A phase 1 study of the irreversible FLT3 inhibitor FF-10101 in relapsed or refractory acute myeloid leukemia.

ABSTRACT: FLT3 tyrosine kinase inhibitors (TKIs) have clinical efficacy for patients with FLT3-mutated AML (acute myeloid leukemia), but their impact is limited by resistance in the setting of monotherapy and by tolerability problems when used in combination therapies. FF-10101 is a novel compound that covalently binds to a cysteine residue near the active site of FLT3, irreversibly inhibiting receptor signaling. It is effective against most FLT3 activating mutations, and, unlike other inhibitors, is minimally vulnerable to resistance induced by FLT3 ligand. We conducted a phase 1 dose escalation study of oral FF-10101 in patients with relapsed and/or refractory AML, the majority of whom harbored FLT3-activating mutations and/or had prior exposure to FLT3 inhibitors. Fifty-four participants enrolled in cohorts receiving doses ranging from 10 to 225 mg per day and 50 to 100 mg twice daily (BID). The dose limiting toxicities were diarrhea and QT prolongation. Among 40 response-evaluable participants, the composite complete response rate was 10%, and the overall response rate (including partial responses) was 12.5%, including patients who had progressed on gilteritinib. Overall, 56% of participants had prior exposure to FLT3 inhibitors. The recommended phase 2 dose was 75 mg BID. FF-10101 potentially represents a next-generation advance in the management of FLT3-mutated AML. This trial was registered at www.ClinicalTrials.gov as #NCT03194685.

A phase 1/2a safety, pharmacokinetics, and efficacy study of the novel nucleoside analog FF-10502-01 for the treatment of advanced solid tumors.

BACKGROUND: The nucleoside FF-10502-01, structurally similar to but with different biologic effects than gemcitabine, shows promising activity both alone and combined with cisplatin in preclinical gemcitabine-resistant tumor models. We conducted an open-label, single-arm, 3 + 3 first-in-human trial to explore the safety, tolerability, and antitumor activity of FF-10502-01 in patients with solid tumors. METHODS: Patients with inoperable metastatic tumors refractory to standard therapies were enrolled. Escalating intravenous FF-10502-01 doses (8-135 mg/m2 ) were administered weekly for 3 weeks in 28-day cycles until progressive disease or unacceptable toxicity was observed. Three expansion cohorts were subsequently evaluated. RESULTS: A phase 2 dose of 90 mg/m2 was determined after evaluating 40 patients. Dose-limiting toxicities included hypotension and nausea. Phase 2a enrolled patients with cholangiocarcinoma (36), gallbladder cancer (10), and pancreatic/other tumors (20). Common adverse events were grade 1-2 rash, pruritus, fever, and fatigue. Grade 3 or 4 hematologic toxicities were observed at low incidences, including thrombocytopenia (5.1%) and neutropenia (2%). Confirmed partial responses (PRs) occurred in five patients with gemcitabine-refractory tumors, including three with cholangiocarcinoma and one each with gallbladder and urothelial cancer. Median progression-free and overall survival rates in patients with cholangiocarcinoma were 24.7 and 39.1 weeks, respectively. Prolonged progression-free survival in patients with cholangiocarcinoma was associated with BAP1 and PBRM1 mutations. CONCLUSION: FF-10502-01 was well tolerated with manageable side effects and limited hematologic toxicity. Durable PRs and disease stabilizations were observed in heavily pretreated biliary tract patients who had received prior gemcitabine. FF-10502-01 is distinct from gemcitabine and may represent an effective therapy.

Phase I Study of P-cadherin-targeted Radioimmunotherapy with 90Y-FF-21101 Monoclonal Antibody in Solid Tumors.

