Therapeutic options in relapsed refractory (R/R) light-chain (AL) amyloidosis patients are limited. Given the encouraging results in t(11;14) multiple myeloma and the high prevalence of t(11;14) in AL amyloidosis, venetoclax is an attractive treatment option in this setting. We report here the results of a multi-center retrospective study on 26 R/R AL amyloidosis patients treated off-label with venetoclax. The median lines of therapy prior to venetoclax was 3.5 (range 1–7), and 88% of our cohort had t (11;14). Twenty-two patients (85%) were previously treated with daratumumab. The overall hematologic response rate was 88%, 35% achieved a CR, and 35% achieved VGPR. The median event-free survival was 25 months (m) (95% CI 9.7 m-not reached), and the median overall survival was 33 m (95% CI 25.9–39.2 m). Most of the patients in this cohort are in ongoing deep responses and continuing venetoclax therapy. The treatment was relatively safe. One patient died due to infection, and there were two grade 3 infections in our cohort. Tumor lysis syndrome (TLS) was not seen in any patient. Dose reductions were frequent but did not affect the efficacy. These promising results require confirmation in a randomized controlled trial.

Discontinuation of lenalidomide maintenance after autologous stem cell transplantation is a burning question within the multiple myeloma (MM) community, especially after the inclusion of minimal residual disease (MRD) in the disease response criteria. In this prospective study, we evaluated the conversion to MRD positivity, the treatment-free survival (TFS), and the progression-free survival (PFS) in 52 patients with MM who discontinued lenalidomide maintenance after achieving sustained bone marrow and imaging MRD negativity for 3 years. Patients who developed MRD positivity after lenalidomide discontinuation restarted lenalidomide maintenance at the same dose. The median follow-up from lenalidomide discontinuation was 3 years. Overall, 12 (23%) patients obtained MRD positivity and restarted lenalidomide maintenance. Only 4 (7.6%) patients progressed; 3 had a biochemical progression and 1 had a clinical progression. The overall median PFS was not reached, whereas the 7-year PFS from diagnosis was 90.2%. The 1-, 2-, and 3-year TFS rates were 93.9%, 91.6%, and 75.8%, respectively, whereas the 1-, 2-, and 3-year landmark PFS rates from maintenance discontinuation (study entrance) were 96.0%, 96.0%, and 92.9%, respectively. There were no statistically significant associations among age, sex, Second Revision International Staging System, type of induction therapy, and use of consolidation therapy and the effect outcomes of PFS and TFS. We conclude that maintenance discontinuation after 3 years of sustained marrow and imaging MRD negativity is associated with low rates of MRD conversion and progressive disease. Thus, in the era of modern antimyeloma treatments, a subgroup of patients may remain treatment free while in complete remission without jeopardizing disease response.

Infections remain a challenge during treatment of patients with multiple myeloma (MM) with anti–B-cell maturation antigen (BCMA) and anti–G protein-coupled receptor class C group 5 member D (GPRC5D) bispecific antibodies (bsAbs). However, the mechanism underlying different rates and severity of infections induced by the 2 bsAbs remains poorly understood. Single-cell RNA sequencing of bone marrow (BM) aspirates of 11 patients with MM and 8 healthy donors revealed BCMA expression on mature B cells and, surprisingly, in small pre-B cells within B-cell precursors. GPRC5D expression was restricted to malignant and less to normal plasma cells (PCs). Next-generation flow cytometry immune profiling showed that anti-BCMA bsAbs severely depleted BM mature B cells, from 4.9% to 0% (P< .001), and normal PCs, from 0.17% to <0.0002% (P< .001), during treatment of 62 patients with relapsed MM. This was observed throughout therapy. Additional flow cytometry (n = 31) and single-cell RNA sequencing studies (n = 8) demonstrated that, in contrast to anti-GPRC5D, anti-BCMA bsAbs also depleted immature and small pre-B cells. The MIcγ1 mouse model was used as a negative control of BCMA expression in all stages of the B-cell lineage, confirming no depletion of any B-cell subset after anti-BCMA treatment. In conclusion, we show that although GPRC5D bsAbs selectively target PCs, anti-BCMA bsAbs target both PCs and B cells from the small pre-B stage onward. Our study provides mechanistic insight into the increased infection risk with anti-BCMA therapy and supports individualized bsAb strategies in MM. Moreover, dual targeting of B cells and PCs may have therapeutic potential in other B-cell malignancies or autoimmune diseases.

