P193 | BEYOND PAIN MANAGEMENT: EXPLORING THE ROLE OF RADIOTHERAPY FOR PATIENTS WITH RELAPSED-REFRACTORY MULTIPLE MYELOMA

Osteolytic lesions are a clinically significant feature of multiple myeloma, frequently posing a challenge for pain management. Radiotherapy is a well-established intervention for pain relief and stabilization of these lesions; however, its impact on patient’s outcome remains ambiguous. This retrospective study aimed to examine disease characteristics and survival outcomes in patients with relapsed/refractory multiple myeloma treated at our institution between 2019 and 2024 who received sequential local radiotherapy and systemic therapy. The analysis included 14 RRMM patients (7 male, 7 female) with a median age of 73 years at the time of relapse. Patients had received a median of one prior line of therapy. The best response to the most recent prior line of therapy was VGPR in 57% of patients (n = 8), PR in 21% of patients (n = 3), and CR in 22% of patients (n = 3). At the time of relapse, 8 patients presented with bone involvement only (1 also with lung involvement), 4 had anemia, 1 had anemia and renal impairment, and 1 exhibited all CRAB criteria. All patients were candidates for systemic therapy; however, one patient declined the proposed Teclistamab. A variety of systemic therapies were administered: 5 patients received anti-CD38 therapy + PIs, 3 received anti-CD38 + IMIDs, 3 received PIs + IMIDs and 3 received just IMIDs. Among these patients, 71% (n = 10) achieved both pain control and complete bone response following treatment. Eventually, 3 of these patients experienced biochemical relapse without bone involvement. The remaining 29% of patients (n = 4) did not achieve adequate pain control. Among these four patients, half (n = 2) showed stable bone disease and maintained stable disease as per IMWG response criteria, while the other half (n = 2) experienced progressive bone disease at 11 and 22 months, respectively. Of note, 2 patients developed signs of infection and 1 developed haematological toxicity, all occurring after one year of systemic therapy. The remaining patients did not experience relevant adverse events potentially related to radiotherapy. Overall, we observed a post-radiotherapy/chemotherapy PFS of 22 months. This outcome is encouraging in patients with extramedullary or extraskeletal disease. Radiotherapy provides a safe and rapid means of achieving bone pain palliation. While the observed PFS is promising in this subgroup, further investigation is needed to clarify the role of sequential radiotherapy and chemotherapy.