Focused ultrasound-mediated blood-brain barrier opening is safe and feasible with moderately hypofractionated radiotherapy for brainstem diffuse midline glioma

BACKGROUND

Diffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic strategies have been unsuccessful and radiotherapy (RT) remains the standard-of-care. A central impediment to treatment is the blood-brain barrier (BBB), which precludes drug delivery to the central nervous system (CNS). Focused ultrasound (FUS) with microbubbles can transiently and non-invasively disrupt the BBB to enhance drug delivery. This study aimed to determine the feasibility of brainstem FUS in combination with clinical doses of RT. We hypothesized that FUS-mediated BBB-opening (BBBO) is safe and feasible with 39 Gy RT.

METHODS

To establish a safety timeline, we administered FUS to the brainstem of non-tumor bearing mice concurrent with or adjuvant to RT; our findings were validated in a syngeneic brainstem murine model of DMG receiving repeated sonication concurrent with RT. The brainstems of male B6 (Cg)-Tyrc-2J/J albino mice were intracranially injected with mouse DMG cells (PDGFB+, H3.3K27M, p53-/-). A clinical RT dose of 39 Gy in 13 fractions (39 Gy/13fx) was delivered using the Small Animal Radiation Research Platform (SARRP) or XRAD-320 irradiator. FUS was administered via a 0.5 MHz transducer, with BBBO and tumor volume monitored by magnetic resonance imaging (MRI).

RESULTS

FUS-mediated BBBO did not affect cardiorespiratory rate, motor function, or tissue integrity in non-tumor bearing mice receiving RT. Tumor-bearing mice tolerated repeated brainstem BBBO concurrent with RT. 39 Gy/13fx offered local control, though disease progression occurred 3-4 weeks post-RT.

CONCLUSION

Repeated FUS-mediated BBBO is safe and feasible concurrent with RT. In our syngeneic DMG murine model, progression occurs, serving as an ideal model for future combination testing with RT and FUS-mediated drug delivery.

Elucidation and Pharmacologic Targeting of Master Regulator Dependencies in Coexisting Diffuse Midline Glioma Subpopulations

Diffuse Midline Gliomas (DMGs) are universally fatal, primarily pediatric malignancies affecting the midline structures of the central nervous system. Despite decades of clinical trials, treatment remains limited to palliative radiation therapy. A major challenge is the coexistence of molecularly distinct malignant cell states with potentially orthogonal drug sensitivities. To address this challenge, we leveraged established network-based methodologies to elucidate Master Regulator (MR) proteins representing mechanistic, non-oncogene dependencies of seven coexisting subpopulations identified by single-cell analysis-whose enrichment in essential genes was validated by pooled CRISPR/Cas9 screens. Perturbational profiles of 372 clinically relevant drugs helped identify those able to invert the activity of subpopulation-specific MRs for follow-up in vivo validation. While individual drugs predicted to target individual subpopulations-including avapritinib, larotrectinib, and ruxolitinib-produced only modest tumor growth reduction in orthotopic models, systemic co-administration induced significant survival extension, making this approach a valuable contribution to the rational design of combination therapy.

Immune Response following FLASH and Conventional Radiation in Diffuse Midline Glioma

PURPOSE

Diffuse midline glioma (DMG) is a fatal tumor traditionally treated with radiation therapy (RT) and previously characterized as having a noninflammatory tumor immune microenvironment (TIME). FLASH is a novel RT technique using ultra-high dose rate that is associated with decreased toxicity and effective tumor control. However, the effect of FLASH and conventional (CONV) RT on the DMG TIME has not yet been explored.

METHODS AND MATERIALS

Here, we performed single-cell RNA sequencing (scRNA-seq) and flow cytometry on immune cells isolated from an orthotopic syngeneic murine model of brainstem DMG after the use of FLASH (90 Gy/sec) or CONV (2 Gy/min) dose-rate RT and compared to unirradiated tumor (SHAM).

RESULTS

At day 4 post-RT, FLASH exerted similar effects as CONV in the predominant microglial (MG) population, including the presence of two activated subtypes. However, at day 10 post-RT, we observed a significant increase in the type 1 interferon α/β receptor (IFNAR+) in MG in CONV and SHAM compared to FLASH. In the non-resident myeloid clusters of macrophages (MACs) and dendritic cells (DCs), we found increased type 1 interferon (IFN1) pathway enrichment for CONV compared to FLASH and SHAM by scRNA-seq. We observed this trend by flow cytometry at day 4 post-RT in IFNAR+ MACs and DCs, which equalized by day 10 post-RT. DMG control and murine survival were equivalent between RT dose rates.

CONCLUSIONS

Our work is the first to map CONV and FLASH immune alterations of the DMG TIME with single-cell resolution. Although DMG tumor control and survival were similar between CONV and FLASH, we found that changes in immune compartments differed over time. Importantly, although both RT modalities increased IFN1, we found that the timing of this response was cell-type and dose-rate dependent. These temporal differences, particularly in the context of tumor control, warrant further study.

Focused Ultrasound for Blood-Brain Barrier Opening and Delivery of Anti-PD1 in Diffuse Midline Gliomas

PURPOSE/OBJECTIVE(S)

Diffuse midline glioma with H3K27 mutation is a fatal pediatric brain tumor, most commonly arising in the brainstem. This tumor remains universally fatal, despite a multitude of clinical trials, with a median overall survival of only 9-12 months. While immune-checkpoint inhibitors (ICIs) have transformed the treatment landscape of multiple solid tumors, delivery past the blood brain barrier (BBB) remains challenging. Programmed cell death protein 1 (PD1) is an immune checkpoint protein expressed on the surface of activated T cells; interaction with its ligand, PDL1, is tumor-protective, dampening T cell response. Recent phase I clinical trials have shown that ICIs targeting proteins along the PD1/PDL1 axis are well tolerated in patients with DMG; however, efficacy remains low. The blood-brain barrier (BBB) poses a major challenge to the efficacious delivery of therapeutic agents with large molecular size, such as anti-PD1. We hypothesize that BBB opening (BBBO) using focused ultrasound (FUS), a form of non-ionizing acoustic radiation, can enhance delivery and efficacy of anti-PD1 for treatment of DMG.

MATERIALS/METHODS

We established a syngeneic mouse DMG model with intracranial injection of cell line 4423 (PDGFB+, H3.3K27M, p53-/-). Magnetic resonance imaging (MRI) was utilized to evaluate BBBO and tumor progression. We measured delivery of anti-PD1 after BBBO using Western Blot and 3D in vivo optical fluorescent imaging/CT (OI/CT) of Cy7 labeled anti-PD1.

RESULTS

We demonstrate that delivery of anti-PD1 can be enhanced over 3.5-fold after reversible BBBO with FUS and concurrent microbubble administration. OI/CT revealed enhanced real-time antibody distribution peritumorally. Furthermore, we demonstrate that combined treatment of FUS and anti-PD1 led to benefit in local control of tumor growth using volumetric analysis of MRI. Preliminary survival studies suggest a positive trend for overall survival.

CONCLUSION

Our results support that FUS-mediated BBBO can increase treatment efficacy of anti-PD1 in a DMG murine model, due to improved targeted delivery to the tumoral region after systemic antibody administration. We consider these findings strong rationale for further investigation of the therapeutic effects of combinatorial treatment using FUS-mediated BBBO and ICIs for the treatment of DMG.

Leptomeningeal dissemination in pediatric brain tumors

Leptomeningeal disease (LMD) in pediatric brain tumors (PBTs) is a poorly understood and categorized phenomenon. LMD incidence rates, as well as diagnosis, treatment, and screening practices, vary greatly depending on the primary tumor pathology. While LMD is encountered most frequently in medulloblastoma, reports of LMD have been described across a wide variety of PBT pathologies. LMD may be diagnosed simultaneously with the primary tumor, at time of recurrence, or as primary LMD without a primary intraparenchymal lesion. Dissemination and seeding of the cerebrospinal fluid (CSF) involves a modified invasion-metastasis cascade and is often the result of direct deposition of tumor cells into the CSF. Cells develop select environmental advantages to survive the harsh, nutrient poor and turbulent environment of the CSF and leptomeninges. Improved understanding of the molecular mechanisms that underlie LMD, along with improved diagnostic and treatment approaches, will help the prognosis of children affected by primary brain tumors.

Abstract 4304: Network-based inference identifies cell state-specific drugs targeting master regulator vulnerabilities in diffuse midline glioma

Diffuse Midline Glioma (DMG) are fatal pediatric brain tumors with no therapies. We leveraged network-based methodologies to dissect the heterogeneity of DMG tumors and to discover Master Regulator (MR) proteins representing pharmacologically accessible, mechanistic determinants of molecularly distinct cell states. We produced the first DMG regulatory network from 122 publicly available RNAseq profiles with ARACNe (Basso et al. Nat Genet 2005), and inferred sample-specific MR protein activity with VIPER (Alvarez et al. Nat Genet 2016) based on the differential expression of their targets. 7 of the top 25 most active MRs found comprise a well-characterized MR block (MRB2) (Paull et al.Cell 2021), frequently activated across aggressive tumors, and enriched in DMG patient MR signatures (Fisher’s Exact Test p=4.4 × 10−18). A CRISPR/Cas9 KO screen across 3 DMG patient cell lines identified a set of 73/77 essential genes that were enriched in the MR signature of 80% of patient samples (GSEA p=0.000034). FOXM1 emerged as an essential MR, significantly activated across virtually all patients.

We then generated RNAseq profiles following perturbation with ~300 oncology drugs in 2 DMG cell lines most representative of patient MR signatures, and used this to identify drugs that invert patient MR activity profiles using the NYS/CA Dept. of Health approved OncoTreat algorithm (Alvarez et al. Nat Genet 2018). OncoTreat predicted sensitivity to HDAC, MEK, CDK, PI3K, and proteosome inhibitors in subsets of patients, overlapping with published DMG drug screens. Importantly, 80% of OncoTreat-predicted drugs (p<10−5) from 3 DMG patient tumor biopsies showed in vitro sensitivity in cultured tumor cells from the respective patients, with overall 68% accuracy among 223 drugs evaluated by both OncoTreat and in vitro (Fisher’s Exact Test p=0.0449).

