(625) Manufacturing and Device Development for SPL84-23-1, an Inhaled Antisense Oligonucleotide, Supporting a First-in-Human Clinical Study in CF Patients Carrying the 3849+10kb C-to-T mutation
Background: Synthetic oligonucleotides are a novel class of compounds with the potential to treat a wide spectrum of indications, such as ophthalmic, cancer, and rare diseases like CF. SpliSense’s lead compound SPL84-23-1 is an antisense oligonucleotide (ASO), given by inhalation, developed for the unmet need of CF patients carrying the 3849+10kb C-to-T mutation. SpliSense demonstrated CFTR activity in SPL84-23-1-treated patient-derived cell, as well as proper lung distribution with cellular penetration and a promising safety profile in mice and monkeys. The aim of the SPL84-23-1 drug product development plan is to generate a stable and functional clinical stage product for inhalation which provides proper delivery and exposure to the lungs (target organ), with minimal systemic exposure.
Methods: SPL84-23-1 Drug Substance (DS) synthesis was performed using phosphorothioate solid-phase chemistry, followed by purification, concentration, and lyophilization steps, all which were developed to meet regulatory requirements. As SPL84-23-1 is intended for an infection sensitive population, it is essential to ensure the final product is free of any microorganism. Therefore, DS compounded with the excipients underwent sterile filtration followed by aseptic filling to create a sterile Drug Product (DP).
Results: Four SPL84-23-1 DS batches and one DP batch were synthesized so far and were successfully released according to pre-defined specifications. The process demonstrated satisfactory purity levels of >91%, with relatively low levels of PS-PO impurity, which is considered an ‘oxidation marker’. To further investigate the compound stability, both DP and DS were placed in a 12-month stability program and shown to be stable at the 6-month time point under accelerated conditions. The formulation for inhaled delivery (i.e DP) was chosen and optimized following a thorough screening process based on chemical, physical, and functional means. Formulation compatibility with the chosen delivery device (nebulizer) showed a Mass Median Diameter of 3-5µm and an acceptable delivered dose with mass balance close to 100%. DP integrity post nebulization was assessed for content assay, purity, Identity and functional activity. Results proved that DP integrity was maintained following nebulization.
Conclusions: Based on the data generated so far, we were able to demonstrate that the SPL84-23-1 DS and DP are stable and functional, as well as in aerosol form following nebulization, and therefore is suitable for use in clinical studies for CF patients carrying the 3849+10kb C-to-T mutation.
