Afamitresgene autoleucel for advanced synovial sarcoma and myxoid round cell liposarcoma (SPEARHEAD-1): an international, open-label, phase 2 trial.

BACKGROUND: Afamitresgene autoleucel (afami-cel) showed acceptable safety and promising efficacy in a phase 1 trial (NCT03132922). The aim of this study was to further evaluate the efficacy of afami-cel for the treatment of patients with HLA-A*02 and MAGE-A4-expressing advanced synovial sarcoma or myxoid round cell liposarcoma. METHODS: SPEARHEAD-1 was an open-label, non-randomised, phase 2 trial done across 23 sites in Canada, the USA, and Europe. The trial included three cohorts, of which the main investigational cohort (cohort 1) is reported here. Cohort 1 included patients with HLA-A*02, aged 16-75 years, with metastatic or unresectable synovial sarcoma or myxoid round cell liposarcoma (confirmed by cytogenetics) expressing MAGE-A4, and who had received at least one previous line of anthracycline-containing or ifosfamide-containing chemotherapy. Patients received a single intravenous dose of afami-cel (transduced dose range 1·0 × 109-10·0 × 109 T cells) after lymphodepletion. The primary endpoint was overall response rate in cohort 1, assessed by a masked independent review committee using Response Evaluation Criteria in Solid Tumours (version 1.1) in the modified intention-to-treat population (all patients who received afami-cel). Adverse events, including those of special interest (cytokine release syndrome, prolonged cytopenia, and neurotoxicity), were monitored and are reported for the modified intention-to-treat population. This trial is registered at ClinicalTrials.gov, NCT04044768; recruitment is closed and follow-up is ongoing for cohorts 1 and 2, and recruitment is open for cohort 3. FINDINGS: Between Dec 17, 2019, and July 27, 2021, 52 patients with cytogenetically confirmed synovial sarcoma (n=44) and myxoid round cell liposarcoma (n=8) were enrolled and received afami-cel in cohort 1. Patients were heavily pre-treated (median three [IQR two to four] previous lines of systemic therapy). Median follow-up time was 32·6 months (IQR 29·4-36·1). Overall response rate was 37% (19 of 52; 95% CI 24-51) overall, 39% (17 of 44; 24-55) for patients with synovial sarcoma, and 25% (two of eight; 3-65) for patients with myxoid round cell liposarcoma. Cytokine release syndrome occurred in 37 (71%) of 52 of patients (one grade 3 event). Cytopenias were the most common grade 3 or worse adverse events (lymphopenia in 50 [96%], neutropenia 44 [85%], leukopenia 42 [81%] of 52 patients). No treatment-related deaths occurred. INTERPRETATION: Afami-cel treatment resulted in durable responses in heavily pre-treated patients with HLA-A*02 and MAGE-A4-expressing synovial sarcoma. This study shows that T-cell receptor therapy can be used to effectively target solid tumours and provides rationale to expand this approach to other solid malignancies. FUNDING: Adaptimmune.

Autologous T cell therapy for MAGE-A4+ solid cancers in HLA-A*02+ patients: a phase 1 trial.

Affinity-optimized T cell receptors can enhance the potency of adoptive T cell therapy. Afamitresgene autoleucel (afami-cel) is a human leukocyte antigen-restricted autologous T cell therapy targeting melanoma-associated antigen A4 (MAGE-A4), a cancer/testis antigen expressed at varying levels in multiple solid tumors. We conducted a multicenter, dose-escalation, phase 1 trial in patients with relapsed/refractory metastatic solid tumors expressing MAGE-A4, including synovial sarcoma (SS), ovarian cancer and head and neck cancer ( NCT03132922 ). The primary endpoint was safety, and the secondary efficacy endpoints included overall response rate (ORR) and duration of response. All patients (N = 38, nine tumor types) experienced Grade ≥3 hematologic toxicities; 55% of patients (90% Grade ≤2) experienced cytokine release syndrome. ORR (all partial response) was 24% (9/38), 7/16 (44%) for SS and 2/22 (9%) for all other cancers. Median duration of response was 25.6 weeks (95% confidence interval (CI): 12.286, not reached) and 28.1 weeks (95% CI: 12.286, not reached) overall and for SS, respectively. Exploratory analyses showed that afami-cel infiltrates tumors, has an interferon-γ-driven mechanism of action and triggers adaptive immune responses. In addition, afami-cel has an acceptable benefit-risk profile, with early and durable responses, especially in patients with metastatic SS. Although the small trial size limits conclusions that can be drawn, the results warrant further testing in larger studies.

