The hypoxia-inducible factor 2α (HIF-2α) is a key oncogenic driver in clear cell renal cell carcinoma (ccRCC). Our first HIF-2α inhibitor PT2385 demonstrated promising proof of concept clinical ...activity in heavily pretreated advanced ccRCC patients. However, PT2385 was restricted by variable and dose-limited pharmacokinetics resulting from extensive metabolism of PT2385 to its glucuronide metabolite. Herein we describe the discovery of second-generation HIF-2α inhibitor PT2977 with increased potency and improved pharmacokinetic profile achieved by reduction of phase 2 metabolism. Structural modification by changing the geminal difluoro group in PT2385 to a vicinal difluoro group resulted in enhanced potency, decreased lipophilicity, and significantly improved pharmacokinetic properties. In a phase 1 dose-escalation study, the clinical pharmacokinetics for PT2977 supports the hypothesis that attenuating the rate of glucuronidation would improve exposure and reduce variability in patients. Early evidence of clinical activity shows promise for PT2977 in the treatment of ccRCC.
HIF-2α, a member of the HIF family of transcription factors, is a key oncogenic driver in cancers such as clear cell renal cell carcinoma (ccRCC). A signature feature of these cancers is the ...overaccumulation of HIF-2α protein, often by inactivation of the E3 ligase VHL (von Hippel-Lindau). Herein we disclose our structure based drug design (SBDD) approach that culminated in the identification of PT2385, the first HIF-2α antagonist to enter clinical trials. Highlights include the use of a putative n → π*
interaction to guide early analog design, the conformational restriction of an essential hydroxyl moiety, and the remarkable impact of fluorination near the hydroxyl group. Evaluation of select compounds from two structural classes in a sequence of PK/PD, efficacy, PK, and metabolite profiling identified 10i (PT2385, luciferase EC
= 27 nM) as the clinical candidate. Finally, a retrospective crystallographic analysis describes the structural perturbations necessary for efficient antagonism.
HIF-2α, a member of the HIF family of transcription factors, is a key oncogenic driver in cancers such as clear cell renal cell carcinoma (ccRCC). A signature feature of these cancers is the ...overaccumulation of HIF-2α protein, often by inactivation of the E3 ligase VHL (von Hippel–Lindau). Herein we disclose our structure based drug design (SBDD) approach that culminated in the identification of PT2385, the first HIF-2α antagonist to enter clinical trials. Highlights include the use of a putative n → π*Ar interaction to guide early analog design, the conformational restriction of an essential hydroxyl moiety, and the remarkable impact of fluorination near the hydroxyl group. Evaluation of select compounds from two structural classes in a sequence of PK/PD, efficacy, PK, and metabolite profiling identified 10i (PT2385, luciferase EC50 = 27 nM) as the clinical candidate. Finally, a retrospective crystallographic analysis describes the structural perturbations necessary for efficient antagonism.
Monophosphate prodrug analogs of 2'-deoxy-2'-fluoro-2'-
-methylguanosine have been reported as potent inhibitors of hepatitis C virus (HCV) RNA-dependent RNA polymerase. These prodrugs also display ...potent anti-dengue virus activities in cellular assays although their prodrug moieties were designed to produce high levels of triphosphate in the liver. Since peripheral blood mononuclear cells (PBMCs) are among the major targets of dengue virus, different prodrug moieties were designed to effectively deliver 2'-deoxy-2'-fluoro-2'-
-methylguanosine monophosphate prodrugs and their corresponding triphosphates into PBMCs after oral administration. We identified a cyclic phosphoramidate, prodrug 17, demonstrating well-balanced anti-dengue virus cellular activity and
stability profiles. We further determined the PBMC concentration of active triphosphate needed to inhibit virus replication by 50% (TP
). Compound 17 was assessed in an AG129 mouse model and demonstrated 1.6- and 2.2-log viremia reductions at 100 and 300 mg/kg twice a day (BID), respectively. At 100 mg/kg BID, the terminal triphosphate concentration in PBMCs exceeded the TP
value, demonstrating TP
as the target exposure for efficacy. In dogs, oral administration of compound 17 resulted in high PBMC triphosphate levels, exceeding the TP
at 10 mg/kg. Unfortunately, 2-week dog toxicity studies at 30, 100, and 300 mg/kg/day showed that "no observed adverse effect level" (NOAEL) could not be achieved due to pulmonary inflammation and hemorrhage. The preclinical safety results suspended further development of compound 17. Nevertheless, present work has proven the concept that an efficacious monophosphate nucleoside prodrug could be developed for the potential treatment of dengue virus infection.
