Daratumumab: A Review in Combination Therapy for Transplant-Ineligible Newly Diagnosed Multiple Myeloma

Daratumumab and antineoplastic therapy versus antineoplastic therapy only for adults with newly diagnosed multiple myeloma ineligible for transplant

BACKGROUND

Multiple myeloma (MM) is a haematological malignancy that is characterised by proliferation of malignant plasma cells in the bone marrow. For adults ineligible to receive high-dose chemotherapy and autologous stem cell transplant, the recommended treatment combinations in first-line therapy generally consist of combinations of alkylating agents, immunomodulatory drugs, and proteasome inhibitors. Daratumumab is a CD38-targeting, human IgG1k monoclonal antibody recently developed and approved for the treatment of people diagnosed with MM. Multiple myeloma cells uniformly over-express CD-38, a 46-kDa type II transmembrane glycoprotein, making myeloma cells a specific target for daratumumab.

OBJECTIVES

To determine the benefits and harms of daratumumab in addition to antineoplastic therapy compared to antineoplastic therapy only for adults with newly diagnosed MM who are ineligible for transplant.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, EU Clinical Trials Register, ClinicalTrials.gov, WHO ICTRP, and conference proceedings from 2010 to September 2023.

SELECTION CRITERIA

We included randomised controlled trials that compared treatment with daratumumab added to antineoplastic therapy versus the same antineoplastic therapy alone in adult participants with a confirmed diagnosis of MM. We excluded quasi-randomised trials and trials with less than 80% adult participants, unless there were subgroup analyses of adults with MM.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the results of the search strategies for eligibility. We documented the process of study selection in a flowchart as recommended by the PRISMA statement. We evaluated the risk of bias in included studies with RoB 1 and assessed the certainty of the evidence using GRADE. We followed standard Cochrane methodological procedures.

MAIN RESULTS

We included four open-label, two-armed randomised controlled trials (34 publications) involving a total of 1783 participants. The ALCYONE, MAIA, and OCTANS trials were multicentre trials conducted worldwide in middle- and high-income countries. The AMaRC 03-16 trial was conducted in one high-income country, Australia. The mean age of participants was 69 to 74 years, and the proportion of female participants was between 40% and 54%. All trials evaluated antineoplastic therapies with or without daratumumab. In the ALCYONE and OCTANS trials, daratumumab was combined with bortezomib and melphalan-prednisone. In the AMaRC 03-16 study, it was combined with bortezomib, cyclophosphamide, and dexamethasone, and in the MAIA study, it was combined with lenalidomide and dexamethasone. None of the included studies was blinded (high risk of performance and detection bias). One study was published as abstract only, therefore the risk of bias for most criteria was unclear. The other three studies were published as full texts. Apart from blinding, the risk of bias was low for these studies. Overall survival Treatment with daratumumab probably increases overall survival when compared to the same treatment without daratumumab (hazard ratio (HR) 0.64, 95% confidence interval (CI) 0.53 to 0.76, 2 studies, 1443 participants, moderate-certainty evidence). After a follow-up period of 36 months, 695 per 1000 participants survived in the control group, whereas 792 per 1000 participants survived in the daratumumab group (95% CI 758 to 825). Progression-free survival Treatment with daratumumab probably increases progression-free survival when compared to treatment without daratumumab (HR 0.48, 95% CI 0.39 to 0.58, 3 studies, 1663 participants, moderate-certainty evidence). After a follow-up period of 24 months, progression-free survival was reached in 494 per 1000 participants in the control group versus 713 per 1000 participants in the daratumumab group (95% CI 664 to 760). Quality of life Treatment with daratumumab may result in a very small increase in quality of life after 12 months, evaluated on the EORTC QLQ-C30 global health status scale (GHS), when compared to treatment without daratumumab (mean difference 2.19, 95% CI -0.13 to 4.51, 3 studies, 1096 participants, low-certainty evidence). The scale is from 0 to 100, with a higher value indicating a better quality of life. On-study mortality Treatment with daratumumab probably decreases on-study mortality when compared to treatment without daratumumab (risk ratio (RR) 0.72, 95% CI 0.62 to 0.83, 3 studies, 1644 participants, moderate-certainty evidence). After the longest follow-up available (12 to 72 months), 366 per 1000 participants in the control group and 264 per 1000 participants in the daratumumab group died (95% CI 227 to 304). Serious adverse events Treatment with daratumumab probably increases serious adverse events when compared to treatment without daratumumab (RR 1.18, 95% CI 1.02 to 1.37, 3 studies, 1644 participants, moderate-certainty evidence). After the longest follow-up available (12 to 72 months), 505 per 1000 participants in the control group versus 596 per 1000 participants in the daratumumab group experienced serious adverse events (95% CI 515 to 692). Adverse events (Common Terminology Criteria for Adverse Events (CTCAE) grade ≥ 3) Treatment with daratumumab probably results in little to no difference in adverse events (CTCAE grade ≥ 3) when compared to treatment without daratumumab (RR 1.01, 95% CI 0.99 to 1.02, 3 studies, 1644 participants, moderate-certainty evidence). After the longest follow-up available (12 to 72 months), 953 per 1000 participants in the control group versus 963 per 1000 participants in the daratumumab group experienced adverse events (CTCAE grade ≥ 3) (95% CI 943 to 972). Treatment with daratumumab probably increases the risk of infections (CTCAE grade ≥ 3) when compared to treatment without daratumumab (RR 1.52, 95% CI 1.30 to 1.78, 3 studies, 1644 participants, moderate-certainty evidence). After the longest follow-up available (12 to 72 months), 224 per 1000 participants in the control group versus 340 per 1000 participants in the daratumumab group experienced infections (CTCAE grade ≥ 3) (95% CI 291 to 399).

