Exploiting docetaxel-induced tumor cell necrosis with tumor targeted delivery of IL-12

There is strong evidence that chemotherapy can induce tumor necrosis which can be exploited for the targeted delivery of immuno-oncology agents into the tumor microenvironment (TME). We hypothesized that docetaxel, a chemotherapeutic agent that induces necrosis, in combination with the bifunctional molecule NHS-IL-12 (M9241), which delivers recombinant IL-12 through specific targeting of necrotic regions in the tumor, would provide a significant antitumor benefit in the poorly inflamed murine tumor model, EMT6 (breast), and in the moderately immune-infiltrated tumor model, MC38 (colorectal). Docetaxel, as monotherapy or in combination with NHS-IL-12, promoted tumor necrosis, leading to the improved accumulation and retention of NHS-IL-12 in the TME. Significant antitumor activity and prolonged survival were observed in cohorts receiving docetaxel and NHS-IL-12 combination therapy in both the MC38 and EMT6 murine models. The therapeutic effects were associated with increased tumor infiltrating lymphocytes and were dependent on CD8+ T cells. Transcriptomics of the TME of mice receiving the combination therapy revealed the upregulation of genes involving crosstalk between innate and adaptive immunity factors, as well as the downregulation of signatures of myeloid cells. In addition, docetaxel and NHS-IL-12 combination therapy effectively controlled tumor growth of PD-L1 wild-type and PD-L1 knockout MC38 in vivo, implying this combination could be applied in immune checkpoint refractory tumors, and/or tumors regardless of PD-L1 status. The data presented herein provide the rationale for the design of clinical studies employing this combination or similar combinations of agents.

Overcoming hypoxia-induced functional suppression of NK cells

BACKGROUND

Natural killer (NK) cells are immune cells capable of killing virally infected cells and tumor cells without the need for antigen stimulation. Tumors, however, can create a suppressive microenvironment that decreases NK function. A feature of many tumors is hypoxia (low oxygen perfusion), which has been previously shown to decrease NK function. A high affinity NK (haNK) cell has been engineered to express a high affinity CD16 receptor as well as internal interleukin (IL)-2 for increased antibody-dependent cellular cytotoxicity (ADCC) and activation, respectively. We sought to investigate the tolerance of NK cells versus haNK cells to hypoxia.

METHODS

We exposed healthy donor (HD) NK and X-irradiated haNK cells to normoxia (20% oxygen) as well as hypoxia (0% oxygen) and investigated their ability to kill prostate, breast and lung tumor cell lines after 5 hours. We also used monoclonal antibodies cetuximab (anti-EGFR) or avelumab (antiprogrammed death-ligand 1) to investigate the effects of hypoxia on NK ADCC. Genomic and proteomic analyzes were done to determine the effect of hypoxia on the expression of factors important to NK cell function.

RESULTS

While HD NK cell cytolytic abilities were markedly and significantly impaired under hypoxic conditions, haNK cells maintained killing capacity under hypoxic conditions. NK killing, serial killing and ADCC were maintained under hypoxia in haNK cells. IL-2 has been previously implicated in serial killing and perforin regeneration and thus the endogenous IL-2 produced by haNK cells is likely a driver of the maintained killing capacity of haNK cells under hypoxic conditions. Activation of signal transducer and activator of transcription 3 (STAT3) is not seen in haNKs under hypoxia but is significant in HD NK cells. Pharmaceutical activation of STAT3 in haNKs led to reduced killing, implicating active STAT3 in reduced NK cell function.

CONCLUSIONS

In contrast to HD NK cells, haNK cells are resistant to acute hypoxia. The potent cytolytic function of haNK cells was maintained in an environment comparable to what would be encountered in a tumor. The data presented here provide an additional mechanism of action for haNK cells that are currently being evaluated in clinical trials for several tumor types.