Further analysis of DMG intra-tumor heterogeneity via protein activity inference across DMG single cells from 6 published scRNAseq profiles identified 6 tumor clusters with unique MR signatures co-existing in virtually all patients representing distinct cellular states (2 astrocyte-, 1 oligodendrocyte-, and 3 oligodendrocyte precursor cell-like states). Targetable MRs and OncoTreat-predicted drugs were distinct between these states. Bulk RNAseq analysis recapitulated predictions seen in the more prevalent OPC-like states, but failed to capture MR and drug predictions for the AC-like states (e.g. JAK1/Ruxolitinib and STAT3/Napabucasin). We are currently validating cell state-specific drug predictions in vivo at single-cell resolution in subcutaneous patient-derived xenograft and orthotopic syngeneic DMG models that we have shown recapitulate patient tumor heterogeneity, including with focused ultrasound-mediated drug delivery. This provides a platform to nominate much-needed novel drugs and drug combinations to treat DMG.

Citation Format: Ester Calvo Fernandez, Junqiang Wang, Xu Zhang, Hong-Jian Wei, Hanna E. Minns, Aaron T. Griffin, Lukas Vlahos, Timothy J. Martins, Pamela S. Becker, John Crawford, Robyn D. Gartrell, Luca Szalontay, Stergios Zacharoulis, Zhiguo Zhang, Robert Wechsler-Reya, Cheng-Chia Wu, Andrea Califano, Jovana Pavisic. Network-based inference identifies cell state-specific drugs targeting master regulator vulnerabilities in diffuse midline glioma. [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 4304.

TMIC-68. EVALUATING FLASH AND CONVENTIONAL DOSE-RATE RADIATION AND IMMUNE RESPONSE WITH SINGLE-CELL SEQUENCING IN DIFFUSE MIDLINE GLIOMA (DMG)

Diffuse Midline Glioma – H3K27M mutant (DMG), is a fatal and inoperable pediatric brain tumor with limited treatment options as radiation provides only temporary reprieve, leaving the median survival between 9-15 months. Conventional dose-rate radiation (2Gray/minute, CONV) has been shown in other cancers to recruit an immune component, however, this has not been studied in DMG. Ultra-high dose-rate radiation given at 90 Gray/second (FLASH), is a novel technique associated with decreased toxicity and effective tumor control. Using a syngeneic model of brainstem DMG, we performed single-cell RNA sequencing on CD45+ immune cells isolated from tumors irradiated with 15Gray using FLASH or CONV, and compared to unirradiated tumor and normal brainstem. Isolation of 33,308 immune cells revealed 17 unique clusters, most abundant of which was microglia (73.8%), present in four distinct subtypes representing a spectrum from homeostatic to activated. In the most activated microglia, both FLASH and CONV showed an enrichment in type 1 interferon (IFN1) pathway scores compared to untreated tumors (p< 0.001 and p< 0.001, respectively). The most differential response was found in macrophages (MAC) and dendritic cells (DC) with a robust enrichment of IFN1 pathway scores for CONV compared to FLASH (p< 0.001, MAC and p< 0.001 DC). FLASH showed an increase in anti-inflammatory MAC markers such as Mrc1, Cd163, and Maf and an enrichment of myeloid-derived suppressor cell (MDSC) signature in monocytes, not seen in CONV (p< 0.001). Finally, we correlated our data with publicly available single-cell data taken from the cerebrospinal fluid of DMG patients treated with anti-GD2 CAR T Cell therapy and found similar inflammatory markers characteristic of our unirradiated murine tumors. In summary, our work is the first to study immune alterations comparing different dose-rates of radiation with single-cell resolution in DMG, highlighting the potential for combining radiation and immunotherapy in these tumors.

Abstract 486: A systems biology approach to defining tumor heterogeneity, prognostic and targetable master regulator protein signatures from bulk and single cell RNA-seq in diffuse midline glioma (DMG)

Despite major advances in molecular profiling and numerous clinical trials, diffuse midline glioma (DMG) remains a fatal disease with median survival of only ~9 months and no identified effective drugs. To address this challenge, we leveraged network-based methodologies to dissect the heterogeneity of DMG tumors and to discover Master Regulator (MR) proteins representing pharmacologically accessible, mechanistic determinants of molecularly distinct DMG cell states. The study has produced the first DMG-specific regulatory network, reverse-engineered from 122 publicly available pediatric DMG RNA-seq profiles with ARACNe (Basso et al. Nat Genet 2005). Using this network, we measured protein activity for each sample via VIPER (Alvarez et al., Nat Genet 2016). Activity-based clustering identified 2 clusters, characterized by significant overall survival difference (>1 year, p-val=0.02 by χ2 analysis). Protein activity signatures were not significantly associated with tumor location and Histone3 mutation status. The most aberrantly activated MR proteins across all DMG patients (i.e., TOP2A, CENPF, BUB1B, FOXM1, GTSE1, MKI67, and E2F8), relative to normal caudate tissue from GTEx, were highly enriched in cell cycle regulation members, with samples in the worst outcome cluster showing significantly higher activity. Pharmacologically accessible MRs found to be significantly activated in subsets of patients (p-val<10E-5) include TOP2A, CHEK1, CDK2, and EZH2.

To dissect DMG intra-tumor heterogeneity, we measured protein activity from published single-cell RNA-seq profiles of 6 DMG patients, using single-cell based regulatory networks. Activity-based analysis of tumor cells identified 8 clusters representing distinct differentiation and proliferation stages—i.e. astrocyte-like, oligodendrocyte-like, and multiple oligodendrocyte precursor cell (OPC)-like subpopulations. Consistent with bulk-based findings, these included an OPC-like-cycling population presenting highly aberrant activity of proliferative MRs (i.e. TOP2A, CENPF, FOXM1, E2F8, ZWINT, and CCNA2), suggesting this as a key DMG regulatory module (Tumor Checkpoint). We are working to define targetable MRs in these subpopulations, and generating RNA-seq profiles of SU-DIPG-VI and SF8628, two DMG cell lines showing protein activity similarity to >95% of patient samples by enrichment analysis (p-val < 10E-5), following perturbation with ~400 oncology drugs. This will allow us to identify drugs capable of inducing tumor demise by inverting the activity of the MRs of each tumor subpopulation, using the NY Dept. of Health approved OncoTreat algorithm (Alvarez et al., Nat Genet 2018). We are currently finalizing and validating both MR and drug predictions to nominate novel, much-needed therapeutic strategies.

Citation Format: Ester Calvo Fernández, Junqiang Wang, Aaron T. Griffin, Luca Szalontay, Stergios Zacharoulis, Jovana Pavisic, Andrea Califano. A systems biology approach to defining tumor heterogeneity, prognostic and targetable master regulator protein signatures from bulk and single cell RNA-seq in diffuse midline glioma (DMG) [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 486.

EPID-07. Outcome disparities in children, adolescents and young adults with medulloblastoma: A population-based analysis

Medulloblastoma (MB) is the most common high-grade primary pediatric brain tumor. Recent registry-based studies in children with central nervous system (CNS) tumors have demonstrated that survival outcomes differ by race/ethnicity in multivariable analyses, with Hispanic patients having highest hazard of death overall. To investigate this finding in MB patients, we examined survival in children (0-14 years) and adolescent/young adults (15-39 years) with MB from 2007-2016 in the 2018 Surveillance Epidemiology and End Results Program database, using Kaplan Meier analysis, log-rank test and Cox proportional hazard ratios (HR) with 95% confidence intervals (CI). Race and ethnicity were categorized according to the U.S. Census, with Hispanic ethnicity (yes/no) analyzed separately from race (Black, White, Asian, Other). Among 1612 patients, 81% were White, 9% were Black, 8% were Asian or Pacific Islander, and 2% were from “other” or unknown racial groups. 28% of the cohort was of Hispanic ethnicity. Univariate analysis found that Black patients had a significantly higher hazard of death than White patients (HR=1.55, CI: 1.16 – 2.08, p=0.003). In contrast, Hispanic ethnicity was not significantly associated with outcome (HR=0.98, CI: 0.79-1.21, p=0.8). Medicaid or no insurance (vs. private) were each significantly associated with higher risk of death; Medicaid (HR =1.23, CI = 1.01 - 1.51, p=0.041); Uninsured (HR=2.07, CI=1.41-3.02, p=<0.001). Of the treatment modalities analyzed, patients who received neither chemotherapy nor radiation experienced higher hazard of death than patients who received both treatments (HR=3.63, CI 2.78-4.76, p=<0.001). Consistent with observations in other cancers, racial disparities are observed in patients with MB, with Black race conferring increased risk of death. Public insurance was also significantly associated with death, as was not receiving combined-modality therapy. Further work is needed to understand the multilevel factors impacting diagnosis, treatment and outcome among children and AYAs with MB and prospective studies are warranted.

DDEL-07. A Phase I study examining the feasibility of intermittent convection-enhanced delivery (CED) of MTX110 for the treatment of children with newly diagnosed diffuse midline gliomas (DMGs)

Histone deacetylase inhibitors have been found preclinically to be among the most active agents against DMGs, however, they are clinically ineffective with systemic delivery due to blood brain barrier limitations and toxicity. Using a repurposed device (implantable subcutaneous pump connected with a catheter directly implanted into the pons/thalamus) we are performing a phase I, standard 3 + 3 dose escalation study to investigate the safety and feasibility of repeated infusions of MTX110 (Midatech Pharma), a water-soluble formulation of panobinostat, via CED. Eligible patents are between 3 and 18 years of age with newly diagnosed DMG following radiation therapy, without hemorrhage or cyst in the tumor, and having intact organ function. Following tumor biopsy and device implantation, patients receive two 48-hour-infusion pulses 7 days apart of MTX110 (30, 60, or 90 mM). The infusion pump is prefilled with MTX110 (and gadolinium for co-infusion to serve as a surrogate for drug distribution) and administered using the wireless N’Vision clinical programmer at a rate of 0.2 mL/hr. Seven patients (30 mM group, n=3 and 60 mM group, n=4) have been treated with the MTX110 infusate. All but one patient had adequate tumor coverage as measured by co-infused gadolinium on MRI. One patient suffered a severe adverse event related to the infusion and tumor anatomy. Four patients had Grade 2 transient neurological deficits related to biopsy (n=1) and the infusion (n=3). In a follow up period of 12-22 months from diagnosis, progression free survival ranges from 8 to 20 months. With one objective response, 3 patients remain alive (2 without progression, both at 12 months, and 1 with progressive disease, at 22 months post diagnosis). Three patients are expected to be treated at 90 mM level. Using MTX110, we demonstrated the safety and feasibility of repeated drug infusion by CED in DMG patients.