AUTHORS' CONCLUSIONS

Overall analysis of four studies showed a potential benefit for daratumumab in terms of overall survival and progression-free survival and a slight potential benefit in quality of life. Participants treated with daratumumab probably experience increased serious adverse events. There were likely no differences between groups in adverse events (CTCAE grade ≥ 3); however, there are probably more infections (CTCAE grade ≥ 3) in participants treated with daratumumab. We identified six ongoing studies which might strengthen the certainty of evidence in a future update of this review.

Daratumumab-based immunotherapy vs. lenalidomide, bortezomib and dexamethasone in transplant-ineligible newly diagnosed multiple myeloma: a systemic review

Background

Since no randomized controlled trials have directly compared the efficacy and safety of immunotherapy with daratumumab versus lenalidomide/bortezomib/dexamethasone (RVD) in the frontline treatment of transplant-ineligible newly diagnosed multiple myeloma (TIE-NDMM), this study systematically reviewed the clinical studies regarding immunotherapy with daratumumab and RVD regimen in the treatment of TIE-NDMM to explore the optimization direction of the best first-line therapy.

Methods

The Cochrane Library, PubMed, Embase, and Web of Science databases were searched to collect studies on regimens containing daratumumab or RVD/RVD-lite for TIE-NDMM. Pooled and meta-analysis was then performed to compare the overall response rate (ORR), stringent complete remission (sCR) and CR rate, progression-free survival (PFS), overall survival (OS) and treatment-related discontinuation rate between daratumumab-containing immunotherapy regimen and RVD/RVD-lite regimen by using R 4.3.1 software.

Results

Nine prospective clinical trials were included, including 1795 TIE-NDMM or NDMM without intent for immediate ASCT. Among them, 938 patients were treated with daratumumab-based immunotherapy and 857 with RVD/RVD-lite regimens. Meta-analysis results showed that The daratumumab-based regimen showed a significantly higher CR/sCR rate than RVD/RVD-lite for TIE-NDMM (47% vs. 24%, P<0.01). The median PFS of the daratumumab-based and RVD/RVD-lite groups were 52.6 months and 35.1 months respectively (HR 0.77, 95%CI, 0.66-0.90). The median OS of both groups was not reached, and there were no significant differences in OS between the two groups (HR 1.03, 95%CI, 0.86-1.23). The therapy discontinuation rate led by adverse events was significantly higher in the RVD/RVD-lite group than in the daratumumab-based regimen group for the TIE-NDMM (16% vs. 7%, P=0.03).

