Pharmacokinetics and Tolerability of the Novel Non-immunosuppressive Fingolimod Derivative, OSU-2S, in Dogs and Comparisons with Data in Mice and Rats.

In this study, we characterized the pharmacokinetics of OSU-2S, a fingolimod-derived, non-immunosuppressive phosphatase activator, in mice, rats, and dogs, as well as tolerability and food effects in dogs. Across all species tested, plasma protein binding for OSU-2S was > 99.5%, and metabolic stability and hepatic intrinsic clearance were in the moderate range. OSU-2S did not significantly modulate CYP enzyme activity up until 50 µM, and Caco-2 data suggested low permeability with active efflux at 2 µM. Apparent oral bioavailability in mice was 16% and 69% at 10 and 50 mg/kg, respectively. In rats, bioavailability was 24%, 35%, and 28% at 10, 30, and 100 mg/kg, respectively, while brain/plasma ratio was 36 at 6-h post-dose at 30 mg/kg. In dogs, OSU-2S was well tolerated with oral capsule bioavailability of 27.5%. Plasma OSU-2S exposures increased proportionally over a 2.5-20 mg/kg dose range. After 4 weeks of 3 times weekly, oral administration (20 mg/kg), plasma AUClast (26.1 µM*h), and Cmax (0.899 µM) were nearly 2-fold greater than those after 1 week of dosing, and no food effects were observed. The elimination half-life (29.7 h), clearance (22.9 mL/min/kg), and plasma concentrations of repeated oral doses support a 3-times weekly dosing schedule in dogs. No significant CBC, serum biochemical, or histopathological changes were observed. OSU-2S has favorable oral PK properties similar to fingolimod in rodents and dogs and is well tolerated in healthy animals. This work supports establishing trials of OSU-2S efficacy in dogs with spontaneous tumors to guide its clinical development as a cancer therapeutic for human patients.

Phase I Trial of Dabrafenib and Pazopanib in BRAF Mutated Advanced Malignancies.

PURPOSE: Several tumor types carry BRAF mutations and vascular endothelial growth factor pathway upregulation. Resistance mechanisms to BRAF inhibitors can include platelet-derived growth factor-ß upregulation. Dabrafenib, a BRAF inhibitor, and pazopanib, a multikinase inhibitor that targets vascular endothelial growth factor and platelet-derived growth factor, have not been combined previously. This phase I study was designed to evaluate the safety, pharmacokinetics, and pharmacodynamics of the combination. PATIENTS AND METHODS: Patients with any advanced BRAF mutated malignancy with adequate organ function were eligible. Prior use of dabrafenib or pazopanib was not allowed. Dosages started at dabrafenib 50 mg twice a day and pazopanib 400 mg daily on dose level (DL) 1, with maximum dosages of 150 mg twice a day and 800 mg daily on DL5. Pharmacokinetics and BRAF V600E plasma clone were measured, and efficacy was evaluated by imaging and tumor markers every 8 weeks. RESULTS: Twenty-three patients with 11 different tumor histologies were enrolled in five DLs. Two dose-limiting toxicities were observed-a grade 3 bowel perforation on DL3 and grade 3 arthralgia on DL5. Common drug-related adverse events included nausea (52%), skin papules (43%), diarrhea (39%), hand-foot syndrome (30%), anemia (26%), rash (22%), vomiting (22%), hypophosphatemia (22%), and transaminitis (22%). Five patients (22%) experienced a partial response, including low-grade ovarian serous carcinoma, thyroid cancer, and glioblastoma multiforme, and two patients (appendiceal and thyroid cancer) had stable disease > 6 months. Pharmacokinetic measurements revealed pazopanib levels < 17.5 µg/mL in 80% of treated patients at steady state, particularly at DL5. BRAF V600E plasma copies correlated with response and progression. CONCLUSION: Combination dabrafenib and pazopanib had no unexpected toxicities, and durable partial responses were observed at DL3 or greater. Dose escalation beyond DL5 may be considered as pazopanib levels were suboptimal as a result of drug interaction with dabrafenib.

Veliparib Alone or in Combination with Mitomycin C in Patients with Solid Tumors With Functional Deficiency in Homologous Recombination Repair.

