Management of ponatinib dosing in chronic myeloid leukemia patients

Ponatinib (Iclusig®, Takeda/Incyte) is a third-generation highly-potent-pan-inhibitor of tyrosine kinases, active in all single resistance ABL kinase mutations including the T315l mutation. It is approved to treat of chronic myeloid leukemia (CML) in every phase of disease-resistant or intolerant to second-generation tyrosine kinase inhibitors (2GTKIs) and for whom imatinib is not clinically appropriate as well as for patients with T315I mutation. The drug is also indicated for Ph+ acute lymphoblastic leukemia (ALL). The approved starting dose for ponatinib is 45 mg once daily. Available data revealed ponatinib dose-dependent increased risk of cardiovascular toxicity. There is still no consensus about the optimal, initial dose of ponatinib and its management during therapy. It is crucial to start treatment with the risk-adjusted dose and assess the benefit-risk profile of ponatinib dosing. Evaluation of dosing modification should be considered during treatment, mainly if toxicity occurs. Our study summarizes current knowledge and recommendations about the choice of starting dose of ponatinib and management of ponatinib dosing during the treatment.

Development and evaluation of a secondary reference panel for BCR-ABL1 quantification on the International Scale

Molecular monitoring of chronic myeloid leukemia patients using robust BCR-ABL1 tests standardized to the International Scale (IS) is key to proper disease management, especially when treatment cessation is considered. Most laboratories currently use a time-consuming sample exchange process with reference laboratories for IS calibration. A World Health Organization (WHO) BCR-ABL1 reference panel was developed (MR¹–MR⁴), but access to the material is limited. In this study, we describe the development of the first cell-based secondary reference panel that is traceable to and faithfully replicates the WHO panel, with an additional MR^4.5 level. The secondary panel was calibrated to IS using digital PCR with ABL1, BCR and GUSB as reference genes and evaluated by 44 laboratories worldwide. Interestingly, we found that >40% of BCR-ABL1 assays showed signs of inadequate optimization such as poor linearity and suboptimal PCR efficiency. Nonetheless, when optimized sample inputs were used, >60% demonstrated satisfactory IS accuracy, precision and/or MR^4.5 sensitivity, and 58% obtained IS conversion factors from the secondary reference concordant with their current values. Correlation analysis indicated no significant alterations in %BCR-ABL1 results caused by different assay configurations. More assays achieved good precision and/or sensitivity than IS accuracy, indicating the need for better IS calibration mechanisms.

A certified plasmid reference material for the standardisation of BCR-ABL1 mRNA quantification by real-time quantitative PCR

Serial quantification of BCR–ABL1 mRNA is an important therapeutic indicator in chronic myeloid leukaemia, but there is a substantial variation in results reported by different laboratories. To improve comparability, an internationally accepted plasmid certified reference material (CRM) was developed according to ISO Guide 34:2009. Fragments of BCR–ABL1 (e14a2 mRNA fusion), BCR and GUSB transcripts were amplified and cloned into pUC18 to yield plasmid pIRMM0099. Six different linearised plasmid solutions were produced with the following copy number concentrations, assigned by digital PCR, and expanded uncertainties: 1.08±0.13 × 10⁶, 1.08±0.11 × 10⁵, 1.03±0.10 × 10⁴, 1.02±0.09 × 10³, 1.04±0.10 × 10² and 10.0±1.5 copies/μl. The certification of the material for the number of specific DNA fragments per plasmid, copy number concentration of the plasmid solutions and the assessment of inter-unit heterogeneity and stability were performed according to ISO Guide 35:2006. Two suitability studies performed by 63 BCR–ABL1 testing laboratories demonstrated that this set of 6 plasmid CRMs can help to standardise a number of measured transcripts of e14a2 BCR–ABL1 and three control genes (ABL1, BCR and GUSB). The set of six plasmid CRMs is distributed worldwide by the Institute for Reference Materials and Measurements (Belgium) and its authorised distributors (https://ec.europa.eu/jrc/en/reference-materials/catalogue/; CRM code ERM-AD623a-f).

Laparoscopic removal of retroperitoneal accessory spleen in patient with relapsing idiopathic thrombocytopenic purpura 30 years after classical splenectomy

The clinical success of therapeutic splenectomy for idiopathic thrombocytopenic purpura depends on the complete removal of all functional splenic tissue. Among reasons for poor response to splenectomy, failure to remove accessory spleens is mentioned. We present our experience with laparoscopic removal of accessory spleen from retroperitoneal space in a patient with relapse of ITP 30 years after classical splenectomy. A 45-year-old female patient underwent in 1972 classical splenectomy for ITP. Progressive decline in thrombocyte count was observed 7 years ago. Scintigraphy, CT, and ultrasound revealed residual splenic tissue. A laparoscopic approach was proposed. Four trocars placed along left costal margin were used. After dissection of all the adhesions behind the pancreatic tail deep in the retroperitoneal space a round structure 4 cm in diameter, macroscopically resembling splenic tissue, was found. The accessory spleen was removed intact. The patient recovered well; 2 months later steroids were discontinued while the thrombocyte level was 251 x 10(9)/L. Identification of accessory spleen seems to be major intraoperative problem. We believe that accessory spleen can be safely removed laparoscopically, avoiding a major open procedure, and a satisfactory postoperative result could be expected.

