Shem Patyna

Sunitinib malate for the treatment of pancreatic neuroendocrine tumors

BACKGROUND The multitargeted tyrosine kinase inhibitor sunitinib has shown activity against pancreatic neuroendocrine tumors in preclinical models and phase 1 and 2 trials. METHODS We conducted a multinational, randomized, double-blind, placebo-controlled phase 3 trial of sunitinib in patients with advanced, well-differentiated pancreatic neuroendocrine tumors. All patients had Response Evaluation Criteria in Solid Tumors-defined disease progression documented within 12 months before baseline. A total of 171 patients were randomly assigned (in a 1:1 ratio) to receive best supportive care with either sunitinib at a dose of 37.5 mg per day or placebo. The primary end point was progression-free survival; secondary end points included the objective response rate, overall survival, and safety. RESULTS The study was discontinued early, after the independent data and safety monitoring committee observed more serious adverse events and deaths in the placebo group as well as a difference in progression-free survival favoring sunitinib. Median progression-free survival was 11.4 months in the sunitinib group as compared with 5.5 months in the placebo group (hazard ratio for progression or death, 0.42; 95% confidence interval [CI], 0.26 to 0.66; P<0.001). A Cox proportional-hazards analysis of progression-free survival according to baseline characteristics favored sunitinib in all subgroups studied. The objective response rate was 9.3% in the sunitinib group versus 0% in the placebo group. At the data cutoff point, 9 deaths were reported in the sunitinib group (10%) versus 21 deaths in the placebo group (25%) (hazard ratio for death, 0.41; 95% CI, 0.19 to 0.89; P=0.02). The most frequent adverse events in the sunitinib group were diarrhea, nausea, vomiting, asthenia, and fatigue. CONCLUSIONS Continuous daily administration of sunitinib at a dose of 37.5 mg improved progression-free survival, overall survival, and the objective response rate as compared with placebo among patients with advanced pancreatic neuroendocrine tumors. (Funded by Pfizer; ClinicalTrials.gov number, NCT00428597.).

Effect of the Multitargeted Tyrosine Kinase Inhibitors Imatinib, Dasatinib, Sunitinib, and Sorafenib on Mitochondrial Function in Isolated Rat Heart Mitochondria and H9c2 Cells

Cardiovascular disease has recently been suggested to be a significant complication of cancer treatment with several kinase inhibitors. In some cases, the mechanisms leading to cardiotoxicity are postulated to include mitochondrial dysfunction, either as a primary or secondary effect. Detecting direct effects on mitochondrial function, such as uncoupling of oxidative phosphorylation or inhibition of electron transport chain components, as well as identifying targets within the mitochondrial electron transport chain, can be accomplished in vitro. Here, we examined the effects of the tyrosine kinase inhibitor drugs imatinib, dasatinib, sunitinib, and sorafenib on ATP content in H9c2 cells grown under conditions where cells are either glycolytically or aerobically poised. Furthermore, we measured respiratory capacity of isolated rat heart mitochondria in the presence of the four kinase inhibitors and examined their effect on each of the oxidative phosphorylation complexes. Of the four kinase inhibitors examined, only sorafenib directly impaired mitochondrial function at clinically relevant concentrations, potentially contributing to the cytotoxic effect of the drug. For the other three kinase inhibitors lacking direct mitochondrial effects, altered kinase and other signaling pathways, are a more reasonable explanation for potential toxicity.

