Chronic myeloid leukaemia. STI 571 magnifies the therapeutic dilemma

A review of imatinib mesilate in the treatment of patients with gastrointestinal stromal tumours and chronic myeloid leukaemia

Context. Imatinib mesylate (GlivecÒ, GleevecÒ, Novartis) has made a dramatic impact on the treatment available for both chronic myeloid leukaemia (CML) and gastrointestinal stromal tumours (GISTs). Both are rare diseases that have possibly been unfamiliar to many pharmacists until now.

Objective. To provide readers with a structured overview of CML and GISTs and the trial data available to support the role imatinib is playing in the treatment of these diseases.

Data sources. Published reviews and primary trial results were sourced via Medline to prepare the review. Articles published up to and including August 2002 were considered. Additionally, pertinent books were used to prepare the text and Novartis kindly supplied information currently only available on file at the company. As imatinib has only been available for a short time, all types and sizes of trials were considered for inclusion. The authors made the final decision as to the relevance and therefore subsequent inclusion of data.

Conclusions. Imatinib is a new molecularly targeted therapy for the treatment of CML and GISTs. It has provided an efficacious alternative therapy choice for physicians managing the care of patients suffering from these diseases. In the future there is the possibility that imatinib may demonstrate activity in other disease states characterized by the genetic changes targeted by imatinib. The results of randomized controlled trials in new and existing indications are awaited.

An uneventful pregnancy and delivery, in a case with chronic myeloid leukemia on imatinib

The concomitant occurrence of pregnancy and chronic myelogenous leukemia is uncommon. We describe the successful management of a 24-year-old woman in the first trimester of her pregnancy with chronic myelogenous leukemia (CML) in the chronic phase, who was on treatment with imatinib, which was stopped by 10^th week of pregnancy. Until, she completed full term of pregnancy she was on hydroxyurea. The use of imatinib did not have adverse effects on the fetus. The patient had a normal vaginal delivery and gave birth to a healthy 2500 g girl at 37 weeks of gestation. We conclude that imatinib in the first trimester of pregnant lady with CML, though has particular concern regarding the potential teratogenic and other adverse effects, has shown evidences of safe conception, pregnancy and delivery in ladies with CML.

Chronic myeloid leukemia 2011: successes, challenges, and strategies--proceedings of the 5th annual BCR-ABL1 positive and BCR-ABL1 negative myeloproliferative neoplasms workshop

This report is based on the presentations and discussions at the 5th annual BCR-ABL1 positive and BCR-ABL1 negative myeloproliferative neoplasms (MPN) workshop, which took place immediately following the 52nd American Society of Hematology (ASH) meeting in Orlando, Florida on December 7th-8th, 2011. Relevant data which was presented at the ASH meeting as well as all other recent publications were presented and discussed at the workshop. This report covers front-line therapies of BCR-ABL1-positive leukemias, in addition to addressing some topical biological, pre-clinical and clinical issues, such as new insights into genomic instability and resistance to tyrosine kinase inhibitors (TKIs), risk stratification and optimizing molecular monitoring. A report pertaining to the new therapies and other pertinent preclinical and clinical issues in the BCR-ABL1 negative MPNs is published separately.

Emerging Strategies for the Treatment of Mutant Bcr-Abl T315I Myeloid Leukemia

The lessons learned from the remarkably successful use of the first-generation tyrosine kinase inhibitor (TKI) imatinib in patients with chronic myeloid leukemia resulted in a major paradigm shift in the treatment of many human cancers, and now further lessons are being learned from our enhanced understanding of the molecular mechanisms of resistance to imatinib and second-generation TKIs, particularly dasatinib and nilotinib. Although diverse mechanisms seem to be involved, the principal cause appears to be the emergence of point mutations in the Abl kinase domain that affect drug affinity and some of which impair the efficacy with which the drugs bind. Currently, > 50 different mutations have been identified, and the extent to which they confer resistance varies considerably. One of the more common mutations results from the substitution of isoleucine for threonine at Abl amino acid position 351, known as the T315I mutation. It appears that the precise position of the substitution within the kinase domain dictates the degree of resistance to TKIs, and patients with the T315I mutation develop almost complete resistance to imatinib, dasatinib, and nilotinib. Herein, we discuss the emerging strategies for circumventing resistance associated with the Bcr-Abl T315I mutation.

Cost-utility analysis of imatinib mesylate for the treatment of chronic myelogenous leukemia in the chronic phase

BACKGROUND

Imatinib mesylate is a targeted therapy for the treatment of chronic myeloid leukemia (CML).

OBJECTIVE

The aim of this study was to estimate the incremental cost-utility of imatinib mesylate compared with hydroxyurea in patients with chronic-phase CML for whom first-line treatment with interferon-alpha failed to produce a response.

