STAT3 expression is associated with poor survival in non-elderly adult patients with newly diagnosed multiple myeloma

BACKGROUND: Signal transducer and activator of transcription 3 (STAT3) is not only a key signaling molecule in the regulation of growth but is also involved in malignant transformation. We investigated the prognostic significance of STAT3 expression in 94 non-elderly adult patients (aged 38 to 65 yr) with newly diagnosed multiple myeloma (MM). METHODS: Tumor cell-specific phosphotyrosine-STAT3 (PY-STAT3) expression at the time of diagnosis was evaluated with dual immunohistochemical (IHC) staining for PY-STAT3 and CD138. RESULTS: PY-STAT3 positivity was detected in 10 patients (10.6%), including three who showed strong expression. PY-STAT3-positive patients had higher serum C-reactive protein and calcium levels at diagnosis than did PY-STAT3-negative patients. PY-STAT3 positivity had predictive value for poor progression-free survival (PFS; P=0.001) and overall survival (OS; P=0.003). Among the 60 patients who received frontline autologous stem cell transplantation, PY-STAT3-positive patients had poorer PFS than did PY-STAT3-negative patients (4.2 vs. 19.2 mo, respectively; P=0.013). Multivariate analysis identified PY-STAT3 expression as an independent prognostic factor for PFS (relative risk [RR]=2.706, P=0.014) and OS (RR=3.091, P=0.044). CONCLUSION: These data show that PY-STAT3 positivity, as determined using dual IHC, is a marker of poor prognosis in non-elderly adult patients with MM.

Efficacy of eculizumab in paroxysmal nocturnal hemoglobinuria patients with or without aplastic anemia: prospective study of a Korean PNH cohort

BACKGROUND: Patients with paroxysmal nocturnal hemoglobinuria (PNH) often have concurrent aplastic anemia (AA). This study aimed to determine whether eculizumab-treated patients show clinical benefit regardless of concurrent AA. METHODS: We analyzed 46 PNH patients ≥18 years of age who were diagnosed by flow cytometry and treated with eculizumab for more than 6 months in the prospective Korean PNH registry. Patients were categorized into two groups: PNH patients with concurrent AA (PNH/AA, N=27) and without AA (classic PNH, N=19). Biochemical indicators of intravascular hemolysis, hematological laboratory values, transfusion requirement, and PNH-associated complications were assessed at baseline and every 6 months after initiation of eculizumab treatment. RESULTS: The median patient age was 46 years and median duration of eculizumab treatment was 34 months. Treatment with eculizumab induced rapid inhibition of hemolysis. At 6-month follow-up, LDH decreased to near normal levels in all patients; this effect was maintained until the 36-month follow-up regardless of concurrent AA. Transfusion independence was achieved by 53.3% of patients within the first 6 months of treatment and by 90.9% after 36 months of treatment. The mean number of RBC units transfused was significantly reduced, from 8.5 units during the 6 months prior to initiation of eculizumab to 1.6 units in the first 6 months of treatment, for the total study population; this effect was similar in both PNH/AA and classic PNH. CONCLUSION: This study demonstrated that eculizumab is beneficial in the management of patients with PNH/AA, similar to classic PNH.

Once-Daily OROS Hydromorphone for Management of Cancer Pain: an Open-Label, Multi-Center, Non-Interventional Study

