Academic literature on the topic 'SUPER AGONIST'

The human CC chemokine receptor 5 (CCR5) is a G protein–coupled receptor (GPCR) that plays a major role in inflammation and is involved in cancer, HIV, and COVID-19. Despite its importance as a drug target, the molecular activation mechanism of CCR5, i.e., how chemokine agonists transduce the activation signal through the receptor, is yet unknown. Here, we report the cryo-EM structure of wild-type CCR5 in an active conformation bound to the chemokine super-agonist [6P4]CCL5 and the heterotrimeric Gi protein. The structure provides the rationale for the sequence-activity relation of agonist and antagonist chemokines. The N terminus of agonist chemokines pushes onto specific structural motifs at the bottom of the orthosteric pocket that activate the canonical GPCR microswitch network. This activation mechanism differs substantially from other CC chemokine receptors that bind chemokines with shorter N termini in a shallow binding mode involving unique sequence signatures and a specialized activation mechanism.

G-protein coupled receptors (GPCRs) are known to form homo- and hetero- oligomers which are considered critical to modulate their function. However, studying the existence and functional implication of these complexes is not straightforward as controversial results are obtained depending on the method of analysis employed. Here, we use a quantitative single molecule super-resolution imaging technique named qPAINT to quantify complex formation within an example GPCR. qPAINT, based upon DNA-PAINT, takes advantage of the binding kinetics between fluorescently labelled DNA imager strands to complementary DNA docking strands coupled to protein targeting antibodies to quantify the protein copy number in nanoscale dimensions. We demonstrate qPAINT analysis via a novel pipeline to study the oligomerization of the purinergic receptor Y2 (P2Y2), a rhodopsin-like GPCR, highly expressed in the pancreatic cancer cell line AsPC-1, under control, agonistic and antagonistic conditions. Results reveal that whilst the density of P2Y2 receptors remained unchanged, antagonistic conditions displayed reduced percentage of oligomers, and smaller numbers of receptors in complexes. Yet, the oligomeric state of the receptors was not affected by agonist treatment, in line with previous reports. Understanding P2Y2 oligomerization under agonistic and antagonistic conditions will contribute to unravelling P2Y2 mechanistic action and therapeutic targeting.

Abstract Adoptive cell transfer of antigen specific T cells represents a major advance in cancer immunotherapy, with robust clinical outcomes in a subset of patients. To achieve effective responses, both the number of transferred T cells and their cell differentiation state are critical determinants. T cells can be expanded with T cell receptor (TCR)-mediated stimulation and IL-2 but this can also lead to T cell differentiation into effector T cells, resulting in diminished therapeutic efficacy, whereas maintenance of a more stem-like prior to adoptive transfer is beneficial. Here, we show that an engineered IL-2 partial agonist generated on the super-IL-2 background promoted T-cell expansion without driving terminal differentiation. The partial agonist exhibited altered signaling and mediated distinctive downstream transcriptional, epigenetic, and metabolic programs. Moreover, it sustained expression of transcription factor TCF-1 (T cell transcription factor 1) and promoted mitochondrial fitness, facilitating the maintenance of a stem cell-like state. Accordingly, TCR transgenic and CAR-modified CD8+ T cells expanded with this engineered molecule displayed robust anti-tumor activity in vivo in established models of melanoma and acute lymphoblastic leukemia. Thus, tempering cytokine signaling with the IL-2 partial agonist provides a strategy for enhancing therapeutic efficacy by limiting exhaustion while preserving stemness. Moreover, our findings demonstrate the distinctive power of generation cytokine partial agonists with distinctive activities.

