Article Figures & Data
Figures
- Fig. 1.
PCFT, RFC, and FRα-mediated endocytosis in folate absorption, distribution, and renal tubular reabsorption (Kim et al., 2004; Solanky et al., 2010; Zhao et al., 2011). CSF, cerebrospinal fluid; GFR, glomerular filtration rate; PT, renal proximal tubule.
- Fig. 2.
Diagram of experimental setup for (A) PCFT transport, (B) RFC transport, and (C) FRα-mediated endocytosis studies. LDH, lactate dehydrogenase; TA, test article drug.
- Fig. 3.
PCFT transport of 10 nM [3H]-folic acid in the presence of (A) assay positive control inhibitor, bromosulfophthalein (nominal concentrations and IC50); (B) clinical positive control, methotrexate; (C) clinical negative control, valproic acid; (D) dolutegravir; (E) cabotegravir; (F) bictegravir; (G) elvitegravir; and (H) raltegravir. Black symbols represent PCFT [3H]-folic acid uptake activity at various test article concentrations, solid black line is IC50 curve fit with IC50 estimate shown wherever >50% inhibition was observed, red square symbols (B–H) denote PCFT activity in the presence of assay positive control (bromosulfophthalein at 300 μM nominal concentration), dashed blue line (B–H) represents 100% PCFT activity (i.e., no inhibition). All test article concentrations were determined experimentally at the end of the experiment, except bromosulfophthalein concentrations are nominal. Mean ± S.D., n = 4.
- Fig. 4.
RFC transport of 0.5 μM [3H]-methotrexate in the presence of (A) assay positive control inhibitor, pemetrexed (nominal concentrations and IC50); (B) clinical positive control, methotrexate; (C) clinical negative control, valproic acid; (D) dolutegravir; (E) cabotegravir; (F) bictegravir; (G) elvitegravir; and (H) raltegravir. Black symbols represent RFC [3H]-methotrexate uptake activity at various test article concentrations, solid black line is IC50 curve fit with IC50 estimate shown wherever >50% inhibition was observed, red square symbols (B–H) denote RFC activity in the presence of assay positive control (pemetrexed at 1 mM nominal concentration), dashed blue line (B–H) represents 100% RFC activity (i.e., no inhibition). All test article concentrations were determined experimentally at the end of the experiment, except pemetrexed concentrations are nominal. Mean ± S.D., n = 4.
- Fig. 5.
FRα-mediated endocytosis of 50 nM [3H]-folic acid in the presence of (A) assay positive control inhibitor, pemetrexed (nominal concentrations and IC50); (B) clinical positive control, methotrexate; (C) clinical negative control, valproic acid; (D) dolutegravir; (E) cabotegravir; (F) bictegravir; (G) elvitegravir; and (H) raltegravir. Black symbols represent FRα-mediated [3H]-folic acid uptake activity at various test article concentrations, solid black line is IC50 curve fit with IC50 estimate shown wherever >50% inhibition was observed, red square symbols (B–H) denote FRα activity in the presence of assay positive control (pemetrexed at 300 μM nominal concentration), and dashed blue line (B–H) represents 100% FRα activity (i.e., no inhibition). All test article concentrations were determined experimentally at the end of the experiment, except pemetrexed concentrations are nominal. Although elvitegravir elicited an apparent 14%–38% decrease in FRα-mediated folic acid cellular accumulation at the top two concentrations tested, this decrease was comparable in magnitude to 14%–27% cytotoxicity observed at these elvitegravir concentrations in this assay (Supplemental Table 3); therefore, no apparent inhibition of FRα by elvitegravir was concluded. Mean ± S.D., n = 4.
- Fig. 6.
Clinical extrapolation summary for PCFT, RFC, and FRα inhibition in folate absorption, distribution, and renal sparing.
Tables
- TABLE 1
Drug parameters relevant for clinical extrapolation of in vitro transport inhibition
Drug Mol. Wt. Dose Cmax fu Cmax,u Igut Reference g/mol mg µM µM µM Dolutegravir 441.36 50 8.32a 0.01 0.08a 453.14 Tivicay, Prescribing Information, 2018 Cabotegravir 427.33 30 14.88 0.01 0.15 280.81 Ford et al., 2019 Bictegravir 449.38 50 13.69 0.01 0.14 445.06 Biktarvy, Prescribing Information, 2018 Raltegravir 482.51 400 4.50 0.17 0.76 3315.99 Isentress (raltegravir) Prescribing Information, 2019 Raltegravir 482.51 1200 22.56 0.17 3.84 9947.98 http://wwwcroiconferenceorg/sessions/multiple-dose-study-raltegravir-ral-formulations Elvitegravir 447.88 85 2.68b 0.02 0.05b 759.13 Viteka Prescribing Information, 2015 Elvitegravir 447.88 150 3.35b 0.02 0.07b 1339.64 Viteka Prescribing Information, 2015 Methotrexate 454.44 10 0.57 0.5 0.28 88.02 Jylamvo (methotrexate) Prescribing Information, 2017 Methotrexate (i.v.) 454.44 15 3.80 0.5 1.90 N/A Seideman et al., 1993 Pemetrexed (i.v.) 597.49 500 mg/m2 189.12 0.19 35.93 N/A Kavathiya et al., 2017 Cmax,u, unbound Cmax (i.e., Cmax * fu); fu, plasma fraction unbound; Igut, theoretical gut concentration (oral dose/250 ml) or highest soluble aqueous concentration; oral administration in all cases, unless noted); N/A, not applicable (i.v. administration).
↵a Most commonly used 50-mg daily regimen; 50 mg twice daily; Cmax = 9.4 μM and Cmax,u = 0.09 μM (ViiV Healthcare, 2018), twice-daily dosing does not impact extrapolation values or results in Fig. 6.
↵b Not cobicistat boosted, 150-mg dose cobicistat-boosted Cmax = 3.8 μM and Cmax,u = 0.08 μM (2019); cobicistat boosting does not impact extrapolation values or results in Fig. 6.
Data Supplement
- Supplemental Data -
Supplemental methods, 1 figure, 2 tables.
- Supplemental Data -
