Tasigna for chronic and accelerated phase Philadelphia chromosome--positive chronic myelogenous leukemia resistant to or intolerant of imatinib

A Comprehensive Review of Cancer Drug-Induced Cardiotoxicity in Blood Cancer Patients: Current Perspectives and Therapeutic Strategies

OPINION STATEMENT

Cardiotoxicity has emerged as a serious outcome catalyzed by various therapeutic targets in the field of cancer treatment, which includes chemotherapy, radiation, and targeted therapies. The growing significance of cancer drug-induced cardiotoxicity (CDIC) and radiation-induced cardiotoxicity (CRIC) necessitates immediate attention. This article intricately unveils how cancer treatments cause cardiotoxicity, which is exacerbated by patient-specific risks. In particular, drugs like anthracyclines, alkylating agents, and tyrosine kinase inhibitors pose a risk, along with factors such as hypertension and diabetes. Mechanistic insights into oxidative stress and topoisomerase-II-B inhibition are crucial, while cardiac biomarkers show early damage. Timely intervention and prompt treatment, especially with specific agents like dexrazoxane and beta-blockers, are pivotal in the proactive management of CDIC.

Nilotinib exhibits less toxicity than imatinib and influences the immune state by modulating iNOS, p-p38 and p-JNK in LPS/IFN gamma-activated macrophages

In this study, we aimed to analyze the effects of first and second-generation Bcr-Abl tyrosine kinase inhibitors, imatinib and nilotinib on LPS/IFN gamma activated RAW 264.7 macrophages. Our data revealed that imatinib was less effective on nitrite levels and more toxic on macrophages compared to nilotinib. Therefore, we further analysed the effect of nilotinib on various inflammatory markers including iNOS, COX-2, NFkB, IL-6, p-ERK, p-p38 and p-JNK in LPS/IFN gamma activated RAW264.7 macrophages. Spectrophotometric viability test and Griess assay,western blot, RT-PCR and luciferase reporter assays were used to analyze the biological activity of nilotinib. Our findings revealed that nilotinib decreases nitrite levels, iNOS mRNA, iNOS and p-p38 protein expressions significantly whereas induces IL-6 mRNA and p-JNK protein expressions at particular doses. We did not find significant effect of nilotinib on COX-2, p-ERK and nuclear p65 proteins and NFkB transcriptional activity. In addition, the binding mode of nilotinib to iNOS protein was predicted by molecular docking. According to the docking analyses, nilotinib exhibited hydrophobic interactions between MET349, ALA191, VAL346, PHE363, TYR367, MET368, CYS194, TRP366 residues at the binding pocket and the molecule as well as van der Waals interactions at specific residues. In conclusion, our results reveal that, in addition to its anticancer activity, nilotinib can exhibit immune modulatory effects on macrophages through its effects on iNOS, IL-6, p-p38 and p-JNK.

Which Second-Line Tyrosine Kinase Inhibitor(s) for Chronic Myeloid Leukemia?

OPINION STATEMENT

In patients with chronic myeloid leukemia who require second-line tyrosine kinase inhibitor therapy, many options exist. These treatments include alternate generation tyrosine kinase inhibitors and in some cases consideration of allogeneic transplant. Although efficacious, each tyrosine kinase inhibitor possesses distinct side effects and pharmacological profiles that prevent a generalizable treatment approach. Furthermore, there is limited head-to-head trial data that would suggest the superiority of one tyrosine kinase inhibitor over another to help guide treatment decisions in specific clinical settings. Therefore, we treat each patient independently. A patient's treatment plan must be personalized by a variety of clinical factors to optimize response and tolerability. Our general approach is to first examine the reason for treatment failure, which may be due to either intolerance or relapse. Second, we consider the age and patient's comorbidities such as lung disease, diabetes, or cardiovascular disease. In patients who have inadequate responses, we analyze the patient's BCR-ABL1 mutational profile, which is beneficial if that patient harbors a specific tyrosine kinase inhibitor responsive mutation, such as T315I. Using these steps, we can provide a generalizable approach to choosing the appropriate second-line tyrosine inhibitor for chronic myeloid leukemia.

Pharmacokinetics, Bioequivalence, and Safety Studies of a Generic Selective Tyrosine Kinase Inhibitor Nilotinib Capsule Versus a Branded Product in Healthy Chinese Volunteers

Nilotinib, a second-generation tyrosine kinase inhibitor (TKI), has been approved in the United States and Europe as a treatment for patients with newly diagnosed chronic myeloid leukemia (CML)-chronic phase (CP) and patients with CML-CP or chronic myeloid leukemia-accelerated phase (CML-AP) who are resistant or intolerant to imatinib (a first-generation TKI). This study compared the bioequivalence and safety of the test nilotinib capsule and reference nilotinib capsule (Tasigna, Novartis) in healthy Chinese volunteers under fasting conditions for marketing authorization in China. The results of the study are reported for the first time. This was a single-dose, randomized, open-label, two-period, and cross-over study. Thirty healthy volunteers were randomly assigned to receive a single dose of a 200-mg test or reference capsule under fasting conditions in each period with a 10-day washout. Plasma samples were analyzed with liquid chromatography-tandem mass spectrometry. Pharmacokinetic parameters were calculated with WinNonlin software. The geometric mean ratio and the corresponding 90% confidence intervals of C_max , AUC_0-t , and AUC_0-∞ for nilotinib between the two fixed-dose combination formulations were within the bioequivalence acceptance range of 80%-125%, therefore the generic and branded formulations were bioequivalent in healthy Chinese volunteers.