Phase 1 Clinical Trial Evaluating the Safety and Anti-Tumor Activity of ADP-A2M10 SPEAR T-Cells in Patients With MAGE-A10+ Head and Neck, Melanoma, or Urothelial Tumors.

Background: ADP-A2M10 specific peptide enhanced affinity receptor (SPEAR) T-cells are genetically engineered autologous T-cells that express a high-affinity melanoma-associated antigen (MAGE)-A10-specific T-cell receptor (TCR) targeting MAGE-A10-positive tumors in the context of human leukocyte antigen (HLA)-A*02. ADP-0022-004 is a phase 1, dose-escalation trial to evaluate the safety and anti-tumor activity of ADP-A2M10 in three malignancies (https://clinicaltrials.gov: NCT02989064). Methods: Eligible patients were HLA-A*02 positive with advanced head and neck squamous cell carcinoma (HNSCC), melanoma, or urothelial carcinoma (UC) expressing MAGE-A10. Patients underwent apheresis; T-cells were isolated, transduced with a lentiviral vector containing the MAGE-A10 TCR, and expanded. Patients underwent lymphodepletion with fludarabine and cyclophosphamide prior to receiving ADP-A2M10. ADP-A2M10 was administered in two dose groups receiving 0.1×109 and >1.2 to 6×109 transduced cells, respectively, and an expansion group receiving 1.2 to 15×109 transduced cells. Results: Ten patients (eight male and two female) with HNSCC (four), melanoma (three), and UC (three) were treated. Three patients were treated in each of the two dose groups, and four patients were treated in the expansion group. The most frequently reported adverse events grade ≥3 were leukopenia (10), lymphopenia (10), neutropenia (10), anemia (nine), and thrombocytopenia (five). Two patients reported cytokine release syndrome (one each with grade 1 and grade 3), with resolution. Best response included stable disease in four patients, progressive disease in five patients, and not evaluable in one patient. ADP-A2M10 cells were detectable in peripheral blood from patients in each dose group and the expansion group and in tumor tissues from patients in the higher dose group and the expansion group. Peak persistence was greater in patients from the higher dose group and the expansion group compared with the lower dose group. Conclusions: ADP-A2M10 has shown an acceptable safety profile with no evidence of toxicity related to off-target binding or alloreactivity in these malignancies. Persistence of ADP-A2M10 in the peripheral blood and trafficking of ADP-A2M10 into the tumor was demonstrated. Because MAGE-A10 expression frequently overlaps with MAGE-A4 expression in tumors and responses were observed in the MAGE-A4 trial (NCT03132922), this clinical program closed, and trials with SPEAR T-cells targeting the MAGE-A4 antigen are ongoing.

Phase I clinical trial evaluating the safety and efficacy of ADP-A2M10 SPEAR T cells in patients with MAGE-A10+ advanced non-small cell lung cancer.

