Patricia Whitcomb

Phase I Trial and Pharmacokinetic Study of the Farnesyltransferase Inhibitor Tipifarnib in Children With Refractory Solid Tumors or Neurofibromatosis Type I and Plexiform Neurofibromas

PURPOSE This pediatric phase I trial of tipifarnib determined the maximum-tolerated dose (MTD), pharmacokinetics, and pharmacodynamics of tipifarnib in children with refractory solid tumors and neurofibromatosis type 1 (NF1) -related plexiform neurofibromas. PATIENTS AND METHODS Tipifarnib was administered twice daily for 21 days, repeated every 28 days starting at 150 mg/m2/dose (n = 4), with escalations to 200 (n = 12), 275 (n = 12), and 375 (n = 6) mg/m2/dose. The MTD was also evaluated on a chronic continuous dosing schedule (n = 6). Pharmacokinetic sampling was performed for 36 hours after the first dose and peripheral-blood mononuclear cells (PBMCs) were collected at baseline and steady state for determination of farnesyl protein transferase (FTase) activity and HDJ-2 farnesylation. RESULTS Twenty-three solid tumor and 17 NF1 patients were assessable for toxicity. The MTD was 200 mg/m2/dose, and dose-limiting toxicities on cycle 1 were myelosuppression, rash, nausea, vomiting, and diarrhea. The 200 mg/m2/dose was also tolerable on the continuous dosing schedule. Cumulative toxicity was not observed in the 17 NF1 patients who received a median of 10 cycles (range, 1 to 32 cycles). The plasma pharmacokinetics of tipifarnib were highly variable but not age dependent. At steady state on 200 mg/m2/dose, FTase activity was 30% compared with baseline, and farnesylation of HDJ-2 was inhibited in PBMCs. CONCLUSION Oral tipifarnib is well tolerated in children receiving the drug twice daily for 21 days and a continuous dosing schedule at 200 mg/m2/dose, which is equivalent to the MTD in adults. The pharmacokinetic profile of tipifarnib in children is similar to that in adults, and at the MTD, FTase is inhibited in PBMC in vivo.

Safety and pharmacokinetics of fluconazole in children with neoplastic diseases

To evaluate the safety, tolerance, and pharmacokinetics of fluconazole in children with neoplastic diseases, we studied fluconazole in 26 children, aged 5 to 15 years, with normal renal function who were receiving treatment for cancer. The patients received fluconazole, 2, 4, or 8 mg/kg per day for 7 days intravenously for a 2-hour period. Patients had no nausea or vomiting related to fluconazole; three patients had an asymptomatic rise in hepatic aminotransferase values after four to six doses (one patient at 2 mg/kg per day and two patients at 8 mg/kg per day), which returned to normal within 2 weeks after discontinuation of the drug. Fluconazole showed linear first-order kinetics over the dosage range tested and during multiple dosing. After the first dose, mean clearance was 22.8 +/- 2.3 ml/min, volume of distribution 0.87 +/- 0.06 L/kg, and terminal elimination half-life 16.8 +/- 1.1 hours. Similarly, after the last dose, clearance was 19.4 +/- 1.3 ml/min, volume of distribution 0.84 +/- 0.04 L/kg, and terminal elimination half-life 18.1 +/- 1.2 hours. Patients receiving their first fluconazole dose of 8 mg/kg achieved peak serum levels of 9.5 +/- 0.4 microgram/ml and trough levels of 2.7 +/- 0.5 microgram/ml 24 hours later, and an area under the serum concentration-time curve from time zero to infinity of 186 +/- 16 micrograms.hr per milliliter. Renal clearance of fluconazole was 65% +/- 5% of total clearance and demonstrated the predominantly renal excretion of this drug. We suggest that the shorter serum half-life and the higher frequency of aminotransferase elevations in comparison with those of adults warrant careful investigation of fluconazole in controlled clinical trials.

Successful treatment of hepatosplenic candidiasis through repeated cycles of chemotherapy and neutropenia

Background. Hepatosplenic candidiasis (HSC) or chronic disseminated candidiasis is an increasingly recognized problem in patients with cancer. Whether patients with HSC should continue to receive antineoplastic therapy, which may cause neutropenia with the risk for progressive HSC or breakthrough fungemia, can be a major dilemma. Patients with HSC at the National Cancer Institute continue antineoplastic therapy, when possible, during antifungal therapy for HSC, despite repeated bouts of neutropenia. Therefore, whether this strategy resulted in breakthrough fungemia or progression of HSC was investigated.