BACKGROUND: BRCA germline mutations are being targeted for development of PARP inhibitors. BRCA genes collaborate with several others in the Fanconi Anemia (FA) pathway. We screened cancer patients' tumors for FA functional defects then aimed to establish the safety/feasibility of administering PARP inhibitors as monotherapy and combined with a DNA-breaking agent. METHODS: Patients underwent FA functional screening for the presence (or lack) of tumor FancD2 nuclear foci formation on their archival tumor material, utilizing a newly developed method (Fanconi Anemia triple-stain immunofluorescence [FATSI]), performed in a Clinical Laboratory Improvement Amendments-certified laboratory. FATSI-negative patients were selected for enrollment in a two-arm dose escalation trial of veliparib, or veliparib/mitomycin-C (MMC). RESULTS: One hundred eighty-five of 643 (28.7%) screened patients were FATSI-negative. Sixty-one received veliparib or veliparib/MMC through 14 dose levels. Moderate/severe toxicities included fatigue (DLT at veliparib 400mg BID), diarrhea, and thrombocytopenia. Recommended doses are 300mg BID veliparib and veliparib 200mg BID for 21 days following 10mg/m(2) MMC every 28 days. Six antitumor responses occurred, five in the combination arm (3 breast, 1 ovarian, 1 endometrial [uterine], and 1 non-small cell lung cancer). Two patients have received 36 and 60 cycles to date. BRCA germline analysis among 51 patients revealed five deleterious mutations while a targeted FA sequencing gene panel showed missense/nonsense mutations in 29 of 49 FATSI-negative tumor specimens. CONCLUSIONS: FATSI screening showed that a substantial number of patients' tumors have FA functional deficiency, which led to germline alterations in several patients' tumors. Veliparib alone or with MMC was safely administered to these patients and produced clinical benefit in some. However, a better understanding of resistance mechanisms in this setting is needed.

Results of an abbreviated phase-II study with the Akt Inhibitor MK-2206 in Patients with Advanced Biliary Cancer.

Biliary cancers (BC) are rare, chemoresistant and are associated with a poor prognosis. Targeting the Akt pathway is of significance in BC. We hypothesized that the allosteric inhibitor MK-2206 will be active in BC. This was a multi-institutional phase II study of MK-2206 given to patients with advanced, refractory BC. The primary end point was overall response rate. We also characterized pharmacokinetic profiles of MK-2206 in these patients and explored its potential correlation with clinical outcomes. Eight patients were enrolled prior to early termination of the trial. All patients had received prior systemic therapy. The best response observed was stable disease, exceeding 12 weeks in two patients. Toxicities were mild and tolerable. MK-2206 exhibited a pharmacokinetic profile with an apparent slow absorption followed by biphasic elimination in these patients with BC. No significant association was observed between the pharmacokinetic properties of MK-2206 and clinical outcomes. MK-2206 as a single-agent in BC is tolerable with pharmacokinetic properties similar to patients with other solid tumors. No clinical activity was observed in this limited population. Further development of Akt inhibitors may need to focus on combinations with other molecular targeted agents, conventional cytotoxic chemotherapy and prospective patient selection.

Phase I study of azacitidine and bortezomib in adults with relapsed or refractory acute myeloid leukemia.

We previously reported that bortezomib indirectly modulates transcription of DNA methyltransferase 1 (DNMT). We designed a phase I study of azacitidine (a direct DNMT inhibitor) plus bortezomib in acute myeloid leukemia (AML) to determine safety and tolerability. Twenty-three adults with relapsed/refractory AML received azacitidine 75 mg/m(2) daily on days 1-7. Bortezomib was dose escalated from 0.7 mg/m(2) on days 2 and 5 to 1.3 mg/m(2) on days 2, 5, 9 and 12. The target dose was reached without dose limiting toxicities. Infection and/or febrile neutropenia were frequent. Patients received a median of 2 cycles of therapy (range, 1-12+). Five of 23 patients achieved remission, including two with morphologic and cytogenetic complete response (CR) and three with CR and incomplete count recovery (CRi). Of CR/CRi responders with cytogenetic abnormalities at baseline, three of four achieved cytogenetic CR. The combination of azacitidine and bortezomib was tolerable and active in this cohort of poor-risk previously treated patients with AML.

Phase I dose-escalation study of EZN-2208 (PEG-SN38), a novel conjugate of poly(ethylene) glycol and SN38, administered weekly in patients with advanced cancer.

