A simplified method for bortezomib determination using dried blood spots in combination with liquid chromatography/tandem mass spectrometry.

Bortezomib, a proteinase inhibitor currently used to treat multiple myeloma and mantle cell lymphoma, has a high incidence of adverse reactions and large inter-individual differences in plasma concentrations. A simple, validated LC-MS/MS method for the quantitative analysis of bortezomib in dried blood spot (DBS) samples was developed to provide support for determining the effective concentration range of bortezomib for clinical use. Fifty (i50) µL of spiked blood were added onto Whatman protein saver cards to prepare the DBS samples. Circular cards of 6 mm diameter were punched, extracted by methanol containing the internal standard (apatinib), and injected into the LC-MS/MS system. The method validation included selectivity, linearity, accuracy and precision, stability, matrix effect, recovery and hematocrit. The calibration curve showed correlation coefficient values higher than 0.999 in the range of 0.2 - 20.0 ng/mL for bortezomib. The acceptance criteria of accuracy (relative error < 12.5%) and precision (coefficient of variation < 10.7%) were met in all cases. The matrix effect was<13.2%, and the recovery was between 87.3 and 100.2%. DBS samples were shown to be stable when stored in cold conditions or at room temperature. Different hematocrit values did not significantly affect the accuracy of the measured concentrations. And there are no significant differences between bortezomib concentrations in DBS samples and plasma samples. This new method was successfully used for clinical concentration determinations of bortezomib and can be applied in future therapeutic drug monitoring and pharmacokinetic studies of bortezomib especially in pediatric patients.

Phase I Study of Venetoclax Plus Daratumumab and Dexamethasone, With or Without Bortezomib, in Patients With Relapsed or Refractory Multiple Myeloma With and Without t(11;14).

PURPOSE: Venetoclax is an oral BCL-2 inhibitor with single-agent activity in patients with relapsed or refractory multiple myeloma (RRMM) with t(11;14) translocation. Venetoclax efficacy in RRMM may be potentiated through combination with agents including bortezomib, dexamethasone, and daratumumab. METHODS: This phase I study (NCT03314181) evaluated venetoclax with daratumumab and dexamethasone (VenDd) in patients with t(11;14) RRMM and VenDd with bortezomib (VenDVd) in cytogenetically unselected patients with RRMM. Primary objectives included expansion-phase dosing, safety, and overall response rate. Secondary objectives included further safety analysis, progression-free survival, duration of response, time to progression, and minimal residual disease negativity. RESULTS: Forty-eight patients were enrolled, 24 each in parts 1 (VenDd) and 2 (VenDVd). There was one dose-limiting toxicity in part 1 (grade 3 febrile neutropenia, 800 mg VenDd). Common adverse events with VenDd and VenDVd included diarrhea (63% and 54%) and nausea (50% and 50%); grade ≥ 3 adverse events were observed in 88% in the VenDd group and 71% in the VenDVd group. One treatment-emergent death occurred in part 2 (sepsis) in the context of progressive disease, with no other infection-related deaths on study with medians of 20.9 and 20.4 months of follow-up in parts 1 and 2, respectively. The overall response rate was 96% with VenDd (all very good partial response or better [≥ VGPR]) and 92% with VenDVd (79% ≥ VGPR). The 18-month progression-free survival rate was 90.5% (95% CI, 67.0 to 97.5) with VenDd and 66.7% (95% CI, 42.5 to 82.5) with VenDVd. CONCLUSION: VenDd and VenDVd produced a high rate of deep and durable responses in patients with RRMM. These results support continued evaluation of venetoclax with daratumumab regimens to treat RRMM, particularly in those with t(11;14).

Pharmacology differences among proteasome inhibitors: Implications for their use in clinical practice.

Preclinical and clinical investigation on proteasome as a druggable target in cancer has led to the development of proteasome inhibitors (PIs) with different pharmacodynamic and pharmacokinetic properties. For example, carfilzomib has a better safety profile and a lower risk of clinically relevant drug-drug interactions than bortezomib, whereas ixazomib can be orally administered on a weekly basis due to a very long elimination half-life and high systemic exposure. The purpose of this review article is to elucidate the quantitative and qualitative differences in potency, selectivity, pharmacokinetics, safety and drug-drug interactions of clinically validated PIs to provide useful information for their clinical use in real life setting.