PURPOSE: 90Y-FF-21101 is an Yttrium-90-conjugated, chimeric mAb that is highly specific for binding to human placental (P)-cadherin, a cell-to-cell adhesion molecule overexpressed and associated with cancer invasion and metastatic dissemination in many cancer types. We report the clinical activity of 90Y-FF-21101 in a first-in-human phase I study in patients with advanced solid tumors. PATIENTS AND METHODS: The safety and efficacy of 90Y-FF-21101 were evaluated in a phase I 3+3 dose-escalation study in patients with advanced solid tumors (n = 15) over a dose range of 5-25 mCi/m2. Dosimetry using 111In-FF-21101 was performed 1 week prior to assess radiation doses to critical organs. Patients who demonstrated clinical benefit received repeated 90Y-FF-21101 administration every 4 months. RESULTS: 111In-FF-21101 uptake was observed primarily in the spleen, kidneys, testes, lungs, and liver, with tumor uptake observed in the majority of patients. Organ dose estimates for all patients were below applicable limits. P-cadherin expression H-scores ranged from 0 to 242 with 40% of samples exhibiting scores ≥100. FF-21101 protein pharmacokinetics were linear with increasing antibody dose, and the mean half-life was 69.7 (±12.1) hours. Radioactivity clearance paralleled antibody clearance. A complete clinical response was observed in a patient with clear cell ovarian carcinoma, correlating with a high tumor P-cadherin expression. Stable disease was observed in a variety of other tumor types, without dose-limiting toxicity. CONCLUSIONS: The favorable safety profile and initial antitumor activity observed for 90Y-FF-21101 warrant further evaluation of this radioimmunotherapeutic (RIT) approach and provide initial clinical data supporting P-cadherin as a potential target for cancer treatment.

Results of a Phase 1/2a dose-escalation study of FF-10501-01, an IMPDH inhibitor, in patients with acute myeloid leukemia or myelodysplastic syndromes.

FF-10501-01 potently inhibits inosine-5-monophosphate dehydrogenase (IMPDH), inducing anti-proliferative and pro-apoptotic effects in acute myeloid leukemia (AML) human cell lines resistant to hypomethylating agents. In this Phase 1/2a study, Phase 1 enrolled 38 patients with relapsed/refractory AML (n = 28) or myelodysplastic syndromes (MDS/CMML, n = 10) to receive FF-10501 oral doses 50-500 mg/m2 BID for 14 or 21 days out of each 28-day cycle. Fifteen additional patients with HMA-resistant MDS/CMML (Phase 2a) were treated at 400 mg/m2 BID for 21 days. Most Phase 1 adverse events were disease-related and low-grade. 3 of 19 (16%) evaluable AML patients achieved partial remission (31, 7, and 5 months). 2 of 20 (10%) evaluable MDS/CMML patients (Phase 1 and 2a) attained marrow complete remission, one continuing treatment for 17 months. While FF-10501-01 demonstrated clinical activity and target inhibition in heavily pretreated patients with AML and MDS/CMML, increased mucositis events led to Phase 2a closure (ClinTrials.gov#NCT02193958).

Oncology Nurse Engagement: The Impact of a Management Education Program.

BACKGROUND: Previous studies have demonstrated that a predictor of nurse engagement is a supportive work environment. Organizations that promote employee engagement have higher retention rates compared to their counterparts. The role of the nurse manager is critical to nursing engagement, and the principles of nurse engagement are teachable. OBJECTIVES: The aim was to measure the impact of a nurse manager engagement education program on oncology nurse engagement. METHODS: The oncology nurses (n = 20) who report to the nurse managers (n = 3) completed a pre- and postintervention nurse engagement survey to assess the effectiveness of the nurse manager education program on engagement. Descriptive statistics were used to analyze the results. FINDINGS: The results of the postintervention nurse engagement survey demonstrate that merely teaching nurse managers the principles of engagement is not enough to engage nurses. Further strategies are needed to improve nurse engagement.

Reactive Oxygen Species Generation in Human Cells by a Novel Magnetic Resonance Imaging Contrast Agent.

The novel positive-contrast magnetic resonance imaging (MRI) marker C4 consists of an aqueous solution of cobalt chloride (CoCl2) complexed with the chelator N-acetylcysteine (NAC). We evaluated whether the presence of C4 or its components would produce reactive oxygen species (ROS, including hydroxyl, peroxyl, or other reactive oxygen species) in cultured cells. Human cancer or normal cells were incubated with 1% (w/v) CoCl2·6H2O or 2% NAC or a combination of both (1% CoCl2·6H2O : 2% NAC in an aqueous solution, abbreviated as Co : NAC) in the presence or absence of H2O2. Intracellular ROS levels were measured and quantified by change in relative fluorescence units. Student's t-tests were used. In all cell lines exposed to 1000 µM H2O2, the Co : NAC led to ≥94.7% suppression of ROS at 5 minutes and completely suppressed ROS at 60 and 90 minutes; NAC suppressed ROS by ≥76.6% at 5 minutes and by ≥94.5% at 90 minutes; and CoCl2·6H2O suppressed ROS by ≥37.2% at 30 minutes and by ≥48.6% at 90 minutes. These results demonstrate that neither Co : NAC nor its components generated ROS; rather, they suppressed ROS production in cultured cells, suggesting that C4 would not enhance ROS production in clinical use.