PURPOSE: This study evaluated the tolerability, pharmacokinetics, and preliminary antitumor activity of EZN-2208, a water-soluble poly(ethylene) glycol conjugate of SN38. METHODS: Patients with advanced malignancies were enrolled in dose-escalating cohorts (3 + 3 design). EZN-2208 was administered as a 1-h intravenous infusion given weekly for 3 weeks per each 4-week cycle. Doses ranged from 1 to 12 mg/m(2). RESULTS: Forty-one patients received EZN-2208. All patients had received prior cancer therapy (median = 2, range = 1-11). Twenty patients (49 %) had received prior irinotecan, and one patient had received prior topotecan. One patient in the 9-mg/m(2) cohort had dose-limiting toxicity (grade 3 febrile neutropenia), and one patient in the 12-mg/m(2) cohort had grade 3 neutropenia that resulted in the inability to deliver the third dose of EZN-2208. The most commonly reported drug-related adverse events were nausea (51 %), diarrhea (46 %), fatigue (41 %), alopecia (29 %), neutropenia (24 %), and vomiting (22 %). Administration of EZN-2208 results in prolonged exposure to SN38. Stable disease, sometimes prolonged, was observed as best response. CONCLUSIONS: EZN-2208 has an acceptable safety profile in previously treated patients with advanced malignancies. The recommended phase II dose of EZN-2208 administered according to this schedule was 9 mg/m(2).

Phase II trial of exemestane in combination with fulvestrant in postmenopausal women with advanced, hormone-responsive breast cancer.

INTRODUCTION: Exemestane, the irreversible steroidal aromatase inhibitor, and fulvestrant, the pure estrogen antagonist, are active as single drugs in postmenopausal women with advanced hormone-responsive breast cancer. We designed a phase II study with the purpose of determining whether combining these 2 drugs with different and potentially complementary mechanisms of action will improve the clinical benefit. PATIENTS AND METHODS: Forty postmenopausal women with hormone-responsive advanced breast cancer received intramuscular injection of fulvestrant 250 mg every 28 days in combination with daily exemestane 25 mg until disease progression. We examined the influence of fulvestrant on exemestane pharmacokinetics and the effect of exemestane and fulvestrant on serum IGF-1 (insulin-like growth factor 1) and IGFBP-3 (IGF-binding protein 3) levels. RESULTS: The observed proportion of patients free of progressive disease at 6 months after the initiation of treatment with exemestane and fulvestrant was 50%, a rate similar to that achieved with single-agent exemestane or fulvestrant in the first- or second-line setting. Pharmacokinetics parameters showed that coadministration of fulvestrant did not result in clinically relevant changes in exemestane plasma concentrations. A comparison of IGF-1 and IGFBP-3 levels demonstrated the increase of 35% and 12%, respectively, in mean levels from baseline to day 120. CONCLUSIONS: The combination of exemestane and fulvestrant did not improve clinical benefit. The observed lack of improved efficacy was not related to altered drug exposure.

Phase I dose escalation study of KOS-1584, a novel epothilone, in patients with advanced solid tumors.

PURPOSE: First-in-man study of KOS-1584, a second generation epothilone. METHODS: Patients with advanced solid malignancies received KOS-1584 every 3 weeks until disease progression. Using a modified Fibonacci dose escalation scheme, one patient was enrolled at each dose level until the first instance of grade 2 toxicity. Thereafter, a standard 3 + 3 design was utilized. RESULTS: Sixty-six patients in 14 cohorts were dosed from 0.8 to 48 mg/m(2). Diarrhea, arthralgias, and encephalopathy were dose-limiting toxicities (DLTs) at doses ≥36 mg/m(2). At the recommended phase II dose (RP2D), the most common adverse effects were peripheral neuropathy (low grade), fatigue, arthralgias/myalgias, and diarrhea (31, 6%). The incidence of neutropenia was low. The overall clearance, volume of distribution, and half-life of KOS-1584 were 11 ± 6.17 L/h/m(2), 327 ± 161 L/m(2), and 21.9 ± 8.75 h, respectively. The half-life for the seco-metabolite (KOS-1891) was 29.6 ± 13.8 h. KOS-1584 exhibited linear pharmacokinetics. A dose-dependent increase in microtubulin bundle formation was observed at doses ≥27 mg/m(2). Two patients achieved partial responses and 24 patients had stable disease (SD). CONCLUSIONS: The RP2D of KOS-1584 is 36 mg/m(2). The lack of severe neurologic toxicity, diarrhea, neutropenia, or hypersensitivity reactions; favorable pharmacokinetic profile; and early evidence of activity support further evaluation.

