This systematic review examines the available clinical data on CD34+ cell mobilization, collection, and engraftment in multiple myeloma patients treated with the anti-CD38 monoclonal antibodies daratumumab and isatuximab in clinical trials and in real life. Twenty-six clinical reports were published between 2019 and February 2024. Most studies documented lower circulating CD34+ cells after mobilization compared to controls, leading to higher plerixafor requirements. Although collection yields were significantly lower in approximately half of the studies, the collection target was achieved in similar proportions of daratumumab- and isatuximab-treated and nontreated patients, and access to autologous stem cell transplant (ASCT) was comparable. This could be explained by the retained efficacy of plerixafor in anti-CD38 monoclonal antibody-treated patients, while no chemotherapy-based or sparing mobilization protocol proved superior. Half of the studies reported slower hematopoietic reconstitution after ASCT in daratumumab- and isatuximab-treated patients, without an excess of infectious complications. While no direct effect on stem cells was observed in vitro, emerging evidence suggests possible dysregulation of CD34+ cell adhesion after daratumumab treatment. Overall, anti-CD38 monoclonal antibodies appear to interfere with CD34+ cell mobilization, without consistently leading to significant clinical consequences. Further research is needed to elucidate the underlying mechanisms and define optimal mobilization strategies in this patient population.

This post-marketing surveillance assessed the safety and effectiveness of isatuximab plus pomalidomide and dexamethasone (Isa-Pd) for relapsed or refractory multiple myeloma (RRMM) during real-world use in Japan. Data from 211 individuals with RRMM treated with Isa-Pd in Japan between October 2020 and October 2021 were collected, with follow-up for up to 12 months after initiation of Isa-Pd or until treatment discontinuation. The incidence of adverse drug reactions (ADRs), ADRs of special interest (infusion reactions, bone marrow suppression, infections, cardiac disorders, other ADRs of Grade ≥ 3), and serious ADRs was assessed. Best overall response and overall response rate (ORR) were determined. In the safety analysis set (n = 120), ADR incidence was 57.5%. Most ADRs were hematologic, and serious ADRs occurred in 28.3%. Bone marrow suppression occurred in 46.7% of participants (19.2% serious), infusion reactions in 18.3% (6.7% serious), infections in 11.7% (8.3% serious), and a serious cardiac disorder in one participant; other Grade ≥ 3 ADRs were reported in 3.3% (1.7% serious). In the effectiveness analysis set (n = 108), the most common best overall response was very good partial response (24.1%), and ORR was 51.9%. These findings support the safety and effectiveness of Isa-Pd for RRMM in real-life settings in Japan.

BACKGROUND: Isatuximab, an anti-CD38 antibody, has been widely used in treatments for patients with relapsed/refractory multiple myeloma (MM). Despite its high efficacy, not all patients achieve a lasting therapeutic response with isatuximab.
OBJECTIVE: We tried to identify biomarkers to predict the effectiveness of isatuximab by focusing on the host\'s immune status before treatment.
METHODS: We retrospectively analyzed the cases of 134 relapsed/refractory MM patients in the Kansai Myeloma Forum database who had received only a first isatuximab treatment.
RESULTS: Among the 134 patients, an isatuximab, pomalidomide and dexamethasone (Isa-PD) regimen, isatuximab, carfilzomib and dexamethasone (Isa-KD) regimen and isatuximab and/or dexamethasone (Isa-D) regimen were used in 112, 15 and 7 patients, respectively. The median age at treatment, number of prior treatment regimens, and progression-free survival (PFS) were 71, 6, and 6.54 months, respectively. Multivariate analysis showed that the PFS under the Isa-PD regimen was longer in patients with higher lymphocyte/monocyte ratio (LMR ≥ 4), fewer prior treatment regimens (< 6), and no use of prior daratumumab treatment. The OS under the Isa-PD regimen was longer in patients with higher white blood cell counts (WBC counts ≥ 3000/μL) and higher LMR. The PFS under the Isa-D regimen was longer in patients with fewer prior treatment regimens in univariate analysis, but no parameters were correlated with PFS/OS under the Isa-KD regimen.
CONCLUSIONS: We found that the patients with higher LMR (≥ 4) could obtain longer PFS and OS under the Isa-PD regimen. Other cohort studies of isatuximab treatment might be necessary to substantiate our results.

