Real world tebentafusp-tebn experience at a tertiary care referral center.

e21526 Background: Tebentafusp-tebn is an FDA approved therapy specifically for patients with metastatic uveal melanoma (MUM). The major challenge of this treatment is the weekly infusion schedule and potentially significant toxicity during the dose escalation and induction phase (Cycle 1). To overcome this challenge, we developed a treatment model consisting of an induction phase at a tertiary center of MUM and subsequent treatments at a local cancer center. Methods: This retrospective cohort study included patients who received Cycle 1 at our institution since FDA approval. Patients who received initial induction doses at other health systems were excluded. Data was collected by chart review. Cytokine release syndrome (CRS) was graded by ASTCT consensus guidelines. Results: From 3/14/2022-11/7/23, 26 patients received at least one dose of tebentafusp-tebn at our institution. 14/26 were female and median age was 69 (range 51-80). 24/26 patients had metastatic disease to the liver, followed by bone (6/26), lung (3/26), and others (5/26). Patients underwent a median of 2 (range 0-5) lines of therapy prior to tebentafusp-tebn initiation. Major side effects during Cycle 1 included CRS (22/26), rash/itching (24/26), and nausea (3/26). One patient developed grade 4 liver enzyme elevations. Of the patients who developed CRS, 77.3% (17/22) were grade 1, 13.7% (3/22) were grade 2, and 9.1% (2/22) were grade 3. 5/26 (19.2%) patients required at least one dose of steroid for management of CRS. The median number of hospitalizations for Cycle 1 was 3 (range 3-6). After Cycle 1, 21/26 (80.8%) patients were successfully transitioned to local health systems to continue outpatient weekly tebentafusp-tebn infusions, including 2 patients who went were able to continue of therapy in their home countries. 1 patient is in the process of transferring, 1 patient discontinued after dose escalation due to disease progression, and 3 patients decided to continue treatment at our institution. 19 patients who were transitioned to their local cancer centers in the US traveled a median of 107 miles (range 30-298 miles) for Cycle 1 at our institution, and a median of 23 miles (range 4-58 miles) after transition to local health systems. The median number of days patients received therapy was 203 days (range 22-610 days). Median time to progression was 12.6 weeks (range 5.8-65.6). 6/26 (23.1%) patients have received additional therapy upon progression while continuing tebentafusp-tebn. 12/26 patients are currently receiving therapy and 2 patients were lost to follow up after transferring to a local site. At time of review 19/26 patients were alive. Conclusions: This hybrid model of treatment (Cycle 1 at a tertiary center followed by continuation at a local cancer center) made weekly tebentafusp-tebn treatment safe and feasible for patients with MUM. Our single center experience demonstrates side effects and outcomes similar to what has been reported in the clinical trial.