PD-L1 targeting high-affinity NK (t-haNK) cells induce direct antitumor effects and target suppressive MDSC populations

Background

Although immune checkpoint inhibitors have revolutionized cancer treatment, clinical benefit with this class of agents has been limited to a subset of patients. Hence, more effective means to target tumor cells that express immune checkpoint molecules should be developed. For the first time, we report a novel natural killer (NK) cell line, programmed death-ligand 1 (PD-L1) targeting high-affinity natural killer (t-haNK), which was derived from NK-92 and was engineered to express high-affinity CD16, endoplasmic reticulum-retained interleukin (IL)-2, and a PD-L1-specific chimeric antigen receptor (CAR). We show that PD-L1 t-haNK cells also retained the expression of native NK receptors and carried a high content of granzyme and perforin granules.

Methods

NanoString, flow cytometry, and immunofluorescence analyses were performed to characterize the phenotype of irradiated PD-L1 t-haNK cells. In vitro PD-L1 t-haNK cell activity against cancer cell lines and human peripheral blood mononuclear cells (PBMCs) was determined via flow-based and ¹¹¹In-release killing assays. The antitumor effect of PD-L1 t-haNK cells in vivo was investigated using MDA-MB-231, H460, and HTB1 xenograft models in NOD-scid IL2Rgamma^null (NSG) mice. Additionally, the antitumor effect of PD-L1 t-haNK cells, in combination with anti-PD-1 and N-803, an IL-15 superagonist, was evaluated using mouse oral cancer 1 syngeneic model in C57BL/6 mice.

Results

We show that PD-L1 t-haNK cells expressed PD-L1-targeting CAR and CD16, retained the expression of native NK receptors, and carried a high content of granzyme and perforin granules. In vitro, we demonstrate the ability of irradiated PD-L1 t-haNK cells to lyse 20 of the 20 human cancer cell lines tested, including triple negative breast cancer (TNBC) and lung, urogenital, and gastric cancer cells. The cytotoxicity of PD-L1 t-haNK cells was correlated to the PD-L1 expression of the tumor targets and can be improved by pretreating the targets with interferon (IFN)-γ. In vivo, irradiated PD-L1 t-haNK cells inhibited the growth of engrafted TNBC and lung and bladder tumors in NSG mice. The combination of PD-L1 t-haNK cells with N-803 and anti-PD-1 antibody resulted in superior tumor growth control of engrafted oral cavity squamous carcinoma tumors in C57BL/6 mice. In addition, when cocultured with human PBMCs, PD-L1 t-haNK cells preferentially lysed the myeloid-derived suppressor cell population but not other immune cell types.

Conclusion

These studies demonstrate the antitumor efficacy of PD-L1 t-haNK cells and provide a rationale for the potential use of these cells in clinical studies.

Therapy of Established Tumors with Rationally Designed Multiple Agents Targeting Diverse Immune-Tumor Interactions: Engage, Expand, Enable

Immunotherapy of immunologically cold solid tumors may require multiple agents to engage immune effector cells, expand effector populations and activities, and enable immune responses in the tumor microenvironment (TME). To target these distinct phenomena, we strategically chose five clinical-stage immuno-oncology agents, namely, (i) a tumor antigen-targeting adenovirus-based vaccine (Ad-CEA) and an IL15 superagonist (N-803) to activate tumor-specific T cells, (ii) OX40 and GITR agonists to expand and enhance the activated effector populations, and (iii) an IDO inhibitor (IDOi) to enable effector-cell activity in the TME. Flow cytometry, T-cell receptor (TCR) sequencing, and RNA-sequencing (RNA-seq) analyses showed that in the CEA-transgenic murine colon carcinoma (MC38-CEA) tumor model, Ad-CEA + N-803 combination therapy resulted in immune-mediated antitumor effects and promoted the expression of costimulatory molecules on immune subsets, OX40 and GITR, and the inhibitory molecule IDO. Treatment with Ad-CEA + N-803 + OX40 + GITR + IDOi, termed the pentatherapy regimen, resulted in the greatest inhibition of tumor growth and protection from tumor rechallenge without toxicity. Monotherapy with any of the agents had little to no antitumor activity, whereas combining two, three, or four agents had minimal antitumor effects. Immune analyses demonstrated that the pentatherapy combination induced CD4⁺ and CD8⁺ T-cell activity in the periphery and tumor, and antitumor activity associated with decreased regulatory T-cell (Treg) immunosuppression in the TME. The pentatherapy combination also inhibited tumor growth and metastatic formation in 4T1 and LL2-CEA murine tumor models. This study provides the rationale for the combination of multimodal immunotherapy agents to engage, enhance, and enable adaptive antitumor immunity.

