A phase 1/2 study of NS-87/CPX-351 (cytarabine and daunorubicin liposome) in Japanese patients with high-risk acute myeloid leukemia.

OBJECTIVES: NS-87/CPX-351 is a dual-drug liposomal encapsulation of cytarabine and daunorubicin. NS-87/CPX-351 exerts antileukemic action by maintaining a synergistic molar ratio of cytarabine to daunorubicin of 5:1 within the liposome while in circulation. Patients with high-risk acute myeloid leukemia (AML), which includes therapy-related AML and AML with myelodysplasia-related changes (AML-MRC), have poorer outcomes than those with other AML. METHODOLOGY: This open-label phase 1/2 (P1/2) study was conducted in 47 Japanese patients aged 60-75 years with newly diagnosed high-risk AML to evaluate the pharmacokinetics, safety, and efficacy of NS-87/CPX-351. RESULTS: In the 6 patients enrolled in the P1 portion, no dose-limiting toxicities (DLTs) were reported, and 100 units/m2 during the induction cycle was found to be acceptable. Cytarabine and daunorubicin had a long half-life in the terminal phase (32.8 and 28.7 h, respectively). In the 35 patients enrolled in the P2 portion, composite complete remission (CRc; defined as complete remission [CR] or CR with incomplete hematologic recovery [CRi]) was achieved in 60.0% (90% CI: 44.7-74.0) of the patients. Adverse events due to NS-87/CPX-351 were well tolerated. OUTCOMES: NS-87/CPX-351 can be considered as a frontline treatment option for Japanese patients with high-risk AML.

Nucleic acid biohybrid nanocarriers with high-therapeutic payload and controllable extended release of daunomycin for cancer therapy.

We have developed a novel, nanosized drug carrier with high-therapeutic payload, controllable release, and the potential for active tumor targeting. It consists of a 15 nm gold nanoparticle with dense surface loading of DNA duplexes. We utilize the natural intercalating behavior of daunomycin to load the drug between DNA base pairs. We obtained a high-therapeutic payload of >1,000 drug molecules per gold nanoparticle (AuNP), one of the highest loadings reported in literature to date. We have engineered unique DNA sequences to control release of daunomycin for over 48 hr and show higher cell death compared to equivalent concentrations of free daunomycin. We have also explored cell internalization mechanisms to identify the pathways by which our gold nanoparticles enter the cell. This nanocarrier is in the ideal size range of 16-100 nm in diameter to utilize the enhanced permeability and retention effect for passive targeting to tumors. Our AuNP platform is effective as a therapeutic drug delivery device and can easily incorporate any aptamer of choice through complementary base pairing. Our work has produced an innovative nanoscale drug-delivery platform potentially leading to personalized cancer therapies through careful selection of aptamers and an adjustable drug release profile.

CPX-351 daunorubicin-cytarabine liposome: a novel formulation to treat patients with newly diagnosed secondary acute myeloid leukemia.

Over the last few years, we assisted to an increasing knowledge about acute myeloid leukemia (AML) pathobiology. However, outcomes remain unsatisfactory particularly for adult patients over 60 years old. Not surprisingly several cases of therapy-related AML (tAML) and secondary AML, both characterized by poorer prognosis, are more common in older population. For several decades initial therapy for AML remained unchanged and typically treatment consisted of an anthracycline combined with continuous infusion of cytarabine for 7 days, the so-called "7+3" standard regimen. The efforts made by the researchers to improve this standard schedule, have led to only modest improvement in the response rate (RR) but no change in overall survival (OS), until the recent evolution seen with new target specific mutation therapies. In 2017, a new liposomal-encapsulated formulation with daunorubicin and cytarabine (CPX-351) was approved by the US Food and Drug Administration for the treatment of newly diagnosed tAML or AML with myelodysplasia-related changes (AML-MRCs). Based on the findings that ratiometric delivery may be more effective than administration of either drug at their maximum tolerated dose (MTD), CPX-351 was designed to deliver a fixed 5:1 molar ratio of the two molecules historically used in the standard "7+3" regimen, cytarabine and daunorubicin respectively. CPX-351 did show improvements of overall survival compared to traditional "7+3" in newly diagnosed secondary and therapy-related AML in adult patients. However, questions remain regarding how to select across AML patient subgroups to maximize the clinical benefit. Possible future directions include evaluating CPX-351 dose intensification, combining this liposomal formulation with targeted therapies and not least important a better understanding about the mechanism of improved responses in tAML and AML-MRC, two entities recognized to be less chemo-sensitive than other hematologic malignancies. In summary, CPX-351 offers finally something new in the landscape of AML therapy. Herein we will review the rationale behind this new drug product development, the main pharmacological characteristics, and discuss the results of clinical trials that led to its FDA approval at first and by EMA in 2018.

