Phase 1b Study of Isatuximab in Combination With Bortezomib, Cyclophosphamide, and Dexamethasone in Newly Diagnosed, Transplant-ineligible Multiple Myeloma Patients

Anti-CD38 monoclonal antibody impairs CD34+ mobilization and affects clonogenic potential in multiple myeloma patients

BACKGROUND

Induction with daratumumab-based regimens followed by autologous stem cell transplantation is the current standard for newly diagnosed multiple myeloma (NDMM) patients eligible for intensive chemotherapy. However, concerns emerged regarding potential negative effects following daratumumab-based treatment on CD34+ mobilization. We here compared CD34+ mobilization and clonogenic potential between daratumumab and non-daratumumab based therapy without upfront plerixafor administration among patients affected by NDMM.

MATERIALS AND METHODS

Clinical, mobilization and clonogenic data from 41 consecutively enrolled NDMM patients were analyzed. Patients underwent collection of autologous CD34+ by apheresis at the ASST Grande Ospedale Metropolitano Niguarda, Milan, Italy, from January 2021 to March 2023. Clonogenicity analysis was performed on BFU-E and CFU-GM.

RESULTS

Seventy-five percent of daratumumab-treated patients underwent >1 apheresis, compared to 24% of non-daratumumab patients (p=0.0017). Daratumumab-treated patients had significantly lower CD34+ count (mean 38 vs 79/μL, respectively; p=0.0011), with a median CD34+ harvest of 3.98×106/kg (range 1.68-9.18) vs 6.87×106/kg (range 1.63-16.85) in non-daratumumab-treated (p=0.0006). In multivariate analysis the likelihood of undergoing >1 apheresis was significantly higher in older patients (OR 1.2, 95% CI 1-1.4, Z=2.10, p=0.03) and daratumumab-treated patients (OR 15, 95% CI 2.8-129, p=0.004). Moreover, daratumumab-based induction therapy demonstrated an independent negative association with BFU-E colony formation (p=0.0148), even when accounting for patient age and CD34+ levels.

DISCUSSION

Our findings underscore the impact of daratumumab-based treatment on CD34+ mobilization in a real-life, upfront plerixafor-free population of NDMM patients. Higher probability of requiring multiple apheresis occurred among daratumumab-treated patients. Interestingly, the observation that daratumumab might negatively impact BFU-E colony formation, independent of CD34+ cell count, offers novel biological perspectives. Appropriate strategies should be adopted by the Apheresis teams to mitigate these potential negative effects.

Recent Developments in Convenience of Administration of the Anti-CD38 Antibody Isatuximab: Subcutaneous Delivery and Fast Intravenous Infusion in Patients With Multiple Myeloma

Isatuximab-based combinations are among the accepted standard-of-care regimens for early-line treatment of patients with relapsed/refractory multiple myeloma (RRMM), based on the results of the Phase 3 ICARIA-MM and IKEMA trials. Further study findings have shown benefit with Isa-based combinations in patients with newly diagnosed MM, as reported from the randomized GMMG-HD7 and CONCEPT trials. Isa is currently approved in various countries for intravenous (IV) administration in patients with RRMM. A more convenient route of administration, such as subcutaneous (SC) injection, and faster IV infusion may substantially increase convenience of treatment. In this review, we outline evidence emerging from clinical trials that shows increasing clinical applicability of Isa across the MM therapeutic spectrum. We then review recent study results demonstrating that new treatment modalities, either SC Isa administration via an on-body delivery system (OBDS) or fast, 30-minute, fixed-volume IV infusion, are safe and effective, and enhance convenience of treatment with Isa for MM patients and healthcare providers. In the recently reported Phase 1b study, the safety profile and efficacy of Isa administered SC plus pomalidomide-dexamethasone were comparable to those observed with Isa administered IV plus pomalidomide-dexamethasone in the control arm and in the ICARIA-MM trial. Analysis of patient-reported outcomes indicated patient confidence in SC Isa administration and satisfaction with treatment delivery by OBDS. These findings point to SC administration as the preferred route for future treatment with Isa-based combinations, as well as to the use of fast, 30-minute IV infusions in settings where SC administration of Isa might not be available.