P891: ixazomib and daratumumab without dexamethasone (i-dara) in elderly frail rrmm patients: results of the multicenter phase 2 study (ifm 2018-02) of the intergroupe francophone du myélome (ifm).

Topic: 14. Myeloma and other monoclonal gammopathies - Clinical Background: Frailty is associated with inferior outcome in elderly 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. Aims: To evaluate efficacy and tolerability of Ixazomib and Daratumumab without Dexamethasone in elderly frail patients with relapsed myeloma (RRMM) (NCT03757221). We present here the updated results from the phase 2 study I-Dara 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). Summary/Conclusion: 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. 1Palumbo et al. JCO 2015, 2Facon et al. Leukemia 2020Keywords: dexamethasone, Myeloma, Elderly, Relapse