Conclusion

This meta-analysis suggests that daratumumab-containing immunotherapy is superior to RVD in the depth of treatment efficacy, progression-free survival, and lower treatment-related discontinuation rates. Limited by the lack of head-to-head clinical trials, this conclusion needs to be verified by concurrent cohort studies.

CAR-T Therapy in Relapsed Refractory Multiple Myeloma

Multiple myeloma is a plasma cell neoplasm. The emergence of proteasome inhibitors, immunomodulatory drugs, and anti-CD38 monoclonal antibodies has improved the prognosis of multiple myeloma patients. However, some patients are still insensitive to conventional therapy or frequently relapse after remission. Chemotherapy based on proteasome inhibitors or immunomodulatory drugs is ineffective in controlling the progression of relapsed refractory multiple myeloma. No consensus has been reached on treating relapsed refractory multiple myeloma to date. Recently chimeric antigen receptor T cells therapy has shown promising results that could achieve rapid remissions of patients and improve their prognoses. Additionally, most patients in chimeric antigen receptor T cell clinical trials were triple-refractory multiple myeloma patients, indicating that chimeric antigen receptor T cell immunotherapy could overcome drug resistance to new drugs. Since single immunotherapies are prone to acquired resistance, combination immunotherapies based on emerging immunotherapies may solve this issue. Achieving complete remission and minimal residual disease negative status as soon as possible is beneficial to patients. This paper reviewed the main chimeric antigen receptor T cell products in relapsed refractory multiple myeloma, and it explained the drug resistance mechanism and improvement methods of chimeric antigen receptor T cells therapy. This review summarized the best beneficiaries of chimeric antigen receptor T cell therapy and the salvage treatment of disease recurrence after chimeric antigen receptor T cell therapy, providing some ideas for the clinical application of chimeric antigen receptor T cells.

Monoclonal antibodies used for the management of haematological disorders

INTRODUCTION

Monoclonal antibodies Ab (MoAb) are increasingly becoming part of therapeutic armamentarium for haematologists and haemato-oncologists. This review brings together commonly used antibodies in one place for brevity and novel understanding.

AREAS COVERED

Pubmed and Scopus databases were explored focusing on MoAb in clinical haematological practice. Emphasis was given to current review articles. The data base was searched from 1997 till present. 24 different antibodies, most of which are in use were discussed. Antibodies are used for diverse conditions i.e. malignant and benign haematological conditions, treatment at various phases of stem cell transplantation. These antibodies were used both alone or in combination with various chemotherapy, targeted small molecules or as immunoconjugates. Some of the side effect profiles of these antibodies were common and some were unique. Unusual infections or organ dysfunctions were noted. Improved function of antibodies by protein engineering is also advancing rapidly. Dosage, frequency and route of administration depended on the convenience and condition for which the antibody is used.

EXPERT OPINION

: MoAbs are increasingly used in haematology practice either alone or in combination with other types of therapy for improved out come in various haematological conditions.

Daratumumab: A Review in Newly Diagnosed Systemic Light Chain Amyloidosis

Subcutaneous daratumumab (DARZALEX^®) co-formulated with recombinant human hyaluronidase (DARZALEX FASPRO^®) is approved in several countries, including the USA and those of the EU, for use in combination with bortezomib, cyclophosphamide and dexamethasone for the treatment of adult patients with newly diagnosed light chain (AL) amyloidosis. Daratumumab is a CD38-targeting, human IgG1κ monoclonal antibody. In the pivotal phase III ANDROMEDA trial in adults with newly diagnosed systemic AL amyloidosis, the addition of daratumumab to bortezomib, cyclophosphamide and dexamethasone significantly increased the proportion of patients achieving a haematological complete response relative to bortezomib, cyclophosphamide and dexamethasone alone (primary endpoint). Daratumumab combination therapy produced rapid and deep haematological responses which were associated with improved major organ deterioration progression-free survival (PFS). The addition of daratumumab also led to higher cardiac and renal response rates at 6 and 12 months. Daratumumab had an acceptable tolerability profile when used as combination therapy. Therefore, daratumumab in combination with bortezomib, cyclophosphamide and dexamethasone represents an important emerging first-line treatment option for patients with systemic AL amyloidosis.