Pharmacokinetics, drug metabolism, and tissue distribution of CPX-351 in animals.

CPX-351, a liposomal encapsulation of cytarabine and daunorubicin at a synergistic 5:1 molar ratio, is indicated for adults with newly diagnosed, therapy-related acute myeloid leukemia or acute myeloid leukemia with myelodysplasia-related changes. In preclinical species, this article demonstrated (1) similar release of cytarabine and daunorubicin by CPX-351 in plasma; (2) similar patterns of metabolism of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal cytarabine/daunorubicin combination; (3) prolonged tissue exposure to CPX-351; (4) dramatically different tissue distribution of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal combination (tissue:plasma ratios generally <1 versus >1, respectively); and (5) dramatically lower unbound plasma and tissue concentrations of cytarabine and daunorubicin following administration of CPX-351 versus non-liposomal combination. Together, these results provide insight into the safety profile of CPX-351, as well as mechanisms that drive the improved efficacy observed for CPX-351 versus the conventional 7 + 3 cytarabine/daunorubicin regimen in clinical studies.

Can image analysis provide evidence that lysosomal sequestration mediates daunorubicin resistance?

Altered intracellular distribution of weak base anticancer drugs owing to lysosomal sequestration is one purported mechanism contributing to chemotherapy resistance. This has often been demonstrated with the example of daunorubicin (DNR), chemotherapy with its characteristic red fluorescence used to trace it in cellular compartments. Here we addressed the question whether image analysis of DNR fluorescence can reflect its real intracellular distribution. We observed that the relationship between the intensity of the DNR fluorescence and its concentration in water solutions with or without proteins is far from linear. In contrast, nucleic acids, RNA and DNA in particular, dramatically diminish the DNR fluorescence, however, the intensity was proportional to the amount. Therefore, image analysis reflects the composition of different cell compartments (i.e., the presence of proteins and nucleic acids) rather than the actual concentration of DNR in these compartments. In line with these results, we observed highly fluorescent lysosomes and low fluorescent nucleus in sensitive cancer cells treated with low DNR concentrations, a fluorescence pattern thought to be found only in resistant cancer cells. Importantly, LC/MS/MS analysis of extracts from sensitive cells treated with DNR or DNR in combination with an inhibitor of vacuolar ATPase, concanamycin A, indicated that lysosomal accumulation of DNR increased with increasing extracellular concentration. However, even the highest lysosomal accumulation of DNR failed to reduce its extralysosomal concentration and thus change the cell sensitivity to the drug. In conclusion, our results strongly suggest that DNR fluorescence within cells does not indicate the real drug distribution. Further they suggested that lysosomal sequestration of DNR can hardly contribute to its resistance in cancer cells in vitro.

CPX-351: a nanoscale liposomal co-formulation of daunorubicin and cytarabine with unique biodistribution and tumor cell uptake properties.

