Background and Importance Chronic graft versus host disease (cGVHD) associated oral mucositis is a complication after stem-cell transplantation. Corticosteroids are the standard treatment, but there is no consensus in case of refractory lesions. Platelet concentrates may be a safe treatment option.

Aim and Objectives Design a sterile oral formulation able to release platelet lysate (PL) on oral cavity, and evaluate its effectiveness in a series of cases.

Material and Methods PL gel 25% was compounded by mixing in aseptic conditions 1:1 carboxymethyl cellulose sodium base 5% previously autoclaved with PL also diluted 1:1 with sodium chloride 0.9%. PL gel was packaged in 3mL aliquots using oral syringes, which were stored in the freezer until their use. Galenic validation was performed.

Patients with cGVHD associated oral mucositis from November 2021 to August 2022 who accepted to initiate oral PL gel were monitored. Effectiveness was evaluated based on severity of the oral mucositis (NCI-CTCAE Grade 1-4). Patient satisfaction was self-assessed in a visual scale 0-10 according to the degree of pain/discomfort. Adherence was assumed based on the number of syringes dispensed.

Results PL gel obtained was slightly yellow, translucent, pH=6, with medium consistency that leads adequate bioadhesive characteristics. No changes of pH, colour, weight, or microbial growth were observed during galenic validations. A beyond-use date of 45 days at -20°C was given.

Six patients with moderate oral mucositis (grade 3) who failed to first-line topical steroids therapy started PL gel. Two of six discontinued after one month because their lifestyle prevented them from preserving the gel properly. Four patients (three men, one woman) went on with the gel for an average of 5 months (range 3-9). Clinical evaluation showed an improvement of 1 degree in oral mucositis in three patients and 2 degrees in the patient with the longest treatment (9 months). The self-assessment scale showed an average decrease of pain/discomfort of 2 points. Estimated adherence in patients who received the treatment for more than one month was 80.8% (95% CI: 56.8-104.9).

Conclusion and Relevance The formulation of a gel based on sodium carboxymethyl cellulose was adequate to administer PL on the oral cavity. Four patients with cGVHD associated oral mucositis refractory to standard treatment were successfully treated.

Conflict of Interest No conflict of interest