Extended-release osmotic extended-release oral delivery system (OROS) hydromorphone is a strong synthetic opioid designed to maintain a constant blood concentration by once daily dosing. The objective of this observational study was to investigate the clinical usefulness of OROS hydromorphone in patients with cancer pain of moderate to severe intensity. Patients with cancer pain who required strong opioids were administered with OROS hydromorphone for 4 weeks. We assessed changes in pain intensity using a numerical rating scale (NRS) as well as levels of sleep disturbance, breakthrough pain, end-of-dose failure, patient satisfaction, and overall assessment of drug effectiveness based on investigator evaluation. Of the 648 enrolled patients, 553 patients were included in the full analysis set. The mean pain intensity was significantly decreased from the NRS value of 5.07 ± 1.99 to 2.75 ± 1.94 (mean % change of 42.13 ± 46.53, P < 0.001). The degree of sleep disturbance significantly improved (mean NRS change of 1.61 ± 2.57, P < 0.001), and the incidence of breakthrough pain was significantly decreased (mean NRS change of 1.22 ± 2.30, P < 0.001). The experience of end-of-dose failure also significantly decreased from 4.60 ± 1.75 to 3.93 ± 1.70, P = 0.007). The patient satisfaction rate was 72.7%, and 72.9% of investigators evaluated the study drug as effective. OROS hydromorphone was an effective and tolerable agent for cancer pain management. It effectively lowered pain intensity as well as improved sleep disturbance, breakthrough pain, and end-of-dose failure (Identifier: NCT 01273454).

Pralatrexate in Combination with Bortezomib for Relapsed or Refractory Peripheral T Cell Lymphoma in 5 Elderly Patients

Peripheral T cell lymphoma (PTCL) is a heterogeneous group of aggressive lymphomas with poor prognosis. Elderly (age ≥ 65years) patients generally have impaired bone marrow function, altered drug metabolism, comorbidities, and poor functional status. Thus, treatment of elderly patients with relapsed or refractory PTCL remains a challenge for clinicians. A recent study disclosed that pralatrexate has a synergistic effect in combination with bortezomib. Weekly pralatrexate and bortezomib were administered intravenously for 3 weeks in a 4-week cycle. Of 5 patients, one achieved complete response after 4 cycles which has lasted 12 months until now. Another patient attained partial response after 2 cycles. Only 1 patient experienced grade 3 thrombocytopenia and neutropenia. Two patients suffered from grade 3 mucositis. Combination therapy with pralatrexate and bortezomib may be used as a salvage therapy for relapsed or refractory PTCL in the elderly with a favorable safety profile.

Predictive Factors of Mortality in Population of Patients with Paroxysmal Nocturnal Hemoglobinuria (PNH): Results from a Korean PNH Registry

Paroxysmal nocturnal hemoglobinuria (PNH) is a progressive, systemic, life-threatening disease, characterized by chronic uncontrolled complement activation. A retrospective analysis of 301 Korean PNH patients who had not received eculizumab was performed to systematically identify the clinical symptoms and signs predictive of mortality. PNH patients with hemolysis (lactate dehydrogenase [LDH] > or = 1.5 x the upper limit of normal [ULN]) have a 4.8-fold higher mortality rate compared with the age- and sex-matched general population (P < 0.001). In contrast, patients with LDH < 1.5 x ULN have a similar mortality rate as the general population (P = 0.824). Thromboembolism (TE) (odds ratio [OR] 7.11; 95% confidence interval [CI] (3.052-16.562), renal impairment (OR, 2.953; 95% CI, 1.116-7.818) and PNH-cytopenia (OR, 2.547; 95% CI, 1.159-5.597) are independent risk factors for mortality, with mortality rates 14-fold (P < 0.001), 8-fold (P < 0.001), and 6.2-fold (P < 0.001) greater than that of the age- and sex-matched general population, respectively. The combination of hemolysis and 1 or more of the clinical symptoms such as abdominal pain, chest pain, or dyspnea, resulted in a much greater increased mortality rate when compared with patients with just the individual symptom alone or just hemolysis. Early identification of risk factors related to mortality is crucial for the management of PNH. This trial was registered at www.clinicaltrials.gov as NCT01224483.

