Bortezomib before and after high-dose therapy in myeloma: long-term results from the phase III HOVON-65/GMMG-HD4 trial.

The Dutch-Belgian Cooperative Trial Group for Hematology Oncology Group-65/German-speaking Myeloma Multicenter Group-HD4 (HOVON-65/GMMG-HD4) phase III trial compared bortezomib (BTZ) before and after high-dose melphalan and autologous stem cell transplantation (HDM, PAD arm) compared with classical cytotoxic agents prior and thalidomide after HDM (VAD arm) in multiple myeloma (MM) patients aged 18-65 years. Here, the long-term follow-up and data on second primary malignancies (SPM) are presented. After a median follow-up of 96 months, progression-free survival (censored at allogeneic transplantation, PFS) remained significantly prolonged in the PAD versus VAD arm (hazard ratio (HR)=0.76, 95% confidence interval (95% CI) of 0.65-0.89, P=0.001). Overall survival (OS) was similar in the PAD versus VAD arm (HR=0.89, 95% CI: 0.74-1.08, P=0.24). The incidence of SPM were similar between the two arms (7% each, P=0.73). The negative prognostic effects of the cytogenetic aberration deletion 17p13 (clone size ⩾10%) and renal impairment at baseline (serum creatinine >2 mg dl-1) on PFS and OS remained abrogated in the PAD but not VAD arm. OS from first relapse/progression was similar between the study arms (HR=1.02, P=0.85). In conclusion, the survival benefit with BTZ induction/maintenance compared with classical cytotoxic agents and thalidomide maintenance is maintained without an increased risk of SPM.

Natural history of relapsed myeloma, refractory to immunomodulatory drugs and proteasome inhibitors: a multicenter IMWG study.

Introduction of new myeloma therapies offers new options for patients refractory to immunomodulatory drugs (IMiDs) and proteasome inhibitors (PIs). In this multicenter study, patients with relapsed multiple myeloma, who have received at least three prior lines of therapy, are refractory to both an IMiD (lenalidomide or pomalidomide) and a PI (bortezomib or carfilzomib), and have been exposed to an alkylating agent were identified. The time patients met the above criteria was defined as time zero (T0). Five hundred and forty-three patients diagnosed between 2006 and 2014 were enrolled in this study. Median age at T0 was 62 years (range 31-87); 61% were males. The median duration between diagnosis and T0 was 3.1 years. The median number of lines of therapy before T0 was 4 (range 3-13). The median overall survival (OS) from T0 for the entire cohort was 13 (95% confidence interval (CI) 11, 15) months. At least one regimen recorded after T0 in 462 (85%) patients, with a median (95% CI) progression-free survival and OS from T0 of 5 (4, 6), and 15.2 (13, 17) months, respectively. The study provides the expected outcome of relapsed multiple myeloma that is refractory to a PI and an IMiD, a benchmark for comparison of new therapies being evaluated.

A phase I/II minor histocompatibility antigen-loaded dendritic cell vaccination trial to safely improve the efficacy of donor lymphocyte infusions in myeloma.

Allogeneic stem cell transplantation (allo-SCT) with or without donor lymphocyte infusions (DLI) is the only curative option for several hematological malignancies. Unfortunately, allo-SCT is often associated with GvHD, and patients often relapse. We therefore aim to improve the graft-versus-tumor effect, without increasing the risk of GvHD, by targeting hematopoietic lineage-restricted and tumor-associated minor histocompatibility antigens using peptide-loaded dendritic cell (DC) vaccinations. In the present multicenter study, we report the feasibility, safety and efficacy of this concept. We treated nine multiple myeloma patients with persistent or relapsed disease after allo-SCT and a previous DLI, with donor monocyte-derived mHag-peptide-loaded DC vaccinations combined with a second DLI. Vaccinations were well tolerated and no occurrence of GvHD was observed. In five out of nine patients, we were able to show the induction of mHag-specific CD8+ T cells in peripheral blood. Five out of nine patients, of which four developed mHag-specific T cells, showed stable disease (SD) for 3.5-10 months. This study shows that mHag-based donor monocyte-derived DC vaccination combined with DLI is safe, feasible and capable of inducing objective mHag-specific T-cell responses. Future research should focus on further improvement of the vaccination strategy, toward translating the observed T-cell responses into robust clinical responses.

Efficacy of host-dendritic cell vaccinations with or without minor histocompatibility antigen loading, combined with donor lymphocyte infusion in multiple myeloma patients.