Phase I trial of lenalidomide and CCI-779 in patients with relapsed multiple myeloma: evidence for lenalidomide-CCI-779 interaction via P-glycoprotein.

PURPOSE: Multiple myeloma (MM) is an incurable plasma-cell neoplasm for which most treatments involve a therapeutic agent combined with dexamethasone. The preclinical combination of lenalidomide with the mTOR inhibitor CCI-779 has displayed synergy in vitro and represents a novel combination in MM. PATIENTS AND METHODS: A phase I clinical trial was initiated for patients with relapsed myeloma with administration of oral lenalidomide on days 1 to 21 and CCI-779 intravenously once per week during a 28-day cycle. Pharmacokinetic data for both agents were obtained, and in vitro transport and uptake studies were conducted to evaluate potential drug-drug interactions. RESULTS: Twenty-one patients were treated with 15 to 25 mg lenalidomide and 15 to 20 mg CCI-779. The maximum-tolerated dose (MTD) was determined to be 25 mg lenalidomide with 15 mg CCI-779. Pharmacokinetic analysis indicated increased doses of CCI-779 resulted in statistically significant changes in clearance, maximum concentrations, and areas under the concentration-time curves, with constant doses of lenalidomide. Similar and significant changes for CCI-779 pharmacokinetics were also observed with increased lenalidomide doses. Detailed mechanistic interrogation of this pharmacokinetic interaction demonstrated that lenalidomide was an ABCB1 (P-glycoprotein [P-gp]) substrate. CONCLUSION: The MTD of this combination regimen was 25 mg lenalidomide with 15 mg CCI-779, with toxicities of fatigue, neutropenia, and electrolyte wasting. Pharmacokinetic and clinical interactions between lenalidomide and CCI-779 seemed to occur, with in vitro data indicating lenalidomide was an ABCB1 (P-gp) substrate. To our knowledge, this is the first report of a clinically significant P-gp-based drug-drug interaction with lenalidomide.

Dose escalation of lenalidomide in relapsed or refractory acute leukemias.

PURPOSE: Lenalidomide is effective in myeloma and low-risk myelodysplastic syndromes with deletion 5q. We report results of a phase I dose-escalation trial of lenalidomide in relapsed or refractory acute leukemia. PATIENTS AND METHODS: Thirty-one adults with acute myeloid leukemia (AML) and four adults with acute lymphoblastic leukemia (ALL) were enrolled. Lenalidomide was given orally at escalating doses of 25 to 75 mg daily on days 1 through 21 of 28-day cycles to determine the dose-limiting toxicity (DLT) and maximum-tolerated dose (MTD), as well as to provide pharmacokinetic and preliminary efficacy data. RESULTS: Patients had a median age of 63 years (range, 22 to 79 years) and a median of two prior therapies (range, one to four therapies). The DLT was fatigue; 50 mg/d was the MTD. Infectious complications were frequent. Plasma lenalidomide concentration increased proportionally with dose. In AML, five (16%) of 31 patients achieved complete remission (CR); three of three patients with cytogenetic abnormalities achieved cytogenetic CR (none with deletion 5q). Response duration ranged from 5.6 to 14 months. All responses occurred in AML with low presenting WBC count. No patient with ALL responded. Two of four patients who received lenalidomide as initial therapy for AML relapse after allogeneic transplantation achieved durable CR after development of cutaneous graft-versus-host disease, without donor leukocyte infusion. CONCLUSION: Lenalidomide was safely escalated to 50 mg daily for 21 days, every 4 weeks, and was active with relatively low toxicity in patients with relapsed/refractory AML. Remissions achieved after transplantation suggest a possible immunomodulatory effect of lenalidomide, and results provide enthusiasm for further studies in AML, either alone or in combination with conventional agents or other immunotherapies.

Phase I clinical and pharmacokinetic study of a novel schedule of flavopiridol in relapsed or refractory acute leukemias.

