CTNI-55. THE CDK4/6 INHIBITOR ABEMACICLIB IN PATIENTS WITH RECURRENT MENINGIOMA AND OTHER PRIMARY CNS TUMORS

BACKGROUND

Medical therapies for recurrent brain tumors are limited. Abemaciclib is a small molecule CDK4/6 inhibitor that has demonstrated antitumor activity in multiple cancer types and crosses the blood-brain barrier.

METHODS

We conducted a phase II trial of single-agent abemaciclib in patients with recurrent primary brain tumors utilizing a novel CNS basket trial design with multiple tumor types accrued to separate cohorts including patients with recurrent IDH-wildtype gliomas (Cohort A), any recurrent gliomas requiring cytoreductive surgery (Cohort B), and any other recurrent primary brain tumors (Cohort C) including IDH-mutant gliomas, meningiomas, and other tumor types. In all patients, abemaciclib was administered orally at 200mg twice daily for each 28-day cycle. In cohort B abemaciclib was administered 4-7 days prior to surgery then resumed after recovery. Neuroimaging disease assessments were performed every two cycles. Cohorts were individually assessed for efficacy, tumoral molecular characteristics, and exploratory biomarker analyses. Next generation sequencing was performed on patients who had prior surgery.

RESULTS

To date, a total of 61 patients have enrolled and initiated treatment with abemaciclib. Cohort A enrolled 9 patients with IDH-wildtype WHO grade II and III astrocytomas. Cohort B enrolled 10 patients with astrocytomas of varying IDH-status. Cohort C is a diverse group of 42 patients including 22 treatment-refractory meningiomas, 10 IDH-mutant gliomas (5 astrocytomas, 5 oligodendrogliomas), 3 ependymomas, 3 primary CNS lymphomas, 2 pituitary tumors, 1 glioneuronal rosette forming tumor, and 1 diffuse midline glioma. A total of 7 grade 3 toxicities occurred in 6 patients: fatigue (3), neutropenia (2), colitis (1) and seizure (1); no grade 4 toxicities occurred.

CONCLUSIONS

We present the results of a novel CNS basket trial looking at the efficacy of abemaciclib across multiple recurrent primary brain tumors. Efficacy results will be presented, highlighting an update on promising results in the 22 patients with recurrent meningiomas.

CTNI-61. PILOT STUDY OF REPEATED PLANNED GLUCARPIDASE FOLLOWING HIGH DOSE METHOTREXATE (HD-MTX) IN CNS LYMPHOMA (CNSL)

This study explores the repeated use of glucarpidase following HD-MTX in patients with CNSL. HD-MTX requires aggressive hydration and inpatient monitoring to prevent toxicity. Glucarpidase 50 units(u)/kg for delayed MTX clearance results in a reduction of systemic MTX levels without crossing the blood brain barrier. This study explores the use of 1000 or 2000 units of glucarpidase following repeated cycles of MTX 3–8 g/m2. Eligible adult patients had isolated CNSL, CrCl ≥ 60 mL/min, and KPS ≥ 50. Rituximab with MTX was administered for eight cycles. Glucarpidase was given 24 hours after each MTX infusion. MTX concentrations were monitored in serum and cerebrospinal fluid (CSF). Twelve patients enrolled to date and data are available for 50 doses of MTX (3 g/m2 (20), 6 g/m2 (21), 8 g/m2 (9)). Glucarpidase 1000u (14) or 2000u (36) resulted in at least a 95% reduction in serum MTX levels within 15 minutes following 49/50 doses. A 93% decrease was seen with the remaining dose. Glucarpidase was not detected in the CSF of 7 patients analyzed. Potentially cytotoxic MTX concentrations (10–6 M) were observed in CSF 1 hour (7/7) and 6 hours (4/7) after glucarpidase administration. Radiographic responses are evaluable in 9 patients: complete response (5), partial response (2), stable disease (1), and progressive disease (1). No grade 3 events were attributed to glucarpidase; one grade 4 event of anaphylaxis occurred. Anti-glucarpidase antibodies were detected in 2/5 patients analyzed. In summary, administration of low-dose glucarpidase 24 hours after MTX 3–8 g/m2 results in a reproducible rapid reduction in serum MTX levels in non-renally impaired patients. CSF MTX levels remain therapeutic and clinical response expected from MTX-based therapy does not appear compromised. Anti-glucarpidase antibodies may develop though significance remains unclear. Study is ongoing. Future directions will explore glucarpidase use for reduction of inpatient stay with HD-MTX.

