PB101, a VEGF- and PlGF-targeting decoy protein, enhances antitumor immunity and suppresses tumor progression and metastasis.

Antiangiogenic therapy is a recognized method for countering the immunosuppressive tumor microenvironment (TME) and improving anti-tumor immunity. PB101 is a glycosylated decoy receptor that binds to VEGF-A and PlGF with high affinity, based on the VEGFR1 backbone. Here, we elucidated PB101-induced remodeling of tumor angiogenesis and immunity, which enhances anti-PD-L1 immune checkpoint blockade. PB101 inhibited tumor growth by suppressing angiogenesis and enhancing CD8+ T cell infiltration into the tumors. PB101 induced robust reprogramming of antitumor immunity and activates intratumoral CD8+ T cells. Anti-tumor efficacy of PB101 is mostly dependent on CD8+ T cells and IFN-γ. PB101 reprograms tumor immunity in a manner distinct from that of the conventional VEGF decoy receptor, VEGF-trap. With its potent immune-modulating capability, PB101 synergizes with an anti-PD-L1, triggering strengthened antitumor immunity. Combining PB101 and anti-PD-L1 could establish durable protective immunity against tumor recurrence and metastasis. The findings of this study offer scientific rationales for further clinical development of PB101, particularly when used in combination with immune checkpoint inhibitors, as a potential treatment for advanced cancers.

Discovery of a novel natural killer cell line with distinct immunostimulatory and proliferative potential as an alternative platform for cancer immunotherapy.

BACKGROUND: Human natural killer (NK) cell lines serve as an attractive source for adoptive immunotherapy, but NK-92 remains the only cell line being assessed in the clinic. Here, we established a novel NK cell line, NK101, from a patient with extra-nodal natural killer/T-cell lymphoma and examined its phenotypic, genomic and functional characteristics. METHODS: Single cell suspensions from lymphoma tissue were expanded with anti-NKp46/anti-CD2-coated beads in the presence of IL-2. A continuously growing CD56+ cell clone was selected and designated as NK101. Flow cytometry and RNA sequencing were used to characterize phenotypic and genomic features of NK101. In vitro cytotoxicity and IFN-γ/TNF-α secretion were measured by flow cytometry-based cytotoxicity assay and enzyme-linked immunosorbent assay, respectively, after direct co-culture with tumor cells. Immunomodulatory potential of NK101 was assessed in an indirect co-culture system using conditioned medium. Finally, in vivo antitumor efficacy was evaluated in an immunocompetent, syngeneic 4T1 mammary tumor model. RESULTS: NK101 displayed features of CD56dimCD62L+ intermediate stage NK subset with the potential to simultaneously act as a cytokine producer and a cytotoxic effector. Comparative analysis of NK101 and NK-92 revealed that NK101 expressed lower levels of perforin and granzyme B that correlated with weaker cytotoxicity, but produced higher levels of pro-inflammatory cytokines including IFN-γ and TNF-α. Contrarily, NK-92 produced greater amounts of anti-inflammatory cytokines, IL-1 receptor antagonist and IL-10. Genome-wide analysis revealed that genes associated with positive regulation of leukocyte proliferation were overexpressed in NK101, while those with opposite function were highly enriched in NK-92. The consequence of such expressional and functional discrepancies was well-represented in (i) indirect co-culture system where conditioned medium derived from NK101 induced greater proliferation of human peripheral blood mononuclear cells and (ii) immunocompetent 4T1 tumor model where peritumoral injections of NK101 displayed stronger anti-tumor activities by inducing higher tumor-specific immune responses. In a manufacturing context, NK101 not only required shorter recovery time after thawing, but also exhibited faster growth profile than NK-92, yielding more than 200-fold higher cell numbers after 20-day culture. CONCLUSION: NK101 is a unique NK cell line bearing strong immunostimulatory potential and substantial scalability, providing an attractive source for adoptive cancer immunotherapy.

Clearance of persistent HPV infection and cervical lesion by therapeutic DNA vaccine in CIN3 patients.