BACKGROUND: ADP-A2M10 specific peptide enhanced affinity receptor (SPEAR) T cells (ADP-A2M10) are genetically engineered autologous T cells that express a high-affinity melanoma-associated antigen A10 (MAGE-A10)-specific T-cell receptor (TCR) targeting MAGE-A10+ tumors in the context of human leukocyte antigen (HLA)-A*02. ADP-0022-003 was a phase I dose-escalation trial that aimed to evaluate the safety and antitumor activity of ADP-A2M10 in non-small cell lung cancer (NSCLC) (NCT02592577). METHODS: Eligible patients were HLA-A*02 positive with advanced NSCLC expressing MAGE-A10. Patients underwent apheresis; T cells were isolated, transduced with a lentiviral vector containing the TCR targeting MAGE-A10, and expanded. Patients underwent lymphodepletion with varying doses/schedules of fludarabine and cyclophosphamide prior to receiving ADP-A2M10. ADP-A2M10 were administered at 0.08-0.12×109 (dose group 1), 0.5-1.2×109 (dose group 2), and 1.2-15×109 (dose group 3/expansion) transduced cells. RESULTS: Eleven patients (male, n=6; female, n=5) with NSCLC (adenocarcinoma, n=8; squamous cell carcinoma, n=3) were treated. Five, three, and three patients received cells in dose group 1, dose group 2, and dose group 3/expansion, respectively. The most frequently reported grade ≥3 adverse events were lymphopenia (n=11), leukopenia (n=10), neutropenia (n=8), anemia (n=6), thrombocytopenia (n=5), and hyponatremia (n=5). Three patients presented with cytokine release syndrome (grades 1, 2, and 4, respectively). One patient received the highest dose of lymphodepletion (fludarabine 30 mg/m2 on days -5 to -2 and cyclophosphamide 1800 mg/m2 on days -5 to -4) prior to a second infusion of ADP-A2M10 and had a partial response, subsequently complicated by aplastic anemia and death. Responses included: partial response (after second infusion; one patient), stable disease (four patients), clinical or radiographic progressive disease (five patients), and not evaluable (one patient). ADP-A2M10 were detectable in peripheral blood and in tumor tissue. Peak persistence was higher in patients who received higher doses of ADP-A2M10. CONCLUSIONS: ADP-A2M10 demonstrated an acceptable safety profile and no evidence of toxicity related to off-target binding or alloreactivity. There was persistence of ADP-A2M10 in peripheral blood as well as ADP-A2M10 trafficking into the tumor. Given the discovery that MAGE-A10 and MAGE-A4 expression frequently overlap, this clinical program closed as trials with SPEAR T cells targeting MAGE-A4 are ongoing.

Systemic and local immunity following adoptive transfer of NY-ESO-1 SPEAR T cells in synovial sarcoma.

BACKGROUND: Gene-modified autologous T cells expressing NY-ESO-1c259, an affinity-enhanced T-cell receptor (TCR) reactive against the NY-ESO-1-specific HLA-A*02-restricted peptide SLLMWITQC (NY-ESO-1 SPEAR T-cells; GSK 794), have demonstrated clinical activity in patients with advanced synovial sarcoma (SS). The factors contributing to gene-modified T-cell expansion and the changes within the tumor microenvironment (TME) following T-cell infusion remain unclear. These studies address the immunological mechanisms of response and resistance in patients with SS treated with NY-ESO-1 SPEAR T-cells. METHODS: Four cohorts were included to evaluate antigen expression and preconditioning on efficacy. Clinical responses were assessed by RECIST v1.1. Engineered T-cell persistence was determined by qPCR. Serum cytokines were evaluated by immunoassay. Transcriptomic analyses and immunohistochemistry were performed on tumor biopsies from patients before and after T-cell infusion. Gene-modified T-cells were detected within the TME via an RNAish assay. RESULTS: Responses across cohorts were affected by preconditioning and intra-tumoral NY-ESO-1 expression. Of the 42 patients reported (data cut-off 4June2018), 1 patient had a complete response, 14 patients had partial responses, 24 patients had stable disease, and 3 patients had progressive disease. The magnitude of gene-modified T-cell expansion shortly after infusion was associated with response in patients with high intra-tumoral NY-ESO-1 expression. Patients receiving a fludarabine-containing conditioning regimen experienced increases in serum IL-7 and IL-15. Prior to infusion, the TME exhibited minimal leukocyte infiltration; CD163+ tumor-associated macrophages (TAMs) were the dominant population. Modest increases in intra-tumoral leukocytes (≤5%) were observed in a subset of subjects at approximately 8 weeks. Beyond 8 weeks post infusion, the TME was minimally infiltrated with a TAM-dominant leukocyte infiltrate. Tumor-associated antigens and antigen presentation did not significantly change within the tumor post-T-cell infusion. Finally, NY-ESO-1 SPEAR T cells trafficked to the TME and maintained cytotoxicity in a subset of patients. CONCLUSIONS: Our studies elucidate some factors that underpin response and resistance to NY-ESO-1 SPEAR T-cell therapy. From these data, we conclude that a lymphodepletion regimen containing high doses of fludarabine and cyclophosphamide is necessary for SPEAR T-cell persistence and efficacy. Furthermore, these data demonstrate that non-T-cell inflamed tumors, which are resistant to PD-1/PD-L1 inhibitors, can be treated with adoptive T-cell based immunotherapy. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01343043 , Registered 27 April 2011.