Potential Approaches Versus Approved or Developing Chronic Myeloid Leukemia Therapy

Tyrosine kinase inhibitors (TKIs) have revolutionized the treatment of patients with chronic myeloid leukemia (CML). However, continued use of these inhibitors has contributed to the increase in clinical resistance and the persistence of resistant leukemic stem cells (LSCs). So, there is an urgent need to introduce additional targeted and selective therapies to eradicate quiescent LSCs, and to avoid the relapse and disease progression. Here, we focused on emerging BCR-ABL targeted and non-BCR-ABL targeted drugs employed in clinical trials and on alternative CML treatments, including antioxidants, oncolytic virus, engineered exosomes, and natural products obtained from marine organisms that could pave the way for new therapeutic approaches for CML patients.

QT Prolongation in Cancer Patients

Background: QT prolongation and torsades de pointes pose a major concern for cardiologists and oncologists. Although cancer patients are suspected to have prolonged QT intervals, this has not been investigated in a large population. The purpose of this study was to analyze the QT interval distribution in a cancer population and compare it to a non-cancer population in the same institution. Methods: The study was a retrospective review of 82,410 ECGs performed in cancer patients (51.8% women and 48.2% men) and 775 ECGs performed in normal stem cell donors (47.9% women and 52.1% men) from January 2009 to December 2013 at the University of Texas MD Anderson Cancer Center. Pharmacy prescription data was also collected and analyzed during the same time period. Correction of the QT interval for the heart rate was performed using the Bazett and Fridericia formulas. Results: After QT correction for heart rate by the Fridericia formula (QTcF), the mean and 99% percentile QTc for cancer patients were 414 and 473 ms, respectively. These were significantly longer than the normal stem cell donors, 407 and 458 ms, p < 0.001, respectively. Among the cancer patients, the QTc was longer in the inpatient setting when compared to both outpatient and emergency center areas. The most commonly prescribed QT prolonging medications identified were ondansetron and methadone. Conclusion: Our study demonstrates significantly longer QTc intervals in cancer patients, especially in the inpatient setting. Frequently prescribed QT prolonging medications such as antiemetics and analgesics may have a causative role in QT prolongation seen in our cancer hospital.

Response and Resistance to BCR-ABL1-Targeted Therapies

Chronic myeloid leukemia (CML), caused by constitutively active BCR-ABL1 fusion tyrosine kinase, has served as a paradigm for successful application of molecularly targeted cancer therapy. The development of the tyrosine kinase inhibitor (TKI) imatinib allows patients with CML to experience near-normal life expectancy. Specific point mutations that decrease drug binding affinity can produce TKI resistance, and second- and third-generation TKIs largely mitigate this problem. Some patients develop TKI resistance without known resistance mutations, with significant heterogeneity in the underlying mechanism, but this is relatively uncommon, with the majority of patients with chronic phase CML achieving long-term disease control. In contrast, responses to TKI treatment are short lived in advanced phases of the disease or in BCR-ABL1-positive acute lymphoblastic leukemia, with relapse driven by both BCR-ABL1 kinase-dependent and -independent mechanisms. Additionally, the frontline CML treatment with second-generation TKIs produces deeper molecular responses, driving disease burden below the detection limit for a greater number of patients. For patients with deep molecular responses, up to half have been able to discontinue therapy. Current efforts are focused on identifying therapeutic strategies to drive deeper molecular responses, enabling more patients to attempt TKI discontinuation.

Preparation and Characterization of a Novel Swellable and Floating Gastroretentive Drug Delivery System (sfGRDDS) for Enhanced Oral Bioavailability of Nilotinib

Regarding compliance and minimization of side effects of nilotinib therapy, there is a medical need to have a gastroretentive drug delivery system (GRDDS) to enhance the oral bioavailability that is able to administer an optimal dose in a quaque die (QD) or daily manner. In this study, the influence on a swelling and floating (sf) GRDDS composed of a polymeric excipient (HPMC 90SH 100K, HEC 250HHX, or PEO 7000K) and Kollidon^® SR was examined. Results demonstrated that PEO 7000K/Kollidon SR (P/K) at a 7/3 ratio was determined to be a basic GRDDS formulation with optimal swelling and floating abilities. MCC PH102 or HPC_sssl,SFP was further added at a 50% content to this basic formulation to increase the tablet hardness and release all of the drug within 24 h. Also, the caplet form and capsule form containing the same formulation demonstrated higher hardness for the former and enhanced floating ability for the latter. A pharmacokinetic study on rabbits with pH values in stomach and intestine similar to human confirmed that the enhanced oral bioavailability ranged from 2.65–8.39-fold with respect to Tasigna, a commercially available form of nilotinib. In conclusion, the multiple of enhancement of the oral bioavailability of nilotinib with sfGRDDS could offer a pharmacokinetic profile with therapeutic effectiveness for the QD administration of a reasonable dose of nilotinib, thereby increasing compliance and minimizing side effects.

