Non-canonical modulators of nuclear receptors

Discovery of novel 6-(piperidin-1-ylsulfonyl)-2H-chromenes targeting α-glucosidase, α-amylase, and PPAR-γ: Design, synthesis, virtual screening, and anti-diabetic activity for type 2 diabetes mellitus

A new series of 2H-chromene-based sulfonamide derivatives 3-12 has been synthesized and characterized using different spectroscopic techniques. The synthesized 2H-chromenes were synthesized by reacting activated methylene with 5-(piperidin-1-ylsulfonyl)salicylaldehyde through one-step condensation followed by intramolecular cyclization. Virtual screening of the designed molecules on α-glucosidase enzymes (PDB: 3W37 and 3A4A) exhibited good binding affinity suggesting that these derivatives may be potential α-glucosidase inhibitors. In-vitro α-glucosidase activity was conducted firstly at 100 µg/mL, and the results demonstrated good inhibitory potency with values ranging from 90.6% to 96.3% compared to IP = 95.8% for Acarbose. Furthermore, the IC50 values were determined, and the designed derivatives exhibited inhibitory potency less than 11 µg/mL. Surprisingly, two chromene derivatives 6 and 10 showed the highest potency with IC50 values of 0.975 ± 0.04 and 0.584 ± 0.02 µg/mL, respectively, compared to Acarbose (IC50 = 0.805 ± 0.03 µg/mL). Moreover, our work was extended to evaluate the in-vitro α-amylase and PPAR-γ activity as additional targets for diabetic activity. The results exhibited moderate activity on α-amylase and potency as PPAR-γ agonist making it a multiplet antidiabetic target. The most active 2H-chromenes 6 and 10 exhibited significant activity to PPAR-γ with IC50 values of 3.453 ± 0.14 and 4.653 ± 0.04 µg/mL compared to Pioglitazone (IC50 = 4.884±0.29 µg/mL) indicating that these derivatives improve insulin sensitivity by stimulating the production of small insulin-sensitive adipocytes. In-silico ADME profile analysis indicated compliance with Lipinski's and Veber's rules with excellent oral bioavailability properties. Finally, the docking simulation was conducted to explain the expected binding mode and binding affinity.

Molecular basis and dual ligand regulation of tetrameric Estrogen Receptor α/14-3-3ζ protein complex

Therapeutic strategies targeting Nuclear Receptors (NRs) beyond their endogenous ligand binding pocket have gained significant scientific interest, driven by a need to circumvent problems associated with drug resistance and pharmacological profile. The hub protein 14-3-3 is an endogenous regulator of various NRs, providing a novel entry point for small molecule modulation of NR activity. Exemplified, 14-3-3 binding to the C-terminal F-domain of the Estrogen Receptor alpha (ERα), and small molecule stabilization of the ERα/14-3-3ζ protein complex by the natural product Fusicoccin A (FC-A), was demonstrated to downregulate ERα-mediated breast cancer proliferation. This presents a novel drug discovery approach to target ERα, however, structural and mechanistic insights into ERα/14-3-3 complex formation are lacking. Here, we provide an in-depth molecular understanding of the ERα/14-3-3ζ complex by isolating 14-3-3ζ in complex with an ERα protein construct comprising its Ligand Binding Domain (LBD) and phosphorylated F-domain. Bacterial co-expression and co-purification of the ERα/14-3-3ζ complex, followed by extensive biophysical and structural characterization, revealed a tetrameric complex between the ERα homodimer and the 14-3-3ζ homodimer. 14-3-3ζ binding to ERα, and ERα/14-3-3ζ complex stabilization by FC-A, appeared to be orthogonal to ERα endogenous agonist (E2) binding, E2-induced conformational changes, and cofactor recruitment. Similarly, the ERα antagonist 4-hydroxytamoxifen inhibited cofactor recruitment to the ERα LBD while ERα was bound to 14-3-3ζ. Furthermore, stabilization of the ERα/14-3-3ζ protein complex by FC-A was not influenced by the disease-associated and 4-hydroxytamoxifen resistant ERα-Y537S mutant. Together, these molecular and mechanistic insights provide direction for targeting ERα via the ERα/14-3-3 complex as an alternative drug discovery approach.