METHODS

A Markov model was developed to simulate disease progression for hypothetical patients receiving imatinib mesylate or hydroxyurea, who had not previously responded to interferon-a therapy, to determine outcomes in terms of quality-adjusted life-years (QALYs). Costs were estimated from the perspective of the United Kingdom National Health Service. Patient data were derived from previously published trials.

RESULTS

The Markov model simulated the transitions of a hypothetical sample of 1000 chronic-phase CML patients using 1 monthly cycle over the lifetime of the patient sample. Median survival rates were estimated to be 77 months for imatinib mesylate-treated patients and 56 months for hydroxyurea-treated patients. Patients receiving imatinib mesylate accrued 5.95 QALYs, whereas hydroxyurea-treated patients accrued 3.49 QALYs. The estimated per-patient lifetime costs were 110,103 pound sterlings for patients in the imatinib mesylate group and 15,566 pound sterlings for patients in the hydroxyurea group (year-2001 values). The estimated year-2001 incremental cost per QALY gained from using imatinib mesylate compared with hydroxyurea in chronic phase CML was 38,468 pound sterlings.

CONCLUSIONS

In the present model analysis, imatinib mesylate as a second-line treatment for patients with chronic phase CML was found to offer considerable health benefits to patients, but at a cost to the payer. The incremental cost-effectiveness ratio was 38,468 pound sterlings (year-2001 values).

Voltammetric behavior and quantification of the anti-leukemia drug imatinib in bulk form, pharmaceutical formulation, and human serum at a mercury electrode

Imatinib (GleevecTM, ST1571) exemplifies the successful development of a rationally designed molecularly targeted therapy for treatment of a specific cancer. It is a highly promising new drug for the treatment of chronic myelogenous leukemia in blast crisis, in the accelerated or chronic phase after interferon failure or intolerance. The electrochemical behavior of imatinib was studied in Britton–Robinson (B–R) buffers of pH 2 to 11 by means of cyclic voltammetry at a hanging mercury drop electrode. The voltammograms showed a single 2-electron irreversible cathodic peak, which may be attributed to reduction of the C=O double bond of the imatinib molecule. Imatinib exhibited a strong adsorption onto the electrode surface especially in B–R buffers of pH 6 and 7. The adsorptive response of the drug was optimized with respect to the pH of the electrolysis medium, accumulation variables, and instrumental parameters using a square-wave stripping voltammetry technique. A fully validated, simple, sensitive, precise, and selective square-wave adsorptive cathodic stripping voltammetric procedure is described for trace determination of imatinib. The limits of detection (LOD) and quantitation (LOQ) of the bulk imatinib, following preconcentration for 150 s onto the hanging mercury drop electrode, were found to be 2.6 × 10–10 and 8.7 × 10–10 mol/L, respectively. The proposed procedure was successfully applied for quantitation of imatinib in pharmaceutical formulation (Glivec®) and spiked human serum, without the necessity for sample pretreatment or time-consuming extraction or evaporation steps prior to analysis of the drug. LOD and LOQ of 4.6 × 10–10 and 1.5 × 10–9 mol/L, respectively, were achieved after 120 s of preconcentration of the drug spiked in human serum.Key words: imatinib, GleevecTM, Glivec®, ST1571, cyclic voltammetry, square-wave stripping voltammetry, electrochemical behavior, quantification, pharmaceutical formulation, human serum.

Filgrastim-induced stem cell mobilization in chronic myeloid leukaemia patients during imatinib therapy: safety, feasibility and evidence for an efficient in vivo purging

Therapy with imatinib mesylate is limited by cellular resistance in chronic myeloid leukaemia (CML). Further, the limited availability of matching stem cell donors or an unfavourable risk profile for allogeneic stem cell transplantation (SCT) reduces the number of therapeutic options in a number of patients. To assess the possibility of stem cell mobilization (SCM) during imatinib therapy we performed granulocyte colony-stimulating factor (filgrastim)-induced SCM and subsequent aphaeresis in 15 chronic phase and three accelerated phase CML patients. Aphaeresis was successful in 13 patients (72%) (> or =2.0 x 10(6) CD34+ cells/kg body weight) and five (28%) harvests could be obtained, which were negative for BCR/ABL mRNA as assessed by nested-reverse transcription polymerase chain reaction (RT-PCR). All harvests, except one, were negative after first round RT-PCR, implicating a low level of CML cell contamination. There was no significant change in peripheral BCR/ABL transcript load after SCM as assessed by quantitative real-time RT-PCR. Fifteen patients remained stable in complete cytogenetic remission (CCR) during a median observation period of 9.3 months. One patient achieved a molecular remission shortly after SCM. Another patient who exhibited rising BCR/ABL mRNA levels before SCM achieved CCR after autologous SCT with the generated harvest. One patient with a Philadelphia chromosome-negative, BCR/ABL-positive CML showed a cytogenetic relapse 6 months after SCM. We conclude that filgrastim-induced CD34+ cell aphaeresis under simultaneous imatinib medication is safe and feasible in CML patients. Additionally, we found evidence that this procedure could generate stem cell harvests that exhibit non-detectable levels of BCR/ABL mRNA.