Toxicity Evaluation of a Novel Magnetic Resonance Imaging Marker, CoCl2-N-Acetylcysteine, in Rats.

C4 (cobalt dichloride-N-acetylcysteine [1% CoCl2:2% NAC]) is a novel magnetic resonance imaging contrast marker that facilitates visualization of implanted radioactive seeds in cancer brachytherapy. We evaluated the toxicity of C4. Rats were assigned to control (0% CoCl2:NAC), low-dose (0.1% CoCl2:2% NAC), reference-dose (C4), and high-dose (10% CoCl2:2% NAC) groups. Agent was injected into the left quadriceps femoris muscle of the rats. Endpoints were organ and body weights, hematology, and serum chemistry and histopathologic changes of tissues at 48 hours and 28 and 63 days after dosing. Student's t tests were used. No abnormalities in clinical signs, terminal body and organ weights, or hematologic and serum chemistry were noted, and no gross or histopathologic lesions of systemic tissue toxicity were found in any treatment group at any time point studied. At the site of injection, concentration-dependent acute responses were observed in all treatment groups at 48 hours after dosing and were recovered by 28 days. No myofiber degeneration or necrosis was observed at 28 or 63 days in any group. In conclusion, a single intramuscular dose of C4 produced no acute or chronic systemic toxicity or inflammation in rats, suggesting that C4 may be toxicologically safe for clinical use in cancer brachytherapy.

A biodistribution and toxicity study of cobalt dichloride-N-acetyl cysteine in an implantable MRI marker for prostate cancer treatment.

PURPOSE: C4, a cobalt dichloride-N-acetyl cysteine complex, is being developed as a positive-signal magnetic resonance imaging (MRI) marker to localize implanted radioactive seeds in prostate brachytherapy. We evaluated the toxicity and biodistribution of C4 in rats with the goal of simulating the systemic effects of potential leakage from C4 MRI markers within the prostate. METHODS AND MATERIALS: 9-µL doses (equivalent to leakage from 120 markers in a human) of control solution (0.9% sodium chloride), 1% (proposed for clinical use), and 10% C4 solution were injected into the prostates of male Sprague-Dawley rats via laparotomy. Organ toxicity and cobalt disposition in plasma, tissues, feces, and urine were evaluated. RESULTS: No C4-related morbidity or mortality was observed in the biodistribution arm (60 rats). Biodistribution was measurable after 10% C4 injection: cobalt was cleared rapidly from periprostatic tissue; mean concentrations in prostate were 163 µg/g and 268 µg/g at 5 and 30 minutes but were undetectable by 60 minutes. Expected dual renal-hepatic elimination was observed, with percentages of injected dose recovered in tissues of 39.0 ± 5.6% (liver), >11.8 ± 6.5% (prostate), and >5.3 ± 0.9% (kidney), with low plasma concentrations detected up to 1 hour (1.40 µg/mL at 5-60 minutes). Excretion in urine was 13.1 ± 4.6%, with 3.1 ± 0.54% recovered in feces by 24 hours. In the toxicity arm, 3 animals died in the control group and 1 each in the 1% and 10% groups from surgical or anesthesia-related complications; all others survived to scheduled termination at 14 days. No C4-related adverse clinical signs or organ toxicity were observed. CONCLUSION: C4-related toxicity was not observed at exposures at least 10-fold the exposure proposed for use in humans. These data demonstrating lack of systemic toxicity with dual routes of elimination in the event of in situ rupture suggest that C4 warrants further investigation as an MRI marker for prostate brachytherapy.

In vitro and in vivo neuroprotective activity of the cardiac glycoside oleandrin from Nerium oleander in brain slice-based stroke models.