Recent applications of computational methods to allosteric drug discovery

Interest in exploiting allosteric sites for the development of new therapeutics has grown considerably over the last two decades. The chief driving force behind the interest in allostery for drug discovery stems from the fact that in comparison to orthosteric sites, allosteric sites are less conserved across a protein family, thereby offering greater opportunity for selectivity and ultimately tolerability. While there is significant overlap between structure-based drug design for orthosteric and allosteric sites, allosteric sites offer additional challenges mostly involving the need to better understand protein flexibility and its relationship to protein function. Here we examine the extent to which structure-based drug design is impacting allosteric drug design by highlighting several targets across a variety of target classes.

Bisphenol A derivatives act as novel coactivator-binding inhibitors for estrogen receptor β

Bisphenol A and its derivatives are recognized as endocrine disruptors based on their complex effects on estrogen receptor (ER) signaling. While the effects of bisphenol derivatives on ERα have been thoroughly evaluated, how these chemicals affect ERβ signaling is less well understood. Herein, we sought to identify novel ERβ ligands using a radioligand competitive binding assay to screen a chemical library of bisphenol derivatives. Many of the compounds identified showed intriguing dual activities as both ERα agonists and ERβ antagonists. Docking simulations of these compounds and ERβ suggested that they bound not only to the canonical binding site of ERβ but also to the coactivator binding site located on the surface of the receptor, suggesting that they act as coactivator-binding inhibitors (CBIs). Receptor-ligand binding experiments using WT and mutated ERβ support the presence of a second ligand-interaction position at the coactivator-binding site in ERβ, and direct binding experiments of ERβ and a coactivator peptide confirmed that these compounds act as CBIs. Our study is the first to propose that bisphenol derivatives act as CBIs, presenting critical insight for the future development of ER signaling-based drugs and their potential to function as endocrine disruptors.

Identification and Functional Characterization of a Novel Androgen Receptor Coregulator, EAP1

The androgen receptor (AR) plays an essential role in the development of prostate cancer, and androgen-deprivation therapy is used as a first-line treatment for prostate cancer. However, under androgen-deprivation therapy, castration-resistant prostate cancer inevitably arises, suggesting that the interacting transcriptional coregulators of AR are promising targets for developing novel therapeutics. In this study, we used novel proteomic techniques to evaluate the AR interactome, including biochemically labile binding proteins, which might go undetected by conventional purification methods. Using rapid immunoprecipitation mass spectrometry of endogenous proteins, we identified enhanced at puberty 1 (EAP1) as a novel AR coregulator, whereas its interaction with AR could not be detected under standard biochemical conditions. EAP1 enhanced the transcriptional activity of AR via the E3 ubiquitin ligase activity, and its ubiquitination substrate proteins included AR and HDAC1. Furthermore, in prostate cancer specimens, EAP1 expression was significantly correlated with AR expression as well as a poor prognosis of prostate cancer. Together, these results suggest that EAP1 is a novel AR coregulator that promotes AR activity and potentially plays a role in prostate cancer progression.

Structure-Activity Relationship Studies of Trisubstituted Isoxazoles as Selective Allosteric Ligands for the Retinoic-Acid-Receptor-Related Orphan Receptor γt

The inhibition of the nuclear receptor retinoic-acid-receptor-related orphan receptor γt (RORγt) is a promising strategy in the treatment of autoimmune diseases. RORγt features an allosteric binding site within its ligand-binding domain that provides an opportunity to overcome drawbacks associated with orthosteric modulators. Recently, trisubstituted isoxazoles were identified as a novel class of allosteric RORγt inverse agonists. This chemotype offers new opportunities for optimization into selective and efficacious allosteric drug-like molecules. Here, we explore the structure–activity relationship profile of the isoxazole series utilizing a combination of structure-based design, X-ray crystallography, and biochemical assays. The initial lead isoxazole (FM26) was optimized, resulting in compounds with a ∼10-fold increase in potency (low nM), significant cellular activity, promising pharmacokinetic properties, and a good selectivity profile over the peroxisome-proliferated-activated receptor γ and the farnesoid X receptor. We envisage that this work will serve as a platform for the accelerated development of isoxazoles and other novel chemotypes for the effective allosteric targeting of RORγt.