Predictive Efficacy of Interim Positron Emission Tomography/Computed Tomography (PET/CT) for the Treatment of Aggressive Lymphoma / 전남의대학술지

The prognostic value of whole-body positron emission tomography/computed tomography (PET/CT) with 18F-fluoro-2-deoxy-D-glucose (FDG) shortly after the onset of induction chemotherapy or mid treatment could help to predict long-term clinical outcomes in patients with Hodgkin's or Non-Hodgkin's lymphoma. However, FDG is not a tumor-specific substance, and it may accumulate to the point of being detected in a variety of benign conditions or at physiologic anatomical sites, which may give rise to false-positive interpretation. In an attempt to standardize the reporting criteria for interim PET/CT, the First International Workshop on Interim PET in Lymphoma suggested visual response criteria with the Deauville five-point scale, and the standardized uptake value (SUV) has been investigated in comparison with this visual system. A quantitative approach using the measurement of maximal SUV (SUVmax) or the reduction rate of SUVmax (DeltaSUVmax) might be more appropriate in early-response PET/CT for reducing false-positive rates or for decreasing interobserver variability in interpretation. In this review, the predictive efficacy of PET/CT is discussed for the treatment of aggressive lymphoma, especially in terms of an interim PET/CT-based prognostic model.

Dendritic Cell-Based Cancer Immunotherapy against Multiple Myeloma: From Bench to Clinic / 전남의대학술지

Although the introduction of stem cell transplantation and novel agents has improved survival, multiple myeloma (MM) is still difficult to cure. Alternative approaches are clearly needed to prolong the survival of patients with MM. Dendritic cell (DC) therapy is a very promising tool immunologically in MM. We developed a method to generate potent DCs with increased Th1 polarization and migration ability for inducing strong myeloma-specific cytotoxic T lymphocytes. In this review, we discuss how the efficacy of cancer immunotherapy using DCs can be improved in MM.

Efficacy and safety of eltrombopag in adult refractory immune thrombocytopenia

BACKGROUND: Eltrombopag is a thrombopoietin receptor agonist with excellent treatment outcomes in immune thrombocytopenia (ITP). Here, we analyzed the dose of eltrombopag required to achieve and maintain safe platelet counts in Korean ITP patients. METHODS: Adult refractory ITP patients ( or =50,000 cells/microL). After achieving the target platelet count, the dose of concomitant ITP medications and eltrombopag was reduced to identify the lowest effective dose required to maintain the platelet count. RESULTS: Among 18 patients, 66.7% achieved complete response, 5.6% achieved platelet counts between 50,000 and 100,000 cells/microL, and 27.8% failed to achieve the target platelet count. The median ITP duration was significantly shorter in patients who achieved the target platelet count. The initial dose required to achieve the target platelet count was 25 mg/d. The adjusted maintenance doses were 25 mg twice per week or 25 mg/d. After discontinuation, 83.3% relapsed, and the median relapse-free survival was 15 days. Two relapsed and 1 failed patient switched to romiplostim. The response to romiplostim was similar to eltrombopag. During eltrombopag treatment, 38.9% showed hepatobiliary laboratory anomalies. Among 9 follow-up bone marrow examinations, 1 revealed fibrosis after 1 year of treatment. CONCLUSION: Eltrombopag was well tolerated with excellent treatment outcomes in refractory adult ITP patients. Low-dose eltrombopag effectively maintained the target platelet count. However, some patients required longer or higher-dose treatment to maintain the target platelet count, especially in heavily pretreated or longer ITP cases.

Korean Guidelines for Treating Chronic Myelogenous Leukemia - The Korean Society of Hematology Chronic Myelogenous Leukemia Working Party / 대한내과학회지

