Murine Renal Cell Carcinoma Research Articles

A modified IL-18 drug in combination with CTLA-4 blockade enhances anti-tumor efficacy in preclinical models of renal cell carcinoma

Abstract Background Cytokine-based drugs are currently being explored as alternative cancer immunotherapies. While the cytokine interleukin-18 (IL-18) has immunostimulatory effects, it is negatively regulated by a secreted high-affinity binding protein, IL-18BP, that functions as an immune checkpoint that limits IL-18’s efficacy as a cancer therapeutic. A modified version of IL-18, termed “decoy-resistant” or DR-18, that can avoid trapping by IL-18BP while still maintaining its immune signaling potential, has recently been developed. DR-18 has shown promising preclinical activity in melanoma and colorectal murine models, including potential synergy with anti-PD-1 therapy, and is currently in Phase I trials. In this study, we aim to test the efficacy and determine the cellular mechanism of action of DR-18 in combination with immune checkpoint inhibitors (ICIs) in immunocompetent preclinical models of renal cell carcinoma (RCC), with the goal of establishing the basis for testing these combinations in early phase clinical trials. Methods We engrafted tumors subcutaneously using two different syngeneic, immunocompetent murine RCC models: Renca and RAG. Mice were treated with single-agent DR-18 and combinations of DR-18 with single- and dual-agent anti-PD-1 and anti-CTLA-4. Tumor growth and survival were monitored. In the Renca model, plasma was collected at early time-points and cytokine/chemokine levels were profiled using a 31-plex discovery assay. Single-cell RNA and TCR sequencing was also performed on Renca tumors. Additionally, immune cell depletion studies were conducted in the Renca model with antibodies targeting CD8, CD4, NK cells, and interferon-gamma. Results In the Renca model, DR-18 monotherapy modestly inhibited tumor growth and prolonged survival. The effects were comparable to single- and dual-agent ICIs. Adding PD-1 blockade to DR-18 did not enhance efficacy whereas the addition of anti-CTLA-4 to DR-18 significantly increased anti-tumor effects. Triple-therapy (DR-18 plus anti-PD-1 plus anti-CTLA-4) did not further inhibit tumor growth or prolong survival compared to the doublet (DR-18 plus anti-CTLA-4). The RAG model was more sensitive to ICIs but produced similar results, again showing modest anti-tumor activity of single-agent DR-18 and enhanced benefit of combining with anti-CTLA-4 but not anti-PD-1. Cytokine/chemokine profiling revealed significantly elevated levels of IP-10 (CXCL10) and MIG (CXCL9) after one cycle of DR-18 plus anti-CTLA-4 compared to control and single-agent treatments, suggesting that these chemokines may be key early mediators of the anti-tumor immune response. Single-cell transcriptomic analysis demonstrated changes in intra-tumoral T cell, macrophage, and granulocyte populations with DR-18 plus anti-CTLA-4 relative to other regimens, including enrichment of CD8+ precursor and terminally exhausted T cells and a neutrophil population associated with interferon signaling. Additionally, single-cell TCR analysis showed a reduction in intra-tumoral clonotype diversity with DR-18 plus anti-CTLA-4 compared to other treatments. Immune cell depletion studies identified CD8+ T cells, NK cells, and interferon-gamma, but not CD4+ T cells, as equally required for efficacy of DR-18 plus anti-CTLA-4. Conclusions In this study, we identify DR-18, an IL-18-based drug engineered with resistance to a secreted decoy-receptor protein, in combination with anti-CTLA-4 as having enhanced anti-tumor activity in preclinical models of RCC. This regimen was associated with a more pro-inflammatory immune microenvironment. Further investigation is ongoing to elucidate the cellular mechanism of action of this regimen more fully and lay the groundwork for clinical testing of DR-18-based combination therapy in RCC. In the future, testing novel partner agents outside of anti-PD-1/CTLA-4 and using RCC models of ICI-resistance could be particularly informative and clinically relevant.

Abstract B026: Combined inhibition of mammalian target of rapamycin (mTOR) and survivin augments radiation therapy in renal cell carcinoma

