Paediatric Strategy Forum for medicinal product development for acute myeloid leukaemia in children and adolescents: ACCELERATE in collaboration with the European Medicines Agency with participation of the Food and Drug Administration

Purpose:

The current standard-of-care for front-line therapy for acute myeloid leukaemia (AML) results in short-term and long-term toxicity, but still approximately 40% of children relapse. Therefore, there is a major need to accelerate the evaluation of innovative medicines, yet drug development continues to be adult-focused. Furthermore, the large number of competing agents in rare patient populations requires coordinated prioritisation, within the global regulatory framework and cooperative group initiatives.

Methods:

The fourth multi-stakeholder Paediatric Strategy Forum focused on AML in children and adolescents.

Results:

CD123 is a high priority target and the paediatric development should be accelerated as a proof-of-concept. Efforts must be coordinated, however, as there are a limited number of studies that can be delivered. Studies of FLT3 inhibitors in agreed paediatric investigation plans present challenges to be completed because they require enrolment of a larger number of patients than actually exist. A consensus was developed by industry and academia of optimised clinical trials. For AML with rare mutations that are more frequent in adolescents than in children, adult trials should enrol adolescents and when scientifically justified, efficacy data could be extrapolated. Methodologies and definitions of minimal residual disease need to be standardised internationally and validated as a new response criterion. Industry supported, academic sponsored platform trials could identify products to be further developed. The Leukaemia and Lymphoma Society PedAL/EUpAL initiative has the potential to be a major advance in the field.

Conclusion:

These initiatives continue to accelerate drug development for children with AML and ultimately improve clinical outcomes.

ACCELERATE and European Medicines Agency Paediatric Strategy Forum for medicinal product development of checkpoint inhibitors for use in combination therapy in paediatric patients

The third multistakeholder Paediatric Strategy Forum organised by ACCELERATE and the European Medicines Agency focused on immune checkpoint inhibitors for use in combination therapy in children and adolescents. As immune checkpoint inhibitors, both as monotherapy and in combinations have shown impressive success in some adult malignancies and early phase trials in children of single agent checkpoint inhibitors have now been completed, it seemed an appropriate time to consider opportunities for paediatric studies of checkpoint inhibitors used in combination. Among paediatric patients, early clinical studies of checkpoint inhibitors used as monotherapy have demonstrated a high rate of activity, including complete responses, in Hodgkin lymphoma and hypermutant paediatric tumours. Activity has been very limited, however, in more common malignancies of childhood and adolescence. Furthermore, apart from tumour mutational burden, no other predictive biomarker for monotherapy activity in paediatric tumours has been identified. Based on these observations, there is collective agreement that there is no scientific rationale for children to be enrolled in new monotherapy trials of additional checkpoint inhibitors with the same mechanism of action of agents already studied (e.g. anti-PD1, anti-PDL1 anti-CTLA-4) unless additional scientific knowledge supporting a different approach becomes available. This shared perspective, based on scientific evidence and supported by paediatric oncology cooperative groups, should inform companies on whether a paediatric development plan is justified. This could then be proposed to regulators through the available regulatory tools. Generally, an academic-industry consensus on the scientific merits of a proposal before submission of a paediatric investigational plan would be of great benefit to determine which studies have the highest probability of generating new insights. There is already a rationale for the evaluation of combinations of checkpoint inhibitors with other agents in paediatric Hodgkin lymphoma and hypermutated tumours in view of the activity shown as single agents. In paediatric tumours where no single agent activity has been observed in multiple clinical trials of anti-PD1, anti-PDL1 and anti-CTLA-4 agents as monotherapy, combinations of checkpoint inhibitors with other treatment modalities should be explored when a scientific rationale indicates that they could be efficacious in paediatric cancers and not because these combinations are being evaluated in adults. Immunotherapy in the form of engineered proteins (e.g. monoclonal antibodies and T cell engaging agents) and cellular products (e.g. CAR T cells) has great therapeutic potential for benefit in paediatric cancer. The major challenge for developing checkpoint inhibitors for paediatric cancers is the lack of neoantigens (based on mutations) and corresponding antigen-specific T cells. Progress critically depends on understanding the immune macroenvironment and microenvironment and the ability of the adaptive immune system to recognise paediatric cancers in the absence of high neoantigen burden. Future clinical studies of checkpoint inhibitors in children need to build upon strong biological hypotheses that take into account the distinctive immunobiology of childhood cancers in comparison to that of checkpoint inhibitor responsive adult cancers.

Implementation of mechanism of action biology-driven early drug development for children with cancer

An urgent need remains for new paediatric oncology drugs to cure children who die from cancer and to reduce drug-related sequelae in survivors. In 2007, the European Paediatric Regulation came into law requiring industry to create paediatric drug (all types of medicinal products) development programmes alongside those for adults. Unfortunately, paediatric drug development is still largely centred on adult conditions and not a mechanism of action (MoA)-based model, even though this would be more logical for childhood tumours as these have much fewer non-synonymous coding mutations than adult malignancies. Recent large-scale sequencing by International Genome Consortium and Paediatric Cancer Genome Project has further shown that the genetic and epigenetic repertoire of driver mutations in specific childhood malignancies differs from more common adult-type malignancies. To bring about much needed change, a Paediatric Platform, ACCELERATE, was proposed in 2013 by the Cancer Drug Development Forum, Innovative Therapies for Children with Cancer, the European Network for Cancer Research in Children and Adolescents and the European Society for Paediatric Oncology. The Platform, comprising multiple stakeholders in paediatric oncology, has three working groups, one with responsibility for promoting and developing high-quality MoA-informed paediatric drug development programmes, including specific measures for adolescents. Key is the establishment of a freely accessible aggregated database of paediatric biological tumour drug targets to be aligned with an aggregated pipeline of drugs. This will enable prioritisation and conduct of early phase clinical paediatric trials to evaluate these drugs against promising therapeutic targets and to generate clinical paediatric efficacy and safety data in an accelerated time frame. Through this work, the Platform seeks to ensure that potentially effective drugs, where the MoA is known and thought to be relevant to paediatric malignancies, are evaluated in early phase clinical trials, and that this approach to generate pre-clinical and clinical data is systematically pursued by academia, sponsors, industry, and regulatory bodies to bring new paediatric oncology drugs to front-line therapy more rapidly.

Population pharmacokinetics of intravenous and oral panobinostat in patients with hematologic and solid tumors

PURPOSE

The study aimed to characterize the population pharmacokinetics of panobinostat, a pan-deacetylase inhibitor that has demonstrated efficacy in combination with bortezomib and dexamethasone in patients with multiple myeloma.

METHODS

A nonlinear mixed-effect model was used to fit plasma panobinostat concentration-time data collected from patients across 14 phase 1 and phase 2 trials following either oral or intravenous (IV) administration. The model was used to estimate bioavailabilities of the two oral formulations and the effects of demographic and clinical covariates on the central volume of distribution and clearance of panobinostat.

RESULTS

A total of 7834 samples from 581 patients were analyzed. Panobinostat pharmacokinetic parameters were best characterized by a three-compartment model with first-order absorption and elimination. Bioavailability was 21.4 %. Median clearance was 33.1 L/h. Interindividual variability in clearance was 74 %. For Caucasian patients of median age 61 years, area under the curve (AUC) decreased from 104 to 88 ng · h/mL as body surface area (BSA) increased from the first to third quartiles, 1.8 to 2.1 m(2). For Caucasian patients of median BSA 1.9 m(2), AUC decreased from 102 to 95 ng · h/mL as age increased from the first to third quartiles, 51 to 70 years. For patients of median BSA and median age, AUC ranged across the four race categories from 80 to 116 ng · h/mL. Covariate analysis showed no impact on panobinostat clearance and volume by patients' sex, tumor type, kidney function, liver markers, or coadministered medications. However, separate analyses of dedicated studies have demonstrated effects of liver impairment and CYP3A4 inhibition.

CONCLUSIONS

Although covariate analyses revealed significant effects of body size, age, and race on panobinostat pharmacokinetics, these effects were minor compared to the interindividual variability and therefore not clinically relevant when dosing panobinostat in populations similar to those studied.

Absolute Bioavailability of Imatinib (Glivec®) Orally versus Intravenous Infusion

The purpose of this study was to investigate the absolute bioavailability of a single oral dose of imatinib (Glivec), 400 mg (capsules vs. oral solution), compared with imatinib, 100 mg (intravenous [i.v.] infusion), in healthy subjects. Twelve subjects received a single treatment in each treatment period: a 400-mg oral dose of imatinib in capsule form or as a solution or a 100-mg i.v. infusion of imatinib. Plasma imatinib concentrations were measured following each treatment; pharmacokinetic parameters and absolute bioavailability were determined. Absolute bioavailability values (compared with i.v. infusion) for the imatinib capsule and oral solution were 98.3% and 97.2%, respectively. Both the rate and extent of imatinib absorption, as measured by C(max), partial AUC, and total AUC, were similar for the oral solution and the imatinib capsule intended for the market. The 400-mg oral dose of imatinib, as a capsule or a solution, was completely absorbed and was almost completely bioavailable (> 97%).