[Molecular basis of chronic myelogenous leukemia and significance of diagnostic methods based on BCR-ABL gene amplification]

Chronic myelogenous leukemia is characterized by an abnormal 22nd chromosome known as a Philadelphia chromosome, which can be detected in 95% of patients with CML. Molecular equivalent of this aberration is a BCR-ABL translocation resulting in chimeric gene formation. A BCR-ABL chimeric gene plays a key role in the hematopoietic cells proliferation regulation. RT-PCR can be used in diagnosis of CML, to detect chimeric BCR-ABL gene, and to reveal the type of translocation what could have prognostic importance, and in monitoring of minimal residual disease, confirming the eradication of pathological cells clone after treatment and identifying the group of patients with best prognosis and best overall survival. RT-PCR in monitoring of minimal residual disease after allo- or autologous hemopoietic cells transplantation can early reveal relapse of the disease. Detection of molecular relapse is an important prognostic factor and may implicate induction of treatment which should prevent haematological relapse of the disease.

[Harvesting bone marrow from the posterior superior iliac crest for transplantation]

The purpose of bone marrow cells harvesting is to isolate haemopoietic stem cell for the transplantation, by means of multiple punctures from the posterior iliac crest under general anaesthesia. This method is the alternative procedure for collecting circulating peripheral blood progenitor cells performed with continuous-flow cell separators. The aim of the both procedures is the collection of progenitor cells for transplantation in the number enabling reconstitution of marrow function after myeloablative therapy. The bone marrow cell harvesting is a safe measure: the infrequent complication related to general anaesthesia may occur and the simultaneous or subsequent blood transfusion is usually required.

[Autologous hemopoietic stem cell transplantation in treatment of chronic myelogenous leukemia]

Chronic myelogenous leukemia in more than 90% of patients is associated with the abnormal Philadelphia chromosome, which results in aberrant BCR-ABL chimeric gene expression. The mean overall survival on standard chemotherapy (which is not curative) ranges between 54-72 months. Selected patients with CML can be cured by allogeneic hemopoietic stem cell transplantation. Only 30% of patients has an optimal HLA-identical sibling donor. It is possible to find well-matched unrelated donor for another 20-30% of patients, however matched-unrelated donor transplantation is still associated with relative high risk of complications and cannot be used in elderly patients. Interferon alpha treatment in monotherapy or in combination with ARA-C can induce a cytogenetical and molecular remission in selected group of patients, which benefits with significantly prolonged survival. Nevertheless the cost of this treatment is high and long period of therapy is required to assess its efficacy. In patients lacking matched related or unrelated donors for allogeneic transplantation, autologous stem cell transplantation could be the alternative method of treatment. Discussed in the paper method of mobilization and transplantation of Philadelphia-negative peripheral-blood progenitor cells collected during early phase of bone marrow regeneration after "mobilizing" chemotherapy (mini-ICE) enables to achieve a complete or major cytogenetical response in about 77% of patients. There is only minimal morbidity and no transplant-related mortality. This procedure and the post-transplant immunotherapy (IFN alpha, interleukin-2) can considerably suppress the pathological clone and significantly prolong the overall survival in CML patients not eligible for allogeneic transplantation.

[The effect of magnesium on blood coagulation--state of the art literature review from 1959 to 1995]

The effect of magnesium on coagulation system is still an interesting subject for investigations. Shionoya in his publication (1927) reported for the first time possible inhibitory effect of magnesium on coagulation system. Since then, a large number of studies were undertaken to explain the mechanisms of influence of Mg++ on plasma coagulation, platelet function and fibrinolysis. In recent decades, the effect of magnesium on coagulation has led to controversy in a wide range of scientific publications. At present, series of experiments are undertaken in laboratories using modern methodology to evaluate the possible effect of magnesium on coagulation. The results of Anders's and Frisch's study reported here support the theory of the authors, who found no change in coagulation in the presence of physiological concentration of magnesium in blood serum. The influence on the final results, often contradictory, could have: different type of study (in vitro or in vivo), the object of the study (human being, animal), concentrations of magnesium (in most of cases non-physiologic and toxic) and out of date methodology. In majority of reported here studies there were no control groups, and clinical trials were not a double blind studies.

[Fibrinolytic activity and tissue plasminogen activator level in healthy individuals prior to and after a ten-minute venous stasis]

Fibrinolytic activity and tissue plasminogen activator (t-PA) level were measured in 33 healthy individuals prior to and after fibrinolytic system stimulation (i.e. a ten-minute venous stasis). Fibrinolytic activity was measured with the aid of euglobin lysis time, and lysis test on the fibrin plates (in own modification). Tissue plasminogen activator concentration was assayed spectrophotometrically with the COA-SET t-PA (Kabi Vitrum). No fibrinolytic activity of plasma specimens taken before the venous stasis was noted during fibrin lysis plate test whereas it was seen in 13 subjects after the venous stasis. Fibrinolytic activity of the plasma euglobins, measured as a surface on fibrin plates, increased significantly after the venous stasis in both sexes (by 35.5 mm2 on the average, i.e. by 51%). It was more marked in men than in women both prior to and after venous stasis (by 10.9% and 19.0%, respectively). A time of plasma euglobin lysis was shorter after venous stasis (by 110 minutes, on the average). There was no significant difference between the sexes. Tissue plasminogen activator concentration increased by 5.8 times (from 1.7 IU/ml to 9.9 IU/ml) after the stasis. Correlation between t-PA concentrations and fibrinolytic activity, measured on the fibrin plates, was highly positive. No such a correlation existed between t-PA concentrations and the time of euglobin lysis. The obtained results indicate variety of assessments of fibrinolytic system activity.(ABSTRACT TRUNCATED AT 250 WORDS)