Hypertension in Young Adults: Think Juxtaglomerular Cell Tumor!

Introduction/Objective

Juxtaglomerular cell tumor is a benign, renin-secreting neoplasm. The tumor arises from the juxtaglomerular apparatus cells of the kidney. Because the tumor is hormonally active, patients usually suffer from hypokalemia, hyperaldosteronism, and hypertension. The typical patient population is adolescents and young adults with slight female predominance. Herein, we describe a case of a 19-year-old Asian female with a somewhat atypical presentation.

Methods/Case Report

A 19-year-old Asian female presented with upper extremity weakness, numbness, and tingling. On physical examination, the only notable finding was hypertension. Extensive work up reveled an aldosterone level of 71 nanograms per deciliter and plasma renin activity of 6.25 nanograms per milliliter per hour. A CT scan of the abdomen revealed a 2.4cm mass in the lower pole of the left kidney. The mass was resected by partial nephrectomy. Sectioning of the specimen revealed a 2.4cm well-circumscribed, encapsulated tumor. On microscopic evaluation, the tumor had glomoid appearance with sheets of uniform, round to polygonal cells with clear to eosinophilic cytoplasm. The stroma was scanty, mitoses were rare, and necrosis was not identified. Immunohistochemical stains showed the tumor cells to be positive for CD117, CD34, Cathepsin K, Synaptophysin, and CD10 and negative for ER, PR, CK7, PAX-8, pancytokeratin, EMA, S100, Melan-A, HMB45, SMA and CAIX. Diagnosis of Juxtaglomerular cell tumor was rendered. The patient was alive and well and without signs of recurrence 14 months after surgery.

Results (if a Case Study enter NA)

NA.

Conclusion

This case highlights the importance of a regular physical exam and having a high index of suspicion in patients presenting with unusual complaints.

NKTR-255, a novel polymer-conjugated rhIL-15 with potent antitumor efficacy

BACKGROUND

NKTR-255 is a novel polyethylene glycol-conjugate of recombinant human interleukin-15 (rhIL-15), which was designed to retain all known receptor binding interactions of the IL-15 molecule. We explored the biologic and pharmacologic differences between endogenous IL-15 receptor α (IL-15Rα)-dependent (NKTR-255 and rhIL-15) and IL-15Rα-independent (precomplexed rhIL-15/IL-15Rα) cytokines.

METHODS

In vitro pharmacological properties of rhIL-15, NKTR-255 and precomplex cytokines (rhIL-15/IL-15Rα and rhIL-15 N72D/IL-15Rα Fc) were investigated in receptor binding, signaling and cell function. In vivo pharmacokinetic (PK) and pharmacodynamic profile of the cytokines were evaluated in normal mice. Finally, immunomodulatory effect and antitumor activity were assessed in a Daudi lymphoma model.

RESULTS

NKTR-255 and rhIL-15 exhibited similar in vitro properties in receptor affinity, signaling and leukocyte degranulation, which collectively differed from precomplexed cytokines. Notably, NKTR-255 and rhIL-15 stimulated greater granzyme B secretion in human peripheral blood mononuclear cells versus precomplexed cytokines. In vivo, NKTR-255 exhibited a PK profile with reduced clearance and a longer half-life relative to rhIL-15 and demonstrated prolonged IL-15R engagement in lymphocytes compared with only transient engagement observed for rhIL-15 and precomplexed rhIL-15 N72D/IL-15Rα Fc. As a consequent, NKTR-255 provided a durable and sustained proliferation and activation of natural killer (NK) and CD8+ T cells. Importantly, NKTR-255 is more effective than the precomplexed cytokine at inducing functionally competent, cytotoxic NK cells in the tumor microenvironment and the properties of NKTR-255 translated into superior antitumor activity in a B-cell lymphoma model versus the precomplexed cytokine.

CONCLUSIONS

Our results show that the novel immunotherapeutic, NKTR-255, retains the full spectrum of IL-15 biology, but with improved PK properties, over rhIL-15. These findings support the ongoing phase 1 first-in-human trial (NCT04136756) of NKTR-255 in participants with relapsed or refractory hematologic malignancies, potentially advancing rhIL-15-based immunotherapies for the treatment of cancer.

Bempegaldesleukin (BEMPEG; NKTR-214) efficacy as a single agent and in combination with checkpoint-inhibitor therapy in mouse models of osteosarcoma

Survival of patients with relapsed/refractory osteosarcoma has not improved in the last 30 years. Several immunotherapeutic approaches have shown benefit in murine osteosarcoma models, including the anti-programmed death-1 (anti-PD-1) and anti-cytotoxic T-lymphocyte antigen-4 (anti-CTLA-4) immune checkpoint inhibitors. Treatment with the T-cell growth factor interleukin-2 (IL-2) has shown some clinical benefit but has limitations due to poor tolerability. Therefore, we evaluated the efficacy of bempegaldesleukin (BEMPEG; NKTR-214), a first-in-class CD122-preferential IL-2 pathway agonist, alone and in combination with anti-PD-1 or anti-CTLA-4 immune checkpoint inhibitors in metastatic and orthotopic murine models of osteosarcoma. Treatment with BEMPEG delayed tumor growth and increased overall survival of mice with K7M2-WT osteosarcoma pulmonary metastases. BEMPEG also inhibited primary tumor growth and metastatic relapse in lungs and bone in the K7M3 orthotopic osteosarcoma mouse model. In addition, it enhanced therapeutic activity of anti-CTLA-4 and anti-PD-1 checkpoint blockade in the DLM8 subcutaneous murine osteosarcoma model. Finally, BEMPEG strongly increased accumulation of intratumoral effector T cells and natural killer cells, but not T-regulatory cells, resulting in improved effector:inhibitory cell ratios. Collectively, these data in multiple murine models of osteosarcoma provide a path toward clinical evaluation of BEMPEG-based regimens in human osteosarcoma.