COVID-19 vaccination leads to a less intense humoral response in patients with multiple myeloma (MM) compared with healthy individuals, whereas the SARS-CoV-2-specific immunity fades over time. The purpose of this study was to explore the kinetics of SARS-CoV-2 neutralizing antibodies (NAbs) in patients with MM after vaccination with the BNT162b2 mRNA vaccine, focusing on their response before (B4D) and at 1 month after the fourth vaccination (M1P4D). Overall, 201 patients with a median age of 67 years were included, whereas 114 (56.7%) were men. The median NAbs levels B4D were 80.0% (±3.5%) and at M1P4D they increased to a median value of 96.1% (±3.7%). The NAb values at M1P4D were similar to those at 1 month post the third dose and superior to all previous timepoints. At M1P4D, the NAbs levels of all the treatment groups increased, apart from the anti-BCMA group. A significant increase in median NAbs values was observed for those receiving CD38-based treatment (n = 43, from 71.0% B4D to 96.0% at M1P4D) and those who did not receive CD38- or BCMA-targeted therapy (n = 137, from 89.6% B4D to 96.3% at M1P4D). Regarding the patients under BCMA-based therapy (n = 21), there was no remarkable increase in NAbs values following the second booster shot (from 3.0% B4D to 4.0% at M1P4D). In conclusion, booster vaccination with the BNT162b2 results in a substantially improved humoral response against SARS-CoV-2 in patients with MM. Anti-BCMA treatment remains an adverse predictive factor for NAbs response; thus, tailored prevention measures should be considered for this patient subgroup.

Systemic AL amyloidosis is a rare complex hematological disorder caused by clonal plasma cells which produce amyloidogenic immunoglobulins. Outcome and prognosis is the combinatory result of the extent and pattern of organ involvement secondary to amyloid fibril deposition and the biology and burden of the underlying plasma cell clone. Prognosis, as assessed by overall survival, and early outcomes is determined by degree of cardiac dysfunction and current staging systems are based on biomarkers that reflect the degree of cardiac damage. The risk of progression to end-stage renal disease requiring dialysis is assessed by renal staging systems. Longer-term survival and response to treatment is affected by markers of the underlying plasma cell clone; the genetic background of the clonal disease as evaluated by interphase fluorescence in situ hybridization in particular has predictive value and may guide treatment selection. Free light chain assessment forms the basis of hematological response criteria and minimal residual disease as assessed by sensitive methods is gradually being incorporated into clinical practice. However, sensitive biomarkers that could aid in the early diagnosis and that could reflect all aspects of organ damage and disease biology are needed and efforts to identify them are continuous.

B-cell maturation antigen (BCMA) is a promising therapeutic target for multiple myeloma (MM). The aim of this study was to assess the effectiveness and tolerability of monotherapy with the conjugated anti-BCMA monoclonal antibody belantamab mafodotin in triple-class refractory patients with MM in real-world practice. Patients refractory to at least one proteasome inhibitor, one immunomodulatory drug, and one anti-CD38 monoclonal antibody received belantamab mafodotin at 2.5 mg/kg intravenously every 3 weeks. Overall, 27 patients with a median age of 65 years (range 41–81) were included. Of these, 52% were male and the median number of prior lines of treatment was 5 (4–10). The overall response rate (partial response or better) was 52%, whereas the disease control rate (stable disease or better) was 70%. The median progression-free survival (PFS) was 2 months (95%CI: 0–7), whereas the median PFS among the responders was 12 months (95%CI: 6–18). Regarding the toxicity profile, the most common toxicity was eye toxicity, in 44% of the patients. Keratopathy grade 2–3 was reported in 33.3% of the patients. In conclusion, belantamab mafodotin showed a safety and efficacy profile consistent with the results of the registrational study. Importantly, heavily pretreated patients who responded to treatment derived a substantial survival benefit.