Abstract Purpose: Although renal cell carcinoma (RCC) is relatively more resistant to radiation therapy (RT) compared to other cancer indications, recent advances in single-fraction and multi-fraction stereotactic ablative radiotherapy (SABR) made it possible to achieve better outcome and reduce treatment related toxicities. In addition, with studies demonstrating that certain therapeutic agents including chemotherapies can act as radiosensitizers, the idea of combining radiotherapy with those agents are being actively pursued. Among them, mammalian target of rapamycin (mTOR) inhibitor everolimus (E) and survivin inhibitor YM155 (Y) are of special interest since they target multiple RT-resistance mechanisms simultaneously. Additionally, YM155 has been shown to help in overcoming resistance to mTOR inhibitors in various cancer including RCC. Hence, the present study aims to evaluate the efficacy of a tumor-targeted liposomal formulation combining everolimus and YM155 (EY-L) in sensitizing RCC tumors towards radiation. Experimental Design: Previously we developed a tumor-targeted liposomal formulation and used it successfully to deliver multiple drugs for the treatment of RCC in both immune-deficient and immune-competent mouse models. Here we developed a similar formulation combining everolimus and YM155 (EY-L) and assessed its efficacy in RCC cell lines in vitro and in RCC tumors in vivo. We further evaluated the efficacy of EY-L in sensitizing RCC cell lines and tumors towards radiation in vitro using clonogenic assay and in vivo in RCC xenografts in immunodeficient mice and murine RCC models in immunocompetent mice. Results: EY-L (2 mg/kg E, 1.4 mg/kg Y, twice a week intravenous administration) was better than E-L or Y-L, the corresponding single drug loaded formulations in containing the primary tumor growth and improving survival in an immunocompetent syngeneic mouse model of RCC. Furthermore, EY-L leads to significantly higher sensitization of RCC cells towards radiation in vitro than E-L or Y-L. Finally, EY-L was able to sensitize RCC tumors towards radiation therapy in both RCC xenograft and murine RCC model. Conclusion: Taken together, our study demonstrated the efficacy of a strategic combination therapy in sensitizing RCC to radiation therapy using in vitro clonogenic assay and in vivo radiosensitization studies in multiple RCC tumor models. Citation Format: Krishnendu Pal, Vijay S. Madamsetty, Hari K. Rachamala, Shamit K. Dutta, Enfeng Wang, Debabrata Mukhopadhyay. Combined inhibition of mammalian target of rapamycin (mTOR) and survivin augments radiation therapy in renal cell carcinoma [abstract]. In: Proceedings of the AACR Special Conference: Advances in Kidney Cancer Research; 2023 Jun 24-27; Austin, Texas. Philadelphia (PA): AACR; Cancer Res 2023;83(16 Suppl):Abstract nr B026.

Abstract 6792: Targeting immunosuppressive adenosine to enhance vaccinia virus renal cancer oncolysis in vivo

Abstract Background: The oncolytic vaccinia virus (VV) is a promising biotherapy undergoing clinical development in human cancer, including renal cell carcinoma (RCC). While VV induces potent tumor oncolysis and immunomodulation, clinical experience has shown that OV therapy alone leads to limited benefit. Moreover, OVs and checkpoint inhibitor combinations, do not significantly improve clinical responses, underscoring the need to identify new tumor microenvironment targets to overcome OV resistance in vivo. The adenosine pathway is a biologically and clinically relevant target in RCC and is associated with adaptive resistance to immunotherapy. The objectives of this study are to characterize the role of the adenosine axis in tumor escape mechanisms to vaccinia virus in RCC, and to determine the efficacy of novel OV-immunotherapy combinations targeting adenosine. Methods: The in vitro oncolytic effects of JX-594 and mJX-594 (oncolytic VVs expressing human or murine GMCSF, respectively) in human (786-0, ACHN, CAKi-1, UOK262) and murine (RENCA) renal cancer cell lines were assessed. Proteomic analysis of 786-0 lysates treated with JX-594 was performed for mechanistic studies. The effects of JX-594 and mJX 594 on CD73 and CD39 expression were determined in human and murine RCC. In vivo antitumor effects of mJX-594 alone, and in combination with A2AR, A2BR and Dual Adenosine receptor inhibition was determined in the RENCA model in immunocompetent mice. Results: Potent in vitro oncolysis and efficient viral replication were observed in human and murine RCC cells after infection with vaccinia virus. VV oncolysis was associated with significant modulation of proliferation, survival, and ER stress pathways, as determined by functional proteomics. JX-594 and mJX-594 treatment induced increased expression of CD39 and CD73 in RCC cell lines and in renal tumors in vivo. While no significant enhancement of vaccinia oncolysis was observed with combinations with A2AR and A2BR inhibitors in vitro, a significant improvement on in vivo tumor control and survival were observed when mJX594 given intravenously was combined with A2AR and A2BR inhibitors (triplet), at a higher degree than single agents or doublets (mJX-594 in combination with single A2AR or A2BR inhibitors). Characterization of treatment mediated changes in immune signatures (nanostring) is underway and will be presented at the meeting. Conclusion: Vaccinia virus potently induces in vitro oncolysis in RCC cell lines, while also increasing expression of adenosine rate limiting enzymes in vitro and in vivo, which could explain tumor escape to oncolytic VV. MJX-594 combination with A2AR and A2BR inhibition safely and significantly improves renal cancer oncolysis and tumor control in vivo. Our studies uncover a novel, translationally relevant strategy to improve OV efficacy in vivo, in RCC and other cancers. Citation Format: Valery A. Chavez, Floritza Bustamante, Carolina Merchan-Mendes, Shannon Saigh, Patricia Guevara, Eric Wieder, Jaime Merchan. Targeting immunosuppressive adenosine to enhance vaccinia virus renal cancer oncolysis in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6792.

Abstract 5071: Olverembatinib (HQP1351) enhances antitumor effects of immunotherapy in renal cell carcinoma (RCC)