BACKGROUND: A pharmacokinetically derived schedule of flavopiridol administered as a 30 min intravenous bolus followed by 4-hour continuous intravenous infusion (IVB/CIVI) is active in fludarabine-refractory chronic lymphocytic leukemia, but no studies examining the feasibility and maximum tolerated dose of this schedule have been reported in acute leukemia. DESIGN AND METHODS: We conducted a phase I dose escalation trial of single-agent flavopiridol in adults with relapsed/refractory acute leukemias, utilizing a modification of the intravenous bolus/continuous intravenous infusion approach, intensifying treatment for administration on days 1, 2, and 3 of 21-day cycles. RESULTS: Twenty-four adults with relapsed/refractory acute myeloid leukemia (n=19) or acute lymphoblastic leukemia (n=5) were enrolled. The median age was 62 years (range, 23-78). The maximum tolerated dose of flavopiridol was 40 mg/m(2) intravenous bolus plus 60 mg/m(2) continuous intravenous infusion (40/60). The dose limiting toxicity was secretory diarrhea. Life-threatening hyperacute tumor lysis syndrome requiring hemodialysis on day 1 was observed in one patient. Pharmacokinetics were dose-dependent with increased clearance observed at the two highest dose levels. Diarrhea occurrence and severity significantly correlated with flavopiridol concentrations at the end of the 4-hour infusion, volume of distribution, and elimination half-life. Modest anti-leukemic activity was observed, with most patients experiencing dramatic but transient reduction/clearance of circulating blasts lasting for 10-14 days. One refractory acute myeloid leukemia patient had short-lived complete remission with incomplete count recovery. CONCLUSIONS: Flavopiridol as a single agent given by intravenous bolus/continuous intravenous infusion causes marked, immediate cytoreduction in relapsed/refractory acute leukemias, but objective clinical responses were uncommon. With this schedule, the dose is limited by secretory diarrhea.

Clinical response and miR-29b predictive significance in older AML patients treated with a 10-day schedule of decitabine.

A phase II clinical trial with single-agent decitabine was conducted in older patients (>or=60 years) with previously untreated acute myeloid leukemia (AML) who were not candidates for or who refused intensive chemotherapy. Subjects received low-dose decitabine at 20 mg/m(2) i.v. over 1 h on days 1 to 10. Fifty-three subjects enrolled with a median age of 74 years (range, 60-85). Nineteen (36%) had antecedent hematologic disorder or therapy-related AML; 16 had complex karyotypes (>or=3 abnormalities). The complete remission rate was 47% (n = 25), achieved after a median of three cycles of therapy. Nine additional subjects had no morphologic evidence of disease with incomplete count recovery, for an overall response rate of 64% (n = 34). Complete remission was achieved in 52% of subjects presenting with normal karyotype and in 50% of those with complex karyotypes. Median overall and disease-free survival durations were 55 and 46 weeks, respectively. Death within 30 days of initiation of treatment occurred in one subject (2%), death within 8 weeks in 15% of subjects. Given the DNA hypomethylating effect of decitabine, we examined the relationship of clinical response and pretreatment level of miR-29b, previously shown to target DNA methyltransferases. Higher levels of miR-29b were associated with clinical response (P = 0.02). In conclusion, this schedule of decitabine was highly active and well tolerated in this poor-risk cohort of older AML patients. Levels of miR-29b should be validated as a predictive factor for stratification of older AML patients to decitabine treatment.

Flavopiridol, fludarabine, and rituximab in mantle cell lymphoma and indolent B-cell lymphoproliferative disorders.

PURPOSE: Flavopiridol downmodulates antiapoptotic proteins associated with resistance to fludarabine and rituximab and is effective against p53-mutated chronic lymphocytic leukemia (CLL). We conducted a phase I study of flavopiridol, fludarabine, and rituximab (FFR) in patients with mantle-cell lymphoma (MCL), indolent B-cell non-Hodgkin's lymphomas (B-NHL), and CLL to determine the activity of FFR. PATIENTS AND METHODS: Therapy included fludarabine 25 mg/m(2) intravenously (IV) days 1 to 5 and rituximab 375 mg/m(2) day 1 every 28 days for 6 cycles. We administered flavopiridol 50 mg/m(2) by 1-hour IV bolus (IVB) day 1 (n = 15); day 1 to 2 (n = 6); 20 mg/m(2) 30-minute IVB + 20 mg/m(2) 4-hour IV infusion (n = 3); or 30 mg/m(2) + 30 mg/m(2) (n = 14). RESULTS: Thirty-eight patients (median age, 62 years) with MCL (n = 10); indolent B-NHL including follicular (n = 9), marginal zone (n = 4), lymphoplasmacytic (n = 1), or small lymphocytic lymphoma (n = 3); and CLL (n = 11), were enrolled. Twenty-two patients were previously untreated; 16 had received one to two prior therapies. Two patients in cohort 2 developed grade 3 dose-limiting toxicity (seizures, renal insufficiency). The median number of treatment cycles was 4, with cytopenias (n = 10) and fatigue (n = 3) the most common reasons for early discontinuation. Overall response rate was 82% (complete response, 50%; unconfirmed complete response, 5%; partial response, 26%), including 80% of patients with MCL (median age, 68; seven complete responses, one partial response). Median progression-free survival (PFS) was 25.6 months. Median PFS of patients with nonblastoid variant MCL (n = 8) was 35.9 months. CONCLUSION: FFR was active in MCL, indolent B-NHL, and CLL and should be studied for older patients with MCL who are not candidates for aggressive chemotherapy.