Orthosteric and Allosteric Dual Targeting of the Nuclear Receptor RORγt with a Bitopic Ligand

The RORγt nuclear receptor (NR) is of critical importance for the differentiation and proliferation of T helper 17 (Th17) cells and their production of the pro-inflammatory cytokine IL-17a. Dysregulation of RORγt has been linked to various autoimmune diseases, and small molecule inhibition of RORγt is therefore an attractive strategy to treat these diseases. RORγt is a unique NR in that it contains both a canonical, orthosteric and a second, allosteric ligand binding site in its ligand binding domain (LBD). Hence, dual targeting of both binding pockets constitutes an attractive alternative molecular entry for pharmacological modulation. Here, we report a chemical biology approach to develop a bitopic ligand for the RORγt NR, enabling concomitant engagement of both binding pockets. Three candidate bitopic ligands, Bit-L15, Bit-L9, and Bit-L4, comprising an orthosteric and allosteric RORγt pharmacophore linked via a polyethylene glycol (PEG) linker, were designed, synthesized, and evaluated to examine the influence of linker length on the RORγt binding mode. Bit-L15 and Bit-L9 show convincing evidence of concomitant engagement of both RORγt binding pockets, while the shorter Bit-L4 does not show this evidence, as was anticipated during the ligand design. As the most potent bitopic RORγt ligand, Bit-L15, antagonizes RORγt function in a potent manner in both a biochemical and cellular context. Furthermore, Bit-L15 displays an increased selectivity for RORγt over RORα and PPARγ compared to the purely orthosteric and allosteric parent compounds. Combined, these results highlight potential advantages of bitopic NR modulation over monovalent targeting strategies.

Delineation of the molecular determinants of the unique allosteric binding site of the orphan nuclear receptor RORγt

Nuclear receptors (NRs) are high-interest targets in drug discovery because of their involvement in numerous biological processes and diseases. Classically, NRs are targeted via their hydrophobic, orthosteric pocket. Although successful, this approach comes with challenges, including off-target effects due to lack of selectivity. Allosteric modulation of NR activity constitutes a promising pharmacological strategy. The retinoic acid receptor-related orphan receptor-γt (RORγt) is a constitutively active NR that positively regulates the expression of interleukin-17 in T helper 17 cells. Inhibiting this process is an emerging strategy for managing autoimmune diseases. Recently, an allosteric binding pocket in the C-terminal region of the ligand-binding domain (LBD) of RORγt was discovered that is amenable to small-molecule drug discovery. Compounds binding this pocket induce a reorientation of helix 12, thereby preventing coactivator recruitment. Therefore, inverse agonists binding this site with high affinity are actively being pursued. To elucidate the pocket formation mechanism, verify the uniqueness of this pocket, and substantiate the relevance of targeting this site, here we identified the key characteristics of the RORγt allosteric region. We evaluated the effects of substitutions in the LBD on coactivator, orthosteric, and allosteric ligand binding. We found that two molecular elements unique to RORγt, the length of helix 11' and a Gln-487 residue, are crucial for the formation of the allosteric pocket. The unique combination of elements present in RORγt suggests a high potential for subtype-selective targeting of this NR to more effectively treat patients with autoimmune diseases.

A tiered high-throughput screening approach for evaluation of estrogen and androgen receptor modulation by environmentally relevant bisphenol A substitutes

Bisphenol A (BPA) is a high production volume chemical with a broad application spectrum. As an endocrine disrupting chemical, mainly by modulation of nuclear receptors (NRs), BPA has an adverse impact on organisms and is identified as a substance of very high concern under the European REACH regulation. Various BPA substitution candidates have been developed in recent years, however, information concerning the endocrine disrupting potential of these substances is still incomplete or missing. In this study, we intended to investigate the endocrine potential of BPA substitution candidates used in environmentally relevant applications such as thermal paper or epoxy resins. Based on an extensive literature and patent search, 33 environmentally relevant BPA substitution candidates were identified. In order to evaluate the endocrine potential of the BPA replacements, a screening cascade consisting of biochemical and cell-based assays was employed to investigate substance binding to the NRs estrogen receptor α and β, as well as androgen receptor, co-activator recruitment and NR-mediated reporter gene activation. In addition, a computational docking approach for retrospective prediction of receptor binding was carried out. Our results show that some BPA substitution candidates, for which so far no or only very few data were available, possess a substantial endocrine disrupting potential (TDP, BPZ), while several substances (BPS, D-8, DD70, DMP-OH, TBSA, D4, CBDO, ISO, VITC, DPA, and DOPO) did not reveal any NR binding.