Abstract In solid tumors, resistance to checkpoint inhibitors (CPIs) is frequently observed, partially due to upregulation of vascular endothelial growth factor A (VEGFA) and programmed death-ligand 1 (PD-L1). This culminates in an immunosuppressive tumor microenvironment and immune escape. Inhibitors against VEGF and the VEGF receptor (VEGFR) foster tumor vessel normalization and immunostimulatory reprogramming, in turn promoting treatment effects of immunotherapies. In recent years, TKIs, including axitinib, lenvatinib, and cabozantinib, plus immunotherapy have been approved to treat advanced RCC. Currently under clinical development for relapsed or refractory chronic myeloid leukemia and gastrointestinal tumor, olverembatinib (HQP1351) is a new-generation multikinase inhibitor with targets including VEGFR, fibroblast growth factor receptor (FGFR), SRC, BCR-ABL1, c-KIT, and platelet-derived growth factor receptor. The aim of this study was to assess whether olverembatinib combined with immunotherapy can promote inhibitory effects on RCC. In cell-free kinase assays, olverembatinib inhibited VEGFR1, -2, and -3 with IC50 values of 4.2, 6.1, and 4.1 nM, respectively. Compared to lenvatinib, olverembatinib had more potent antiproliferative effects on human umbilical vein endothelial cells. Olverembatinib also had antiproliferative activity in murine RCC lines RANCA and RAG, with IC50 values of 141 and 53 nM, respectively. When olverembatinib was coadministered with an anti-PD-1 antibody in a RANCA-derived syngeneic model, both agents exerted synergistic effects, with tumor growth inhibition rates reaching 60.6%. Mechanistically, olverembatinib influenced cancer cell proliferation directly by inhibiting phosphorylation of FGFR and downstream proteins. Increased cleavage of caspase-3 and poly (ADP-ribose) polymerase 1 were observed, suggesting induction of apoptosis. Olverembatinib also influenced proliferation of vascular endothelial cells by inhibiting phosphorylation of VEGFR, SRC, and downstream proteins Akt and extracellular signal-regulated kinases. Olverembatinib also reduced expression of PD-L1 in RCC cells. In tumor-infiltrating lymphocyte assays, olverembatinib increased numbers of cytotoxic T cells (CTL, CD8+) and natural-killer cells (NK, CD3−/CD49B+) in RANCA tumor tissues. Combined with an anti-PD-1 antibody, olverembatinib increased CTLs, NK cells, dendritic cells (DCs, MHC-II+/CD11C+), and M1 macrophages (F4/80+/CD11B+/CD86+) in RANCA tumor tissues, indicating an immunoregulatory effect of olverembatinib. Taken together, these data suggest that combining olverembatinib with a CPI confers synergistic antitumor effects in an RCC cancer mouse model by targeting tumor growth, angiogenesis, and immune regulation. This novel combination may provide an alternative approach to enhance treatment effects with CPIs in renal cancers. Citation Format: Guangfeng Wang, Eric Liang, Ping Min, Huidan Yu, Bingxing Wu, Dajun Yang, Yifan Zhai. Olverembatinib (HQP1351) enhances antitumor effects of immunotherapy in renal cell carcinoma (RCC). [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5071.

Tumoral CD105 promotes immunosuppression, metastasis, and angiogenesis in renal cell carcinoma.

CD105 (endoglin) is a transmembrane protein that functions as a TGF-beta coreceptor and is highly expressed on endothelial cells. Unsurprisingly, preclinical and clinical evidence strongly suggests that CD105 is an important contributor to tumor angiogenesis and tumor progression. Emerging evidence suggests that CD105 is also expressed by tumor cells themselves in certain cancers such as renal cell carcinoma (RCC). In human RCC tumor cells, CD105 expression is associated with stem cell-like properties and contributes to the malignant phenotype in vitro and in xenograft models. However, as a regulator of TGF-beta signaling, there is a striking lack of evidence for the role of tumor-expressed CD105 in the anti-tumor immune response and the tumor microenvironment. In this study, we report that tumor cell-expressed CD105 potentiates both the in vitro and in vivo tumorigenic potential of RCC in a syngeneic murine RCC tumor model. Importantly, we find that tumor cell-expressed CD105 sculpts the tumor microenvironment by enhancing the recruitment of immunosuppressive cell types and inhibiting the polyfunctionality of tumor-infiltrating CD4+ and CD8+ T cells. Finally, while CD105 expression by endothelial cells is a well-established contributor to tumor angiogenesis, we also find that tumor cell-expressed CD105 significantly contributes to tumor angiogenesis in RCC.

Manipulation of Amino Acid Levels with Artificial Diets Induces a Marked Anticancer Activity in Mice with Renal Cell Carcinoma.

Targeted therapies with antiangiogenic drugs (e.g., sunitinib) and immune checkpoint inhibitors (e.g., anti-PD-1 antibodies) are the standard of care for patients with metastatic renal cell carcinoma. Although these treatments improve patient survival, they are rarely curative. We previously hypothesized that advanced cancers might be treated without drugs by using artificial diets in which the levels of specific amino acids (AAs) are manipulated. In this work, after showing that AA manipulation induces selective anticancer activity in renal cell carcinoma cells in vitro, we screened 18 artificial diets for anticancer activity in a challenging animal model of renal cell carcinoma. The model was established by injecting murine renal cell carcinoma (Renca) cells into the peritoneum of immunocompetent BALB/cAnNRj mice. Mice survival was markedly improved when their normal diet was replaced with our artificial diets. Mice fed a diet lacking six AAs (diet T2) lived longer than mice treated with sunitinib or anti-PD-1 immunotherapy; several animals lived very long or were cured. Controlling the levels of several AAs (e.g., cysteine, methionine, and leucine) and lipids was important for the anticancer activity of the diets. Additional studies are needed to further evaluate the therapeutic potential and mechanism of action of this simple and inexpensive anticancer strategy.

