Ixazomib and daratumumab without dexamethasone (I-Dara) in elderly frail patients with RRMM: Results of the multicenter phase 2 study (IFM 2018-02) of the Intergroupe Francophone du Myélome (IFM).
Authors: Touzeau Cyrille , Leleu Xavier P , Mariette Clara , Manier Salomon , Brechignac Sabine , Vincent Laure , Hebraud Benjamin , Decaux Olivier , Schulmann Samantha , Lenoir Caroline , Godmer Pascal , Farge Agathe , Peyro Saint Paul Laure , Parienti Jean-Jacques , Macro Margaret 
Published: June 2023

8054

Background: Frailty is associated with inferior outcome in older myeloma patients, especially in the relapse setting.1,2 This adverse prognosis is mainly related to a high discontinuation rate for treatment (Tx) related adverse events (AE). Dexamethasone is responsible of a high rate of infections and metabolic AE. We present here the updated results from the phase 2 study I-Dara evaluating efficacy and tolerability of Ixazomib-Daratumumab without Dexamethasone in elderly frail patients with relapsed myeloma (RRMM) (NCT03757221). Methods: Ixa-Dara naïve RRMM patients received oral Ixazomib (4 mg: days 1, 8, 15), IV Daratumumab (16 mg/kg; days 1, 8, 15, 22, cycles 1-2; days 1, 15, cycles 3-6; days 1, cycles 7+) and IV Methylprednisolone before Daratumumab (100 mg at day 1, 8, cycle 1 and then 60 mg). They were enrolled after 1 or 2 prior therapy if their frailty score was ≥ 2 by IMWG score. The primary endpoint was ≥ very good partial response rate (VGPR) at one year. Secondary endpoints included ORR, PFS, OS & toxicity according to NCI-CTCAE version 5. Results: Sixty-three patients were screened and 55 enrolled between 03/2018 and 09/2021. Patient were at first (n = 36) or second relapse (n = 19). Thirty-five patients (64%) were previously exposed to bortezomib, 37 (67%) were previously exposed to lenalidomide (Len) and 23 (42 %) were refractory to Len. Median age was 82 (72-93). All patients had a frailty score ≥2 and 13 (24 %) had a 3 or 4 frailty score. In 41 patients ISS at diagnosis was stage I (n = 11), II (n = 18) or III (n = 12). Seventeen (36%) patients harbored high-risk (HR) cytogenetic, including t(4;14) (n = 8) or del17p (n = 10). The median duration of Tx (DOT) in 14 pts with ongoing Tx was 22 mos [min-max: 16-40] at data cutoff (January, 19)]. The median DOT in 41 pts who stopped Tx was 10 mos [min-max: 0-31]: 28 had progressive disease (PD). Fourteen patients died during the study: Daratumumab-related bronchospasm (D1C1); Ixazomib-related overdose (C2), sepsis (n = 3), pneumonia (n = 2), PD (n = 7). Regarding toxicity, 31 pts had a ≥grade 3 AE (55%). The most common grade 3-4 AE were thrombocytopenia (n = 10), other cytopenias (n = 5), anemia (n = 3), infection (n = 6), gastrointestinal disorders (n = 5) and hypertension (n = 3). The ≥VGPR rate is 32 % @ 1 year (34 % overall) with an ORR of 70% @ 1 year (74 % overall). In Len refractory patients the ≥VGPR rate is 40% @ 1 y and the ORR 70 %, in HR patients the ≥VGPR rate is 60 % and ORR 80%. With a median follow-up of 23.0 mos median PFS is 18.5 mos and median OS NR (75% OS estimated at 27.9 mos). Conclusions: In this elderly frail population Ixa-Dara is a feasible combination with favorable efficacy profile even in Len refractory and HR cytogenetic patients. Early toxicity remains a concern in this population eventhough more manageable with Dara SC. Late benefit is consistent with one third of patients still on treatment. Clinical trial information: NCT03757221 .