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Context Standard of care in PNH is based on complement C5 inhibition with anti-C5 monoclonal antibodies (MAbs), which are generally effective at treating intravascular hemolysis (IVH), but unmet needs remain. Hematological responses to anti-C5 antibody treatment can be heterogeneous, and a substantial number of patients experience residual anemia associated with breakthrough hemolysis (BTH). Iptacopan, a first-in-class, oral, small-molecule, selective, and reversible complement factor B inhibitor, inhibits both IVH and extravascular hemolysis. In an ongoing Ph2 study (NCT03439839), iptacopan has demonstrated improvements in hematological response and biomarkers of disease activity in PNH adult patients who had active hemolysis, despite eculizumab treatment. Objective APPOINT-PNH study (NCT04820530) will assess iptacopan efficacy and safety in PNH adult patients naive to complement inhibitors, including anti-C5 MAbs. Design The study comprises ≤8-wk screening; 24-wk, single-arm, open-label core treatment; and 24-wk, open-label treatment extension. On completion of week 24, patients who benefit from iptacopan treatment can enter extension. Eligible adult patients (N≈40) have confirmed PNH diagnosis (RBCs and WBCs [granulocyte/monocyte] clone size ≥10%); anemia (mean Hb 1.5× ULN). Key exclusion criteria: prior treatment with complement inhibitor; known or suspected hereditary complement deficiency; history of HSCT; laboratory evidence of bone marrow failure; active, systemic infection ≤14 days preceding study treatment; and history of recurrent, invasive infections caused by encapsulated microorganisms. Primary objective will assess hematologic response, defined as achieving sustained increase in Hb ≥2g/dL (in absence of RBC transfusions). Primary endpoint will evaluate proportion of patients achieving an increase from baseline in Hb ≥2g/dL between D126–D168 (in absence of RBC transfusions between D14–D168). Secondary endpoints include proportion of patients reaching Hb ≥12g/dL; absence of RBC transfusions; changes from baseline in Hb; changes in FACIT-Fatigue scores; changes from baseline in reticulocytes; % change from baseline in LDH; occurrence of BTH; and occurrence of major adverse vascular events (including thrombosis). Additional analyses include safety assessments; evolution of PNH clone size and C3d deposition on RBCs; and other PROs. Conclusions Ph3 studies to assess iptacopan efficacy in a wider population of PNH patients, including those naive to anti-C5 MAbs treatment, are needed. Study sponsored by Novartis Pharmaceuticals Corporation.

Telomerase reverse transcriptase (TERT) is the catalytic subunit of telomerase complex that regulates telomerase activity to maintain telomere length for all animals with linear chromosomes. As the Mus musculus (MM) laboratory mouse has very long telomeres compared to humans, a potential alternative animal model for telomere research is the Peromyscus leucopus (PL) mouse that has telomere lengths close to the human range and has the wild counterparts for comparison. We report the full TERT coding sequence (pTERT) from PL mice to use in the telomere research. Comparative analysis with eight other mammalian TERTs revealed a pTERT protein considerably homologous to other TERTs and preserved all TERT specific-sequence signatures, yet with some distinctive features. pTERT displayed the highest nucleotide and amino acid sequence homology with hamster TERT. Unlike human but similar to MM mice, pTERT expression was detected in various adult somatic tissues of PL mice, with the highest expression in testes. Four different captive stocks of PL mice and wild-captured PL mice each displayed group-specific average telomere lengths, with the longest and shortest telomeres in inbred and outbred stock mice, respectively. pTERT showed considerable numbers of synonymous and nonsynonymous mutations. A pTERT proximal promoter region cloned was homologous among PL and MM mice and rat, but with species-specific features. From PL mice, we further cloned and characterized ribosomal protein, large, P0 (pRPLP0) to use as an internal control for various assays. Peromyscus mice have been extensively used for various studies, including human diseases, for which pTERT and pRPLP0 would be useful tools.

A palmitate linked to the inositol in glycosylphosphatidylinositol (GPI) is removed in the endoplasmic reticulum immediately after the conjugation of GPI with proteins in most cells. Previously, we identified PGAP1 (post GPI attachment to proteins 1) as a GPI inositoldeacylase that removes the palmitate from inositol. A defect in PGAP1 caused a delay in the transport of GPI-anchored proteins (GPI-APs) from the endoplasmic reticulum to the cell surface in Chinese hamster ovary cells, although the cell-surface expression of GPI-APs in the steady state was normal. Nevertheless, in most cells, GPI-APs undergo deacylation. To elucidate the biological significance of PGAP1 in vivo, we established PGAP1 knock-out mice. Most PGAP1 knock-out mice showed otocephaly, a developmental defect, and died right after birth. However, some survived with growth retardation. Male knock-out mice showed severely reduced fertility despite the capability of ejaculation. Their spermatozoa were normal in number, motility, and ability to ascend the uterus, but were unable to go into the oviduct. In vitro, PGAP1-deficient spermatozoa showed weak attachment to the zona pellucida and a severely diminished rate of fertilization. Therefore, an extra acyl chain in GPI anchors caused severe deleterious effects to development and sperm function.