Abstract 1603: NKTR-255 engages the IL-15 pathway driving CD8 T cell survival and CD8 memory T cell proliferation

Background: IL-15, an immunostimulatory cytokine, plays an important role in both the innate and adaptive immune system. Notably, this pleiotropic cytokine is a key regulator of homeostasis and survival of CD8 and CD8 memory T cells. Targeting the IL-15 pathway has therefore become a promising therapeutic approach in oncology through the induction of long-term T cell activation and durable memory responses. NKTR-255 is a polymer-engineered IL-15 that as a single-agent reduces tumor burden in various tumor models. Here, we show that the anti-tumor effects of NKTR-255 can be attributed to its modulation of survival and proliferation of CD8 and memory CD8 T cells.

Methods: Immunophenotyping of CD8 T cell subpopulations was performed in naïve and tumor-bearing Balb/c mice treated with NKTR-255. Cell surface staining of CD3, CD8, CD44, CD62L and Sca-1 was conducted to identify effector (Tem), central (Tcm) and stem (Tscm) memory T cells. Intracellular staining of Ki67 and Bcl-2 were also analyzed by flow cytometry. Human whole blood and PBMCs were stimulated with IL-15 (0.0001-1000ng/ml) or NKTR-255 (0.001-10,000ng/ml). At various time points pSTAT5 response in CD3, CD4, CD8 and NK (CD56 bright and dim) cells was monitored by flow cytometry.

Results: In naive mice, single dose NKTR-255 (dose range 0.06-1mg/kg) increased the proliferation of Tem, Tcm and Tscm CD8 T cells in a dose-dependent manner. Treatment at 0.3 and 1mg/kg dose levels increased proliferation at least 4 fold across the CD8 memory populations. The abundance of CD8 and CD8 memory T cells was still apparent 6 days post-treatment unlike single dose IL-15 which was ineffective. In a CT-26 lung metastasis model, NKTR-255 reduced the number of lung nodules in a dose-dependent manner. A 0.3mg/kg dose level increased Bcl-2 MFI 1.5 fold in CD8 T cells. Furthermore, administration of NKTR-255 at 0.3, 1 or 3mg/kg significantly increased CD8 proliferation in a dose-dependent manner in blood (1.7, 4.6 and 5.3 fold) and spleen (2.5, 5.7 and 6.9 fold) compared to vehicle. The enhanced Bcl-2 expression and CD8 proliferation were accompanied by elevated CD8 T cells in blood (1.5, 2.4, and 3.4 fold increase) and spleen (1.3, 1.7 and 2.3 fold increase). Consistent with increased proliferation and increased Bcl-2 levels observed in vivo, both IL-15 and NKTR-255 showed dose-dependent induction of pSTAT5, a modulator of Bcl-2 expression, in CD4 and CD8 T cells from human whole blood and PBMCs.

Conclusions: NKTR-255 effectively engages the IL-15 pathway as evidenced by its strong induction of CD8 and memory CD8 T cell proliferation and promotion of survival. Combined with sustained activity and potency in human blood and PBMCs, our results support NKTR-255 as a novel tumor immunotherapeutic with great potential.

Citation Format: Peiwen Kuo, Mekhala Maiti, Phi Quach, Murali Addepalli, Arunasree Lanka, Poornachandra Mathamsetti, Christie Fanton, Ping Zhang, Peter Kirk, Takahiro Miyazaki, Jonathan Zalevsky. NKTR-255 engages the IL-15 pathway driving CD8 T cell survival and CD8 memory T cell proliferation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1603. doi:10.1158/1538-7445.AM2017-1603

Iron Chelators: Development of Novel Compounds with High and Selective Anti-Tumour Activity

Targeting essential nutrients (eg., those required for DNA synthesis) to inhibit cancer cell growth is a well established therapeutic strategy. A good example is the highly successful folate antagonist, methotrexate. However, up until recently, strategies to target iron which is also crucial for DNA synthesis have not been systematically explored to develop agents for the treatment of cancer. Over the last 15 years, our laboratory has embarked upon structure-activity studies designed to develop novel Fe chelators with anti-cancer efficacy. These studies have led to the development of the dipyridyl thiosemicarbazone chelators that show potent and selective anti-cancer activity and which overcome resistance to other cytotoxic agents. This class of compounds include the chelator, di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT), which at optimal doses markedly inhibits tumour growth and is well tolerated. Moreover, this ligand does not induce overt Fe-depletion in vivo, probably because very low doses (0.4 mg/kg) are effective at inhibiting tumour growth. Importantly, our compounds are far more active and less toxic than the chelator, Triapine®, that is being assessed in a wide variety of international clinical trials. A vital part of the mechanism of action of these compounds is their ability to form a redox-active Fe complex that generates radicals to inhibit tumour growth. Due to their relatively high lipophilicity and low molecular weight of this class of compounds, oral activity may be expected in addition to their well known efficacy via the intravenous route.