Expanding access to early phase trials: the CATCH-UP.2020 experience.

BACKGROUND: Disparities in cancer outcomes persist for underserved populations; one important aspect of this is limited access to promising early phase clinical trials. To address this, the National Cancer Institute-funded Create Access to Targeted Cancer Therapy for Underserved Populations (CATCH-UP.2020) was created. We report the tools developed and accrual metrics of the initial year of CATCH-UP.2020 with a focus on racial, ethnic, geographic, and socioeconomically underserved populations. METHODS: CATCH-UP.2020 is a P30 supplement awarded to 8 National Cancer Institute-designated cancer centers with existing resources to rapidly open and accrue to Experimental Therapeutics Clinical Trials Network (ETCTN) trials with emphasis on engaging patients from underserved populations. Sites used patient-based, community-based, investigator-based, and program-based tools to meet specific program goals. RESULTS: From September 2020 to August 2021, CATCH-UP.2020 sites opened 45 ETCTN trials. Weighted average trial activation time for the 7 sites reporting this was 107 days. In the initial year, sites enrolled 145 patients in CATCH-UP.2020 with 68 (46.9%) representing racial, ethnic, rural, and socioeconomically underserved populations using the broader definition of underserved encompassed in the grant charge. During the initial year of CATCH-UP.2020, a time impacted by the COVID-19 pandemic, 15.8% (66 of 417) and 21.4% (31 of 145) of patients enrolled to ETCTN trials at network and at CATCH-UP sites, respectively, were from racial and ethnic minority groups, a more limited definition of underserved for which comparable data are available. CONCLUSION: Targeted funding accelerated activation and accrual of early phase trials and expanded access to this therapeutic option for underserved populations.

VISTA Re-programs Macrophage Biology Through the Combined Regulation of Tolerance and Anti-inflammatory Pathways.

We present the novel finding that V-domain Ig suppressor of T cell activation (VISTA) negatively regulates innate inflammation through the transcriptional and epigenetic re-programming of macrophages. Representative of VISTA re-programming is the ability of VISTA agonistic antibodies to augment LPS tolerance and reduce septic shock lethality in mice. This anti-inflammatory effect of anti-VISTA was mimicked in vitro demonstrating that anti-VISTA treatment caused a significant reduction in LPS-induced IL-12p40, IL-6, CXCL2, and TNF; all hallmark pro-inflammatory mediators of endotoxin shock. Even under conditions that typically "break" LPS tolerance, VISTA agonists sustained a macrophage anti-inflammatory profile. Analysis of the proteomic and transcriptional changes imposed by anti-VISTA show that macrophage re-programming was mediated by a composite profile of mediators involved in both macrophage tolerance induction (IRG1, miR221, A20, IL-10) as well as transcription factors central to driving an anti-inflammatory profile (e.g., IRF5, IRF8, NFKB1). These findings underscore a novel and new activity of VISTA as a negative checkpoint regulator that induces both tolerance and anti-inflammatory programs in macrophages and controls the magnitude of innate inflammation in vivo.

VISTA: A Target to Manage the Innate Cytokine Storm.

In recent years, the success of immunotherapy targeting immunoregulatory receptors (immune checkpoints) in cancer have generated enthusiastic support to target these receptors in a wide range of other immune related diseases. While the overwhelming focus has been on blockade of these inhibitory pathways to augment immunity, agonistic triggering via these receptors offers the promise of dampening pathogenic inflammatory responses. V-domain Ig suppressor of T cell activation (VISTA) has emerged as an immunoregulatory receptor with constitutive expression on both the T cell and myeloid compartments, and whose agonistic targeting has proven a unique avenue relative to other checkpoint pathways to suppress pathologies mediated by the innate arm of the immune system. VISTA agonistic targeting profoundly changes the phenotype of human monocytes towards an anti-inflammatory cell state, as highlighted by striking suppression of the canonical markers CD14 and Fcγr3a (CD16), and the almost complete suppression of both the interferon I (IFN-I) and antigen presentation pathways. The insights from these very recent studies highlight the impact of VISTA agonistic targeting of myeloid cells, and its potential therapeutic implications in the settings of hyperinflammatory responses such as cytokine storms, driven by dysregulated immune responses to viral infections (with a focus on COVID-19) and autoimmune diseases. Collectively, these findings suggest that the VISTA pathway plays a conserved, non-redundant role in myeloid cell function.

Defining the Signature of VISTA on Myeloid Cell Chemokine Responsiveness.