Donor lymphocyte infusions (DLI) can induce durable remissions in multiple myeloma (MM) patients, but this occurs rather infrequently. As the graft-versus-tumor (GvT) effect of DLI depends on the presence of host-dendritic cells (DCs), we tested in a phase I/II trial whether the efficacy of DLI could be improved by simultaneous vaccination with host-DCs. We also analyzed the possibility of further improving the GvT effect by loading the DCs with peptides of mismatched hematopoietic cell-specific minor histocompatibility antigens (mHags). Fifteen MM patients not responding to a first DLI were included. Eleven patients could be treated with a second equivalent dose DLI combined with DC vaccinations, generated from host monocytes (moDC). For four patients, the DC products did not meet the quality criteria. In four of the treated patients the DCs were loaded with host mHag peptides. Toxicity was limited and no acute GvHD occurred. Most patients developed objective anti-host T-cell responses and in one patient a distinct mHag-specific T-cell response accompanied a temporary clinical response. These findings confirm that DLI combined with host-DC vaccination, either unloaded or loaded with mHag peptides, is feasible, safe and capable of inducing host-specific T-cell responses. The limited clinical effects may be improved by developing more immunogenic DC products or by combining this therapy with immune potentiating modalities like checkpoint inhibitors.

Clinical Implications of Complex Pharmacokinetics for Daratumumab Dose Regimen in Patients With Relapsed/Refractory Multiple Myeloma.

New therapeutic strategies are urgently needed to improve clinical outcomes in patients with multiple myeloma (MM). Daratumumab is a first-in-class, CD38 human immunoglobulin G1κ monoclonal antibody approved for treatment of relapsed or refractory MM. Identification of an appropriate dose regimen for daratumumab is challenging due to its target-mediated drug disposition, leading to time- and concentration-dependent pharmacokinetics. We describe a thorough evaluation of the recommended dose regimen for daratumumab in patients with relapsed or refractory MM.

A clinical update on the role of carfilzomib in the treatment of relapsed or refractory multiple myeloma.

Even though the prognosis of patients with multiple myeloma is continuing to improve, all patients eventually develop relapsed refractory disease. Several novel therapeutics have been developed in the last few years including the second-generation proteasome inhibitor carfilzomib which has been approved for patients with relapsed and refractory multiple myeloma in the United States since 2012. Recently data from several phase III studies have become available showing the promising efficacy of carfilzomib in combination with lenalidomide, which led to the renewed approval of carfilzomib in combination with lenalidomide and dexamethasone for relapsed myeloma in 2015. Furthermore carfilzomib showed superiority over bortezomib on both efficacy and toxicity profiles, especially a profoundly lower incidence in polyneuropathy. Carfilzomib has been shown to partially overcome the negative effects of high-risk cytogenetics. Promising combinations of carfilzomib with histone deacetylase (HDAC) inhibitors, pomalidomide and several other novel therapeutics have been presented in early studies. The optimal dosing regimen and sequence of treatment regimens remain important questions for the future.

Diagnosis, risk stratification and management of monoclonal gammopathy of undetermined significance and smoldering multiple myeloma.

Monoclonal gammopathy of undetermined significance (MGUS) is one of the most common premalignant disorders. IgG and IgA MGUS are precursor conditions of multiple myeloma (MM), whereas light-chain MGUS is a precursor condition of light-chain MM. Smoldering MM (SMM) is a precursor condition with higher tumor burden and higher risk of progression to symptomatic MM compared to MGUS. Assessment of the risk of progression of patients with asymptomatic monoclonal gammopathies is based on various factors including clonal burden, as well as biological characteristics, such as cytogenetic abnormalities and light-chain production. Several models have been constructed that are useful in daily practice for predicting risk of progression of MGUS or SMM. Importantly, the plasma cell clone may occasionally be responsible for severe organ damage through the production of a M-protein which deposits in tissues or has autoantibody activity. These disorders are rare and often require therapy directed at eradication of the underlying clone. Importantly, recent studies have shown that asymptomatic patients with a bone marrow plasma cell percentage ≥60%, free light-chain ratio ≥100, or >1 focal lesion on MRI (myeloma-defining events) have a 80% risk of developing symptomatic MM within 2 years. These patients are now considered to have MM requiring therapy, similar to patients with symptomatic disease. In this review, we provide an overview of the new diagnostic criteria of the monoclonal gammopathies and discuss risk of progression to active MM. We also provide recommendations for the management of patients with MGUS and SMM including risk-adapted follow-up.

Minor histocompatibility Ags: identification strategies, clinical results and translational perspectives.

