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Since gaining approval for the treatment of chronic lymphocytic leukemia (CLL), the BCL-2 inhibitor venetoclax has transformed the treatment of this and other blood-related cancers. Reflecting the large and hydrophobic BH3-binding groove within BCL-2, venetoclax has significantly higher molecular weight and lipophilicity than most orally administered drugs, along with negligible water solubility. Although a technology-enabled formulation successfully achieves oral absorption in humans, venetoclax tablets have limited drug loading and therefore can present a substantial pill burden for patients in high-dose indications. We therefore generated a phosphate prodrug (3, ABBV-167) that confers significantly increased water solubility to venetoclax and, upon oral administration to healthy volunteers either as a solution or high drug-load immediate release tablet, extensively converts to the parent drug. Additionally, ABBV-167 demonstrated a lower food effect with respect to venetoclax tablets. These data indicate that beyond-rule-of-5 molecules can be successfully delivered to humans via a solubility-enhancing prodrug moiety to afford robust exposures of the parent drug following oral dosing.

1. Measured pKa values of ABBV-167 (Table S1. Ionization constants of ABBV-167) 2. Preparation of ABBV-167 on large scale (Scheme S1: Synopsis of GMP synthesis of ABBV-167) 3. Preparation of clinical ABBV-167 drug supply 4. Animal pharmacokinetics (Table S2. Single dose pharmacokinetics of prodrug 3 and parent venetoclax in mouse and dog after IV dosing of prodrug 3. Table S3. Single dose pharmacokinetics of 3 after oral dosing in mouse and dog. Table S4. Single dose pharmacokinetics of parent venetoclax in mouse and dog after oral dosing of 3.) 5. Clinical study (Study design, Pharmacokinetic and statistical analysis, Safety and tolerability assessments, Clinical pharmacokinetic results, Table S5. Effect of prodrug and food on venetoclax bioavailability, Safety results) 6. Crystallography methods (Protein preparation. BCL-2 ABBV-167 complex crystallization. X-ray structure determination. Table S6. Diffraction data collection and refinement statistics for BCL-2 in complex with ABBV-167 (PDB code 7LHB))

Since gaining approval for the treatment of chronic lymphocytic leukemia (CLL), the BCL-2 inhibitor venetoclax has transformed the treatment of this and other blood-related cancers. Reflecting the large and hydrophobic BH3-binding groove within BCL-2, venetoclax has significantly higher molecular weight and lipophilicity than most orally administered drugs, along with negligible water solubility. Although a technology-enabled formulation successfully achieves oral absorption in humans, venetoclax tablets have limited drug loading and therefore can present a substantial pill burden for patients in high-dose indications. We therefore generated a phosphate prodrug (3, ABBV-167) that confers significantly increased water solubility to venetoclax and, upon oral administration to healthy volunteers either as a solution or high drug-load immediate release tablet, extensively converts to the parent drug. Additionally, ABBV-167 demonstrated a lower food effect with respect to venetoclax tablets. These data indicate that beyond-rule-of-5 molecules can be successfully delivered to humans via a solubility-enhancing prodrug moiety to afford robust exposures of the parent drug following oral dosing.

Venetoclax is a highly selective, potent BCL-2 inhibitor that is approved for some patients previously treated for chronic lymphocytic leukemia, and has shown promising activity in adult studies across several hematologic malignancies. Preclinical studies have demonstrated venetoclax activity in pediatric patient-derived xenograft models and cell lines; however, clinical studies in pediatric patients have yet to be conducted. The prognosis is poor for children with most relapsed/refractory malignancies, and limited treatment options result in unmet clinical need. Herein, we describe the rationale and design of the first study of venetoclax in pediatric patients with relapsed/refractory malignancies: a Phase I trial investigating the safety and pharmacokinetics of venetoclax monotherapy followed by the addition of chemotherapy (Trial registration: EudraCT 2017-000439-14; NCT03236857).