Report of an international expanded access program of imatinib in adults with Philadelphia chromosome positive leukemias

BACKGROUND

Imatinib is a selective inhibitor of the BCR/ABL tyrosine kinase. The remarkable initial results of the first phase I clinical trial published in 1999 prompted the rapid initiation of large phase II trials. They also generated intense media coverage and significant interest from patients and clinicians and demand for access to imatinib before marketing approval. In response, a worldwide expanded access program (EAP) for imatinib was implemented in May 2000.

PATIENTS

In total, 7380 patients with chronic myeloid leukemia (CML) and acute lymphoblastic leukemia failing prior therapies were enrolled in 106 centers in 34 countries.

RESULTS

Time to progression and overall survival, as well as the safety profile, were similar to those observed in published phase II studies. At the end of the program, patients benefiting from treatment were continued on imatinib therapy by transferring to national health care systems or patient assistance programs.

CONCLUSION

The imatinib EAP successfully provided therapy to patients with CML before marketing approval. The program provides an efficient framework for the development of global EAPs for innovative investigational anticancer agents in patients without a satisfactory therapeutic alternative.

A phase I and pharmacokinetic study of LAF389 administered to patients with advanced cancer

LAF389 is a synthetic analogue of bengamide B, a natural product isolated from Jaspidae sponges. LAF389 has both antiproliferative and antiangiogenetic properties, and preclinical investigations showed a broad antitumour activity. This clinical trial aimed to determine the safety and pharmacokinetic profile of LAF389 administered as a slow intravenous injection for 3 consecutive days every 3 weeks in patients with advanced solid tumours. Eight dose levels were tested: 1, 2.5, 5, 10, 15, 30, 25 and 20 mg/day. A total of 33 patients, median age 52 years (range 33-72), with refractory solid tumours were enroled, 19 men and 14 women with a median World Health Organization performance status of 1 (0-4). Seventy-eight cycles of treatment have been administered (mean 2.5, range 1-10). Four cardiovascular dose-limiting toxicities were reported at 30 mg (2/2 patients) and 25 mg (2/9 patients), eight additional patients at various dose levels had (cardio)vascular toxicity, probably drug related, and one patient died owing to pulmonary embolism at the 5 mg dose. No objective responses were recorded. Pharmacokinetic parameters were variable, although linear and without obvious accumulation from cycle I to cycle II. LAF389 dose escalation was terminated owing to occurrence of unpredictable cardiovascular events. This, associated with the lack of clinical activity, did not warrant further investigation of this agent.

Phase I/II Study of Imatinib Mesylate for Recurrent Malignant Gliomas: North American Brain Tumor Consortium Study 99-08

PURPOSE

Phase I: To determine the maximum tolerated doses, toxicities, and pharmacokinetics of imatinib mesylate (Gleevec) in patients with malignant gliomas taking enzyme-inducing antiepileptic drugs (EIAED) or not taking EIAED. Phase II: To determine the therapeutic efficacy of imatinib.

EXPERIMENTAL DESIGN

Phase I component used an interpatient dose escalation scheme. End points of the phase II component were 6-month progression-free survival and response.

RESULTS

Fifty patients enrolled in the phase I component (27 EIAED and 23 non-EIAED). The maximum tolerated dose for non-EIAED patients was 800 mg/d. Dose-limiting toxicities were neutropenia, rash, and elevated alanine aminotransferase. EIAED patients received up to 1,200 mg/d imatinib without developing dose-limiting toxicity. Plasma exposure of imatinib was reduced by approximately 68% in EIAED patients compared with non-EIAED patients. Fifty-five non-EIAED patients (34 glioblastoma multiforme and 21 anaplastic glioma) enrolled in the phase II component. Patients initially received 800 mg/d imatinib; 15 anaplastic glioma patients received 600 mg/d after hemorrhages were observed. There were 2 partial response and 6 stable disease among glioblastoma multiforme patients and 0 partial response and 5 stable disease among anaplastic glioma patients. Six-month progression-free survival was 3% for glioblastoma multiforme and 10% for anaplastic glioma patients. Five phase II patients developed intratumoral hemorrhages.

CONCLUSIONS

Single-agent imatinib has minimal activity in malignant gliomas. CYP3A4 inducers, such as EIAEDs, substantially decreased plasma exposure of imatinib and should be avoided in patients receiving imatinib for chronic myelogenous leukemia and gastrointestinal stromal tumors. The evaluation of the activity of combination regimens incorporating imatinib is under way in phase II trials.

Population pharmacokinetics of imatinib mesylate in patients with chronic-phase chronic myeloid leukaemia: results of a phase III study

AIMS

This study was designed to investigate the biochemical and physiological covariates or comedications that affect the pharmacokinetics of imatinib mesylate in patients with chronic-phase chronic myeloid leukaemia (CP CML).

METHODS

Pharmacokinetic data were analyzed in 371 patients receiving 400 mg imatinib once daily during a phase III trial of imatinib vs interferon-alfa plus cytarabine for the treatment of newly diagnosed CP CML. Covariates included age, weight, sex, ethnicity, haemoglobin (Hb) concentration, white blood cell (WBC) count, liver function, and creatinine concentration. Blood samples for imatinib analysis were taken on treatment days 1 and 29. Nonlinear mixed effects modelling was used for the population pharmacokinetic analysis.

RESULTS

Population mean estimates (95% confidence interval) at day 1 for apparent clearance (CL) and apparent volume of distribution (V) of imatinib were 14 (13-15) l h(-1) and 252 (237-267) l, respectively. Modelling suggested that CL decreased by 4 (3-5) l h(-1) from day 1 to day 29, whereas V remained unchanged. Interindividual variability in CL and V was 32% and 31%, respectively. Weight, Hb, and WBC count demonstrated small effects on CL and V. Doubling body weight or Hb or halving the WBC count was associated with a 12%, 86% and 8% increase in CL, respectively, and a 32%, 60% and 5% increase in V, respectively. Comedications showed no clear effects on imatinib CL.

CONCLUSIONS

Population covariates and coadministered drugs minimally affected imatinib pharmacokinetics in newly diagnosed CP CML patients.

Clinical efficacy, tolerability, and safety of SAM486A, a novel polyamine biosynthesis inhibitor, in patients with relapsed or refractory non-Hodgkin's lymphoma: results from a phase II multicenter study

PURPOSE

SAM486A is a new inhibitor of S-adenosyl-methionine-decarboxylase, a key enzyme for polyamine biosynthesis. It is more potent than the first generation S-adenosyl-methionine-decarboxylase inhibitor methylglyoxal bis-guanylhydrazone. This Phase IIa study reports the findings of SAM486A monotherapy in patients with refractory or relapsed non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Forty-one previously treated patients with either diffuse large cell, follicular, or peripheral T-cell NHL were treated i.v. with 100 mg/m(2) SAM486A as a daily 1-h infusion for 5 days repeated every 3 weeks. Treatment was continued for a total of eight cycles or until disease progression.

RESULTS

Two patients, both with large B-cell lymphoma, showed a complete response at cycle 3 that was maintained for >or=13 and >or=28 months. Five patients had a partial response, and 3 had stable disease at last follow-up. The overall response rate (complete response plus partial response) was 18.9% for evaluable patients (7 patients). Anemia was the primary hematological toxicity and observed in 7 (17.1%) patients. Five patients experienced grade 3/4 anemia. Four patients (9.8%) experienced grade 3/4 febrile neutropenia and grade 3/4 thrombocytopenia, respectively. Nonhematological toxicities were mild to moderate in intensity. The most frequent side effects were nausea (39%), vomiting (22%), diarrhea (19.5%), asthenia (17.1%), abdominal pain (14.6%), and flushing (9.8%).

CONCLUSION

SAM486A has a promising clinical activity in patients with poor prognosis NHL and manageable safety profile. To further define the role of SAM486A, in the treatment of NHL, additional studies are warranted.

Imatinib mesylate (STI571) for treatment of children with Philadelphia chromosome-positive leukemia: results from a Children's Oncology Group phase 1 study

The purpose of this study was to determine dose-limiting toxicities and pharmacokinetics of imatinib in children with refractory or recurrent Philadelphia chromosome-positive (Ph(+)) leukemias. Oral imatinib was administered daily at dose levels ranging from 260 to 570 mg/m(2). Plasma pharmacokinetic studies were performed on days 1 and 8 of course 1. There were 31 children who received 479 courses of imatinib. The most common toxicities encountered, which occurred in less than 5% of courses, were grade 1 or 2 nausea, vomiting, fatigue, diarrhea, and reversible increases in serum transaminases. One patient at the 440-mg/m(2) dose level had dose-limiting weight gain. There were no other first-course dose-limiting toxicities. A maximum tolerated dosage was not defined. Among 12 chronic myeloid leukemia (CML) patients evaluable for cytogenetic response, 10 had a complete response and 1 had a partial response. Among 10 acute lymphoblastic leukemia (ALL) patients evaluable for morphologic response, 7 achieved an M1 and 1 achieved an M2 bone marrow. We observed marked interpatient variability in the pharmacokinetic parameters. In conclusion, we found that daily oral imatinib is well tolerated in children at doses ranging from 260 to 570 mg/m(2). Doses of 260 and 340 mg/m(2) provide systemic exposures similar to those of adults who are treated with daily doses of 400 and 600 mg, respectively.

