Sequential combination therapy of ovarian cancer with degradable N-(2-hydroxypropyl)methacrylamide copolymer paclitaxel and gemcitabine conjugates

A Two-Step Pretargeted Nanotherapy for CD20 Crosslinking May Achieve Superior Anti-Lymphoma Efficacy to Rituximab

The use of rituximab, an anti-CD20 mAb, in combination with chemotherapy is the current standard for the treatment of B-cell lymphomas. However, because of a significant number of treatment failures, there is a demand for new, improved therapeutics. Here, we designed a nanomedicine that crosslinks CD20 and directly induces apoptosis of B-cells without the need for toxins or immune effector functions. The therapeutic system comprises a pretargeting component (anti-CD20 Fab' conjugated with an oligonucleotide1) and a crosslinking component (N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer grafted with multiple complementary oligonucleotide2). Consecutive treatment with the two components resulted in CD20 clustering on the cell surface and effectively killed malignant B-cells in vivo. To enhance therapeutic efficacy, a two-step pretargeting approach was employed. We showed that the time lag between the two doses can be optimized based on pharmacokinetics and biodistribution of the Fab'-oligonucleotide1 conjugate. In a mouse model of human non-Hodgkin lymphoma (NHL), increasing the time lag from 1 h to 5 h resulted in dramatically improved tumor growth inhibition and animal survival. When the 5 h interval was used, the nanotherapy was more efficacious than rituximab and led to complete eradication of lymphoma cells with no signs of metastasis or disease recurrence. We further evaluated the nanomedicine using patient mantle cell lymphoma cells; the treatment demonstrated more potent apoptosis-inducing activity than rituximab hyper-crosslinked with secondary antibodies. In summary, our approach may constitute a novel treatment for NHL and other B-cell malignancies with significant advantages over conventional chemo-immunotherapy.

Complete Regression of Xenograft Tumors upon Targeted Delivery of Paclitaxel via Π-Π Stacking Stabilized Polymeric Micelles

Treatment of cancer patients with taxane-based chemotherapeutics, such as paclitaxel (PTX), is complicated by their narrow therapeutic index. Polymeric micelles are attractive nanocarriers for tumor-targeted delivery of PTX, as they can be tailored to encapsulate large amounts of hydrophobic drugs and achiv prolonged circulation kinetics. As a result, PTX deposition in tumors is increased, while drug exposure to healthy tissues is reduced. However, many PTX-loaded micelle formulations suffer from low stability and fast drug release in the circulation, limiting their suitability for systemic drug targeting. To overcome these limitations, we have developed PTX-loaded micelles which are stable without chemical cross-linking and covalent drug attachment. These micelles are characterized by excellent loading capacity and strong drug retention, attributed to π-π stacking interaction between PTX and the aromatic groups of the polymer chains in the micellar core. The micelles are based on methoxy poly(ethylene glycol)-b-(N-(2-benzoyloxypropyl)methacrylamide) (mPEG-b-p(HPMAm-Bz)) block copolymers, which improved the pharmacokinetics and the biodistribution of PTX, and substantially increased PTX tumor accumulation (by more than 2000%; as compared to Taxol or control micellar formulations). Improved biodistribution and tumor accumulation were confirmed by hybrid μCT-FMT imaging using near-infrared labeled micelles and payload. The PTX-loaded micelles were well tolerated at different doses, while they induced complete tumor regression in two different xenograft models (i.e., A431 and MDA-MB-468). Our findings consequently indicate that π-π stacking-stabilized polymeric micelles are promising carriers to improve the delivery of highly hydrophobic drugs to tumors and to increase their therapeutic index.

Thymoquinone Pretreatment Overcomes the Insensitivity and Potentiates the Antitumor Effect of Gemcitabine Through Abrogation of Notch1, PI3K/Akt/mTOR Regulated Signaling Pathways in Pancreatic Cancer

BACKGROUND

The gemcitabine-insensitivity remains the main challenge for pancreatic cancer treatment. Thymoquinone, the predominant bioactive ingredient of Nigella sativa, has been shown to possess promising anti-cancer and chemo-sensitizing effects on pancreatic cancer, however, its meticulous mechanism is still indistinct.

AIM

The objective of the present study was to investigate the potency of thymoquinone in combination with gemcitabine in inducing apoptosis and preventing the development of gemcitabine-insensitivity in pancreatic cancer cells.

METHODS

The anti-tumor effects of thymoquinone and gemcitabine were analyzed via evaluation of alterations of cell viability, tumor weight, apoptosis-related proteins, caspase-3, -9 activities and NF-κB DNA binding activity in pancreatic cancer cells in vitro and PANC-1 cells orthotopic xenograft in vivo.

RESULTS

Thymoquinone pretreatment following gemcitabine treatment synergistically caused an increase in pancreatic cancer cells apoptosis and tumor growth inhibition both in vitro and in vivo. The novel combinational regimen also contributes to alterations of multiple molecular signaling targets, such as the suppression of Notch1, NICD accompanying with up-regulation of PTEN, the inactivation of Akt/mTOR/S6 signaling pathways, and the suppression of phosphorylation and nuclear translocation of p65 induced by TNF-α. Thymoquinone pretreatment and gemcitabine also induced down-regulation of anti-apoptotic Bcl-2, Bcl-xL, XIAP and up-regulation and activation of pro-apoptotic molecules including Caspase-3, Caspase-9, Bax and increased release of cytochrome c.

CONCLUSIONS

This novel modality of thymoquinone pretreatment can enhance the anti-cancer activity of gemcitabine and may be a promising option in the treatment of pancreatic cancer.

The rational design of a gemcitabine prodrug with AIE-based intracellular light-up characteristics for selective suppression of pancreatic cancer cells

An enzyme and reduction-activatable gemcitabine prodrug with AIE properties was designed for targeted and image-guided pancreatic cancer therapy.

HPMA Copolymer CXCR4 Antagonist Conjugates Substantially Inhibited the Migration of Prostate Cancer Cells

A N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer–CXCR4 antagonist (BKT140) conjugate (P-BKT140) was developed and its biological activities were tested. Both free BKT140 and monomer MA-GGPLGLAG-BKT140 (MA is methacryloyl) were prepared by solid phase synthesis. P-BKT140 was prepared by reversible addition–fragmentation chain transfer (RAFT) copolymerization of monomers HPMA and MA-GGPLGLAG-BKT140. The in vitro results show that the free BKT140 and P-BKT140 have similar cytotoxicity against human prostate carcinoma PC-3 cells, indicating that conjugation of BKT140 to HPMA did not significantly impact the cytotoxicity of BKT140. Both BKT140 and P-BKT140 inhibited the CXCL12-induced migration of PC-3 prostate cancer cells, but the P-BKT140 conjugate possessed a substantially higher inhibition activity than free BKT140.

Macromolecular therapeutics

This review covers water-soluble polymer-drug conjugates and macromolecules that possess biological activity without attached low molecular weight drugs. The main design principles of traditional and backbone degradable polymer-drug conjugates as well as the development of a new paradigm in nanomedicines - (low molecular weight) drug-free macromolecular therapeutics are discussed. To address the biological features of cancer, macromolecular therapeutics directed to stem/progenitor cells and the tumor microenvironment are deliberated. Finally, the future perspectives of the field are briefly debated.