Nanoscale liposomal formulation of a SYK P-site inhibitor against B-precursor leukemia.

We report preclinical proof of principle for effective treatment of B-precursor acute lymphoblastic leukemia (ALL) by targeting the spleen tyrosine kinase (SYK)-dependent antiapoptotic blast cell survival machinery with a unique nanoscale pharmaceutical composition. This nanoscale liposomal formulation (NLF) contains the pentapeptide mimic 1,4-Bis (9-O dihydroquinidinyl) phthalazine/hydroquinidine 1,4-phathalazinediyl diether (C61) as the first and only selective inhibitor of the substrate binding P-site of SYK. The C61 NLF exhibited a very favorable pharmacokinetic and safety profile in mice, induced apoptosis in primary B-precursor ALL blast cells taken directly from patients as well as in vivo clonogenic ALL xenograft cells, destroyed the in vivo clonogenic fraction of ALL blast cells, and, at nontoxic dose levels, exhibited potent in vivo antileukemic activity against patient-derived ALL cells in xenograft models of aggressive B-precursor ALL. Our findings establish SYK as an attractive molecular target for therapy of B-precursor ALL. Further development of the C61 NLF may provide the foundation for therapeutic innovation against therapy-refractory B-precursor ALL.

CD19-antigen specific nanoscale liposomal formulation of a SYK P-site inhibitor causes apoptotic destruction of human B-precursor leukemia cells.

We report the anti-leukemic potency of a unique biotargeted nanoscale liposomal nanoparticle (LNP) formulation of the spleen tyrosine kinase (SYK) P-site inhibitor C61. C61-loaded LNP were decorated with a murine CD19-specific monoclonal antibody directed against radiation-resistant CD19-receptor positive aggressive B-precursor acute lymphoblastic leukemia (ALL) cells. The biotargeted C61-LNP were more potent than untargeted C61-LNP and consistently caused apoptosis in B-precursor ALL cells. The CD19-directed C61-LNP also destroyed B-precursor ALL xenograft cells and their leukemia-initiating in vivo clonogenic fraction. This unique nanostructural therapeutic modality targeting the SYK-dependent anti-apoptotic blast cell survival machinery shows promise for overcoming the clinical radiochemotherapy resistance of B-precursor ALL cells.

A novel vaginal microbicide containing the rationally designed anti-HIV compound HI-443 (N'-[2-(2-thiophene)ethyl]-N'-[2-(5-bromopyridyl)] thiourea]).

INTRODUCTION: A focal point in contemporary research aimed at preventing the heterosexual spread of AIDS has been the development of intravaginal anti-HIV microbicides to curb the mucosal human immunodeficiency virus type 1 (HIV-1) transmission. AREAS COVERED: This article reviews the preclinical activity and safety profile of the thiophene thiourea PETT derivative, HI-443 (N'-[2-(2-thiophene)ethyl]-N'-[2-(5-bromopyridyl)] thiourea]). HI-443 is a rationally designed non-nucleoside reverse transcriptase inhibitor (NNRTI) with unprecedented activity against primary clinical HIV-1 isolates with NRTI or NNRTI resistance, multidrug resistance as well as non-B envelope subtypes of HIV-1. HI-443 exhibited a favorable toxicity and pharmacokinetics profile following oral, intraperitoneal or intravenous administration in rodents and a favorable safety profile after repeated intravaginal dosing via a gel formulation in rabbits and pigs. HI-443 did not induce the secretion of pro-inflammatory cytokines and chemokines by three-dimensional reconstituted human vaginal epithelia integrating Langerhans cells ex vivo or in the in vivo porcine model at therapeutic dose levels. Intravaginally administered HI-443 prevented vaginal transmission of a drug-resistant clinical HIV-1 isolate in the surrogate Hu-PBL-SCID mouse model of AIDS. EXPERT OPINION: The discovery of HI-443 as a non-spermicidal broad-spectrum antiretroviral agent represents a significant step forward in the development of a prophylactic microbicide without contraceptive activity for curbing heterosexual HIV transmission.

Targeting Mantle Cell Lymphoma with Anti-SYK Nanoparticles.

The pentapeptide mimic 1,4-bis(9-O-dihydroquinidinyl)phthalazine / hydroquinidine 1,4-phathalazinediyl diether ("compound 61") (C-61) is the first reported inhibitor targeting the P-site of SYK. Here we report a nanotechnology platform to target C-61 to mantle cell lymphoma (MCL) cells. Liposomal nanoparticles (NP) loaded with C-61 were prepared using the standard thin film evaporation method. The entrapment of C-61 was obtained using the pH gradient procedure with lactobionic acid (LBA) being used as a low pH buffer inside the NP. Formulation F6A was selected as a lead candidate for further biological testing. The average diameter, zeta potential and C-61 content of the F6A NP was 40 nm, 0.1 mV, and 12.6 mg/ml, respectively. F6A induces apoptosis in SYK+ but not SYK- leukemia/lymphoma cells. We also evaluated the cytotoxic activity of F6A in the context of an in vitro artificial bone marrow assay platform based on a 3D scaffold with inverted colloidal crystal geometry mimicking the structural topology of actual bone marrow matrix. The ability of C-61 to induce apoptosis in ALL-1 cells was not adversely affected by the scaffolds. F6A, but not the drug-free NP formulation F6B, caused apoptosis of MCL cell lines MAVER-1 and MINO within 24h. Further development of rationally designed SYK inhibitors and their nanoscale formulations may provide the foundation for therapeutic innovation against a broad spectrum of lymphoid malignancies, including MCL.

Therapeutic nanoparticle constructs of a JAK3 tyrosine kinase inhibitor against human B-lineage ALL cells.

WHI-P131 (CAS 202475-60-3) is a dual-function inhibitor of JAK3 tyrosine kinase that demonstrated potent in vivo anti-inflammatory and anti-leukemic activity in several preclinical animal models. This is the first report of the development of nanoparticle (NP) constructs ofWHI-P131. Fourty-eight distinct NP formulations were prepared and WHI-P131 encapsulation efficiencies > 95% and intraliposomal WHI-P131 concentrations >10 mg/mL were achieved in lead NP formulations. The anti-cancer activity of WHI-P131-NP, a PEGylated lead formulation was tested in vitro and in vivo. Notably, WHI-P131-NP was capable of causing apoptotic death in primary leukemia cells from chemotherapy-resistant acute lymphoblastic leukemia (ALL) as well as chronic lymphocytic leukemia (CLL) patients. WHI-P131-NP was also active in the RS4;11 SCID mouse xenograft model of chemotherapy-resistant B-lineage ALL. The life table analysis showed that WHI-P131-NP was more effective than WHI-P131 (P = 0.01), vincristine (P < 0.0001), or vehicle (P < 0.0001). These experimental results demonstrate that the nanotechnology-enabled delivery of WHI-P131 shows therapeutic potential against leukemias with constitutive activation of the JAK3-STAT3/STAT5 molecular target.