Pharmacokinetic interaction between ketoconazole and imatinib mesylate (Glivec) in healthy subjects

The study under discussion was a drug-drug interaction study in which the effect of ketoconazole, a potent CYP450 3A4 inhibitor, on the pharmacokinetics of Glivec (imatinib) was investigated. A total of 14 healthy subjects (13 male, 1 female) were enrolled in this study. Each subject received a single oral dose of imatinib 200 mg alone, and a single oral dose of imatinib 200 mg coadministered with a single oral dose of ketoconazole 400 mg according to a two-period crossover design. The treatment sequence was randomly allocated. Subtherapeutic imatinib doses and a short exposure were tested in order not to overexpose the healthy volunteers. There was a minimum 7-day washout period between the two sequences. Blood samples for determination of plasma concentrations were taken up to 96 h after dosing. Imatinib and CGP74588 (main metabolite of imatinib) concentrations were measured using LC/MS/MS method and pharmacokinetic parameters were estimated by a non-compartmental analysis. Following ketoconazole coadministration, the mean imatinib C(max), AUC((0-24)) and AUC((0- infinity )) increased significantly by 26% ( P<0.005), 40% ( P<0.0005) and 40% ( P <0.0005), respectively. There was a statistically significant decrease in apparent clearance (CL/f) of imatinib with a mean reduction of 28.6% ( P<0.0005). The mean C(max) and AUC((0-24)) of the metabolite CGP74588 decreased significantly by 22.6% ( P<0.005) and 13% ( P<0.05) after ketoconazole treatment, although the AUC((0- infinity )) of CGP74588 only decreased by 5% ( P=0.28). Coadministration of ketoconazole and imatinib caused a 40% increase in exposure to imatinib in healthy volunteers. Given its previously demonstrated safety profile, this increased exposure to imatinib is likely to be clinically significant only at high doses. This interaction should be considered when administering inhibitors of the CYP3A family in combination with imatinib.

Bioequivalence, safety, and tolerability of imatinib tablets compared with capsules

PURPOSE

Imatinib (Glivec) has been established as a highly effective therapy for chronic myeloid leukemia and gastrointestinal tumors. The recommended daily dosage of 400-600 mg requires simultaneous intake of up to six of the current 100-mg capsules. Due to the need to swallow multiple capsules per dose, there is a potential negative impact on treatment adherence; therefore, a new imatinib 400-mg film-coated tablet has been developed. To improve dosing flexibility, particularly with regard to the pediatric population and the management of adverse events, a scored 100-mg film-coated tablet has also been introduced.

EXPERIMENTAL DESIGN

A group of 33 healthy subjects were randomly assigned to one of six treatment sequences, in which they received imatinib as 4 x 100-mg capsules (reference), 4 x 100-mg scored tablets (test), and 1 x 400-mg tablet (test). Blood sampling was performed for up to 96 h after dosing, followed by a 10-day washout period prior to the next sequence. After the third dosing, subjects were monitored to assess delayed drug-related adverse events. Pharmacokinetic parameters were assessed using concentration-time curves for plasma imatinib and its metabolite CGP74588.

RESULTS

Median Tmax was 2.5 h for capsules and tablets. Mean AUC((0-inf)) values were 27,094, 26,081 and 25,464 ng.h/ml for 4 x 100-mg capsules, 4 x 100-mg tablets, and 1 x 400-mg tablets, respectively. Cmax values were 1748, 1638 and 1606 ng/ml, and t(1/2) values were 15.8, 15.9 and 15.7 h. The test/reference ratios for AUC((0-inf)), AUC((0-96) (h)), and C(max) were 0.98, 0.98 and 0.95 for 4 x 100-mg tablets versus 4 x 100-mg capsules, and 0.95, 0.95 and 0.92 for 1 x 400-mg tablet versus 4 x 100-mg capsules. The 95% confidence intervals were fully contained within the interval (0.80, 1.25). Eight mild and one moderate adverse event considered to be drug related were reported. These events showed no clustering by type of dosage form and were of little to no clinical significance.

CONCLUSIONS

Film-coated 100-mg (scored) and 400-mg tablet dose forms of imatinib are bioequivalent to the commercial 100-mg hard-gelatin capsule, and are as safe and well tolerated.

Correlation of Major Cytogenetic Response with a Pharmacogenetic Marker in Chronic Myeloid Leukemia Patients Treated with Imatinib (STI571)

PURPOSE

Imatinib, an inhibitor of the Bcr-Abl tyrosine kinase, is indicated for the treatment of patients with Philadelphia chromosome-positive chronic myeloid leukemia. We examined genotypes from patients enrolled in the International Randomized Study of IFN-alpha versus STI571 in an attempt to identify factors that associate with cytogenetic response.

EXPERIMENTAL DESIGN

Sixty-eight polymorphic loci in 26 genes were examined in a subset of 187 patients (imatinib-treated patients, n = 113; IFN + 1-beta-D-arabinofuranosylcytosine-treated patients, n = 74). Correlations between genotype and major cytogenetic response (MCyR) were examined by Fisher's exact tests. Multivariate and survival analyses were also performed.

RESULTS

A significant association between MCyR and the rs2290573 polymorphism mapped to 15q22.33 was observed in imatinib-treated patients (P = 0.00037, Bonferroni corrected P = 0.025). Individuals with a CC genotype at this locus had a MCyR rate of 52% compared with individuals with a CT or TT genotype that had a MCyR rate of 89% (odds ratio, 6.72; 95% confidence interval, 1.51-29.91). In a multivariate analysis, the rs2290573 polymorphism was significant, whereas Sokal score was not. Time to progression analysis illustrated a significant difference based on genotype for the rs2290573 polymorphism.

CONCLUSIONS

A significant association was identified between the genetic polymorphism rs2290573 and MCyR in imatinib-treated patients. This polymorphism is located in the intronic sequence of a putative gene with a tyrosine kinase domain. Multivariate analysis suggests that an individual's genotype for rs2290573 has more predictive value for MCyR than prognostic variables such as Sokal score. The clinical relevance of these results requires validation in future clinical trials.

Pharmacokinetics and pharmacodynamics of imatinib in a phase I trial with chronic myeloid leukemia patients

PURPOSE

To evaluate the basic pharmacokinetic (PK) characteristics of imatinib mesylate and assess the relationship between the PK and pharmacodynamic (PD) properties of the drug.

PATIENTS AND METHODS

The PK and PD properties of imatinib were investigated during a phase I trial that included 64 adult patients with Philadelphia chromosome-positive leukemias. Patients received imatinib orally once or twice daily. PK parameters of imatinib, derived from the plasma concentration-time curves, were determined. PD response, defined as the WBC after 1 month of treatment with imatinib, was used to develop an efficacy model. A maximum inhibition-effect model was used to describe the relationship between reduction in WBC and drug exposure parameters.

RESULTS

Imatinib exposure was dose proportional after oral administration for the dose range of 25 to 1,000 mg. There was a 1.5- to three-fold drug accumulation after repeated once-daily dosing. Mean plasma trough concentration was 0.57 microg/mL (approximately 1 micromol/L) 24 hours after administration of 350 mg of imatinib at steady-state, which exceeds the 50% inhibitory concentration required to inhibit proliferation of Bcr-Abl-positive leukemic cells. Analysis of PK/PD relationships indicates that the initial hematologic response depends on the administered dose for patients with chronic myeloid leukemia.

CONCLUSION

Drug exposure (area under the concentration-time curve) is dose proportional for the dose range of 25 to 1,000 mg, and there is a 1.5- to three-fold drug accumulation at steady-state after once-daily dosing. Analysis of the relationship between PD (WBC reduction) and PK parameters at steady-state indicates that a dose of 400 mg or greater is required for maximal PD effect.

Effect of rifampicin on the pharmacokinetics of imatinib mesylate (Gleevec, STI571) in healthy subjects

OBJECTIVE

This study was carried out to investigate the influence of CYP3A induction with rifampicin on imatinib (Gleevec) exposure.

METHODS

The study employed a single center, single-sequence design. A group of 14 healthy male and female subjects received imatinib as a single 400 mg oral dose on two occasions: on study day 1 and on study day 15. Rifampicin treatment (600 mg once daily) for CYP4503A induction was initiated on study day 8 and maintained until day 18. Imatinib pharmacokinetics were determined up to 96 h after dosing on day 1 (no induction) and on days 15-18 (during concomitant rifampicin). Plasma concentrations of imatinib and its main metabolite CGP74588 were determined using a LC/MS/MS method. The ratio of 6beta-hydroxycortisol to cortisol excreted in the urine was measured to monitor the induction of CYP3A.