Elucidation of an Allosteric Mode of Action for a Thienopyrazole RORγt Inverse Agonist

The demand for allosteric targeting of nuclear receptors is high, but examples are limited, and structural information is scarce. The retinoic acid-related orphan receptor gamma t (RORγt) is an important transcriptional regulator for the differentiation of T helper 17 cells for which the first, and some of the most promising, examples of allosteric nuclear receptor modulation have been reported and structurally proven. In a 2015 patent, filed by the pharmaceutical company Glenmark, a new class of small molecules was reported that act as potent inverse agonists for RORγt. A compound library around the central thienopyrazole scaffold captured a clear structure-activity relationship, but the binding mechanism of this new class of RORγt modulators has not been elucidated. Using a combination of biochemical and X-ray crystallography studies, here the allosteric mechanism for the inverse agonism for the most potent compound, classified in the patent as "example 13", is reported, providing a strongly desired additional example of allosteric nuclear receptor targeting.

Ligand-Based Design of Allosteric Retinoic Acid Receptor-Related Orphan Receptor γt (RORγt) Inverse Agonists

Retinoic acid receptor-related orphan receptor γt (RORγt) is a nuclear receptor associated with the pathogenesis of autoimmune diseases. Allosteric inhibition of RORγt is conceptually new, unique for this specific nuclear receptor, and offers advantages over traditional orthosteric inhibition. Here, we report a highly efficient in silico-guided approach that led to the discovery of novel allosteric RORγt inverse agonists with a distinct isoxazole chemotype. The the most potent compound, 25 (FM26), displayed submicromolar inhibition in a coactivator recruitment assay and effectively reduced IL-17a mRNA production in EL4 cells, a marker of RORγt activity. The projected allosteric mode of action of 25 was confirmed by biochemical experiments and cocrystallization with the RORγt ligand binding domain. The isoxazole compounds have promising pharmacokinetic properties comparable to other allosteric ligands but with a more diverse chemotype. The efficient ligand-based design approach adopted demonstrates its versatility in generating chemical diversity for allosteric targeting of RORγt.

Steroid receptor/coactivator binding inhibitors: An update

The purpose of this review is to highlight recent developments in small molecules and peptides that block the binding of coactivators to steroid receptors. These coactivator binding inhibitors bind at the coregulator binding groove, also known as Activation Function-2, rather than at the ligand-binding site of steroid receptors. Steroid receptors that have been targeted with coactivator binding inhibitors include the androgen receptor, estrogen receptor and progesterone receptor. Coactivator binding inhibitors may be useful in some cases of resistance to currently prescribed therapeutics. The scope of the review includes small-molecule and peptide coactivator binding inhibitors for steroid receptors, with a particular focus on recent compounds that have been assayed in cell-based models.

Sulindac-derived retinoid X receptor-α modulator attenuates atherosclerotic plaque progression and destabilization in ApoE-/- mice

BACKGROUND AND PURPOSE

Atherosclerosis is a chronic inflammatory disease, and retinoid X receptor-α (RXRα) is an intriguing anti-atherosclerosis target. This study investigated whether and how an RXRα modulator, K-80003, derived from a non-steroidal anti-inflammatory drug attenuates atherosclerotic plaque progression and destabilization.

EXPERIMENTAL APPROACH

Our previously established ApoE-/- mouse model of carotid vulnerable plaque progression was treated with K-80003 or vehicle for 4 or 8 weeks. Samples of carotid arteries and serum were collected to determine atherosclerotic lesion size, histological features, expression of related proteins, and lipid profiles. In vitro studies were carried out in 7-ketocholesterol (7-KC)-stimulated macrophages treated with or without K-80003.

KEY RESULTS

K-80003 significantly reduced lesion size, plaque rupture, macrophage infiltration, and inflammatory cytokine levels. Plaque macrophages positive for nuclear p65 (RelA) NF-κB subunit were markedly reduced after K-80003 treatment. Also, K-80003 treatment inhibited 7-KC-induced p65 nuclear translocation, IκBα degradation, and transcription of NF-κB target genes. In addition, K-80003 inhibited NF-κB pathway mainly through the reduction of p62/sequestosome 1 (SQSTM1), probably due to promotion of autophagic flux by K-80003. Mechanistically, cytoplasmic localization of RXRα was associated with decreased autophagic flux. Increasing cytoplasmic RXRα expression by overexpression of RXRα/385 mutant decreased autophagic flux in RAW264.7 cells. Finally, K-80003 strongly inhibited 7-KC-induced RXRα cytoplasmic translocation.