Allogeneic stem cell transplantation (allo-SCT) and donor lymphocyte infusion are effective treatment modalities for various hematological malignancies. Their therapeutic effect, the graft-versus-tumor (GvT) effect, is based mainly on an alloimmune response of donor T cells directed at tumor cells, in which differences in the expression of minor histocompatibility Ags (mHags) on the cells of the patient and donor have a crucial role. However, these differences are also responsible for induction of sometimes detrimental GvHD. As relapse and development of GvHD pose major threats for a large proportion of allotransplanted patients, additional therapeutic strategies are required. To augment the GvT response without increasing the risk of GvHD, specific mHag-directed immunotherapeutic strategies have been developed. Over the past years, much effort has been put into the identification of therapeutically relevant mHags to enable these strategies for a substantial proportion of patients. Currently, the concept of mHag-directed immunotherapy is tested in clinical trials on feasibility, safety and efficacy. In this review, we will summarize the recent developments in mHag identification and the clinical data on mHag-specific immune responses and mHag-directed therapies in patients with hematological malignancies. Finally, we will outline the current challenges and future prospectives in the field.

Upregulation of CD38 expression on multiple myeloma cells by all-trans retinoic acid improves the efficacy of daratumumab.

Daratumumab is an anti-CD38 monoclonal antibody with lytic activity against multiple myeloma (MM) cells, including ADCC (antibody-dependent cellular cytotoxicity) and CDC (complement-dependent cytotoxicity). Owing to a marked heterogeneity of response to daratumumab therapy in MM, we investigated determinants of the sensitivity of MM cells toward daratumumab-mediated ADCC and CDC. In bone marrow samples from 144 MM patients, we observed no difference in daratumumab-mediated lysis between newly diagnosed or relapsed/refractory patients. However, we discovered, next to an expected effect of effector (natural killer cells/monocytes) to target (MM cells) ratio on ADCC, a significant association between CD38 expression and daratumumab-mediated ADCC (127 patients), as well as CDC (56 patients). Similarly, experiments with isogenic MM cell lines expressing different levels of CD38 revealed that the level of CD38 expression is an important determinant of daratumumab-mediated ADCC and CDC. Importantly, all-trans retinoic acid (ATRA) increased CD38 expression levels but also reduced expression of the complement-inhibitory proteins CD55 and CD59 in both cell lines and primary MM samples. This resulted in a significant enhancement of the activity of daratumumab in vitro and in a humanized MM mouse model as well. Our results provide the preclinical rationale for further evaluation of daratumumab combined with ATRA in MM patients.

The impact of circulating suppressor cells in multiple myeloma patients on clinical outcome of DLIs.

Allo-SCT followed by DLIs can establish long-term remissions in multiple myeloma (MM) patients. In many patients, however, the immunotherapeutic graft-versus-tumor (GVT) effect is moderate and not sustained, implying that immune suppression is mediated, among other factors, by regulatory T cells (Tregs) or myeloid-derived suppressor cells (MDSCs). Towards a better understanding and, eventually, manipulation of the immune-regulatory mechanisms in transplanted MM patients, we retrospectively sought a correlation between DLI outcome and circulating CD14(+) MDSCs, CD14(-) MDSCs and Tregs in 53 MM patients before their first DLI. We found significantly elevated frequencies of highly suppressive CD14(+) MDSCs, CD14(-) MDSCs and Tregs in pre-DLI samples from patients. Higher frequencies of Tregs, but not of MDSCs, were significantly associated with non-responsiveness to DLI. Furthermore, a lower frequency of Tregs predicted the development of chronic GVHD, which, in turn, displayed a high association with GVT. Elevated Treg frequencies before DLI were also associated with significantly shorter PFS and OS. Hence, our data reinforce the idea of active suppression of antitumor responses by Tregs in MM patients and therefore suggest that targeting patient Tregs before DLI may improve outcome of DLI.

Towards effective and safe immunotherapy after allogeneic stem cell transplantation: identification of hematopoietic-specific minor histocompatibility antigen UTA2-1.

Donor T cells directed at hematopoietic system-specific minor histocompatibility antigens (mHags) are considered important cellular tools to induce therapeutic graft-versus-tumor (GvT) effects with low risk of graft-versus-host disease after allogeneic stem cell transplantation. To enable the clinical evaluation of the concept of mHag-based immunotherapy and subsequent broad implementation, the identification of more hematopoietic mHags with broad applicability is imperative. Here we describe novel mHag UTA2-1 with ideal characteristics for this purpose. We identified this antigen using genome-wide zygosity-genotype correlation analysis of a mHag-specific CD8(+) cytotoxic T lymphocyte (CTL) clone derived from a multiple myeloma patient who achieved a long-lasting complete remission after donor lymphocyte infusion from an human leukocyte antigen (HLA)-matched sibling. UTA2-1 is a polymorphic peptide presented by the common HLA molecule HLA-A*02:01, which is encoded by the bi-allelic hematopoietic-specific gene C12orf35. Tetramer analyses demonstrated an expansion of UTA2-1-directed T cells in patient blood samples after several donor T-cell infusions that mediated clinical GvT responses. More importantly, UTA2-1-specific CTL effectively lysed mHag(+) hematopoietic cells, including patient myeloma cells, without affecting non-hematopoietic cells. Thus, with the capacity to induce relevant immunotherapeutic CTLs, it's HLA-A*02 restriction and equally balanced phenotype frequency, UTA2-1 is a highly valuable mHag to facilitate clinical application of mHag-based immunotherapy.