Long-term safety and activity of NY-ESO-1 SPEAR T cells after autologous stem cell transplant for myeloma.

This study in patients with relapsed, refractory, or high-risk multiple myeloma (MM) evaluated the safety and activity of autologous T cells engineered to express an affinity-enhanced T-cell receptor (TCR) that recognizes a peptide shared by cancer antigens New York esophageal squamous cell carcinoma-1 (NY-ESO-1) and L-antigen family member 1 (LAGE-1) and presented by HLA-A*02:01. T cells collected from 25 HLA-A*02:01-positive patients with MM expressing NY-ESO-1 and/or LAGE-1 were activated, transduced with self-inactivating lentiviral vector encoding the NY-ESO-1c259TCR, and expanded in culture. After myeloablation and autologous stem cell transplant (ASCT), all 25 patients received an infusion of up to 1 × 1010 NY-ESO-1 specific peptide enhanced affinity receptor (SPEAR) T cells. Objective response rate (International Myeloma Working Group consensus criteria) was 80% at day 42 (95% confidence interval [CI], 0.59-0.93), 76% at day 100 (95% CI, 0.55-0.91), and 44% at 1 year (95% CI, 0.24-0.65). At year 1, 13/25 patients were disease progression-free (52%); 11 were responders (1 stringent complete response, 1 complete response, 8 very good partial response, 1 partial response). Three patients remained disease progression-free at 38.6, 59.2, and 60.6 months post-NY-ESO-1 SPEAR T-cell infusion. Median progression-free survival was 13.5 months (range, 3.2-60.6 months); median overall survival was 35.1 months (range, 6.4-66.7 months). Infusions were well tolerated; cytokine release syndrome was not reported. No fatal serious adverse events occurred during study conduct. NY-ESO-1 SPEAR T cells expanded in vivo, trafficked to bone marrow, demonstrated persistence, and exhibited tumor antigen-directed functionality. In this MM patient population, NY-ESO-1 SPEAR T-cell therapy in the context of ASCT was associated with antitumor activity. This trial was registered at www.clinicaltrials.gov as #NCT01352286.

Antitumor Activity Associated with Prolonged Persistence of Adoptively Transferred NY-ESO-1 c259T Cells in Synovial Sarcoma.

We evaluated the safety and activity of autologous T cells expressing NY-ESO-1c259, an affinity-enhanced T-cell receptor (TCR) recognizing an HLA-A2-restricted NY-ESO-1/LAGE1a-derived peptide, in patients with metastatic synovial sarcoma (NY-ESO-1c259T cells). Confirmed antitumor responses occurred in 50% of patients (6/12) and were characterized by tumor shrinkage over several months. Circulating NY-ESO-1c259T cells were present postinfusion in all patients and persisted for at least 6 months in all responders. Most of the infused NY-ESO-1c259T cells exhibited an effector memory phenotype following ex vivo expansion, but the persisting pools comprised largely central memory and stem-cell memory subsets, which remained polyfunctional and showed no evidence of T-cell exhaustion despite persistent tumor burdens. Next-generation sequencing of endogenous TCRs in CD8+ NY-ESO-1c259T cells revealed clonal diversity without contraction over time. These data suggest that regenerative pools of NY-ESO-1c259T cells produced a continuing supply of effector cells to mediate sustained, clinically meaningful antitumor effects.Significance: Metastatic synovial sarcoma is incurable with standard therapy. We employed engineered T cells targeting NY-ESO-1, and the data suggest that robust, self-regenerating pools of CD8+ NY-ESO-1c259T cells produce a continuing supply of effector cells over several months that mediate clinically meaningful antitumor effects despite prolonged exposure to antigen. Cancer Discov; 8(8); 944-57. ©2018 AACR.See related commentary by Keung and Tawbi, p. 914This article is highlighted in the In This Issue feature, p. 899.

A single dose of peripherally infused EGFRvIII-directed CAR T cells mediates antigen loss and induces adaptive resistance in patients with recurrent glioblastoma.