QOLP-19. A NEW MODEL OF CARE FOR PATIENTS WITH CENTRAL NERVOUS SYSTEM CANCERS

Patients (pts) with primary or metastatic central nervous system (CNS) cancers often have multiple physical, psychosocial, and spiritual needs. Neurological impairments can transform relationship dynamics with caregivers. These issues are difficult to address within a single outpatient oncology clinic. The Neurological Multidisciplinary Care Clinic (MdCC) at Memorial Sloan Kettering Cancer Center was a pilot study from 08/2017 to 04/2019 to foster a new model of care for complex pts with CNS cancers to identify and address their needs. The MdCC team: a neurologist, nurse, physiatrist (RM), physical therapist, social worker (SW), case manager (CM), dietitian (RD), and chaplain saw each pt/caregiver during a 3-hour visit. Since 11/2017 participants completed validated surveys on unmet needs, financial strain, and home equipment prior to their visit and satisfaction surveys afterward. Descriptive statistics were used to analyze results. Seventy-eight pts were seen: 39 were female, median age 59. Of these 78 pts, 65 had primary CNS cancers; predominantly glioblastoma (52%) and high-grade glioma (29%). Over 60% had never seen a SW, CM, RD, or physiatrist prior to MdCC. Seventy-six pts (97%) received symptom management recommendations. Prognosis/coping with cancer was discussed with 72 (92%) which increased signed health care proxy forms by 17% and DNR orders by 6% at time or within a month post MdCC. New/updated physical therapy was ordered for 48 pts (61%), orthotics for 8 (10%), and new equipment for 12 (15%). 25 pts (32%) continued following with physiatrists. Forty-eight pts completed a satisfaction survey; of these, 96% were highly satisfied, and would recommend MdCC to others. Pts’/caregivers’ unmet needs were effectively identified and addressed in this new model, The presence of these providers at time of MdCC allows for real time assessment of pts’/caregivers’, their support system, multidisciplinary team collaboration, planning, coordination of community services and implementation of a safe patient centered plan of care.

RARE-42. INCIDENCE AND BEHAVIOR OF CENTRAL NERVOUS SYSTEM INVOLVEMENT IN PATIENTS WITH HODGKIN’S LYMPHOMA

INTRODUCTION

Central nervous system (CNS) involvement from Hodgkin’s Lymphoma (HL) is rare, with a reported incidence of 0.07–0.5%. There is a paucity of data regarding its natural history and management.

METHODS

In this retrospective single-institution review, we analyzed all adult patients with HL for CNS involvement (parenchymal or meningeal), who were evaluated at Memorial Sloan Kettering Cancer Center from January 2008 until December 2018.

RESULTS

A total of 3478 patients with HL were identified, and CNS involvement was found in 10 patients (0.3%). All patients were symptomatic from CNS disease. Four patients had a synchronous presentation. The other 6 patients had a median time from systemic diagnosis to CNS involvement of 8 years (2.5–14). Two patients had radiographic evidence of leptomeningeal disease, however 4 had positive cerebrospinal fluid (CSF) cytology. At time of CNS involvement, 2 patients had confirmed transformation to Non-Hodgkin-Lymphoma on biopsy. 2 patients had EBV-positive HL. One patient died before treatment. Five patients received high-dose methotrexate (HD-MTX) for CNS disease. Of these patients, 1 died during treatment, 2 had partial responses, and 2 had complete response of both systemic and CNS disease; to date they are in remission. Three patients had varied responses to immunotherapy and cytotoxic chemotherapy. Removal of an immunosuppressive agent resolved disease in one EBV-positive patient. Median overall survival (OS) from diagnosis of HL was 10.6 years (1.1–21.2), and OS from time to CNS involvement was 6 years (0.2–15).