MODL-24. Focused ultrasound-mediated blood-brain barrier opening and panobinostat in a thalamic syngeneic murine DMG model is feasible and safe

Diffuse Midline Glioma with H3K27M mutation (DMG) is an aggressive unresectable central nervous system tumor of the brainstem, midline thalamus, or spine. Prognosis is poor and systemic agents have been ineffective partially due to limited permeability of the blood brain barrier (BBB). Non-invasive low intensity focused ultrasound (FUS) can be used for BBB opening (BBBO). Our preclinical studies showed safety and feasibility of targeting and BBBO in the brainstem; however, to our knowledge, FUS-guided BBBO for thalamic DMG has yet to be reported. RNA-seq was performed on mouse syngeneic DMG cells 4423 (PDGFB+, H3.3K27M, p53−/−) and results recapitulated molecular programs seen in human tumors. 4423 cells were injected into the thalamus of male B6 (Cg)-Tyrc-2J/J mice at 1.6mm lateral and 1.8mm posterior to the bregma at a depth of 3.2mm. MRI at 14-21 days post injection confirmed thalamic tumor growth. Histological analysis with Hematoxylin and Eosin stain was consistent with thalamic DMG. Tumor implantation rate was 85% and median survival was 38 days post injection. To test safety and feasibility of BBBO for thalamic tumors, a 1.5 MHz FUS transducer was used with concurrent microbubble injection. BBBO assessed by contrast-enhanced MRI. FUS achieved BBBO targeting the thalamic tumor without increased morbidity or mortality and BBB closure was observed on day 3 post-sonication. Next we tested the tolerance of drug delivery with panobinostat post-FUS at a dose of 20mg/kg weekly. The results are preliminary at this time; however, animals tolerated the combination therapy without morbidity or mortality. Preclinical models are crucial to improve the development of new therapeutic strategies. Establishing this syngeneic thalamic DMG murine model provides the opportunity to test FUS as a non-invasive drug delivery technology for thalamic DMG compared to brainstem DMG, and to re-visit therapeutic agents previously considered ineffective due to limited penetration of the BBB.

MODL-25. Radiation and focused ultrasound–mediated blood–brain barrier opening for DMG: safety and feasibility of combinatorial therapy

Diffuse midline glioma (DMG) is a pediatric tumor with dismal prognosis. Systemic therapeutic strategies have been unsuccessful to date and radiotherapy (RT) remains the standard of care. A central impediment to systemic therapy is the blood-brain barrier (BBB), which precludes drug delivery to the tumor site. Focused ultrasound (FUS) with intravenous microbubbles can transiently and non-invasively circumvent the BBB to enhance drug delivery. Nevertheless, it remains unclear whether FUS is safe at the brainstem in combination with clinical doses of RT. In this study, we hypothesized that FUS-mediated BBB-opening (BBBO) is safe and feasible with 39 Gy RT. To establish a safety timeline, we administered FUS to the brainstem of nontumor bearing mice concurrent with or adjuvant to radiation; then, we validated our findings in a syngeneic orthotopic xenograft DMG model which received repeated sonication concurrent with RT. Male B6 (Cg)-Tyrc-2J/J albino mice received intracranial injection of 4423 mouse DMG cells (PDGFB+, H3.3K27M, p53−/−) at a location posterior and lateral to the lambda. A clinical RT dose of 39 Gy in 13 fractions was delivered to the brainstem with the Small Animal Radiation Research Platform (SARRP) or the XRAD-320 irradiator. FUS was administered with a 0.5 MHz transducer, and both BBBO and tumor volume were monitored with MRI. FUS-mediated BBBO in nontumor bearing mice receiving RT did not affect cardiorespiratory rate, motor function, and tissue integrity. Moreover, tumor bearing mice tolerated repeated brainstem BBBO concurrent with RT. 39 Gy over 13 fractions offered local control, although disease progression occurred in all animals approximately 3-4 weeks post-RT. Ultimately, repeated FUS-mediated BBB opening concurrent with RT is safe and feasible. In our brainstem DMG model, relapse occurs, making it ideal for future tests of combinatorial RT and FUS-mediated drug delivery.

PATH-16. Noninvasive diagnosis of gliomas through CSF cfDNA sequencing in pediatric and adolescent and young adult (AYA) patients

PURPOSE: A subset of pediatric, adolescent and young adult (AYA) gliomas are located in the brainstem, eloquent locations, or present with diffuse/leptomeningeal disease, and are associated with high risk and low yield of biopsy. At the same time, accurate molecular diagnosis is necessary to direct optimal therapy. In such cases, analysis of cell free DNA (cfDNA) form cerebral spinal fluid (CSF) may represent a diagnostic alternative to biopsy. METHODS: We investigated the utility of CSF cfDNA sequencing through a stepwise approach, using clinically validated, targeted molecular assays. Testing was performed using a broad hybrid capture next generation sequencing assay (MSK-IMPACT) and subsequent targeted digital droplet PCR in a subset of cases. RESULTS: We analyzed 17 CSF samples from 17 pediatric (n=6) and AYA (n=11) glioma patients with primary or recurrent disease. Thirteen had tumors located within the brainstem, and four had leptomeningeal involvement. Somatic alterations were detected in 12/17 samples (71%). In 3/4 patients with leptomeningeal involvement, cfDNA testing revealed a BRAF fusion consistent with the diagnosis of diffuse leptomeningeal glioneuronal tumor (DLGNT). Among the 13 patients with brainstem involvement, four had somatic H3 K27M mutations, three had IDH mutations, and one had TP53 and ATRX mutations; five patients had no detectable mutations. CONCLUSION: In our analysis, we found that established glioma hotspot mutations were able to be detected within the CSF. We propose that in patients for whom tissue biopsy is high risk, not feasible, or tissue was nondiagnostic, CSF cfDNA sequencing has a substantial diagnostic yield and should be considered as a valuable novel diagnostic tool. Ongoing research is aiming to further increase the sensitivity of cfDNA testing, especially in patients with very low levels of CSF cfDNA.

DIPG-45. Radiation induces a robust interferon response in Diffuse Midline Glioma (DMG), improving the potential for combination immunotherapy

Diffuse Midline Glioma (DMG), H3K27M altered, confers a dismal survival of 9-15 months and has a non-inflammatory tumor immune microenvironment (TIME). Radiation therapy (RT) is the mainstay treatment for DMG and has been shown in other cancers to recruit an immune component. However, the effect of RT on the DMG TIME has not been explored. In a syngeneic murine model of pontine DMG (PDGFB+, H3.3K27M, p53−/−), mice were treated with single fraction 15Gy RT or sham control, four mice per group. We performed single cell sequencing after CD45 isolation to evaluate the TIME 4 days post RT and compare to untreated tumor (sham control). Unsupervised clustering of 14,848 CD45+ cells revealed 16 immune cell subsets, most abundantly microglia at 75% of cells, with four subtypes representing a spectrum of homeostatic to activated. Microglia from RT are more concentrated in the activated subtypes with an upregulation of interferon response (i.e. Isg15, Ifit3) compared to untreated tumor with an increase in several interferon pathways using REACTOME. Consistent with RT response, RT treated tumors have increase in cell cycle regulatory genes such as Cdkn1a, across all clusters. In non-resident myeloid cells, compared to untreated tumor, RT is associated with a robust upregulation of interferon response genes in both macrophages (Isg15 Fold Change (FC) 2.30; Ifit1 FC 1.64; Ifit3 FC 2.02; Cxcl10 FC 2.29) and dendritic cells (Isg15 FC 2.67; Ifit1 FC 1.72; Ifit3 FC 2.06; Cxcl10 FC 1.50). We also find differential expression of immune checkpoints in RT-treated versus untreated tumor with decreased expression of Lag3, Tim3 (Havcr2), and Csf1R and increased expression of Cd47, Sirpa and Gitr (Tnfrsf18) post RT. In summary, RT stimulates a pro-inflammatory TIME response and alters immune checkpoints in DMG, highlighting the potential for combining RT and immunotherapy in these tumors.

Next-generation sequencing of cerebrospinal fluid for clinical molecular diagnostics in pediatric, adolescent and young adult brain tumor patients

BACKGROUND

Safe sampling of central nervous system tumor tissue for diagnostic purposes may be difficult if not impossible, especially in pediatric patients, and an unmet need exists to develop less invasive diagnostic tests.

METHODS

We report our clinical experience with minimally invasive molecular diagnostics using a clinically validated assay for sequencing of cerebrospinal fluid (CSF) cell-free DNA (cfDNA). All CSF samples were collected as part of clinical care, and results reported to both clinicians and patients/families.

RESULTS

We analyzed 64 CSF samples from 45 pediatric, adolescent and young adult (AYA) patients (pediatric = 25; AYA = 20) with primary and recurrent brain tumors across 12 histopathological subtypes including high-grade glioma (n = 10), medulloblastoma (n = 10), pineoblastoma (n = 5), low-grade glioma (n = 4), diffuse leptomeningeal glioneuronal tumor (DLGNT) (n = 4), retinoblastoma (n = 4), ependymoma (n = 3), and other (n = 5). Somatic alterations were detected in 30/64 samples (46.9%) and in at least one sample per unique patient in 21/45 patients (46.6%). CSF cfDNA positivity was strongly associated with the presence of disseminated disease at the time of collection (81.5% of samples from patients with disseminated disease were positive). No association was seen between CSF cfDNA positivity and the timing of CSF collection during the patient's disease course.