BACKGROUND/AIMS: The first edition of the Korean treatment guidelines for chronic myelogenous leukemia (CML) was published in 2006. We intend to update those guidelines to include the use of next-generation tyrosine kinase inhibitors (TKIs). METHODS: New guidelines were developed in 2012 based on the results of a survey and a consensus meeting of various Korean experts, the reports of recent clinical studies, and updated guidelines from external study groups. RESULTS: An assessment of risk factors is strongly recommended before treating newly diagnosed chronic phase CML. Imatinib, dasatinib, and nilotinib are reimbursable in Korea as first-line treatments, and the patient's age, comorbidities, and possible adverse events should be considered in the choice of treatment. Molecular studies are recommended for assessing treatment efficacy instead of invasive cytogenetic response evaluations, and an early response is believed to correlate with a good prognosis. Second-line TKIs can be considered for patients who fail or are intolerant of first-line therapy, pending analysis of ABL tyrosine kinase mutation status. For treating advanced stages, a combination of TKIs with cytotoxic agents and hematopoietic cell transplantation is recommended. The adverse effects of TKI therapy can be managed via dose reduction and supportive care, or switching to an alternate TKI. CONCLUSIONS: The use of TKIs has improved the outcome of CML treatment. Treatment-free remission after discontinuing TKIs might be possible in select patients who achieve sufficient response, indicating that curative treatment for CML can be expected in the future.

Incidences and Prognostic Impact of c-KIT, WT1, CEBPA, and CBL Mutations, and Mutations Associated With Epigenetic Modification in Core Binding Factor Acute Myeloid Leukemia: A Multicenter Study in a Korean Population

BACKGROUND: To identify potential molecular prognostic markers in core binding factor (CBF) AML, we analyzed incidences and prognostic impacts of mutations in c-KIT, WT1, CEBPA, CBL, and a number of epigenetic genes in CBF AML. METHODS: Seventy one and 21 AML patients with t(8;21) and inv(16) were enrolled in this study, respectively. NPM1, CEBPA, c-KIT, IDH1/2, DNMT3A, EZH2, WT1, and CBL mutations were analyzed by direct sequencing. Patients were categorized with respect to c-KIT and WT1 mutation status, and both clinical features and prognoses were compared. RESULTS: The incidences of FLT3 internal tandem duplication (ITD), NPM1, CEBPA, IDH1/2, DNMT3A, EZH2, and CBL mutations were low (< or =5%) in CBF AML patients. However, c-KIT and WT1 mutations occurred frequently (10.9% and 13.8%, respectively). t(8;21) patients with c-KIT mutations showed significantly shorter overall survival (OS) and disease free survival (DFS) periods than those without mutations (P<0.001, for both); however, although the limited number of t(8;21) patients were analyzed, WT1 mutation status did not affect prognosis significantly. Relapse or death during follow-up occurred more frequently in t(8;21) patients carrying c-KIT mutations than in those without the mutation, although the difference was significant only in a specific patient subgroup with no WT1 mutations (P=0.014). CONCLUSIONS: The incidences of mutations in epigenetic genes are very low in CBF AML; however, c-KIT and WT1 mutations occur more frequently than others. The poor prognostic impact of c-KIT mutation in t(8;21) AML patients only applies in a specific patient subgroup without WT1 mutations. The prognostic impact of WT1 mutation in CBF AML is not evident and further investigation is required.

Prediction of survival by applying current prognostic models in diffuse large B-cell lymphoma treated with R-CHOP followed by autologous transplantation

BACKGROUND: Among the currently available prognostic models for diffuse large B-cell lymphoma (DLBCL), we investigated to determine which is most adoptable for DLBCL patients treated with rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) followed by upfront autologous stem cell transplantation (auto-SCT). METHODS: We retrospectively evaluated survival differences among risk groups based on the International Prognostic Index (IPI), the age-adjusted IPI (aaIPI), the revised IPI (R-IPI), and the National Comprehensive Cancer Network IPI (NCCN-IPI) at diagnosis in 63 CD20-positive DLBCL patients treated with R-CHOP followed by upfront auto-SCT. RESULTS: At the time of auto-SCT, 74.6% and 25.4% of patients had achieved complete remission and partial remission after R-CHOP, respectively. As a whole, the 5-year overall (OS) and progression-free survival (PFS) rates were 78.8% and 74.2%, respectively. The 5-year OS and PFS rates according to the IPI, aaIPI, R-IPI, and NCCN-IPI did not significantly differ among the risk groups for each prognostic model (P-values for OS: 0.255, 0.337, 0.881, and 0.803, respectively; P-values for PFS: 0.177, 0.904, 0.295, and 0.609, respectively). CONCLUSION: There was no ideal prognostic model among those currently available for CD20-positive DLBCL patients treated with R-CHOP followed by upfront auto-SCT.