Listeria-based immunotherapy directed against CD105 exerts anti-angiogenic and anti-tumor efficacy in renal cell carcinoma

Targeting tumor-associated angiogenesis is currently at the forefront of renal cell carcinoma (RCC) therapy, with sunitinib and bevacizumab leading to increased survival in patients with metastatic RCC (mRCC). However, resistance often occurs shortly after initiation of therapy, suggesting that targeting the tumor-associated vascular endothelium may not be sufficient to eradicate RCC. This study reports the therapeutic efficacy of a Listeria (Lm)-based vaccine encoding an antigenic fragment of CD105 (Lm-LLO-CD105A) that targets both RCC tumor cells and the tumor-associated vasculature. Lm-LLO-CD105A treatment reduced primary tumor growth in both subcutaneous and orthotopic models of murine RCC. The vaccine conferred anti-tumor immunity and remodeled the tumor microenvironment (TME), resulting in increased infiltration of polyfunctional CD8+ and CD4+ T cells and reduced infiltration of immunosuppressive cell types within the TME. We further provide evidence that the therapeutic efficacy of Lm-LLO-CD105A is mediated by CD8+ T cells and is dependent on the robust antigenic expression of CD105 by RCC tumor cells. The result from this study demonstrates the safety and promising therapeutic efficacy of targeting RCC-associated CD105 expression with Lm-based immunotherapy.

Cabozantinib-Loaded PLGA Nanoparticles: A Potential Adjuvant Strategy for Surgically Resected High-Risk Non-Metastatic Renal Cell Carcinoma.

Patients with high-risk non-metastatic renal cell carcinoma (RCC) are at risk of metastatic relapse following nephrectomy. Cabozantinib (CZ), a potent multitarget tyrosine kinase inhibitor, interferes with angiogenesis and immunosuppression associated with surgery-induced metastasis. Here, we explored the therapeutic potential of CZ-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles (CZ-PLGA-NPs) as an adjuvant strategy for targeting post-nephrectomy metastasis. A clinically relevant subline recapitulating post-nephrectomy lung metastasis of high-risk human RCC, namely Renca-SRLu5-Luc, was established through in vivo serial selection of luciferase-expressing murine RCC Renca-Luc cells. CZ was encapsulated into PLGA-NPs via the conventional single emulsion technique. The multifaceted preclinical antimetastatic efficacy of CZ-PLGA-NPs was assessed in Renca-SRLu5-Luc cells. CZ-PLGA-NPs with a smooth surface displayed desirable physicochemical properties, good CZ encapsulation efficiency, as well as controlled and sustained CZ release. CZ-PLGA-NPs exhibited remarkable dose-dependent toxicity against Renca-SRLu5-Luc cells by inducing G2/M cell cycle arrest and apoptosis. CZ-PLGA-NPs attenuated in vitro colony formation, migration, and invasion by abrogating AKT and ERK1/2 activation. An intravenous injection of CZ-PLGA-NPs markedly reduced lung metastatic burden and prolonged lifespan with favorable safety in the Renca-SRLu5-Luc experimental lung metastasis model. The novel CZ-PLGA-NPs system with multifaceted antimetastatic effects and alleviating off-target toxicity potential is a promising adjunctive agent for patients with surgically resected high-risk RCC.

L-Serine-Modified Poly-L-Lysine as a Biodegradable Kidney-Targeted Drug Carrier for the Efficient Radionuclide Therapy of Renal Cell Carcinoma.

In the present study, L-serine (Ser)-modified poly-L-lysine (PLL) was synthesized to develop a biodegradable, kidney-targeted drug carrier for efficient radionuclide therapy in renal cell carcinoma (RCC). Ser-PLL was labeled with 111In/90Y via diethylenetriaminepentaacetic acid (DTPA) chelation for biodistribution analysis/radionuclide therapy. In mice, approximately 91% of the total dose accumulated in the kidney 3 h after intravenous injection of 111In-labeled Ser-PLL. Single-photon emission computed tomography/computed tomography (SPECT/CT) imaging showed that 111In-labeled Ser-PLL accumulated in the renal cortex following intravenous injection. An intrarenal distribution study showed that fluorescein isothiocyanate (FITC)-labeled Ser-PLL accumulated mainly in the renal proximal tubules. This pattern was associated with RCC pathogenesis. Moreover, 111In-labeled Ser-PLL rapidly degraded and was eluted along with the low-molecular-weight fractions of the renal homogenate in gel filtration chromatography. Continuous Ser-PLL administration over five days had no significant effect on plasma creatinine, blood urea nitrogen (BUN), or renal histology. In a murine RCC model, kidney tumor growth was significantly inhibited by the administration of the beta-emitter 90Y combined with Ser-PLL. The foregoing results indicate that Ser-PLL is promising as a biodegradable drug carrier for kidney-targeted drug delivery and efficient radionuclide therapy in RCC.

34P Addition of oncolytic virus is as effective as addition of cytoreductive nephrectomy to the first-line treatment of anti-PD-1/anti-CTLA-4 antibodies in the murine metastatic renal cell carcinoma model

The role of cytoreductive nephrectomy (CN) remains controversial in the era of advancement of new immunotherapeutic and targeted agents. We compared the therapeutic potential of JX-594 in combination with ipilimumab and nivolumab (ipi/nivo) which is the conventional first-line treatment settings of metastatic renal cell carcinoma (mRCC), with CN in two preclinical murine mRCC models.