The role of negative checkpoint regulators (NCRs) in human health and disease cannot be overstated. V-domain Ig-containing Suppressor of T-cell Activation (VISTA) is an Ig superfamily protein predominantly expressed within the hematopoietic compartment and has been studied for its role in the negative regulation of T cell responses. The findings presented in this study show that, unlike all other NCRs, VISTA deficiency dramatically impacts on macrophage cytokine and chemokine production, as well as the chemotactic response of VISTA-deficient macrophages. A select group of inflammatory chemokines, including CCL2, CCL3, CCL4, and CCL5, was strikingly elevated in culture supernatants from VISTA KO macrophages. VISTA deficiency also altered chemokine receptor recycling and profoundly disrupted myeloid chemotaxis. The impact of VISTA deficiency on chemotaxis in vivo was apparent with the reduced ability of both KO macrophages and MDSCs to migrate to the tumor microenvironment. This is the first demonstration of an NCR impacting on myeloid mediator production and chemotaxis, and will guide the use of anti-VISTA therapeutics to manipulate the chemotaxis of inflammatory macrophages or immunosuppressive MDSCs in inflammatory diseases and cancer.

Hypoxia-Induced VISTA Promotes the Suppressive Function of Myeloid-Derived Suppressor Cells in the Tumor Microenvironment.

Tumor hypoxia is a negative prognostic factor that is implicated in oncogenic signal activation, immune escape, and resistance to treatment. Identifying the mechanistic role of hypoxia in immune escape and resistance to immune-checkpoint inhibitors may aid the identification of therapeutic targets. We and others have shown that V-domain Ig suppressor of T-cell activation (VISTA), a negative checkpoint regulator in the B7 family, is highly expressed in the tumor microenvironment in tumor models and primary human cancers. In this study, we show that VISTA and HIF1α activity are correlated in a cohort of colorectal cancer patients. High VISTA expression was associated with worse overall survival. We used the CT26 colon cancer model to investigate the regulation of VISTA by hypoxia. Compared with less hypoxic tumor regions or draining lymph nodes, regions of profound hypoxia in the tumor microenvironment were associated with increased VISTA expression on tumor-infiltrating myeloid-derived suppressor cells (MDSC). Using chromatin immunoprecipitation and genetic silencing, we show that hypoxia-inducible factor (HIF)-1α binding to a conserved hypoxia response element in the VISTA promoter upregulated VISTA on myeloid cells. Further, antibody targeting or genetic ablation of VISTA under hypoxia relieved MDSC-mediated T-cell suppression, revealing VISTA as a mediator of MDSC function. Collectively, these data suggest that targeting VISTA may mitigate the deleterious effects of hypoxia on antitumor immunity.

Metastatic uveal melanoma showing durable response to anti-CTLA-4 and anti-PD-1 combination therapy after experiencing progression on anti-PD-1 therapy alone.

BACKGROUND: Uveal melanoma accounts for 85% of the ocular melanomas and has an increased risk of hematogenous spread, most commonly to the liver. After curative intent therapy like surgery and radiation, fifty percent of patients present with distant metastasis. Metastatic uveal melanoma (MUM) does not harbor typically targetable mutations, e.g., BRAF as in cutaneous melanoma. As a result, there is no proven therapy for MUM. Various chemotherapy and immunotherapy regimens have been tried and only partial response (PR) is the best that has been achieved in most of the cases. Here, we present a case of MUM treated with combination immune checkpoint therapy (ipilimumab and nivolumab) following the progression with single-agent nivolumab and demonstrating a durable response without recurrence more than 22 months from the last treatment. CASE PRESENTATION: A 72-year-old Caucasian man presented with ciliary body melanoma of the left eye and underwent curative-intent enucleation but six months later developed diffuse hepatic metastases. He initially was treated with nivolumab 3 mg/kg every two weeks for four cycles but restaging scan showed a significant progression of the disease with increasing LDH. With the FDA approval for the combination of nivolumab 1mg/kg with Ipilimumab 3 mg/kg every three weeks for metastatic melanoma, this combination was given for four cycles with continuous rise in LDH to 993 unit/L (110-220 unit/L) until finishing cycle four of the treatment. Three weeks later, maintainence nivolumab 3mg/kg was initiated but two weeks later, he developed grade 4 liver toxicity with ALT 1565 unit/L (0-55 unit/L). A presumptive diagnosis of autoimmune hepatitis was made, nivolumab was stopped and oral prednisone 1mg/kg was started with quick resolution of elevated transaminases. Restaging abdominal MRI one month after the first and last dose of maintenance nivolumab showed PR and continuous shrinkage of the metastatic lesions with no hypermetabolic activity even on PET/CT. He is 22 months' post-treatment and continues to do well without any evidence of active disease. CONCLUSION: Although, limited response has been shown to single agent immune checkpoint inhibitors and chemotherapy, our patient showed durable response with anti-CTLA-4 and anti-PD-1 combination therapy in MUM.