U.S. Food and Drug Administration Benefit-Risk Assessment of Nilotinib Treatment Discontinuation in Patients with Chronic Phase Chronic Myeloid Leukemia in a Sustained Molecular Remission

On December 22, 2017, the U.S. Food and Drug Administration (FDA) updated the product label for nilotinib to include information for providers on how to discontinue this drug in certain patients. With the updated dosing recommendations, select patients with chronic phase myeloid leukemia (CML) taking nilotinib for 3 years or more and whose leukemia has responded with sustained molecular remission (MR4.5, BCR-ABL transcripts of ≤0.0032%) as determined by a FDA-approved test may be eligible to discontinue nilotinib. The updated dosing regimen was based on the efficacy results from two trials that measured how long patients could stop taking nilotinib without the leukemia returning (treatment-free remission). Trial results demonstrated that, among selected patients who received nilotinib as first-line therapy or after transition from imatinib, approximately 50% continued to be in remission at 96 weeks after stopping therapy. Relapses continued to occur throughout the study, indicating that long-term monitoring is needed for safety and disease monitoring. Discontinuation of treatment was associated with an increased risk of low grade musculoskeletal adverse events, some of which were prolonged. Overall, the results support the approval of updates to the dosing recommendations with regard to treatment discontinuation in selected patients who have received nilotinib for at least 3 years, are in a sustained molecular remission, and who can undergo appropriate monitoring. IMPLICATIONS FOR PRACTICE: The updated dosing information provides eligibility criteria for treatment discontinuation, strict monitoring criteria after nilotinib discontinuation, and guidance for treatment reinitiation in eligible patients with chronic phase myeloid leukemia. About half of appropriately selected patients remained in remission 96 weeks after treatment discontinuation. Patients may experience musculoskeletal pain on withdrawal of treatment, incidence of which appears to decrease over time; however, some patients may have long lasting events. The decision to withdraw or continue treatment with nilotinib should be based on clinical condition and patient preferences.

Clinical Pharmacokinetic and Pharmacodynamic Overview of Nilotinib, a Selective Tyrosine Kinase Inhibitor

Nilotinib, an oral inhibitor of the tyrosine kinase activity of Abelson protein, is approved for the treatment of patients with newly diagnosed chronic myeloid leukemia (CML) in chronic phase and patients with CML in chronic phase or accelerated phase resistant or intolerant to prior therapies. This review describes the pharmacokinetic and pharmacodynamic data of nilotinib in patients with CML and in healthy volunteers. Nilotinib is rapidly absorbed, with a peak serum concentration approximately 3 hours after dosing. The area under the plasma drug concentration-time curve over 24 hours and the peak serum concentration of nilotinib were dose proportional from 50-400 mg once daily. The metabolism of nilotinib is primarily via hepatic cytochrome P450 (CYP) 3A4 according to in vitro studies. In the clinical setting, exposure to nilotinib was significantly reduced by the induction of CYP3A4 with rifampicin and significantly increased by the inhibition of CYP3A with ketoconazole. Additionally, nilotinib is a competitive inhibitor of CYP3A4/5, CYP2C8, CYP2C9, CYP2D6, and uridine diphosphate glucuronosyltransferase 1A1. The bioavailability of nilotinib is increased by up to 82% when given with a high-fat meal compared with fasted state. There is a positive correlation between the occurrences of all-grade total bilirubin elevations and the steady-state nilotinib trough concentrations. Fredericia method corrected QT interval change from baseline was observed to have a correlation with nilotinib exposure. No significant relationship between nilotinib exposure and major molecular response at 12 months was seen at therapeutic doses of nilotinib 300-400 mg, probably due to the narrow range of the doses investigated.

A phase 4 study of nilotinib in Korean patients with Philadelphia chromosome-positive chronic myeloid leukemia in chronic phase: ENESTKorea

Although nilotinib has improved efficacy compared to imatinib, suboptimal response and intolerable adverse events (AEs) limit its effectiveness in many patients with chronic myeloid leukemia in chronic phase (CML-CP). We investigated the 2-year efficacy and safety of nilotinib and their relationships with plasma nilotinib concentrations (PNCs). In this open-label, multi-institutional phase 4 study, 110 Philadelphia chromosome-positive CML-CP patients were treated with nilotinib at a starting dose of 300 mg twice daily. Molecular responses (MRs) and AEs were monitored for up to 24 months. The 24-month cumulative MR^4.5 rate was evaluated as the primary endpoint. Plasma samples were collected from 94 patients to determine PNCs, and the per-patient mean was used to categorize them into four mean PNC (MPNC) groups. Cumulative MR rates and safety were compared between groups. With a median follow-up of 22.2 months, the 24-month cumulative MR^4.5 rate was 56.2% (95% confidence interval, 44.0%-8.3%), and the median time to MR^4.5 was 23.3 months. There were no significant differences in the cumulative rates of major molecular response, MR⁴ , and MR^4.5 between MPNC groups. One patient died due to acute viral hepatitis, and two developed hematological or cytogenetic relapse, while no progression to accelerated or blast phase was observed. Safety results were consistent with previous studies with no new safety signal identified. Across the MPNC groups, there was no significant linear trend in the frequency of AEs. Nilotinib is highly effective for the treatment of CML-CP with manageable AEs. The measurement of PNC has no predictive value for patient outcomes and is thus not found to be clinically useful. This study is registered with clinicaltrials.gov, Number NCT03332511.