Abstract 2116: VPS34 inhibitor SB02024 activates cGAS-STING signaling and sensitizes tumors to STING agonist

Abstract Novel approaches to reduce tumor immunosuppression and improve responses to anti-cancer immunotherapies based on immune-checkpoint inhibitors are needed. Emerging evidence demonstrates that autophagy inhibition enhances anti-tumor immunity by tumor cell-intrinsic and extrinsic mechanisms. Recently, we reported that pharmacological inhibition of VPS34 (PIK3C3), a lipid kinase regulating autophagy initiation, decreases tumor growth and improve the efficacy of anti-PD-1/PD-L1 therapy in melanoma and colorectal cancer mouse models. This effect was dependent on increasing T and NK cell infiltration as well as the expression of CCL5 and CXCL10 chemokines in the tumor microenvironment. Here, we explored the signaling mechanisms underlying the chemokine release following treatment with VPS34 inhibitor SB02024. We found that both pharmacological and RNAi-mediated inhibition of VPS34 activated a cGAS-STING-dependent type I interferon response in renal cell carcinoma (RCC) and melanoma cell lines. Furthermore, combination treatment of VPS34 inhibitor SB02024 with STING agonist ADU-S100 or cGAMP increased the mRNA expression and release of proinflammatory cytokines in human and murine RCC and melanoma cancer cell lines. Oral administration of SB02024 in combination with intratumoral injections of ADU-S100 significantly decreased tumor growth and weight and improved mice survival of B16-F10 tumor-bearing mice. Taken together, our data demonstrates that targeting of VPS34 results in a cGAS/STING-mediated increase of pro-inflammatory cytokine secretion and synergizes with a STING agonist. We believe that systemic VPS34 inhibition using SB02024 would be of major interest in combination or as an alternative to STING agonists to improve anti-tumor immune responses. Citation Format: Yasmin Yu, Muhammad Z. Noman, Santiago Parpal, Simone C. Kleinendorst, Kristine B. Saether, Andrey Alexeyenko, Jenny Viklund, Martin Andersson, Jessica Martinsson, Katja P. Tamm, Angelo De Milito, Bassam Janji. VPS34 inhibitor SB02024 activates cGAS-STING signaling and sensitizes tumors to STING agonist [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2116.

Abstract 95: In vitro, in vivo and molecular effects of triptolide and minnelide in renal cell carcinoma

Abstract Background: The worldwide incidence of Renal Cell Carcinoma (RCC) is increasing. Although new therapies have improved outcomes in advanced RCC, most patients eventually fail treatment and succumb to this devastating disease. Systemic therapy strategies have focused on TKI and immunotherapy, alone or in combination. Triptolide, a diterpenoid epoxide extracted from Tripterygium wilfordii Hook f (TWHf), has potent antitumor activity in multiple cancer models. Few studies have focused on the potential of triptolide as a novel therapeutic option in RCC. Objective: the objectives of this study are to characterize the in vitro and in vivo effects of Triptolide (T) and its water-soluble form, Minnelide (M), in models of renal cell carcinoma. Methods: The in vitro effects of triptolide (T) on human and murine RCC (786-0, A498, Caki-1, ACHN, and RENCA) cell proliferation was assessed using cell count and xCelligence assays at 24, 48, 72 and 96h. Molecular and mechanistic characterization of triptolide’s effects in 786-0 cells were analyzed by the (Reverse Phase Protein Array) and validated by western blot analysis. The in vivo effects (tumor progression and survival) of M were assessed in nude mice bearing 786-0 tumors (8x106 cells per mouse). M was administered to tumor-bearing mice at two different doses (0.21mg/kg and 0.42mg/kg daily), intraperitoneally, for 21 days. Correlative studies to explain the in vivo effect of M and the correlation with the molecular changes in vitro seen are being performed and will be shown in the poster. Results: T significantly inhibited, in a dose-response manner, cell proliferation in all human and murine renal cancer cell lines, with IC50 ranging between 12.5 and 25 nM). T was associated with significant negative modulation of proliferation, cell cycle, survival, increased apoptosis, and ER stress pathways in 786-0 cells, as demonstrated by RPPA analysis and validated by western Blot of selected pathway proteins, such as apoptosis (PARP cleavage and Caspase 3 activation), ER stress induction (pEIF2a, CHOP), and down-regulation of survival and proliferation pathways (pAKT). In vivo, M was associated with significant antitumor effects in 786-0 xenografts, with complete responses in the majority of mice while on treatment. These effects were associated with significant prolongation in overall survival in M treated vs. control mice. No significant toxicity or treatment-related deaths were observed. Conclusion: Our results have shown for the first time the potent in vitro and in vivo antitumor effects of T in RCC and the molecular changes associated with these effects. The profound antitumor effects in the aggressive 786-0 RCC xenograft model are highly encouraging and warrant further preclinical studies and potential clinical trials of M this devastating disease. Correlative tumor studies to understand the mechanisms of M in vivo antitumor effects are underway and will be presented at the meeting. Citation Format: Valery A. Chavez, Floritza Bustamante, Abner Murray, Ashok Saluja, Jaime Merchan. In vitro, in vivo and molecular effects of triptolide and minnelide in renal cell carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 95.

Anti-4-1BB antibody-based combination therapy augments antitumor immunity by enhancing CD11c+CD8+ T cells in renal cell carcinoma.