CONCLUSIONS

We identified three general categories where CSF cfDNA testing provided additional relevant diagnostic, prognostic, and/or therapeutic information, impacting clinical assessment and decision making: (1) diagnosis and/or identification of actionable alterations; (2) monitor response to therapy; and (3) tracking tumor evolution. Our findings support broader implementation of clinical CSF cfDNA testing in this population to improve care.

91 Impact of ultra-fast ‘FLASH’ radiotherapy on single cell immunogenomics in diffuse intrinsic pontine glioma (DIPG)

Background

Diffuse intrinsic pontine gliomas (DIPG’s) are immunologically inert tumors with a median survival of 9–15 months. Radiation therapy (RT) is the mainstay treatment for DIPG but is associated with immunodepletion of the tumor microenvironment (TME) at high dose ranges. FLASH, or ultra-fast dose rate RT, represents a novel ablative technique that may spare TME immune responses while decreasing tumor burden. Here, we present single-cell immune profiling of DIPG tumors treated with FLASH, conventional dose rate RT (CONV) or no RT (SHAM).

Methods

Murine H3.3K27M mutant DIPG cells were stereotactically injected and tumor induction confirmed by magnetic resonance imaging (MRI) 15 days later. DIPG-bearing mice were randomly assigned to one of three treatment groups (n=4/group), FLASH, CONV or SHAM. A fourth group with no tumor (NML) was included as a negative biological control. A modified linear accelerator was used to deliver 15 Gy of electron RT to the brainstem at dose rates of 90 Gy/second and 2 Gy/minute, for the FLASH and CONV groups, respectively. Four days post-RT, mice brainstems were harvested, homogenized, stained for CD45 and tagged with a hashtag antibody specific to each group. CD45+ immune cells were isolated and sequenced using the 10X Genomics chromium single-cell 3’ platform. After processing and alignment of the reads using CellRanger with default parameters, the data was quality checked and filtered before hashtag demultiplexing, unsupervised clustering and downstream analysis was implemented following the Seurat R package. Differential expression evaluated based on the non-parametric Wilcoxon rank sum test. Key genes determine by an adjusted p value of < 0.05 based on bonferroni correction and |avg log2FC| > 0.8.

Results

Preliminary analysis identifies 15 clusters with distinct CD45 immune phenotypes (figure 1). Differential gene expression analysis by hashtag antibody (treatment group) reveals 14 clusters differentially expressing key genes, including 3 clusters upregulated in DIPG compared to NML, and 2 clusters upregulated in irradiated tumors compared to SHAM and NML (figure 2). Notably, analysis demonstrates an individual cluster upregulated in FLASH versus all other groups (p = 3.07E-171). Further deconvolution of specific immune phenotypes represented by each cluster is ongoing.

Abstract 91 Figure 1

tSNE plot based on clustering of RNA signatures, grouped by RNA

Abstract 91 Figure 2

tSNE plot based on clustering of RNA signatures, grouped by hashtag antibody

Conclusions

Our preliminary analysis shows differential immune responses among DIPG tumors compared to NML. We also find several immune cell subsets that are unique to DIPG treated with CONV or FLASH compared to unirradiated samples. Most notably, we identify a single immune cell subset that is exclusive to FLASH alone, indicating that FLASH elicits a unique immune response in murine DIPG.

EPCT-23 PRE-CLINICAL STUDY OF FOCUSED ULTRASOUND-MEDIATED BLOOD-BRAIN BARRIER OPENING AND PANOBINOSTAT FOR DIFFUSE INTRINSIC PONTINE GLIOMA TREATMENT

Diffuse intrinsic pontine glioma (DIPG) is the lethal high-grade brain tumor in children with no effective treatment options to date. Despite excessive clinical trials, the prognosis remains poor, with a median overall survival (mOS) of less than 1 year. Genomic studies of DIPG tissue have identified highly recurrent mutations in genes encoding histone H3 resulting in the substitution of lysine to methionine at position 27 (K27M), which is found in approximately 80% of DIPG. Recent drug screening studies identified the histone deacetylase (HDAC) inhibitors panobinostat as a highly effective drug against DIPG in vitro. However, due to the poor Blood-Brain Barrier (BBB) penetration of systemic administration, to enhance the delivery of panobinostat to improve treatment efficacy is needed. Focused ultrasound (FUS) has been shown to be able to safely and non-invasively open BBB to enhance drug delivery. Hence, in this study, we hypothesize that FUS-mediated BBBO (BBBO) can enhance the delivery of panobinostat for a therapeutic benefit in DIPG. Herein we established the syngeneic DIPG model by intracranially injecting mouse DIPG cells (PDGFB+, H3.3K27M, p53−/−) and used FUS and microbubbles to open BBB and enhance the panobinostat delivery. Magnetic resonance (MR) imaging was utilized to evaluate BBBO and tumor progression. We first demonstrated that FUS-mediated BBB-opening is safe and feasible to mice with DIPG tumors by MR imaging and passive cavitation detection. Moreover, this DIPG cell line is very sensitive to panobinostat in in vitro cytotoxicity assay. The combined treatment of FUS-mediated BBBO and panobinostat showed benefits in both local control and overall survival. The current results demonstrated FUS could increase the treatment efficacy of panobinostat to DIPG animals may be due to the increase of targeted delivery of systemic panobinostat to DIPG tumors in brainstem.

EPCT-21. NEXT-GENERATION SEQUENCING OF CEREBROSPINAL FLUID FOR CLINICAL MOLECULAR DIAGNOSTICS IN ADOLESCENT AND YOUNG ADULT (AYA) BRAIN TUMOR PATIENTS

Purpose

Pediatric central nervous system tumors remain a leading cause of cancer-related death in children and adolescents. Safe sampling of tumor tissue for diagnostic purposes may be challenging. Subclinical detection of disease prior to clinical or imaging progression may provide opportunity for earlier intervention and ultimately improve overall survival. Additionally, our understanding of molecular evolution in response to therapy remains limited, given the rarity of serial sampling of tumor tissue.

Methods

We report our experience with minimally invasive molecular diagnostics using a validated next generation sequencing assay for sequencing of cerebrospinal fluid (CSF) cell-free DNA (cfDNA) obtained at the time of surgery, by intraventricular catheter or lumbar puncture. All CSF samples were collected as part of clinical care, and results reported to both clinicians and patients/families.

Results

We analyzed 64 CSF samples from 45 pediatric and adolescent and young adult (AYA) patients (pediatric=25; AYA=20) with primary and recurrent brain tumors across 12 histopathological subtypes including high-grade glioma (n=10), medulloblastoma (n=10), pineoblastoma (n=5), low grade glioma (n=4), diffuse leptomeningeal glioneuronal tumor (DLGNT) (n=4), metastatic retinoblastoma (n=4), ependymoma (n=3), and other (n=5). Somatic alterations were detected in 28/64 samples (44.4%) and in at least one sample per unique patient in 22/45 patients (48.8%). CSF cfDNA positivity was strongly associated with the presence of disseminated disease at the time of collection (86.3%). No association was seen between CSF cfDNA positivity and the timing of CSF collection during the patient’s disease course.

Conclusion

We identified four general categories where CSF cfDNA testing provided additional relevant diagnostic, prognostic, and/or therapeutic information, impacting clinical assessment and decision making: 1) diagnosis; 2) identification of actionable alterations; 3) track response to therapy; and 4) monitoring tumor evolution. Our findings support broader implementation of clinical CSF cfDNA testing in this population that may improve care.

DDEL-07. A PHASE I STUDY EXAMINING THE FEASIBILITY OF INTERMITTENT CONVECTION-ENHANCED DELIVERY (CED) OF MTX110 FOR THE TREATMENT OF CHILDREN WITH NEWLY DIAGNOSED DIFFUSE MIDLINE GLIOMAS

Convection-enhanced delivery (CED, the infusion of drugs under controlled pressure to the brain parenchyma via targeted micro-catheters, allows accurate anatomical targeting and delivery of higher (therapeutic) drug concentrations through clinically relevant volumes of brain tissue or tumor. Histone deacetylase inhibitors have been found in vitro to be the most active agents against Diffuse Midline Gliomas (DMGs) Using a novel device (implantable subcutaneous pump connected with catheter directly implanted into the pons/thalamus) we are performing a Phase I safety study of repeated infusions of MTX110 (MTX110, Midatech) in a dose escalation manner. Eligible patients include 3–18 years of age with newly diagnosed DMGs following radiation therapy without evidence of hemorrhage or cysts with intact organ function. Patients undergo a tumor biopsy and a single catheter (Spetzler lumbar shunt catheter, Integra, Plainsboro, NJ) is placed stereotactically into the geometric center of the tumor. A second catheter is inserted subcutaneously with the distal tubing connected to the infusion pump, (SynchroMed II (Medtronic)), also inserted subcutaneously. The infusion pump is prefilled with MTX110 and administered using wireless N’Vison Clinical programmer into two 24-hour infusions, consisting of 20 hours of drug infusions at 0.2mL/hr. The pulse is completed 7 days later. This is a dose escalation study with the infusate consisting of gadolinium and MTX110 (30, 60, or 90 microM). The study describing the first use in children of this device for direct-to-tumor drug delivery is open to recruitment (January 2020) and the preliminary data will be available for presentation by June 2020.

MODL-09. FEASIBILITY OF ACUTE SLICE CULTURE-SINGLE CELL SEQUENCING DRUG SCREENING AS A TOOL TO SELECT THERAPY FOR CHILDREN WITH RELAPSED BRAIN TUMORS

Children with relapsed brain tumors are less responsive to treatment. These children often receive therapies without having any robust predictive method of potential benefit. Acute slice culturing(ASC) is a methodology permitting freshly operated tumor to undergo a culturing process preserving the tumor’s micro-environment. With the current study, we investigated the feasibility of obtaining therapeutically meaningful data in a timely manner (3–5 days), performing direct drug testing and single cell sequencing using ASC. Previously, we have combined ex vivo slices of intact, patient-derived Glioblastoma tissue with single-cell RNA-seq for small-scale drug screening and assessment of patient and cell type-specific drug responses. We generated slices from preclinical mouse glioma models and surgical specimens from adult Glioblastoma patients, as well as from children with relapsed Ependymomas, Medulloblastomas, and Gliomas. We demonstrated that these acute slices preserved both the tumor heterogeneity and tumor microenvironment observed in single-cell RNA-seq of cells directly isolated from tumor tissue. Testing drug responses, we then treated tissue slices from the Glioblastoma mouse models and different patients with multiple drugs and combinations. This technique allowed us to identify drug-induced transcriptional responses in specific subpopulations of tumor cells, patient-specific drug sensitivities, and drug effects conserved in both mouse and human tumors. Preliminary data suggests that we can apply this procedure within 5–7 days and provide real-time drug screening/single cell sequencing ASC results to Recurrent/ Progressive pediatric Low-Grade Gliomas, High Grade Gliomas, Ependymomas and Medulloblastomas.