The objectives of this study were to investigate the effects of manufacturing parameters on the moisture sorption isotherms of some tablet formulations and to predict the moisture isotherms of the final formulations using polynomial equations. Three tablet formulations including a placebo and 2 drug products were prepared through wet granulation, drying, compression, and coating processes. Equilibrium moisture content of excipients and granules at 25 degrees C with different relative humidities were determined using a dynamic moisture sorption microbalance, while such data for tablets were determined using desiccators. Moisture sorption isotherms were expressed in polynomial equations. Excipient isotherms were used to predict the moisture sorption isotherms of the 3 tablet products. Results showed that different physical properties of granules and tablets, such as particle size distribution, density, and porosity resulting from different granulation and compression conditions did not have significant effect on the moisture isotherms of the materials. Changing coating materials from a powder mixture to a film also did not change the moisture sorption characteristics significantly. The predicted moisture sorption isotherms of the formulations agreed well with the experimental results. These results show that moisture isotherms of solid pharmaceutical products manufactured with conventional processes may be predicted using the isotherms of excipients, and polynomial equations may be used as a tool for the prediction of moisture isotherms.

The effect of SBE4-β-CD, a sulfobutyl ether derivative of β-cyclodextrin on the solubility and aqueous hydrolysis of the antitumor drug O6-benzylguanine (BG) was studied. SBE4-β-CD is an apparently parenterally safe anionic β-cyclodextrin derivative with superior solubilizing properties in water. BG has poor aqueous solubility and undergoes rapid hydrolysis to the poorly water soluble guanine. The stability of a parenteral BG formulation was studied after storage at 25, 37 and 50°C. Compared to the intrinsic solubility of BG (0.14 mg/ml, 25°C), 0.05 M SBE4-β-CD enhanced its solubility to 2.9 mg/ml at 25°C and 3.9 mg/ml at 50°C. Solubility data yielded binding constants (Kb) of 565 M−1 at 25°C and 342 M−1 at 50°C. The solubility of guanine was only slightly enhanced by SBE4-β-CD. Hydrolysis kinetics of BG were studied at 50°C over a pH range of 1–9 and the maximum stability was observed at pH 8-8.5. In the presence of 0.05 M SBE4-β-CD, hydrolysis was about 9.5-times slower at pH 1, 14.6-times slower at pH 6 and 10-times slower at pH 8. The effect of SBE4-β-CD concentration was studied at pH 2.2 and 4.8 at 50°C. Hydrolysis rate constants decreased with increasing SBE4-β-CD concentrations. A non-linear regression analysis of this data yielded Kb values of 311 and 270 M−1 at pH 2.2 and 4.8, respectively. A formulation containing 2.5 mg/ml of BG and 0.05 M SBE4-β-CD in a pH 8 phosphate buffer was stored in ampoules at 25, 37 and 50°C. Guanine production in the samples was measured since its low solubility (2.5 μg/ml) imposed a limitation on the shelf life. Guanine levels exceeded its apparent solubility after 1–2 months of storage at 50°C. At 37°C guanine levels were only 1.6 μg/ml after 343 days of storage whereas those at 25°C were negligible and below the limit of quantitation (approx. 0.1 μg/ml). The greater stability at room temperature may be attributed to the higher Kb value observed and greater intrinsic stability of BG in the complex.