SAR442085, a novel anti-CD38 antibody with enhanced antitumor activity against multiple myeloma

Anti-CD38 monoclonal antibodies (mAbs) represent a breakthrough in the treatment of multiple myeloma (MM), yet some patients fail to respond or progress quickly with this therapy, highlighting the need for novel approaches. In this study we compared the preclinical efficacy of SAR442085, a next-generation anti-CD38 mAb with enhanced affinity for activating Fcγ receptors (FcγR), with first-generation anti-CD38 mAb daratumumab and isatuximab. In surface plasmon resonance and cellular binding assays, we found that SAR442085 had higher binding affinity than daratumumab and isatuximab for FcγRIIa (CD32a) and FcγRIIIa (CD16a). SAR442085 also exhibited better in vitro antibody-dependent cellular cytotoxicity (ADCC) against a panel of MM cells expressing variable CD38 receptor densities including MM patients' primary plasma cells. The enhanced ADCC of SAR442085 was confirmed using NK-92 cells bearing low and high affinity FcγRIIIa (CD16a)-158F/V variants. Using MM patients' primary bone marrow cells, we confirmed that SAR442085 had an increased ability to engage FcγRIIIa, resulting in higher natural killer (NK) cell activation and degranulation against primary plasma cells than preexisting Fc wild-type anti-CD38 mAbs. Finally, using huFcgR transgenic mice that express human Fcγ receptors under the control of their human regulatory elements, we demonstrated that SAR442085 had higher NK cell-dependent in vivo antitumor efficacy and better survival than daratumumab and isatuximab against EL4 thymoma or VK*MYC myeloma cells overexpressing human CD38. These results highlight the preclinical efficacy of SAR442085 and support the current evaluation of this next-generation anti-CD38 antibody in phase I clinical development in patients with relapsed/refractory MM.

Daratumumab Plus Carfilzomib, Lenalidomide, and Dexamethasone in Patients With Newly Diagnosed Multiple Myeloma

BACKGROUND

Combination therapy regimens containing a proteasome inhibitor, an immunomodulatory drug, and a steroid are an established standard of care for patients with newly diagnosed multiple myeloma (NDMM) regardless of transplant eligibility. Triplet regimens that include lenalidomide/dexamethasone combined with daratumumab or carfilzomib are highly active in multiple myeloma, including NDMM. The aim of this open-label, phase 1b study was to evaluate daratumumab in combination with carfilzomib, lenalidomide, and dexamethasone (D-KRd) in patients with NDMM.

PATIENTS AND METHODS

Patients (n = 22), regardless of transplant eligibility, received treatment with D-KRd for up to thirteen 28-day cycles or until autologous stem cell transplant. The first daratumumab dose was administered as a split infusion (8 mg/kg on days 1 and 2 of cycle 1). The primary end point was safety and tolerability.

RESULTS

A total of 10 patients discontinued treatment, most frequently because of elective autologous stem cell transplant (n = 8). The most common treatment-emergent adverse events (any grade; grade 3/4) were diarrhea (68%; 18%), lymphopenia (64%; 59%), cough (59%; 5%), and upper respiratory tract infection (55%; 0%). Stem cell collection was successful in most patients (91%). Daratumumab infusion-related reactions occurred in 9 (41%) patients, primarily during the first infusion, and were mild in severity (no grade 3/4 events). The best overall response rate was 95%, including 86% with a very good partial response or better and 67% with a complete response or better.

CONCLUSION

D-KRd was well tolerated, and encouraging efficacy results support further investigation of daratumumab-based quadruplet therapies for NDMM.

Treatment of Multiple Myeloma and the Role of Melphalan in the Era of Modern Therapies-Current Research and Clinical Approaches

Multiple myeloma (MM) accounts for 10% of all hematological malignancies, and it is the second most common hematological neoplasm for which chemotherapy is an important pharmacological treatment. High dose melphalan followed by autologous stem cell transplantation remains the standard of treatment for transplant-eligible patients with MM. In this review, we describe aspects of the pharmacokinetics and pharmacodynamics of melphalan therapy and related compounds. In addition, we describe the use of melphalan in innovative therapies for the treatment of MM, including the development of drug carriers to reduce systemic toxicity, combination therapy to improve the effectiveness of cancer therapy, and the chemical modification of the melphalan molecule to improve antitumor activity.