To improve the potential treatment strategies of incurable renal cell carcinoma (RCC), which is highly resistant to chemotherapy and radiotherapy, the present study established a combination therapy with immunostimulatory factor (ISTF) and anti-4-1BB monoclonal antibodies (mAbs) to augment the antitumor response in a murine RCC model. ISTF isolated from Actinobacillus actinomycetemcomitans stimulates macrophages, dendritic cells and B cells to produce IL-6, TNF-α, nitric oxide and major histocompatibility complex class II expression. 4-1BB (CD137) is expressed in activated immune cells, including activated T cells, and is a promising target for cancer immunotherapy. The administration of anti-4-1BB mAbs promoted antitumor immunity via enhancing CD11c+CD8+ T cells. The CD11c+CD8+ T cells were characterized by high killing activity and IFN-γ-producing ability, representing a phenotype of active effector cytotoxic T lymphocytes. The present study showed that combination therapy with ISTF and anti-4-1BB mAbs promoted partial tumor regression with established RCC, but monotherapy with ISTF or anti-4-1BB mAbs did not. These effects were speculated to be caused by the increase in CD11c+CD8+ T cells in the spleen and tumor, and IFN-γ production. These insights into the effector mechanisms of the combination of ISTF and anti-4-1BB mAbs may be useful for targeting incurable RCC.

Kidney injury molecule-1 inhibits metastasis of renal cell carcinoma

Metastasis is present in approximately 30% of patients diagnosed with renal cell carcinoma (RCC) and is associated with a 5-year survival rate of < 15%. Kidney injury molecule 1 (KIM-1), encoded by the HAVCR1 gene, is a proximal tubule cell-surface glycoprotein and a biomarker for early detection of RCC, but its pathophysiological significance in RCC remains unclear. We generated human and murine RCC cell lines either expressing or lacking KIM-1, respectively, and compared their growth and metastatic properties using validated methods. Surprisingly, KIM-1 expression had no effect on cell proliferation or subcutaneous tumour growth in immune deficient (Rag1−/−) Balb/c mice, but inhibited cell invasion and formation of lung metastasis in the same model. Further, we show that the inhibitory effect of KIM-1 on metastases was observed in both immune deficient and immune competent mice. Transcriptomic profiling identified the mRNA for the pro-metastatic GTPase, Rab27b, to be downregulated significantly in KIM-1 expressing human and murine RCC cells. Finally, analysis of The Cancer Genome Atlas (TCGA) data revealed that elevated HAVCR1 mRNA expression in the two most common types of RCC, clear cell and papillary RCC, tumours correlated with significantly improved overall patient survival. Our findings reveal a novel role for KIM-1 in inhibiting metastasis of RCC and suggests that tumour-associated KIM-1 expression may be a favourable prognostic factor.

Tyrosine Kinase Inhibitor Cabozantinib Inhibits Murine Renal Cancer by Activating Innate and Adaptive Immunity

BackgroundAdvanced renal cell carcinoma (RCC) has a very dismal prognosis. Cabozantinib, a tyrosine kinase inhibitor, has been approved for the treatment of advanced RCC. However, the impact of cabozantinib on the immune microenvironment of RCC remains poorly understood.MethodsKaplan-Meier survival curves were constructed to examine the correlation between intratumor infiltration of neutrophils and patient prognosis in RCC. Infiltration and effector function of neutrophils and T cells in response to cabozantinib treatment were investigated in a murine RCC model.ResultsA retrospective study of 307 RCC patients indicated that neutrophils were recruited into tumor tissues, and increased neutrophil infiltration was associated with improved clinical outcomes. In a murine model of RCC, cabozantinib treatment significantly increased both intratumor infiltration and anti-tumor function of neutrophils and T cells. Mechanistically, we found that cabozantinib treatment induced expression of neutrophil-related chemokines (CCL11 and CXCL12) and T cell-related chemokines (CCL8 and CX3CL1) in the tumor microenvironment. Furthermore, depletion of neutrophils and CD8+ T cells compromised the therapeutic efficacy of cabozantinib. Importantly, cabozantinib treatment induced long-term anti-tumor T cell response.ConclusionsOur study revealed novel mechanisms of the therapeutic effects of cabozantinib on RCC by activating both neutrophil-mediated innate immunity and T cell-mediated adaptive immunity. These findings are of great significance for guiding the clinical use of cabozantinib and provide a good candidate for future combination therapy with T-cell therapies or other immunotherapies.

Development of a highly pulmonary metastatic orthotopic renal cell carcinoma murine model.

ABSTRACTThe incidence of renal cell carcinoma (RCC) is high, and its outcomes remain poor. Mortality is attributable largely to metastatic disease and a dearth of effective therapeutic interventions. The lungs are the most common metastatic site. To elucidate the biological mechanisms underlying pulmonary metastasis and identify superior therapeutic strategies, we developed a novel and clinically relevant murine RCC model exhibiting enhanced pulmonary metastasis. Mice underwent intrarenal implantation using luciferase-expressing Renca, a murine renal adenocarcinoma cell line. Primary renal tumor progression and development of metastatic lung lesions were monitored in live mice using bioluminescent imaging, followed by post-mortem organ assessment. Cells were isolated from pulmonary metastases for reimplantation, followed by repeat monitoring and assessment. This process was repeated once more for a total of two in vivo passages to select for pulmonary metastatic Renca cell subpopulations. However, a single round of in vivo selection was sufficient to produce a near-maximally metastatic subpopulation. Relative to Renca cell-implanted mice, subpopulation-implanted mice exhibited shorter implantation-metastasis intervals (5 days), shorter implantation-moribundity intervals (sacrificed at 18.6±2.9 versus 22.3±1.1 days), a higher number of metastatic lung lesions at 23 days (183.9±39.0 versus 172.6±38.2) and poorer survival. Implantation of cells derived from the second round of in vivo selection produced no further significant differences in the above metrics. This model consistently and efficiently recapitulates RCC pulmonary metastasis while allowing in vivo monitoring of tumor progression, thereby facilitating elucidation of the molecular mechanisms underlying pulmonary metastasis and evaluation of therapeutic modalities.