The principal active constituent of the botanical drug candidate PBI-05204, a supercritical CO(2) extract of Nerium oleander, is the cardiac glycoside oleandrin. PBI-05204 shows potent anticancer activity and is currently in phase I clinical trial as a treatment for patients with solid tumors. We have previously shown that neriifolin, which is structurally related to oleandrin, provides robust neuroprotection in brain slice and whole animal models of ischemic injury. However, neriifolin itself is not a suitable drug development candidate and the FDA-approved cardiac glycoside digoxin does not cross the blood-brain barrier. We report here that both oleandrin as well as the full PBI-05204 extract can also provide significant neuroprotection to neural tissues damaged by oxygen and glucose deprivation as occurs in ischemic stroke. Critically, we show that the neuroprotective activity of PBI-05204 is maintained for several hours of delay of administration after oxygen and glucose deprivation treatment. We provide evidence that the neuroprotective activity of PBI-05204 is mediated through oleandrin and/or other cardiac glycoside constituents, but that additional, non-cardiac glycoside components of PBI-05204 may also contribute to the observed neuroprotective activity. Finally, we show directly that both oleandrin and the protective activity of PBI-05204 are blood brain barrier penetrant in a novel model for in vivo neuroprotection. Together, these findings suggest clinical potential for PBI-05204 in the treatment of ischemic stroke and prevention of associated neuronal death.

MER1, a novel organic arsenic derivative, has potent PML-RARalpha-independent cytotoxic activity against leukemia cells.

Arsenic trioxide (ATO) is an inorganic arsenic derivative that is highly effective against PML-RARalpha-positive leukemia but much less against other hematological malignancies. We synthesized an organic arsenic derivative (OAD), S-dimethylarsino-thiosuccinic acid (MER1), which offers a superior toxicity profile and comparable in vitro activity relative to ATO. In Swiss Webster mice, maximally-tolerated cumulative dose of MER1 when given i.v. for 5 days was 100 mg/kg/d. We demonstrated that MER1 induced apoptosis and dose- and time-dependent inhibition of survival and growth in a panel of myeloid leukemia cell lines. Unlike ATO, this activity was independent of PML-RARalpha status and was not associated with induction of myeloid maturation. In NB4 and HL60 cells, MER1 and ATO induced caspase activation and dissipation of mitochondrial transmembrane potential. At the same time, MER1 induced generation of reactive oxygen species (ROS) and cell cycle arrest in G2/M phase and proved to be more potent than ATO at inducing apoptosis. ROS generation and intracellular glutathione levels were key modulators of MER1-induced cytotoxicity as evidenced by abrogation of apoptosis in myeloid leukemia cell lines pretreated with the disulfide bond-reducing agent dithiothreitol or the radical scavenger N-acetyl-L-cysteine. Collectively, these data indicate that MER1 induces apoptosis in PML-RARalpha-positive and -negative myeloid leukemia cells by enhancing oxidative stress. This agent, therefore, combines low in vivo toxicity with formidable in vitro pro-apoptotic ROS-mediated activity, and may represent a novel OAD suitable for clinical development against a variety of hematological malignancies.

Phase II evaluation of intravenous vinorelbine (Navelbine) in recurrent or refractory pediatric malignancies: a Children's Oncology Group study.

BACKGROUND: A Phase II trial was developed to determine the efficacy and toxicity of intravenous vinorelbine, a semi-synthetic vinca alkaloid, in children, adolescent, and young adults with recurrent or refractory solid malignancies. PROCEDURES: Fifty patients were enrolled among three strata: soft tissue sarcomas [rhabdomyosarcoma (RMS), non-rhabdomyosarcoma, primitive neuroepithelial tumor] (20 patients); brain tumors [astrocytoma (4 patients), medulloblastoma (2 patients), other (16 patients)] (22 patients); neuroblastoma (8 patients). Vinorelbine was given weekly for 6 consecutive weeks during an 8-week interval. The response rate and toxicity profile was assessed. RESULTS: Among the first 35 patients treated at 33.75 mg/m(2)/dose, 25 experienced grades 3-4 neutropenia (75%). The dose was decreased to 30 mg/m(2)/dose in the remaining 15 patients. The median age was 10 years (range, 1-25). Four responses (one complete, three partial) occurred within the soft tissue sarcoma strata (all with RMS) and two occurred in the brain tumor group (medulloblastoma and astrocytoma). The most common toxicities were hematological and neurological. CONCLUSION: Vinorelbine at dose of 30 mg/m(2) can be safely administered to children with recurrent or refractory solid malignancies. The study design identified vinorelbine to be active in the sarcoma category, with a response rate of 36% (4/11) among RMS patients.