CONCLUSION

The median time from diagnosis to CNS involvement, and OS from time of CNS involvement are higher than previously reported, which may be related to newer therapies for systemic disease. Neuroimaging should be used in conjunction with CSF for diagnostic accuracy. HD-MTX can be used to treat CNS and refractory systemic disease, as historically used for the latter.

PATH-33. GERMLINE PREDICTORS OF HEMATOLOGIC TOXICITY IN PATIENTS WITH GLIOMA TREATED WITH CHEMOTHERAPY

BACKGROUND

Temozolomide is an alkylating agent commonly used in treatment of gliomas. While this agent is generally well-tolerated, hematologic toxicity is a known complication with grade 3/4 thrombocytopenia in 4% and grade 3/4 neutropenia in 8% of adults. Recent data in several non-CNS malignancies suggested that patients with germline mutations may carry an increased risk of hematological toxicity in the setting of alkylator chemotherapy. We aimed to investigate if germline mutations in glioma patients are associated with myelotoxicity during alkylating chemotherapy.

METHODS

In this retrospective single-institution study, we reviewed patients with glioma treated at Memorial Sloan Kettering Cancer Center (MSKCC) who had confirmed germline mutations identified by the institution’s Integrated Mutation Profiling of Actionable Cancer Targets (MSK-IMPACT) testing. MSK-IMPACT evaluates DNA for mutations in 76 genes known to be associated with hereditary cancer predisposition.

RESULTS

In 283 patients with glioma who underwent MSK-IMPACT testing, 16 distinct germline mutations were identified in 40 (14%) individuals. 27 had high-grade and 13 had low-grade glioma. Median age was 47 (range 1–79), 12 patients were women. 30 patients received temozolomide chemotherapy. Of the patients treated, four (13%) developed severe hematologic toxicity. Two cases of grade 3 neutropenia and four cases of grade 3/4 thrombocytopenia were identified. Temozolomide was stopped during radiation therapy for three patients with grade 4 thrombocytopenia or neutropenia, and dose-reduced in one patient with grade 3 thrombocytopenia. In patients who had hematologic toxicity, germline mutations were identified in genes NBN, ATM, EPCAM, and FANCC. NBN, ATM, and FANCC are involved in DNA repair. EPCAM is involved in cell adhesion.

CONCLUSIONS

Hematologic toxicity is a known complication with alkylator chemotherapy. Germline testing may identify patients at increased risk, leading to closer monitoring, modified dosing regimens to minimize myelosuppression, and quicker intervention to prevent interruptions in treatment.

Abstract B39: A pilot study of neuropsychological functions, APOE, and amyloid imaging in patients with gliomas

Patients with brain tumors treated with radiotherapy (RT) often develop cognitive dysfunction, and recent studies suggest that the apolipoprotein (APOE) ε-4 allele may influence cognitive outcome. The ε-4 allele promotes beta (β) amyloid deposition in the cortex, and preliminary evidence suggests that RT may be associated with β-amyloid deposition. In this pilot study, we assessed neuropsychological functions and β-amyloid retention using 18F-florbetaben PET in a subset of brain tumor patients who participated in our study of APOE polymorphisms and cognitive functions. Twenty glioma patients treated with conformal RT ± chemotherapy participated in the study: 6 were APOE ε-4 carriers and 14 were non-ε-4 carriers. Patients completed a neuropsychological reevaluation and brain MRI and 18F-florbetaben PET scans. The results of Wilcoxon rank sums test comparisons between prior and current assessments showed a significant decline in selective attention (Brief Test of Attention, p=0.018), and a near-significant decline in verbal learning (Hopkins Verbal Learning Test-Learning, p=0.07). Comparisons between assessments by APOE status showed a significant decline in attention and working memory (WAIS-III digits forward, p=0.028 and digits backward, p=0.032) among APOE ε-4 carriers. Comparisons of PET regional standard uptake value ratios (SUVRs) showed near-significant differences for the medial temporal cortex (p=0.069) and the putamen (p=0.069), with non-ε-4 carriers having higher SUVRs. The findings suggest that glioma patients may experience progressive worsening in attention and executive functions several years after treatment with RT ± chemotherapy, and that the APOE ε-4 allele may moderate cognitive decline.

Note: This abstract was not presented at the conference.