The limited availability of molecularly targeted low-molecular-weight imaging agents for monitoring multiple myeloma (MM)-targeted therapies has been a significant challenge in the field. In response, a first-in-class peptide-based radiotracer, [68Ga]Ga-AJ206, is developed that can be seamlessly integrated into the standard clinical workflow and is specifically designed to noninvasively quantify CD38 levels and pharmacodynamics by positron emission tomography (PET). A bicyclic peptide, AJ206, is synthesized and exhibits high affinity to CD38 (KD: 19.1 ± 0.99 × 10-9 m) by surface plasmon resonance. Further, [68Ga]Ga-AJ206-PET shows high contrast within 60 min and suitable absorbed dose estimates for clinical use. Additionally, [68Ga]Ga-AJ206 detects CD38 expression in cell line-derived xenografts, patient-derived xenografts (PDXs), and disseminated disease models in a manner consistent with flow cytometry and immunohistochemistry findings. Moreover, [68Ga]Ga-AJ206-PET successfully quantifies CD38 pharmacodynamics in PDXs, revealing increased CD38 expression in the tumor following all-trans retinoic acid (ATRA) therapy. In conclusion, [68Ga]Ga-AJ206 exhibits the salient features required for clinical translation, providing CD38-specific high-contrast images in multiple models of MM. [68Ga]Ga-AJ206-PET could be useful for quantifying total CD38 levels and pharmacodynamics during therapy to evaluate approved and new therapies in MM and other diseases with CD38 involvement.

Multiple myeloma (MM) is an incurable malignancy of the B-cell lineage. Remarkable progress has been made in the treatment of MM with anti-CD38 monoclonal antibodies such as daratumumab and isatuximab, which can kill MM cells by inducing complement-dependent cytotoxicity (CDC). We showed that the CDC efficacy of daratumumab and isatuximab is limited by membrane complement inhibitors, including CD46 and CD59, which are upregulated in MM cells. We recently developed a small recombinant protein, Ad35K++, which is capable of transiently removing CD46 from the cell surface. We also produced a peptide inhibitor of CD59 (rILYd4). In this study, we tested Ad35K++ and rILYd4 in combination with daratumumab and isatuximab in MM cells as well as in cells from two other B-cell malignancies. We showed that Ad35K++ and rILYd4 increased CDC triggered by daratumumab and isatuximab. The combination of both inhibitors had an additive effect in vitro in primary MM cells as well as in vivo in a mouse xenograft model of MM. Daratumumab and isatuximab treatment of MM lines (without Ad35K++ or rILYd4) resulted in the upregulation of CD46/CD59 and/or survival of CD46high/CD59high MM cells that escaped the second round of daratumumab and isatuximab treatment. The escape in the second treatment cycle was prevented by the pretreatment of cells with Ad35K++. Overall, our data demonstrate that Ad35K++ and rILYd4 are efficient co-therapeutics of daratumumab and isatuximab, specifically in multi-cycle treatment regimens, and could be used to improve treatment of multiple myeloma.

UNASSIGNED: The current study aims to evaluate the safety and efficacy of anti-CD38 monoclonal antibodies (mAbs) among patients with relapsed/refractory multiple myeloma (RRMM) through meta-analysis.
UNASSIGNED: As of June 2023, we searched PubMed, Web of Science, Embase and the Cochrane Library. Randomized controlled trials (RCTs) which compared the clinical outcomes of anti-CD38 mAbs plus immunomodulatory drugs (IMiDs) or proteasome inhibitors (PIs) plus dexamethasone and IMiDs (or PIs) and dexamethasone alone for RRMM patients were included. Efficacy outcomes were mainly evaluated with progression-free survival (PFS) and overall survival (OS). The safety was analyzed with hematologic and nonhematologic treatment-emergent adverse events (TEAEs). All results were pooled using hazard ratio (HR), relative risk (RR), and their 95% confidence interval (CI) and prediction interval (PI).
UNASSIGNED: This meta-analysis included 11 RCTs in total. Compared with IMiDs (or PIs) and dexamethasone alone, anti-CD38 mAbs in combination with IMiDs (or PIs) and dexamethasone significantly prolonged PFS (HR: 0.552, 95% CI = 0.461 to 0.659, 95% PI = 0.318 to 0.957) and OS (HR: 0.737, 95% CI = 0.657 to 0.827, 95% PI = 0.626 to 0.868) in patients with RRMM. Additionally, RRMM patients receiving anti-CD38 mAbs in combination with IMiDs (or PIs) and dexamethasone achieved higher rates of overall response (RR: 1.281, 95% CI = 1.144 to 1.434, 95% PI = 0.883 to 1.859), complete response or better (RR: 2.602, 95% CI = 1.977 to 3.424, 95% PI = 1.203 to 5.628), very good partial response (VGPR) or better (RR: 1.886, 95% CI = 1.532 to 2.322, 95% PI = 0.953 to 3.731), and minimum residual disease (MRD)-negative (RR: 4.147, 95% CI = 2.588 to 6.644, 95% PI = 1.056 to 16.283) than those receiving IMiDs (or PIs) and dexamethasone alone. For TEAEs, the rates of hematologic and nonhematologic TEAEs, including thrombocytopenia, neutropenia, upper respiratory tract infection (URTI), pneumonia, bronchitis, dyspnea, diarrhea, pyrexia, back pain, arthralgia, fatigue, insomnia, and hypertension, were higher in the anti-CD38 mAbs in combination with IMiDs (or PIs) and dexamethasone group than in the IMiDs (or PIs) and dexamethasone group.
UNASSIGNED: Our study showed that anti-CD38 mAbs in combination with IMiDs (or PIs) and dexamethasone improved PFS and OS, and achieved higher rates of overall response, complete response or better, VGPR or better, and MRD-negative, as well as higher rates of thrombocytopenia, neutropenia, URTI, pneumonia, bronchitis, dyspnea, diarrhea, pyrexia, back pain, arthralgia, fatigue, insomnia, and hypertension in RRMM patients.
UNASSIGNED: https://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023431071.

