(W1030-03-18) Exploring the Potential of Inhaled Clofazimine Liposomes for Mesothelioma Treatment

Purpose: Malignant Pleural Mesothelioma (MPM) is a rare type of cancer occurring in the pleural lining around the lungs, predominantly caused by exposure to asbestos. The prognosis of MPM is poor, with a meager patient survival rate ( < 10%) and an average life expectancy period of about a year. Current treatment options include chemotherapy (Cisplatin + Pemetrexed), surgical resection, radiation (as palliative care), or combinational therapy; recent addition includes Immunotherapy (Nivolumab + Ipilimumab). However, these therapies are not without limitations. Even after such extensive treatment, the chances of recurrences are high (75%). Moreover, these therapies provide systemic exposure to drugs, which further leads to off-target effects with limited efficacy at the target site. The overall survival increment was only ~13 months for these therapies. One reason behind the lack of effectiveness could be the failure to localize the treatment at the target site (lungs). However, the systemic adverse effects and limited efficacy further restrict its application. Recently, an inhaled formulation of CFZ suspension for the treatment of Nontuberculous mycobacterial (NTM) lung disease advanced Phase 2/3 studies to achieve the direct delivery of inhaled CFZ to the lungs (1). Our research group previously established the efficacy of the anti-tuberculosis drug clofazimine (CFZ), which has been shown to inhibit autophagy and induce apoptosis in MPM cells (2). In the present study, we aim to develop an inhaled CFZ-liposomal formulation that will enhance the therapeutic efficacy of CFZ by overcoming systemic toxicity and delivering the drug to the target site at a reduced dose with fewer side effects.

Methods: CFZ-loaded liposomes were prepared using the conventional thin-film hydration method using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and Cholesterol (molar ratio of 7: 3). Multiple formulations were formulated to develop a robust formulation by varying the CFZ amount (2 and 5 mg) and total lipid concentration (5 and 10 mM). The prepared formulations were tested for their physicochemical characterization, such as particle size (nm), zeta potential (mV), polydispersity index (PDI), and entrapment efficiency (%).

Results: As shown in Figure 1, Four different CFZ-loaded liposomes were formulated by the thin-film hydration method, which yielded a particle size range (188.6±12.9 nm to 401.1±0.02 nm), with all the formulations giving a PDI of ~ 0.4. A higher drug loading of 6.42±0.26% with a significant entrapment of 30.70±1.2 % was achieved for F4 with 10 mM total lipid content.

Conclusion: The present study aims to deliver CFZ via inhaled therapy as a novel therapy for MPM. To develop a robust liposomal-based formulation, we utilized a based strategy and varied the amount of CFZ and total lipid concentration. The present study is still under investigation, further focusing on evaluating the efficacy of optimized liposomal formulation in MPM-relevant cell lines using various in-vitro-based assays.  Furthermore, we will also evaluate the suitability of liposomes for inhalation-based therapy and in-vitro release to assess the release profile of CFZ under lung physiological conditions.

References: 1. Clofazimine Inhalation Suspension Demonstrates Promising Toxicokinetics in Canines for Treating Pulmonary Nontuberculous Mycobacteria Infection | Antimicrobial Agents and Chemotherapy [Internet]. [cited 2024 May 1]. Available from: https://journals.asm.org/doi/10.1128/aac.01144-22
2. Repurposing clofazimine for malignant pleural mesothelioma treatment — In-vitro assessment of efficacy and mechanism of action - ScienceDirect [Internet]. [cited 2024 May 1]. Available from: https://www.sciencedirect.com/science/article/abs/pii/S0024320522005434


Figure 1. Different CFZ-loaded formulations



Figure 2. Representative images of F4 (A) Particle size, (B) Zeta potential