Citation Format: Denise Correa, Maria Kryza-Lacombe, Xiaosun Zhou, Raymond Baser, Brad Beattie, Zodina Beiene, Irene Orlow, John Humm, Lisa DeAngelis, Wolfgang Weber, Joseph Osborne. A pilot study of neuropsychological functions, APOE, and amyloid imaging in patients with gliomas [abstract]. In: Proceedings of the Tenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2017 Sep 25-28; Atlanta, GA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2018;27(7 Suppl):Abstract nr B39.

Multicenter, Phase 1, Dose Escalation Study of Hypofractionated Stereotactic Radiation Therapy With Bevacizumab for Recurrent Glioblastoma and Anaplastic Astrocytoma

PURPOSE

To establish the maximum tolerated dose of a 3-fraction hypofractionated stereotactic reirradiation schedule when delivered with concomitant bevacizumab to treat recurrent high-grade gliomas.

METHODS AND MATERIALS

Patients with recurrent high-grade glioma with Karnofsky performance status ≥60, history of standard fractionated initial radiation, tumor volume at recurrence ≤40 cm³, and absence of brainstem or corpus callosum involvement were eligible. A standard 3+3 phase 1 dose escalation trial design was utilized, with dose-limiting toxicities defined as any grade 3 to 5 toxicities possibly, probably, or definitely related to radiation. Bevacizumab was given at a dose of 10 mg/kg every 2 weeks. Hypofractionated stereotactic reirradiation was initiated after 2 bevacizumab doses, delivered in 3 fractions every other day, starting at 9 Gy per fraction.

RESULTS

A total of 3 patients were enrolled at the 9 Gy × 3 dose level cohort, 5 in the 10 Gy × 3 cohort, and 7 in the 11 Gy × 3 cohort. One dose-limiting toxicity of grade 3 fatigue and cognitive deterioration possibly related to hypofractionated stereotactic reirradiation was observed in the 11 Gy × 3 cohort, and this dose was declared the maximum tolerated dose in combination with bevacizumab. Although no symptomatic radionecrosis was observed, substantial treatment-related effects and necrosis were observed in resected specimens. The intent-to-treat median overall survival was 13 months.

CONCLUSIONS

Reirradiation using a 3-fraction schedule with bevacizumab support is feasible and reasonably well tolerated. Dose-escalation was possible up to 11 Gy × 3, which achieves a near doubling in the delivered biological equivalent dose to normal brain, in comparison with our previous 6 Gy × 5 schedule. Promising overall survival warrants further investigation.

Molecular and Clinical Effects of Notch Inhibition in Glioma Patients: A Phase 0/I Trial

PURPOSE

High-grade gliomas are associated with a dismal prognosis. Notch inhibition via the gamma-secretase inhibitor RO4929097 has emerged as a potential therapeutic option based on modulation of the cancer-initiating cell (CIS) population and a presumed antiangiogenic role.

EXPERIMENTAL DESIGN

In this phase 0/I trial, 21 patients with newly diagnosed glioblastoma or anaplastic astrocytoma received RO4929097 combined with temozolomide and radiotherapy. In addition to establishing the MTD, the study design enabled exploratory studies evaluating tumor and brain drug penetration and neuroimaging parameters. We also determined functional effects on the Notch pathway and targeting of CISs through analysis of tumor tissue sampled from areas with and without blood-brain barrier disruption. Finally, recurrent tumors were also sampled and assessed for Notch pathway responses while on treatment.

RESULTS

Treatment was well tolerated and no dose-limiting toxicities were observed. IHC of treated tumors showed a significant decrease in proliferation and in the expression of the Notch intracellular domain (NICD) by tumor cells and blood vessels. Patient-specific organotypic tumor explants cultures revealed a specific decrease in the CD133⁺ CIS population upon treatment. Perfusion MRI demonstrated a significant decrease in relative plasma volume after drug exposure. Gene expression data in recurrent tumors suggested low Notch signaling activity, the upregulation of key mesenchymal genes, and an increase in VEGF-dependent angiogenic factors.