Identification of galectin-1 as a novel mediator for chemoresistance in chronic myeloid leukemia cells

Multidrug resistance protein-1 (MDR1) has been proven to be associated with the development of chemoresistance to imatinib (Glivec, STI571) which displays high efficacy in treatment of BCR-ABL-positive chronic myelogenous leukemia (CML). However, the possible mechanisms of MDR1 modulation in the process of the resistance development remain to be defined. Herein, galectin-1 was identified as a candidate modulator of MDR1 by proteomic analysis of a model system of leukemia cell lines with a gradual increase of MDR1 expression and drug resistance. Coincidently, alteration of galectin-1 expression triggers the change of MDR1 expression as well as the resistance to the cytotoxic drugs, suggesting that augment of MDR1 expression engages in galectin-1-mediated chemoresistance. Moreover, we provided the first data showing that NF-κB translocation induced by P38 MAPK activation was responsible for the modulation effect of galectin-1 on MDR1 in the chronic myelogenous leukemia cells. Galectin-1 might be considered as a novel target for combined modality therapy for enhancing the efficacy of CML treatment with imatinib.

Nilotinib induces ER stress and cell death in H9c2 cells

Tyrosine kinases inhibitors (TKi) represent a relatively novel class of anticancer drugs that target cellular pathways overexpressed in certain types of malignancies, such as chronic myeloid leukaemia (CML). Nilotinib, ponatinib and imatinib exhibit cardiotoxic and vascular effects. In this study, we focused on possible cardiotoxicity of nilotinib using H9c2 cells as a suitable cell model. We studied role of endoplasmic reticulum (ER) stress and apoptosis in nilotinib toxicity using a complex approach. Nilotinib impaired mitochondrial function and induced formation of ROS under clinically relevant concentrations. In addition, ability of nilotinib to induce ER stress has been shown. These events result in apoptotic cell death. All these mechanisms contribute to cytotoxic effect of the drug. In addition, involvement of ER stress in nilotinib toxicity may be important in co-treatment with pharmaceuticals affecting ER and ER stress, e.g. beta-blockers or sartans, and should be further investigated.

European LeukemiaNet recommendations for the management and avoidance of adverse events of treatment in chronic myeloid leukaemia

Most reports on chronic myeloid leukaemia (CML) treatment with tyrosine kinase inhibitors (TKIs) focus on efficacy, particularly on molecular response and outcome. In contrast, adverse events (AEs) are often reported as infrequent, minor, tolerable and manageable, but they are increasingly important as therapy is potentially lifelong and multiple TKIs are available. For this reason, the European LeukemiaNet panel for CML management recommendations presents an exhaustive and critical summary of AEs emerging during CML treatment, to assist their understanding, management and prevention. There are five major conclusions. First, the main purpose of CML treatment is the antileukemic effect. Suboptimal management of AEs must not compromise this first objective. Second, most patients will have AEs, usually early, mostly mild to moderate, and which will resolve spontaneously or are easily controlled by simple means. Third, reduction or interruption of treatment must only be done if optimal management of the AE cannot be accomplished in other ways, and frequent monitoring is needed to detect resolution of the AE as early as possible. Fourth, attention must be given to comorbidities and drug interactions, and to new events unrelated to TKIs that are inevitable during such a prolonged treatment. Fifth, some TKI-related AEs have emerged which were not predicted or detected in earlier studies, maybe because of suboptimal attention to or absence from the preclinical data. Overall, imatinib has demonstrated a good long-term safety profile, though recent findings suggest underestimation of symptom severity by physicians. Second and third generation TKIs have shown higher response rates, but have been associated with unexpected problems, some of which could be irreversible. We hope these recommendations will help to minimise adverse events, and we believe that an optimal management of them will be rewarded by better TKI compliance and thus better CML outcomes, together with better quality of life.