Bortezomib-loaded lipidic-nano drug delivery systems; formulation, therapeutic efficacy, and pharmacokinetics.

AIM: Nano drug delivery systems can provide the opportunity to reduce side effects and improve the therapeutic aspect of a variety of drugs. Bortezomib (BTZ) is a proteasome inhibitor approved for the treatment of multiple myeloma and mantle cell lymphoma. Severe side effects of BTZ are the major dose-limiting factor. Particulate drug delivery systems for BTZ are polymeric and lipidic drug delivery systems. This review focussed on lipidic-nano drug delivery systems (LNDDSs) for the delivery of BTZ. RESULTS: LNDDSs including liposomes, solid lipid nanoparticles, and self-nanoemulsifying drug delivery systems showed reduce systemic side effects, improved therapeutic efficacy, and increased intestinal absorption. Besides LNDDSs were used to target-delivery of BTZ to cancer. CONCLUSION: Overall, LNDDSs can be considered as a novel delivery system for BTZ to resolve the treatment-associated restrictions.

Phase II, Multicenter, Single-Arm, Open-Label Study to Evaluate the Efficacy and Safety of Panobinostat in Combination with Bortezomib and Dexamethasone in Japanese Patients with Relapsed or Relapsed-and-Refractory Multiple Myeloma.

INTRODUCTION: Panobinostat, bortezomib, and dexamethasone combination therapy demonstrated progression-free survival (PFS) benefit over bortezomib and dexamethasone alone in the PANORAMA-1 study in relapsed/refractory multiple myeloma (MM). Here, we present data from a phase II study (NCT02290431) of this combination in Japanese patients with relapsed or relapsed-and-refractory MM. METHODS: Patients received 3-week cycles of 20-mg oral panobinostat (weeks 1 and 2), 1.3-mg/m2 subcutaneous bortezomib (days 1, 4, 8, and 11), and 20-mg oral dexamethasone (day of and the day following bortezomib administration) for a total of 8 cycles (24 weeks; treatment phase 1). Patients with treatment benefit had an option to enter the extension phase to receive 6-week (42-day) cycles of panobinostat (weeks 1, 2, 4, and 5) plus bortezomib (days 1, 8, 22, and 29) and dexamethasone (day of and the day following bortezomib treatment) for 24 weeks. The primary objective was complete response (CR) + near CR (nCR) rate after treatment phase 1 as per the modified European Society for Blood and Marrow Transplantation criteria. RESULTS: Of the 31 patients, 4 (12.9%) completed the treatment and 27 (87.1%) discontinued; 17 (54.8%) entered the extension phase. In total, 24 patients (77.4%) entered the survival follow-up phase and followed until study closure when the last patient was treated for 1 year after treatment phase 1. The CR + nCR rate was 48.4% (90% CI: 33.6-63.2). The overall response rate (CR + nCR + partial response) was 80.6%. The median PFS, duration of response, time to response, and time to progression were 15.3, 22.7, 1.4, and 15.3 months, respectively. All patients experienced adverse events (AEs), with diarrhea (80.6%), decreased appetite (58.1%), and thrombocytopenia (54.8%) being the most frequent, regardless of relationship to the study treatment. Thrombocytopenia (48.4%), fatigue (25.8%), diarrhea (22.6%), neutrophil count decrease (22.6%), platelet count decrease (22.6%), and lymphocyte count decrease (22.6%) were the most frequent grade 3/4 AEs. CONCLUSION: The study met the primary objective with 48.4% CR + nCR rate. The AEs associated with the combination treatment were safely managed using the existing AE management guidelines, including dose interruption/modification and/or supportive medical intervention. This treatment regimen is an effective option with a favorable benefit/risk profile for Japanese patients with relapsed/refractory MM.

PEGylated Dendrimer Mediated Delivery of Bortezomib: Drug Conjugation versus Encapsulation.