Oliguria as an early indicator of mortality risk in patients with multiple myeloma and renal impairment

BACKGROUND: A change in urine output has been recently recognized as a valuable biomarker of acute kidney injury that is associated with mortality in critically ill patients. We investigated the prognostic impact of oliguria for survival outcomes in multiple myeloma (MM) patients presenting with renal impairment (RI). METHODS: Retrospective data on 98 patients with MM and RI, who received initial treatment with novel therapies, were analyzed. Oliguria was defined as a urine output of <0.5 mL/kg/h. RESULTS: The baseline median eGFR was 39.7 mL/min (range, 5.1-59.8). Achievement of renal complete response (CR) was observed in 39.8% of patients. Nine patients (9.2%) presented with oliguria at initial diagnosis, and 4 initially required dialysis. Over a median follow-up period of 17.1 months (range, 1.7-100.0), the median overall survival (OS) was 38.7 months (95% CI 25.0-52.5). Multivariate analyses indicated that oliguria at diagnosis [hazard ratio (HR) 3.628, 95% CI 1.366-9.849, P=0.011], and thrombocytopenia <100x10(9)/L at diagnosis (HR 2.534, 95% CI 1.068-6.015, P=0.035), were significantly associated with overall survival. CONCLUSION: Oliguria was significantly associated with higher mortality in MM patients with RI. Therefore, close monitoring of urine output could be important for these patients.

Predictive Efficacy of Interim Positron Emission Tomography/Computed Tomography (PET/CT) for the Treatment of Aggressive Lymphoma / 전남의대학술지

The prognostic value of whole-body positron emission tomography/computed tomography (PET/CT) with 18F-fluoro-2-deoxy-D-glucose (FDG) shortly after the onset of induction chemotherapy or mid treatment could help to predict long-term clinical outcomes in patients with Hodgkin's or Non-Hodgkin's lymphoma. However, FDG is not a tumor-specific substance, and it may accumulate to the point of being detected in a variety of benign conditions or at physiologic anatomical sites, which may give rise to false-positive interpretation. In an attempt to standardize the reporting criteria for interim PET/CT, the First International Workshop on Interim PET in Lymphoma suggested visual response criteria with the Deauville five-point scale, and the standardized uptake value (SUV) has been investigated in comparison with this visual system. A quantitative approach using the measurement of maximal SUV (SUVmax) or the reduction rate of SUVmax (DeltaSUVmax) might be more appropriate in early-response PET/CT for reducing false-positive rates or for decreasing interobserver variability in interpretation. In this review, the predictive efficacy of PET/CT is discussed for the treatment of aggressive lymphoma, especially in terms of an interim PET/CT-based prognostic model.

Guidelines for the management of myeloproliferative neoplasms

Polycythemia vera, essential thrombocythemia, and primary myelofibrosis are collectively known as 'Philadelphia-negative classical myeloproliferative neoplasms (MPNs).' The discovery of new genetic aberrations such as Janus kinase 2 (JAK2) have enhanced our understanding of the pathophysiology of MPNs. Currently, the JAK2 mutation is not only a standard criterion for diagnosis but is also a new target for drug development. The JAK1/2 inhibitor, ruxolitinib, was the first JAK inhibitor approved for patients with intermediate- to high-risk myelofibrosis and its effects in improving symptoms and survival benefits were demonstrated by randomized controlled trials. In 2011, the Korean Society of Hematology MPN Working Party devised diagnostic and therapeutic guidelines for Korean MPN patients. Subsequently, other genetic mutations have been discovered and many kinds of new drugs are now under clinical investigation. In view of recent developments, we have revised the guidelines for the diagnosis and management of MPN based on published evidence and the experiences of the expert panel. Here we describe the epidemiology, new genetic mutations, and novel therapeutic options as well as diagnostic criteria and standard treatment strategies for MPN patients in Korea.

