plasma concentration versus time curve (AUC infinity, mean +/- SD, n = 16) of Leu-Dox, Dox, and Dol were 115 +/- 27 mumol.min/L, 41 +/- 12 mumol.min/L, and 33 +/- 14 mumol.min/L after a dose of 60 mg/m2 Leu-Dox (= 86 mumol/m2). After the same molar dose of Dox (50 mg/m2 = 86 mumol/m2), the AUC infinity of Dox was 179 mumol.min/L, indicating that Leu-Dox was converted into Dox for 23% in the plasma compartment. The AUCs infinity of Leu-Dox, Dox, and Dol increased linearly with the dose. Negligible AUCs were observed for the other four metabolites. The AUCs infinity of Leu-Dox and Dox at the MTD (517 and 145 mumol.min/L, respectively) were lower than those in mice at the LD10 (1,930 and 798 mumol.min/L, respectively), which means that the MTD could not be predicted from the preclinical pharmacokinetics in mice. Hematologic toxicity, especially the WBC count, appeared to correlate much better with the AUC of Dox (r = .91) than with the AUC of Leu-Dox (r = .74), thus confirming the prodrug character of Leu-Dox. CONCLUSIONS Dox is rapidly formed from Leu-Dox, and seems causative in the observed myelotoxicity. The MTD could not be predicted from the AUC at the LD10 in mice.

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