A dose-finding and pharmacodynamic study of bortezomib in combination with weekly paclitaxel in patients with advanced solid tumors.

PURPOSE: A phase I study to determine the maximum tolerated dose (MTD) of bortezomib (B) when combined with weekly paclitaxel in patients with advanced solid tumors. PATIENTS AND METHODS: Eligible patients received escalating doses of intravenous (IV) bortezomib (0.6-2 mg/m(2)) on days 2 and 9 and IV paclitaxel at 100 mg/m(2) on days 1 and 8 of a 21-day cycle. Dose escalation was based on two end-points: not exceeding 80% 20S-proteasome inhibition (20-S PI) and the development of dose-limiting toxicity defined as grade 3 or greater non-hematologic or grade 4 hematologic toxicities. RESULTS: Forty-five patients with advanced solid tumors and a median of 3 prior chemotherapy regimens (range 0-9), received 318 doses (median 5, range 1-34) of bortezomib and paclitaxel. Dose-related inhibition of 20-S PI was observed with a maximum inhibition of 70-80% at the MTD of 1.8 mg/m(2) of bortezomib. At the MTD (N = 9) the following toxicities were observed: grade 4 neutropenia without fever (n = 2) and cerebrovascular ischemia (n = 1); grade 3 neutropenia (n = 3), diarrhea (n = 2), nausea (n = 1), and fatigue (n = 1); grade 2 fatigue (n = 5), diarrhea (n = 4), and dyspnea (n = 2). There was one partial response in a patient with an eccrine porocarcinoma. Stabilization of disease was observed in 7 (16%) patients, 3 of whom had advanced pancreatic cancer. CONCLUSION: Sequential paclitaxel and bortezomib in previously treated patients with advanced solid tumors resulted in acceptable toxicity and no evidence of interaction. The recommended phase II dose of bortezomib in combination with weekly paclitaxel was 1.8 mg/m(2).

Phase II study of flavopiridol in relapsed chronic lymphocytic leukemia demonstrating high response rates in genetically high-risk disease.

PURPOSE: Patients with chronic lymphocytic leukemia (CLL) with high-risk genomic features achieve poor outcomes with traditional therapies. A phase I study of a pharmacokinetically derived schedule of flavopiridol suggested promising activity in CLL, irrespective of high-risk features. Given the relevance of these findings to treating genetically high-risk CLL, a prospective confirmatory study was initiated. PATIENTS AND METHODS: Patients with relapsed CLL were treated with single-agent flavopiridol, with subsequent addition of dexamethasone to suppress cytokine release syndrome (CRS). High-risk genomic features were prospectively assessed for response to therapy. RESULTS: Sixty-four patients were enrolled. Median age was 60 years, median number of prior therapies was four, and all patients had received prior purine analog therapy. If patients tolerated treatment during week 1, dose escalation occurred during week 2. Dose escalation did not occur in four patients, as a result of severe tumor lysis syndrome; three of these patients required hemodialysis. Thirty-four patients (53%) achieved response, including 30 partial responses (PRs; 47%), three nodular PRs (5%), and one complete response (1.6%). A majority of high-risk patients responded; 12 (57%) of 21 patients with del(17p13.1) and 14 (50%) of 28 patients with del(11q22.3) responded irrespective of lymph node size. Median progression-free survival among responders was 10 to 12 months across all cytogenetic risk groups. Reducing the number of weekly treatments per cycle from four to three and adding prophylactic dexamethasone, which abrogated interleukin-6 release and CRS (P < or = .01), resulted in improved tolerability and treatment delivery. CONCLUSION: Flavopiridol achieves significant clinical activity in patients with relapsed CLL, including those with high-risk genomic features and bulky lymphadenopathy. Subsequent clinical trials should use the amended treatment schedule developed herein and prophylactic corticosteroids.