BACKGROUND: While quadruplet induction therapies deepen responses in newly diagnosed multiple myeloma patients, their impact on peripheral blood stem cell (PBSC) collection remains incompletely understood. This analysis aims to evaluate the effects of prolonged lenalidomide induction and isatuximab- or elotuzumab-containing quadruplet induction therapies on PBSC mobilization and collection.
METHODS: A total of 179 transplant-eligible patients with newly diagnosed MM treated at a single academic center were included. The patients were evaluated based on PBSC mobilization and collection parameters, including overall collection results, CD34+ cell levels in peripheral blood, leukapheresis (LP) delays, overall number of LP sessions, and the rate of rescue mobilization with plerixafor. The patients underwent four different induction regimens: Lenalidomide, bortezomib, and dexamethasone (RVd, six 21-day cycles, n = 44), isatuximab-RVd (six 21-day cycles, n = 35), RVd (four 21-day cycles, n = 51), or elotuzumab-RVd (four 21-day cycles, n = 49).
RESULTS: The patients\' characteristics were well balanced across the different groups. Collection failures, defined as the inability to collect three sufficient PBSC transplants, were rare (n = 3, 2%), with no occurrences in the isatuximab-RVd and elotuzumab-RVd groups. Intensified induction with six 21-day cycles of RVd did not negatively impact the overall number of collected PBSCs (9.7 × 106/kg bw versus 10.5 × 106/kg bw, p = 0.331) compared to four 21-day cycles of RVd. Plerixafor usage was more common after six cycles of RVd compared to four cycles (16% versus 8%). Addition of elotuzumab to RVd did not adversely affect overall PBSC collection (10.9 × 106/kg bw versus 10.5 × 106/kg bw, p = 0.915). Patients treated with isatuximab-RVd (six cycles) had lower numbers of collected stem cells compared to those receiving RVd (six cycles) induction (8.8 × 106/kg bw versus 9.7 × 106/kg bw, p = 0.801), without experiencing significant delays in LP or increased numbers of LP sessions in a multivariable logistic regression analysis. Plerixafor usage was more common after isatuximab plus RVd compared to RVd alone (34% versus 16%).
CONCLUSIONS: This study demonstrates that stem cell collection is feasible after prolonged induction with isatuximab-RVd without collection failures and might be further explored as induction therapy.
BACKGROUND: Patients were treated within the randomized phase III clinical trials GMMG-HD6 (NCT02495922, 24/06/2015) and GMMG-HD7 (NCT03617731, 24/07/2018). However, during stem cell mobilization and -collection, no study-specific therapeutic intervention was performed.