Autophagic cell death of human pancreatic tumor cells mediated by oleandrin, a lipid-soluble cardiac glycoside.

Lipid-soluble cardiac glycosides such as bufalin, oleandrin, and digitoxin have been suggested as potent agents that might be useful as anticancer agents. Past research with oleandrin, a principle cardiac glycoside in Nerium oleander L. (Apocynaceae), has been shown to induce cell death through induction of apoptosis. In PANC-1 cells, a human pancreatic cancer cell line, cell death occurs not through apoptosis but rather through autophagy. Oleandrin at low nanomolar concentrations potently inhibited cell proliferation associated with induction of a profound G(2)/M cell cycle arrest. Inhibition of cell cycle was not accompanied by any significant sub G1 accumulation of cells, suggesting a nonapoptotic mechanism. Oleandrin-treated cells exhibited time- and concentration-dependent staining with acridine orange, a lysosomal stain. Subcellular changes within PANC-1 cells included mitochondrial condensation and translocation to a perinuclear position accompanied by vacuoles. Use of a fluorescent oleandrin analog (BODIPY-oleandrin) revealed co-localization of the drug within cell mitochondria. Damaged mitochondria were found within autophagosome structures. Formation of autophagosomes was confirmed through electron microscopy and detection of green fluorescent protein-labeled light chain 3 association with autophagosome membranes. Also observed was a drug-mediated inhibition of pAkt formation and up-regulation of pERK. Transfection of Akt into PANC-1 cells or inhibition of pERK activation by MAPK inhibitor abrogated oleandrin-mediated inhibition of cell growth, suggesting that the reduction of pAkt and increased pERK are important to oleandrin's ability to inhibit tumor cell proliferation. The data provide insight into the mechanisms and role of a potent, lipid-soluble cardiac glycoside (oleandrin) in control of human pancreatic cancer proliferation.

Acquired resistance to erlotinib in A-431 epidermoid cancer cells requires down-regulation of MMAC1/PTEN and up-regulation of phosphorylated Akt.

Erlotinib (Tarceva), an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, has clinical activity in advanced lung cancer, but disease that initially responds to erlotinib eventually progresses. The mechanism of this acquired resistance is unclear. We established two erlotinib-resistant pools of A-431 cells, a well-characterized epidermoid cancer cell line that constitutively overexpresses EGFR and is sensitive to erlotinib, by continuous exposure to erlotinib over a 6-month period. The extent of EGFR gene amplification or mutation of the EGFR tyrosine kinase domain was not altered in the resistant cells. Intracellular erlotinib concentrations, determined by liquid chromatography-tandem mass spectrometry, were almost the same in all three cell lines. Immunoprecipitation with EGFR antibody followed by detection with phosphotyrosine antibody revealed that erlotinib effectively reduced EGFR phosphorylation in both parental cells and resistant cells. Erlotinib induced mutated in multiple advanced cancers 1/phosphatase and tensin homologue (MMAC1/PTEN) and suppressed phosphorylated Akt (Ser(473)) but not in the erlotinib-resistant cells. Overexpression of MMAC1/PTEN by transfection with Ad.MMAC1/PTEN or by pharmacologic suppression of Akt activity restored erlotinib sensitivity in both resistant pools. Further, transfection of parental A-431 cells with constitutively active Akt was sufficient to cause resistance to erlotinib. We propose that acquired erlotinib resistance associated with MMAC1/PTEN down-regulation and Akt activation could be overcome by inhibitors of signaling through the phosphatidylinositol 3-kinase pathway.

Synthetic triterpenoid 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid induces growth arrest in HER2-overexpressing breast cancer cells.