SU14813: a novel multiple receptor tyrosine kinase inhibitor with potent antiangiogenic and antitumor activity

Receptor tyrosine kinases (RTK), such as vascular endothelial growth factor receptor (VEGFR), platelet-derived growth factor receptor (PDGFR), stem cell factor receptor (KIT), and fms-like tyrosine kinase 3 (FLT3), are expressed in malignant tissues and act in concert, playing diverse and major roles in angiogenesis, tumor growth, and metastasis. With the exception of a few malignancies, seemingly driven by a single genetic mutation in a signaling protein, most tumors are the product of multiple mutations in multiple aberrant signaling pathways. Consequently, simultaneous targeted inhibition of multiple signaling pathways could be more effective than inhibiting a single pathway in cancer therapies. Such a multitargeted strategy has recently been validated in a number of preclinical and clinical studies using RTK inhibitors with broad target selectivity. SU14813, a small molecule identified from the same chemical library used to isolate sunitinib, has broad-spectrum RTK inhibitory activity through binding to and inhibition of VEGFR, PDGFR, KIT, and FLT3. In cellular assays, SU14813 inhibited ligand-dependent and ligand-independent proliferation, migration, and survival of endothelial cells and/or tumor cells expressing these targets. SU14813 inhibited VEGFR-2, PDGFR-β, and FLT3 phosphorylation in xenograft tumors in a dose- and time-dependent fashion. The plasma concentration required for in vivo target inhibition was estimated to be 100 to 200 ng/mL. Used as monotherapy, SU14813 exhibited broad and potent antitumor activity resulting in regression, growth arrest, or substantially reduced growth of various established xenografts derived from human or rat tumor cell lines. Treatment in combination with docetaxel significantly enhanced both the inhibition of primary tumor growth and the survival of the tumor-bearing mice compared with administration of either agent alone. In summary, SU14813 inhibited target RTK activity in vivo in association with reduction in angiogenesis, target RTK-mediated proliferation, and survival of tumor cells, leading to broad and potent antitumor efficacy. These data support the ongoing phase I clinical evaluation of SU14813 in advanced malignancies. [Mol Cancer Ther 2006;5(7):1774–82]

Electrocardiographic Characterization of the QTc Interval in Patients with Advanced Solid Tumors: Pharmacokinetic- Pharmacodynamic Evaluation of Sunitinib

Purpose: To evaluate the effects of sunitinib, a multitargeted tyrosine kinase inhibitor, on the QT interval in patients with cancer. Experimental Design: Patients received sunitinib loading doses (150-200 mg) on days 3 and 9 and maintenance doses (50 mg/d) on days 4 to 8. Moxifloxacin (day 1), placebo (day 2), and granisetron [with placebo (day 2) or sunitinib (days 3 and 9)] were also administered. Treatment effects were evaluated by time-matched, serial electrocardiograms, and manually overread. Results: Twenty-four of 48 patients were QT/PK evaluable. Moxifloxacin produced a time-matched, maximum mean placebo-adjusted corrected QT interval (QTcF) of 5.6 ms [90 confidence interval (CI), 1.9-9.3]. Sunitinib QTcF changes correlated with exposure, but not Tmax. Maximum mean time-matched, placebo-adjusted QTcF was 9.6 ms (90 CI, 4.1-15.1) at steady state/therapeutic concentrations (day 3) and 15.4 ms (90 CI, 8.4-22.4) at supratherapeutic concentrations (day 9). No patient had a QTcF >500 ms. Concomitant granisetron produced no significant QTcF prolongation. Sunitinib-related adverse events were as previously described. Conclusions: Sunitinib has a dose-dependent effect on QT interval. The increased risk of ventricular arrhythmias must be weighed against the therapeutic benefit sunitinib provides to patients with advanced cancer. (Clin Cancer Res 2009;15(22):704552)

Single- and multiple-dose disposition kinetics of sunitinib malate, a multitargeted receptor tyrosine kinase inhibitor: comparative plasma kinetics in non-clinical species.