Combination regimens are a standard of care for many cancers. However, components of such regimens are typically first developed individually and subsequently combined using strategies to minimize toxicity. Little or no consideration is given to strategies that potentially maximize efficacy. In contrast, CPX-351 (Vyxeos®) is a dual-drug liposomal encapsulation of cytarabine and daunorubicin that was rationally designed to improve efficacy over the traditional 7+3 cytarabine/daunorubicin chemotherapy regimen for patients with acute myeloid leukemia (AML). The notable clinical efficacy of CPX-351 is achieved through maintenance of a synergistic 5:1 molar ratio of cytarabine and daunorubicin within the liposome after intravenous injection. The CPX-351 liposome, which is formulated to contain bilayers of distearoylphosphatidylcholine, distearoylphosphatidylglycerol, and cholesterol at a 7:2:1 molar ratio and remains in a gel phase at body temperature, provides stability without polyethylene glycol, controlled release of cytarabine and daunorubicin, limited systemic drug distribution, and preferential internalization within malignant myeloblasts in the bone marrow via active uptake of liposomes into cytoplasmic vacuoles. Thus, the CPX-351 liposome protects cytarabine and daunorubicin from metabolism and elimination, while overcoming pharmacokinetic differences between the two agents. In clinical studies, these liposome properties markedly increased the elimination half-life of CPX-351 versus free cytarabine and daunorubicin and maintained a synergistic drug ratio for over 24 hrs after administration. Preferential uptake of liposomes by leukemia cells suggests that relatively large amounts of cytarabine and daunorubicin enter malignant cells via liposomes, potentially bypassing P-glycoprotein-based efflux pumps, which are important mediators of chemotherapy resistance, and contribute to the rapid clearance of leukemia cells from the circulation and bone marrow. These pharmacologic advantages, a direct consequence of properties of the encapsulating liposome, may explain the efficacy of CPX-351 in patients with newly diagnosed high-risk/secondary AML and the reduced drug exposure in off-target tissues that contribute to a manageable safety profile.

Daunorubicin-containing CLL1-targeting nanomicelles have anti-leukemia stem cell activity in acute myeloid leukemia.

Patients with acute myeloid leukemia have a very poor prognosis related to a high rate of relapse and drug-related toxicity. The ability of leukemia stem cells (LSCs) to survive chemotherapy is primarily responsible for relapse, and eliminating LSCs is ultimately essential for cure. We developed novel disulfide-crosslinked CLL1-targeting micelles (DC-CTM), which can deliver high concentrations of daunorubicin (DNR) into both bulk leukemia cells and LSCs. Compared to free DNR, DC-CTM-DNR had a longer half-life, increased DNR area under the curve concentration by 11-fold, and exhibited a superior toxicity profile. In patient-derived AML xenograft models, DC-CTM-DNR treatment led to significant decreases in AML engraftment and impairment of secondary transplantation compared to control groups. Collectively, we demonstrate superior anti-LSC/AML efficacy, and preferable pharmacokinetic and toxicity profiles of DC-CTM-DNR compared to free DNR. DC-CTM-DNR has the potential to significantly improve treatment outcomes and reduce therapy-related morbidity and mortality for patients with AML.

A phase 2 study to assess the pharmacokinetics and pharmacodynamics of CPX-351 and its effects on cardiac repolarization in patients with acute leukemias.

PURPOSE: Daunorubicin can induce left ventricular dysfunction and QT interval prolongation. This study assessed the effects of CPX-351, a liposomal encapsulation of cytarabine and daunorubicin, on cardiac repolarization. METHODS: Twenty-six adults with acute leukemia were treated with CPX-351 for 1-2 induction cycles and ≤ 4 consolidation cycles. The primary endpoint was mean change in QTcF from baseline. RESULTS: Mean QTcF changes were < 10 ms at all time points. No clinically meaningful effects on heart rate, QRS interval, PR interval, or QTcB were observed. Estimated mean half-lives for total cytarabine and daunorubicin were > 30 h. Thirteen (50%) patients achieved remission. The most common adverse events were febrile neutropenia, fatigue, and nausea. CONCLUSIONS: The cytarabine and daunorubicin in CPX-351 liposomes were metabolized and excreted similarly to conventional formulation; however, plasma pharmacokinetics were altered. CPX-351 did not prolong the QT interval, suggesting that CPX-351 may induce less cardiotoxicity than previously reported for conventional daunorubicin. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT02238925.

Eltrombopag treatment during induction chemotherapy for acute myeloid leukaemia: a randomised, double-blind, phase 2 study.