BIOM-56. THE INTEGRATION OF A LIQUID BIOPSY PROGRAM INTO THE CARE OF PEDIATRIC BRAIN TUMOR PATIENTS

Pediatric CNS tumors remain the leading cause of cancer-related death in children and adolescents. Safe sampling of tumor tissue for diagnostic purposes may be difficult if not impossible. Detection of minimal residual or recurrent disease prior to definitive clinical or radiographic progression may allow earlier initiation of novel therapies and ultimately improve overall survival. Given the rarity of serial sampling of tumor tissue, our understanding of molecular evolution in response to therapy remains limited. Recent technological advances have led to the development of “liquid biopsy” assays, which detect cell-free DNA (cfDNA) in blood, cerebrospinal fluid (CSF) or other bodily fluids. Here, we report our initial clinical experience with the recently established MSK Kids pediatric neuro-oncology liquid-biopsy program at Memorial Sloan Kettering Cancer Center (MSKCC) using MSK-IMPACT, which is clinically validated by the New York State Department of Health for CSF cell-free DNA (cfDNA)vprofiling. All CSF samples were collected as part of clinical care, and results reported to both clinicians and patients/families. Samples from 29 unique patients were sequenced. Histopathology included high-grade glioma (5); low-grade glioma (2); medulloblastoma (8); pineoblastoma (3); retinoblastoma (4); other (7). CSF cfDNA could be detected in 18/42 samples (43%) and 12/29 patients (34%). CSF cfDNA was more commonly detected in higher-grade, disseminated tumors such as high-grade glioma (60%), medulloblastoma (38%), and pineoblastoma (100%). Low-grade lesions without leptomeningeal involvement did not result in detectable CSF cfDNA shedding (86% were negative). In a subset of patients, MSK-IMPACT identified previously unrecognized molecular actionable targets (e.g. BRAF-KIAA1549 fusion); or the detection of “minimal residual disease” prior to the detection of tumor recurrence by conventional diagnostics, impacting clinical care decisions. Future directions include integration of CSF cfDNA into prospective clinical trials as a correlative biomarker.

Medulloblastoma: an Old Diagnosis with New Promises

PURPOSE OF REVIEW

Molecular subtyping in medulloblastoma (MB) has diagnostic and prognostic values which impact therapy. This paper provides guidance for the clinician caring for pediatric and adult patients with medulloblastoma in the modern era.

RECENT FINDINGS

Medulloblastoma comprises four molecularly distinct subgroups: wingless activated (WNT), sonic hedgehog activated (SHH), group 3, and group 4. Risk stratification before and after the discovery of molecular subgroups aims at minimizing toxicity by reducing radiation and chemotherapy doses in low-risk patients while maintaining favorable overall survival (OS). The mainstay of newly diagnosed medulloblastoma treatment is surgery, radiation therapy, and chemotherapy, except for children under 6 years of age, where high-dose chemotherapy with autologous stem cell rescue is used to avoid or delay radiotherapy, preventing neurocognitive sequelae. Management of recurrent/refractory medulloblastoma remains a challenge with immunotherapy and small-molecule inhibitors forming the backbone of novel strategies. Recent innovations in medulloblastoma research allow us to better understand pathogenesis and molecular characteristics resulting in advanced risk stratification models, new therapeutic approaches, and overall improved survival and quality of life.

Synthesis and structure-activity studies on novel analogs of human growth hormone releasing hormone (GHRH) with enhanced inhibitory activities on tumor growth

The syntheses and biological evaluations of new GHRH analogs of Miami (MIA) series with greatly increased anticancer activity are described. In the design and synthesis of these analogs, the following previous substitutions were conserved: D-Arg², Har⁹, Abu¹⁵, and Nle²⁷. Most new analogs had Ala at position 8. Since replacements of both Lys¹² and Lys²¹ with Orn increased resistance against enzymatic degradation, these modifications were kept. The substitutions of Arg at both positions 11 and 20 by His were also conserved. We kept D-Arg²⁸, Har²⁹ -NH₂ at the C-terminus or inserted Agm or 12-amino dodecanoic acid amide at position 30. We incorporated pentafluoro-Phe (Fpa₅), instead of Cpa, at position 6 and Tyr(Me) at position 10 and ω-amino acids at N-terminus of some analogs. These GHRH analogs were prepared by solid-phase methodology and purified by HPLC. The evaluation of the activity of the analogs on GH release was carried out in vitro on rat pituitaries and in vivo in male rats. Receptor binding affinities were measured in vitro by the competitive binding analysis. The inhibitory activity of the analogs on tumor proliferation in vitro was tested in several human cancer cell lines such as HEC-1A endometrial adenocarcinoma, HCT-15 colorectal adenocarcinoma, and LNCaP prostatic carcinoma. For in vivo tests, various cell lines including PC-3 prostate cancer, HEC-1A endometrial adenocarcinoma, HT diffuse mixed β cell lymphoma, and ACHN renal cell carcinoma cell lines were xenografted into nude mice and treated subcutaneously with GHRH antagonists at doses of 1-5μg/day. Analogs MIA-602, MIA-604, MIA-610, and MIA-640 showed the highest binding affinities, 30, 58, 48, and 73 times higher respectively, than GHRH (1-29) NH₂. Treatment of LNCaP and HCT-15 cells with 5μM MIA-602 or MIA-690 decreased proliferation by 40%-80%. In accord with previous tests in various human cancer lines, analog MIA-602 showed high inhibitory activity in vivo on growth of PC-3 prostate cancer, HT-mixed β cell lymphoma, HEC-1A endometrial adenocarcinoma and ACHN renal cell carcinoma. Thus, GHRH analogs of the Miami series powerfully suppress tumor growth, but have only a weak endocrine GH inhibitory activity. The suppression of tumor growth could be induced in part by the downregulation of GHRH receptors levels.

New therapeutic approach to heart failure due to myocardial infarction based on targeting growth hormone-releasing hormone receptor

Background

We previously showed that growth hormone-releasing hormone (GHRH) agonists are cardioprotective following myocardial infarction (MI). Here, our aim was to evaluate the in vitro and in vivo activities of highly potent new GHRH agonists, and elucidate their mechanisms of action in promoting cardiac repair.

Methods and Results

H9c2 cells were cultured in serum-free medium, mimicking nutritional deprivation. GHRH agonists decreased calcium influx and significantly improved cell survival. Rats with cardiac infarction were treated with GHRH agonists or placebo for four weeks. MI size was reduced by selected GHRH agonists (JI-38, MR-356, MR-409); this accompanied an increased number of cardiac c-kit⁺ cells, cellular mitotic divisions, and vascular density. One week post-MI, MR-409 significantly reduced plasma levels of IL-2, IL-6, IL-10 and TNF-α compared to placebo. Gene expression studies revealed favorable outcomes of MR-409 treatment partially result from inhibitory activity on pro-apoptotic molecules and pro-fibrotic systems, and by elevation of bone morphogenetic proteins.

Conclusions

Treatment with GHRH agonists appears to reduce the inflammatory responses post-MI and may consequently improve mechanisms of healing and cardiac remod eling by regulating pathways involved in fibrosis, apoptosis and cardiac repair. Patients with cardiac dysfunction could benefit from treatment with novel GHRH agonists.

Targeted cytotoxic analog of luteinizing hormone-releasing hormone (LHRH), AEZS-108 (AN-152), inhibits the growth of DU-145 human castration-resistant prostate cancer in vivo and in vitro through elevating p21 and ROS levels

Management of castration-resistant prostate cancer (CRPC) is challenging due to lack of efficacious therapy. Luteinizing hormone-releasing hormone (LHRH) analogs appear to act directly on cells based on the LHRH receptors on human prostate adenocarcinoma cells. We explored anticancer activity of a cytotoxic analog of LHRH, AEZS-108, consisting of LHRH agonist linked to doxorubicin. Nude mice bearing DU-145 tumors were used to compare antitumor effects of AEZS-108 with its individual constituents or their unconjugated combination. The tumor growth inhibition of conjugate was greatest among treatment groups (90.5% inhibition vs. 41% by [D-Lys(6)]LHRH+DOX). The presence of LHRH receptors on DU-145 cells was confirmed by immunocytochemistry. In vitro, AEZS-108 significantly inhibited cell proliferation (61.2% inhibition) and elevated apoptosis rates (by 46%). By the detection of the inherent doxorubicin fluorescence, unconjugated doxorubicin was seen in the nucleus; the conjugate was perinuclear and at cell membrane. Autophagy, visualized by GFP-tagged p62 reporter, was increased by AEZS-108 (7.9-fold vs. 5.3-fold by DOX+[D-Lys(6)]LHRH. AEZS-108 more effectively increased reactive oxygen species (ROS, 2-fold vs. 1.4-fold by DOX+[D-Lys(6)]LHRH) and levels of the apoptotic regulator p21 in vivo and in vitro. We demonstrate robust inhibitory effects of the targeted cytotoxic LHRH analog, AEZS-108, on LHRHR positive castration-resistant prostate cancer cells.

