Cambridge, MA – [Insert Date of Publication] – SpliSense, a clinical-stage biopharmaceutical company, has announced the commencement of a crucial Phase IIb clinical trial for its novel inhaled antisense oligonucleotide therapy, SPL84. This investigational treatment is specifically designed for individuals suffering from cystic fibrosis (CF) who carry the 3849+10 kilobase (Kb) C-to-T mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. The initiation of this trial marks a significant step forward in the development of potentially life-changing therapies for a challenging subset of the CF patient population.
The Phase IIb study, an extension of the successful SPL84-002 trial, will rigorously evaluate SPL84 in combination with existing CFTR modulator treatments. This approach aims to build upon the encouraging results observed in the earlier Phase IIa segment, which indicated both a favorable safety profile and early signs of clinical activity for SPL84. The company anticipates reporting top-line results from this pivotal trial in the second half of 2027, offering a clear timeline for further advancements in the therapeutic pipeline.
Unveiling SPL84: A Targeted Approach for a Specific CF Mutation
Cystic fibrosis is a rare, inherited disorder that causes severe damage to the lungs, digestive system, and other organs. It is caused by mutations in the CFTR gene, which affects the way certain cells transport salt and water. While significant progress has been made in treating CF with the advent of CFTR modulators, a considerable number of patients still have unmet needs, particularly those with specific, less common mutations.
SPL84 is an antisense oligonucleotide (ASO) therapy designed to address the underlying cause of CF in patients with the 3849+10 Kb C-to-T mutation. This particular mutation is known to result in a partially functional CFTR protein, and SPL84 aims to correct the splicing defect caused by this mutation, thereby restoring the production of a functional CFTR protein. The inhaled delivery method is intended to directly target the lungs, where the majority of CF-related complications manifest.
The current Phase IIb trial is a meticulously designed, placebo-controlled, double-blind, and randomized study. It will enroll approximately 40 participants, all of whom have at least one copy of the 3849+10 Kb C-to-T mutation. A critical aspect of this trial is that participants will be individuals already receiving stable treatment with approved CFTR modulator therapies, such as Trikafta, Kaftrio, or Alyftrek. This inclusion criterion is crucial, as it allows researchers to assess the potential additive benefit of SPL84 when combined with existing standard-of-care treatments, thereby exploring a new frontier in personalized CF management.
A Closer Look at the Trial Design and Objectives
The randomization ratio for the Phase IIb trial is set at 4:1, meaning that for every one participant receiving a placebo, four will receive the investigational therapy, SPL84. Participants will receive either 50mg of SPL84 or a placebo administered via inhalation once a week for a duration of 12 weeks. This dosing regimen and duration are based on the promising outcomes of the Phase IIa study.
The primary objective of this Phase IIb trial is to comprehensively assess the safety and tolerability of SPL84 when administered in combination with existing CFTR modulator therapies. This is paramount, as patient safety is always the highest priority in drug development. By carefully monitoring for any adverse events, researchers will gain valuable insights into the overall profile of SPL84 in this patient population.
Beyond safety, the trial has several key secondary objectives aimed at evaluating the potential efficacy of SPL84. These include:
- Lung Function Assessment: This will be measured using established metrics such as percent predicted forced expiratory volume in one second (ppFEV1) and percent predicted forced expiratory flow between 25% and 75% of the vital capacity (ppFEF25-75). These parameters are vital indicators of how well the lungs are functioning and are standard measures in CF clinical trials.
- Respiratory Symptom Evaluation: The impact of SPL84 on respiratory symptoms will be assessed using the Cystic Fibrosis Questionnaire-Revised (CFQ-R) respiratory domain scores. The CFQ-R is a validated patient-reported outcome measure that captures the subjective experience of living with CF, including symptoms like cough, mucus production, and shortness of breath.
Furthermore, the study incorporates exploratory analyses to gain a deeper understanding of SPL84’s mechanism of action and its broader impact. These exploratory objectives include:
- Sputum Microbiology: Analyzing sputum samples will provide insights into the presence and types of bacteria and other microorganisms in the airways. Changes in sputum microbiology could indicate a reduction in airway inflammation or infection, which are significant challenges for individuals with CF.
- Lung Clearance Index (LCI): The LCI is a more sensitive measure of lung ventilation inhomogeneity, which can detect early signs of lung disease that may not be apparent with standard spirometry.
The commitment to rigorous scientific evaluation across primary, secondary, and exploratory objectives underscores SpliSense’s dedication to thoroughly characterizing the potential of SPL84.