BACKGROUND: Patients with acute myeloid leukaemia frequently have thrombocytopenia during induction chemotherapy. Eltrombopag, an oral thrombopoietin receptor agonist, stimulates platelet production by a similar mechanism to endogenous thrombopoietin. This study investigated safety and efficacy of eltrombopag versus placebo during anthracycline-based induction treatment of patients with acute myeloid leukaemia. METHODS: In this randomised, double-blind, phase 2 study, treatment-naive patients were recruited from clinical centres across 10 countries (Australia, Belgium, Canada, Greece, Hungary, Israel, South Korea, Poland, Russia, and the USA). Patients with acute myeloid leukaemia of any subtype except M3 and M7 were stratified by antecedent malignant haematological disorder (yes or no) and age (18-60 years or >60 years) and were then randomly assigned (1:1) using an automated interactive voice-response system randomisation schedule. Investigators and patients were blinded to study treatment. Starting on day 4, patients received standard induction chemotherapy (daunorubicin bolus intravenous infusion on days 1-3 [90 mg/m2 for patients aged 18-60 years or 60 mg/m2 for patients aged >60 years], plus cytarabine continuous intravenous infusion on days 1-7 [100 mg/m2]), with eltrombopag 200 mg (100 mg for east Asians) or placebo once daily, until platelet counts were 200 × 109/L or higher, until remission, or after 42 days from the start of induction chemotherapy. The primary objective of the study was safety and tolerability assessed by adverse events, changes in left ventricular ejection fraction (LVEF), and clinical laboratory parameters in all treated patients. This study has been completed and is registered with ClinicalTrials.gov, number NCT01890746. FINDINGS: Between Sept 7, 2013, and Jan 30, 2015, 149 patients were assessed for eligibility and 148 were then randomly assigned to receive eltrombopag (n=74) and placebo (n=74). Groups were matched in mean (SD) age (56·7 years [12·3] in the eltrombopag group vs 56·6 years [11·6] in the placebo group), mean (SD) initial platelet count (59·5 × 109/L [43·3] vs 63·7 × 109/L [48·0]), and poor-risk karyotype (16 [22%] of 74 patients in both groups). The most common grade 3-4 adverse events (≥10% in either group) were febrile neutropenia (31 [42%] vs 28 [39%]), decreased white blood cell count (8 [11%] vs 5 [7%]), and hypophosphataemia (3 [4%] vs 9 [13%]). Serious adverse events occurred in 24 (32%) patients in the eltrombopag group compared with 14 (20%) patients in the placebo group. 39 (53%) patients in the eltrombopag group died versus 29 (41%) patients in the placebo group. Thromboembolic events (5 [7%] vs 4 [6%]) and mean (SD) change in LVEF (-2·5% [7·8] vs -4·3% [8·5]) were similar. INTERPRETATION: Data from this trial do not support combining eltrombopag with induction chemotherapy in patients with acute myeloid leukaemia. FUNDING: Novartis Pharma AG.

Daunorubicin oral bioavailability enhancement by surface coated natural biodegradable macromolecule chitosan based polymeric nanoparticles.

BACKGROUND: Daunorubicin hydrochloride (DAUN·HCl), due to low oral bioavailability poses the hindrance to be marketed as an oral formulation. AIM OF THE STUDY: To develop a natural biodegradable macromolecule i.e. Chitosan (CS)-coated-DAUN-PLGA-poly(lactic-co-glycolic acid)-Nanoparticles (NPs) with an aim to improve oral-DAUN bioavailability and to develop as well as validate UHPLC-MS/MS (ESI/Q-TOF) method for plasma quantification and pharmacokinetic analysis (PK) of DAUN. RESULTS: A particle size (198.3 ±â€¯9.21 nm), drug content (47.06 ±â€¯1.16 mg/mg) and zeta potential (11.3 ±â€¯0.98 mV), consisting of smooth and spherical shape was observed for developed formulation. Cytotoxicity studies for CS-DAUN-PLGA-NPs revealed; a comparative superiority over free DAUN-S (i.v.) in human breast adenocarcinoma cell lines (MCF-7) and a higher permeability i.e. 3.89 folds across rat ileum, as compared to DAUN-PLGA-NPs (p < 0.01) inhuman colon adenocarcinoma cell line (Caco-2). For PK, CS-DAUN-PLGA-NPs as compared to DAUN-S, exhibited a 10.0 fold higher bioavailability in Wister rat's plasma due to presence of a natural biodegradable macromolecule i.e. CS coated on the PLGA-NPs. With regard to bioanalytical method, easy as well as a rapid method for DAUN-plasma quantification was developed as; 2.75 min and 528.49/321.54 m/z for DAUN along with 1.94 min and 544.36/397.41 m/z for IS i.e. Doxorubicin, for elution time and transition, respectively. CONCLUSION: A novel natural biodegradable approach used in the preparation of CS coated DAUN-NPs for oral administration of DAUN is reported in this study which is can be utilized as an alternate for intravenous therapy.