Flow cytometric evaluation of CD38 expression levels in the newly diagnosed T-cell acute lymphoblastic leukemia and the effect of chemotherapy on its expression in measurable residual disease, refractory disease and relapsed disease: an implication for anti-CD38 immunotherapy

Background

Recently, anti-CD38 monoclonal antibody (Mab) therapy has become a focus of attention as an additional/alternative option for many hematological neoplasms including T-cell acute lymphoblastic leukemia (T-ALL). It has been shown that antitumor efficacy of anti-CD38-Mab depends on the level of CD38 expression on tumor cells. Reports on CD38 expression in T-ALL are scarce, and data on the effect of cytotoxic chemotherapy on CD38 expression are limited to very few samples. Moreover, it lacks entirely in refractory disease and in adult T-ALL. We report the flow cytometric evaluation of CD38 expression in T-ALL blasts at diagnosis and the effect of cytotoxic chemotherapy on its expression in measurable residual disease (MRD), refractory disease (MRD≥5%), and relapsed disease in a large cohort of T-ALL.

Methods

The study included 347 samples (188 diagnostic, 100 MRD, 24 refractory and 35 relapse samples) from 196 (children: 85; adolescents/adults: 111) patients with T-ALL. CD38-positive blasts percentages (CD38-PBPs) and expression-intensity (mean fluorescent intensity, CD38-MFI) were studied using multicolor flow cytometry (MFC). MFC-based MRD was performed at the end-of-induction (EOI-MRD, day 30–35) and end-of-consolidation (EOC-MRD, day 78–85) subsequent follow-up (SFU-MRD) points.

Results

Patients were classified into early thymic precursor subtype of T-ALL (ETPALL, 54/188, 28.7%), and non-ETPALL (134/188, 71.3%). Of 188, EOI-MRD assessment was available in 152, EOC-MRD was available in 96 and SFU-MRD was available in 14 patients. CD38 was found positive in 97.9% (184/188) of diagnostic, 88.7% (110/124) MRD (including 24-refractory) and 82.9% (29/35) relapsed samples. Median (95% CI) of CD38-PBPs/MFI in diagnostic, MRD, refractory, and relapsed T-ALL samples were, respectively, 85.9% (82.10%–89.91%)/4.2 (3.88–4.47), 74.0% (58.87%–83.88%)/4.6 (3.67–6.81), 79.6% (65.25%–96.11%)/4.6 (3.33–8.47) and 85.2% (74.48%–93.01%)/5.6 (4.14–8.99). No significant difference was noted in CD38 expression between pediatric versus adult and patients with ETPALL versus non-ETPALL. No change was observed in CD38-MFI between diagnostic versus MRD and diagnostic versus relapsed paired samples. However, we noticed a mild drop in the CD38-PBPs in MRD samples compared with the diagnostic samples (p=0.016).

Conclusion

We report an in-depth analysis of CD38 expression in a large cohort of T-ALL at diagnosis, during chemotherapy, and at relapse. Our data demonstrated that CD38 is robustly expressed in T-ALL blasts with a little effect of cytotoxic chemotherapy making it a potentially effective target for antiCD38-Mab therapy.

Development of CAR-T cell therapies for multiple myeloma

Currently available data on chimeric antigen receptor (CAR)-T cell therapy has demonstrated efficacy and manageable toxicity in heavily pretreated multiple myeloma (MM) patients. The CAR-T field in MM is rapidly evolving with >50 currently ongoing clinical trials across all phases, different CAR-T design, or targets. Most of the CAR-T trials are performed in China and the United States, while European centers organize or participate in only a small fraction of current clinical investigations. Autologous CAR-T cell therapy against B cell maturation antigen shows the best evidence of efficacy so far but main issues remain to be addressed: duration of response, longer follow-up, prolonged cytopenia, patients who may benefit the most such as those with extramedullary disease, outcome prediction, and the integration of CAR-T cell therapy within the MM treatment paradigm. Other promising targets are, i.a.,: CD38, SLAMF7/CS1, or GPRC5D. Although no product has been approved to date, cost and production time for autologous products are expected to be the main obstacles for broad use, for which reason allogeneic CAR-T cells are currently explored. However, the inherent risk of graft-versus-host disease requires additional modification which still need to be validated. This review aims to present the current status of CAR-T cell therapy in MM with an overview on current targets, designs, and stages of CAR-T cell development. Main challenges to CAR-T cell therapy will be highlighted as well as strategies to structurally improve the CAR-T cell product, and thereby its efficacy and safety. The need for comparability of the most promising therapies will be emphasized to balance risks and benefits in an evidence-based but personalized approach to further improve outcome of patients with MM.