Modeling hyperpolarized lactate signal dynamics in cells, patient-derived tissue slice cultures and murine models.

Determining the aggressiveness of renal cell carcinoma (RCC) noninvasively is a critical part of the diagnostic workup for treating this disease that kills more than 15,000 people annually in the USA. Recently, we have shown that not only the amount of lactate produced, as a consequence of the Warburg effect, but also its efflux out of the cell, is a critical marker of RCC aggressiveness and differentiating RCCs from benign renal tumors. Enzymatic conversions can now be measured in situ with hyperpolarized (HP) 13 C magnetic resonance (MR) on a sub-minute time scale. Using RCC models, we have shown that this technology can interrogate in real time both lactate production and compartmentalization, which are associated with tumor aggressiveness. The dynamic HP MR data have enabled us to robustly characterize parameters that have been elusive to measure directly in intact living cells and murine tumors thus far. Specifically, we were able to measure the same intracellular lactate longitudinal relaxation time in three RCC cell lines of 16.42 s, and lactate efflux rate ranging from 0.14 to 0.8 s-1 in the least to the most aggressive RCC cell lines and correlate it to monocarboxylate transporter isoform 4 expression. We also analyzed dynamic HP lactate and pyruvate data from orthotopic murine RCC tumors using a simplified one-compartment model, and showed comparable apparent pyruvate to lactate conversion rate (kPL ) values with those measured in vitro. This kinetic modeling was then extended to characterize the lactate dynamics in patient-derived living RCC tissue slices; and even without direct measurement of the extracellular lactate signal the efflux parameter was still assessed and was distinct between the benign renal tumors and RCCs. Across all these preclinical models, the rate parameters of kPL and lactate efflux correlated to cancer aggressiveness, demonstrating the validity of our modeling approach for noninvasive assessment of RCC aggressiveness.

Abstract 6637: Inhibition of FGFR signaling by lenvatinib activates tumor interferon gamma signaling pathway and potentiates antitumor activity of anti-PD-1 antibody

Abstract Background: Lenvatinib mesilate (LEN) is an oral multiple receptor tyrosine kinase (RTK) inhibitor that selectively inhibits the kinase activity of VEGFR1-3, in addition to other proangiogenic and oncogenic pathway-related RTKs including FGFR1-4; PDGFRα; KIT; and RET. To improve the efficacy of immune checkpoint inhibitors (ICI), combination treatments of ICI plus anti-angiogenic inhibitors are currently under investigation. Lenvatinib plus pembrolizumab is approved for 2nd line treatment of advanced endometrial carcinoma that is not microsatellite instability-high or mismatch repair deficient in the US, and several Ph3 clinical trials with this combination are ongoing. Immunosuppressive roles of VEGF in tumor microenvironment have been well studied; however, immunomodulatory effects of FGFR signaling and the effect of FGFR inhibition on antitumor activity of anti-PD-1 antibody (PD-1 Ab) are still largely unknown. In this study, we investigated mechanism of action underlying the activity of LEN and PD-1 blockade in syngeneic mouse renal cell carcinoma (RCC) model. We also explored the relationship between FGFR signaling and interferon (IFN) γ signaling pathway in cancer cells, and examined whether LEN has an impact on IFNγ pathway by FGFR inhibition. Methods: We examined antitumor activity of combination treatment of LEN at 10 mg/kg (po, qd) plus PD-1 Ab at 10 mg/kg (ip, twice weekly) and VEGF-selective inhibitor axitinib (Axi) at 10 mg/kg (po, bid) plus PD-1 Ab in the RAG (murine RCC cell) subcutaneous tumor model. Gene expression profile in tumor tissues or cultured cells was analyzed by qRT-PCR or RNA seq. FGFR and IFNγ signaling pathways and their downstream molecules in tumor tissues and cultured cells were analyzed by western blot (WB) and immunofluorescence (IF). Results: In the RAG model, the combination of LEN and PD-1 Ab showed greater tumor response than each single treatment and Axi plus PD-1 Ab combination. In the tumors, WB analysis revealed LEN treatment increased STAT1 phosphorylation and PD-L1 expression and decreased the expression of SOCS1, a suppressor molecule of JAK-STAT signaling. Increased expression of PD-L1 was also observed in the tumors by IF analysis. WB and qRT-PCR analyses elucidated that activation of FGFR signaling pathway inhibited the induction of B2M, PD-L1 and CXCL10 expression in RAG cells and human cancer cell lines. Inhibition of FGFR by LEN treatment reactivated the IFNγ signaling pathway. Conclusion: Dual inhibition of VEGFR and FGFR signaling by LEN may exert the greater antitumor activity via activation of IFNγ pathway compared with single inhibition of VEGFR signaling in combination with PD-1 Ab. These results provide one of unique mechanisms of antitumor activity of LEN as VEGFR and FGFR inhibitor in combination with PD-1 blockade in preclinical models. Citation Format: Yusuke Adachi, Hiroshi Kamiyama, Kenji Ichikawa, Yoichi Ozawa, Sayo Fukushima, Satoshi Goda, Shogo Yamaguchi, Masahiro Matsuki, Saori Watanabe Miyano, Akira Yokoi, Yu Kato, Yasuhiro Funahashi. Inhibition of FGFR signaling by lenvatinib activates tumor interferon gamma signaling pathway and potentiates antitumor activity of anti-PD-1 antibody [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6637.

