Metformin Repurposing in Oral Submucous Fibrosis: Unveiling In Vitro Signaling Pathways, Progressing to Clinical Trial

OSF stands as a persistent inflammatory and potentially malignant condition affecting the oral cavity, marked by progressive fibrosis of the oral mucosa. The spectrum of its manifestations spans from initial inflammation to the gradual emergence of fibrous bands, leading to restricted mouth opening and mucosal rigidity. Common symptoms encompass burning sensations, difficulty in swallowing, and alterations in taste perception. This health concern has gained prominence in Pakistan, experiencing a worrisome surge in prevalence from 8.3/105 to 16.2/105 in recent years. Formerly confined to Southeast Asia, OSF has now transcended borders, manifesting in Asian immigrant communities in Britain and America, evolving into a global oral potential malignant disorder (OPMD) with a malignant rate of 9.13% .

Presently, the corticosteroid-based approach effectively reduces inflammation in OSF but falls short in addressing the underlying molecular mechanisms contributing to fibrosis. Furthermore, the prolonged use of corticosteroids raises concerns about adverse effects, including mucosal atrophy and compromised tissue integrity. This study aims to investigate the potential of metformin, a recognized emerging drug for treating fibrosis, and its anti-fibrotic properties in various organs. The established safety profile of metformin adds an advantageous aspect to its potential applications.

Numerous studies indicate that metformin exhibits anti-fibrotic effects by inhibiting TGF-β1 production, reducing phosphorylation and nuclear translocation of Smad2/3. Additionally, metformin inhibits Smad2/3 phosphorylation independently and activates AMPK, hindering Smad3 phosphorylation. The impact on reactive oxygen species (ROS) generation moderates TGF-β1-induced Smad2/3 phosphorylation and myofibroblast differentiation.Metformin has shown promise in hindering collagen production and promoting trans differentiation in various organ, including the lung, kidney, heart and adipose tissue. A clinical trial reported metformin therapy's impact on postmenopausal ovaries, patients with type 2 diabetes mellitus (T2DM) exhibited isotropic collagen organization and reduced fibrosis during oophorectomy.The observed risk reduction for ovarian cancer in T2DM women using metformin suggests its potential as an ovarian cancer prophylaxis. Despite conflicting clinical trial results in liver fibrosis, metformin consistently improves hepatocyte damage and inflammation. Clinical trials have explored the role of metformin antitumor activity when combined with conventional chemotherapeutic drugs and in idiopathic pulmonary fibrosis it inhibits TGFβ1, suppressing collagen formation, activating PPARγ signaling and inducing lipogenic differentiation.

Inclusion criteria

• Patients with OSF- palpable bands on oral examination
• Patients with limited mouth opening due to OSF
• Patients who have not received any treatment for OSF in the previous three months
• Patients with habits of pan, Chalia, Ghutka
• Age group between 18 and 45 years

Exclusion criteria

• Patients presenting with both OSCC and OSF
• Patients with limited mouth opening due to impaction of the third molar (impaction of third molar results in limited mouth opening hence such patients are excluded since limited mouth opening due to third molar impaction can be mistaken for OSF).
• Patients with limited mouth opening due to temporomandibular joint disorder (temporomandibular joint disorders can limit the ability of patient to open their mouth and hence can be mistaken for OSF)
• Any history of Metformin intolerance or contraindications.
• Presence of other severe medical conditions along with drug therapy.
• Pregnancy or lactation.
• Participation in other clinical trials concurrently.
• Inability to provide informed consent.