RESULTS

During concomitant rifampicin administration, the mean imatinib C(max), AUC(0-24) and AUC(0- infinity ) decreased by 54% (90% CI: 48-60%), 68% (64-70%) and 74% (71-76%), respectively. The increase in clearance (Cl/f) was 385% (348-426%) during rifampicin treatment. The mean C(max) and AUC(0-24) of the metabolite CGP74588 increased by 88.6% (68.3%-111.4%) and 23.9% (13.5%-35.2%) after rifampicin pretreatment. However, the AUC(0- infinity ) decreased by 11.7% (3.3-19.4%). All subjects demonstrated a marked induction of hepatic microsomal CYP3A analyzed by the excretion ratio of 6beta-hydroxycortisol to cortisol from a mean baseline concentration of 5.6 U to 50.5 U.

CONCLUSION

Concomitant use of imatinib and rifampicin or other potent inducers of CYP4503A may result in subtherapeutic plasma concentrations of imatinib. In patients in whom rifampicin or other CYP3A inducers are prescribed, alternative therapeutic agents with less potential for enzyme induction should be selected.

Pharmacogenomic Analysis of Cytogenetic Response in Chronic Myeloid Leukemia Patients Treated with Imatinib

PURPOSE

To better understand the molecular basis of cytogenetic response in chronic myeloid leukemia patients treated with imatinib, we studied gene expression profiles from a total of 100 patients from a large, multinational Phase III clinical trial (International Randomized Study of IFN-alpha versus STI571).

EXPERIMENTAL DESIGN

Gene expression data for >12,000 genes were generated from whole blood samples collected at baseline (before imatinib treatment) using Affymetrix oligonucleotide microarrays. Cytogenetic response was determined based on the percentage of Ph(+) cells from bone marrow following a median of 13 months of treatment.

RESULTS

A genomic profile of response was developed using a subset of individuals that exhibited the greatest divergence in cytogenetic response; those with complete response (0% Ph(+) cells; n = 53) and those with minimal or no response (>65% Ph(+) cells; n = 13). A total of 55 genes was identified that were differentially expressed between these two groups. Using a "leave-one-out" strategy, we identified the optimum 31 genes from this list to use as our genomic profile of response. Using this genomic profile, we were able to distinguish between individuals that achieved major cytogenetic response (0-35% Ph(+) cells) and those that did not, with a sensitivity of 93.4% (71 of 76 patients), specificity of 58.3% (14 of 24 patients), positive predictive value of 87.7%, and negative predictive value of 73.7%.

CONCLUSIONS

Interestingly, many of the genes identified appear to be strongly related to reported mechanisms of BCR-ABL transformation and warrant additional research as potential drug targets. The validity and clinical implications of these results should be explored in future studies.

Effects of imatinib mesylate (STI571, Glivec) on the pharmacokinetics of simvastatin, a cytochrome p450 3A4 substrate, in patients with chronic myeloid leukaemia

The inhibition by imatinib of the cytochrome P450 3A4 isoenzyme may reduce the CYP3A4-mediated metabolic clearance of clinically important coadministered drugs. The main purpose of this study was to evaluate the effect of the coadministration of imatinib on the pharmacokinetics of simvastatin, a probe CYP3A4 substrate. In total, 20 patients with chronic myeloid leukaemia received an oral dose of 40 mg of simvastatin on study day 1. On study days 2–7, each patient received 400 mg of imatinib once daily orally and on study day 8, 400 mg imatinib together with 40 mg of simvastatin was given. Blood levels of simvastatin were measured predose and for 24 h postdose on study days 1 and 8. Two additional blood samples were taken for imatinib pharmacokinetic (PK) assessment on day 8 before, and 24 h after, imatinib administration. Imatinib increased the mean maximum concentration (C_max) value of simvastatin two-fold and the area under concentration–time curve (AUC _(0–inf)) value 3.5-fold (P<0.001) compared with simvastatin alone. There was a statistically significant decrease in total-body clearance of drug from the plasma (CL/F) with a mean reduction of 70% for simvastatin (P<0.001): the mean half-life of simvastatin was prolonged from 1.4–2.7 h when given together with imatinib. No changes in imatinib PK parameters were found when given concomitantly with simvastatin. In conclusion, the coadministration of imatinib at steady state with 40 mg simvastatin increases the exposure (C_max and AUCs) of simvastatin significantly (P<0.001) by two-three-fold. Caution is therefore required when administering imatinib with CYP3A4 substrates with a narrow therapeutic window. The coadministration of simvastatin with imatinib (400 mg) was well tolerated and no major safety findings were reported in this study.

Imatinib: a targeted clinical drug development

Imatinib (Gleevec) (formerly STI571) is an orally bioavailable rationally developed inhibitor of the tyrosine kinases Bcr-Abl, Kit, and platelet-derived growth factor receptor (PDGFR). In 4 years of clinical development, more than 12,000 patients have been treated in the clinical development program. Imatinib was first shown to be highly effective in the treatment of all stages of chronic myelogenous leukemia (CML). Moreover, preliminary results of a randomized study have demonstrated superior efficacy and safety of first-line imatinib therapy compared with a combination of interferon and cytarabine. Imatinib has also been shown to be the only effective drug therapy in the treatment of patients with metastatic gastrointestinal stromal tumors expressing the stem cell factor (SCF) receptor Kit. This review outlines the successive steps in the clinical development of this new, targeted anticancer agent.

Imatinib compared with interferon and low-dose cytarabine for newly diagnosed chronic-phase chronic myeloid leukemia

BACKGROUND

Imatinib, a selective inhibitor of the BCR-ABL tyrosine kinase, produces high response rates in patients with chronic-phase chronic myeloid leukemia (CML) who have had no response to interferon alfa. We compared the efficacy of imatinib with that of interferon alfa combined with low-dose cytarabine in newly diagnosed chronic-phase CML.

METHODS

We randomly assigned 1106 patients to receive imatinib (553 patients) or interferon alfa plus low-dose cytarabine (553 patients). Crossover to the alternative group was allowed if stringent criteria defining treatment failure or intolerance were met. Patients were evaluated for hematologic and cytogenetic responses, toxic effects, and rates of progression.

RESULTS

After a median follow-up of 19 months, the estimated rate of a major cytogenetic response (0 to 35 percent of cells in metaphase positive for the Philadelphia chromosome) at 18 months was 87.1 percent (95 percent confidence interval, 84.1 to 90.0) in the imatinib group and 34.7 percent (95 percent confidence interval, 29.3 to 40.0) in the group given interferon alfa plus cytarabine (P<0.001). The estimated rates of complete cytogenetic response were 76.2 percent (95 percent confidence interval, 72.5 to 79.9) and 14.5 percent (95 percent confidence interval, 10.5 to 18.5), respectively (P<0.001). At 18 months, the estimated rate of freedom from progression to accelerated-phase or blast-crisis CML was 96.7 percent in the imatinib group and 91.5 percent in the combination-therapy group (P<0.001). Imatinib was better tolerated than combination therapy.

CONCLUSIONS

In terms of hematologic and cytogenetic responses, tolerability, and the likelihood of progression to accelerated-phase or blast-crisis CML, imatinib was superior to interferon alfa plus low-dose cytarabine as first-line therapy in newly diagnosed chronic-phase CML.

Quantitative monitoring of BCR/ABL transcript during STI-571 therapy

PCR for the BCR/ABL fusion transcript provides a highly sensitive and specific method for detecting minimal residual disease in patients with chronic myeloid leukemia (CML). We sought to determine if quantitative PCR measurement of peripheral blood BCR/ABL transcript can be used to monitor response in CML patients with clinically evident disease while receiving the protein tyrosine kinase inhibitor STI-571. Serial bone marrow cytogenetics and peripheral blood BCR/ABL mRNA levels were measured in 17 patients [9 with chronic phase (CP) and 8 with accelerated phase or blast crisis (AP/BC)] during 1 year of treatment. Overall, quantitative PCR BCR/ABL transcript level decreased by a median of 0.9 log during the first 3 months, and by 1.6 logs by 12 months. Among cytogenetic responders (6 CP and 2 AP/BC), median BCR/ABL copy number was 0.9 and 2.1 logs lower than baseline after 3 and 12 months of treatment, respectively. No patient became PCR-negative for BCR/ABL. Among cytogenetic non-responders, BCR/ABL transcript level decreased by 0.4 logs after 3 months, with no subsequent reductions. At study entry, BCR/ABL expression in cytogenetic responders and non-responders was similar. However, BCR/ABL expression became significantly different 3 months after treatment (p = 0.02), and increasingly different with continued therapy (p = 0.04, 0.005, 0.0008 at 6, 9 and 12 months, respectively). Our results demonstrate that PBMC BCR/ABL mRNA levels correlate well with response to STI-571. This non-invasive, rapid and sensitive PCR-based assay can be used to monitor response to STI-571.