Population Pharmacokinetics and Exposure-Response Analyses for CPX-351 in Patients With Hematologic Malignancies.

CPX-351, a dual-drug liposomal encapsulation of cytarabine and daunorubicin at a synergistic ratio, is approved in the United States for adults with newly diagnosed therapy-related acute myeloid leukemia or acute myeloid leukemia with myelodysplasia-related changes. Population pharmacokinetics analyses were performed using nonlinear mixed-effect modeling on pooled data from 3 clinical studies, and the impact of CPX-351 exposures on efficacy and safety was assessed. The pharmacokinetics of cytarabine and daunorubicin were described using 2-compartment models with linear elimination. None of the evaluated covariates had a clinically significant impact on plasma exposure to total cytarabine or daunorubicin, while bilirubin and formulation showed statistically significant effects on pharmacokinetic parameters of cytarabine and daunorubicin, respectively. In patients with mild/moderate renal impairment or serum bilirubin ≤3 mg/dL, plasma exposures to cytarabine and daunorubicin following CPX-351 were within the variability range for patients with normal kidney function or serum bilirubin levels. Exposure-response analysis demonstrated that better efficacy outcomes were associated with higher CPX-351 exposure quartiles. Early mortality rates in all CPX-351 exposure quartiles were lower vs the 7 + 3 control group, and lower mortality rates were associated with higher exposure quartiles. A trend toward greater frequency of grade 3 treatment-emergent adverse events (but not grade 4/5 events) was observed at higher CPX-351 exposure quartiles. Overall, the population pharmacokinetic analyses indicate no adjustments to the recommended dose and schedule of CPX-351 are warranted for patients with mild/moderate renal impairment or serum bilirubin ≤3 mg/dL. Results from the exposure-response analyses suggest the current CPX-351 regimen provides a favorable risk-benefit profile.

Experience with generic pegylated L-asparaginase in children with acute lymphoblastic leukemia and monitoring of serum asparaginase activity.

BACKGROUND: Pegylated asparaginase (P-Asp) though integral to acute lymphoblastic leukemia (ALL) therapy is often not accessible to patients in developing countries. We share our clinical experience with generic P-Asp along with monitoring of asparaginase activity. METHODS: In this prospective observational study, patients ≤18 years of age with ALL were assigned to receive either generic P-Asp or native asparaginase (N-Asp) in a non-randomized manner. Treatment protocol was based on ALL BFM-95 backbone. The dose of P-Asp was 1500 IU/m2 by intravenous route during induction (Ia) and re-induction (IIa) phase of therapy. RESULTS: N-Asp or P-Asp was administered to 52 and 54 of the 106 eligible patients respectively. Demographic and disease characteristics were comparable in both arms. The mean trough levels for N-Asp and P-Asp were 156.87 ± 22.35 IU/L and 216.03 ± 73.40 IU/L, respectively (p value <0.001) and all patients achieved therapeutic levels during Ia. Incidence of asparaginase-attributable toxicity was similar in the two arms in both phases of treatment, although hospitalization due to noninfectious causes was more common in P-Asp arm during Ia (13% versus 0%, p value, 0.01). Clinical hypersensitivity and silent inactivation were not observed during Ia while these occurred in 13% and 5% of patients in the N-Asp arm and P-Asp arms of IIa, respectively. The 2-year event free survival for P-Asp and N-Asp groups was 84% and 80.7%, respectively (p value 0.85). CONCLUSION: Generic P-Asp was observed to be efficacious and well tolerated in our patients and adequate therapeutic levels were sustained for 2 weeks.

Development of multi-layered and multi-sensitive polymeric nanocontainers for cancer therapy: in vitro evaluation.