Hyaluronic acid benzyl ester films were studied for ocular delivery of prednisolone. The four polymers used were HYAFF 11 p25 (25% benzyl ester, 75% sodium salt), HYAFF 11 p50 (50% benzyl ester, 50% sodium salt), HYAFF 11 p75 (75% benzyl ester, 25% sodium salt) and HYAFF 11 (100% benzyl ester). The polymer with the lowest degree of esterification, HYAFF 11 p25, was the most hydrophilic and released drug faster than those with higher degrees of esterification, HYAFF 11 and HYAFF 11 p75, which are generally less hydrophilic. Tear fluid prednisolone concentrations were measured in rabbits after administration of the test films. Areas under the tear fluid concentration vs time curves (AUC 0–8 h ) were calculated for all the dosage forms, from the time of dosing to 8 h post-dosing. The HYAFF 11 p25 films provided higher initial concentrations which rapidly declined below 30 μg/ml, 2 h post-dosing. Concentrations for the HYAFF 11 p75 film dropped below 30 μg/ml, 3 h post-dosing. The HYAFF 11 films provided the best results with sustained concentrations between 45 and 72 μg/ml for the 8 h study period. The results show that sustained delivery of prednisolone to the eye may be achieved with the use of hyaluronic acid esters.

Mucoadhesive properties of hyaluronic acid (HA) benzyl esters were evaluated. The vertical tensile force of detachment of polymer films from porcine gastric mucosal surface was measured with a microdisplacement transducer. The HA esters, namely, HYAFF 11 p25 (25% benzyl ester, 75% sodium salt), HYAFF 11 p50 (50% benzyl ester, 50% sodium salt), HYAFF 11 p75 (75% benzyl ester, 25% sodium salt) and HYAFF 11 (100% benzyl ester), were compared to glass (negative control) and to two positive controls, polycarbophil (PC) and hydroxypropylmethylcellulose (HPMC). Measurements were made for polymer films hydrated in a pH 1.2 medium, in Tyrode solution (pH 7.8) and for unhydrated films. When hydrated at pH 1.2, the more hydrophilic polymers (HPMC, HYAFF 11 p25, HYAFF 11 p50 and PC) showed significantly greater adhesion (2720–4192 dyn/cm 2 ) than the negative control (1980 dyn/cm 2 ). When hydrated at pH 7.8, only HPMC (3801 dyn/cm 2 ) and HYAFF 11 p25 (3198 dyn/cm 2 ) showed greater adhesion than the negative control. PC adhesion was significantly lower than at pH 1.2. The ionized state of PC, as well as mucus glycoprotein residues at this pH (7.8), may cause charge repulsion and reduced adhesion As expected, adhesion of HPMC which is nonionic, was unaffected by pH of the hydration medium. Adhesion of HYAFF 11 p25, and HYAFF 11 p50 was not significantly different at the higher pH. The adhesion of dry films was greater (4203–6388 dyn/cm 2 ) than that of hyrdrated films. Adhesion of the dry films may be a result of wetting of the films and dehydration of the mucous layer by the films. The study of initial contact time showed a time dependent increase in force of adhesion after an initial equilibration time. The results indicate potential applicability of the hydrophilic HA esters as mucoadhesive polymers.

Gellan is an anionic exocellular polysaccharide of microbial origin, having a characteristic property of cation-induced gellation. In the current study, gellan was evaluated for applications in ocular sustained release devices. A methylprednisolone (MP) ester of gellan (gellan-MP) was synthesized. Sustained release dosage forms evaluated were gellan-MP films, gellan films with physically incorporated MP and eye drops of MP suspended in a 0.6% w/w/ gellan dispersion in water. The control dosage form was a suspension of MP in normal saline. In vitro release ofMP from the test dosage forms was determined in a pH 7.4 phosphate buffer at 32 °C using a rotating bottle apparatus. MP concentrations in the tear fluid of New Zealand white rabbits were measured after ocular application of the dosage forms. In vitro, the gellan-MP films released covalently bound MP in an approximate zero-order pattern, whereas the release of physically incorporated MP from the gellan eye drops and films followed a square root of time relationship and anomalous kinetics, respectively. Compared with the MP suspension control, the gellan-MP films yielded an approximately 4-fold higher area under tear fluid concentration vs time curve, AUC0–8h, but exhibited a tendency to slip out of the eye due to a high degree of swelling. The in vivo release from films containing physically incorporated MP showed higher variability and provided mean AUC0–8h values approximately equal to the control values. The gellan eye drops containing MP yielded 2.6-fold higher AUC0–8h values than the control and also provided ease of administration. Gellan solutions might thus provide a versatile vehicle for ocular sustained release of drugs. The results also show that the gellan-MP ester can be used to increase the residence time of methylprednisolone in the tear fluid of rabbits.