A phase 2 study of imatinib in patients with relapsed or refractory Philadelphia chromosome-positive acute lymphoid leukemias

The translocation (9;22) gives rise to the p190(Bcr-Abl) and p210(Bcr-Abl) tyrosine kinase proteins, considered sufficient for leukemic transformation. Philadelphia-positive (Ph(+)) acute leukemia patients failing to respond to initial induction therapy have a poor prognosis with few effective treatment options. Imatinib is an orally administered, potent inhibitor of the Bcr-Abl tyrosine kinase. We conducted a clinical trial in 56 patients with relapsed or refractory Ph(+) acute lymphoblastic leukemia (ALL; 48 patients) or chronic myelogenous leukemia in lymphoid blast crisis (LyBC; 8 patients). Imatinib was given once daily at 400 mg or 600 mg. Imatinib induced complete hematologic responses (CHRs) and complete marrow responses (marrow-CRs) in 29% of ALL patients (CHR, 19%; marrow-CR, 10%), which were sustained for at least 4 weeks in 6% of patients. Median estimated time to progression and overall survival for ALL patients were 2.2 and 4.9 months, respectively. CHRs were reported for 3 (38%) of the patients with LyBC (one sustained CHR). Grade 3 or 4 treatment-related nonhematologic toxicity was reported for 9% of patients; none of the patients discontinued therapy because of nonhematologic adverse reactions. Grade 4 neutropenia and thrombocytopenia occurred in 54% and 27% of patients, respectively. Imatinib therapy resulted in a clinically relevant hematologic response rate in relapsed or refractory Ph(+) acute lymphoid leukemia patients, but development of resistance and subsequent disease progression were rapid. Further studies are warranted to test the effects of imatinib in combination with other agents and to define the mechanisms of resistance to imatinib.

The impact of clonal evolution on response to imatinib mesylate (STI571) in accelerated phase CML

In chronic myelogenous leukemia (CML), the development of chromosomal abnormalities in addition to the Philadelphia chromosome (clonal evolution) is considered by many to be a feature of accelerated phase (AP). Imatinib mesylate (STI571), a selective inhibitor of the Bcr-Abl tyrosine kinase, has significant activity in AP CML. As clonal evolution could allow Bcr-Abl independent proliferation, we analyzed its impact on the outcome of 71 AP patients treated with 600 mg of imatinib mesylate. Fifteen patients had clonal evolution alone (AP-CE), 32 had AP features but no evidence of clonal evolution (HEM-AP), and 24 had AP features plus clonal evolution (HEM-AP + CE). Of the AP-CE patients, 73% had a major cytogenetic response, compared with 31% of the HEM-AP patients (P =.043) and 12.5% of the HEM-AP + CE patients (P =.007). Complete cytogenetic responses were seen in 60% of AP-CE patients, compared with 31% of HEM-AP patients (P =.19) and 8% of HEM-AP + CE patients (P <.001). With mean follow-up of 11.2 months, 35% of all patients failed treatment. The lowest estimated rate of treatment failure at 1 year, 0%, was seen in AP-CE patients, compared with rates of 31% for HEM-AP patients and 69% for HEM-AP + CE patients (P =.0004). After 1 year, 100% of AP-CE patients were still alive, compared with 85% of HEM-AP patients and 67.5% of HEM-AP + CE patients (P =.01). In conclusion, in patients with clonal evolution as the sole criterion of disease acceleration, good responses to imatinib are still possible. Once patients have other signs of acceleration, clonal evolution predicts lower response rates and a shorter time to treatment failure.

Imatinib: the first 3 years

Imatinib (Glivec, formerly STI571, Novartis Pharma AG, Basel, Switzerland) potently inhibits several protein tyrosine kinases, including Bcr-Abl, Kit, and the platelet-derived growth factor receptor. Phase I and II studies demonstrated that orally administered imatinib is highly effective and well tolerated in all phases of chronic myeloid leukemia (CML) at doses ranging from 400 to 600 mg. Importantly, preliminary evidence suggests that patients with advanced CML achieving hematologic or major cytogenetic responses to imatinib may have longer survival than those without such responses, whereas chronic phase patients who respond to treatment may have longer times to disease progression. Ongoing and planned studies are focused on optimizing CML treatment with imatinib, evaluating imatinib-based combination therapy, defining additional therapeutic targets and exploring the use of imatinib in children. In particular, results from several combination phase I studies are expected shortly, including an evaluation of combination imatinib-interferon-alpha therapy and imatinib-cytarabine in chronic phase CML, and a phase I study of single-agent imatinib in children with Philadelphia chromosome-positive leukemia is ongoing. A large phase III trial comparing imatinib with standard inferferon alfa plus cytarabine in first-line CML treatment is also ongoing.

Efficacy and safety of imatinib mesylate in advanced gastrointestinal stromal tumors

BACKGROUND

Constitutive activation of KIT receptor tyrosine kinase is critical in the pathogenesis of gastrointestinal stromal tumors. Imatinib mesylate, a selective tyrosine kinase inhibitor, has been shown in preclinical models and preliminary clinical studies to have activity against such tumors.

METHODS

We conducted an open-label, randomized, multicenter trial to evaluate the activity of imatinib in patients with advanced gastrointestinal stromal tumor. We assessed antitumor response and the safety and tolerability of the drug. Pharmacokinetics were assessed in a subgroup of patients.

RESULTS

A total of 147 patients were randomly assigned to receive 400 mg or 600 mg of imatinib daily. Overall, 79 patients (53.7 percent) had a partial response, 41 patients (27.9 percent) had stable disease, and for technical reasons, response could not be evaluated in 7 patients (4.8 percent). No patient had a complete response to the treatment. The median duration of response had not been reached after a median follow-up of 24 weeks after the onset of response. Early resistance to imatinib was noted in 20 patients (13.6 percent). Therapy was well tolerated, although mild-to-moderate edema, diarrhea, and fatigue were common. Gastrointestinal or intraabdominal hemorrhage occurred in approximately 5 percent of patients. There were no significant differences in toxic effects or response between the two doses. Imatinib was well absorbed, with pharmacokinetics similar to those reported in patients with chronic myeloid leukemia.

CONCLUSIONS

Imatinib induced a sustained objective response in more than half of patients with an advanced unresectable or metastatic gastrointestinal stromal tumor. Inhibition of the KIT signal-transduction pathway is a promising treatment for advanced gastrointestinal stromal tumors, which resist conventional chemotherapy.

Chronic myelogenous leukemia

The treatment recommendations for chronic myelogenous leukemia (CML) are evolving rapidly. In the past year, pegylated interferon and STI571 (Gleevec, imatinib mesylate), a Bcr-Abl tyrosine kinase inhibitor, have become commercially available and non-myeloablative stem cell transplants continue to be refined. Clinicians and patients face a bewildering array of treatment options for CML. In this article Dr. Sawyer reviews the clinical results with STI571 and ongoing investigations into mechanisms of resistance to STI571. Given the newness of STI571, a practical overview on the administration of STI571 is presented by Drs. Druker and Ford, focusing on aspects such as optimal dose, management of common side effects, and potential drug interactions. The most recent data on interferon-based regimens are reviewed by Dr. Baccarani in the third section. In the last section Dr. Goldman presents recent results of allogeneic stem cell transplants, including the reduced intensity conditioning regimens. Lastly, the proposed place of each of these treatments in the management of CML patients is addressed to assist in deciding amongst treatment options for CML patients.

Treatment of philadelphia chromosome-positive, accelerated-phase chronic myelogenous leukemia with imatinib mesylate

PURPOSE

Imatinib mesylate, a specific Bcr-Abl tyrosine kinase inhibitor, has shown encouraging activity in chronic myelogenous leukemia (CML).

EXPERIMENTAL DESIGN

We treated 237 patients (median age, 50 years; age range, 18-82 years) with Philadelphia chromosome (Ph)-positive accelerated-phase CML with oral imatinib mesylate at daily doses of 400 mg (26 patients) or 600 mg (211 patients) and evaluated response and survival characteristics in univariate and multivariate analyses.

RESULTS

Among the 200 patients with accelerated-phase CML for whom follow-up was 3 months or more, rates of complete and partial hematological response were 80% and 10%. Cytogenetic responses were evident in 90 patients [45%; complete response in 47 patients (24%) and partial response (Ph 1-34%) in 21 patients (11%)]. The estimated 18-month survival rate was 73%. The estimated complete hematological response rate at 18 months was 68%; that for cytogenetic response was 82%. In multivariate analyses, a diagnosis-to-treatment interval of 3 years or more, splenomegaly, and peripheral blasts predicted poor major cytogenetic response; age >60 years, marrow basophilia, and clonal evolution predicted poor survival. The 600-mg drug dose was associated with better cytogenetic response and survival in univariate analysis (P < 0.01) but not in multivariate analysis. Landmark analysis showed that achieving a cytogenetic response at 3 months or a major cytogenetic response (Ph < 35%) at 6 months was associated with better long-term survival. Seven of 15 patients who were in a second chronic phase achieved major cytogenetic response. The incidence of severe nonhematological toxic effects was 23%; drug discontinuation for severe toxicity was needed in 3% of patients.

