Improved Cancer Immunochemotherapy via Optimal Co-delivery of Chemotherapeutic and Immunomodulatory Agents.

It is highly demanded and still a big challenge to develop an effective formulation for immunochemotherapy against advanced tumors. We have previously reported a PEG-NLG-based immunostimulatory nanocarrier (PEG2k-Fmoc-NLG919) for co-delivery of an IDO1 inhibitor (NLG919) and a chemotherapeutic agent (paclitaxel, PTX). Although antitumor immune responses were enhanced with a PTX-loaded nanocarrier, the accumulation of myeloid-derived suppressor cells (MDSCs) was also significantly increased, which may limit the overall efficacy of therapy. In the present work, we developed an improved dual-functional nanocarrier (PEG5k-Fmoc-NLG2) to co-load PTX and sunitinib (SUN, a multitarget receptor tyrosine kinase inhibitor) for improved cancer immunochemotherapy. We found that the recruited MDSCs negatively impacted the overall antitumor activity of the PTX-loaded PEG-NLG nanocarrier. Mechanistic study suggests that this is likely attributed to the PTX-mediated induction of a number of chemokines that are involved in the recruitment of MDSCs. We have further shown that the induction of these chemokines was drastically blocked by SUN. Co-delivery of PTX and SUN via the PEG5k-Fmoc-NLG9192 nanocarrier led to a further improvement in the therapeutic efficacy with a concomitant reduction in MDSCs.

Programmable co-delivery of the immune checkpoint inhibitor NLG919 and chemotherapeutic doxorubicin via a redox-responsive immunostimulatory polymeric prodrug carrier.

To achieve synergistic therapeutic efficacy and prevent cancer relapse, chemotherapy and immunotherapy have been combined as a new modality for tumor treatment. In this work, we designed a redox-responsive immunostimulatory polymeric prodrug carrier, PSSN10, for programmable co-delivery of an immune checkpoint inhibitor NLG919 (NLG) and a chemotherapeutic doxorubicin (DOX). NLG-containing PSSN10 prodrug polymers were self-assembled into nano-sized micelles that served as a carrier to load DOX (DOX/PSSN10 micelles). DOX/PSSN10 micelles displayed spherical morphology with a size of ∼170 nm. DOX was effectively loaded into PSSN10 micelles with a loading efficiency of 84.0%. In vitro DOX release studies showed that rapid drug release could be achieved in the highly redox environment after intracellular uptake by tumor cells. In 4T1.2 tumor-bearing mice, DOX/PSSN10 micelles exhibited greater accumulation of DOX and NLG in the tumor tissues compared with other organs. The PSSN10 carrier dose-dependently enhanced T-cell immune responses in the lymphocyte-Panc02 co-culture experiments, and significantly inhibited tumor growth in vivo. DOX/PSSN10 micelles showed potent cytotoxicity in vitro against 4T1.2 mouse breast cancer cells and PC-3 human prostate cancer cells comparable to that of DOX. In 4T1.2 tumor-bearing mice, DOX/PSSN10 mixed micelles (5 mg DOX/kg, iv) was more effective than DOXIL (a clinical formulation of liposomal DOX) or free DOX in inhibiting the tumor growth and prolonging the survival of the treated mice. In addition, a more immunoactive tumor microenvironment was observed in the mice treated with PSSN10 or DOX/PSSN10 micelles compared with the other treatment groups. In conclusion, systemic delivery of DOX via PSSN10 nanocarrier results in synergistic anti-tumor activity.

Triple drugs co-delivered by a small gemcitabine-based carrier for pancreatic cancer immunochemotherapy.

Poor tumor penetration and highly immunosuppressive tumor microenvironment are two major factors that limit the therapeutic efficacy for the treatment of pancreatic ductal adenocarcinoma (PDA). In this work, a redox-responsive gemcitabine (GEM)-conjugated polymer, PGEM, was employed as a tumor penetrating nanocarrier to co-load an immunomodulating agent (NLG919, an inhibitor of indoleamine 2,3-dioxygenase 1 (IDO1) and a chemotherapeutic drug (paclitaxel (PTX)) for immunochemo combination therapy. The NLG919/PTX co-loaded micelles showed very small size of ~15 nm. In vivo tumor imaging study indicated that PGEM was much more effective than the relatively large-sized POEG-co-PVD nanoparticles (~160 nm) in deep tumor penetration and could reach the core of the pancreatic tumor. PTX formulated in the PGEM carrier showed improved tumor inhibition effect compared with PGEM alone. Incorporation of NLG919 in the formulation led to a more immunoactive tumor microenvironment with significantly decreased percentage of Treg cells, and increased percentages of CD4+ IFNγ+ T and CD8+ IFNγ+ T cells. PGEM micelles co-loaded with PTX and NLG919 showed the best anti-tumor activity in pancreatic (PANC02) as well as two other tumor models compared to PGEM micelles loaded with PTX or NLG919 alone, suggesting that codelivery of NLG919 and PTX via PGEM may represent an effective strategy for immunochemotherapy of PDA as well as other types of cancers. STATEMENT OF SIGNIFICANCE: In order to effectively accumulate and penetrate the PDA that is poorly vascularized and enriched with dense fibrotic stroma, the size of nanomedicine has to be well controlled. Here, we reported an immunochemotherapy regimen based on co-delivery of GEM, PTX and IDO1 inhibitor NLG919 through an ultra-small sized GEM-based nanocarrier (PGEM). We demonstrated that the PGEM carrier was effective in accumulating and penetrating into PDA tumors. Besides, PGEM co-loaded with PTX and NLG9 induced an improved anti-tumor immune response and was highly efficacious in inhibiting tumor growth as well as in prolonging the survival rate in PANC02 xenograft model. Our work represents a potential strategy for enhancing PDA tumor penetration and immunochemotherapy.

An immunostimulatory dual-functional nanocarrier that improves cancer immunochemotherapy.

Immunochemotherapy combines a chemotherapeutic agent with an immune-modulating agent and represents an attractive approach to improve cancer therapy. However, the success of immunochemotherapy is hampered by the lack of a strategy to effectively co-deliver the two therapeutics to the tumours. Here we report the development of a dual-functional, immunostimulatory nanomicellar carrier that is based on a prodrug conjugate of PEG with NLG919, an indoleamine 2,3-dioxygenase (IDO) inhibitor currently used for reversing tumour immune suppression. An Fmoc group, an effective drug-interactive motif, is also introduced into the carrier to improve the drug loading capacity and formulation stability. We show that PEG2k-Fmoc-NLG alone is effective in enhancing T-cell immune responses and exhibits significant antitumour activity in vivo. More importantly, systemic delivery of paclitaxel (PTX) using the PEG2k-Fmoc-NLG nanocarrier leads to a significantly improved antitumour response in both breast cancer and melanoma mouse models.