HER2 overexpression is one of the most recognizable molecular alterations in breast tumors known to be associated with a poor prognosis. In the study described here, we explored the effect of HER2 overexpression on the sensitivity of breast cancer cells to the growth-inhibitory effects of 2-cyano-3,12-dioxooleana-1,9-dien-28-oic acid (CDDO), a synthetic triterpenoid, both in vitro and in vivo in a xenograft model of breast cancer. Both cell growth and colony formation in the soft agar assay, a hallmark of the transformation phenotype, were preferentially suppressed in HER2-overexpressing cell lines at low concentrations of CDDO, whereas growth-inhibitory effects at high concentrations did not correlate with the expression level of HER2. CDDO dose-dependently inhibited phosphorylation of HER2 in HER2-overexpressing cells and diminished HER2 kinase activity in vitro. CDDO induced the transactivation of the nuclear receptor peroxisome proliferator-activated receptor-gamma in both vector control and HER2-transfected MCF7 cells. Dose-response studies showed that the growth inhibition seen at lower concentrations of CDDO correlated with induction of the tumor suppressor gene caveolin-1, which is known to inhibit breast cancer cell growth. CDDO also reduced cyclin D1 mRNA and protein expression. In vivo studies with liposomally encapsulated CDDO showed complete abrogation of the growth of the highly tumorigenic MCF7/HER2 cells in a xenograft model of breast cancer. These findings provide the first in vitro and in vivo evidence that CDDO effectively inhibits HER2 tyrosine kinase activity and potently suppresses the growth of HER2-overexpressing breast cancer cells and suggest that CDDO has a therapeutic potential in advanced breast cancer.

Phase I evaluation of oral and intravenous vinorelbine in pediatric cancer patients: a report from the Children's Oncology Group.

PURPOSE: Vinorelbine (Navelbine) is an orally absorbable Vinca with broad antitumor activity. It differs from other Vinca in that it is structurally modified on the catharanthine nucleus and has differential actions on tubulin that render it less neurotoxic than other compounds in this class. We conducted a phase I study of vinorelbine given the activity of Vinca alkaloids in many pediatric tumors. EXPERIMENTAL DESIGN: We evaluated the safety and pharmacokinetics of oral and i.v. vinorelbine administered weekly x 6 in children (age, 2-17 years) with different tumors. Patients with disease involvement in the bone marrow were eligible but were stratified and dose-escalated separately. Oral vinorelbine (week 1) was administered as liquid-filled gelatin capsules at thrice the i.v. dose. Intravenous vinorelbine doses of 24 to 37.5 mg/m(2) were administered on weeks 2 to 6. RESULTS: The dose-limiting toxicity in patients without marrow involvement was reversible neutropenia. Common nonhematologic toxicities included < or = grade 2 nausea/vomiting and increased hepatic transaminases. A higher mean i.v. Cl(TB) was observed (1.75 +/- 1.0 L/h/kg) compared with adult reports, with a mean t(1/2B) of 16.5 +/- 9.7 hours. Mean oral bioavailability was 28.5 +/- 22.5%. The apparent oral clearance (12.1 +/- 13.0 L/h/kg) and volume of distribution (69.4 +/- 30.6 L/kg) were substantially higher than in adults given similar oral doses. CONCLUSIONS: The maximum tolerated dose in children without bone marrow involvement was 30 mg/m(2), similar to that reported in adults, with myelosuppression being the dose-limiting toxicity. Higher plasma clearance resulted in lower area under the plasma concentration-time curves at a given dose compared with that reported in adults.

Final results of a phase I and pharmacokinetic study of gamma-methylene-10-deazaaminopterin (MDAM) administered intravenously daily for five consecutive days in patients with solid tumors.

PURPOSE: To determine the maximum tolerated dose (MTD) of gamma-methylene-10-deazaaminopterin (MDAM), a unique antifolate structurally similar to methotrexate (MTX), in the treatment of patients with solid tumors and to characterize toxicity and pharmacokinetic profiles of MDAM administered intravenously for five consecutive days repeated every 21 days. METHODS: A group of 18 patients with treatment-refractory colorectal cancer (CRC) were given MDAM at increasing dose levels from 80 to 300 mg/m2 per day intravenously for 5 days every 3 weeks. RESULTS: A total of 18 patients were entered into the study. Grade 2 or less nausea, vomiting, diarrhea, anorexia and fatigue were observed at doses > or =160 mg/m2 per day. Both patients enrolled at 300 mg/m2 per day experienced grade 3 stomatitis and one patient had grade 4 granulocytopenia. At 270 mg/m2 per day, grade 3 stomatitis (n=2), thrombocytopenia (n=1) and hyperbilirubinemia (n=1) were observed. All toxicities were relatively brief in duration and reversible. Leucovorin rescue was not required. Of 17 evaluable patients, no complete or partial responses were observed, and 3 patients demonstrated stable disease. Pharmacokinetic analyses were performed in 16 of the 18 patients receiving MDAM at doses of 80, 160, 240, 270 and 300 mg/m2. Normalized clearance of MDAM was approximately 1.5 times that reported for MTX (125 vs 80 ml/min per m2) in adults. CONCLUSION: MDAM is a novel antifolate with potential pharmacokinetic and safety advantages over MTX. Based on the results of this phase I study, stomatitis emerged as the dose-limiting toxicity and the recommended starting dose for phase II trials using this schedule and route of administration is 240 mg/m2 per day.