183 Background: It was reported that GnRH antagonist could extend progression free survival for prostate cancer patients significantly longer than GnRH agonist in a first line hormonal therapy. However, the usefulness of switching from GnRH agonist to GnRH antagonist as a second hormonal therapy remains obscure. We performed a multicentral prospective study to investigate whether the switching from GnRH agonist to GnRH antagonist (degalerix) for patients with castration resistant prostate cancer (CRPC) as the 2nd line hormonal therapy was effective. Methods: 37 patients who were pathologically diagnosed as prostatic adenocarcinoma and developed CRPC after 1st line hormonal therapy with GnRH agonist plus anti-androgens were enrolled. After confirming anti-androgen withdrawal syndrome, they were treated with switching from GnRH agonists to degalerix. The primary endpoint was PSA response (PSA decline or up to 10% over baseline PSA). Secondary endpoints were the time to 25% PSA increase from the baseline (PSA response time), PSA progression free survival (PPFS), the time to treatment failure, cancer specific survival, radiographic PFS (rPFS), and safety. Results: Mean age was 76 years old, super high risk; 20 cases (54.1%), high risk; 11 cases (29.7%), intermediate risk; 5 cases (13.5%), low risk; one case (2.7%). PSA responder rate was 24.3% (9 cases). In responders, the median PSA response time was 5.75 months, the median PPFS was 1.77 months, and rPFS rate at 3 months was 96%. Regarding safety, only 2 cases (5.4%) showed G3 of AE. The PSA response had no relationship with the change of serum testosterone, LH nor FSH. Conclusions: The effectiveness of switching from GnRH agonist to GnRH antagonist showed to be limited. Although no predictive factor of the switching was recognized, some long-term responders were seen. We expect the possibility of switching to GnRH antagonist for patients in the early stage of CRPC, especially non-metastatic status. Clinical trial information: UNKNOWN.

Abstract Introduction: Combination studies with engineered IL-2 variants and immune-checkpoint blockade have demonstrated synergy in both pre-clinical models and the clinic. Co-administration of those 2 agents can potentially face challenges related to overlapping toxicities in obtaining optimal doses for synergistic effects. We propose to potentiate the synergy by enabling cis activation of IL-2 agonism and blockade of PD-1/PDL-2 binding with a single anti-PD1-IL2 to generate Bifunctional SuperKines for ImmunoTherapy (BiSKIT). Both human (h) and mouse (m) versions of anti-PD1 are fused with MDNA109FEAA, an IL-2 superkine with enhanced affinity for IL-2Rβ (CD122) and no binding to IL-2Rα (CD25). Experimental Procedure: Studies included binding analyses with Biacore/SPR, signaling analyses in an IL-2 cell reporter assay, cell proliferation assay, in vitro pSTAT5 signaling in human PBMCs, PD1/PDL-1 cell reporter assay and efficacy in syngeneic tumor models. Summary of Data: Anti-hPD1-MDNA109FEAA and surrogate anti-mPD1-MDNA109FEAA were tested in both in vitro and in vivo assays. Both constructs demonstrated selective binding to either hPD1 or mPD1 as expected, and the MDNA109FEAA motif retained its receptor selectivity (enhanced affinity to CD122 and no binding to CD25). In both HEK-Blue IL-2 reporter and CTLL-2 proliferation bioassays, anti-PD1-MDNA109FEAA exhibited similar agonistic effect as MDNA109FEAA-Fc, demonstrating that potency towards the IL-2 axis was not diminished. This was further confirmed with pSTAT5 signaling in primary human PBMCs where anti-PD1-MDNA109FEAA showed enhanced activation of CD8 T-cells and NK cells with reduced activity on Treg when compared to rhIL-2. Both constructs were also effective at inhibiting PD1/PDL-1 pathway in respective human and mouse specific cell-based reporter assays. In a CT26 syngeneic colon tumor model, anti-mPD1-MDNA109FEAA exhibited superior efficacy over monotherapy and combination with anti-mPD1 and MDNA109FEAA-Fc when administered at equal molar dosage and same schedule. Conclusion: We have engineered anti-PD1-MDNA109FEAA to enable cis engagement with IL-2 receptor and PD1 as an approach to activate immune cells while reducing their exhaustion. Anti-mPD1-MDNA109FEAA achieved potent efficacy in a CT26 colon tumor model and is currently being evaluated in additional syngeneic tumor models with varying responsiveness to immune checkpoint blockade. Citation Format: Minh D. To, Manjunatha Ankathatti Munegowda, Rosemina Merchant, Aanchal Sharma. An ‘anti-PD1-IL2 beta-only super-agonist’ displays potent anti-tumor efficacy [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 5532.