Poor aqueous solubility of anticancer drug bortezomib (BTZ) still remains a major challenge in the development of a successful formulation. The dendrimeric platform can provide a better opportunity to deliver BTZ with improved solubility. BTZ encapsulated in PEGylated PAMAM dendrimers (BTZ-PEG-PAMAM) was characterized and evaluated comparatively with encapsulated and conjugated dendritic formulations. The particle size of BTZ-PEG-PAMAM was 188.6 ± 4.17 nm, with entrapment efficiency of 78.61 ± 2.91% and drug loading of 39.30 ± 1.98%. The aqueous solubility of BTZ in PAMAM-PEG conjugate was enhanced by 68.11 folds in comparison to pure drug. In vitro drug release profile was found to be sustained up to 72 h. A comparative colorimetric MTT assay against A549 and MCF-7 cancer cells resulted in maximum efficacy from BTZ-PEG-PAMAM with IC50 value 333.14 ± 15.42 and 152.60 ± 24.56 nM, respectively. Significantly higher cellular internalization was observed in FITC tagged BTZ-PEG-PAMAM. In vivo pharmacokinetic study performed on Sprague Dawley rats resulted in 8.63 folds increase in bioavailability for BTZ-PEG-PAMAM than pure drug. Pharmacokinetic parameters of BTZ-PEG-PAMAM were better and improved over BTZ and other dendritic formulations. In conclusion, the prepared formulation of BTZ-PEG-PAMAM has given significant outcome and this strategy may be further explored for better delivery of BTZ in future.

A Translational Physiologically Based Pharmacokinetics/Pharmacodynamics Framework of Target-Mediated Disposition, Target Inhibition and Drug-Drug Interactions of Bortezomib.

Bortezomib is a potent 20S proteasome inhibitor approved for the treatment of multiple myeloma and mantle cell lymphoma. Despite the extensive clinical use of bortezomib, the mechanism of the complex time-dependent pharmacokinetics of bortezomib has not been fully investigated in context of its pharmacodynamics (PD) and drug-drug interaction (DDI) profiles. Here, we aimed to develop a mechanistic physiologically based (PB) PK/PD model to project PK, blood target inhibition and DDI of bortezomib in patients. A minimal PBPK/PD model consisting of six compartments was constructed using a bottom-up approach with pre-clinical data and human physiological parameters. Specifically, the target-mediated drug disposition (TMDD) of bortezomib in red blood cells (RBC), which determines target inhibition in blood, was characterized by incorporating the proteasome binding affinity of bortezomib and the proteasome concentration in RBC. The hepatic clearance and fraction metabolized by different CYP isoforms were estimated from in vitro metabolism and phenotyping experiments. The established model adequately characterized the multi-exponential and time-dependent plasma pharmacokinetics, target binding and blood proteasome inhibition of bortezomib. Further, the model was able to accurately predict the impact of a strong CYP3A inducer (rifampicin) and inhibitor (ketoconazole) on bortezomib exposure. In conclusion, the mechanistic PBPK/PD model successfully described the complex pharmacokinetics, target inhibition and DDIs of bortezomib in patients. This study illustrates the importance of incorporating target biology, drug-target interactions and in vitro clearance parameters into mechanistic PBPK/PD models and the utility of such models for pharmacokinetic, pharmacodynamic and DDI predictions.

Bortezomib washout duration prior to stem cell mobilization in patients with newly diagnosed multiple myeloma.

OBJECTIVES: We aimed to determine the impact of washout period in patients with multiple myeloma between bortezomib-based induction regimens and the collection of stem cells. METHODS: This was a single-center historical prospective study, including all sequential newly diagnosed patients with myeloma between 2012 and 2017 that were given a first-line bortezomib-based induction therapy (≤6 cycles) followed by stem cell collection (n = 75). RESULTS: We found a statistically significant correlation between the days from last dose of bortezomib and both CD34+ cells/kg yield on the first collection day and the overall collected CD34+ cells/kg (r = .466, P < .001, and r = .341, P = .03, respectively). The optimal receiver operating curve's cutoff point was 8.5 days (79% sensitivity and 71% specificity, P = .001). On multivariate analysis, timing of last dose of bortezomib remained statistically significant (P = .01). Based on this, we developed a model to predict the total collected CD34+ cells/kg = 11.76 + 0.13 (timing in days of last dose of bortezomib) -0.1 (age) -1.39 (if female) -0.01 (≥PR) -1.35 (if prior radiation). CONCLUSIONS: Timing of last dose of bortezomib may predict a successful collection. A washout period of 9 days is associated with a better collection yield. A prospective validation of this novel finding is required.