Electrospray ionization mass spectrometry (ESI-MS) was used to probe multiple cation complexation by C12H25〈N18N〉(CH2)12〈N18N〉(CH2)12〈N18N〉C12H25, 2, and 〈18N〉CH2C6H4CH2〈N18〉, 3. Complexation of two ...cations (2Na+, 2 K+, or Na+ and K+) by 3 and three cations by 2 (3 Na+, 3 K+, and mixtures) as well as mixed proton−metallic cation complexes of both were observed. The K+/Na+ cation-binding selectivity of 18-crown-6 was studied by ESI-MS of a methanol solution, and the selectivity profile was favorably compared with data obtained previously by ion-selective electrode techniques in the same solvent.
Currently, there are no well-defined markers for distinguishing ischaemia from reperfusion injury. In this study, the practicality of a diagnostic health sensor was examined via the investigation of ...voltammetric alkaline phosphatase (ALP) detection. An indium tin oxide (ITO) film on glass was employed in the fabrication of an electrochemical sensor via facile photolithography using a transparent film and an office printer. The enzymatic hydrolysis of the substrate p-nitrophenyl phosphate (PNPP) by ALP produces p-nitrophenol, which was quantified by square wave voltammetry (SWV) and cyclic voltammetry (CV). Untreated human blood (UHB), human serum (HS), foetal bovine serum (FBS), and many other media provide a platform for ALP detection via this technique, which has a linear range of 5–250 U/L. The standard colorimetric analysis method was performed to further confirm the results.
Pharmacokinetic properties of our first-generation HIF-2α antagonist PT2385, including modest solubility, resulted in a high recommended phase 2 dose (RP2D) of 800 mg BID and motivated the pursuit of ...novel scaffolds which could improve solubility and formulation parameters with the goal of improved pharmacokinetics. Herein we disclose our successful efforts to identify such HIF-2α antagonists through an optimization strategy characterized by: (1) increasing the fraction of sp
3
hybridized carbons (Fsp
3
), (2) replacing the aromatic portion of the indane core with pyridine heterocycles, and (3) improving a putative O
lp
→π*
Ar
interaction, an underutilized electrostatic contact in medicinal chemistry. These efforts emphasize the importance of employing multiple strategies in parameter optimization. In isolation, modifications to areas (1) and (2) improved solubility, but with the compromise of reduced potency. In area (3), understanding the importance of an O
lp
→π*
Ar
interaction, as documented through a wealth of crystal structures and retrospective calculations, proved essential in guiding SAR and identifying the trifluoromethyl group as a suitable replacement of the sulfone. Only by combining these three strategies could inhibitors with substantially improved solubility and comparable potency be discovered. Finally, the overall improvement in pharmacokinetic properties of the newly identified inhibitors is highlighted through a battery of ADME and in vivo data, including use of pharmacodynamic biomarkers indicative of HIF-2α antagonism.
A family of 15 ferrocene derivatives has been prepared, most of which are reported for the first time. This includes FcCH2O-3-cholestanyl, 1; FcCH2O(CH2)13CH3, 2; FcCH2O(CH2)15CH3, 3; ...FcCH2O(CH2)17CH3, 4; FcCH2N(CH2)17CH32, 5; FcCH2O(CH2)8OCH2Fc, 6; FcCH2O(CH2)12OCH2Fc, 7; FcCH2O(CH2)16OCH2Fc, 8; Fc(CH2)22Fc, 9; FcCH2-3,17-β-estradioxy-CH2Fc, 10; Fc-1,1‘-COO(CH2)16CH3, 11; FcCONH(CH2)17CH3, 12; Fc-1,1‘-{CON(CH2)17CH32}2, 13; Fc-1,1‘-(COO-3-dihydrocholesteryl), 14; and Fc-1,1‘-(COO-3-cholesteryl), 15. Redox potentials for 1−15 have been determined and are in the range 400−450 mV for 2−6 (vs SSCE) and 509 mV for 1, 972 mV for 7, 806 mV for 8, 711 mV for 9, 941 mV for 10, and 945 mV for 11 (vs Ag/AgCl). Upon oxidation with Ce(IV), aqueous suspensions of compounds 1−5 and 7−10 formed stable vesicles after sonication. The charged monomers that formed vesicles afforded aggregates in the 2000−3000 Å range that were characterized by laser light scattering and negative stain electron microscopy. In the absence of an oxidizing agent, vesicles failed to form from any of the 15 monomers even after prolonged sonication. Addition of 500 μM aqueous Na2S2O4 solution collapsed the vesicles formed from 1−5 and 7−10, and the original amphiphile monomers were detected afterward by thin layer chromatography. It was concluded from cyclic voltammetry that both ferrocene residues in 8 were oxidized. Vesicles formed from 7−10 represent the first examples of a redox-switched bolaamphiphile.
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