Vandetanib in Children and Adolescents with Multiple Endocrine Neoplasia Type 2B Associated Medullary Thyroid Carcinoma

Purpose: Medullary thyroid carcinoma (MTC) is a manifestation of multiple endocrine neoplasia type 2 (MEN2) syndromes caused by germline, activating mutations in the RET (REarranged during Transfection) proto-oncogene. Vandetanib, a VEGF and EGF receptor inhibitor, blocks RET tyrosine kinase activity and is active in adults with hereditary MTC. Experimental Design: We conducted a phase I/II trial of vandetanib for children (5–12 years) and adolescents (13–18 years) with MTC to define a recommended dose and assess antitumor activity. The starting dose was 100 mg/m2 administered orally, once daily, continuously for 28-day treatment cycles. The dose could be escalated to 150 mg/m2/d after two cycles. Radiographic response to vandetanib was quantified using RECIST (v1.0), biomarker response was measured by comparing posttreatment serum calcitonin and carcinoembryonic antigen (CEA) levels to baseline, and a patient-reported outcome was used to assess clinical benefit. Results: Sixteen patients with locally advanced or metastatic MTC received vandetanib for a median (range) 27 (2–52) cycles. Eleven patients remain on protocol therapy. Diarrhea was the primary dose-limiting toxicity. In subjects with M918T RET germline mutations (n = 15) the confirmed objective partial response rate was 47% (exact 95% confidence intervals, 21%–75%). Biomarker partial response was confirmed for calcitonin in 12 subjects and for CEA in 8 subjects. Conclusion: Using an innovative trial design and selecting patients based on target gene expression, we conclude that vandetanib 100 mg/m2/d is a well-tolerated and highly active new treatment for children and adolescents with MEN2B and locally advanced or metastatic MTC. Clin Cancer Res; 19(15); 4239–48. ©2013 AACR.

Diagnosis and therapeutic monitoring of invasive candidiasis by rapid enzymatic detection of serum d-arabinitol

BACKGROUND Using a rapid automated enzymatic assay, we prospectively investigated serum D-arabinitol (DA), a biochemical marker of invasive candidiasis, in a large population of high-risk patients to determine its potential diagnostic, therapeutic, and prognostic significance in invasive candidiasis. PATIENTS AND METHODS A total of 3,223 serum samples were collected from 274 patients with cancer. Serum DA concentrations were determined in coded serum samples analyzed by rapid enzymatic assay. Creatinine also was analyzed in the same system to determine a serum DA and creatinine ratio (DA/Cr). The sensitivity, specificity, correlation with therapeutic response, and prognostic significance were analyzed for all patient study groups. RESULTS A DA/Cr of > or = 4.0 mumol/L per mg/dL was detected in 31 (74%) of all 42 cases of fungemia and 25 (83%) of the 30 cases of the subset of persistent fungemia. Elevated DA/Cr was detected in 4 (40%) of 10 patients with tissue-proven, deeply invasive candidiasis and negative blood cultures (eg, hepatosplenic candidiasis or localized abscess) and 7 (44%) of 16 cases of deep mucosal candidiasis (eg, esophageal candidiasis). Elevated serial DA/Cr levels also were detected in persistently febrile and granulocytopenic patients requiring empirical amphotericin B. Among 26 assessable cases of fungemia, abnormally elevated DA/Cr values were detected in 14 (54%) before, 10 (38%) after, and 2 (8%) simultaneously with the first microbiologic report of fungemia. The trends of serial DA/Cr values correlated with therapeutic response in 29 (85%) of 34 patients with assessable cases of fungemia, decreasing in 8 (89%) of 9 patients with clearance of fungemia and increasing in 21 (84%) of 25 patients with persistence of fungemia. Among the 34 assessable patients with fungemia, mortality was directly related to the trend of serial DA/Cr determinations over time: 71% among fungemic patients who had persistently elevated or increasing DA/Cr, and 18% among the fungemic patients who had resolving DA/Cr or never had elevated DA/Cr (P < 0.01). CONCLUSIONS Rapid enzymatic detection of DA in serially collected serum samples from high-risk cancer patients permitted detection of invasive candidiasis, early recognition of fungemia, and therapeutic monitoring in DA-positive cases. Serially collected serum DA determinations complement blood cultures for improving detection and monitoring therapeutic response in patients at risk for invasive candidiasis.

