Dreamm-5 Platform Trial: Belantamab Mafodotin (Belamaf) in Combination with Four Different Novel Agents in Patients with Relapsed/Refractory Multiple Myeloma (RRMM)

Introduction: Single-agent belamaf (GSK2857916), a B-cell maturation antigen–targeting antibody-drug conjugate, induced deep and durable responses in patients with RRMM, with a manageable safety profile with 13 months of follow-up (DREAMM-2; NCT03525678; Lonial et al, ASCO 2020, Poster 436). A platform trial design allows efficient evaluation of belamaf in combination with other anti-myeloma agents, such as a humanized wild-type IgG1 anti-OX40 agonist, an IgG4-inducible T-cell co-stimulator (ICOS) agonist, a gamma-secretase inhibitor, and a humanized programmed cell death (PD)-1 antagonist. The unique, multimodal mechanisms of action (MoAs) of belamaf, in combination with MoAs of these agents, has the potential to achieve synergistic effects in RRMM to further enhance anti-myeloma activity without compromising safety.

Methods: DREAMM-5 (NCT04126200) is a Phase I/II study that utilizes a master protocol with separate substudies comprised of sequential dose-exploration (DE) and cohort-expansion (CE) phases, to identify promising, effective belamaf combinations when compared with a shared single-agent belamaf control arm (CE phase only). The DE phase consists of multiple dosing cohorts with belamaf combinations in which patients are assigned to treatment slots by a predetermined algorithmic approach (N≤10 per cohort). A recommended Phase II dose (RP2D) for each combination treatment will be identified based on the safety and preliminary efficacy in the DE phase. At the end of the DE phase, an interim analysis of safety, pharmacokinetic, and efficacy data will also be performed for each substudy treatment combination to determine whether the combination should move forward at the RP2D to the CE phase. Patients in the CE phase (N≥35 per cohort) will be randomized to a substudy and within a substudy to either combination treatment or the belamaf monotherapy control arm; patients will also be stratified by number of prior therapies). Eligible patients will have RRMM and will have received ≥3 prior therapy lines, which includes a prior immunomodulatory agent, proteasome inhibitor, and anti-CD38 antibody; all patients will provide informed consent for participation. The primary objectives of the study are to identify the RP2D (DE phase) and the overall response rate (≥partial response, CE phase), along with safety and tolerability, for each combination treatment.

Substudies 1 (combination with GSK3174998, OX40 agonist antibody), 2 (combination with GSK3359609, ICOS agonist antibody), and 3 (combination with nirogacestat [PF-03084014; SpringWorks Therapeutics], gamma-secretase inhibitor) are currently open to enrollment. Substudy 4 (combination with dostarlimab; PD-1 antagonist antibody) is under review. Additional substudies will be explored based on scientific rationale and/or preclinical combination study results.

Funding: GSK (Study 208887); belamaf drug linker technology licensed from Seattle Genetics; belamaf monoclonal antibody produced using POTELLIGENT Technology licensed from BioWa; nirogacestat gamma-secretase inhibitor produced by and used in collaboration with SpringWorks Therapeutics.

Figure: DREAMM-5 study design