Novel peptide therapeutics to treat cystic fibrosis-related diabetes

Cystic fibrosis-related diabetes (CFRD) affects ~45% of CF adults and is associated with diabetic complications, increased mortality and an accelerated decline in lung function. In CFRD, proinflammatory and profibrotic responses to mutations in the CFTR anion channel exacerbate insulin-secreting β-cell dysfunction, but the underlying molecular mechanisms are not well defined. Orai1 is a plasma membrane Ca2+ channel that is hyperactive in CF, even in people with CF (pwCF) taking ETI. Orai1 regulation is critical for pancreatic health, and Orai1 hyperactivity is causal for acute pancreatitis and fibrosis. Ca2+ influx through Orai1 can induce pro- inflammatory gene transcription. Moreover, Orai1 activation increases inflammation in myeloid cells and induces dedifferentiation of both pancreatic β-cells and pancreatic stellate cells (PSCs). Thus, Orai1 activation is generally considered to be a “bad actor” in the pancreas. Indeed, inhibition of Orai1 with a small molecule antagonist reduced symptoms in acute pancreatitis patients. CF ferrets homozygous for the CFTRG551D mutation have human-like CFRD. These CF ferrets can be reared on ivacaftor, then during adolescence, this compound is slowly withdrawn, and these ferrets develop pancreatic disease. It has been proposed by researchers at the University of Iowa that studying pancreatic disease in these ferrets is a good opportunity to model human CF pancreatic disease. We have developed ELD607, an antagonist that inhibits Orai1 in a CFTR mutation-agonistic fashion. Our preliminary data indicated that 14 days of daily intramuscular (IM) treatment with ELD607 significantly reduced fasting, non-fasting and peak glucose levels after a mixed meal tolerance test (MMTT) in the chronic CF ferret model. ELD607 also normalized peripheral blood neutrophil, monocyte and lymphocyte levels in CF ferrets, and reduced fibrosis. ELD607 delivery was well-tolerated and we saw no adverse effects in weight or blood chemistry. Based on these data, we posit that suppression of Orai1 may be a novel target for the treatment of CFRD. Based on our preliminary data, we hypothesize that inhibition of Orai1 will reverse both inflammation and fibrosis, and restore β-cell function/glucose homeostasis in the CF pancreas. We have teamed up with Dr J. McGuire, a co-designer of the GLP-1 agonist semaglutide. Using his approach, we have developed a 2nd generation ELD607 peptide (ELD2711) that shows increased affinity to albumin which is predicted to yield improved pharmacokinetics (PK) and once per week intramuscular (IM) dosing. Thus, we will determine the in vivo PK and in vitro efficacy of ELD607 vs ELD2711 to determine which peptide is superior. Next, we will expose CF ferrets to the best peptide for 2 weeks and will (i) measure glucose levels and (ii) perform histology to better understand the impact of Orai1 inhibition on the CF pancreas. Phase I Aim 1. Evaluate ELD607 vs second-generation peptides for IM delivery to treat CFRD. 1a. Evaluate stability of 2nd gen peptides vs ELD607 in human, rat and ferret plasma. 1b. Determine in vitro potency and safety of ELD607 vs 2nd generation peptides in β-cells and PSCs. Phase II Aim 2. Determine pharmacodynamics of ELD607 and 2nd generation peptide in rats. Aim 3. Produce GLP grade ELD607 to support downstream development activities. Aim 4. Perform dose range finding for the optimized peptide in a ferret CFRD model. Aim 5. Determine whether the lead IM peptide reverses pancreatic remodeling in the CF ferret.