We conducted a first-in-human study of intravenous delivery of a single dose of autologous T cells redirected to the epidermal growth factor receptor variant III (EGFRvIII) mutation by a chimeric antigen receptor (CAR). We report our findings on the first 10 recurrent glioblastoma (GBM) patients treated. We found that manufacturing and infusion of CAR-modified T cell (CART)-EGFRvIII cells are feasible and safe, without evidence of off-tumor toxicity or cytokine release syndrome. One patient has had residual stable disease for over 18 months of follow-up. All patients demonstrated detectable transient expansion of CART-EGFRvIII cells in peripheral blood. Seven patients had post-CART-EGFRvIII surgical intervention, which allowed for tissue-specific analysis of CART-EGFRvIII trafficking to the tumor, phenotyping of tumor-infiltrating T cells and the tumor microenvironment in situ, and analysis of post-therapy EGFRvIII target antigen expression. Imaging findings after CART immunotherapy were complex to interpret, further reinforcing the need for pathologic sampling in infused patients. We found trafficking of CART-EGFRvIII cells to regions of active GBM, with antigen decrease in five of these seven patients. In situ evaluation of the tumor environment demonstrated increased and robust expression of inhibitory molecules and infiltration by regulatory T cells after CART-EGFRvIII infusion, compared to pre-CART-EGFRvIII infusion tumor specimens. Our initial experience with CAR T cells in recurrent GBM suggests that although intravenous infusion results in on-target activity in the brain, overcoming the adaptive changes in the local tumor microenvironment and addressing the antigen heterogeneity may improve the efficacy of EGFRvIII-directed strategies in GBM.

Heme oxygenase-1 gene promoter polymorphism is associated with the development of necrotizing acute pancreatitis.

OBJECTIVES: Acute pancreatitis is a severe and frequently life-threatening disease, which can lead to pancreatic necrosis, acute lung injury, systemic inflammatory response syndrome, and other complications. In this study, we hypothesized that the expression of heme oxygenase-1 determined by the number of guanidinium thiocyanate (GT) repeats can influence the occurrence of acute pancreatitis. METHODS: Patients with acute pancreatitis (n = 131) and age- and sex-matched healthy controls (n = 108) were studied. The polymerase chain reaction products were analyzed by ABI 3130 genetic analyzer and the exact size of the polymerase chain reaction products was determined by GeneMapper software. A short allele was defined as containing 27 GT repeats or fewer, whereas a long allele was more than 27 repeats. RESULTS: The subjects were categorized into 3 groups on the basis of the genotype results: 1 short and 1 long, 2 short, and 2 long alleles (L/L). Patients with necrotizing disease more frequently were carriers of LL genotype compared with those who had edematous acute pancreatitis. Furthermore, logistic regression analysis revealed that the presence of L/L allele type doubles the risk for developing pancreatic necrosis in patients with acute pancreatitis. CONCLUSIONS: The polymorphism of the GT repeats in the heme oxygenase-1 promoter region may be a risk factor for developing severe and necrotizing acute pancreatitis.

Characterization of the receptor binding residues of kisspeptins by positional scanning using peptide photoaffinity probes.

Kisspeptins, endogenous peptide ligands for GPR54, play an important role in GnRH secretion. Since in vivo administration of kisspeptins induces increased plasma LH levels, GPR54 agonists hold promise as therapeutic agents for the treatment of hormonal secretion diseases. To facilitate the design of novel potent GPR54 ligands, residues in kisspeptins that involve in the interaction with GPR54 were investigated by kisspeptin-based photoaffinity probes. Herein, we report the design and synthesis of novel kisspeptin-based photoaffinity probes, and the application to crosslinking experiments for GPR54-expressing cells.

MicroRNA profiling in lung cancer reveals new molecular markers for diagnosis.

