029: In Vitro & In Vivo Assessment on Endogenous Biomarkers for Studying Renal Transporter (OCT2, MATE1/2-K) Mediated Drug Interaction & Disease Impact Consideration in Novel Endogenous Biomarker, N1-Methyladenosine: A Systematic Review

Statement of Purpose: Regulatory agencies provide guidance on in vitro and clinical drug interaction (DDI) studies for drug development. However, conservative IC₅₀/C_max cut-off values may necessitate a larger number of clinical DDI studies, leading to restrictions in co-medication or patient recruitment for Phase II/III studies and impacting drug labeling. To enhance efficiency in drug development, the use of endogenous biomarkers in transporter-mediated drug interaction has been explored. This systematic literature review aimed to investigate potential endogenous biomarkers for renal transporter-mediated drug interaction, specifically OCT2, MATE1/2-K, by reviewing in vitro and in vivo literature from external and Boehringer Ingelheim (BI) internal database.

Description of Methods & Materials: External literature was collected from PubMed, Ovid, and the Univ of Washington DDI Database, using search and operational terms: “endogenous biomarker,” “renal transporter,” “drug interaction,” “OCT,” “MATE,” “AND” and “OR”. BI internal literature was gathered based on endogenous biomarker use in clinical DDI studies. A title review was then conducted, followed by categorization of information into pharmacokinetics, the impact of disease on endogenous biomarker level in humans, and the use of endogenous biomarkers in cancer diagnosis.

Data & Results: Based on available literature, three endogenous biomarkers, N1-methyladenosine (m¹A, N=58), N1-methylnicotinamide (NMN, N=56), and creatinine (N=4200), have been more extensively studied than other biomarkers—glycochenodeoxycholic acid-sulfate (N=9), homovanillic acid (N=238), Isobutyryl-L-carnitine (N=2), pyridoxic acid (N=13), and taurine (N=257)—in the context of renal transporter-mediated drug interaction. Based on in vitro uptake ratios (UR), NMN and creatinine were identified as substrates of renal transporters OCT2, MATE1/2-K, while m¹A was a substrate of only OCT2 and MATE2-K (UR >2-fold). The three biomarkers, m¹A , NMN, and creatinine, were fully inhibited by pyrimethamine. Renal clearance of these biomarkers was calculated using kinetic data from their K_m and V_max values (Table 1). To summarize in vivo endogenous biomarker data on renal transporter-mediated drug interactions, correlation coefficients (R²) of m¹A, NMN, and creatinine against metformin (10 mg or 500 mg) renal clearance (CL_r,0-12h for NMN, creatinine, and metformin; CL_r,0-24h for m¹A, creatinine, and metformin) adjusted geometric mean ratios (Test/Reference) were determined with or without administration of known inhibitors (single doses of pyrimethamine 10/25/75 mg or multiple doses of cimetidine 400 mg) or a potential inhibitor (multiple doses of BI 730357 300 mg). Compared to metformin 500 mg, the calculated R² rank order was m¹A (0.65) > NMN (0.53) > creatinine (0.11). A separate clinical study also exhibited a similar decreasing R² trend (NMN: 0.87; creatinine: 0.71) (Table 1 & Figure 1). The impact of disease on m¹A levels was also observed: elevated m¹A levels in colon (serum and urine), ovarian (urine), and cervix (urine) cancer patients; significant inter- and intra- variations in breast, lung, and gastric cancer patients; a more prevalent 24-hour rhythmic pattern in metastatic colorectal cancer patients; and a high false-positive rate in renal dysfunction.

Interpretation, Conclusion or Significance: Overall, m¹A, NMN, and creatinine are recognized as endogenous substrates of OCT2 and MATEs. m¹A displayed the strongest correlation with metformin in assessing renal transporter-mediated drug interaction in clinical settings. Additionally, NMN consistently performed as an endogenous biomarker under both inhibiting and non-inhibiting conditions of renal transporters.

Disclosures: All authors are employees of Boehringer Ingelheim GmbH.