CONCLUSIONS

The addition of RO4929097 to temozolomide and radiotherapy was well tolerated; the drug has a variable blood-brain barrier penetration. Evidence of target modulation was observed, but recurrence occurred, associated with alterations in angiogenesis signaling pathways. Clin Cancer Res; 22(19); 4786-96. ©2016 AACR.

Primary CNS lymphoma: is there a role for prophylaxis against lymphomatous meningitis?

This part of the program extends the previous discussion of metastatic CNS disease to prophylaxis of primary CNS lymphoma against meningeal involvement.

Myeloid biomarkers associated with glioblastoma response to anti-VEGF therapy with aflibercept

PURPOSE

VEGF and infiltrating myeloid cells are known regulators of tumor angiogenesis and vascular permeability in glioblastoma. We investigated potential blood-based markers associated with radiographic changes to aflibercept, which binds VEGF and placental growth factor (PlGF) in patients with recurrent glioblastoma.

EXPERIMENTAL DESIGN

In this single-arm phase II trial, aflibercept was given intravenously every two weeks until disease progression. Plasma and peripheral blood mononuclear cells were collected at baseline and 24 hours, 14 days, and 28 days posttreatment. Plasma cytokines and angiogenic factors were quantified by using ELISA and multiplex bead assays, and myeloid cells were assessed by flow cytometry in a subset of patients.

RESULTS

Circulating levels of VEGF significantly decreased 24 hours after treatment with aflibercept, coincident with radiographic response observed by MRI. PlGF initially decreased 24 hours posttreatment but increased significantly by days 14 and 28. Lower baseline levels of PlGF, elevated baseline levels of CTACK/CCL27, MCP3/CCL7, MIF, and IP-10/CXCL10, and a decrease in VEGFR1(+) monocytes from baseline to 24 hours were all associated with improved response. Tumor progression was associated with increases in circulating matrix metalloproteinase 9.

CONCLUSIONS

These data suggest that decreases in VEGF posttreatment are associated with radiographic response to aflibercept. Elevated baseline chemokines of monocyte lineage in responding patients supports a role for myeloid cells and chemokines as potential biomarkers and regulators of glioma angiogenesis.

Interaction between sorafenib and erlotinib

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Background: The combination of sorafenib plus erlotinib was evaluated in patients with recurrent glioblastoma (GBM). In addition to defining the maximum tolerated dose (MTD), pharmacokinetics (PKs) for single agent and combination were determined. Methods: Adults with recurrent GBM with the usual phase I inclusion/exclusion criteria were eligible. No enzyme inducing anti-epileptic agents were allowed. Starting doses for erlotinib and sorafenib were 100mg PO QD and 200 mg PO BID, respectively, for 28 days (a cycle). For cycle 1 PKs, erlotinib was started on day 1 followed on day 2 by sorafenib. Eight plasma samples were collected over 24hrs on days 1, 15 and 28. Sorafenib and its metabolite (N-oxide) were analyzed by HPLC and erlotinib and OSI-420 by LC/MS. PK parameters were characterized by standard non-compartmental methods. Results: The MTD was sorafenib 200 mg PO BID and erlotinib 100 mg PO QD. The PKs for erlotinib (OSI) are displayed below. Conclusions: The PKs for sorafenib are in agreement with previous reports and not affected by the co-administration of erlotinib. However, there is an apparent affect of sorafenib on the PKs of erlotinib. The expected accumulation of erlotinib's Cmax and AUC at steady-state was not observed. This interaction results in at least a 2+ fold decrease in exposure to erlotinib and its active metabolite. The interaction does not appear to be the classical enzyme induction due to the rapidity of the onset/offset. This same phenomenon has been reported with the co-administration of sorafenib with gefitinib (Clin Cancer Res 13:2684,2007). Increasing the maximal velocity (Vmax) of CYP3A4, not the quantity of enzyme, is suggested as a testable hypothesis (J Pharmacol Exp Ther 290:1.1998). The clinical relevance of this interaction with regard to toxicity and efficacy warrants further evaluation.

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No significant financial relationships to disclose.