Nanoscale drug delivery systems represent a promising strategy to treat cancer and to overcome the side effects of chemotherapy. In particular, hollow polymeric nanocontainers have attracted great interest because of their structural and morphological advantages and the variety of polymers that can be used, allowing the synthesis of stimuli-responsive materials capable of responding to the biochemical alterations of the tumour microenvironment. Here are reported the synthesis, characterization and in vitro evaluation of a three-stimuli-sensitive hollow nanocontainer consisting of three different shells, each one sensitive to a specific tumoral stimulus: in order pH, temperature and reducing environment. To test its properties, daunorubicin was used as a model drug, for which the nanocontainers exhibited excellent encapsulation ability. The in vitro drug release behaviour was studied under different conditions, where the system proved capable of responding to the selected tumoral stimuli by releasing a larger amount of drug than in physiological environment. The hollow system itself showed negligible cytotoxicity but the loaded nanocontainers and free drug showed identical cytotoxicity and intracellular localization. Therefore, this formulation can be considered as a promising platform to develop an injectable delivery system capable of improving systematic toxicity without affecting or reducing the activity of the encapsulated drug.

CPX-351 exhibits hENT-independent uptake and can be potentiated by fludarabine in leukaemic cells lines and primary refractory AML.

CPX-351, a liposomal formulation co-encapsulating cytarabine and daunorubicin (DNR) in a synergistic 5:1 M ratio, has shown favourable response in newly diagnosed elderly high-risk AML. This study assessed intracellular ara-CTP levels following in vitro exposure of human immortalised leukaemic cell lines and primary AML blasts to CPX-351, and investigated fludarabine potentiation of intracellular ara-CTP formation from CPX-351. Comparison of intracellular handling of CPX-351 to cytarabine in HL-60 cells indicated slower conversion to ara-CTP for CPX-351, but equivalent cytotoxicity to cytarabine and combined DNR/cytarabine (DA) at 48 h, mostly likely reflecting the need for intracellular liposome processing to release encapsulated drugs. Further assessment demonstrated cytotoxicity of CPX-351 to be superior to DA at 48 and 72 h in cytarabine-resistant THP-1 cells (p < 0.001), and this effect could not be inhibited upon blockade of human equilibrative nucleoside transporter (hENT) function with dipyridamole. Assessment of Flu-CPX in primary blasts from presentation AML patients (n = 5) demonstrated a more rapid and pronounced potentiation of ara-CTP from CPX-351 than in immortalised cell lines, with 4/5 patients showing significant increases in ara-CTP, notably for those that went on to fail induction and relapse treatment in vivo (n = 3). This suggests a favourable impact on patient outcome from Flu-CPX.

Extravasation accidents with liposomal/liposomal pegylated anthracyclines treated with dexrazoxane: an overview and outcomes.

The extravasation of chemotherapeutic agents is a challenge for oncologic care teams. The management of nonliposomal (conventional) anthracyclines is well established in clinical practice guidelines, including general measures and specific antidotes, such as dexrazoxane. However, there is little scientific evidence on the management of liposomal and pegylated liposomal anthracyclines. The aim of this paper was to review the scientific literature on the extravasation of liposomal and pegylated liposomal anthracyclines and determine the clinical impact of this type of extravasation, focusing on dexrazoxane. The literature was searched using two databases: PubMed and Embase. Three searches were conducted, using liposomal anthracycline extravasation, pegylated liposomal anthracycline extravasation, and liposomal doxorubicin extravasation as keywords, respectively. Seven articles fulfilled the study eligibility criteria and included seventeen cases in humans. Extravasation occurred with three drugs: liposomal doxorubicin in nine (53%) patients, liposomal daunorubicin in four (23.5%) patients, and pegylated liposomal doxorubicin in four (23.5%) patients. General measures for extravasations were applied in all patients, but only three patients received dexrazoxane. All cases were completely resolved at 2-3 months, except for one patient, in whom dexrazoxane was not used. In animals, dexrazoxane decreased both the frequency of wounds produced by pegylated liposomal doxorubicin and their extent. The pharmacokinetic profiles of liposomal and pegylated liposomal anthracyclines differ from those of conventional anthracyclines, modifying their effectiveness and safety. General measures may be inadequate to heal areas affected by extravasation, which may require the administration of dexrazoxane. However, each case should be evaluated individually for the administration of dexrazoxane in off-label use until scientific evidence is available on its effectiveness and safety as an antidote for these formulations of anthracyclines.