Use of microdialysis to study platinum anticancer agent pharmacokinetics in preclinical models.

Microdialysis sampling of blood and extracellular fluid (ECF) of living tissue offers unique advantages for studying anticancer drug distribution, metabolism, and mechanisms of tumor drug resistance. We applied microdialysis sampling in a rat model to describe the pharmacokinetics of cisplatin and carboplatin simultaneously in blood and several peripheral tissues, including tumor tissue. After i.v. bolus drug administration, samples were collected every 10 min for 4-6 h using microdialysis probes implanted into the jugular vein, kidney, and either liver or subcutaneously growing breast tumor tissue in anesthetized Fisher 344 rats. Analyte concentrations are expressed as absolute extracellular concentrations obtained by correction of the data for in vivo recovery. For cisplatin, peak renal concentrations (mean, 36.7 and 80.1 micrograms/mL) always exceeded peak plasma (8.4 and 13.2 micrograms/mL) and hepatic (6.3 and 10.4 micrograms/mL) concentrations following 5 and 10 mg/kg doses, respectively. For carboplatin, doses of 20 and 30 mg/kg also resulted in high peak renal concentrations, which were similar at both dose levels (mean, 87.9 and 89.3 micrograms/mL). However, at 30 mg/kg peak hepatic carboplatin concentrations were increased significantly, resulting in a disproportionate 3.5-fold increase in mean AUC at the higher dose level. Tumor cisplatin and carboplatin AUCs were similar to that in the circulation, but variable, ranging from 52 to 109% of the corresponding plasma AUCs. Microdialysis was determined to be a reliable methodology for examining the in vivo disposition of platinum anticancer agents in multiple tissue types. Our results revealed expected large renal exposures following i.v. administration, and variable tumor exposure with dose. Significant increases in hepatic carboplatin exposure with increasing dose suggest a possible mechanism for high-dose carboplatin-induced hepatic toxicity.

Murine pharmacokinetics and metabolism of oleandrin, a cytotoxic component of Nerium oleander.

Pharmacokinetic studies of [3H]oleandrin, a cardiac glycoside component of Anvirzel, were conducted in mice after either an i.v. dose (40 micrograms/kg) or a p.o. dose (80 micrograms/kg). Oleandrin was rapidly absorbed after oral dosing (Cmax at 20 min) although the elimination half-life was longer (2.3 +/- 0.5 h) than that after i.v. dosing (0.4 +/- 0.1 h). The AUC0-infinity values obtained after i.v. and p.o. dosing were 24.6 +/- 11.1 and 14.4 +/- 4.3 (ng.h/ml), respectively, resulting in an oral bioavailability of approximately 30%. After i.v. administration, oleandrin concentration in liver was approximately twice that measured in heart or kidney tissue. Oleandrigenin, the aglycone of oleandrin, was also found in these tissues. At 5 min, > 60% of the total radioactivity in liver was due to oleandrin while 28% of the given dose was present as oleandrigenin. Twenty-four hours following injection, 8% of total radioactivity was excreted in urine and contained both oleandrigenin (4.4% of the injected dose) and oleandrin (1.9%). Sixty-six percent of injected radioactivity was found in feces and consisted of oleandrin and oleandrigenin in equal amounts. Uptake of oleandrin in brain after i.p. injection of oleandrin (3 mg/kg) or oleander extract (700 mg/kg) was examined. Measured by LC/MS/MS, oleandrin content in brain was higher following injection of extract than it was with an equivalent dose of oleandrin. The data suggest that components within oleander extract may enhance transport of oleandrin across the blood brain barrier.