Patterns of care and outcomes in patients with intracranial hemangiopericytomas: The Memorial Sloan-Kettering Cancer Center (MSKCC) experience

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Background: Intracranial hemangiopericytomas are rare primary brain tumors with a tendency to metastasize. Available literature is restricted to small series of patients, and little is known regarding optimal clinical management and disease course, particularly in the targeted therapy era. Methods: Retrospective review of all patients with intracranial hemangiopericytoma seen at MSKCC from January 1, 1990 to December 31, 2008. Patients were included if histology was reviewed at MSKCC, and if clinical information was deemed sufficient for the analysis. Results: A total of 32 patients met inclusion criteria. The median age was 43 (range 24–68), median KPS was 80 (range 70–100), 17 were women. Disease was metastatic at presentation in only one patient. Initial treatment consisted of surgical resection in all patients (gross total resection: 14 patients, partial resection: 7, equivocal/unknown extent of surgery: 11). Adjuvant radiotherapy following surgery was given to 21 patients. The median progression-free survival was 65 months; median overall survival was 153 months and the 15-year survival was 48%. Treatment for recurrence included re-resection in 19 patients, additional radiotherapy in 17, and chemotherapy in 10. Regimens used included cytotoxic chemotherapy (6 patients) and targeted therapy (sorafenib: 3 patients; sunitinib: 3; imatinib: 2; erlotinib: 1; sirolimus: 1; bevacizumab: 1). Stable disease was the best observed response to these agents. Metastatic sites throughout disease course included lungs in 7 patients, bone in 10, liver in 3 and chest wall in 2. Immunohistochemistry and molecular analyses are ongoing and updated results will be presented. Conclusions: Hemangiopericytomas can be associated with late recurrences, even in patients completely resected and irradiated. Salvage treatment with surgery and radiotherapy seems effective, although the efficacy of chemotherapy remains to be determined. Given the slow growth rates, the meaning of stable disease while on chemotherapy is uncertain. Several patients in this series received agents targeting PDGFR or VGFR pathways, but such strategies need to be investigated further.

No significant financial relationships to disclose.

Pharmacokinetic and tumor distribution characteristics of temsirolimus in patients with recurrent malignant glioma

PURPOSE

To characterize the pharmacokinetics of temsirolimus and its major metabolite, sirolimus, in patients receiving enzyme-inducing antiepileptic drugs (EIAED) compared with patients receiving non-EIAEDs. An additional objective was to determine whether concentrations of temsirolimus or sirolimus were achieved in brain tumor tissue.

EXPERIMENTAL DESIGN

Patients with recurrent malignant gliomas not receiving EIAEDs initially received temsirolimus weekly at a dose of 250 mg i.v. The dose was subsequently reduced to 170 mg due to intolerable side effects. For patients taking EIAEDs, the starting dose of temsirolimus was 250 mg with standard dose escalation until the maximal tolerated dose was established. Ten whole blood samples were obtained over a period of 24 h after administration of temsirolimus for pharmacokinetic assessments. Patients eligible for cytoreductive surgery received temsirolimus before tumor resection. Whole blood and tumor tissue were obtained for analysis.

RESULTS

Significant differences in the pharmacokinetic variables for temsirolimus and sirolimus were observed between the two patient groups at a comparable dose level of 250 mg. For patients receiving EIAEDs, the systemic exposure to temsirolimus was lower by 1.5-fold. Likewise, peak concentrations and exposure to sirolimus were lower by 2-fold. Measurable concentrations of temsirolimus and sirolimus were observed in brain tumor specimens. The average tissue to whole blood ratio for temsirolimus was 1.43 and 0.84 for sirolimus.

CONCLUSIONS

Drugs that induce cytochrome P450 3A4, such as EIAEDs, significantly affect the pharmacokinetics of temsirolimus and its active metabolite, sirolimus. Total exposure to temsirolimus and sirolimus was lower in the EIAED group at the maximum tolerated dose of 250 mg compared with the non-EIAED group at the maximum tolerated dose of 170 mg. However, brain tumor tissue concentrations of temsirolimus and sirolimus were relatively comparable in both groups of patients at their respective dose levels. Correlative analyses of the tissue for the inhibition of the key regulators (p70S6 kinase and 4E-binding protein 1) of mammalian target of rapamycin are necessary to define the therapeutic significance of the altered exposure to temsirolimus.

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

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.