Triple negative breast cancers express receptors for LHRH and are potential therapeutic targets for cytotoxic LHRH-analogs, AEZS 108 and AEZS 125

BACKGROUND

Triple negative breast cancer (TNBC) is a distinct subtype of breast cancer burdened with a dismal prognosis due to the lack of effective therapeutic agents. Receptors for LHRH (luteinizing hormone-releasing hormone) can be successfully targeted with AEZS-108 [AN-152], an analog of LHRH conjugated to doxorubicin. Our study evaluates the presence of this target LHRH receptor in human specimens of TNBC and investigates the efficacy and toxicity of AEZS-108 in vivo. We also studied in vitro activity of AEZS-125, a new LHRH analog conjugated with the highly potent natural compound, Disorazol Z.

METHODS

69 human surgical specimens of TNBC were investigated for LHRH-R expression by immunohistochemistry. Expression of LHRH-R in two TNBC cell lines was evaluated by real time RT-PCR. Cytotoxicity of AEZS-125 was evaluated by Cell Titer Blue cytoxicity assay. LHRH- receptor expression was silenced with an siRNA in both cell lines. For the in vivo experiments an athymic nude mice model xenotransplanted with the cell lines, MDA-MB-231 and HCC 1806, was used. The animals were randomised to three groups receiving solvent only (d 1, 7, 14, i.v.) for control, AEZS-108 (d 1, 7, 14, i.v.) or doxorubicin at an equimolar dose (d 1, 7, 14, i.v.).

RESULTS

In human clinical specimens of TNBC, expression of the LHRH-receptor was present in 49% (n = 69).HCC 1806 and MDA-MB-231 TNBC cells expressed mRNA for the LHRH-receptor. Silencing of the LHRH-receptor significantly decreased the cytotoxic effect of AEZS-108. MDA-MB-231 and HCC 1806 tumors xenografted into nude mice were significantly inhibited by treatment with AEZS-108; doxorubicin at equimolar doses was ineffective.As compared to AEZS 108, the Disorazol Z - LHRH conjugate, AEZS-125, demonstrated an increased cytotoxicity in vitro in HCC 1806 and MDA-MB-231 TNBC; this was diminished by receptor blockade with synthetic LHRH agonist (triptorelin) pretreatment.

CONCLUSION

The current study confirms that LHRH-receptors are expressed by a significant proportion of TNBC and can be successfully used as homing sites for cytotoxic analogs of LHRH, such as AEZS-108 and AEZS-125.

Synthesis of new potent agonistic analogs of growth hormone-releasing hormone (GHRH) and evaluation of their endocrine and cardiac activities

In view of the recent findings of stimulatory effects of GHRH analogs, JI-34, JI-36 and JI-38, on cardiomyocytes, pancreatic islets and wound healing, three series of new analogs of GHRH(1-29) have been synthesized and evaluated biologically in an endeavor to produce more potent compounds. "Agmatine analogs", MR-356 (N-Me-Tyr(1)-JI-38), MR-361(N-Me-Tyr(1), D-Ala(2)-JI-38) and MR-367(N-Me-Tyr(1), D-Ala(2), Asn(8)-JI-38), in which Dat in JI-38 is replaced by N-Me-Tyr(1), showed improved relative potencies on GH release upon subcutaneous administration in vivo and binding in vitro. Modification with N-Me-Tyr(1) and Arg(29)-NHCH3 as in MR-403 (N-Me-Tyr(1), D-Ala(2), Arg(29)-NHCH3-JI-38), MR-406 (N-Me-Tyr(1), Arg(29)-NHCH3-JI-38) and MR-409 (N-Me-Tyr(1), D-Ala(2), Asn(8), Arg(29)-NHCH3-JI-38), and MR-410 (N-Me-Tyr(1), D-Ala(2), Thr(8), Arg(29)-NHCH3-JI-38) resulted in dramatically increased endocrine activities. These appear to be the most potent GHRH agonistic analogs so far developed. Analogs with Apa(30)-NH2 such as MR-326 (N-Me-Tyr(1), D-Ala(2), Arg(29), Apa(30)-NH2-JI-38), and with Gab(30)-NH2, as MR-502 (D-Ala(2), 5F-Phe(6), Ser(28), Arg(29),Gab(30)-NH2-JI-38) also exhibited much higher potency than JI-38 upon i.v. administration. The relationship between the GH-releasing potency and the analog structure is discussed. Fourteen GHRH agonists with the highest endocrine potencies were subjected to cardiologic tests. MR-409 and MR-356 exhibited higher potency than JI-38 in activating myocardial repair in rats with induced myocardial infarction. As the previous class of analogs, exemplified by JI-38, had shown promising results in multiple fields including cardiology, diabetes and wound healing, our new, more potent, GHRH agonists should manifest additional efficacy for possible medical applications.

Novel GHRH antagonists suppress the growth of human malignant melanoma by restoring nuclear p27 function

Malignant melanoma is the deadliest form of skin cancer; the treatment of advanced and recurrent forms remains a challenge. It has recently been reported that growth hormone-releasing hormone (GHRH) receptor is involved in the pathogenesis of melanoma. Therefore, we investigated the effects of our new GHRH antagonists on a human melanoma cancer cell line. Antiproliferative effects of GHRH antagonists, MIA-602, MIA-606 and MIA-690, on the human melanoma cell line, A-375, were studied in vitro using the MTS assay. The effect of MIA-690 (5 μg/day 28 d) was further evaluated in vivo in nude mice bearing xenografts of A-375. Subcellular localization of p27 was detected with Western blot and immunofluorescent staining. MIA-690 inhibited the proliferation of A-375 cells in a dose-dependent manner (33% at 10 μM, and 19.2% at 5 μM, P < 0 .05 vs. control), and suppressed the growth of xenografted tumors by 70.45% (P < 0.05). Flow cytometric analysis of cell cycle effects following the administration of MIA-690 revealed a decrease in the number of cells in G2/M phase (from 19.7% to 12.9%, P < 0.001). Additionally, Western blot and immunofluorescent studies showed that exposure of A-375 cells to MIA-690 triggered the nuclear accumulation of p27. MIA-690 inhibited tumor growth in vitro and in vivo, and increased the translocation of p27 into the nucleus thus inhibiting progression of the cell cycle. Our findings indicate that patients with malignant melanoma could benefit from treatment regimens, which combine existing chemotherapy agents and novel GHRH-antagonists.

Inhibition of U-87 MG glioblastoma by AN-152 (AEZS-108), a targeted cytotoxic analog of luteinizing hormone-releasing hormone

Glioblastoma multiforme is the most frequent tumor of the central nervous system in adults and has a dismal clinical outcome, which necessitates the development of new therapeutic approaches. We investigated in vivo the action of the targeted cytotoxic analog of luteinizing hormone releasing hormone, AN-152 (AEZS-108) in nude mice (Ncr nu/nu strain) bearing xenotransplanted U-87 MG glioblastoma tumors. We evaluated in vitro the expression of LHRH receptors, proliferation, apoptosis and the release of oncogenic and tumor suppressor cytokines. Clinical and U-87 MG samples of glioblastoma tumors expressed LHRH receptors. Treatment of nude mice with AN-152, once a week at an intravenous dose of 413 nmol/20g, for six weeks resulted in 76 % reduction in tumor growth. AN-152 nearly completely abolished tumor progression and elicited remarkable apoptosis in vitro. Genomic (RT-PCR) and proteomic (ELISA, Western blot) studies revealed that AN-152 activated apoptosis, as reflected by the changes in p53 and its regulators and substrates, inhibited cell growth, and elicited changes in intermediary filament pattern. AN-152 similarly reestablished contact regulation as demonstrated by expression of adhesion molecules and inhibited vascularization, as reflected by the transcription of angiogenic factors. Our findings suggest that targeted cytotoxic analog AN-152 (AEZS-108) should be considered for a treatment of glioblastomas.

Beneficial effects of novel antagonists of GHRH in different models of Alzheimer's disease

Alzheimer's disease is the most frequent debilitating disorder of the central nervous system. Neuroendocrine mechanisms appear to play an important role in this insidiously developing disease. In the present study, the effects of a recently developed growth hormone-releasing hormone (GHRH) antagonist (MIA-690) were evaluated in vivo observing the behavior of genetically modified "Alzheimer's" 5XFAD mice in a Morris water maze (MWM). The effects of the antagonist were also evaluated in vitro using HCN2 human cortical cell cultures treated with amyloid-β1-42. In vivo, the indices of cognitive performance (latency, cumulative index etc.) were followed up for 6 months. In vitro, the formation of reactive oxygen species, markers of inflammatory and neurohormonal signaling were measured by fluorescent detection, PCR, and ELISA. Accumulation of amyloid-β1-42 rafts and τ filaments in necropsied brain samples was verified with the help of ELISA. In the MWM experiments, MIA-690 decreased escape latency, and, in the brain samples, it inhibited the concentration of amyloid-β1-42 and τ filaments. In cell cultures, the GHRH analog showed anti-oxidative and neuro-protective properties and inhibited the GHRH-growth hormone-insulin like growth factor axis. Our data strongly suggest the merit of further studies with GHRH analogs in models of Alzheimer's disease and in elementary clinical trials.

Mechanisms of synergism between antagonists of growth hormone-releasing hormone and antagonists of luteinizing hormone-releasing hormone in shrinking experimental benign prostatic hyperplasia

BACKGROUND

Benign prostatic hyperplasia (BPH) affects aging men. Combined therapy with antagonists of growth hormone-releasing hormone (GHRH) and of luteinizing hormone-releasing hormone (LHRH or GnRH) induces prostate shrinkage in rat models. We investigated the mechanisms of action of this combination on cell cycle traverse and expression of prostatic genes.

METHODS

Effects of GHRH antagonist, JMR-132 (40 µg/day), the LHRH antagonist, cetrorelix (0.625 mg/kg), and their combination were evaluated on testosterone-induced benign prostatic hyperplasia in male Wistar rats. Influence of JMR-132, cetrorelix, and their combinations on cell viability was assessed by MTS assay in BPH-1 human prostate epithelial cells and WPMY-1 normal prostate stromal cells. Cell cycle was analyzed by laser flow cytometry. Real-time PCR arrays were performed.