Therapeutic drug monitoring of imatinib, nilotinib, and dasatinib for patients with chronic myeloid leukemia

Imatinib, nilotinib, and dasatinib are tyrosine kinase inhibitors (TKIs) that have become first-line treatments for Philadelphia chromosome-positive chronic myeloid leukemia (CML). According to European LeukemiaNet recommendations, the clinical response of CML patients receiving TKI therapy should be evaluated after 3, 6, and 12 months. For patients not achieving a satisfactory response within 3 months, the mean plasma concentration for the three months of TKI administration must be considered. In TKI therapy for CML patients, therapeutic drug monitoring is a new strategy for dosage optimization to obtain a faster and more effective clinical response. The imatinib plasma trough concentration (C₀) should be set above 1000 ng/mL to obtain a response and below 3000 ng/mL to avoid serious adverse events such as neutropenia. For patients with a UGT1A1*6/*6, *6/*28, or *28/*28 genotype initially administered 300-400 mg/d, a target nilotinib C₀ of 500 ng/mL is recommended to prevent elevation of bilirubin levels, whereas for patients with the UGT1A1*1 allele initially administered 600 mg/d, a target nilotinib C₀ of 800 ng/mL is recommended. For dasatinib, it is recommended that a higher Cmax or C₂ (above 50 ng/mL) to obtain a clinical response and a lower C₀ (less than 2.5 ng/mL) to avoid pleural effusion be maintained by once daily administration of dasatinib. Although at present clinicians consider the next pharmacotherapy from clinical responses (efficacy/toxicity) obtained by a fixed dosage of TKI, the TKI dosage should be adjusted based on target plasma concentrations to maximize the efficacy and to minimize the incidence of adverse events.

Safe handling of oral antineoplastic medications: Focus on targeted therapeutics in the home setting

Introduction With the growing number of oral targeted therapies being approved for use in cancer therapy, the potential for long-term administration of these drugs to cancer patients is expanding. The use of these drugs in the home setting has the potential to expose family members and caregivers to them either through direct contact with the drugs or indirectly by exposure to the parent compounds and/or their active metabolites in contaminated patients' waste. Methods A systematic literature review was performed and the known adverse health effect of 32 oral targeted therapeutics is summarized. In particular, the carcinogenicity, genotoxicity, and embryo-fetal toxicity, along with the route of excretion were evaluated. Results Carcinogenicity testing has not been performed on most of the oral targeted therapeutics and the genotoxicity data are mixed. However, the majority of these drugs exhibit adverse reproductive effects, some of which are severe. Currently, available data does not permit the possibility of a health hazard from inappropriate handling of drugs and contaminated patients waste to be ignored, especially in a long-term home setting. Further research is needed to understand these issues. Conclusions With the expanding use of targeted therapies in the home setting, family members and caregivers, especially those of reproductive risk age, are, potentially at risk. Overall basic education and related precautions should be taken to protect family members and caregivers from indirect or direct exposure from these drugs. Further investigations and discussion on this subject are warranted.

A combination of sorafenib and nilotinib reduces the growth of castrate-resistant prostate cancer

Castrate-resistant prostate cancer (CRPC) remains incurable due to the lack of effective therapies. Several tyrosine kinases have been implicated in the development and growth of CRPC, as such targeting these kinases may offer an alternative therapeutic strategy. We established the combination of two tyrosine kinase inhibitors (TKIs), sorafenib and nilotinib, as the most cytotoxic. In addtion, to improve their bioavailability and reduce their metabolism, we encapsulated sorafenib and nilotinib into styrene-co-maleic acid micelles. The micelles' charge, size, and release rate were characterized. We assessed the effect of the combination on the cytotoxicity, cell cycle, apoptosis, protein expression, tumor spheroid integrity, migration, and invasion. The micelles exhibited a mean diameter of 100 nm, a neutral charge, and appeared highly stable. The micellar TKIs promoted greater cytotoxicity, decreased cell proliferation, and increased apoptosis relative to the free TKIs. In addition, the combination reduced the expression and activity of several tyrosine kinases and reduced tumor spheroid integrity and metastatic potential of CRPC cell lines more efficiently than the single treatments. The combination increased the therapeutic potential and demonstrated the relevance of a targeted combination therapy for the treatment of CRPC. In addition, the efficacy of the encapsulated drugs provides the basis for an in vivo preclinical testing.

Symptomatic Acute Pancreatitis Induced by Nilotinib: A Report of Two Cases

Nilotinib is a selective tyrosine kinase inhibitor for the treatment of Philadelphia chromosome-positive leukemias. An elevation of the pancreatic enzyme level is one of the major adverse events associated with nilotinib, but whether or not nilotinib induces symptomatic pancreatitis remains to be elucidated. The cases of two chronic myeloid leukemia patients treated with nilotinib who developed symptomatic acute pancreatitis on the third and fifth day of nilotinib administration are herein presented. Since both patients had no other etiologies for pancreatitis, nilotinib was considered to be the causal agent. The withdrawal of nilotinib resulted in a prompt recovery. These cases underline the importance of recognizing pancreatitis as a possible adverse event associated with nilotinib.

