Ixazomib and daratumumab without dexamethasone (I-Dara) in elderly frail RRMM patients: A multicenter phase 2 study (IFM 2018-02) of the Intergroupe Francophone du Myelome (IFM).

8000 Background: Frail patients with multiple myeloma have an inferior outcome, especially in the relapse setting. This adverse prognosis is mainly related to a high discontinuation rate due to treatment (Tx) related adverse events. The aim of this phase 2 study is to evaluate efficacy and tolerability of Ixazomib-Daratumumab (I-Dara) 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-three patients (60%) were previously exposed to bortezomib, 37 (67%) were previously exposed to lenalidomide (Len) and 20 (36 %) 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 among 28 pts with ongoing Tx was 10 months [5-32] at data cutoff (February, 2)]. The median duration of Tx among 27 pts who stopped Tx was 6 months [0-18]: 18 had progressive disease. Nine patients died during the study: Daratumumab-related bronchospasm (D1C1); Ixazomib-related overdose (C2); sepsis (n = 4), progressive disease (n = 3). Regarding toxicity, 27 pts had a ≥grade 3 AE (49%). The most common grade 3-4 toxicities were thrombocytopenia (n = 9), other cytopenias (n = 4), infection (n = 8), hypertension (n = 3) and gastrointestinal disorders (n = 3). Fourteen out of 28 were SAE including 5 infections, 1 bronchospasm, 1 acute respiratory failure and 2 ixazomib overdoses. Overall response rate, including minimal response, was 86 % with a ≥VGPR rate of 32 % in the whole group. In Len refractory patients the ORR was 82 % and ≥VGPR 41%, in HR cytogenetic patients ORR was 85 % and ≥VGPR 46%. With a median follow-up of 11.6 months median PFS is 16 months and median OS NR (76% estimated at one year). 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. Clinical trial information: NCT03757221.