Exploiting tumor necrosis with novel immunotherapies

Tumor necrosis prior to therapy historically correlates with aggressive tumor phenotypes. However, necrosis in response to chemotherapy leads to increased progression-free and overall survival in several cancer types. Chemotherapy with docetaxel results in inhibition of mitosis, leading to necrosis. To exploit the therapeutic potential of docetaxel, a bifunctional molecule consisting of a mAb specific for histone H1 and two molecules of IL-12 (NHS-IL-12), was engineered to deliver rIL-12 to the tumor microenvironment (TME) through specific targeting of necrotic regions in the tumor. IL-12 is a proinflammatory cytokine that increases lytic capacity of T and NK cells. Although promising preclinically, rIL-12 when delivered systemically leads to severe toxicity. We hypothesize inducing necrosis leads to immunogenic modulation that can be exploited with targeted therapies resulting in increased tumor cell killing.

Here, we show pathologist confirmed increase in tumor necrosis post-delivery of docetaxel, leading to improved retention of NHS-IL-12 in the TME. Significant anti-tumor activity is observed when combining docetaxel and NHS-IL-12, but there is elevated PD-L1 expression on tumor cells and serum TGFb levels, which correlate with poor prognosis. M7824 is a fusion protein containing a mAb against PD-L1 linked to the extracellular domain of TGFbR2, sequestering TGFb. Following the strategic addition of M7824, TGFb levels in mice receiving the triple combination had significantly reduced TGFb levels. Additionally, the greatest anti-tumor activity and increase in survival was observed in cohorts receiving docetaxel, NHS-IL-12 and M7824. Data presented herein have aided in the rationale design of a clinical trial at NCI.

EDN1-AS, A Novel Long Non-coding RNA Regulating Endothelin-1 in Human Proximal Tubule Cells

Endothelin-1 (ET-1) is a peptide hormone that functions as a vasoconstrictor in the vasculature, whereas in the collecting duct of the kidney it exerts blood pressure-lowering effects via natriuretic actions. Aberrant ET-1 signaling is associated with several pathological states including hypertension and chronic kidney disease. ET-1 expression is regulated largely through transcriptional control of the gene that encodes ET-1, EDN1. Here we report a long, non-coding RNA (lncRNA) that appears to be antisense to the EDN1 gene, called EDN1-AS. Because EDN1-AS represents a potential novel mechanism to regulate ET-1 expression, we examined the regulation of EDN1-AS expression and action. A putative glucocorticoid receptor response (GR) element upstream of the predicted EDN1-AS transcription start site was identified using the ENCODE database and the UCSC genome browser. Two homozygous deletion clones of the element were generated using CRISPR/Cas9. This deletion resulted in a significant increase in the expression of EDN1-AS, which was associated with increased secretion of ET-1 peptide from HK-2 cells (two-fold increase in KO cells vs. CNTL, n = 7, P < 0.05). Phenotypic characterization of these CRISPR clones revealed a difference in cell growth rates. Using a standard growth assay, we determined that the KO1 clone exhibited a three-fold increase in growth over 8 days compared to control cells (n = 4, P < 0.01) and the KO2 clone exhibited a two-fold increase (n = 4, P < 0.01). These results support a role for EDN1-AS as a novel regulatory mechanism of ET-1 expression and cellular proliferation.

Female C57BL/6J mice lacking the circadian clock protein PER1 are protected from nondipping hypertension

