Abstract 98P
Background
Osteosarcoma is the most common primary malignant bone tumor in pediatric and adolescent populations. Standard treatment consists of neo adjuvant chemotherapy, complete surgical resection and adjuvant chemotherapy, with 5-year EFS of 60-70% in patients with non-metastatic OS. Mifamurtide (Mepact), is synthetic lipophilic analogue of muramyl dipeptide, peptidoglycan contained in the bacterial wall, activating the innate immune system, and act as a nonspecific immunomodulatory agent. Its benefit in addition to chemotherapy was demonstrated in patients with local complete resected OS after surgery, with significantly improved 6-year overall survival from 70% to 78%. Herein we present our experience with Mifamurtide treatment, its safety, toxicity management and feasibility.
Methods
This is a retrospective study done between the years 2012 and 2022. Included are 37 patients receiving 1680 doses of Mifamurtide. There were 18 males and 19 females, median age of 16 (range 5-22 years). Patients' data was collected from electronic files. Each patient was planned to receive 48 doses of Mifamurtide 2mg/m2, twice a week for 12 weeks and then once a week for 24weeks. All patients received premedication using antipyretics, antihistamine and pethidine.
Results
There were 120 toxicity events out of 1680 doses of Mifamurtide. Thirty out of thirty-seven (81%) patients experienced toxicity including fever Grade 1-2 in 4 patients (13%), headache grade 1-2 in 2 patients (5%), chills grade 1-2 in 24 patients (80%), and hospitalization due to fever for antibiotic treatment in 4 patients (11%). No grade 3-4 toxicity was demonstrated. Sixty-seven percent of grade 1-2 toxicity occurred in the setting of twice a week administration. In patients who experienced chills, post medication with pethidine and antihistamine was added, and for than on, no patient was hospitalized due to side effects. Apart from four patients with progressive disease, all others completed 48 doses of Mifamurtide.
Conclusions
No incidence of grade 3-4 toxicity was documented. Using pre and post medication, administration of Mifamurtide was feasible and safe. Toxicity was more common in twice-weekly schedule, and apart from 4 patients with tumor progression, all others completed treatment.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.