Nucleobindin-2 enhances the epithelial-mesenchymal transition in renal cell carcinoma.

Nucleobindin 2 (NUCB-2) is a multifunctional protein that contains several functional domains and is associated with a wide variety of biological processes, such as food intake and energy homeostasis. NUCB-2 has been demonstrated to be associated with worse malignant outcomes and cell migration in breast and prostate cancer. However, to the best of our knowledge, its clinical and biological significance in renal cell carcinoma remains unknown. In the present study, tissue specimens from 68 patients with renal cell carcinoma and 10 normal controls were collected for NUCB-2 mRNA and protein assays. The NUCB-2 level in the patients with renal cell cancer was significantly increased compared with the normal control patients. NUCB-2-knockout in the renal cancer cell line SK-RC-52 inhibited migration and invasion. In addition, the expression levels of molecules associated with epithelial-mesenchymal transition (EMT), including E-cadherin, β-catenin, Slug and Twist, were affected by NUCB-2 suppression and the zinc finger E-box binding to homeobox 1 (ZEB1)-dependent pathway. The AMP-dependent protein kinase (AMPK)/target of rapamycin complex (mTORC) 1 signaling pathway participates in the regulation of NUCB-2-mediated metastasis and EMT. Suppression of NUCB-2 also inhibited tumor nodule formation in a murine renal cell carcinoma tumor model. In summary, NUCB-2 increased migration, invasion and EMT in renal cell carcinoma cells through the AMPK/TORC1/ZEB1 pathway in vitro and in vivo.

Abstract 2242: Roles of FGFR inhibition on murine RCC cells in combination antitumor activity of lenvatinib with anti-PD1 antibody via regulatingIFN gamma signaling pathway

Abstract Lenvatinib mesilate (LEN) is an oral multiple receptor tyrosine kinase (RTK) inhibitor that selectively inhibits the kinase activities of VEGFR1-3, in addition to other proangiogenic and oncogenic pathway-related RTKs including FGFR1-4; PDGFRα; KIT; and RET. LEN plus everolimus for advanced renal cell carcinoma (RCC) after one prior anti-VEGF therapy was approved in the US and EU in 2016. Currently, Phase1b/2 clinical trial of LEN in combination with pembrolizumab with selected solid tumors including RCC and Phase3 study of LEN in combination with everolimus or pembrolizumab for metastatic RCC patients are in progress. In this study, we investigated the antitumor and immunomodulatory activities of LEN alone and in combination with anti-PD1 Ab and explored the mechanism of action underlying the activities of LEN and PD1 blockade in preclinical syngeneic RCC models. We examined antitumor activity of combination treatment of LEN at 10 mg/kg (po, qd) and anti-PD1 Ab at 10 mg/kg (ip, twice weekly) in the murine subcutaneous RCC model using RAG cell line. Immune cell population analyses in tumor tissues were performed by flow cytometer. Immune-related gene expression profile in tumor tissues or cultured cells was analyzed by qPCR and RNA seq. Effects on FGFR and IFN gamma (IFNγ) signaling pathways and their downstream molecules in cultured cells were analyzed by western blot. In the murine syngeneic RAG tumor model, the combination treatment of LEN and anti-PD1 Ab showed tumor shrinkage, and some of tumors were regressed to nonpalpable sizes with long duration of response. LEN alone and in combination with anti-PD1 Ab significantly decreased the population of tumor associated macrophage in tumor tissues by FCM analysis. Gene expression analysis for immune cell responses in tumor tissues revealed the upregulation of IFNγ and its downstream genes including PD-L1 with combination of LEN and anti-PD1 Ab. Western blot analysis elucidated that FGFR signaling pathway inhibited the activation of IFNγ signaling pathway and the induction of PD-L1 expression in murine RCC cells, and LEN-treatment reactivated the IFNγ signaling pathway by inhibition of FGFR signaling. Combination of LEN and anti-PD1 Ab showed greater antitumor activity including tumor shrinkage with long duration of response in the murine RCC model. Modulation of immune microenvironment by LEN and combination of LEN with PD1 Ab may underlie the strong antitumor activity in preclinical RCC model. Inhibitory activity of LEN against FGFR reactivated the IFNγ pathway and PD-L1 expression suppressed by activation of FGFR signaling pathway, and this inhibitory activity of LEN may potentiate the antitumor activity of combination treatments with anti-PD1 Ab. These preclinical results provide one of the unique mechanisms of combinational effect of LEN with PD1 blockade in the preclinical RCC model. Citation Format: Yusuke Adachi, Kenji Ichikawa, Yu Kato, Yasuhiro Funahashi. Roles of FGFR inhibition on murine RCC cells in combination antitumor activity of lenvatinib with anti-PD1 antibody via regulatingIFN gamma signaling pathway [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2242.