OBJECTIVE: To identify new molecular diagnostic markers for non-small cell lung carcinoma (NSCLC) by analyzing microRNA (miRNA) expression profile differences in samples from NSCLC patients and adults with nonneoplastic diseases. STUDY DESIGN: miRNA expression was studied in archival formalin-fixed, paraffin-embedded tissues by microarray and confirmed by real-time PCR analysis of NSCLC and normal lung tissues. An algorithm for discriminating normal, squamous cell carcinoma (SQCC), and adenocarcinoma (ADC) tissue was derived from miRNA expression studies and applied towards characterization of poorly differentiated NSCLC samples. RESULTS: Microarray data from a genome-wide scan revealed 34 differentially expressed miRNAs, 5 of which enabled algorithmic discrimination of normal tissue from carcinoma (SQCC or ADC), as well as SQCC from ADC. Expression of miR-21 was significantly increased in both tumor types, whereas levels of miR-451 and miR-486-5p were reduced. SQCC was distinguished from normal tissue and ADC by high-level miR-205 expression and decreased miR-26b. Comparison of miRNA profiles to histological and immunohistochemical findings in 19 poorly differentiated specimens demonstrated the potential clinical utility of miRNA profiling to provide important insights into the classification of SQCC and ADC. CONCLUSION: This study presents a novel algorithm for specimen classification in cases of poorly differentiated NSCLC.

Paradoxical downregulation of CXC chemokine receptor 4 induced by polyphemusin II-derived antagonists.

CXC chemokine receptor 4 (CXCR4) is a G protein-coupled receptor implicated in cell entry of T-cell line-tropic HIV-1 strains. CXCR4 and its ligand stromal cell derived factor-1 (SDF-1)/CXCL12 play pivotal parts in many physiological processes and pathogenetic conditions (e.g., immune cell-homing and cancer metastasis). We previously developed the potent CXCR4 antagonist T140 from structure-activity relationship studies of the antimicrobial peptide polyphemusin II. T140 and its derivatives have been exploited in biological and biomedical studies for the SDF-1/CXCR4 axis. We investigated receptor localization upon ligand stimulation using fluorescent SDF-1 and T140 derivatives as well as a specific labeling technique for cellular-membrane CXCR4. Fluorescent T140 derivatives induced translocation of CXCR4 into the perinuclear region as observed by treatment with fluorescent SDF-1. T140 derivative-mediated internalization of CXCR4 was also monitored by the coiled-coil tag-probe system. These findings demonstrated that the CXCR4 antagonistic activity and anti-HIV activity of T140 derivatives were derived (at least in part) from antagonist-mediated receptor internalization.

The metastasis suppressor KISS1 lacks antimetastatic activity in the C8161.9 xenograft model of melanoma.

The objective of this study was to use the established xenograft model of human melanoma (C8161.9) to test a pharmacological approach to the effect of the metastasis suppressor KISS1. A KISS1 analog was used to inhibit the metastatic development of C8161.9 cells in nude mice. Further experiments were performed to test the validity of the C8161.9 model and test the connection between KISS1 expression and loss of metastatic potential. New clones of C8161.9 cells were obtained, with or without KISS1 expression, and were tested for metastasis formation. The absence of benefit in survival with the KISS1 analog compared with PBS prompted us to revisit the C8161.9 model. We found that the cells expressing KISS1, used in the previous study and obtained by transfection and single-cell cloning, were defective for both formation of orthotopic tumors and metastases. In mixing experiments, these cells could not suppress orthotopic tumor growth of KISS1-negative C8161.9 cells, suggesting that the suppression of metastasis by C8161.9-KISS1 cells may be intrinsic to the selected clone rather than related to KISS1 expression. Isolation of clones from parental C8161.9 cells in soft agar yielded cell populations that phenotypically and genotypically mimicked the KISS1-positive clone. In addition, new clones expressing KISS1 did not show any decrease in metastatic growth. These data demonstrate the heterogeneity of cell types in the C8161.9 cell line and the high risk of artifact linked to single-cell selection. A different xenograft model will be necessary to evaluate the use of KISS1 analogs as antimetastatic therapy.

Pan-histone deacetylase inhibitor panobinostat depletes CXCR4 levels and signaling and exerts synergistic antimyeloid activity in combination with CXCR4 antagonists.