CONCLUSIONS

Imatinib mesylate was active against Ph-positive, accelerated-phase CML, and the prognostic factors identified in this study could aid in tailoring treatment strategies to specific risk groups.

Imatinib mesylate for Philadelphia chromosome-positive, chronic-phase myeloid leukemia after failure of interferon-alpha: follow-up results

We treated 261 patients with Philadelphia chromosome (Ph)-positive chronic myeloid leukemia (CML) in chronic phase after failure of IFN-alpha with the Bcr-Abl tyrosine kinase inhibitor imatinib mesylate (400 mg/day given p.o.) and analyzed hematological and cytogenetic responses, long-term prognosis, factors associated with achievement of major cytogenetic response and survival, and comparative survival in similar patients treated with other regimens. Median patient age was 55 years; 34% were 60 years or older, and median chronic-phase duration was 33 months. Overall, 94% achieved a complete hematological response, and 71% had a cytogenetic response [major (Ph+ cells <35%) in 62% and complete in 45%]. At a median follow-up of 17 months, 241 patients (92%) were still taking imatinib mesylate; estimated 18-month freedom from progression and survival rates were 93 and 96%. Multivariate analysis of factors associated with major cytogenetic response identified long chronic phase, marrow basophilia, high percentage of Ph+ cells before therapy, and prior hematological resistance to IFN-alpha as being adverse factors. This model was used to generate good-, intermediate- and poor-risk subgroups who had estimated major cytogenetic response rates of 93, 53, and 34%, respectively. Univariate analysis in terms of survival identified leukocytosis, high percentages of peripheral and marrow blasts, marrow basophilia, and the presence of cytogenetic clonal evolution as being adverse factors. Achieving a cytogenetic response at 3 or 6 months of therapy was associated with prolonged survival. In a subset analysis, survival rates among 161 patients with Ph-positive CML after hematological or cytogenetic failure after IFN-alpha who had been treated with imatinib mesylate were better than those for similar patients treated previously with other regimens. In summary, imatinib mesylate is highly effective in chronic-phase CML after IFN-alpha failure. We identified pretreatment and treatment-associated factors that were associated with higher major cytogenetic response rates and with improved survival.

A phase I and pharmacokinetic study of SAM486A, a novel polyamine biosynthesis inhibitor, administered on a daily-times-five every-three-week schedule in patients with Advanced solid malignancies

PURPOSE

SAM486A is a novel inhibitor of the polyamine biosynthetic enzyme S-adenosylmethionine decarboxylase (SAMDC). This study was performed to characterize the toxicity profile and the pharmacological behavior and to determine the maximum tolerated dose (MTD) of SAM486A administered by a 1-h i.v. infusion daily for 5 days every 3 weeks in patients with advanced cancer.

EXPERIMENTAL DESIGN

Twenty-three patients received 46 cycles of SAM486A at dose levels ranging from 3.6 to 202.8 mg/m(2)/day. SAM486A plasma concentrations were measured during the first cycle for pharmacokinetic and pharmacodynamic evaluations. Paired tumor biopsy specimens pre- and posttreatment were obtained in 1 patient to assess the impact of SAM486A on intratumoral enzymes and metabolites involved in the polyamine biosynthetic pathway.

RESULTS

The dose-limiting toxicity of SAM486A on this schedule was myelosuppression. Nonhematological toxicities, including nausea, vomiting, anorexia, and fatigue, were mild to moderate in severity. The MTD of SAM486A was 102.4 mg/m(2)/day. Pharmacokinetic analyses demonstrated a rapid initial decrease in plasma drug concentrations at the end of infusion, followed by a long terminal elimination phase with a mean (+/- SD) terminal elimination half-life of 65.4 +/- 55.6 h. Dose and area under the concentration-time curve correlated with the appearance of grade 4 neutropenia with correlation coefficients of 0.70 and 0.69, respectively. Analysis of paired tumor biopsy specimens taken before and after SAM486A treatment in 1 patient with metastatic melanoma revealed decreased SAMDC activity, increased ornithine decarboxylase activity, increased levels of putrescine, and depleted levels of decarboxylated S-adenosylmethionine and spermine, all of which are consistent with the proposed mode of action of SAM486A.

CONCLUSIONS

SAM486A was well tolerated on this schedule of administration with the MTD established at 102.4 mg/m(2)/day. Neutropenia was dose-limiting and correlated with dose and area under the concentration-time curve. Pharmacodynamic assessment of tumoral tissues in 1 study patient demonstrated changes in the levels of polyamines and their biosynthetic enzymes consistent with SAMDC inhibition.

Glivec (STI571, imatinib), a rationally developed, targeted anticancer drug

In the early 1980s, it became apparent that the work of pioneers such as Robert Weinberg, Mariano Barbacid and many others in identifying cancer-causing genes in humans was opening the door to a new era in anticancer research. Motivated by this, and by dissatisfaction with the limited efficacy and tolerability of available anticancer modalities, a drug discovery programme was initiated with the aim of rationally developing targeted anticancer therapies. Here, we describe how this programme led to the discovery and continuing development of Glivec (Gleevec in the United States), the first selective tyrosine-kinase inhibitor to be approved for the treatment of a cancer.

Dose-finding study of valspodar (PSC 833) with daunorubicin and cytarabine to reverse multidrug resistance in elderly patients with previously untreated acute myeloid leukemia

INTRODUCTION

This trial was designed to determine the maximum tolerated dose of intravenous daunorubicin (DNR) in combination with valspodar and to test the feasibility of P-glycoprotein modulation using valspodar in elderly patients with previously untreated acute myelogenous leukemia receiving standard induction chemotherapy.

METHODS

Patients > or =60 years of age with previously untreated AML received valspodar (10 mg/kg/24 h by continuous intravenous infusion [CIV] on days 1-4 with a 2-mg/kg loading dose on day 1) in conjunction with two cycles of induction chemotherapy consisting of cytarabine (200 mg/m(2) CIV on days 1-7), and DNR (35 mg/m(2) [cohort 1] or 45 mg/m(2) [cohort 2] on days 1-3, intravenous bolus). Patients were assessed for dose-limiting toxicities (DLT), response rate, event-free and overall survival, and pharmacokinetics of valspodar and DNR.

RESULTS

Valspodar was well tolerated at the lower DNR dose level (ie, 35 mg/m(2)) resulting in a 21% rate of DLT and only three toxic deaths. Treatment-related mortality was unacceptably high at the 45 mg/m(2) DNR dose level. The complete response rate was 49% overall and similar in both cohorts. The median overall survival of patients was 333 days in cohort 1 compared to 98 days in cohort 2. At baseline, 70% of assessable patients were P-glycoprotein positive.

CONCLUSION

Substantial inhibition of P-glycoprotein activity can be achieved in this patient population at clinically tolerable doses of valspodar and DNR. The maximum tolerated dose of DNR was established as 35 mg/m(2). This regimen is being further evaluated in phase III trials.

Imatinib induces hematologic and cytogenetic responses in patients with chronic myelogenous leukemia in myeloid blast crisis: results of a phase II study

Blast crisis is the most advanced stage of chronic myelogenous leukemia (CML) and is highly refractory to therapy. CML is caused by expression of the chimeric BCR-ABL tyrosine kinase oncogene, the product of the t(9;22) Philadelphia translocation. Imatinib (Glivec, formerly STI571) is a rationally developed, orally administered inhibitor of the Bcr-Abl tyrosine kinase. A total of 260 patients with CML were enrolled in a phase II trial, of whom 229 had a confirmed diagnosis of CML in blast crisis. Patients were treated with imatinib in daily oral doses of 400 mg or 600 mg. Imatinib induced hematologic responses in 52% of patients and sustained hematologic responses lasting at least 4 weeks in 31% of patients, including complete hematologic responses in 8%. For patients with a sustained response, the estimated median response duration was 10 months. Imatinib induced major cytogenetic responses in 16% of patients, with 7% of the responses being complete. Median survival time was 6.9 months. Nonhematologic adverse reactions were frequent but generally mild or moderate. Episodes of severe cytopenia were also frequent and were attributable to the underlying condition and treatment with imatinib. Drug-related adverse events led to discontinuation of therapy in 5% of patients, most often because of cytopenia, skin disorders, or gastrointestinal reactions. These results demonstrate that imatinib has substantial activity and a favorable safety profile when used as a single agent in patients with CML in blast crisis. Additional clinical studies are warranted to explore the efficacy and feasibility of imatinib used in combination with other antileukemic drugs.

Transient response to imatinib mesylate (STI571) in a patient with the ETV6-ABL t(9;12) translocation

We report the transient response of a patient with the ETV6-ABL fusion gene to imatinib mesylate (STI571). A 38-year-old man was referred with an erroneous diagnosis of Philadelphia-positive chronic myeloid leukemia in blastic transformation for treatment with the ABL tyrosine kinase inhibitor, STI571. Further investigation indicated that the patient in fact had acute myeloid leukemia; no evidence of the Philadelphia translocation or BCR-ABL was found using fluorescence in situ hybridization (FISH) or reverse transcription-polymerase chain reaction. Detailed FISH analysis identified a cryptic t(9;12) translocation, and molecular studies confirmed the presence of the ETV6-ABL fusion transcript. Because the patient was gravely ill at presentation, treatment was commenced immediately with STI571 monotherapy, resulting in considerable initial improvement. However within 10 days the patient's condition again deteriorated, and he required conventional chemotherapy. This case has implications for the design of future studies using STI571 in leukemias involving ABL-encoded fusion proteins other than BCR-ABL.

