Selinexor, Bortezomib and Dexamethasone: An Effective Salvage Regimen for Heavily Pretreated Myeloma Patients

Real World Efficacy and Toxicity of Selinexor: Importance of Patient Characteristics, Dose Intensity and Post Progression Outcomes

BACKGOUND

Selinexor is an orally available selective inhibitor of exportin-1 that has offered a new treatment option in relapsed or refractory myeloma (RRMM) either in combination with dexamethasone (Sd) or with bortezomib and dexamethasone (SVd).

PATIENTS-METHODS

We evaluated the efficacy and toxicity of selinexor combinations in the real world, post progression therapies and their outcomes. The analysis included 44 patients with RRMM treated with Sd (N = 21, 48%) or SVd (N = 23, 52%).

RESULTS

On intent-to-treat, response rate (ORR) among all treated patients was 29.5% (13/44, of which CR: 2, VGPR: 3, PR:8); ORR was 35% for SVd and 24% for Sd. Median PFS was 3.0 months for all; 6.9 months for responders (≥PR),2.7 months for Sd and 3.4 months for SVd treated patients. In univariate analysis, serum albumin <3.5 g/dl and LDH >ULN were associated with worse PFS (P = .001 and P = .032, respectively).The OS of the whole cohort exceeded one year while serum albumin <3.5 gr/dl and LDH>ULN were associated with worse OS. After progression to Sd/SVd, 20 patients received further therapy; on ITT, the ORR was 40% (8/20) and the subsequent PFS was 3.4 months. The most common adverse events were fatigue, thrombocytopenia and nausea, while the most recorded grade 3 or 4 side effect was thrombocytopenia; 56% (25/44) of patients required dose reduction, however, this was not associated with inferior PFS.

CONCLUSION

In conclusion, selinexor-based therapy provides an additional treatment option in the real word setting and with appropriate dosing and toxicity management a subset of patients may have significant benefit.

Selinexor: Targeting a novel pathway in multiple myeloma

Selinexor is an orally bioavailable selective inhibitor of nuclear export compound that inhibits exportin-1 (XPO1), a novel therapeutic target that is overexpressed in multiple myeloma (MM) and is responsible for the transport of ∼220 nuclear proteins to the cytoplasm, including tumour suppressor proteins. Inhibition of this process has demonstrated substantial antimyeloma activity in preclinical studies, both alone and in combination with established MM therapeutics. Based on a clinical trial programme encompassing multiple combination regimens, selinexor-based therapy has been approved for the treatment of relapsed/refractory MM (RRMM), with selinexor-dexamethasone approved in the later-relapse setting for penta-refractory patients and selinexor-bortezomib-dexamethasone approved for patients who have received ≥1 prior therapy. Here, we provide a comprehensive review of the clinical data on selinexor-based regimens, including recent updates from the 2022 American Society of Hematology annual meeting, and summarise ongoing studies of this novel targeted agent in newly diagnosed MM and RRMM.