Treatment of BK virus-associated hemorrhagic cystitis with low-dose intravenous cidofovir in patients undergoing allogeneic hematopoietic cell transplantation

BACKGROUND/AIMS: BK virus (BKV) has been associated with late-onset hemorrhagic cystitis (HC) in recipients of hematopoietic stem cell transplantation (HSCT). Cidofovir has been used at higher doses (3 to 5 mg/kg/wk) with probenecid prophylaxis; however, cidofovir may result in nephrotoxicity or cytopenia at high doses. METHODS: Allogeneic HSCT recipients with BKV-associated HC are treated with 1 mg/kg intravenous cidofovir weekly at our institution. A microbiological response was defined as at least a one log reduction in urinary BKV viral load, and a clinical response was defined as improvement in symptoms and stability or reduction in cystitis grade. RESULTS: Eight patients received a median of 4 weekly (range, 2 to 11) doses of cidofovir. HC occurred a median 69 days (range, 16 to 311) after allogeneic HSCT. A clinical response was detected in 7/8 patients (86%), and 4/5 (80%) had a measurable microbiological response. One patient died of uncontrolled graft-versus-host disease; therefore, we could not measure the clinical response to HC treatment. One microbiological non-responder had a stable BKV viral load with clinical improvement. Only three patients showed transient grade 2 serum creatinine toxicities, which resolved after completion of concomitant calcineurin inhibitor treatment. CONCLUSIONS: Weekly intravenous low-dose cidofovir without probenecid appears to be a safe and effective treatment option for patients with BKV-associated HC.

Dendritic Cell-Based Cancer Immunotherapy against Multiple Myeloma: From Bench to Clinic / 전남의대학술지

Although the introduction of stem cell transplantation and novel agents has improved survival, multiple myeloma (MM) is still difficult to cure. Alternative approaches are clearly needed to prolong the survival of patients with MM. Dendritic cell (DC) therapy is a very promising tool immunologically in MM. We developed a method to generate potent DCs with increased Th1 polarization and migration ability for inducing strong myeloma-specific cytotoxic T lymphocytes. In this review, we discuss how the efficacy of cancer immunotherapy using DCs can be improved in MM.

Dendritic Cell-Based Cancer Immunotherapy against Multiple Myeloma: From Bench to Clinic / 전남의대학술지

Although the introduction of stem cell transplantation and novel agents has improved survival, multiple myeloma (MM) is still difficult to cure. Alternative approaches are clearly needed to prolong the survival of patients with MM. Dendritic cell (DC) therapy is a very promising tool immunologically in MM. We developed a method to generate potent DCs with increased Th1 polarization and migration ability for inducing strong myeloma-specific cytotoxic T lymphocytes. In this review, we discuss how the efficacy of cancer immunotherapy using DCs can be improved in MM.

OCT-1, ABCB1, and ABCG2 Expression in Imatinib-Resistant Chronic Myeloid Leukemia Treated with Dasatinib or Nilotinib / 전남의대학술지