CONCLUSIONS AND IMPLICATIONS

K-80003 suppressed atherosclerotic plaque progression and destabilization by promoting macrophage autophagic flux and consequently inhibited the p62/SQSTM1-mediated NF-κB proinflammatory pathway. Thus, targeting RXRα-mediated autophagy-inflammation axis by its noncanonical modulator may represent a promising strategy to treat atherosclerosis.

Allosteric small molecule modulators of nuclear receptors

Nuclear Receptors (NRs) are multi-domain proteins, whose natural regulation occurs via ligands for a classical, orthosteric, binding pocket and via intra- and inter-domain allosteric mechanisms. Allosteric modulation of NRs via synthetic small molecules has recently emerged as an interesting entry to address the need for small molecules targeting NRs in pathology, via novel modes of action and with beneficial profiles. In this review the general concept of allosteric modulation in drug discovery is first discussed, serving as a background and inspiration for NRs. Subsequently, the review focuses on examples of small molecules that allosterically modulate NRs, with a strong focus on structural information and the ligand binding domain. Recently discovered nanomolar potent allosteric site NR modulators are catapulting allosteric targeting of NRs to the center of attention. The obtained insights serve as a basis for recommendations for the next steps to take in allosteric small molecular targeting of NRs.

[Aryl-hydrocarbon receptor as a potential target for anticancer therapy]

Aryl-hydrocarbon receptor (Aryl Hydrocarbon Receptor, AHR) is a ligand-dependent transcription factor, whose functions are related to xenobiotic detoxification, response to inflammation, and maintenance of tissue homeostasis. Recent investigations suggest that AHR also plays an important role in the processes of carcinogenesis. Increased expression of AHR is observed in several types of tumors and tumor cell lines. In addition, it turned out that the composition of pharmaceutical drugs used in oncotherapy includes some ligands AHR. These facts allow us to consider an aryl-hydrocarbon receptor as a potential target for anticancer therapy, especially for the treatment of severe cancers whose treatment options are very limited or do not exist at all. In this review the examples of AHR ligands' effect on tumor cell cultures and on model mice lines with AHR-dependent response are discussed.

Ligand Dependent Switch from RXR Homo- to RXR-NURR1 Heterodimerization

Retinoid X receptors (RXRs) play key roles in many physiological processes in both the periphery and central nervous system. In addition, RXRs form heterodimers with other nuclear receptors to exert their physiological effects. The nuclear receptor related 1 protein (NURR1) is particularly interesting because of its role in promoting differentiation and survival of dopamine neurons. However, only a small number of RXR-heterodimer selective modulators are available, with limited chemical diversity. This work describes the synthesis, biochemical evaluation, and structural elucidation of a novel series of RXR ligands with strongly biased interactions with RXRα–NURR1 heterodimers. Targeted modifications to the small molecule biaryl scaffold caused local RXRα side-chain disturbances and displacement of secondary structural elements upon ligand binding. This resulted in the repositioning of protein helices in the heterodimer interface of RXRα, alterations in homo- versus heterodimer formation, and modulation of activation function 2 (AF2). The data provide a rationale for the design of RXR ligands consisting of a highly conserved hydrophilic region, strongly contributing to the ligand affinity, and a variable hydrophobic region, which efficiently probes the effects of structural changes at the level of the ligand on co-regulator recruitment or the RXRα–NURR1 dimerization interface.

Modulation of nongenomic activation of PI3K signalling by tetramerization of N-terminally-cleaved RXRα

Retinoid X receptor-alpha (RXRα) binds to DNA either as homodimers or heterodimers, but it also forms homotetramers whose function is poorly defined. We previously discovered that an N-terminally-cleaved form of RXRα (tRXRα), produced in tumour cells, activates phosphoinositide 3-kinase (PI3K) signalling by binding to the p85α subunit of PI3K and that K-80003, an anti-cancer agent, inhibits this process. Here, we report through crystallographic and biochemical studies that K-80003 binds to and stabilizes tRXRα tetramers via a ‘three-pronged’ combination of canonical and non-canonical mechanisms. K-80003 binding has no effect on tetramerization of RXRα, owing to the head–tail interaction that is absent in tRXRα. We also identify an LxxLL motif in p85α, which binds to the coactivator-binding groove on tRXRα and dissociates from tRXRα upon tRXRα tetramerization. These results identify conformational selection as the mechanism for inhibiting the nongenomic action of tRXRα and provide molecular insights into the development of RXRα cancer therapeutics.