Stromal cell derived factor-1 (SDF-1 or CXCL12) and its receptor CXCR4 are involved in the directional homing to the bone marrow niches and in peripheral mobilization of normal and transformed hematopoietic stem and myeloid progenitor cells. Elevated CXCR4 expression confers poor prognosis, whereas inhibition of CXCR4 signaling overcomes stroma-mediated chemoresistance in acute myeloid leukemia (AML). Here, we demonstrate that treatment with the pan-histone deacetylase inhibitor panobinostat (PS) depleted the mRNA and protein levels of CXCR4 in the cultured and primary AML cells. PS-induced acetylation of the heat shock protein (hsp) 90 reduced the chaperone association between CXCR4 and hsp90, directing CXCR4 to degradation by the 20S proteasome. PS treatment also depleted G protein-coupled receptor kinase 3, as well as attenuated the phosphorylation of AKT and ERK1/2 in AML cells, which was not affected by cotreatment with CXCL12. Compared with each agent alone, cotreatment with PS and CXCR4 antagonist AMD3100 or FC-131 synergistically induced apoptosis of cultured and primary AML cells. PS and FC-131 exerted more lethal effects on primary AML versus normal CD34(+) bone marrow progenitor cells. These findings support the rationale to test the in vivo efficacy of PS in enhancing the lethal effects of CXCR4 antagonists against AML cells.

Activation of Rho and Rho-associated kinase by GPR54 and KiSS1 metastasis suppressor gene product induces changes of cell morphology and contributes to apoptosis.

The mechanism of action of the metastasis suppressor KiSS1 and its receptor GPR54 is still incompletely characterized. Although the loss of KiSS1 expression by tumor cells has been associated with a metastatic phenotype, the nature of the cellular target of the secreted kisspeptins is unknown. Although an autocrine model of action has been generally assumed, metastasis suppression by KiSS1 has also been shown in cells that do not express GPR54, suggesting a paracrine mechanism in which kisspeptins affect cells in the metastatic niche. Activation of GPR54 was shown to inhibit cell motility and invasion of tumor cells, induce the formation of stress fibers, and reduce the expression of matrix metalloproteinase 9. We showed previously that the activation of GPR54 by kisspeptin-10 suppressed CXCR4-mediated chemotaxis in response to stromal cell-derived factor 1/CXCL12 and abolished the phosphorylation of Akt by CXCR4. We also demonstrated that activation of GPR54 inhibited Akt phosphorylation after the activation of epidermal growth factor receptor and the insulin receptor and triggered apoptosis in epithelial and lymphoid cell lines through a mechanism involving extracellular signal-regulated kinase (ERK) mitogen-activated protein kinase. We show here that the activation of GPR54 induced immediate and profound changes of cell morphology, including cytoplasmic condensation and formation of unpolarized plasma membrane protrusions. These events were dependent on Rho and Rho-Associated Kinase (ROCK) activation. The activation of ROCK also contributed to GPR54-mediated apoptosis in 293 cells, and its effect was additive to and independent of ERK activation. These results suggest that RhoA and ROCK are additional key components of the antimetastatic effect of kisspeptins.

KiSS1 metastasis suppressor gene product induces suppression of tyrosine kinase receptor signaling to Akt, tumor necrosis factor family ligand expression, and apoptosis.

The powerful metastasis suppressor function of KiSS1 gene products has been demonstrated in both clinical studies and experimental models, but its mechanism is still incompletely understood. Studies on the antimetastatic function of KiSS1 and GPR54 largely focused on the autocrine inhibition of cell motility, despite experimental evidence of an alternative post-migratory effect. We showed previously that the activation of its cognate receptor GPR54 by kisspeptin-10 suppressed the capacity of the prometastatic chemokine receptor CXCR4 to induce chemotaxis in response to stromal cell derived factor 1 and abolished the activation of Akt by CXCR4. We demonstrate here that activation of GPR54 can also abolish the activation of Akt by the tyrosine kinase receptors for epidermal growth factor and insulin. The signaling of GPR54 was sufficient to trigger apoptosis in epithelial and lymphoid cell lines. Surprisingly, this phenomenon depended largely on the activation of extracellular signal-regulated kinase (ERK) rather than the inhibition of Akt. Activation of GPR54 resulted in the ERK-dependent expression of tumor necrosis factor-alpha and FasL in a lymphoid cell line, the latter being the main trigger of apoptosis. These data provide novel mechanisms relevant to a potential autocrine metastasis suppression effect of KiSS1 on GPR54-positive tumor cells. More importantly, they also establish an experimental basis for a paracrine mode of action by which kisspeptins suppress the metastatic potential of tumor cells lacking expression of the receptor, as observed in several animal models of metastasis. The action on stromal cells significantly broadens the clinical relevance of this metastasis suppressor.