Activity of Selumetinib in Neurofibromatosis Type 1–Related Plexiform Neurofibromas

BACKGROUND Effective medical therapies are lacking for the treatment of neurofibromatosis type 1-related plexiform neurofibromas, which are characterized by elevated RAS-mitogen-activated protein kinase (MAPK) signaling. METHODS We conducted a phase 1 trial of selumetinib (AZD6244 or ARRY-142886), an oral selective inhibitor of MAPK kinase (MEK) 1 and 2, in children who had neurofibromatosis type 1 and inoperable plexiform neurofibromas to determine the maximum tolerated dose and to evaluate plasma pharmacokinetics. Selumetinib was administered twice daily at a dose of 20 to 30 mg per square meter of body-surface area on a continuous dosing schedule (in 28-day cycles). We also tested selumetinib using a mouse model of neurofibromatosis type 1-related neurofibroma. Response to treatment (i.e., an increase or decrease from baseline in the volume of plexiform neurofibromas) was monitored by using volumetric magnetic resonance imaging analysis to measure the change in size of the plexiform neurofibroma. RESULTS A total of 24 children (median age, 10.9 years; range, 3.0 to 18.5) with a median tumor volume of 1205 ml (range, 29 to 8744) received selumetinib. Patients were able to receive selumetinib on a long-term basis; the median number of cycles was 30 (range, 6 to 56). The maximum tolerated dose was 25 mg per square meter (approximately 60% of the recommended adult dose). The most common toxic effects associated with selumetinib included acneiform rash, gastrointestinal effects, and asymptomatic creatine kinase elevation. The results of pharmacokinetic evaluations of selumetinib among the children in this trial were similar to those published for adults. Treatment with selumetinib resulted in confirmed partial responses (tumor volume decreases from baseline of ≥20%) in 17 of the 24 children (71%) and decreases from baseline in neurofibroma volume in 12 of 18 mice (67%). Disease progression (tumor volume increase from baseline of ≥20%) has not been observed to date. Anecdotal evidence of decreases in tumor-related pain, disfigurement, and functional impairment was observed. CONCLUSIONS Our early-phase data suggested that children with neurofibromatosis type 1 and inoperable plexiform neurofibromas benefited from long-term dose-adjusted treatment with selumetinib without having excess toxic effects. (Funded by the National Institutes of Health and others; ClinicalTrials.gov number, NCT01362803 .).

Pharmacokinetically Guided Phase 1 Trial of the IGF-1 Receptor Antagonist RG1507 in Children with Recurrent or Refractory Solid Tumors

Purpose: This pediatric phase I study was designed to identify the doses of RG1507, a monoclonal antibody against the Type 1 Insulin-like Growth Factor Receptor (IGF1R), that achieves exposures equivalent to those achieved in adults at recommended doses. Experimental Design: Children with relapsed or refractory solid tumors were treated using the same doses and administration schedules of RG1507 (3 and 9 mg/kg/wk, and 16 mg/kg every 3 weeks [q3W]) as those studied in adults. Detailed pharmacokinetic (PK) sampling was performed after the first dose; selected peak and trough levels were subsequently obtained. Target exposures were ≥85% of mean areas under concentration x time curves (AUCs) in adults at doses of 9 mg/kg/wk and 16 mg/kg q3W. A maximum tolerated dose could be identified if dose-limiting toxicities (DLT) occurred. Results: Thirty-one evaluable patients aged 3–17 years were enrolled at 3 mg/kg/wk (n = 3), 9 mg/kg/wk (n = 18), or 16 mg/kg q3W (n = 10). There were no DLTs. At 9 mg/kg/wk the mean AUC0–7d (21,000 μg h/mL) exceeded the target (16,000 μg h/mL). At 16 mg/kg q3W, the mean AUC021d (70,000 μg h/mL) exceeded the target (59,400 μg h/mL). Clearance normalized to body weight was age dependent. There were no objective responses. Seven patients had stable disease for >12 weeks, including two patients with osteosarcoma with stable disease for 52+ and 78+ weeks. Conclusions: The recommended doses of RG1507 in children with solid tumors are 9 mg/kg/wk and 16 mg/kg q3W. This flexible design is well suited for trials of agents associated with limited toxicity. Clin Cancer Res; 17(3); 611–9. ©2010 AACR.