Salvage chemotherapy with donor lymphocyte infusion and STI 571 in a patient relapsing with B-lymphoblastic phase chronic myeloid leukemia after allogeneic bone marrow transplantation

Relapse is the main cause of treatment failure following hematopoietic stem cell transplantation for blastic phase chronic myeloid leukemia. Treatment options including donor lymphocyte infusion, second transplantation, interferon- and re-induction chemotherapy are often unsuccessful. We report a patient with blastic phase chronic myeloid leukemia relapsing after allogeneic stem cell transplantation. The post-transplant leukemia was characterized with B-lymphoid markers and multiple genetic abnormalities including double Ph-chromosomes. The disease was treated with three courses of salvage chemotherapy combined with donor lymphocyte infusion and bcr-abl tyrosine kinase inhibitor. The leukemia proved to be non-responsive both to immune therapy and STI 571. The presented case demonstrates the need for combination approaches in post-transplant relapsed leukemia and discusses the possible contributing mechanisms of STI-571 resistance.

Imatinib mesylate, the first molecularly targeted gene suppressor

OBJECTIVE

To review the pharmacology, pharmacokinetics, efficacy, safety, and drug-drug and drug-food interactions of imatinib and the economic considerations of imatinib in the treatment of chronic myeloid leukemia (CML).

DATA SOURCES

Literature accessed through MEDLINE (January 1970-January 2002), abstracts from the 2001 annual meetings of the American Society of Clinical Oncology and the American Society of Hematology, imatinib product labeling, and additional studies or abstracts identified from the bibliographies of the reviewed literature were used to compile data. Key search terms were allogeneic bone marrow transplant and stem cell transplant, chronic myeloid leukemia, imatinib, interferon, Gleevec, leukemia, gastrointestinal stromal tumors, STI-571, and tyrosine kinase inhibitors.

FINDINGS

Imatinib is a distinctively characteristic drug targeted toward inhibition of tyrosine kinase activity. Imatinib is indicated for the treatment of patients with CML who failed interferon (IFN)-alpha therapy and for the treatment of patients with gastrointestinal stromal tumors (GISTs) expressing the tyrosine kinase receptor c-kit. Imatinib produces positive short-term hematologic and cytogenetic responses in patients with CML; short-term positive objective responses have been shown for patients with GISTs. To our knowledge, there are no controlled trials demonstrating long-term safety, improvement in disease-related symptoms, or increased survival with imatinib. Serious adverse effects requiring dosage decreases and/or therapy termination are edema, hepatotoxicity, and hematologic toxicity. Imatinib also has been found to inhibit tyrosine kinases involved in the growth of other malignancies. The role of imatinib in tumors that express a tyrosine kinase is constantly evolving with new research results.

CONCLUSIONS

Imatinib therapy should be limited to patients whose tumor growth is related to a genetically defective tyrosine kinase. In cases of CML, imatinib should be further limited to patients who have tried and failed IFN-alpha therapy or who are not candidates for an allogeneic stem cell transplant.

Tyrosine kinase inhibitor STI571 in the treatment of Philadelphia chromosome-positive leukaemia failing myeloablative stem cell transplantation

Eight patients with Philadelphia chromosome-positive (Ph(+)) leukaemia relapsing from stem cell transplantation (SCT) (one syngeneic and seven allogeneic) were treated with the tyrosine kinase inhibitor STI571. Five patients relapsing as chronic myeloid leukaemia (CML) in chronic phase achieved a complete haematological response, with complete and major cytogenetic responses occurring in four and one cases, respectively. One patient became negative for BCR/ABL in the bone marrow. Three patients relapsed as acute leukaemia (two CML in myeloblastic crisis and one Ph(+) acute lymphoblastic leukaemia), all of whom achieved haematological and cytogenetic responses. One patient also became BCR/ABL negative. However, pancytopenia and graft-versus-host disease led to cessation of treatment in the remaining two cases, which was followed by disease recurrence refractory to further STI treatment. Our results showed that Ph(+) leukaemic relapses after SCT might respond well to STI571 therapy.