The circadian clock is integral to the maintenance of daily rhythms of many physiological outputs, including blood pressure. Our laboratory has previously demonstrated the importance of the clock protein period 1 (PER1) in blood pressure regulation in male mice. Briefly, a high-salt diet (HS; 4% NaCl) plus injection with the long-acting mineralocorticoid deoxycorticosterone pivalate (DOCP) resulted in nondipping hypertension [<10% difference between night and day blood pressure (BP) in Per1-knockout (KO) mice but not in wild-type (WT) mice]. To date, there have been no studies that have examined the effect of a core circadian gene KO on BP rhythms in female mice. The goal of the present study was to determine whether female Per1-KO mice develop nondipping hypertension in response to HS/DOCP treatment. For the first time, we demonstrate that loss of the circadian clock protein PER1 in female mice does not significantly change mean arterial pressure (MAP) or the BP rhythm relative to female C57BL/6 WT control mice. Both WT and Per1-KO female mice experienced a significant increase in MAP in response to HS/DOCP. Importantly, however, both genotypes maintained a >10% dip in BP on HS/DOCP. This effect is distinct from the nondipping hypertension seen in male Per1-KO mice, demonstrating that the female sex appears to be protective against PER1-mediated nondipping hypertension in response to HS/DOCP. Together, these data suggest that PER1 acts in a sex-dependent manner in the regulation of cardiovascular rhythms.

Renal Na-handling defect associated with PER1-dependent nondipping hypertension in male mice

Many physiological functions have a circadian rhythm, including blood pressure (BP). BP is highest during the active phase, whereas during the rest period, BP dips 10-20%. Patients that do not experience this dip at night are termed "nondippers." Nondipping hypertension is associated with increased risk of cardiovascular disease. The mechanisms underlying nondipping hypertension are not understood. Without the circadian clock gene Per1, C57BL/6J mice develop nondipping hypertension on a high-salt diet plus mineralocorticoid treatment (HS/DOCP). Our laboratory has shown that PER1 regulates expression of several genes related to sodium (Na) transport in the kidney, including epithelial Na channel (ENaC) and Na chloride cotransporter (NCC). Urinary Na excretion also demonstrates a circadian pattern with a peak during active periods. We hypothesized that PER1 contributes to circadian regulation of BP via a renal Na-handling-dependent mechanism. Na-handling genes from the distal nephron were inappropriately regulated in KO mice on HS/DOCP. Additionally, the night/day ratio of Na urinary excretion by Per1 KO mice is decreased compared with WT (4 × vs. 7×, P < 0.001, n = 6 per group). Distal nephron-specific Per1 KO mice also show an inappropriate increase in expression of Na transporter genes αENaC and NCC. These results support the hypothesis that PER1 mediates control of circadian BP rhythms via the regulation of distal nephron Na transport genes. These findings have implications for the understanding of the etiology of nondipping hypertension and the subsequent development of novel therapies for this dangerous pathophysiological condition.

Desoxycorticosterone pivalate-salt treatment leads to non-dipping hypertension in Per1 knockout mice

AIM

Increasing evidence demonstrates that circadian clock proteins are important regulators of physiological functions including blood pressure. An established risk factor for developing cardiovascular disease is the absence of a blood pressure dip during the inactive period. The goal of the present study was to determine the effects of a high salt diet plus mineralocorticoid on PER1-mediated blood pressure regulation in a salt-resistant, normotensive mouse model, C57BL/6J.

METHODS

Blood pressure was measured using radiotelemetry. After control diet, wild-type (WT) and Per1 (KO) knockout mice were given a high salt diet (4% NaCl) and the long-acting mineralocorticoid deoxycorticosterone pivalate. Blood pressure and activity rhythms were analysed to evaluate changes over time.

RESULTS

Blood pressure in WT mice was not affected by a high salt diet plus mineralocorticoid. In contrast, Per1 KO mice exhibited significantly increased mean arterial pressure (MAP) in response to a high salt diet plus mineralocorticoid. The inactive/active phase ratio of MAP in WT mice was unchanged by high salt plus mineralocorticoid treatment. Importantly, this treatment caused Per1 KO mice to lose the expected decrease or 'dip' in blood pressure during the inactive compared to the active phase.

CONCLUSION

Loss of PER1 increased sensitivity to the high salt plus mineralocorticoid treatment. It also resulted in a non-dipper phenotype in this model of salt-sensitive hypertension and provides a unique model of non-dipping. Together, these data support an important role for the circadian clock protein PER1 in the modulation of blood pressure in a high salt/mineralocorticoid model of hypertension.