Daratumumab monotherapy in patients with heavily pretreated relapsed or refractory multiple myeloma: final results from the phase 2 GEN501 and SIRIUS trials

BACKGROUND

Daratumumab showed encouraging efficacy as monotherapy in patients with heavily pretreated multiple myeloma in the GEN501 and SIRIUS studies. Here we report a pooled, post-hoc final analysis of these two studies.

METHODS

GEN501 was an open-label, multicentre, phase 1-2, dose escalation and expansion study done in the Netherlands, the USA, Sweden, and Denmark. Eligible patients had multiple myeloma and had relapsed or were refractory to 2 or more previous lines of treatment that included a proteasome inhibitor or an immunomodulatory drug. SIRIUS was an open-label, multicentre, phase 2 study done in Canada, Spain, and the USA, in which eligible patients with multiple myeloma had received 3 or more previous lines of therapy, including a proteasome inhibitor or an immunomodulatory drug, or were double refractory. In both studies, eligible patients were aged 18 years or older and had an Eastern Cooperative Oncology Group performance status of 2 or less. In part 2 of GEN501, patients were given intravenous daratumumab 16 mg/kg once per week for 8 weeks, twice per month for 8 doses, and then once per month until disease progression. In part 2 of SIRIUS, patients received intravenous daratumumab 16 mg/kg once per week for 8 weeks, twice per month for 16 weeks, and once per month until disease progression. The primary endpoints (safety in GEN501 and overall response rate in SIRIUS) have previously been reported. These trials are registered on ClinicalTrials.gov, NCT00574288 (GEN501) and NCT01985126 (SIRIUS).

FINDINGS

Patients were enrolled in GEN501 from March 27, 2008, until May 30, 2014, and in SIRIUS from Sept 30, 2013, until May 5, 2014. The combined analysis included 148 patients who received daratumumab 16 mg/kg (42 patients in GEN501 part 2; 106 patients in SIRIUS), with a median follow-up of 36·6 months (IQR 34·5-38·2). Patients had received a median of 5 previous lines of therapy (IQR 4-7), and 128 (87%) of 148 patients were double refractory. The overall response rate was 30·4% (95% CI 23·1-38·5), including 20 (14%) of 148 patients with very good partial response or better (8·5-20·1) and seven (5%) patients reporting complete response or better (1·9-9·5). Among 45 responders, the median duration of response was 8·0 months (95% CI 6·5-14·7). Median overall survival was 20·5 months (95% CI 16·6-28·1), with a 3-year overall survival rate of 36·5% (28·4-44·6). The most common grade 3-4 treatment-emergent adverse events (TEAEs) were anaemia (grade 3, 26 [18%] of 148 patients; no grade 4 events) and thrombocytopenia (grade 3, 13 [9%] of 148 patients; grade 4, 8 [5%] of 148 patients). Serious drug-related TEAEs occurred in 13 (9%) of 148 patients. There were no treatment-related deaths.

INTERPRETATION

In this analysis, daratumumab 16 mg/kg monotherapy showed durable responses and there were no new safety concerns with longer follow-up.

FUNDING

Janssen Research & Development.