Intensive chemotherapy in patients with chronic myelogenous leukaemia (CML) in accelerated or blastic phase--a report from the Swedish CML Group

In attempting to restore the chronic phase (CP) of chronic myelogenous leukaemia (CML), the Swedish CML group utilized an intensive chemotherapy protocol for 83 patients (aged 16-79 years) in accelerated (AP, n = 22) or blastic phase (BC, n = 61). Most patients received a combination of mitoxantrone (12 mg/m2/d) and etoposide (100 mg/m2/d) together with cytosine arabinoside (1 g/m2 b.i.d) for 4 d. Overall, 39 patients (47%) achieved a second CP (CP2)/partial remission (PR). Responding patients < 65 years were eligible for ablative chemotherapy followed by an allogeneic (SCT) or a double autologous stem cell transplant (ASCT). Seventeen of 34 responders < 65 years failed to proceed to transplantation as a result of early disease progression (n = 15) or disease-related complications (n = 2). The remaining 17 patients underwent SCT (n = 9; including four unrelated donor SCT) or ASCT (n = 8). Only one of the eight ASCT patients had a second ASCT; the remaining seven failed because of progression (n = 5) or hypoplasia (n = 2). The median duration of CP2/PR was 6 months (range 1-72 months). Five patients achieved a longer CP2/PR than CP1. The 1 year survival was 70% for SCT/ASCT patients (median survival 21 months), 50% for responding patients overall, but only 7% for non-responders (P < 0.001). Three SCT/ASCT patients are long-term survivors (65+, 66+ and 73+ months). In conclusion, approximately half of the patients achieved a CP2/PR after intensive chemotherapy, with a clear survival advantage for responders vs non-responders. Subsequent SCT/ASCT was feasible for half of the responders (< 65 years), and one individual underwent double ASCT. Novel therapeutic options for CML patients in AP/BP are needed.

Quantification of the anti-leukemia drug STI571 (Gleevec) and its metabolite (CGP 74588) in monkey plasma using a semi-automated solid phase extraction procedure and liquid chromatography-tandem mass spectrometry

Signal Transduction Inhibitor 571 (STI571, formerly known as CGP 57148B) or Gleevec received fast track approval by the US Food and Drug Administration (FDA) for treatment of chronic myeloid leukemia (CML). STI571 (Gleevec) is a revolutionary and promising new oral therapy for CML, which functions at the molecular level with high specificity. The dramatic improvement in efficacy compared with existing treatments prompted an equally profound increase in the pace of development of Gleevec. The duration from first dose in man to completion of the New Drug Application (NDA) filing was less than 3 years. In addition, recently, FDA approved Gleevec for the treatment of gastrointestinal stromal tumor (GIST). In order to support all toxicokinetic (TK) studies with sufficient speed to meet various target dates, a semi-automated procedure using solid phase extraction (SPE) was developed and validated. A Packard Multi-Probe I and a SPE step in a 96-well plate format were utilized. A 3M Empore octyl (C(8))-standard density 96-well plate was used for plasma sample extraction. A Sciex API 3000 triple quadrupole mass spectrometer with an atmospheric pressure chemical ionization (APCI) interface operated in positive ion mode was used for detection. Lower limits of quantification of 1.00 and 2.00 ng/ml were attained for STI571 and its metabolite, CGP 74588, respectively. The method proved to be rugged and allowed the simultaneous quantification of STI571 and CGP 74588 in monkey plasma. Herein, assay development, validation, and representative concentration-time profiles obtained from TK studies are presented.

High-throughput quantification of the anti-leukemia drug STI571 (Gleevec) and its main metabolite (CGP 74588) in human plasma using liquid chromatography-tandem mass spectrometry

The signal transduction inhibitor STI571 (formerly known as CGP 57148B) or Gleevec received fast track approval by the US Food and Drug Administration (FDA) for treatment of chronic myeloid leukemia (CML). STI571 is a revolutionary and promising new oral therapy for CML, which functions at the molecular level with high specificity. The dramatic improvement in efficacy compared to existing treatments prompted an equally profound increase in the pace of development of Gleevec. The duration from first dose in man to completion of the New Drug Application (NDA) filing was approximately 2.6 years. In order to support all pharmacokinetics studies with sufficient speed to meet various target dates, a semi-automated procedure using protein precipitation was developed and validated. A Tomtec Quadra 96 (Model 320) and a protein precipitation step in a 96-well plate format were utilized. A Sciex API 3000 triple quadrupole mass spectrometer with an atmospheric pressure chemical ionization interface operated in positive ion mode was used for detection. The method proved to be rugged and allowed the simultaneous quantification of STI571 and its main metabolite (CGP 74588) in human plasma. Herein, assay development, validation, and representative concentration-time profiles obtained from clinical studies are presented.