αMSH has generally been accepted as the endogenous ligand for melanocortin 4 receptor (MC4R), which plays a major role in energy homeostasis. Targeting MC4R to develop antiobesity agents, many investigators have performed a structure-activity relationship (SAR) studies based on αMSH structure. In this report, we performed a SAR study using human βMSH (5–22 ) (DEGPYRMEHFRWGSPPKD, peptide 1) as a lead sequence to develop potent and selective agonists for MC4R and MC3R. The SAR study was begun with a truncation of N terminus of βMSH (5–22 ) together with acetylation of the N terminus and amidation of the C terminus of the peptide. Introduction of a cyclic disulfide constrain and replacement of L-Phe with D-Phe afforded a super potent agonist (peptide 5). Furthermore truncation at the C terminus generated a small and potent MC4R and MC3R agonist (Ac-YRcyclo[CEHdFRWC]amide, peptide 6), which exhibited no MC5R and greatly reduced MC1R activity. Molecular modeling of Ac-YRcyclo[CEHdFRWC]amide (peptide 6) revealed that Arg2 in the peptide formed a salt bridge with Glu4. Subcutaneous or intracerebroventricular administration of peptide 6 in rats showed potent in vivo efficacy as evidenced by its effects in reducing energy balance, increasing fat use, and decreasing weight gain in both acute and chronic rat metabolic studies. Furthermore, the antiobesity effect by peptide 6 was manifested only in wild-type but not MC4R-deficient mice, indicating that antiobesity effects of the peptide were attributed largely through MC4R but not MC3R agonist activity of the peptide.

e23079 Background: Abstract: CD137 (4-1BB), a member of the TNFR super family, is expressed on several subsets of activated immune cells and acts as co-stimulatory receptor for T-cells to promote cellular proliferation, survival and cytokine production. Agonist antibodies against human CD137 in early clinical trials show strikingly different toxicology profiles, ranging from severe liver toxicity at low doses, to manageable adverse effects at modest doses. Whereas preclinical studies in mouse show intense liver T-cell infiltration and toxicity by surrogate agonist mAb. The preclinical efficacy and pharmacology of anti-CD137 were extensively tested and validated in various tumor models with intact immune system. Since none of the available anti-CD137 agonist antibodies display multiple species cross reactivity including rodent, the translational significance of these mAbs is limited concerning their efficacy and safety profile. Methods: Through our proprietary Dynamic Precision Library (DPL) technology, we have discovered multiple agonistic antibodies that exhibit high affinity and broad species cross-reactivity against a unique epitope shared among human, monkey and rodent CD137. Results: These mAbs, after crosslinking, strongly activate CD137 mediated cellular NFkB signaling, as well as stimulate T-cell proliferation and IFNg release in the presence of suboptimal concentrations of anti-CD3 antibodies. The broad species cross-reactivity by a single therapeutic agent enabled us to evaluate their potentiation of host immune responses that gives rise to the anti-tumor efficacy and potential toxicity in relevant rodent and monkey models. Our lead anti-CD137 agonist mAb has demonstrated robust anti-tumor activities in multiple mouse syngeneic tumor models, with durable antigen specific protective memory T-cell responses. Conclusions: In sharp contrast to surrogate anti-mouse CD137 mAbs, no toxicities including liver inflammation or other adverse effects were observed. These preclinical results warrant further clinical development of our lead as a novel immunotherapeutic anti-cancer agent.

Abstract In response to changing external signal strength, innate monocytes may be dynamically programmed into distinct functional states, which may bear significance relevance in host pathophysiology. However, molecular mechanisms that control innate memory dynamics are not well understood nor extensively studied. Using lipopolysaccharide (LPS), the model stimulant of Toll-Like-Receptor 4 (TLR4), we observed that the expressions of pro-inflammatory mediators are preferentially sustained in monocytes adapted by subclinical super-lower dose LPS, and suppressed/tolerized in monocytes programmed by higher dosages of LPS. These phenomena are well conserved in both mice and human monocytes. At the molecular level, we observed that monocytes programmed by super-low dose LPS maintain higher levels of transcription factor IRF5. We also observed that the inflammatory monocyte programming is dependent upon TRAM/TRIF but not MyD88. Similar to LPS, we also observed biphasic inflammatory adaptation and tolerance in monocytes challenged with varying dosages of TLR7 agonist. In sharp contrast, rising doses of TLR3 agonist preferentially caused inflammatory adaptation without inducing tolerance. At the functional level, we observed that in vivo programming of monocytes by subclinical dose LPS exacerbates the progression of atherosclerosis. Taken together, our study provides novel mechanisms for the dynamic programming/memory of innate monocytes and their pathological implications in atherosclerosis.