Cardiac QTc interval characteristics before and after hematopoietic stem cell transplantation: an analysis of 995 consecutive patients at a single center

Hematopoietic stem cell transplantation (HSCT) treats disorders affecting patients of all ages. We studied the rate-corrected cardiac QT interval (QTc) in 995 consecutive children and adults undergoing HSCT at the University of Minnesota. We sought to (1) describe QTc before and after HSCT; (2) describe the change in QTc after HSCT; (3) identify factors affecting QTc and its change; and (4) scrutinize an 'at risk' sub-cohort with a long QTc before HSCT. Pre HSCT: 952 (96%) patients had an evaluable electrocardiography (ECG); median QTc was 426 ms and depended upon disease necessitating transplant. Post HSCT: 506 (51%) patients had an evaluable ECG; median QTc was 441 ms. Intrapatient QTc change: 490 (49%) evaluable patients showed median QTc change (pre to post HSCT) of +16 ms (P<0.0001). At risk group: 68 patients were 'at risk' (long pre-HSCT QTc). In some, 'at-risk' status trended toward predictive of post-transplant nonrelapse mortality. QTc interval prolongation is evident in a large, diverse cohort undergoing HSCT at our institution. Prospective studies of this patient population may be warranted, particularly for 'at-risk' patients who demonstrate significant QTc prolongation both pre and post HSCT.

Influence of UGT1A1 6, 27, and 28 polymorphisms on nilotinib-induced hyperbilirubinemia in Japanese patients with chronic myeloid leukemia

Nilotinib potently inhibits human uridine diphosphate-glucuronosyltransferase (UGT1A1) activity, causing hyperbilirubinemia. We investigated the influence of UGT1A1 polymorphisms and nilotinib plasma trough concentrations (C0) on nilotinib-induced hyperbilirubinemia in 34 Japanese patients with chronic myeloid leukemia (CML). The proportion of patients with hyperbilirubinemia was significantly higher among patients with the UGT1A1*6/*6 and *6/*28 genotypes (poor metabolizers) than among those with other genotypes (p = 0.004). The median time to elevation of bilirubin levels in UGT1A1 poor metabolizers was 2.0 weeks (hazard ratio, 6.11). The median time to reduction in nilotinib dose in UGT1A1 poor metabolizers was 4.0 weeks (hazard ratio, 7.52; p = 0.002). Consequently, in the maintenance phase 3 months following the initiation of nilotinib therapy, the median daily dose and C0 of nilotinib were 350 mg/day and 372 ng/mL, respectively, in UGT1A1 poor metabolizers, and 600 mg/day and 804 ng/mL, respectively, in the other patients. Patients at increased hyperbilirubinemia risk could be identified by prospective UGT1A1 genotyping prior to nilotinib therapy. To avoid an interruption of CML treatment due to nilotinib-induced hyperbilirubinemia, it may be beneficial to reduce the initial nilotinib dose to 300-400 mg/day for UGT1A1 poor metabolizers.

Potential interactions between HIV drugs, ritonavir and efavirenz and anticancer drug, nilotinib--a study in primary cultures of human hepatocytes that is applicable to HIV patients with cancer

Nilotinib is used to treat chronic myeloid leukemia (CML), and is metabolized by CYP3A. With a black-box warning for QT prolongation, which is exposure dependent, controlling for drug interactions is clinically relevant. Treatments of HIV patients with CML are with HAART drugs, ritonavir and efavirenz, may cause complex drug interactions through CYP3A inhibition or induction. We evaluated the interactions of ritonavir or efavirenz on nilotinib using human hepatocytes and compared these interactions with those of ketoconazole or rifampin, classical CYP3A inhibitor and inducer, respectively. Hepatocytes were treated with vehicle, ritonavir (10 μM), ketoconazole (10 μM), efavirenz (10 μM), or rifampin (10 μM) for 5 days. On day 5, nilotinib (3 μM) was coincubated for an additional 24-48 hours. The concentrations of nilotinib were quantitated in collected samples (combined lysate and medium) by LC-MS. Apparent intrinsic clearance (CL(int,app)) of nilotinib was lowered 5.8- and 3.1-fold, respectively, by ritonavir and ketoconazole. Efavirenz and rifampin increased the CL(int,app) of nilotinib by 2.1- and 4.1-fold, respectively. The clinically recommended dose (300 mg twice daily) of nilotinib may have to be reduced substantially (150 mg once daily) or increased (400 mg thrice daily), respectively, to achieve desired drug exposure, when ritonavir or efavirenz is co-administered.

Chemotherapy and QT Prolongation: Overview With Clinical Perspective

OPINION STATEMENT

Cardiotoxic adverse events are of concern to physicians treating cancer patients; they are encountered with a variety of agents. Cardiac events may delay the approval of new drugs or impose burdensome monitoring requirements as either part of the pre-approval process or in the daily use of these agents. Among the cardiac issues are the development of QT prolongation and the fear of torsades de pointes (TdP), an unusual yet potentially fatal form of ventricular tachycardia associated with QT prolongation. Several risk factors, including electrolyte imbalance and polypharmacy with concomitant QT prolonging agents use can increase the risk of TdP in cancer patients; separating the individual contributions of the various triggers for TdP remains problematic. Understanding the individual risk of QT prolongation associated with particular chemotherapies can better differentiate between those shown to have higher risk vs. those with lower risk potential. Cardiac monitoring and electrocardiogram analysis require recognition of the common challenges with regard to the precise measurement of the QT interval such as the presence of U waves, intraventricular conduction delays, and heart rate correction. Rapid identification and treatment of QT prolongation and TdP is critical in mitigating the risk of sudden cardiac death in cancer patients. A multidisciplinary treatment approach among cardiologists and oncologists should be employed to help facilitate an appropriate balance between oncologic efficacy and adverse cardiac events.