Roles of CD38 in the Immune Response to Infection

CD38 is a multifunctional protein widely expressed in cells from the immune system and as a soluble form in biological fluids. CD38 expression is up-regulated by an array of inflammatory mediators, and it is frequently used as a cell activation marker. Studies in animal models indicate that CD38 functional expression confers protection against infection by several bacterial and parasitic pathogens. In addition, infectious complications are associated with anti-CD38 immunotherapy. Although CD38 displays receptor and enzymatic activities that contribute to the establishment of an effective immune response, recent work raises the possibility that CD38 might also enhance the immunosuppressive potential of regulatory leukocytes. This review integrates the current knowledge on the diversity of functions mediated by CD38 in the host defense to infection.

CD38, a Receptor with Multifunctional Activities: From Modulatory Functions on Regulatory Cell Subsets and Extracellular Vesicles, to a Target for Therapeutic Strategies

CD38 is a multifunctional cell surface protein endowed with receptor/enzymatic functions. The protein is generally expressed at low/intermediate levels on hematological tissues and some solid tumors, scoring the highest levels on plasma cells (PC) and PC-derived neoplasia. CD38 was originally described as a receptor expressed by activated cells, mainly T lymphocytes, wherein it also regulates cell adhesion and cooperates in signal transduction mediated by major receptor complexes. Furthermore, CD38 metabolizes extracellular NAD+, generating ADPR and cyclic ADPR. This ecto-enzyme controls extra-cellular nucleotide homeostasis and intra-cellular calcium fluxes, stressing its relevance in multiple physiopathological conditions (infection, tumorigenesis and aging). In clinics, CD38 was adopted as a cell activation marker and in the diagnostic/staging of leukemias. Quantitative surface CD38 expression by multiple myeloma (MM) cells was the basic criterion used for therapeutic application of anti-CD38 monoclonal antibodies (mAbs). Anti-CD38 mAbs-mediated PC depletion in autoimmunity and organ transplants is currently under investigation. This review analyzes different aspects of CD38's role in regulatory cell populations and how these effects are obtained. Characterizing CD38 functional properties may widen the extension of therapeutic applications for anti-CD38 mAbs. The availability of therapeutic mAbs with different effects on CD38 enzymatic functions may be rapidly translated to immunotherapeutic strategies of cell immune defense.

Daratumumab, Bortezomib, and Dexamethasone Versus Bortezomib and Dexamethasone in Patients With Previously Treated Multiple Myeloma: Three-year Follow-up of CASTOR

BACKGROUND

In the phase III CASTOR study in relapsed or refractory multiple myeloma, daratumumab, bortezomib, and dexamethasone (D-Vd) demonstrated significant clinical benefit versus Vd alone. Outcomes after 40.0 months of median follow-up are discussed.

PATIENTS AND METHODS

Eligible patients had received ≥ 1 line of treatment and were administered bortezomib (1.3 mg/m²) and dexamethasone (20 mg) for 8 cycles with or without daratumumab (16 mg/kg) until disease progression.

RESULTS

Of 498 patients in the intent-to-treat (ITT) population (D-Vd, n = 251; Vd, n = 247), 47% had 1 prior line of treatment (1PL; D-Vd, n = 122; Vd, n = 113). Median progression-free survival (PFS) was significantly prolonged with D-Vd versus Vd in the ITT population (16.7 vs. 7.1 months; hazard ratio [HR], 0.31; 95% confidence interval [CI], 0.25-0.40; P < .0001) and the 1PL subgroup (27.0 vs. 7.9 months; HR, 0.22; 95% CI, 0.15-0.32; P < .0001). In lenalidomide-refractory patients, the median PFS was 7.8 versus 4.9 months (HR, 0.44; 95% CI, 0.28-0.68; P = .0002) for D-Vd (n = 60) versus Vd (n = 81). Minimal residual disease (MRD)-negativity rates (10^-5) were greater with D-Vd versus Vd (ITT: 14% vs. 2%; 1PL: 20% vs. 3%; both P < .0001). PFS2 was significantly prolonged with D-Vd versus Vd (ITT: HR, 0.48; 95% CI, 0.38-0.61; 1PL: HR, 0.35; 95% CI, 0.24-0.51; P < .0001). No new safety concerns were observed.

CONCLUSION

After 3 years, D-Vd maintained significant benefits in patients with relapsed or refractory multiple myeloma with a consistent safety profile. D-Vd provided the greatest benefit at first relapse and increased MRD-negativity rates.