Enterohepatic recirculation model of irinotecan (CPT-11) and metabolite pharmacokinetics in patients with glioma.

BACKGROUND: Enterohepatic recirculation of irinotecan and one of its metabolites, SN-38, has been observed in pharmacokinetic data sets from previous studies. A mathematical model that can incorporate this phenomenon was developed to describe the pharmacokinetics of irinotecan and its metabolites. PATIENTS AND METHODS: A total of 32 patients with recurrent malignant glioma were treated with weekly intravenous administration of irinotecan at a dose of 125 mg/m(2). Plasma concentrations of irinotecan and its three major metabolites were determined. Pharmacokinetic models were developed and tested for simultaneous fit of parent drug and metabolites, including a recirculation component. RESULTS: Rebound in the plasma concentration suggestive of enterohepatic recirculation at approximately 0.5-1 h post-infusion was observed in most irinotecan plasma concentration profiles, and in some plasma profiles of the SN-38 metabolite. A multi-compartment model containing a recirculation chain was developed to describe this process. The recirculation model was optimal in 22 of the 32 patients compared to the traditional model without the recirculation component. CONCLUSION: A recirculation chain incorporated in a multi-compartment pharmacokinetic model of irinotecan and its metabolites appears to improve characterization of this drug's disposition in patients with glioma.

Clinical response and pharmacokinetics from a phase 1 study of an active dosing schedule of flavopiridol in relapsed chronic lymphocytic leukemia.

We previously reported interim results of a phase 1 trial in patients with chronic lymphocytic leukemia (CLL) whereby flavopiridol was administered intravenously as a 30-minute bolus followed by 4-hour infusion. We now report full pharmacokinetic (PK) data, correlations of PK with clinical outcomes, and final response and progression-free survival (PFS). Twenty-one (40%) of 52 patients with relapsed CLL achieved a partial response (PR) with a median PFS of 12 months. Responders included 17 (40%) of 43 fludarabine refractory patients, 7 (39%) of 18 patients with del(17p13), and 14 (74%) of 19 patients with del(11q22). Six responders received repeat therapy at relapse, and 5 responded again with a second median PFS of 10 months. Noncompartmental analysis and nonlinear mixed effects modeling was used to estimate PK parameters and evaluate covariates. Two-compartment population parameter estimates were 31.4 L/h, 65.8 L, 8.49 L/h, and 157 L for CL, V1, Q, and V2, respectively. Flavopiridol area under the plasma concentration-time curve (AUC) correlated with clinical response and cytokine release syndrome, and glucuronide metabolite AUC correlated with tumor lysis syndrome. These composite results confirm high activity of this pharmacokinetically derived schedule in relapsed, genetically high-risk CLL. Furthermore, PK describes some, but not all, variability in response and toxicity.

Development and validation of a highly sensitive liquid chromatography/mass spectrometry method for simultaneous quantification of lenalidomide and flavopiridol in human plasma.

Lenalidomide, an immunomodulatory agent, and flavopiridol, a broad cyclin-dependent kinase inhibitor, are active therapies for clinical use in genomic high-risk chronic lymphocytic leukemia. A high-performance liquid chromatographic assay with tandem mass spectrometric detection has been developed to simultaneously quantify lenalidomide and flavopiridol in human and mouse plasma to facilitate their combined clinical development. Samples were prepared by liquid-liquid extraction with acetonitrile (ACN)-containing internal standard, genistein, followed by evaporation of solvent and reconstitution in 95/5 H2O/ACN. Lenalidomide and internal standard were separated by reversed-phase liquid chromatography on a C-18 column using a gradient of H2O and ACN, each with 0.1% formic acid. Atmospheric pressure chemical ionization in positive ion mode with single reaction monitoring on a triple quadrupole mass spectrometer was applied to detect transitions of lenalidomide (260.06 > 149.10) and flavopiridol (402.09 > 341.02). Lower limits of quantification of lenalidomide and flavopiridol were 1 and 0.3 nM, respectively. Recoveries of lenalidomide and flavopiridol from human plasma ranged from 99% to 116% throughout their linear ranges. Within- and between-run precision and accuracy of replicate samples were all less than 15%. This is the most sensitive analytical method reported to date for both lenalidomide and flavopiridol. This sensitivity will enable late terminal phase concentration measurements and accurate pharmacokinetic parameter estimation in a planned clinical trial with lenalidomide and flavopiridol in patients with chronic lymphocytic leukemia.

