Daratumumab Bortezomib and Dexamethasone in Transplant Ineligible Newly Diagnosed Elderly Myeloma Patients - a Trial By Asian Myeloma Network

Abstract

Background: Transplant ineligible (TI) newly diagnosed Multiple Myeloma (NDMM) patients have inferior outcomes compared to that of a transplant population. This led to investigation of therapies with novel mechanisms of action to improve outcomes in this group. MAIA and ALCYONE studies have showed impressive outcomes in this group of patients. However, significant toxicities are a concern when delivering multiple anti-myeloma drugs concurrently in a continuous schedule in elderly patients. In this context, the efficacy and safety of Daratumumab, Bortezomib (finite) and dexamethasone in NDMM remains unknown. Aims: In this study, we investigated the combination of Daratumumab Bortezomib (in a finite schedule), and dexamethasone (DVd) followed by Daratumumab as maintenance in transplant ineligible TI NDMM patients from Asia (NCT03695744). Methods: This is a prospective, open-label, single-arm, phase 2 study of TI NDMM patients conducted by Asian Myeloma Network across three hospitals in Singapore. The primary end point was overall response rate. Secondary end points included progression free survival, overall survival, toxicity & safety, duration of response, minimal residual disease (MRD) and sustained MRD negativity. The study was approved by SingHealth Centralised IRB (CIRB No 2018/2730). Patients with confirmed diagnosis of MM, fulfilling inclusion / exclusion criteria were enrolled after signing informed consent. Patients received IV daratumumab 16mg/kg weekly in weeks 1-9, Q3 weekly from weeks 10 to 24 and Q4 weekly from week 25 onwards. Subcutaneous Bortezomib 1.3mg/m 2 and Dexamethasone 40mg (20mg for patients >75 years old) once weekly were administered for 9 months, followed by daratumumab maintenance until progression or toxicity. Response assessments were as per IMWG criteria and serial QOL data was also collected. Regular safety reviews were performed from recruitment of first patient by an independent committee. Here we report the protocol specified interim analysis of safety and efficacy end points. Results: From Oct 2019 till Sep 2021, we enrolled 27 patients. Median age was 74.3 years (range 70.5 to 79.2 years; 13/27 patients were >75years). 13 male and 14 were female patients. Ethnic distribution was 20 Chinese, 3 Malay, 3 Indian and 1 Others. ECOG performance status was 0 in 5(19%), 1 in 16(59%) and 2 in 6(22%) patients respectively. 11(41%) and 6(22%) patients belonged to Stage II and III ISS respectively. 14(52%) patients had CrCl <60ml/Min. 26(96%) patients experienced any grade adverse event with 17 experiencing a grade 3/4 event. Most common adverse events were infections, gastrointestinal disorders, peripheral neuropathy, and infusion related reactions. All grade and grade 3/4 AEs were relatively low, particularly haematological, given the absence of drugs known to cause significant myelotoxicity. Detailed AEs and SAEs are tabulated in Table 1. Three patients have died, of which one was due to a treatment related infection, while two others were unrelated (1 - suicide secondary to known mental illness, 1 - accidental fall & cervical spine injury). At data cut off (15 Oct 2022), 26 out of 27 patients had a response with 4(14.8%) sCR, 3 (11.1%) CR, 14 (51.9%) VGPR and 5 (18.5%) PR (1 missing assessment) giving an ORR of 96.3%. Median duration on Daratumumab was 16.3 mos and Bortezomib was 8 mos. 6 patients (22.2%) have experienced disease progression. With a median follow-up of 17.6 months, the 18-month progression free survival and overall survival were 65.4% & 89% respectively (median PFS and OS not estimable). Follow-up is on-going and we aim to report long-term survival, FISH/ cytogenetic & MRD results, toxicity and QOL data in future. Conclusion: DVd with Bortezomib in a finite schedule and Daratumumab maintenance achieved highly efficacious responses in elderly TI NDMM. Though this is a small study, toxicity rates here compare favorably to that noted in larger Phase 3 studies with quadruplets (Alcyone) and continuous triplet regimen as in the MAIA study. Whilst using novel agents like CD38 monoclonals upfront clearly improves responses and survival, minimizing toxicities without compromising efficacy by careful limitation of long-term concurrent exposure to multiple anti-myeloma drugs in an elderly population could help improve safety and quality of life. DVd could be an effective alternative in some elderly TI NDMM patients.