Vandetanib Successfully Controls Medullary Thyroid Cancer-Related Cushing Syndrome in an Adolescent Patient

CONTEXT Ectopic Cushing syndrome due to ACTH secretion from metastatic medullary thyroid cancer (MTC) is associated with significant morbidity and mortality. OBJECTIVE The aim of the study was to describe the first case of Cushing syndrome associated with MTC in a pediatric patient and the successful reversal of Cushing syndrome with tyrosine kinase inhibitor (vandetanib) therapy. PATIENT AND METHODS A 17-year-old Brazilian adolescent presented with metastatic MTC and associated ACTH-dependent ectopic Cushing syndrome in the context of multiple endocrine neoplasia type 2B. When the patient was treated with the tyrosine kinase inhibitor vandetanib, rapid decrease in serum cortisol and improvement of clinical symptoms were observed. CONCLUSION We describe the first pediatric case of clinical and biochemical improvement of paraneoplastic MTC-related Cushing syndrome after treatment with vandetanib. Vandetanib and possibly other tyrosine kinase inhibitors may be a novel beneficial option in patients with neuroendocrine tumor-related ectopic Cushing syndrome.

111In-Octreotide Scintigraphy for Identification of Metastatic Medullary Thyroid Carcinoma in Children and Adolescents

CONTEXT Most medullary thyroid cancers (MTC) express somatostatin receptors; therefore, (111)In-octreotide somatostatin receptor scintigraphy (SRS) may be useful in detecting sites of metastases in children with MTC. OBJECTIVE The aim of the study was to evaluate tumor metastases in children and adolescents with MTC using SRS in comparison to conventional imaging. DESIGN AND SETTING A case series was conducted as part of baseline evaluation for cancer treatment protocol at the National Institutes of Health Clinical Center. PATIENTS Eleven patients with a median age of 15 (range, 9-17) yr participated in the study, 10 with histologically proven, metastatic MTC due to the M918T mutation of the RET protooncogene, and one with a known RET polymorphism. INTERVENTION After receiving 0.086 mCi/kg (111)Indium-pentreotide, patients were examined with a single photon emission computed tomography scan 4 and 24 h after injection. Baseline conventional imaging, including computed tomography (neck, chest, abdomen, ± pelvis, adrenals), magnetic resonance imaging (neck), and bone scan, was performed on all patients. MAIN OUTCOME MEASURES SRS results were compared with conventional imaging. RESULTS Five of the 11 patients had abnormal findings on SRS. Of the 53 total target lesions present in the patients, only 24.5% were accurately identified through SRS. CONCLUSIONS SRS appears to be less sensitive than conventional imaging at detecting the full extent of metastatic disease in children and adolescents with hereditary MTC. SRS incompletely identified sites of tumor and failed to visualize small sites of tumor or liver and lung metastases, and it has a limited role in the evaluation of metastatic disease in pediatric MTC patients.

Pediatric Phase I Trial Design Using Maximum Target Inhibition as the Primary Endpoint

The extent to which a drug inhibits a target responsible for a therapeutic effect is a more rational primary endpoint for dose-finding studies of more selective anticancer drugs than the conventional endpoint of dose-limiting toxicity (DLT) used for cytotoxic agents. An adaptive phase I trial design incorporating maximum target inhibition as the primary endpoint was developed to define the optimal dose of talabostat, a dipeptidyl peptidase (DPP) inhibitor, in children with relapsed or refractory solid tumors. The relationship between dose and effect (percent inhibition of serum DPP-4) was assessed using a maximum effect model. Maximum target inhibition was defined as greater than 90% DPP-4 inhibition in five or more of six patients 24 hours post-dose. If DLT was to occur, the trial would adapt to a traditional phase I design with a more conservative dose escalation. At the 600 microg/m(2) dose level, serum DPP-4 inhibition at 24 hours was 85%. No talabostat-related DLT occurred. The maximum effect model predicted that 1200 microg/m(2) of talabostat would maximally inhibit DPP-4. This adaptive trial design appears to be feasible, safe, and efficient and warrants further evaluation for development of molecularly targeted agents.