RESULTS

The combination of antagonists caused marked shrinkage of rat prostate (29.5%). In vitro, JMR-132 plus cetrorelix (both 5µM) produced synergistic (57.4%) inhibition of growth of BPH-1 cells, but a lesser inhibition (46%) of WPMY-1 cells. Co-treatment of with JMR-132 plus cetrorelix induced a significant increase of BPH-1 cells blocked in S-phase plus cells with lower G0 /G1 and G2 /M DNA content. Significant changes in expression of >40 gene transcripts related to growth factors, inflammatory cytokines, and signal transduction were identified.

CONCLUSIONS

GHRH antagonist and LHRH antagonist combination potentiates rat prostate weight reduction and synergistically inhibits of growth of BPH-1 leading to cell cycle arrest in S-phase. These effects were lesser in normal stromal prostate cell line, WPMY-1. Our findings suggest that GHRH antagonists could be useful for BPH therapy, possibly in combination with LHRH antagonists.

Combination of GHRH antagonists and docetaxel shows experimental effectiveness for the treatment of triple-negative breast cancers

In preclinical studies, antagonists of growth hormone-releasing hormone (GHRH) have demonstrated inhibitory effects on the growth of various types of cancers expressing the pituitary type of GHRH receptors (pGHRH-R) and/or its active splice variant 1 (SV1). In this study, we investigated the effectiveness of the treatment of MDA-MB-231 human triple-negative breast cancer (TNBC) with GHRH antagonist JMR-132 alone or in combination with docetaxel. Receptor expression in the MDA-MB-231 human breast cancer cell line was evaluated by reverse transcription-polymerase chain reaction (RT-PCR). Cell viability assays were performed on MDA-MB-231 cells treated with JMR-132, docetaxel or in combination. For studies in vivo, a subcutaneous nude mouse xenograft model was used. JMR-132 was administered s.c. at a dose of 10 µg/day and docetaxel at a dose of 10 mg/kg i.p. given on day 1 and 5. Similar regimens were used for the combination of both substances. At the end of the experiment, an mRNA-based human cancer pathway array including 84 major genes was performed on the tumor tissue of mice treated with JMR-132 to elucidate the mechanism of action of GHRH antagonists in vivo. The in vitro proliferation studies revealed that JMR-132 and docetaxel decreased the cell viability in a dose-dependent manner. The combination of both treatments produced a significantly greater inhibition of cell viability compared to the single agents. Treatment of nude mice bearing MDA-MB-231 xenografts with JMR-132 and docetaxel significantly (p<0.05) inhibited tumor growth by 46 and 50%, respectively. Treatment with the combination of JMR-132 and docetaxel led to an inhibition of tumor volume by 71.6% (p<0.001). Polymerase chain reaction array analysis revealed that JMR-132 interacts with signal transduction pathways involved in proliferation, apoptosis and angiogenesis. Our results suggest that GHRH antagonists in combination with taxanes may enhance the efficacy of treatment for patients with TNBC expressing the SV1 and/or the pGHRH receptor.

Experimental therapy of PC-3 and DU-145 human androgen-independent prostate cancers with targeted cytotoxic analog of somatostatin AN-162

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Background: Management of castration-resistant prostate cancer (CRPC) is challenging because of limitations in efficacy of current therapies. Somatostatin receptors are expressed in human CRPC. Here we tested targeted somatostatin AN-162 analog consisting of doxorubicin (DOX) conjugated to octapeptide RC-121, acting as a carrier, in human androgen-independent prostate cancer cell lines in vitro and in vivo. Methods: Expression of mRNA for the five subtypes of the somatostatin receptor in PC-3 and DU-145 human prostate cancer cell lines was evaluated by RT-PCR. Somatostatin receptor binding was measured with radioligand assays. The effect of AN-162 and DOX on the viability of PC-3 and DU-145 cells was assessed by MTS assay. Nude mice bearing PC-3 and DU-145 tumors were randomized to 5 groups (control, AN-162, DOX, somatostatin analog RC-160 as a control, and DOX + RC-160). Treatment consisted i.v. injections of AN-162, DOX, RC-160, DOX + RC-160, or vehicle once a week for 4 weeks. Tumor volume was measured every week; the study lasted 28 days. The doses of AN-162 were equivalent to 1.45 mg/kg DOX (2.5 μmol/kg). Results: The PC-3 and DU-145 cell lines were positive for the five subtypes of the somatostatin receptor. AN-162 and DOX (0.10–10 µM) inhibited the proliferation of PC-3 and DU-145 prostate cancer cells in a dose-dependent manner. AN-162 exerted a stronger inhibition of proliferation than DOX alone, but in vitro the difference was not significant. In vivo, AN-162 significantly inhibited growth of both tumor models’ compared with the controls and the groups given equimolar doses of doxorubicin, RC-160, or doxorubicin unconjugated to RC-160. Conclusions: Our work demonstrates potent inhibitory effects of AN-162 on somatostatin receptor positive androgen-independent prostate cancers, which were greater than any of the components of AN-162. The mechanisms of action of targeted cytotoxic analog of somatostatin AN-162 in CRPC should be explored. Our findings suggest the possible use of AN-162 in patients with CRPC.

Effect of novel growth hormone-releasing hormone antagonists on growth of experimental renal cell carcinomas

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Background: Although targeted therapy has improved the clinical outcome for patients with metastatic renal cell carcinoma (RCC), a complete response is rare and therapy has adverse effects. Early antagonists of growth hormone-releasing hormone (GHRH) were shown to inhibit experimental RCC cell line, Caki-1, in vitro and in vivo. Herein, we investigate the effects of novel and highly potent antagonists of GHRH of MIA class on the growth of three RCC cell lines. Methods: The expression of GHRH receptor in all three cell lines was evaluated by ligand competition studies. The influence of GHRH antagonists MIA-602, MIA-604, MIA-606, and MIA-690 on cell viability was assessed by MTS assay in ACHN, A498, and 786-0 human RCC cells. GHRH antagonists were given at dose of 5µg daily in these three nude-mice xenograft models. Cell cycle parameters were analyzed by laser flow cytometry. Results: Ligand competition studies revealed specific, high affinity binding sites for GHRH receptor in all three RCC cell lines. GHRH antagonists inhibited the proliferation of all three RCC cells in a dose dependent manner. GHRH antagonists caused significant inhibition of tumor growth of ACHN, A498, and 786-0 RCCs ranged from 53-75% after 35 days of treatment (p<0.001). Treatment of ACHN cells with MIA-690 (10µM) led to a significant increase in number of cells with subG1DNA content, suggesting apoptosis. Conclusions: The effectiveness of the novel GHRH antagonists in inhibiting growth of experimental RCC models in vitro and in vivo was demonstrated. The inhibitory effect of GHRH antagonists is mainly due to direct inhibitory effects exerted through GHRH receptors. Biochemical and histological evaluation is needed to explore the mechanisms of action of GHRH antagonists in RCC.

Suppression of the proliferation of human U-87 MG glioblastoma cells by new antagonists of growth hormone-releasing hormone in vivo and in vitro

Five-year survival of patients afflicted with glioblastoma multiforme (GBM) is rare, making this cancer one of the most feared malignancies. Previously, we reported that growth hormone-releasing hormone (GHRH) is a potent growth factor in cancers. The present work evaluated the effects of two antagonistic analogs of GHRH (MIA-604 and MIA-690) on the proliferation of U-87 MG GBM tumors, in vivo as well as in vitro. Both analogs were administered subcutaneously and dose-dependently inhibited the growth of tumors transplanted into nude mice (127 animals in seven groups). The analogs also inhibited cell proliferation in vitro, decreased cell size, and promoted apoptotic and autophagic processes. Both antagonists stimulated contact inhibition, as indicated by the expression of the E-cadherin-β-catenin complex and integrins, and decreased the release of humoral regulators of glial growth such as FGF, PDGFβ, and TGFβ, as revealed by genomic or proteomic detection methods. The GHRH analogs downregulated other tumor markers (Jun-proto-oncogene, mitogen-activated protein kinase-1, and melanoma cell adhesion molecule), upregulated tumor suppressors (p53, metastasis suppressor-1, nexin, TNF receptor 1A, BCL-2-associated agonist of cell death, and ifκBα), and inhibited the expression of the regulators of angiogenesis and invasion (angiopoetin-1, VEGF, matrix metallopeptidase-1, S100 calcium binding protein A4, and synuclein-γ). Our findings indicate that GHRH antagonists inhibit growth of GBMs by multiple mechanisms and decrease both tumor cell size and number.

GHRH antagonist when combined with cytotoxic agents induces S-phase arrest and additive growth inhibition of human colon cancer

Treatment of colon cancer with an antagonist of growth hormone-releasing hormone (GHRH), JMR-132, results in a cell cycle arrest in S-phase of the tumor cells. Thus, we investigated the effect of JMR-132 in combination with S-phase-specific cytotoxic agents, 5-FU, irinotecan and cisplatin on the in vitro and in vivo growth of HT-29, HCT-116 and HCT-15 human colon cancer cell lines. In vitro, every compound inhibited proliferation of HCT-116 cells in a dose-dependent manner. Treatment with JMR-132 (5 μM) combined with 5-FU (1.25 μM), irinotecan (1.25 μM) or cisplatin (1.25 μM) resulted in an additive growth inhibition of HCT-116 cells in vitro as shown by MTS assay. Cell cycle analyses revealed that treatment of HCT-116 cells with JMR-132 was accompanied by a cell cycle arrest in S-phase. Combination treatment using JMR-132 plus a cytotoxic drug led to a significant increase of the sub-G 1 fraction, suggesting apoptosis. In vivo, daily treatment with GHRH antagonist JMR-132 decreased the tumor volume by 40-55% (p < 0.001) of HT-29, HCT-116 and HCT-15 tumors xenografted into athymic nude mice. Combined treatment with JMR-132 plus chemotherapeutic agents 5-FU, irinotecan or cisplatin resulted in an additive tumor growth suppression of HT-29, HCT-116 and HCT-15 xenografts to 56-85%. Our observations indicate that JMR-132 enhances the antiproliferative effect of S-phase-specific cytotoxic drugs by causing accumulation of tumor cells in S-phase.