Immunoregulatory functions of VISTA.

Utilization of negative checkpoint regulators (NCRs) for cancer immunotherapy has garnered significant interest with the completion of clinical trials demonstrating efficacy. While the results of monotherapy treatments are compelling, there is increasing emphasis on combination treatments in an effort to increase response rates to treatment. One of the most recently discovered NCRs is VISTA (V-domain Ig-containing Suppressor of T cell Activation). In this review, we describe the functions of this molecule in the context of cancer immunotherapy. We also discuss factors that may influence the use of anti-VISTA antibody in combination therapy and how genomic analysis may assist in providing indications for treatment.

Differential ASC requirements reveal a key role for neutrophils and a noncanonical IL-1ß response to Pseudomonas aeruginosa.

The NLRC4 inflammasome is responsible for IL-1ß processing by macrophages in response to Pseudomonas aeruginosa infection. We therefore hypothesized that mice that lack ASC, an NLRC4 inflammasome adaptor protein necessary for in vitro IL-1ß production by macrophages, would be preferentially protected from a hyperinflammatory lethal challenge that is dependent on bacterial type three secretion system (T3SS) activity. We report herein that lack of ASC does not confer preferential protection in response to P. aeruginosa acute infection and that ASC(-/-) mice are capable of producing robust amounts of IL-1ß comparable with C57BL/6 mice. We now identify that neutrophils represent the ASC-independent source of IL-1ß production during the acute phases of infection both in models of acute pneumonia and peritonitis. Consequently, depletion of neutrophils in ASC(-/-) mice leads to a marked deficit in IL-1ß production in vivo. The pulmonary neutrophil IL-1ß response is predominantly dependent on caspase-1, which contrasts with data derived from ocular infection. These studies therefore identify a noncanonical mechanism of IL-1ß production by neutrophils independent of ASC and demonstrate the first physiological contribution of neutrophils as an important source of IL-1ß in response to acute P. aeruginosa infection during acute pneumonia and peritonitis.

Novel therapeutic candidates, identified by molecular modeling, induce γ-globin gene expression in vivo.

The ß-hemoglobinopathies and thalassemias are serious genetic blood disorders affecting the ß-globin chain of hemoglobin A (α(2)ß(Α)(2)). Their clinical severity can be reduced by enhancing expression of fetal hemoglobin (γ-globin), producing HbF (α(2)γ(2,)). In studies reported here, γ-globin induction by 23 novel, structurally-unrelated compounds, which had been predicted through molecular modeling and in silico screening of a 13,000 chemical library, was evaluated in vitro in erythroid progenitors cultured from normal subjects and ß-thalassemia patients, and in vivo in transgenic mice or anemic baboons. Four predicted candidates were found to have high potency, with 4- to 8-fold induction of HbF. Two of these compounds have pharmacokinetic profiles favorable for clinical application. These studies thus effectively identified high potency γ-globin inducing candidate therapeutics and validated the utility of in silico molecular modeling.

A cell stress signaling model of fetal hemoglobin induction: what doesn't kill red blood cells may make them stronger.

A major goal of hemoglobinopathy research is to develop treatments that correct the underlying molecular defects responsible for sickle cell disease and beta-thalassemia. One approach to achieving this goal is the pharmacologic induction of fetal hemoglobin (HbF). This strategy is capable of inhibiting the polymerization of sickle hemoglobin and correcting the globin chain imbalance of beta-thalassemia. Despite this promise, none of the currently available HbF-inducing agents exhibit the combination of efficacy, safety, and convenience of use that would make them applicable to most patients. The recent success of targeted drug therapies for malignant diseases suggests that this approach could be effective for developing optimal HbF-inducing agents. A first step in applying this approach is the identification of specific molecular targets. However, while >70 HbF-inducing agents have been described, neither molecular mechanisms nor target molecules have been definitively verified for any of these compounds. To help focus investigation in this area, we have reviewed known HbF-inducing agents and their proposed mechanisms of action. We find that in many cases, current models inadequately explain key experimental results. By integrating features of the erythropoietic stress model of HbF induction with data from recent intracellular signaling experiments, we have developed a new model that has the potential to explain several findings that are inconsistent with previous models and to unify most HbF-inducing agents under a common mechanism: cell stress signaling. If correct, this or related models could lead to new opportunities for development of targeted therapies for the beta-hemoglobinopathies.

Neither DNA hypomethylation nor changes in the kinetics of erythroid differentiation explain 5-azacytidine's ability to induce human fetal hemoglobin.