CD38 has been established as an important therapeutic target for multiple myeloma (MM), for which two CD38 antibodies are currently approved-daratumumab and isatuximab. CD38 is an ectoenzyme that degrades NAD and its precursors and is involved in the production of adenosine and other metabolites.
Among the various mechanisms by which CD38 antibodies can induce MM cell death is immunomodulation, including multiple pathways for CD38-mediated T-cell activation. Patients who respond to anti-CD38 targeting treatment experience more marked changes in T-cell expansion, activity, and clonality than nonresponders.
Resistance mechanisms that undermine the immunomodulatory effects of CD38-targeting therapies can be tumor intrinsic, such as the downregulation of CD38 surface expression and expression of complement inhibitor proteins, and immune microenvironment-related, such as changes to the natural killer (NK) cell numbers and function in the bone marrow niche. There are numerous strategies to overcome this resistance, which include identifying and targeting other therapeutic targets involved in, for example, adenosine production, the activation of NK cells or monocytes through immunomodulatory drugs and their combination with elotuzumab, or with bispecific T-cell engagers.

Lenalidomide-based regimens are commonly used for early relapse in patients with relapsed and/or refractory multiple myeloma (RRMM) receiving at least one prior line of therapy. In the absence of head-to-head comparison, matching-adjusted indirect comparison (MAIC) was conducted to demonstrate efficacy and safety of isatuximab+carfilzomib+dexamethasone (Isa-Kd) versus daratumumab + lenalidomide + dexamethasone (Dara-Rd) in RRMM.
Patient-level data from IKEMA trial (Isa-Kd, n = 179) were matched to aggregate data from POLLUX (Dara-Rd, n = 286). Hazard ratios (HR) and 95% confidence intervals (CI) for progression-free survival (PFS) and overall survival (OS) were generated by weighted Cox proportional hazard models. Odds ratios (OR), 95% CI, and p-value were calculated for ≥very good partial response (≥VGPR) and treatment-emergent adverse events (TEAEs).
After matching, no significant differences were observed between Isa-Kd and Dara-Rd in baseline characteristics except for patients with >3 prior lines (0.0% vs. 4.9%). Isa-Kd showed significantly better PFS (HR [95% CI]: 0.46 [0.24-0.86]; p = 0.0155), statistically non-significant improvement favoring Isa-Kd in OS (0.47 [0.20-1.09]; 0.0798), and ≥VGPR (OR [95% CI]: 1.53 [0.89-2.64]; p = 0.1252) than Dara-Rd. Odds of occurrence were significantly lower for some all-grade and grade 3/4 TEAEs with Isa-Kd than Dara-Rd.
These results support Isa-Kd as an efficacious treatment for early relapse in non-lenalidomide refractory patients.

UNASSIGNED: Patients with multiple myeloma are at higher risk for infections due to disease pathogenesis and administered therapies. The purpose of this study was to estimate the risk for any grade and severe infections associated with the use of anti-CD38 monoclonal antibodies in patients with multiple myeloma.
UNASSIGNED: We searched PubMed and EMBASE for randomized controlled trials (RCTs) that included patients with multiple myeloma who received CD38-targeting monoclonal antibody regimens and reported outcomes of infection and performed a random-effects meta-analysis to estimate the relative risk for infections.
UNASSIGNED: After screening 673 citations, we retrieved 17 studies providing data on 11 RCTs. Overall, the included reports evaluated 5316 patients (2797 in the intervention arm and 2519 in the control arm). The relative risk (RR) for both any grade or severe infections was 1.27 (95% CI, 1.17-1.37 and 1.14-1.41, respectively). The cumulative incidence of any grade infections for patients who received anti-CD38 agents was 77% (95% CI, 68%-86%), while for severe infections it was 28% (95% CI, 23%-34%). Patients treated with anti-CD38 agents had a 39% higher risk for any grade pneumonia (RR, 1.39; 95% CI, 1.12-1.72) and a 38% higher risk for severe pneumonia (RR, 1.38; 95% CI, 1.09-1.75). For upper respiratory tract infections, the relative risk was 1.51 and 1.71 for any grade and severe infections, respectively. Regarding varicella-zoster virus (VZV) reactivation, we found no evidence of increased risk (RR, 3.86; 95% CI, 0.66-22.50).
UNASSIGNED: Patients with multiple myeloma treated with regimens that included an anti-CD38 monoclonal antibody were at higher risk for any grade or severe infections without an associated higher mortality rate during the follow-up period of the retrieved studies. No evidence of increased risk for VZV reactivation was noted, but there was a significant association between CD38-targeting treatment and pneumonia risk. Increased surveillance for infections, development of effective prophylactic strategies, and studies with long follow-up are needed for patients with multiple myeloma treated with anti-CD38-based regimens.