Physical association of GPR54 C-terminal with protein phosphatase 2A.

KiSS1 was discovered as a metastasis suppressor gene and subsequently found to encode kisspeptins (KP), ligands for a G protein coupled receptor (GPCR), GPR54. This ligand-receptor pair was later shown to play a critical role in the neuro-endocrine regulation of puberty. The C-terminal cytoplasmic (C-ter) domain of GPR54 contains a segment rich in proline and arginine residues that corresponds to the primary structure of four overlapping SH3 binding motifs. Yeast two hybrid experiments identified the catalytic subunit of protein phosphatase 2A (PP2A-C) as an interacting protein. Pull-down experiments with GST fusion proteins containing the GPR54 C-ter confirmed binding to PP2A-C in cell lysates and these complexes contained phosphatase activity. The proline arginine rich segment is necessary for these interactions. The GPR54 C-ter bound directly to purified recombinant PP2A-C, indicating the GPR54 C-ter may form complexes involving the catalytic subunit of PP2A that regulate phosphorylation of critical signaling intermediates.

Heat shock response in CHO mammalian cells is controlled by a nonlinear stochastic process.

In many biological systems, the interactions that describe the coupling between different units in a genetic network are nonlinear and stochastic. We study the interplay between stochasticity and nonlinearity using the responses of Chinese hamster ovary (CHO) mammalian cells to different temperature shocks. The experimental data show that the mean value response of a cell population can be described by a mathematical expression (empirical law) which is valid for a large range of heat shock conditions. A nonlinear stochastic theoretical model was developed that explains the empirical law for the mean response. Moreover, the theoretical model predicts a specific biological probability distribution of responses for a cell population. The prediction was experimentally confirmed by measurements at the single-cell level. The computational approach can be used to study other nonlinear stochastic biological phenomena.

Association of nucleophosmin negatively regulates CXCR4-mediated G protein activation and chemotaxis.

CXCR4, the primary receptor for CXCL12, plays a critical role in the development of hematopoietic, vascular, central nervous, and immune systems by mediating directional migration of precursor cells. This mechanism promotes homing of tumor cells to metastatic sites that secrete CXCL12, and CXCR4 expression is a negative prognostic factor in acute myelogenous leukemia (AML). To elucidate mechanisms that regulate CXCR4 signaling, we used a proteomic approach to identify proteins physically associated with CXCR4. Analysis of CXCR4 immune complexes identified nucleophosmin (NPM), which was confirmed by reciprocal coimmunoprecipitation for NPM. Constitutively active CXCR4 variants bound higher levels of NPM than the wild-type receptor, which was reversed by T140, an inverse agonist. NPM binding to CXCR4 localized interactions to the C terminus and cytoplasmic loop (CL)-3, but not CL-1 or CL-2. Alanine scanning mutagenesis demonstrated that positively charged amino acids in CL-3 were critical for NPM binding. Recombinant NPM decreased GTP binding in membrane fractions after activation of CXCR4 by CXCL12. Suppression of NPM expression enhanced chemotactic responses to CXCL12, and, conversely, overexpression of a cytosolic NPM mutant reduced chemotaxis induced by CXCL12. This study provides evidence for a novel role for NPM as a negative regulator of CXCR4 signaling induced by CXCL12 that may be relevant to the biology of AML.

SAR and QSAR studies on the N-terminally acylated pentapeptide agonists for GPR54.

Kisspeptins (KPs) play important roles in the regulation of physiological and pathological states through activation of the cognate receptor GPR54. Our previous studies to downsize KP agonists to the essential GPR54 pharmacophore identified peptides 1-3 as low molecular weight GPR54 agonists. In this study, the effect of N-terminal acyl groups on the activity of a series of analogues (R-Phe-Gly-Leu-Arg-Trp-NH2) was investigated in order to develop novel potent GPR54 agonists. Among the compounds developed, the most potent agonistic activity for GPR54 was observed for N-terminal 4-fluorobenzoyl analogue 29. Using quantitative structure-activity relationship studies, it was demonstrated that the inductively negative and small substituents were preferred at the 4-position of N-terminal benzoyl groups.