Receptor-targeted therapy of human experimental urinary bladder cancers with cytotoxic LH-RH analog AN-152 [AEZS- 108]

Many bladder cancers progress to invasion with poor prognosis; new therapeutic methods are needed. We developed a cytotoxic LH-RH analog, AN-152 (AEZS-108) containing doxorubicin (DOX), for targeted therapy of cancers expressing LHRH receptors. We investigated the expression of LH-RH receptors in clinical bladder cancers and in HT-1376, J82, RT-4 and HT-1197 human bladder cancer lines. The effect of analog, AN-152, on growth of these tumor lines xenografted into nude mice was analyzed. Using molecular and functional assays, we also evaluated the differences between the effects of AN-152, and DOX alone. We demonstrated the expression of LH-RH receptors on 18 clinical bladder cancers by immunohistochemistry and on four human urinary bladder cancer lines HT-1376, J82, RT-4 and HT-1197 by Western blotting and binding assays. AN-152 powerfully inhibited growth of these bladder cancers in nude mice. AN-152 exerted greater effects than DOX and was less toxic. DOX activated strong multidrug resistance mechanisms in RT-4 and HT-1197 cancers, while AN-152 had no or less such effect. PCR assays and in vitro studies revealed differences in the action of AN-152 and DOX on the expression of genes involved in apoptosis. These results suggest that targeted cytotoxic LH-RH analog, AN-152 (AEZS- 108), should be examined for treatment of patients with LH-RH receptor positive invasive bladder cancers.

Combination of gastrin-releasing peptide antagonist with cytotoxic agents produces synergistic inhibition of growth of human experimental colon cancers

We investigated the efficacy of a powerful antagonist of bombesin/gastrin-releasing peptide (BN/GRP) RC-3940-II administered as a single agent or in combination with cytotoxic agents on the growth of HT-29, HCT-116 and HCT-15 human colon cancer in vitro and in vivo. GRP-receptor mRNA and protein were found in all three cell lines tested. Exposure of HT-29 cells to 10 μM RC-3940-II led to an increase in the number of cells blocked in S phase and G 2/M and cells with lower G(0)/G(1) DNA content. Similar changes on the cell cycle traverse of HT-29 cells could also be seen at lower concentrations of RC-3940-II (1 μM) after pretreatment with 100 nM GRP (14-27), indicating a dose-dependent mechanism of action based on the blockage of BN/GRP induced proliferation of tumor cells at lower concentrations. Daily in vivo treatment with BN/GRP antagonist RC-3940-II decreased the volume of HT-29, HCT-116 and HCT-15 tumors xenografted into athymic nude mice by 25 to 67% (p < 0.005). Combined treatment with RC-3940-II and chemotherapeutic agents 5-FU and irinotecan resulted in a synergistic tumor growth suppression of HT-29, HCT-116 and HCT-15 xenografts by 43% to 78%. In HT-29 and HCT-116 xenografts the inhibition for the combinations of RC-3940-II and irinotecan vs. single substances (p < 0.05) was significantly greater. These findings support the use of RC-3940-II as an anticancer agent and may help to design clinical trials using RC-3940-II in combinations with cytotoxic agents.

Combining growth hormone-releasing hormone antagonist with luteinizing hormone-releasing hormone antagonist greatly augments benign prostatic hyperplasia shrinkage

PURPOSE

Benign prostatic hyperplasia often affects aging men. Antagonists of the neuropeptide growth hormone-releasing hormone reduced prostate weight in an androgen induced benign prostatic hyperplasia model in rats. Luteinizing hormone-releasing hormone antagonists also produce marked, protracted improvement in lower urinary tract symptoms, reduced prostate volume and an increased urinary peak flow rate in men with benign prostatic hyperplasia. We investigated the influence of a combination of antagonists of growth hormone-releasing hormone and luteinizing hormone-releasing hormone on animal models of benign prostatic hyperplasia.

MATERIALS AND METHODS

We evaluated the effects of the growth hormone-releasing hormone antagonist JMR-132, given at a dose of 40 μg daily, the luteinizing hormone-releasing hormone antagonist cetrorelix, given at a dose of 0.625 mg/kg, and their combination on testosterone induced benign prostatic hyperplasia in adult male Wistar rats in vivo. Prostate tissue was examined biochemically and histologically. Serum levels of growth hormone, luteinizing hormone, insulin-like growth factor-1, dihydrotestosterone and prostate specific antigen were determined.

RESULTS

Marked shrinkage of the rat prostate (30.3%) occurred in response to the combination of growth hormone-releasing hormone and luteinizing hormone-releasing hormone antagonists (p<0.01). The combination strongly decreased prostatic prostate specific antigen, 6-transmembrane epithelial antigen of the prostate, interleukin-1β, nuclear factor-κβ and cyclooxygenase-2, and decreased serum prostate specific antigen.

CONCLUSIONS

A combination of growth hormone-releasing hormone antagonist with luteinizing hormone-releasing hormone antagonist potentiated a reduction in prostate weight in an experimental benign prostatic hyperplasia model. Results suggest that this shrinkage in prostate volume was induced by the direct inhibitory effects of growth hormone-releasing hormone and luteinizing hormone-releasing hormone antagonists exerted through their respective prostatic receptors. These findings suggest that growth hormone-releasing hormone antagonists and/or their combination with luteinizing hormone-releasing hormone antagonists should be considered for further development as therapy for benign prostatic hyperplasia.

Inhibitory effects of GHRH antagonists on human GH-secreting adenoma tissue

Experimental data indicate that antagonists of growth hormone-releasing hormone (GHRH) could be used clinically in disorders characterized by excessive GHRH/growth hormone (GH) secretion, but direct evidence for the effectiveness of GHRH antagonists on human pituitary tissue is still lacking. In this study, we investigated the inhibitory effect of our GHRH antagonists MZ-4-71 and JV-1-36 and the somatostatin (SST) analog RC-160 on superfused pituitary cells obtained from a human GH-secreting adenoma. Using Western blot analysis and immunohistochemistry, we demonstrated profuse expression of the GHRH receptor and its major splice variant SV1 and an increase in the expression of Gsa protein in the adenoma tissue. Exposure of the tumor cells to exogenous pulses of GHRH induced definite GH responses, causing a 3- to 5-fold elevation of the basal GH level. The antagonists MZ-4-71 and JV-1-36 did not alter basal GH secretion, indicating that the adenoma cells did not secrete GHRH in an autocrine manner. However, both antagonists prevented the stimulatory effect of exogenous GHRH. Similarly to the GHRH antagonists, neither SST-14 nor the SST analog RC-160 had an effect on the basal GH secretion of the tumor cells, but both peptides inhibited the stimulatory effect of exogenous GHRH, with RC-160 being more potent than SST. Our study provides direct evidence for the effectiveness of potent GHRH antagonists such as MZ-4-71 and JV-1-36 on human pituitary GH-secreting adenoma tissue and strongly suggests that these drugs could be used for therapy of GHRH-associated forms of acromegaly, particularly for those patients in whom surgery fails or is not an option.

Growth hormone-releasing hormone antagonists inhibit growth of human ovarian cancer

Epithelial ovarian carcinoma is the leading cause of cancer-related deaths among women with gynecologic malignancies. Antagonists of the growth hormone-releasing hormone (GHRH) have been shown to inhibit growth of various cancers through endocrine, autocrine, and paracrine mechanisms. In this study, we have investigated the effects of GHRH antagonists (GHRHa) in ES-2 human clear cell ovarian cancer and in UCI-107 human serous ovarian cancer in vitro and in vivo. We evaluated the expression of mRNA for GHRH receptor, the binding to GHRH receptors, in specimens of ES-2 ovarian cancer. We evaluated also the in vitro effects of GHRHa on ES-2 cells and the in vivo effect of 2 different GHRHa on ES-2 and UCI-107 tumors. Nude mice bearing xenografts on ES-2 and UCI-107 ovarian cancer were treated with JMR-132 and MZ-J-7-118, respectively. Tumor growth was compared to control. ES-2 cells expressed mRNA for the functional splice variant SV1 of the GHRH receptor. JMR-132 inhibited cell proliferation in vitro by 42% and 18% at 10 and 1 μM concentration, respectively. Specific high affinity receptors for GHRH were detected in ES-2 cancer samples. In vivo daily subcutaneous injections of GHRHa significantly reduced tumor growth compared to a control group in both animal models. Our results indicate that GHRHa such as JMR-132 and MZ-J-7-118 can inhibit the growth of human ovarian cancer. The efficacy of GHRHa in ovarian cancer should be assessed in clinical trials.

Novel antagonists of growth hormone-releasing hormone inhibit growth and vascularization of human experimental ovarian cancers

BACKGROUND

Antagonists of growth hormone-releasing hormone (GHRH) inhibit the proliferation of various human cancer cell lines and experimental tumors by mechanisms that include direct action on GHRH receptors in cancer cells.

METHODS

In this study, the effects of newly synthesized GHRH antagonists, MIA-313, MIA-602, MIA-604, and MIA-610, were investigated in 2 human ovarian epithelial adenocarcinoma cell lines, OVCAR-3 and SKOV-3, in vitro and in vivo. The expression of receptors for GHRH was demonstrated by Western blot analysis and ligand competition methods in the OVCAR-3 and SKOV-3 cell lines and in tumors from those cells grown in athymic nude mice. The effects of GHRH antagonists on the secretion of vascular endothelial growth factor (VEGF) by OVCAR-3 cells and on the vascularization of OVCAR-3 xenografts also were evaluated.

RESULTS

Both the pituitary and the splice variant type 1 (SV1) GHRH receptors were detected in the 2 cell lines and in tumor xenografts, and SV1 was expressed at higher levels. Cell viability assays revealed the antiproliferative effect of all GHRH antagonists that were. Maximal tumor growth inhibition was approximately 75% in both models. MIA-313 and MIA-602 decreased VEGF secretion of OVCAR-3 cells, as measured by enzyme-linked immunosorbent assay, and reduced tumor vascularization in a Matrigel plug assay, but caused no change in the expression of VEGF or VEGF receptor in the terminal ileum of mice with OVCAR-3 tumors.

CONCLUSIONS

Results from the current study indicated that a he novel approach based on GHRH antagonists may offer more effective therapeutic alternatives for patients with advanced ovarian cancer and who do not tolerate conventional anti-VEGF therapy.