Aldo-keto reductase 1C3 (AKR1C3): a missing piece of the puzzle in the dinaciclib interaction profile.

Dinaciclib is a multi-specific cyclin-dependent kinase (CDK) inhibitor with significant preclinical and clinical activity. It inhibits CDK1, CDK2, CDK5, CDK9 and CDK12 in the nanomolar range and exhibits potent antiproliferative effects on various cancers in vitro and in vivo. Aldo-keto reductases (AKR) and carbonyl reductases (CBR) are enzymes involved at the biosynthesis, intermediary metabolism and detoxification processes, but can also play a significant role in cancer resistance. Here, we report that dinaciclib is a strong inhibitor of aldo-keto reductase 1C3 (AKR1C3), an enzyme that is known to be an important regulator of cell proliferation and differentiation. AKR1C3 is overexpressed in a range of cancer types and is also involved in tumour cell resistance to anthracyclines. In our study, dinaciclib displayed tight-binding inhibition of human recombinant AKR1C3 (Kiapp = 0.07 µM) and was also active at the cellular level (IC50 = 0.23 µM). Dinaciclib acts as a noncompetitive inhibitor with respect to daunorubicin and as an uncompetitive inhibitor with respect to the NADPH. In subsequent experiments, pretreatment with dinaciclib (0.1 µM) significantly sensitized AKR1C3-overexpressing anthracycline-resistant cancer cells to daunorubicin. In conclusion, our results indicate that dinaciclib may potentially increase the therapeutic efficacy and safety of anthracyclines by preventing anthracycline resistance and minimizing their adverse effects.

Clofarabine, high-dose cytarabine and liposomal daunorubicin in pediatric relapsed/refractory acute myeloid leukemia: a phase IB study.

Survival in children with relapsed/refractory acute myeloid leukemia is unsatisfactory. Treatment consists of one course of fludarabine, cytarabine and liposomal daunorubicin, followed by fludarabine and cytarabine and stem-cell transplantation. Study ITCC 020/I-BFM 2009-02 aimed to identify the recommended phase II dose of clofarabine replacing fludarabine in the abovementioned combination regimen (3+3 design). Escalating dose levels of clofarabine (20-40 mg/m2/day × 5 days) and liposomal daunorubicin (40-80 mg/m2/day) were administered with cytarabine (2 g/m2/day × 5 days). Liposomal DNR was given on day 1, 3 and 5 only. The cohort at the recommended phase II dose was expanded to make a preliminary assessment of anti-leukemic activity. Thirty-four children were enrolled: refractory 1st (n=11), early 1st (n=15), ≥2nd relapse (n=8). Dose level 3 (30 mg/m2clofarabine; 60 mg/m2liposomal daunorubicin) appeared to be safe only in patients without subclinical fungal infections. Infectious complications were dose-limiting. The recommended phase II dose was 40 mg/m2 clofarabine with 60 mg/m2 liposomal daunorubicin. Side-effects mainly consisted of infections. The overall response rate was 68% in 31 response evaluable patients, and 80% at the recommended phase II dose (n=10); 22 patients proceeded to stem cell transplantation. The 2-year probability of event-free survival (pEFS) was 26.5±7.6 and probability of survival (pOS) 32.4±8.0%. In the 21 responding patients, the 2-year pEFS was 42.9±10.8 and pOS 47.6±10.9%. Clofarabine exposure in plasma was not significantly different from that in single-agent studies. In conclusion, clofarabine was well tolerated and showed high response rates in relapsed/refractory pediatric acute myeloid leukemia. Patients with (sub) clinical fungal infections should be treated with caution. Clofarabine has been taken forward in the Berlin-Frankfurt-Münster study for newly diagnosed acute myeloid leukemia. The Study ITCC-020 was registered as EUDRA-CT 2009-009457-13; Dutch Trial Registry number 1880.

Persistent cytarabine and daunorubicin exposure after administration of novel liposomal formulation CPX-351: population pharmacokinetic assessment.