Biotinylated HPMA centered polymeric nanoparticles for Bortezomib delivery.

Bortezomib (BTZ) is a proteasome inhibitor as approved by US FDA for the treatment of multiple myeloma. It exhibits significant anti-cancer properties, against solid tumors; but lacks aqueous solubility, chemical stability which hinders its successful formulation development. The present study is an attempt to deliver BTZ using N-(2-hydroxypropyl) methacrylamide (HPMA) based copolymeric conjugates and biotinylated PNPs in an effective manner. Study describes a systematic synthetic pathway to synthesize functional polymeric conjugates such as HPMA-Biotin (HP-BT) HPMA-Polylactic acid (HPLA) and HPMA-PLA-Biotin (HPLA-BT) followed by exhaustive characterization both spectroscopically and microscopically. Our strategy yielded polymeric nanoparticles (PNPs) of narrow size range of 199.7 ± 1.32 nm. Release studies were performed at pH 7.4 and 5.6. PNPs were 2-folds less hemolytic (p < 0.0001) than pure drug. BTZ loaded PNPs of HPLA-BT demonstrated significant anti-cancer activity against MCF-7 cells. IC50 value of these PNPs was 56.06 ± 0.12 nM, which was approximately two folds less than BTZ (p < 0.0001). Cellular uptake study confirmed that higher uptake of formulations might be an outcome of biotin surface tethering characteristics that enhanced selectivity and targeting of formulations efficiently. In vivo pharmacokinetics evidenced increased bioavailability (AUC0 t-∞) of DL-HPLA-BT PNPs (drug loaded) than BTZ with an improved half-life. Overall the developed PNPs led to the improved and effective BTZ delivery.

The Effect of Phase Transition Temperature on Therapeutic Efficacy of Liposomal Bortezomib.

AIMS: Here, three liposomal formulations of DPPC/DPPG/Chol/DSPE-mPEG2000 (F1), DPPC/DPPG/Chol (F2) and HSPC/DPPG/Chol/DSPE-mPEG2000 (F3) encapsulating BTZ were prepared and characterized in terms of their size, surface charge, drug loading, and release profile. Mannitol was used as a trapping agent to entrap the BTZ inside the liposomal core. The cytotoxicity and anti-tumor activity of formulations were investigated in vitro and in vivo in mice bearing tumor. BACKGROUND: Bortezomib (BTZ) is an FDA approved proteasome inhibitor for the treatment of mantle cell lymphoma and multiple myeloma. The low solubility of BTZ has been responsible for the several side effects and low therapeutic efficacy of the drug. Encapsulating BTZ in a nano drug delivery system; helps overcome such issues. Among NDDSs, liposomes are promising diagnostic and therapeutic delivery vehicles in cancer treatment. OBJECTIVE: Evaluating anti-tumor activity of bortezomib liposomal formulations. METHODS: Data prompted us to design and develop three different liposomal formulations of BTZ based on Tm parameter, which determines liposomal stiffness. DPPC (Tm 41°C) and HSPC (Tm 55°C) lipids were chosen as variables associated with liposome rigidity. In vitro cytotoxicity assay was then carried out for the three designed liposomal formulations on C26 and B16F0, which are the colon and melanoma cancer mouse-cell lines, respectively. NIH 3T3 mouse embryonic fibroblast cell line was also used as a normal cell line. The therapeutic efficacy of these formulations was further assessed in mice tumor models. RESULT: MBTZ were successfully encapsulated into all the three liposomal formulations with a high entrapment efficacy of 60, 64, and 84% for F1, F2, and F3, respectively. The findings showed that liposomes mean particle diameter ranged from 103.4 to 146.8nm. In vitro cytotoxicity studies showed that liposomal-BTZ formulations had higher IC50 value in comparison to free BTZ. F2-liposomes with DPPC, having lower Tm of 41°C, showed much higher anti-tumor efficacy in mice models of C26 and B16F0 tumors compared to F3-HSPC liposomes with a Tm of 55°C. F2 formulation also enhanced mice survival compared with untreated groups, either in BALB/c or in C57BL/6 mice. CONCLUSION: Our findings indicated that F2-DPPC-liposomal formulations prepared with Tm close to body temperature seem to be effective in reducing the side effects and increasing the therapeutic efficacy of BTZ and merits further investigation.

