NOS recoupling with L-citrulline, folate, and vericiguat in a NOX5-positive subgroup of HFpEF patients: A Phase IIa proof-of-concept trial

To test the hypothesis of a causal mechanism subtype in HFpEF related to uncoupled NO synthase and apo-sGC, a monocentric, prospective, randomized, standard treatment-controlled, open-label, phase IIa, proof-of-concept clinical trial (REPO-HFPEF IIa) was conducted. 21 HFpEF patients were randomized and exposed for 12 weeks in a 2:1 ratio to the standard of care (SOC) with or without a triple combination of vericiguat, L-citrulline, and folate. Patients were eligible if they were positive for the mechanism-based biomarker plasma NOX5 (≥ 105 ng/ml), apo-sGC-positive (apo-sGC/sGC ratio >1.05), or both. The total count of adverse events (AEs) between treatment groups was 22 in 14 patients in the REPO group and 6 in 7 in the SOC group. The median of peak VO2 at screening for the REPO and SOC groups was 13.1 ml/min/kg (9.4-14.1) and 10.6 ml/min/kg (7.9-12.3), respectively. In a linear mixed regression analysis, the least square mean difference for peak VO2 at visit 4 (end of treatment) was +0.27 (95% CI: -0.74 to 1.27) and -0.23 (95% CI: -1.13 to 0.68) for the REPO and SOC groups, respectively (between treatment p-value=0.340). The effect of treatment on KCCQ, peak VO2, and NT-pro-BNP did not significantly differ across NOX5 and sGC. However, we found a numerical trend towards improvement in KCCQ (+11.9 vs. -13.9, interaction p-value=0.116), peak VO2 (+1.54 vs. +0.45, interaction p-value=0.751), and NT-pro-BNP (-1135.9 pg/ml vs. +658.7 pg/ml, interaction p-value=0.166) in REPO-treated NOX5-positive patients. This differential effect was not found across apo-sGC-positive vs. negative patients: KCCQ (1.2 vs. 11.9, interaction p-value=0.410), peak VO2 (+0.41 vs. 1.91, interaction p-value=0.568), and NT-pro-BNP (-1288.5 pg/ml vs. 298.7 pg/ml, interaction p-value=0.288). Thus, network pharmacology with vericiguat, L-citrulline, and folate in a subgroup of NOX5-positive HFpEF patients is not associated with an increased overall risk of adverse events. There were some numerical signals toward improvement in HF-related quality of life, exercise capacity, and NT-pro-BNP reductions. Further studies with a larger sample size are necessary to validate these findings.