PurposeThe purpose of these extensive non-clinical studies was to assess pharmacokinetics and dispositional properties of sunitinib and its primary active metabolite (SU12662).MethodsSunitinib was administered in single and repeat oral doses in mice, rats, and monkeys. Assessments were made using liquid-chromatography–tandem mass spectrometric methods, radioactive assays, and quantitative whole body autoradiography.ResultsSunitinib was readily absorbed with good oral bioavailability and linear kinetics at clinically-relevant doses. SU12662 plasma levels were less than those of sunitinib in mice and monkeys, but greater in rats. Sunitinib was extensively distributed with moderate-to-high systemic clearance and eliminated primarily into feces. Single- and repeat-dosing kinetics were similar. A prolonged half-life allowed once-daily dosing, enabling adequate systemic exposure with limited-to-moderate accumulation. In multiple-dose studies with cyclic dosing, drug plasma concentrations cleared from one cycle to the next.ConclusionsSunitinib exhibited advantageous pharmacokinetic and dispositional properties in non-clinical species, translating into favorable properties in humans.

Pharmacokinetics, Distribution, and Metabolism of [14C]sunitinib in Rats, Monkeys, and Humans

Sunitinib is an oral multitargeted tyrosine kinase inhibitor approved for the treatment of advanced renal cell carcinoma, imatinib-refractory gastrointestinal stromal tumor, and advanced pancreatic neuroendocrine tumors. The current studies were conducted to characterize the pharmacokinetics, distribution, and metabolism of sunitinib after intravenous and/or oral administrations of [14C]sunitinib in rats (5 mg/kg i.v., 15 mg/kg p.o.), monkeys (6 mg/kg p.o.), and humans (50 mg p.o.). After oral administration, plasma concentration of sunitinib and total radioactivity peaked from 3 to 8 h. Plasma terminal elimination half-lives of sunitinib were 8 h in rats, 17 h in monkeys, and 51 h in humans. The majority of radioactivity was excreted to the feces with a smaller fraction of radioactivity excreted to urine in all three species. The bioavailability in female rats was close to 100%, suggesting complete absorption of sunitinib. Whole-body autoradioluminography suggested radioactivity was distributed throughout rat tissues, with the majority of radioactivity cleared within 72 h. Radioactivity was eliminated more slowly from pigmented tissues. Sunitinib was extensively metabolized in all species. Many metabolites were detected both in urine and fecal extracts. The main metabolic pathways were N-de-ethylation and hydroxylation of indolylidene/dimethylpyrrole. N-Oxidation/hydroxylation/desaturation/deamination of N,N′-diethylamine and oxidative defluorination were the minor metabolic pathways. Des-ethyl metabolite M1 was the major circulating metabolite in all three species.

Evaluation of the safety and pharmacokinetics of the multi-targeted receptor tyrosine kinase inhibitor sunitinib during embryo–fetal development in rats and rabbits

BACKGROUND Angiogenesis plays a key role in embryo-fetal development and, based on nonclinical safety data, the majority of vascular endothelial growth factor (VEGF)-targeted antiangiogenic agents used in cancer therapy are not recommended during pregnancy. We investigated the effects of sunitinib (an oral inhibitor of multiple receptor tyrosine kinases [RTKs] including VEGF-receptors) on embryo-fetal development. METHODS Presumed-pregnant Sprague-Dawley rats and New Zealand White rabbits received repeated daily oral doses of sunitinib (0-30 mg/kg/day), during the major period of organogenesis. Clinical/physical examinations were performed throughout the gestation phase, and blood samples were collected to determine systemic exposure. Necropsy (including uterine examination) was performed on all animals and fetal morphology was examined. RESULTS The no-observed-adverse-effect level was 1-5 mg/kg/day for maternal toxicity and 3 mg/kg/day for developmental toxicity in rats; 1 and 0.5 mg/kg/day, respectively, in rabbits. Embryo-fetal toxicity included decreases in the number of live fetuses and increases in the numbers of resorptions and post-implantation/complete litter losses; these were observed at doses of > or =5 mg/kg/day in rats and 5 mg/kg/day in rabbits. Malformations included fetal skeletal malformations (generally thoracic/lumbar vertebral alterations) in rats and cleft lip/palate in rabbits. These developmental effects were observed at approximately 5.5- (rats) and approximately 0.3-times (rabbits) the human systemic exposure at the approved sunitinib dose (50 mg/day). CONCLUSIONS Similar effects have been reported with the prototype monoclonal antibody bevacizumab. As is typically observed for potent inhibitors of RTKs involved in angiogenesis, sunitinib was associated with embryo-fetal developmental toxicity in rats and rabbits at clinically relevant dose levels.