Here, we demonstrate that electroporation-enhanced immunization with a rationally designed HPV DNA vaccine (GX-188E), preferentially targeting HPV antigens to dendritic cells, elicits a significant E6/E7-specific IFN-γ-producing T-cell response in all nine cervical intraepithelial neoplasia 3 (CIN3) patients. Importantly, eight out of nine patients exhibit an enhanced polyfunctional HPV-specific CD8 T-cell response as shown by an increase in cytolytic activity, proliferative capacity and secretion of effector molecules. Notably, seven out of nine patients display complete regression of their lesions and viral clearance within 36 weeks of follow up. GX-188E administration does not elicit serious vaccine-associated adverse events at all administered doses. These findings indicate that the magnitude of systemic polyfunctional CD8 T-cell response is the main contributing factor for histological, cytological and virological responses, providing valuable insights into the design of therapeutic vaccines for effectively treating persistent infections and cancers in humans.

KIAA1114, a full-length protein encoded by the trophinin gene, is a novel surface marker for isolating tumor-initiating cells of multiple hepatocellular carcinoma subtypes.

Identification of novel biomarkers for tumor-initiating cells (TICs) is of critical importance for developing diagnostic and therapeutic strategies against cancers. Here we identified the role of KIAA1114, a full-length translational product of the trophinin gene, as a distinctive marker for TICs in human liver cancer by developing a DNA vaccine-induced monoclonal antibody targeting the putative extracellular domain of KIAA1114. Compared with other established markers of liver TICs, KIAA1114 was unique in that its expression was detected in both alpha fetoprotein (AFP)-positive and AFP-negative hepatocellular carcinoma (HCC) cell lines with the expression levels of KIAA1114 being positively correlated to their tumorigenic potentials. Notably, KIAA1114 expression was strongly detected in primary hepatic tumor, but neither in the adjacent non-tumorous tissue from the same patient nor normal liver tissue. KIAA1114high cells isolated from HCC cell lines displayed TIC-like features with superior functional and phenotypic traits compared to their KIAA1114low counterparts, including tumorigenic abilities in xenotransplantation model, in vitro colony- and spheroid-forming capabilities, expression of stemness-associated genes, and migratory capacity. Our findings not only address the value of a novel antigen, KIAA1114, as a potential diagnostic factor of human liver cancer, but also as an independent biomarker for identifying TIC populations that could be broadly applied to the heterogeneous HCC subtypes.

Complete regression of metastatic renal cell carcinoma by multiple injections of engineered mesenchymal stem cells expressing dodecameric TRAIL and HSV-TK.

PURPOSE: Durable complete remission of metastatic renal cell carcinoma (RCC) has rarely been achieved with current treatment modalities. To solve this problem, alternative therapeutic options with high efficacy and minimal side effects are strongly needed. EXPERIMENTAL DESIGN: Mesenchymal stem cells (MSC) were engineered to coexpress dodecameric TRAIL and herpes simplex virus thymidine kinase (MSC/dTRAIL-TK). The antitumor effects of MSCs expressing dTRAIL (MSC/dTRAIL) or HSV-TK alone (MSC/TK) and MSC/dTRAIL-TK were compared with murine RCC cells using in vitro coculture system and in vivo experimental lung metastasis model. The effects of different doses and schedules of engineered MSCs on mice survival were also evaluated. RESULTS: MSC/dTRAIL-TK exerted stronger apoptotic response in Renca cells than did MSC/TK or MSC/dTRAIL after ganciclovir (GCV) treatment. In vivo imaging results suggest that MSCs reside longer in the lungs of metastatic tumor-bearing mice, compared with that of control mice, regardless of genetic engineering. In addition, MSC/dTRAIL-TK treatment followed by ganciclovir administrations significantly decreased the number of tumor nodules in the lung, to a greater degree than MSC/dTRAIL or MSC/TK, and led to a prolonged survival. More importantly, the antimetastatic effect of MSC/dTRAIL-TK was markedly enhanced by repeated injections but not by increased dose, and resulted in 100% survival of tumor-bearing mice after three injections. CONCLUSION: Sequential combination gene therapy using MSC/dTRAIL-TK achieved long-term remission of metastatic RCC without noticeable toxicity. Our findings provide an innovative therapeutic approach to completely eradicate metastatic tumors by simple, repeated administrations of MSC/dTRAIL-TK.