Utilization of Lipid-based Nanoparticles to Improve the Therapeutic Benefits of Bortezomib.

Cancer is a condition where there is an uncontrolled growth of cells resulting in high mortality. It is the second most frequent cause of death worldwide. Bortezomib (BTZ) is a Proteasome Inhibitor (PI) that is used for the treatment of a variety of cancers. It is the first PI that has received the approval of the US Food and Drug Administration (FDA) to treat mantle cell lymphoma and multiple myeloma. High incidence of sideeffects, limited dose, low water solubility, fast clearance, and drug resistance are the significant limitations of BTZ. Therefore, various drug delivery systems have been tried to overcome these limitations of BTZ in cancer therapy. Nanotechnology can potentially enhance the aqueous solubility of BTZ, increase its bioavailability, and control the release of BTZ at the site of administration. The lipid-based nanocarriers, such as liposomes, solid lipid NPs, and microemulsions, are some of the developments in nanotechnology, which could potentially enhance the therapeutic benefits of BTZ.

A Semi-Mechanistic Population Pharmacokinetic/Pharmacodynamic Model of Bortezomib in Pediatric Patients with Relapsed/Refractory Acute Lymphoblastic Leukemia.

INTRODUCTION: The pharmacokinetics (PK) of the 20S proteasome inhibitor bortezomib are characterized by a large volume of distribution and a rapid decline in plasma concentrations within the first hour after administration. An increase in exposure was observed in the second week of treatment, which has previously been explained by extensive binding of bortezomib to proteasome in erythrocytes and peripheral tissues. We characterized the nonlinear population PK and pharmacodynamics (PD) of bortezomib in children with acute lymphoblastic leukemia. METHODS: Overall, 323 samples from 28 patients were available from a pediatric clinical study investigating bortezomib at an intravenous dose of 1.3 mg/m2 twice weekly (Dutch Trial Registry number 1881/ITCC021). A semi-physiological PK model for bortezomib was first developed; the PK were linked to the decrease in 20S proteasome activity in the final PK/PD model. RESULTS: The plasma PK data were adequately described using a two-compartment model with linear elimination. Increased concentrations were observed in week 2 compared with week 1, which was described using a Langmuir binding model. The decrease in 20S proteasome activity was best described by a direct effect model with a sigmoidal maximal inhibitory effect, representing the relationship between plasma concentrations and effect. The maximal inhibitory effect was 0.696 pmol AMC/s/mg protein (95% confidence interval 0.664-0.728) after administration. CONCLUSION: The semi-physiological model adequately described the nonlinear PK and PD of bortezomib in plasma. This model can be used to further optimize dosing of bortezomib.

Enhancement of the intestinal absorption of bortezomib by self-nanoemulsifying drug delivery system.

Purpose: Intestinal drug absorption is one of the main factors that govern the fraction of oral dose absorbed (Fa) of drugs. It is reported that oral absorption of bortezomib (BTZ) can be restricted by its low intestinal permeability. In this study, we aimed to evaluate the impact of self-nanoemulsifying drug delivery systems (SNEDDS) on the intestinal absorption and Fa of BTZ.Methods: Intestinal permeability studies were conducted using in situ single-pass intestinal perfusion (SPIP) technique in rats. Human intestinal absorption (Peff (Human)) and Fa values of BTZ and BTZ-SNEDDS were predicted based on SPIP data.Results: Based on the obtained data, Peff (rat) values of (3.36 ± 0.5) × 10-5 and (8.9 ± 3) × 10-5 cm/s (mean ± SEM) were calculated for BTZ and BTZ-SNEDDS, respectively. Meanwhile, Peff (human) values of (7 × 10-5) and (68 × 10-5) cm/sec were predicted for BTZ and BTZ-SNEDDS, respectively. Besides, Fa (human) values of 72.5 and 97% were estimated for BTZ and BTZ-SNEDDS, respectively.Conclusions: According to the obtained data, it is concluded that SNEDDS can be considered as a promising drug delivery system to improve the intestinal absorption and Fa values of BTZ.