This study explored drug transporter expression levels and their impact on clinical response to imatinib and second-generation tyrosine kinase inhibitors (TKIs) in imatinib- resistant chronic myeloid leukemia (CML). Imatinib-resistant chronic phase CML patients treated with dasatinib (n=10) and nilotinib (n=12) were enrolled. The mRNA expression of the OCT-1, ABCG2, and ABCB1 genes was quantified by using paired bone marrow samples obtained before administering imatinib and at the point of detecting imatinib resistance (just before starting second-generation TKIs). The expression levels of OCT-1 and ABCG2 were lower in follow-up than in imatinib-naive samples. ABCB1 revealed highly variable expression levels before and after imatinib treatment. In addition, median ABCB1 expression in follow-up samples was lower in patients achieving complete cytogenetic response or major molecular response during imatinib treatment than in failed patients. Higher ABCG2 expression in imatinib-exposed samples showed a negative impact on optimal response to dasatinib. Patients with higher ABCG2 expression in imatinib-exposed samples also had shorter progression- free survival with dasatinib treatment. However, no significant correlation was found between these drug transporter expression levels in imatinib-naive or imatinib- exposed samples and responses to nilotinib. In imatinib-resistant CML, OCT-1 and ABCG2 mRNA expression decreased after imatinib treatment. Patients with higher ABCG2 expression in imatinib-exposed samples showed poor treatment outcome with dasatinib. On the other hand, a higher expression level of ABCB1 in imatinib-exposed samples did not affect second-generation TKI responses but was correlated with poor imatinib responses.

Prevention of Venous Thromboembolism, 2nd Edition: Korean Society of Thrombosis and Hemostasis Evidence-Based Clinical Practice Guidelines

In 2010, we proposed the first Korean Guidelines for the Prevention of Venous Thromboembolism (VTE). It was applicable to Korean patients, by modifying the contents of the second edition of the Japanese guidelines for the prevention of VTE and the 8th edition of the American College of Chest Physicians (ACCP) evidence-based clinical practice guidelines. From 2007 to 2011, we conducted a nationwide study regarding the incidence of VTE after major surgery using the Health Insurance Review and Assessment Service (HIRA) database. In addition, we have considered the 9th edition of the ACCP Evidenced-Based Clinical Practice Guidelines, published in 2012. It emphasized the importance of clinically relevant events as opposed to asymptomatic outcomes with preferences for both thrombotic and bleeding outcomes. Thus, in the development of the new Korean guidelines, three major points were addressed: 1) the new guidelines stratify patients into 4 risk groups (very low, low, moderate, and high) according to the actual incidence of symptomatic VTE from the HIRA databases; 2) the recommended optimal VTE prophylaxis for each group was modified according to condition-specific thrombotic and bleeding risks; 3) guidelines are intended for general information only, are not medical advice, and do not replace professional medical care and/or physician advice.

OCT-1, ABCB1, and ABCG2 Expression in Imatinib-Resistant Chronic Myeloid Leukemia Treated with Dasatinib or Nilotinib / 전남의대학술지

This study explored drug transporter expression levels and their impact on clinical response to imatinib and second-generation tyrosine kinase inhibitors (TKIs) in imatinib- resistant chronic myeloid leukemia (CML). Imatinib-resistant chronic phase CML patients treated with dasatinib (n=10) and nilotinib (n=12) were enrolled. The mRNA expression of the OCT-1, ABCG2, and ABCB1 genes was quantified by using paired bone marrow samples obtained before administering imatinib and at the point of detecting imatinib resistance (just before starting second-generation TKIs). The expression levels of OCT-1 and ABCG2 were lower in follow-up than in imatinib-naive samples. ABCB1 revealed highly variable expression levels before and after imatinib treatment. In addition, median ABCB1 expression in follow-up samples was lower in patients achieving complete cytogenetic response or major molecular response during imatinib treatment than in failed patients. Higher ABCG2 expression in imatinib-exposed samples showed a negative impact on optimal response to dasatinib. Patients with higher ABCG2 expression in imatinib-exposed samples also had shorter progression- free survival with dasatinib treatment. However, no significant correlation was found between these drug transporter expression levels in imatinib-naive or imatinib- exposed samples and responses to nilotinib. In imatinib-resistant CML, OCT-1 and ABCG2 mRNA expression decreased after imatinib treatment. Patients with higher ABCG2 expression in imatinib-exposed samples showed poor treatment outcome with dasatinib. On the other hand, a higher expression level of ABCB1 in imatinib-exposed samples did not affect second-generation TKI responses but was correlated with poor imatinib responses.