Phase II Study of Sunitinib in Patients with Non-small Cell Lung Cancer and Irradiated Brain Metastases

Introduction: Brain metastases frequently cause significant morbidity in patients with non-small cell lung cancer (NSCLC). Sunitinib is a multitargeted inhibitor of tyrosine kinase receptors, including vascular endothelial growth factor receptors and platelet-derived growth factor receptors, which has single-agent antitumor activity in refractory NSCLC. This phase II study evaluated the antitumor activity and safety of sunitinib in patients with pretreated NSCLC and irradiated brain metastases. Methods: Patients received sunitinib 37.5 mg on a continuous daily dosing schedule. The primary end point was progression-free survival. Secondary end points included overall survival, patient-reported outcomes, and safety, including risk of intracranial hemorrhage (ICH) associated with focal neurological deficit. Results: Sixty-four patients received sunitinib (median age 61 years), most (83%) had received prior systemic therapy, 63% had adenocarcinoma, and 19% had squamous cell carcinoma; most (55%) were never-smokers. Median progression-free survival was 9.4 weeks (90% confidence interval [CI]: 7.5–13.1), and median overall survival was 25.1 weeks (95% CI: 13.4–35.5). The most common treatment-emergent (all-causality) nonhematologic toxicities (any grade) were fatigue (38%) and decreased appetite and constipation (both 25%). The most common grade 3/4 nonhematologic toxicities were dyspnea (9%) and fatigue (8%). Lymphopenia (20%) and neutropenia (13%) were the most common grade 3/4 hematologic abnormalities. Serious neurologic adverse events occurred in six patients (9%), and none were treatment-related. No cases of ICH were reported. Conclusions: Sunitinib administration on a continuous daily dosing schedule in patients with NSCLC and brain metastases was safe and manageable, with no increased risk of ICH.

Reproductive Toxicity Assessment of Sunitinib, A Multitargeted Receptor Tyrosine Kinase Inhibitor, in Male and Female Rats

BACKGROUND Sunitinib (SUTENT, Pfizer Inc., New York, NY) is a multitargeted inhibitor of selected receptor tyrosine kinases, which produces an antiproliferative and antiangiogenic effect by blocking pathways fundamental to tumor growth and survival. We investigated the effects of sunitinib on male and female fertility and early embryonic development in the rat. METHODS In the female fertility and early embryonic development phase, untreated males were paired with treated females dosed at 0 (control), 0.5, 1.5, and 5 mg/kg/day from 14 days premating, through mating, to gestation day 7. In the male fertility phase, the same males were then treated 58 days at doses of 0 (control), 1, 3, and 10 mg/kg/day, mated with untreated females, with continued daily dosing for a total of 74 days. RESULTS There was no systemic toxicity- or treatment-related effects on fertility in female rats. Females exposed at 5 mg/kg/day had an increase in the number of early resorptions with associated decrease in viable embryos. In the males, body weight and food consumption were decreased at 10 mg/kg/day compared to the controls. Male reproductive capacity, as assessed by copulation, fertility, and conception indices, was not impacted at any dose level. Sperm morphology, concentration, and motility were also unaffected by treatment. CONCLUSIONS There were no effects on male reproduction. An increase in corpora lutea and an increase in early resorptions with associated reduction in viable embryos was noted in the females dosed 5 mg/kg/day. Sunitinib at doses up to 1.5 and 10 mg/kg/day had no effects on female and male reproduction, respectively.