IMMUNOGENETIC AND PHARMACOCHEMICAL CHARACTERIZATION OF THE ABO SYSTEM GLYCOPROTEIN PROPERTIES AS CRITERIA OF INDIVIDUAL SENSITIVITY TO ANTITUMOR AGENT BORTEZOMIB IN THE PLASMA CELL MYELOMA PATIENTS. / IMUNOGENETYChNYY̆ TA FARMAKOKhIMIChNYY̆ ANALIZ VLASTYVOSTEY̆ GLIKOPROTEÏNIV SYSTEMY AVO IaK KRYTERIÏV INDYVIDUAL'NOÏ ChUTLYVOSTI ShchODO PROTYPUKhLYNNOGO PREPARATU BORTEZOMIBU U KhVORYKh NA PLAZMOKLITYNNU MIIeLOMU.

OBJECTIVE: Experimental study of the effect profile of bortezomib in the plasma cell myeloma (PCM) patients depend- ing on a specific phenotype carrier state and a pharmacochemical characteristics of ABO system glycoproteins. MATERIALS AND METHODS: The research was conducted on the 104 PCM patients, including the Chornobyl NPP acci- dent survivors (n = 49) and 65 study subjects in the comparison group. Immunogenetic criteria for positive response to the applied treatment protocols were issued according to the duration of remission, absence of infectious com- plications, and evidence of chronic renal failure as a disease complication. RESULTS: Possibility of glycoproteins A and B participation in the formation of human biological individuality at a level of protein-protein interaction with antineoplastic drug bortezomib, which is widely used in cancer management prac- tice, in particular in the PCM treatment is considered. The glycoprotein B was shown being a selective target for borte- zomib, slowing down the recognition and interaction of antigen B with monoclonal anti-B antibody, while the agglu- tination period lengthens at that by 66 %. Assumption that the formation of bortezomib complex with glycoprotein B provides a background for interaction with the key reaction of proteasome 26S inhibition, which to some extent con- tributes to the drug effect retardation was confirmed through the quantum-chemical calculations. Equilibrium is shift- ed toward the main reaction leading to a higher drug efficacy in patients with blood groups O (I) and A (II). CONCLUSIONS: Since the complexation occurs predominantly in alkaline medium the administration of drugs with alkaline reaction should be restricted for at least round the clock after administration of bortezomib according to its half-life in plasma in patients with B (III) blood group and chronic renal failure.

A Sialylated-Bortezomib Prodrug Strategy Based on a Highly Expressed Selectin Target for the Treatment of Leukemia or Solid Tumors.

PURPOSE: This study aimed to explore the potential of sialic acid - related selectin targeting strategy in the treatment of leukemia and some solid tumors. We expected it could "actively" bind tumor cells and kill them, reducing non-specific toxicity to normal cells. METHODS: BOR-SA prodrug was synthesized by reacting an ortho-dihydroxy group in SA with a boronic acid group in BOR. Two kinds of leukemia cells (RAW264.7 and HL60 cells), one solid sarcoma cell model (S180 cells) and their corresponding normal cells (monocytes (MO), neutrophil (NE) and fibroblast (L929)) were selected for the in vitro cell experiments (cytotoxicity, cellular uptake, cell cycle and apoptosis experiments). The S180 tumor-bearing Kunming mice model was established for anti-tumor pharmacodynamic experiments. RESULTS: In vitro cell assay results showed that uptake of BOR-SA by HL60 and S180 cells were increased compared with the control group. BOR-SA induced a lower IC50, higher ratio of apoptosis and cell cycle arrest of tumor cells. In vivo anti-S180 tumor pharmacodynamics experiments showed that mice in the BOR-SA group had higher tumor inhibition rate, higher body weight and lower immune organ toxicity compared with the control group. CONCLUSIONS: sialic acid-mediated selectin targeting strategy may have great potential in the treatment of related tumors.