PURPOSE: CPX-351 is a novel liposomal formulation of cytarabine and daunorubicin which has recently been FDA approved for treatment of acute myeloid leukemia (AML). The current study investigated the pharmacokinetics (PK) of this liposomal formulation. METHODS: CPX-351 PK data (cytarabine, daunorubicin, and metabolites) from a phase I study of relapsed and refractory AML were used for the analysis. Therapy was given days 1, 3, and 5 of induction (3-134 units/m2). We developed a population PK model to characterize CPX-351 disposition. RESULTS: 39 patients (3589 samples) were evaluated. Liposomal cytarabine and daunorubicin were modeled separately with their respective metabolites. A one-compartment model fit the parent compounds well; the metabolites required two-compartment models. Weight was an independent predictor of liposomal volumes; mild renal and liver dysfunction were not predictors of clearance or volume (maximum creatinine 1.6 mg/dL and total bilirubin 1.8 mg/dL). Liposomal clearances of the two drugs were highly correlated and 1000-fold smaller than published non-encapsulated values supporting prolonged encapsulation in the liposome. CONCLUSIONS: The PK model demonstrates prolonged exposure to cytarabine and daunorubicin without increases in non-hematologic toxicity that indicates retention of the drugs within the liposome. The unique pharmacology of this formulation may allow for simplified regimens and improved outcomes.

A biophysical approach to daunorubicin interaction with model membranes: relevance for the drug's biological activity.

Daunorubicin is extensively used in chemotherapy for diverse types of cancer. Over the years, evidence has suggested that the mechanisms by which daunorubicin causes cytotoxic effects are also associated with interactions at the membrane level. The aim of the present work was to study the interplay between daunorubicin and mimetic membrane models composed of different ratios of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), sphingomyelin (SM) and cholesterol (Chol). Several biophysical parameters were assessed using liposomes as mimetic model membranes. Thereby, the ability of daunorubicin to partition into lipid bilayers, its apparent location within the membrane and its effect on membrane fluidity were investigated. The results showed that daunorubicin has higher affinity for lipid bilayers composed of DMPC, followed by DMPC : SM, DMPC : Chol and lastly by DMPC : SM : Chol. The addition of SM or Chol into DMPC membranes not only increases the complexity of the model membrane but also decreases its fluidity, which, in turn, reduces the amount of anticancer drug that can partition into these mimetic models. Fluorescence quenching studies suggest a broad distribution of the drug across the bilayer thickness, with a preferential location in the phospholipid tails. The gathered data support that daunorubicin permeates all types of membranes to different degrees, interacts with phospholipids through electrostatic and hydrophobic bonds and causes alterations in the biophysical properties of the bilayers, namely in membrane fluidity. In fact, a decrease in membrane fluidity can be observed in the acyl region of the phospholipids. Ultimately, such outcomes can be correlated with daunorubicin's biological action, where membrane structure and lipid composition have an important role. In fact, the results indicate that the intercalation of daunorubicin between the phospholipids can also take place in rigid domains, such as rafts that are known to be involved in different receptor processes, which are important for cellular function.

Synthesis and Characterization of Micelle-Forming PEG-Poly(Amino Acid) Copolymers with Iron-Hydroxamate Cross-Linkable Blocks for Encapsulation and Release of Hydrophobic Drugs.

Described is the development of a polymeric micelle drug delivery platform that addresses the physical property limitations of many nanovectors. The system employs triblock copolymers comprised of a hydrophilic poly(ethylene glycol) (PEG) block, and two poly(amino acid) (PAA) blocks: a stabilizing cross-linking central block, and a hydrophobic drug encapsulation block. Detailed description of synthetic strategies and considerations found to be critical are discussed. Of note, it was determined that the purity of the α-amino acid-N-carboxyanhydrides (NCA) monomers and PEG macroinitiator are ultimately responsible for impurities that arise during the polymerization. Also, contrary to current beliefs in the field, the presence of water does not adversely affect the polymerization of NCAs. Furthermore, we describe the impact of poly(amino acid) conformational changes, through the incorporation of d-amino acids to form mixed stereochemistry PAA blocks, with regard to the physical and pharmacokinetic properties of the resulting micelles.