Real-World Effectiveness and Safety of Belantamab Mafodotin Monotherapy in Triple-Class Refractory Multiple Myeloma

Belantamab mafodotin, lenalidomide and dexamethasone in transplant-ineligible patients with newly diagnosed multiple myeloma: part 1 results of a phase I/II study

Preclinical and clinical data demonstrate synergy between belantamab mafodotin (belamaf) and immunomodulatory drugs with limited overlapping toxicities. We investigated the safety and efficacy of belamaf with lenalidomide 25 mg on days 1-21 every 28 days and dexamethasone 40 mg weekly (belamaf-Rd) in transplant-ineligible patients with newly diagnosed multiple myeloma. Thirty-six patients (median age, 72.5 years) were randomized to receive belamaf at three different doses (2.5, 1.9, or 1.4 mg/kg) every 8 weeks. The dosing schedule was extended to every 12 weeks to mitigate ocular toxicity. Most common grade ≥3 adverse events were fatigue (n=21, 58.3%), rash (n=6, 16.7%), diarrhea (n=8, 22.2%) and COVID-19 (n=5, 13.9%). Grade 3-4 ocular adverse events, comprising visual acuity decline from baseline and/or keratopathy, were reported in 39/216 (18.1%), 33/244 (13.5%), and 26/207 (12.6%) ophthalmological assessments in the 2.5, 1.9, and 1.4 mg/kg cohorts, respectively. Importantly, grade 3-4 keratopathy was identified in 9/216 (4.2%), 1/244 (0.4%) and 1/207(0.5%) assessments. Most patients (32/36, 88.9%) were treated with the extended, every-12-week schedule, during which 40, 33 and 16 doses were withheld due to ocular adverse events in the 2.5, 1.9, and 1.4 mg/kg cohorts, respectively. Overall, the rates of very good partial response and better and complete response and better were 83.3% and 52.8%, respectively, without significant differences among cohorts. Over a median follow-up of 20.3 months no disease progression was reported; six patients discontinued treatment due to infection-related death (4 cases of COVID-19, 2 cases of pneumonia) and one patient withdrew consent. Based on the toxicity/efficacy balance, the recommended phase II dose was 1.9 mg/kg every 8 weeks, extended to every 12 weeks because of toxicity. In conclusion, Belamaf-Rd, with the extended schedule for belamaf, showed important clinical activity and a significant improvement of ocular adverse events with minimal impact on vision-related functioning in an elderly, non-transplant eligible population.

Belantamab mafodotin: an important treatment option for vulnerable patients with triple class exposed relapsed and/or refractory multiple myeloma

Not available.

Belantamab mafodotin in triple-refractory multiple myeloma patients: A retro-prospective observational study in Italy

Belantamab mafodotin is the first-in-class antibody-drug conjugates targeting B-cell maturation antigen to have demonstrated effectiveness in triple-class refractory multiple myeloma (TCR-MM) patients. We performed a retrospective study including 78 TCR patients, with at least four prior lines of therapy (LOTs), who received belantamab mafodotin within named patient program and expanded access program in Italy between 2020 and 2022. Median age was 65 years (range 42-86 years), ECOG performance status was ≥1 in 45% of patients. Overall, a clinical benefit was obtained in 36 out of 74 evaluable patients (49%), with 43%, 28%, and 13.5% achieving at least partial response, very good partial response, and complete response, respectively. After a median follow-up of 12 months (range 6-21 months), median duration of response, progression-free survival (PFS), and overall survival (OS) were 14, 5.5, and 12 months, respectively. Age >70 years, good performance status and response were associated with longer PFS and OS. Keratopathy occurred in 58% of patients (G3 2.5%), corneal symptoms in 32% (G3 1.2%) and a reduction in visual acuity in 14%. Grade 3 thrombocytopenia occurred in 9% of patients. Only 3% of patients discontinued belantamab mafodotin because of side effects. This real-life study demonstrated significant and durable responses of belantamab in TCR-MM patients with four prior LOTs, otherwise ineligible for novel immunotherapies.

Characteristics of isatuximab-derived interference in serum protein electrophoresis and immunofixation, and an absence of sustained in vivo interference due to belantamab mafodotin and denosumab

OBJECTIVES

Some therapeutic monoclonal antibodies, like daratumumab and elotuzumab, produce interfering monoclonal bands on serum protein electrophoresis (SPEP) and immunofixation electrophoresis (IFE). Whether other common therapeutic antibodies also produce interference has not been systematically evaluated.

DESIGN AND METHODS

SPEP/IFE from patients receiving isatuximab (48 patients), belantamab mafodotin (BM; 41), and denosumab (41) were retrospectively reviewed for therapeutic antibody interference. Cases exhibiting isatuximab interference were quantified and the maximum duration of isatuximab effect was evaluated. To characterize band position, neat human serum was spiked with BM or denosumab at supratherapeutic concentrations. Band migration patterns were compared on SPEP and IFE, with band position expressed relative to other constant protein fractions.

RESULTS

Isatuximab-induced IFE interference was common (81.3 % of evaluated patients) with a maximum observed duration of 8 weeks. 10.4 % of isatuximab patients had IgG kappa monoclonal gammopathies that co-migrated with the drug; this subset could benefit from HYDRASHIFT 2/4 isatuximab testing. 8.3 % of IFE cases were negative for an isatuximab band but showed large, endogenous M-spikes migrating elsewhere. All patients in this group expired within 1 year of this finding. We hypothesize that an inability to detect isatuximab in this setting corresponds to a large residual myeloma burden that reduces isatuximab serum concentration. This observation may serve as a negative prognostic factor. Spiking studies demonstrated that BM and denosumab produce interference in vitro, but sustained interference was not observed in >40 treated patients.

CONCLUSIONS

Therapeutic antibody interference in patients receiving isatuximab is common, and can persist for at least 8 weeks after administration. >10 % of patients receiving isatuximab may benefit from HYDRASHIFT testing post-therapy. In contrast, BM and denosumab fail to produce sustained interference in treated patients.

Treatment with low-dose, single-agent belantamab mafodotin is safe and provides long-term responses in heavily pretreated multiple myeloma patients

OBJECTIVES

To evaluate whether low-dose belantamab mafodotin (B-MAF) dosing results in lower toxicity and better overall outcome.

METHODS

We retrospectively evaluated nine consecutive patients treated with low-dose (1.9 mg/kg) B-MAF.

RESULTS

The median age was 70 years. Most patients were penta-refractory. Ocular toxicity was observed in 77.7%. Adverse events resulting in treatment delays were recorded in 9 out of 124 cycles being given. Overall response rate was 66% (6/9), and all responding patients achieved very good partial response or better. Within a median follow-up of 12 (range 0.5-13.8) months, median progression-free survival and overall survival were 14 (CI95% 6-22) and 20 (95%CI 0-41) months, respectively.

CONCLUSION

Low-dose B-MAF regimen showed high-efficacy and low-toxicity profile.