Clinical pharmacokinetics of tyrosine kinase inhibitors: implications for therapeutic drug monitoring

The treatment of many malignancies has been improved in recent years by the introduction of molecular targeted therapies. These drugs interact preferentially with specific targets that are mutated and/or overexpressed in malignant cells. A group of such targets are the tyrosine kinases, against which a number of inhibitors (tyrosine kinase inhibitors, TKIs) have been developed. Imatinib, a TKI with targets that include the breakpoint cluster region-Abelson (bcr-abl) fusion protein kinase and mast/stem cell growth factor receptor kinase (c-Kit), was the first clinically successful drug of this type and revolutionized the treatment and prognosis of chronic myeloid leukemia and gastrointestinal stromal tumors. This success paved the way for the development of other TKIs for the treatment of a range of hematological malignancies and solid tumors. To date, 14 TKIs have been approved for clinical use and many more are under investigation. All these agents are given orally and are substrates of a range of drug transporters and metabolizing enzymes. In addition, some TKIs are capable of inhibiting their own transporters and metabolizing enzymes, making their disposition and metabolism at steady-state unpredictable. A given dose can therefore give rise to markedly different plasma concentrations in different patients, favoring the selection of resistant clones in the case of subtherapeutic exposure, and increasing the risk of toxicity if dosage is excessive. The aim of this review was to summarize current knowledge of the clinical pharmacokinetics and known adverse effects of the TKIs that are available for clinical use and to provide practical guidance on the implications of these data in patient management, in particular with respect to therapeutic drug monitoring.

ENESTnd trial: a Phase III study comparing nilotinib with imatinib as front-line therapy of early chronic-phase chronic myeloid leukemia

SUMMARY: 

The ENESTnd trial is a Phase III, randomized, open-label, multicenter trial, in which 846 patients with newly diagnosed chromosome Philadelphia-positive chronic-phase chronic myeloid leukemia were randomly assigned in a 1:1:1 ratio between three arms of treatment: imatinib mesylate 400 mg once daily, nilotinib 300 mg twice daily (b.i.d.), nilotinib 400 mg b.i.d. Nilotinib appeared superior to imatinib in terms of complete cytogenetic response at 12 months (77 vs 87 vs 85%; p < 0.001); major molecular response at 12 months (primary end point; BCR–ABL1 on an International Scale < 0.1%: 22 vs 44 vs 43%; p < 0.001); deep response at 4 years (BCR–ABL1IS< 0.0032%: 23 vs 40 vs 37%; p < 0.0001). Less progression to advanced phases at 4 years (0.7 vs 1.1 vs 4.2% on core treatment) converted into a slight advantage in terms of overall survival at 4 years for the nilotinib 400 mg b.i.d. arm in Sokal intermediate- and high-risk patients. Tolerance and quality of life were in favor of nilotinib, with the noteworthy exception of cardiovascular events (1.5 vs 6.4vs 8.7% at 4 years). This trial led to the approval of nilotinib 300 mg b.i.d. as front-line therapy of chronic-phase chronic myeloid leukemia in 2010.

Identifying the time to change BCR-ABL inhibitor therapy in patients with chronic myeloid leukemia

Many patients newly diagnosed with chronic myeloid leukemia in the chronic phase (CML-CP) respond to imatinib. Those experiencing imatinib resistance/intolerance require alternative treatments. Delayed responses increase the risk of transformation to advanced disease, mutation development and loss of response. In retrospective analyses, achieving faster, deeper responses correlated with improved long-term response and outcome. Changing therapy to obtain early responses may improve the depth and speed of response, ultimately improving the outcome. Although trials are ongoing, there are no prospective data indicating that changing from imatinib to later-generation inhibitors reverses the inferior prognosis and improves the outcome. We describe the rationale behind early therapy change in CML-CP.

Comparing nilotinib with dasatinib as second-line therapies in patients with chronic myelogenous leukemia resistant or intolerant to imatinib -- a retrospective chart review analysis

INTRODUCTION

This study compared progression, progression-free survival (PFS), overall survival (OS), and treatment changes among chronic myelogenous leukemia patients in chronic phase (CML-CP) receiving nilotinib or dasatinib as second-line therapy.

PATIENTS AND METHODS

Information on CML-CP patients switched from imatinib to nilotinib or dasatinib as second-line therapy was collected retrospectively from 122 US hematologists and oncologists through an online medical chart review. Progression, PFS, and OS were compared using multivariate Cox proportional hazard models, and treatment changes using chi-square tests.

RESULTS

Of 597 imatinib resistant or intolerant patients, 301 initiated nilotinib and 296 dasatinib as second-line therapy. Nilotinib was associated with a lower risk of progression (hazard ratio [HR] = 0.27; p = 0.021) and longer PFS (HR = 0.48; p = 0.030) than dasatinib, with a median follow-up time of 11 months for nilotinib and 10 months for dasatinib. Nilotinib patients had a lower estimated hazard of mortality than dasatinib patients, though not statistically significant (HR = 0.46; p = 0.067). When treatment changes were classified by the physicians' justifications, fewer nilotinib patients had treatment changes due to ineffectiveness (2.0% vs. 5.1%, p = 0.041) or drug holidays due to intolerance (0.0% vs. 1.7%, p = 0.024) than dasatinib patients.