5-azacytidine (5-Aza) is a potent inducer of fetal hemoglobin (HbF) in people with beta-thalassemia and sickle cell disease. Two models have been proposed to explain this activity. The first is based on the drug's ability to inhibit global DNA methylation, including the fetal globin genes, resulting in their activation. The second is based on 5-Aza's cytotoxicity and observations that HbF production is enhanced during marrow recovery. We tested these models using human primary cells in an in vitro erythroid differentiation system. We found that doses of 5-Aza that produce near maximal induction of gamma-globin mRNA and HbF do not alter cell growth, differentiation kinetics, or cell cycle, but do cause a localized demethylation of the gamma promoter. However, when we reduced gamma promoter methylation to levels equivalent to those seen with 5-Aza or to the lower levels seen in primary fetal erythroid cells using DNMT1 siRNA and shRNA, we observed no induction of gamma-globin mRNA or HbF. These results suggest that 5-Aza induction of HbF is not the result of global DNA demethylation or of changes in differentiation kinetics, but involves an alternative, previously unrecognized mechanism. Other results suggest that posttranscriptional regulation plays an important role in the 5-Aza response.

Developmental- and differentiation-specific patterns of human gamma- and beta-globin promoter DNA methylation.

The mechanisms underlying the human fetal-to-adult beta-globin gene switch remain to be determined. While there is substantial experimental evidence to suggest that promoter DNA methylation is involved in this process, most data come from studies in nonhuman systems. We have evaluated human gamma- and beta-globin promoter methylation in primary human fetal liver (FL) and adult bone marrow (ABM) erythroid cells. Our results show that, in general, promoter methylation and gene expression are inversely related. However, CpGs at -162 of the gamma promoter and -126 of the beta promoter are hypomethylated in ABM and FL, respectively. We also studied gamma-globin promoter methylation during in vitro differentiation of erythroid cells. The gamma promoters are initially hypermethylated in CD34(+) cells. The upstream gamma promoter CpGs become hypomethylated during the preerythroid phase of differentiation and are then remethylated later, during erythropoiesis. The period of promoter hypomethylation correlates with transient gamma-globin gene expression and may explain the previously observed fetal hemoglobin production that occurs during early adult erythropoiesis. These results provide the first comprehensive survey of developmental changes in human gamma- and beta-globin promoter methylation and support the hypothesis that promoter methylation plays a role in human beta-globin locus gene switching.

CpG hypomethylation in a large domain encompassing the embryonic beta-like globin genes in primitive erythrocytes.

There is little evidence addressing the role of CpG methylation in transcriptional control of genes that do not contain CpG islands. This is reflected in the ongoing debate about whether CpG methylation merely suppresses retroelements or if it also plays a role in developmental and tissue-specific gene regulation. The genes of the beta-globin locus are an important model of mammalian developmental gene regulation and do not contain CpG islands. We have analyzed the methylation status of regions in the murine beta-like globin locus in uncultured primitive and definitive erythroblasts and other cultured primary and transformed cell types. A large ( approximately 20-kb) domain is hypomethylated only in primitive erythroid cells; it extends from the region just past the locus control region to before beta-major and encompasses the embryonic genes Ey, beta h1, and beta h0. Even retrotransposons in this region are hypomethylated in primitive erythroid cells. The existence of this large developmentally regulated domain of hypomethylation supports a mechanistic role for DNA methylation in developmental regulation of globin genes.

Short-chain fatty acids induce gamma-globin gene expression by displacement of a HDAC3-NCoR repressor complex.

High-level induction of fetal (gamma) globin gene expression for therapy of beta-hemoglobinopathies likely requires local chromatin modification and dissociation of repressor complexes for gamma-globin promoter activation. A novel gamma-globin-inducing short-chain fatty acid derivative (SCFAD), RB7, which was identified through computational modeling, produced a 6-fold induction in a reporter assay that detects only strong inducers of the gamma-globin gene promoter and in cultured human erythroid progenitors. To elucidate the molecular mechanisms used by high-potency SCFADs, chromatin immunoprecipitation (ChIP) assays performed at the human gamma- and beta-globin gene promoters in GM979 cells and in erythroid progenitors demonstrate that RB7 and butyrate induce dissociation of HDAC3 (but not HDAC1 or HDAC2) and its adaptor protein NCoR, specifically from the gamma-globin gene promoter. A coincident and proportional recruitment of RNA polymerase II to the gamma-globin gene promoter was observed with exposure to these gamma-globin inducers. Knockdown of HDAC3 by siRNA induced transcription of the gamma-globin gene promoter, demonstrating that displacement of HDAC3 from the gamma-globin gene promoter by the SCFAD is sufficient to induce gamma-globin gene expression. These studies demonstrate new dynamic alterations in transcriptional regulatory complexes associated with SCFAD-induced activation of the gamma-globin gene and provide a specific molecular target for potential therapeutic intervention.