Clinical pharmacodynamic effects of the growth hormone receptor antagonist pegvisomant: implications for cancer therapy.

PURPOSE: The present study evaluated and compared the efficacy of pegvisomant and octreotide in blocking the growth hormone (GH) axis in humans based on pharmacodynamic biomarkers associated with the GH axis. The study also evaluated the safety of pegvisomant given at high s.c. doses for 14 days. EXPERIMENTAL DESIGN: Eighty healthy subjects were enrolled in five cohorts: cohorts 1 to 3, s.c. pegvisomant at 40, 60, or 80 mg once dailyx14 days (n=18 per cohort); cohort 4, s.c. octreotide at 200 microg thrice dailyx14 days (n=18); and cohort 5, untreated control (n=8). Serial blood samples were collected to measure plasma concentrations of total insulin-like growth factor type I (IGF-I), free IGF-I, IGF-II, IGF-binding protein 3 (IGFBP-3), and GH in all subjects and serum pegvisomant concentrations in subjects of cohorts 1 to 3. All subjects receiving treatment were monitored for adverse events (AE). RESULTS: After s.c. dosing of pegvisomant once daily for 14 days, the mean maximum suppression values of total IGF-I were 57%, 60%, and 62%, at 40, 60, and 80 mg dose levels, respectively. The maximum suppression was achieved approximately 7 days after the last dose and was sustained for approximately 21 days. Pegvisomant also led to a sustained reduction in free IGF-I, IGFBP-3, and IGF-II concentrations by up to 33%, 46%, and 35%, respectively, and an increase in GH levels. In comparison, octreotide resulted in a considerably weaker inhibition of total IGF-I and IGFBP-3 for a much shorter duration, and no inhibition of IGF-II. AEs in pegvisomant-treated subjects were generally either grade 1 or 2. The most frequent treatment-related AEs included injection site reactions, headache, and fatigue. CONCLUSIONS: Pegvisomant at well-tolerated s.c. doses was considerably more efficacious than octreotide in suppressing the GH axis, resulting in substantial and sustained inhibition of circulating IGF-I, IGF-II, and IGFBP-3 concentrations. These results provide evidence in favor of further testing the hypothesis that pegvisomant, through blocking the GH receptor-mediated signal transduction pathways, could be effective in treating tumors that may be GH, IGF-I, and/or IGF-II dependent, such as breast and colorectal cancer.

Flavopiridol administered using a pharmacologically derived schedule is associated with marked clinical efficacy in refractory, genetically high-risk chronic lymphocytic leukemia.

Despite promising preclinical studies with the cyclin-dependent kinase inhibitor flavopiridol in chronic lymphocytic leukemia (CLL) and other diseases, previous clinical trials with this agent have been disappointing. The discovery of differential protein binding of flavopiridol in human and bovine serum contributed to an effective pharmacokinetic-derived schedule of administration of this agent. On the basis of pharmacokinetic modeling using our in vitro results and data from a previous trial, we initiated a phase 1 study using a 30-minute loading dose followed by 4 hours of infusion administered weekly for 4 of 6 weeks in patients with refractory CLL. A group of 42 patients were enrolled on 3 cohorts (cohort 1, 30 mg/m2 loading dose followed by 30 mg/m2 4-hour infusion; cohort 2, 40 mg/m2 loading dose followed by 40 mg/m2 4-hour infusion; and cohort 3, cohort 1 dose for treatments 1 to 4, then a 30 mg/m2 loading dose followed by a 50 mg/m2 4-hour infusion). The dose-limiting toxicity using this novel schedule was hyperacute tumor lysis syndrome. Aggressive prophylaxis and exclusion of patients with leukocyte counts greater than 200x10(9)/L have made this drug safe to administer at the cohort 3 dose. Of the 42 patients treated, 19 (45%) achieved a partial response with a median response duration that exceeds 12 months. Responses were noted in patients with genetically high-risk disease, including 5 (42%) of 12 patients with del(17p13.1) and 13 (72%) of 18 patients with del(11q22.3). Flavopiridol administered using this novel schedule has significant clinical activity in refractory CLL. Patients with bulky disease and high-risk genetic features have achieved durable responses, thereby justifying further study of flavopiridol in CLL and other diseases.