Preclinical Development of a Novel eNAMPT-Neutralizing mAb for Pulmonary Hypertension

ABSTRACT Pulmonary arterial hypertension (PAH) is a fatal disease (without curative therapies) that is critically influenced by dysregulated inflammatory pathways. This A1 R42 Fast Track STTR application focuses on eNAMPT (extra- cellular nicotinamide phosphoribosyltransferase) as a novel, highly attractive PAH target. Aqualung Therapeutics has developed a humanized eNAMPT-neutralizing mAb, ALT-100, to address the unmet need for therapies that improve right ventricular (RV) dysfunction/failure and PAH survival. Circulating eNAMPT is a damage-associ- ated molecular pattern protein (DAMP) that robustly activates innate immunity-driven inflammatory pathways via ligation of the Toll-like receptor 4 (TLR4). Our published/unpublished data strongly support involvement of eNAMPT in the pathobiology of human PH. First, we have reported that NAMPT RNA and protein expression and secretion are significantly increased in PBMCs and in remodeled lung vessels from PAH patients with these processes highly upregulated by PAH-relevant stimuli, including growth factors and hypoxia via HIF-2α signaling. Second, plasma eNAMPT levels are elevated and correlate with RV dysfunction in PAH subjects. Thirdly, NAMPT polymorphisms (SNPs), previously linked to inflammatory severity including ARDS mortality, are asso- ciated with PAH severity, including cardiac catherization indices of RV dysfunction in a large PAH GWAS. Lastly, we have compellingly demonstrated that eNAMPT is a highly druggable target, with the eNAMPT-neutralizing mAb, ALT-100, profoundly attenuating and reversing preclinical PAH vascular remodeling and indices of RV heart failure. Supporting the feasibility of ALT-100 as a PAH therapy, we have completed non-IND-enabling pharmacokinetic (PK) studies demonstrating that IV-delivered ALT-100 mAb exhibits a T1/2 half-life of 12-14 days and 28-day toxicity studies in rats demonstrated that up to 50 mg/kg of ALT-100 is without discernable toxicity. We have completed stable cell line development, generated both Research and Master Cell Banks, and have completed a 200L GMP Bioreactor run (expression 6 gms/L); a titer assuring very low Cost of Goods and market entry at a low price point. ALT-100’s acute IND-enabling studies for the indication of ARDS will to be completed by November 2021, again facilitating a successful FDA IND application for PAH. STTR PHASE I is designed to optimize route of delivery (SubQ vs IM) and dosing of ALT-100 mAb and further validate ALT-100 as an effective strategy in two preclinical PAH rat models (monocrotaline, hypoxia/Sugen) (SA #1). We will provide proof-of- concept genomic data validating ALT-100 targeting of the eNAMPT/TLR4 pathway in rat lung tissues and PBMCs as the mechanism by which ALT-100 significantly halts PAH progression and potentially reverses the severity of PAH (SA #2). PHASE II studies conducted in rats and minipigs will characterize the PK and pharmacodynamic (PD) characteristics of the ALT-100 mAb (SA #3) and ALT-100 toxicokinetic properties (SA #4). Successful completion of these PHASE I/ II STTR studies will enable submission of an FDA IND application whose approval will allow rapid movement to conducting PAH clinical trials that address the significant unmet need in PAH.PUBLIC HEALTH RELEVANCE - NARRATIVE Pulmonary Arterial Hypertension is a debilitating often fatal disease without a cure, a serious unmet need. The inflammatory protein, eNAMPT (extracellular nicotinamide phosphoribosyltransferase), is a key driver of unchecked inflammation and a highly novel therapeutic target and candidate gene in PAH. Our Phase I/II goals are to validate and optimize the eNAMPT- neutralizing humanized mAb, ALT-100, as a therapeutic strategy for PAH, and to complete IND-enabling studies that will facilitate ALT-100 development in human PAH trials.