Drug release and kinetic models of anticancer drug (BTZ) from a pH-responsive alginate polydopamine hydrogel: Towards cancer chemotherapy.

A pH-sensitive polymeric carrier was developed in this study for local delivery of anticancer drug bortezomib (BTZ) to cancer cells. Our strategy is based on the conjugation of BTZ to polymeric carriers containing catechol groups, which are considered to release BTZ selectively in cancer cells. In this study we used alginate-conjugated polydopamine as a building block polymer. The catechol moiety of polydopamine binds to the boronic acid group of BTZ drug and release the drug molecules in a pH-dependent method. Cancer tissue has acidic environment where BTZ dissociate from the catechol group of polydopamine to control the release of the free drug. Mathematical equation models were used to clarify the mechanism of drug release. The release profile fitted first order with correlation coefficient (R2 = 0.98), the release mechanism was studied using Korsmeyer-Peppas, Higuchi, Hixson-Crowell, and Kopcha models. We revealed the release mechanism follows non-fickian and diffusion was the dominant mechanism while small portion contributed to erosion. The pH-sensitive mechanism controls the release of BTZ in targeted cancer cells, hence developing a novel idea that is applicable in future towards other boronic acid-containing drugs to treat various kinds of health challenges.

Mussel-Derived, Cancer-Targeting Peptide as pH-Sensitive Prodrug Nanocarrier.

In this work, we prepared a novel cancer chemotherapeutic nanocarrier through the self-assembly of a mussel-derived, cancer-targeting peptide with a pH-sensitive conjugation of antitumor drugs. The biomimetic peptide was designed with a fluorescent molecule fluorescein isothiocyanate for imaging, a RGD sequence for cancer-targeting and tetravalent catechol groups for dynamic conjugation of the antitumor drug bortezomib via pH-cleavable boronic acid-catechol esters. Our study demonstrated that the peptide-based prodrug nanocarrier dramatically the enhanced specific cellular uptake and cytotoxicity toward human breast cancer cells in vitro in comparison with free drug and nontargeting control nanoparticles. Likewise, the prodrug nanocarrier showed improved therapeutic efficacy and low systematic toxicity in vivo. Considering highly biomimetic nature of the peptide-based nanocarriers, rapid drug release from the dynamically conjugated prodrugs, and convenience of introducing cancer-targeting activity onto this nanosystem, we believe our work would provide new ideas for the development of intelligent and biocompatible drug delivery systems to improve the chemotherapy efficacy in clinic. Furthermore, the pH-sensitive drug conjugation mechanism on peptide-based nanocarriers would provide a hint for the exploitation of dynamic prodrug strategies and the development of highly biocompatible nanocarriers using biogenic materials, e.g., the proteinogenic nanomaterials decorated with drugs through dynamic covalent chemistry.

A phase I trial of palbociclib plus bortezomib in previously treated mantle cell lymphoma.

In mantle cell lymphoma (MCL), cyclin D1 combines with CDK4/6 to phosphorylate Rb, releasing a break on the G1 to S phase cell cycle. Palbociclib is a specific, potent, oral inhibitor of CDK4/6 capable of inducing a complete, prolonged G1 cell cycle arrest (pG1) in Rb+ MCL cells. The proteasome inhibitor bortezomib is approved by the US Food and Drug Administration for treatment of mantle cell lymphoma. Palbociclib-induced pG1 appears to sensitize MCL cells to killing by low-dose bortezomib, potentially improving its activity and tolerability. We conducted a phase 1 trial of palbociclib plus bortezomib in patients with previously treated MCL (NCT01111188). Patients received palbociclib at 75 mg (dose level 1), 100 mg (dose level 2), or 125 mg (dose levels 3 and 4) on days 1-12 of each 21-day cycle in addition to intravenous bortezomib 1.0 mg/m2 (dose levels 1, 2, 3) or 1.3 mg/m2 (dose level 4) on days 8, 11, 15 and 18. A total of 19 patients with a median age of 64 and an average of 2 prior therapies were enrolled. Two subjects experienced dose limiting toxicity (DLT): thrombocytopenia (dose level 1) and neutropenia (dose level 3). Although no DLTs were seen at dose level 4, all patients required dose delays during cycle 2 due to cytopenias, and the study team decided to stop the trial. Four of 19 patients achieved a clinical response, including one patient with a complete response. Three patients received treatment for more than one year, including one patient receiving single-agent palbociclib for more than 6 years. The combination of palbociclib 125 mg on days 1-12 plus bortezomib 1.0 mg/m2 on days 8, 11, 15, and 18 of a 21-day cycle is feasible and active in previously treated MCL, with the primary toxicity being myelosuppression. The regimen may be worthy of further evaluation in patients with non-blastoid MCL following failure of other newer agents.