Imatinib induces durable hematologic and cytogenetic responses in patients with accelerated phase chronic myeloid leukemia: results of a phase 2 study

Chronic myelogenous leukemia (CML) is caused by expression of the BCR-ABL tyrosine kinase oncogene, the product of the t(9;22) Philadelphia translocation. Patients with CML in accelerated phase have rapidly progressive disease and are characteristically unresponsive to existing therapies. Imatinib (formerly STI571) is a rationally developed, orally administered inhibitor of the Bcr-Abl kinase. A total of 235 CML patients were enrolled in this study, of whom 181 had a confirmed diagnosis of accelerated phase. Patients were treated with imatinib at 400 or 600 mg/d and were evaluated for hematologic and cytogenetic response, time to progression, survival, and toxicity. Imatinib induced hematologic response in 82% of patients and sustained hematologic responses lasting at least 4 weeks in 69% (complete in 34%). The rate of major cytogenetic response was 24% (complete in 17%). Estimated 12-month progression-free and overall survival rates were 59% and 74%, respectively. Nonhematologic toxicity was usually mild or moderate, and hematologic toxicity was manageable. In comparison to 400 mg, imatinib doses of 600 mg/d led to more cytogenetic responses (28% compared to 16%), longer duration of response (79% compared to 57% at 12 months), time to disease progression (67% compared to 44% at 12 months), and overall survival (78% compared to 65% at 12 months), with no clinically relevant increase in toxicity. Orally administered imatinib is an effective and well-tolerated treatment for patients with CML in accelerated phase. A daily dose of 600 mg is more effective than 400 mg, with similar toxicity.

Hematologic and cytogenetic responses to imatinib mesylate in chronic myelogenous leukemia

BACKGROUND

Chronic myelogenous leukemia (CML) is caused by the BCR-ABL tyrosine kinase, the product of the Philadelphia chromosome. Imatinib mesylate, formerly STI571, is a selective inhibitor of this kinase.

METHODS

A total of 532 patients with late--chronic-phase CML in whom previous therapy with interferon alfa had failed were treated with 400 mg of oral imatinib daily. Patients were evaluated for cytogenetic and hematologic responses. Time to progression, survival, and toxic effects were also evaluated.

RESULTS

Imatinib induced major cytogenetic responses in 60 percent of the 454 patients with confirmed chronic-phase CML and complete hematologic responses in 95 percent. After a median follow-up of 18 months, CML had not progressed to the accelerated or blast phases in an estimated 89 percent of patients, and 95 percent of the patients were alive. Grade 3 or 4 nonhematologic toxic effects were infrequent, and hematologic toxic effects were manageable. Only 2 percent of patients discontinued treatment because of drug-related adverse events, and no treatment-related deaths occurred.

CONCLUSIONS

Imatinib induced high rates of cytogenetic and hematologic responses in patients with chronic-phase CML in whom previous interferon therapy had failed.

Randomized, controlled, dose-range study of Ro 25-8315 given before and after a high-dose combination chemotherapy regimen in patients with metastatic or recurrent breast cancer patients

PURPOSE

To evaluate the safety, pharmacokinetics, and efficacy of three different dose levels of pegylated granulocyte colony-stimulating factor (Ro 25-8315) on progenitor cell mobilization and hematologic recovery in cancer patients.

PATIENTS AND METHODS

Breast cancer patients (n = 36) were randomly assigned to receive before (part I) and after (part II) chemotherapy either a single-dose injection of Ro 25-8315 (20 microg/kg, n = 9; 60 microg/kg, n = 9; 100 microg/kg, n = 10) or a standard daily dose of filgrastim (part I, 10 microg/kg/d; part II, 5 microg/kg/d) (control group, n = 8).

RESULTS

Overall, Ro 25-8315 was well tolerated. In part I, more progenitor cell mobilization was observed with Ro 25-8315 100 microg/kg. The peak of circulating CD34(+) cells was obtained at day +5 in the four groups, and the absolute neutrophil count (ANC) returned to less than 20 x 10(9)/L by day +15. In part II, high levels of circulating CD34(+) cells (> 20 cells/microL) were obtained in all four groups. The chemotherapy-induced neutropenia (< 1 x 10(9)/L) was similar in the four groups. Ro 25-8315 100 microg/kg was more effective than filgrastim in reducing the number of patients with an ANC less than 0.5 x 10(9)/L on day +12 after chemotherapy.

CONCLUSION

A single injection of Ro 25-8315 100 microg/kg might be the optimal dose for steady-state peripheral-blood progenitor cell mobilization. A single injection of 20, 60, or 100 microg/kg could be as efficient as daily administration of filgrastim to correct chemotherapy-induced cytopenia. The optimal dose of Ro 25-8315 should be determined according to the planned chemotherapy regimen.

Efficacy and safety of a specific inhibitor of the BCR-ABL tyrosine kinase in chronic myeloid leukemia

BACKGROUND

BCR-ABL is a constitutively activated tyrosine kinase that causes chronic myeloid leukemia (CML). Since tyrosine kinase activity is essential to the transforming function of BCR-ABL, an inhibitor of the kinase could be an effective treatment for CML.

METHODS

We conducted a phase 1, dose-escalating trial of STI571 (formerly known as CGP 57148B), a specific inhibitor of the BCR-ABL tyrosine kinase. STI571 was administered orally to 83 patients with CML in the chronic phase in whom treatment with interferon alfa had failed. Patients were successively assigned to 1 of 14 doses ranging from 25 to 1000 mg per day.

RESULTS

Adverse effects of STI571 were minimal; the most common were nausea, myalgias, edema, and diarrhea. A maximal tolerated dose was not identified. Complete hematologic responses were observed in 53 of 54 patients treated with daily doses of 300 mg or more and typically occurred in the first four weeks of therapy. Of the 54 patients treated with doses of 300 mg or more, cytogenetic responses occurred in 29, including 17 (31 percent of the 54 patients who received this dose) with major responses (0 to 35 percent of cells in metaphase positive for the Philadelphia chromosome); 7 of these patients had complete cytogenetic remissions.

CONCLUSIONS

STI571 is well tolerated and has significant antileukemic activity in patients with CML in whom treatment with interferon alfa had failed. Our results provide evidence of the essential role of BCR-ABL tyrosine kinase activity in CML and demonstrate the potential for the development of anticancer drugs based on the specific molecular abnormality present in a human cancer.

Activity of a specific inhibitor of the BCR-ABL tyrosine kinase in the blast crisis of chronic myeloid leukemia and acute lymphoblastic leukemia with the Philadelphia chromosome

BACKGROUND

BCR-ABL, a constitutively activated tyrosine kinase, is the product of the Philadelphia chromosome. This enzyme is present in virtually all cases of chronic myeloid leukemia (CML) throughout the course of the disease, and in 20 percent of cases of acute lymphoblastic leukemia (ALL). On the basis of the substantial activity of the inhibitor in patients in the chronic phase, we evaluated STI571 (formerly known as CGP 57148B), a specific inhibitor of the BCR-ABL tyrosine kinase, in patients who had CML in blast crisis and in patients with ALL who had the Ph chromosome.

METHODS

In this dose-escalating pilot study, 58 patients were treated with STI571; 38 patients had a myeloid blast crisis and 20 had ALL or a lymphoid blast crisis. Treatment was given orally at daily doses ranging from 300 to 1000 mg.

RESULTS

Responses occurred in 21 of 38 patients (55 percent) with a myeloid-blast-crisis phenotype; 4 of these 21 patients had a complete hematologic response. Of 20 patients with a lymphoid blast crisis or ALL, 14 (70 percent) had a response, including 4 who had complete responses. Seven patients with a myeloid blast crisis continue to receive treatment and remain in remission from 101 to 349 days after starting the treatment. All but one patient with a lymphoid blast crisis or ALL has relapsed. The most frequent adverse effects were nausea, vomiting, edema, thrombocytopenia, and neutropenia.

CONCLUSIONS

The BCR-ABL tyrosine kinase inhibitor STI571 is well tolerated and has substantial activity in the blast crises of CML and in Ph-positive ALL.