CONCLUSIONS

Among CML-CP patients in this retrospective chart review who switched from imatinib to either nilotinib or dasatinib, nilotinib was associated with a significantly lower risk of progression and longer PFS than dasatinib. Nilotinib patients were also less likely than dasatinib patients to subsequently have treatment changes due to ineffectiveness or drug holidays due to intolerance. These findings could be subject to unobserved confounders.

Can P-glycoprotein mediate resistance to nilotinib in human leukaemia cells?

The effect of P-glycoprotein (P-gp, ABCB1, MDR1) expression on cell resistance to nilotinib was studied in human leukaemia cells. We used K562/Dox cells overexpressing P-gp and their variants (subclones) with a gradually decreased P-gp expression. These subclones were established by stable transfection of K562/Dox cells with a plasmid vector expressing shRNA targeting the ABCB1 gene. Functional analysis of P-gp using a specific fluorescent probe indicated gradually decreased dye efflux which was proportional to the P-gp expression. We observed that K562/Dox cells overexpressing P-gp contained a significantly reduced intracellular level of nilotinib when compared to their counter partner K562 cells, which do not express P-gp. This effect was accompanied by a decreased sensitivity of the K562/Dox cells to nilotinib. Importantly, cells with downregulated expression of P-gp gradually lost their ability to decrease the intracellular level of nilotinib although they still significantly decreased the intracellular level of daunorubicin (DNR). Accordingly, cells with the reduced expression of P-gp concomitantly failed to provide resistance to nilotinib, however, they exhibited a significant resistance to DNR. Taken together, we demonstrated that the conclusion as to whether P-gp is involved in nilotinib resistance or not strongly depends on its expression at protein level.

Nilotinib-associated vascular events

Anecdotal evidence suggests that nilotinib therapy may be associated with severe peripheral artery occlusive disease (PAOD). The authors describe the experience at M.D. Anderson Cancer Center regarding vascular events associated with nilotinib therapy in patients with chronic myeloid leukemia. Overall, 5 cases of PAOD were identified among 233 patients, for an incidence of 2%. Nilotinib is a highly selective inhibitor of the inactive conformation of ABL1 kinase. An improved topologic fit to the ABL1 protein-binding surface contributes to its increased potency over imatinib. This higher selectivity in vitro translated to an improved tolerability in vivo. In fact, nilotinib therapy in the frontline phase III ENESTnd (Evaluating Nilotinib Efficacy and Safety in Clinical Trials-Newly Diagnosed Patients) study was associated with an improved toxicity profile compared with that of imatinib. Intriguingly, several cases of severe peripheral artery occlusive disease (PAOD) have been reported among patients treated with nilotinib in small series. We have identified 5 patients with chronic myeloid leukemia (CML) in whom vascular events developed that were likely related to nilotinib therapy among 233 (2%) patients treated at our institution: 1 patient had recurrent Raynaud syndrome, a second patient had recurrent cerebrovascular accidents, and 3 other patients had PAOD (2 of them with other vascular events, including coronary artery disease and pulmonary emboli, respectively). Risk factors for vascular disease were present in only 1 patient with a history of diabetes mellitus. Although the incidence of vascular events is low, this potential complication should be taken into account when selecting nilotinib for the treatment of CML.

Advances in treatment of chronic myeloid leukemia with tyrosine kinase inhibitors: the evolving role of Bcr–Abl mutations and mutational analysis

Over the last decade, the treatment of chronic myeloid leukemia has progressed tremendously. The first-generation tyrosine kinase inhibitor imatinib is now flanked by two second-generation molecules, dasatinib and nilotinib – and others are in advanced clinical development. One of the reasons for such intensive research on novel compounds is the problem of resistance, that is thought to be caused, in a proportion of cases, by point mutations in Bcr–Abl. In this article, the authors review how the biological and clinical relevance of Bcr–Abl mutations has evolved in parallel with the availability of more and more therapeutic options. The authors also discuss the practical relevance of Bcr–Abl mutation analysis and how this tool should best be integrated in the optimal clinical management of chronic myeloid leukemia patients.

Chronic myelogenous leukemia: role of stem cell transplant in the imatinib era

In the pre-tyrosine kinase (TKI) era, allogeneic stem cell transplant (allo-SCT) was the front-line treatment of choice for young patients with chronic myelogenous leukemia (CML). Today, imatinib is well established as front-line therapy for CML, with excellent long-term outcomes. This has changed the role of allo-SCT and the number of patients undergoing allo-SCT has declined dramatically. Allo-SCT is currently recommended for patients in accelerated/blast phase disease, those who have failed a second-generation TKI and those with TKI-resistant mutations such as T315I. The role of allo-SCT in the management of CML will require continual reappraisal as medical therapies continue to evolve.