P-253: REAL WORLD DATA OF SAFETY AND EFFICACY PROFILE OF DARATUMUMAB IN RELAPSED/REFRACTORY MULTIPLE MYELOMA PATIENTS: LOW GRADE RESPIRATORY INFECTIONS AND HIGH EFFICACY IN ALL TREATMENT LINES

Introduction: Duration of response in multiple myeloma (MM) patients has significantly ameliorated. Daratumumab is an approved treatment option in both first line and relapse-refractory (R/R) setting. The aim of our study is the efficacy and safety of daratumumab in R/R MM patients in daily practice.

Methods: In a cohort of 29 patients, daratumumab combination regimens were administered in 15/7/4/3 in 2nd/3rd/4th and 5th treatment line. Daratumumab in combination with lenalidomide and dexamethasone (DRd) was administered in 8 patients, with pomalidomide and dexamethasone (DPd) in 6 patients, with bortezomib and dexamethasone (DVd) in 4 patients, with Carfilzomib and dexamethasone (DKd) in one patient, with dexamethasone only in 7 patients. One patient received D-VRd. The cohort consisted of male/female: 18/11 patients with median age 63 (41-77) years old, IgG/IgA/IgD/FLC/non secretory=14/3/1/8/3. ISS at diagnosis was: Ι/ΙΙ/ΙΙI=6/12/11 patients. Plasmacytoma was detected in 4 patients, 1 with extraosseous location and 7 patients had elevated serum LDH levels. Conventional karyotype and FISH were available in 24 and 14 patients respectively. Twenty patients had normal karyotype, 1 hyperdiploid, 3 complex. Regarding FISH, 5/14 patients had del17p, 2/14 del1p/add1q, 1/14 t(4;14), 2/14 t(11;14). Overall, 24/29 (83%) experienced a pulmonary infection adverse event.

Results: Median PFS for patients in first relapse was not reached (3-49 months) and best response was CR/VGPR in 9/15 (60%) patients. All patients experienced a pulmonary infection adverse event, grade 3 requiring hospitalization in 2 patients and grade 2 in the rest. COVID-19 was detected in 7 patients. Nine patients developed neutropenia, grade 3/2/1=2/5/2 patients.
Median PFS for patients beyond first relapse was 15 (1-60) months and best response was VGPR or better in 5/14 (36%). Nine out of 14 (64%) patients experienced a pulmonary infection adverse event, grade 2= 8/9 and only one grade 3. COVID-19 was detected in 4/14 (28%) patients. None of the COVID infected patients had fatal outcome or required ICU admission. Seven out of fourteen patients developed neutropenia grade 2.

Conclusions: Daratumumab induced long and deep responses in all treatment lines. Even patients with multiple prior lines achieved durable responses. Although pulmonary infections were seen in the majority of patients, they were manageable with no fatalities.