Pharmacodynamics and pharmacokinetics of single doses of subcutaneous pegylated human G-CSF mutant (Ro 25-8315) in healthy volunteers: comparison with single and multiple daily doses of filgrastim

Ro 25-8315 is produced by conjugation of rhG-CSF mutant with polyethylene glycol (PEG). The purpose of this study was to examine the pharmacodynamics and pharmacokinetics of Ro 25-8315 in comparison with Filgrastim (rhG-CSF). Subjects received single subcutaneous doses of Ro 25-8315 ranging from 10 to 150 microg/kg using a double-blind, randomized, placebo-controlled design. Filgrastim was administered as a single dose (5 or 10 microg/kg) and, following a 14-day washout period, daily for 7 days. Ro 25-8315 increased absolute neutrophil count (ANC) by 6- to 8-fold and CD34+ cell count more than 30-fold at the highest doses tested. Single doses (60-150 microg/kg) of Ro 25-8315 and multiple doses of Filgrastim had similar effects on ANC and CD34+, although Ro 25-8315 had a greater effect on CFU-GM. The pharmacokinetics of Ro 25-8315 were dose-dependent, with peak concentrations and area under the serum concentration-time curve (AUC) increasing 100-fold over the range of doses studied. Time to reach peak concentration (T(max)) and half-life of Ro 25-8315 averaged 20-30 hr at all doses, approximately three times longer than with Filgrastim. Adverse events were not serious and occurred with similar frequency with both products. Pegylation of rhG-CSF mutant results in more desirable pharmacokinetic properties and a longer duration of action with effective increases in ANC and measures of peripheral blood progenitor cell mobilization for at least 1 week.

A phase I study of a new polyamine biosynthesis inhibitor, SAM486A, in cancer patients with solid tumours

Because tumour cell proliferation is highly dependent upon up-regulation of de-novo polyamine synthesis, inhibition of the polyamine synthesis pathway represents a potential target for anticancer therapy. SAM486A (CGP 48664) is a new inhibitor of the polyamine biosynthetic enzyme S-adenosylmethionine decarboxylase (SAMDC), more potent and specific than the first-generation SAMDC inhibitor methylglyoxal (bis) guanylhydrazone (MGBG). Preclinical testing confirmed promising antiproliferative activity. In this phase I study, SAM486A was given 4-weekly as a 120 h infusion. 39 adult cancer patients were enrolled with advanced/refractory disease not amenable to established treatments, PS </= 2, adequate marrow, liver, renal and cardiac function. Doses were escalated in 100% increments without toxicity in 24 pts from 3 mg m(-2)cycle(-1)up to 400 mg m(-2)cycle(-1). At 550 and 700 mg m(-2)cycle(-1)reversible dose-limiting neutropenia occurred. Other toxicities included mild fatigue, nausea and vomiting. No objective remission was seen. Pharmakokinetic analysis showed a terminal half-life of approximately 2 days. AUC and Cmax were related to dose; neutropenia correlated with AUC. The recommended dose for further phase II studies on this schedule is 400 mg m(-2)cycle(-1).

Phase I and pharmacological study of weekly administration of the polyamine synthesis inhibitor SAM 486A (CGP 48 664) in patients with solid tumors. European Organization for Research and Treatment of Cancer Early Clinical Studies Group

A single-agent dose-escalating Phase I and pharmacological study of the polyamine synthesis inhibitor SAM 486A was performed. A dosing regimen of four weekly infusions followed by 2 weeks off therapy was studied. Fifty patients were entered into the study. Dose levels studied were 1.25, 2.5, 5, 8, 16, 32, 48, 70, 110, 170, 270, and 325 mg/m2/week. Pharmacokinetic sampling was done on day 1, and trough samples were taken weekly during the first treatment cycle. Pharmacodynamic sampling was done on days 1 and 22. At 325 mg/m2/week, dose-limiting toxicity was seen (one patient each with grade 4 febrile neutropenia, grade 3 neurotoxicity, and grade 3 hypotension with syncope and T-wave inversions on electrocardiogram). The recommended dose for further testing was set at 270 mg/m2/week. Infusion time was increased from 10 to 180 min due to facial paresthesias and flushing and somnolence. Drug exposure increased linearly with dose. Mean +/- SD t1,2 at 70-325 mg/m2 doses was 61.4+/-26.2 h, with a large volume of distribution at steady state. In peripheral blood leukocytes, a clear relationship between dose and inhibitory effect on S-adenosylmethionine decarboxylase or changes in intracellular polyamine pools was not recorded. SAM 486A can be administered safely using a dosing regimen of four weekly infusions followed by 2 weeks off therapy. The recommended dose for Phase II studies using this regimen is 270 mg/m2/week.

Population pharmacokinetics/toxicodynamics (PK/TD) relationship of SAM486A in phase I studies in patients with advanced cancers

SAM486A (previously termed CGP 48664), a potent inhibitor of S-adenosylmethionine decarboxylase, is under clinical development for the treatment of advanced refractory malignancies. Hematological toxicity manifested by dose-dependent neutropenia has been observed in phase I studies. Population methods were used to investigate pharmacokinetics (PK) as a prognostic factor for safety end point (hematological toxicity) in patients with advanced cancers. SAM486A plasma concentrations and neutrophil counts were collected from three ascending-dose tolerability and PK studies (study 1: single 5-day continuous intravenous (IV) infusion with doses ranging from 24-700 mg/m2/cycle; study 2: 10-minute to 3-hour IV infusion once weekly with doses ranging from 16-325 mg/m2/week; study 3: 1-hour IV infusion once daily for 5 days with doses ranging from 3.6-202.8 mg/m2/day). The PK of SAM486A were best estimated by a population linear three-compartment model with NONMEM (version 5) using data from 9 patients in studies 1 through 3. The population pharmacokinetic parameters (SD) were CL = 6.2 (0.4) l/h/m2, Q2 = 15.4 (1.5) l/h/m2, Q3 = 33.6 (5.3) l/h/m2, V1 = 9.5 (1.6) l/m2, V2 = 672 (52) l/m2, and V3 = 39.9 (8.3) l/m2, and the corresponding intersubject variability was 45.4%, 74.0%, 85.3%, 80.1%, 37.0%, and 103%, respectively, where CL is total body clearance, Q2 and Q3 are intercompartmental clearances, and V1, V2, and V3 are the volumes of distribution in central and peripheral compartments, respectively. The intrasubject variability was 24.0%. The cumulative AUC before the onset of neutrophil nadir count (AUC) and the duration of exposure over threshold SAM486A concentrations in the range of 0.05 to 0.1 microM based on Bayesian PK parameter estimates significantly correlated with absolute neutrophil count nadir (< 5 x 10(9)/l). AUC showed the best correlation (R2 = 0.72) with absolute neutrophil count nadir by an inhibitory sigmoid Emax model and also correlated with percent decrease in neutrophil count from baseline to nadir by a simple Emax model (R2 = 0.53). Logistic regression analysis indicated that AUC and the duration of exposure over 0.05 to 0.1 microM, but not Cmax, were strong predictors of grade 4 neutropenia (< 0.5 x 10(9)/l). Drug exposure parameters such as AUC derived from population analysis may be used clinically as a useful predictor of drug-induced neutropenia.

Rituximab (anti-CD20 monoclonal antibody) for the treatment of patients with relapsing or refractory aggressive lymphoma: a multicenter phase II study

Rituximab, a chimeric monoclonal antibody that binds specifically to the CD20 antigen, induced objective responses in 50% of patients with low-grade or follicular B-cell lymphoma. Because most nonfollicular B-cell lymphomas also express the CD20 antigen, we conducted a phase II study to evaluate the efficacy and tolerability of this new agent in patients with more aggressive types of lymphoma. Patients with diffuse large B-cell lymphoma (DLCL), mantle cell lymphoma (MCL), or other intermediate- or high-grade B-cell lymphomas according to the Working Formulation were included in this prospective randomized phase II study if they were in first or second relapse, if they were refractory to initial therapy, if they progressed after a partial response to initial therapy, or if they were elderly (age >60 years) and not previously treated. The patients received 8 weekly infusions of rituximab at the dose of 375 mg/m2 in arm A or one infusion of 375 mg/m2 followed by 7 weekly infusions of 500 mg/m2 in arm B. Patients were evaluated 2 months after the last rituximab infusion. Fifty-four patients were randomized from 9 centers in Europe and Australia (28 in arm A and 26 in arm B). A total of 5 complete responses (CR) and 12 partial responses (PR) were observed among the 54 enrolled patients, with no difference between the two doses. In an intent-to-treat analysis, the CR rate was 9% (CI95%, 3% to 20%) and the PR rate was 22% (CI95%, 12% to 36%), for an overall response rate of 31% (CI95%, 20% to 46%). An analysis of prognostic factors showed that response rates were lower in patients with refractory disease, patients with lymphoma not classified as DLCL, and patients with a tumor larger than 5 cm in diameter. DLCL and MCL patients had response rates of 37% and 33%, respectively. The median time to progression exceeded 246 days for the 17 responding patients. The most frequently reported adverse events were related to an infusion syndrome and were mild: 19% of the patients had a grade 3 related adverse event, slightly more in arm B, and only 1 patient had a grade 4 related adverse event in arm A. Two patients (3.7%) withdrew from treatment because of severe adverse events, one patient in each arm. In this first trial of rituximab in DLCL and MCL, patients experienced a significant clinical activity with a low toxicity. Rituximab has significant activity in DLCL and MCL patients and should be tested in combination with chemotherapy in such patients.