Abstract 130: Modulation of Salt and Mineralocorticoid Sensitivity of Blood Pressure by the Circadian Clock Protein Per1

The circadian clock is important for maintaining rhythms in physiological functions including blood pressure (BP). Circadian disruption leads to increased disease risk. The clock has also been implicated in the maintenance of a normal dip in BP at night. In humans, non-dipping (night/day difference in BP<10%) is associated with an increased risk of cardiovascular and kidney disease. Dipping status can also be affected by salt intake and by hormones such as the mineralocorticoid aldosterone. The goal of this study was to determine the effects of a high salt (HS, 4% NaCl) diet plus mineralocorticoid (deoxycorticosterone pivalate (DOCP)) on BP regulation by the circadian clock protein Per1 in C57BL/6J mice. BP was monitored in conscious, unrestrained male mice by radiotelemetry and values are reported as mean arterial pressure (MAP) ± SEM. Under control conditions, MAP in male WT mice was 112.5 ± 1.08 mmHg during the night when mice are active and decreased to 102.1 ± 1.7 mmHg during the day, a “dip” in MAP of 9.2 ± 1.3%. Similarly, Per1 KO mice dip 14 ± 1.4%, with night time MAP of 119.8 ± .9 mmHg which decreased to 103 ± 1.4 mmHg during the day. On HS/DOCP, WT mice MAP decreased from 114.5 ± 1.1 mmHg to 101.5 ± 1.92 mmHg (night indicated by shaded bars in figure). This 11.4 ± 1.9% dip in WT mice was not significantly different from what was observed under control conditions. In contrast, Per1 KO mice display a significantly attenuated dip of 5.7 ± 1.4% with night time MAP of 125.3 ± 1.5 mmHg dropping to 118.1 ± 1 mmHg during the inactive day period (p<0.05). Thus, HS/DOCP treatment in Per1 KO mice leads to non-dipping hypertension. This is the first report of this phenotype in a single clock gene KO.

The Circadian Clock in the Regulation of Renal Rhythms

Since the kidney is integral to maintenance of fluid and ion homeostasis, and therefore blood pressure regulation, its proper function is paramount. Circadian fluctuations in blood pressure, renal blood flow, glomerular filtration rate, and sodium and water excretion have been documented for decades, if not longer. Recent studies on the role of circadian clock proteins in the regulation of a variety of renal transport genes suggest that the molecular clock in the kidney controls circadian fluctuations in renal function. The circadian clock appears to be a critical regulator of renal function with important implications for the treatment of renal pathologies, which include chronic kidney disease and hypertension. The development, regulation, and mechanism of the kidney clock are reviewed here.

Transcriptional regulation of NHE3 and SGLT1 by the circadian clock protein Per1 in proximal tubule cells

We have previously demonstrated that the circadian clock protein period (Per)1 coordinately regulates multiple genes involved in Na(+) reabsorption in renal collecting duct cells. Consistent with these results, Per1 knockout mice exhibit dramatically lower blood pressure than wild-type mice. The proximal tubule is responsible for a majority of Na(+) reabsorption. Previous work has demonstrated that expression of Na(+)/H(+) exchanger 3 (NHE3) oscillates with a circadian pattern and Na(+)-glucose cotransporter (SGLT)1 has been demonstrated to be a circadian target in the colon, but whether these target genes are regulated by Per1 has not been investigated in the kidney. The goal of the present study was to determine if Per1 regulates the expression of NHE3, SGLT1, and SGLT2 in the kidney. Pharmacological blockade of nuclear Per1 entry resulted in decreased mRNA expression of SGLT1 and NHE3 but not SGLT2 in the renal cortex of mice. Per1 small interfering RNA and pharmacological blockade of Per1 nuclear entry in human proximal tubule HK-2 cells yielded the same results. Examination of heterogeneous nuclear RNA suggested that the effects of Per1 on NHE3 and SGLT1 expression occurred at the level of transcription. Per1 and the circadian protein CLOCK were detected at promoters of NHE3 and SGLT1. Importantly, both membrane and intracellular protein levels of NHE3 and SGLT1 were decreased after blockade of nuclear Per1 entry. This effect was associated with reduced activity of Na(+)-K(+)-ATPase. These data demonstrate a role for Per1 in the transcriptional regulation of NHE3 and SGLT1 in the kidney.