The transcription factor retinoid X receptor-alpha (RXRα) can also form homotetramers. Here the authors show that the anti-cancer agent K-80003 selectively inhibits the nongenomic action of N-terminally-cleaved RXRα in tumour cells by stabilizing its tetramerization but not that of full-length RXRα.

Role of the aryl hydrocarbon receptor in carcinogenesis and potential as an anti-cancer drug target

The aryl hydrocarbon receptor (AhR) was initially identified as the receptor that binds and mediates the toxic effects induced by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and structurally related halogenated aromatics. Other toxic compounds including some polynuclear aromatic hydrocarbons act through the AhR; however, during the last 25 years, it has become apparent that the AhR plays an essential role in maintaining cellular homeostasis. Moreover, the scope of ligands that bind the AhR includes endogenous compounds such as multiple tryptophan metabolites, other endogenous biochemicals, pharmaceuticals and health-promoting phytochemicals including flavonoids, indole-3-carbinol and its metabolites. It has also been shown that like other receptors, the AhR is a drug target for multiple diseases including cancer, where both AhR agonists and antagonists effectively block many of the critical hallmarks of cancer in multiple tumor types. This review describes the anti-cancer activities of AhR ligands and demonstrates that it is time to separate the AhR from TCDD and exploit the potential of the AhR as a novel target for cancer chemotherapy.

Modification of the Orthosteric PPARγ Covalent Antagonist Scaffold Yields an Improved Dual-Site Allosteric Inhibitor

GW9662 and T0070907 are widely used commercially available irreversible antagonists of peroxisome proliferator-activated receptor gamma (PPARγ). These antagonists covalently modify Cys285 located in an orthosteric ligand-binding pocket embedded in the PPARγ ligand-binding domain and are used to block binding of other ligands. However, we recently identified an alternate/allosteric ligand-binding site in the PPARγ LBD to which ligand binding is not inhibited by these orthosteric covalent antagonists. Here, we developed a series of analogs based on the orthosteric covalent antagonist scaffold with the goal of inhibiting both orthosteric and allosteric cellular activation of PPARγ by MRL20, an orthosteric agonist that also binds to an allosteric site. Our efforts resulted in the identification of SR16832 (compound 22), which functions as a dual-site covalent inhibitor of PPARγ transcription by PPARγ-binding ligands. Molecular modeling, protein NMR spectroscopy structural analysis, and biochemical assays indicate the inhibition of allosteric activation occurs in part through expansion of the 2-chloro-5-nitrobenzamidyl orthosteric covalent antagonist toward the allosteric site, weakening of allosteric ligand binding affinity, and inducing conformational changes not competent for cellular PPARγ activation. Furthermore, SR16832 better inhibits binding of rosiglitazone, a thiazolidinedione (TZD) that weakly activates PPARγ when cotreated with orthosteric covalent antagonists, and may better inhibit binding of endogenous PPARγ ligands such as docosahexaenoic acid (DHA) compared to orthosteric covalent antagonists. Compounds such as SR16832 may be useful chemical tools to use as a dual-site bitopic orthosteric and allosteric covalent inhibitor of ligand binding to PPARγ.

Probing the Complex Binding Modes of the PPARγ Partial Agonist 2-Chloro-N-(3-chloro-4-((5-chlorobenzo[d]thiazol-2-yl)thio)phenyl)-4-(trifluoromethyl)benzenesulfonamide (T2384) to Orthosteric and Allosteric Sites with NMR Spectroscopy

In a previous study, a cocrystal structure of PPARγ bound to 2-chloro-N-(3-chloro-4-((5-chlorobenzo[d]thiazol-2-yl)thio)phenyl)-4-(trifluoromethyl)benzenesulfonamide (1, T2384) revealed two orthosteric pocket binding modes attributed to a concentration-dependent biochemical activity profile. However, 1 also bound an alternate/allosteric site that could alternatively account for the profile. Here, we show ligand aggregation afflicts the activity profile of 1 in biochemical assays. However, ligand-observed fluorine (¹⁹F) and protein-observed NMR confirms 1 binds PPARγ with two orthosteric binding modes and to an allosteric site.