Delivery of drugs to brain tumors is difficult due to the impermeability, and variable nature of the blood/tumor barrier. Of the various strategies designed to improve drug uptake-intracellularly and into the brain, cationic carriers seem to offer an advantage. In the current investigation cationic polysaccharide–methotrexate conjugates were examined in the rat. Conjugates were prepared from N,O-carboxymethyl chitosan (NOCC) and 3H-methotrexate (MTX) by two different synthetic schemes, resulting in NOCCMTX-1 and NOCCMTX-2. NOCCMTX-1 appeared to have a higher degree of cross-polymerization than NOCCMTX-2. Each conjugate and free MTX were administered intra-arterially in a retrograde manner in the external carotid artery at a MTX dose of 1 mg/kg as a constant rate infusion over 30 min. Animals were sacrificed at various times after administration, and blood and tissue samples collected, processed in a sample oxidizer, and then measured for radioactivity. Brain MTX concentrations were 18- and 12-fold greater at 15 min and 3 hr, respectively, following NOCCMTX-1 administration compared to free MTX treatment. However, NOCCMTX-1 resulted in animal death at about 12 hr after administration. NOCMTX-2 was found to be non-toxic, yet did not increase brain MTX concentrations compared to free drug administrations after correction for MTX in residual blood. Further investigations are planned to combine the positive drug targeting effect of NOCCMTX-1 with the safety of NOCCMTX-2.

Zidovudine (AZT), prepared as an alkaline solution, was administered iv and intraarterially (ia) by continuous infusion via an implantable pump in dogs. The AZT serum and cerebrospinal fluid (CSF) concentrations were measured over a 28-day treatment period by HPLC. Terminal brain AZT concentrations were also measured. Control (vehicle only) animals were also studied. All animals were evaluated for pathological changes associated with the AZT and vehicle infusions in catheterized vessels and other organs. In the iv AZT treatment group, serum AZT concentrations were relatively constant, with individual coefficients of variations (%CV) of 20% or less. Mean CSF:serum and brain:serum AZT concentration ratios were 0.149 and 0.212, respectively. In the ia AZT treatment group, serum AZT concentrations were more variable than in the iv group, with %CV ranging from 22 to 79%. The fluctuations in serum concentrations were attributed to temporary blockages of the outflow catheter. Mean CSF:serum and brain:serum AZT concentration ratios were 0.126 and 0.249, respectively. Pathological changes, similar in both control and treatment groups, included endothelial denudation and myointimal proliferation at the infusion sites. The conclusions of the study are (1) steady-state >1 μM AZT serum concentrations can be maintained chronically by use of an implantable pump containing a basic pH AZT solution; (2) ia delivery of AZT did not increase central nervous system uptake compared with iv administration; and (3) morbidity associated with the infused solutions does not seem to be a limitation for this mode of therapy.

Membranes of 75% and 100% benzyl hyaluronate esters (percentage of total carboxylate groups esterified) were prepared and their water vapour, oxygen and carbon dioxide transmission rates determined. The values of these properties were compared with the values obtained for several commercial wound dressings under the same conditions. The benzyl hyaluronate membranes showed water vapour transmission rates (2157–2327 g m −2 per day) comparable to those from commercial skin dressings (426–2047 g m −2 per day). In the dry state, the benzyl hyaluronate membranes showed lower oxygen and carbon dioxide transmission rates. Taking into account the biocompatibility of the hyaluronic acid esters, and the possibility that therapeutic agents could be incorporated into these membranes, the results indicate that the benzyl hyaluronate membranes have potential wound dressing applications.