Clinical Pharmacokinetics and Pharmacodynamics of Bortezomib.

Proteasome inhibitors disrupt multiple pathways in cells and the bone marrow microenvironment, resulting in apoptosis and inhibition of cell-cycle progression, angiogenesis, and proliferation. Bortezomib is a first-in-class proteasome inhibitor approved for the treatment of multiple myeloma and mantle cell lymphoma after one prior therapy. It is also effective in other plasma cell disorders and non-Hodgkin lymphomas. The main mechanism of action of bortezomib is to inhibit the chymotrypsin-like site of the 20S proteolytic core within the 26S proteasome, thereby inducing cell-cycle arrest and apoptosis. The pharmacokinetic profile of intravenous bortezomib is characterized by a two-compartment model with a rapid initial distribution phase followed by a longer elimination phase and a large volume of distribution. Bortezomib is available for subcutaneous and intravenous administration. Pharmacokinetic studies comparing subcutaneous and intravenous bortezomib demonstrated that systemic exposure was equivalent for both routes; pharmacodynamic parameters of 20S proteasome inhibition were also similar. Renal impairment does not influence the intrinsic pharmacokinetics of bortezomib. However, moderate or severe hepatic impairment causes an increase in plasma concentrations of bortezomib. Therefore, patients with moderate or severe hepatic impairment should start at a reduced dose. Because bortezomib undergoes extensive metabolism by hepatic cytochrome P450 3A4 and 2C19 enzymes, certain strong cytochrome P450 3A4 inducers and inhibitors can also alter the systemic exposure of bortezomib. This article critically reviews and summarizes the clinical pharmacokinetics and pharmacodynamics of bortezomib at various dosing levels and routes of administration as well as in specific patient subsets. In addition, we discuss the clinical efficacy and safety of bortezomib.

Extracellular vesicles of multiple myeloma cells utilize the proteasome inhibitor mechanism to moderate endothelial angiogenesis.

Bone marrow microenvironment is known to support angiogenesis, thus contributing to progression of multiple myeloma (MM). Bortezomib, a proteasome inhibitor (PI) widely used in MM treatment, has anti-angiogenic activity. Extracellular vesicles (EVs), shedding from cell surface, serve as mediators in cell-to-cell communication. We have hypothesized that MM cells (MMCs) treated with bortezomib generate EVs that could diminish angiogenesis, thus limiting MM progression. In the present study, EVs were obtained from MMCs (RPMI-8226), untreated (naïve) or pre-treated with bortezomib. EVs were outlined using NanoSight, FACS, protein arrays and proteasome activity assays. The impact of MMC-EVs on endothelial cell (EC) functions was assessed, employing XTT assay, Boyden chamber and Western blot. A high apoptosis level (annexin V binding 70.25 ± 16.37%) was observed in MMCs following exposure to bortezomib. Compared to naïve EVs, a large proportion of bortezomib-induced EVs (Bi-EVs) were bigger in size (> 300 nm), with higher levels of annexin V binding (p = 0.0043).They also differed in content, presenting with increased levels of pro-inflammatory proteins, reduced levels of pro-angiogenic growth factors (VEGFA, PDGF-BB, angiogenin), and displayed lower proteasome activity. Naïve EVs were found to promote EC migration and proliferation via ERK1/2 and JNK1/2/3 phosphorylation, whereas Bi-EVs inhibited these functions. Moreover, Bi-EVs appeared to reduce EC proteasome activity. EVs released from apoptotic MMCs following treatment with bortezomib can promote angiogenesis suppression by decreasing proliferation and migration of EC. These activities are found to be mediated by specific signal transduction pathways.