A Glimpse into the Promising Phase IIa Results
The initiation of the Phase IIb trial is directly informed by the positive outcomes of the earlier Phase IIa segment of the SPL84-002 study. In this preceding phase, SPL84 demonstrated a favorable safety profile, meaning it was generally well-tolerated by participants. Crucially, the therapy also exhibited encouraging signs of clinical activity, suggesting it could be making a tangible difference in the lives of patients.
According to company reports, a significant proportion of participants who received SPL84 in the Phase IIa study experienced a notable improvement in their lung function. Specifically, up to 70% of these participants demonstrated at least a five-point improvement in lung function from their baseline measurements. This is a compelling statistic, as even small improvements in lung function can have a meaningful impact on the quality of life and long-term prognosis for individuals with CF.
The current Phase IIb trial is designed to further substantiate these findings. It will provide a more comprehensive characterization of both the safety and the treatment effect of SPL84, particularly in the context of patients who are already benefiting from existing modulator therapy. This dual focus on safety and efficacy in a more advanced clinical setting is essential for moving SPL84 closer to potential regulatory approval and wider patient access.
Official Responses and Strategic Vision
The commencement of this pivotal Phase IIb trial has been met with enthusiasm from the company’s leadership. Gili Hart, CEO of SpliSense, expressed her excitement about the progression of the SPL84 program.
"Following the favourable safety and efficacy profile demonstrated in the Phase IIa study, we are excited to initiate the Phase IIb study," stated Hart. "This trial is designed to determine whether once-weekly SPL84 can provide additional clinical benefit for people with the 3849+10kb C-to-T mutation who are already receiving standard-of-care CFTR modulator therapy."
Hart’s statement highlights the strategic importance of the Phase IIb trial. It is not just about proving SPL84 works in isolation, but about demonstrating its value as an add-on therapy for a specific patient group that may not achieve optimal outcomes with current treatments alone. This approach aligns with the evolving landscape of CF care, which increasingly emphasizes personalized medicine and the combination of therapies to address the multifaceted nature of the disease.
The promising profile of SPL84 has not gone unnoticed by regulatory bodies. The therapy has already received significant designations that could expedite its development and review process. In the United States, SPL84 has been granted Fast Track designation by the Food and Drug Administration (FDA). This designation is intended to facilitate the development and expedite the review of drugs that treat serious conditions and fill an unmet medical need. Additionally, SPL84 has received Orphan Drug Designation from the FDA, which provides incentives for the development of drugs for rare diseases.
On the European front, SPL84 has secured PRIME (PRIority MEdicines) designation from the European Medicines Agency (EMA). The PRIME scheme offers early and enhanced dialogue with regulators to support the development of medicines that address unmet medical needs. These designations collectively underscore the perceived potential of SPL84 and the regulatory support for its advancement.
Broader Implications for Cystic Fibrosis Treatment
The initiation of SpliSense’s Phase IIb trial for SPL84 carries significant implications for the broader landscape of cystic fibrosis treatment. For individuals with the 3849+10 Kb C-to-T mutation, this represents a beacon of hope. While current CFTR modulators have revolutionized care, they are not universally effective, and a subset of patients still experiences progressive lung damage and a reduced quality of life. SPL84, by targeting a specific splicing defect, offers a personalized therapeutic strategy that could address the unique needs of this patient group.
The success of SPL84 as an add-on therapy would also pave the way for future research into combination therapies for other rare CFTR mutations. The field is increasingly moving towards a more granular understanding of how different mutations impact CFTR function and how various therapeutic modalities can be combined to achieve optimal outcomes. SpliSense’s work with SPL84 could serve as a model for developing targeted therapies for other genetic subtypes of CF.
Furthermore, the successful development of an inhaled ASO therapy like SPL84 could have broader implications for the treatment of other respiratory diseases. ASOs have the potential to address a wide range of genetic disorders by modulating gene expression. If SPL84 proves safe and effective, it could open doors for the development of similar inhaled ASO therapies for other conditions affecting the lungs, potentially revolutionizing treatment paradigms beyond CF.
The investment in this advanced clinical trial, coupled with the regulatory support already garnered, positions SpliSense as a key player in the ongoing fight against cystic fibrosis. The company’s strategic focus on addressing unmet needs within the CF community, particularly for those with specific genetic mutations, demonstrates a commitment to innovation and patient-centric drug development. As the clinical trial progresses towards its anticipated top-line results in the latter half of 2027, the medical and patient communities will be keenly watching for further evidence of SPL84’s potential to significantly improve the lives of individuals living with cystic fibrosis.
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