A gene expression signature for high-risk multiple myeloma.

There is a strong need to better predict the survival of patients with newly diagnosed multiple myeloma (MM). As gene expression profiles (GEPs) reflect the biology of MM in individual patients, we built a prognostic signature based on GEPs. GEPs obtained from newly diagnosed MM patients included in the HOVON65/GMMG-HD4 trial (n=290) were used as training data. Using this set, a prognostic signature of 92 genes (EMC-92-gene signature) was generated by supervised principal component analysis combined with simulated annealing. Performance of the EMC-92-gene signature was confirmed in independent validation sets of newly diagnosed (total therapy (TT)2, n=351; TT3, n=142; MRC-IX, n=247) and relapsed patients (APEX, n=264). In all the sets, patients defined as high-risk by the EMC-92-gene signature show a clearly reduced overall survival (OS) with a hazard ratio (HR) of 3.40 (95% confidence interval (CI): 2.19-5.29) for the TT2 study, 5.23 (95% CI: 2.46-11.13) for the TT3 study, 2.38 (95% CI: 1.65-3.43) for the MRC-IX study and 3.01 (95% CI: 2.06-4.39) for the APEX study (P<0.0001 in all studies). In multivariate analyses this signature was proven to be independent of the currently used prognostic factors. The EMC-92-gene signature is better or comparable to previously published signatures. This signature contributes to risk assessment in clinical trials and could provide a tool for treatment choices in high-risk MM patients.

Effect of stem cell transplantation for B-cell malignancies on disease course of associated polyneuropathy.

B cell dyscrasias are often refractory to medical treatments, and hematological stem cell therapy (SCT) may be warranted. It is not clear whether an associated polyneuropathy may also profit from SCT. In exceptional cases SCT has been tried in patients with monoclonal gammopathy and progressive polyneuropathy refractory to medical treatments. In a cohort of 225 patients with monoclonal gammopathy and polyneuropathy, we selected the six patients who underwent SCT and retrospectively examined the effects of SCT on the disease course of the associated polyneuropathy. In all patients except one, the indication for SCT was hemato-oncological (multiple myeloma in 4 patients and primary AL amyloidosis in 1). The remaining patient had an IgG monoclonal gammopathy of undetermined significance and a progressive and painful polyneuropathy for which she was treated with SCT. SCT led to improvement of motor scores and autonomic symptoms in one patient; three patients experienced improvement of neuropathic pain or sensory deficits but showed further progression of weakness. One patient showed no improvement at all. One patient died within 100 days after SCT. In conclusion, SCT as a treatment of refractory hematological malignancy may occasionally have a positive effect on the associated progressive polyneuropathy, although the benefits are very limited and the treatment-related mortality is high.

Monoclonal antibody-based therapy as a new treatment strategy in multiple myeloma.

The introduction of autologous stem cell transplantation combined with the introduction of immunomodulatory drugs (IMiDs) and proteasome inhibitors has significantly improved survival of multiple myeloma patients. However, ultimately the majority of patients will develop refractory disease, indicating the need for new treatment modalities. In preclinical and clinical studies, promising results have been obtained with several monoclonal antibodies (mAbs) targeting the myeloma tumor cell or the bone marrow microenvironment. The mechanisms underlying the therapeutic efficacy of these mAbs include direct induction of tumor cell apoptosis via inhibition or activation of target molecules, complement-dependent cytotoxicity and antibody-dependent cell-mediated cytotoxicity (ADCC). The capability of IMiDs to enhance ADCC and the modulation of various important signaling cascades in myeloma cells by both bortezomib and IMiDs forms the rationale to combine these novel agents with mAbs as new treatment strategies for myeloma patients. In this review, we will give an overview of various mAbs directly targeting myeloma tumor cells or indirectly via effects on the bone marrow microenvironment. Special focus will be on the combination of these mAbs with IMiDs or bortezomib.

Effect of thalidomide with melphalan and prednisone on health-related quality of life (HRQoL) in elderly patients with newly diagnosed multiple myeloma: a prospective analysis in a randomized trial.

Thalidomide with melphalan/prednisone (MPT) was defined as standard treatment in elderly patients with multiple myeloma (MM) based on five randomized trials. In one of these trials, HOVON49, a prospective health-related quality-of-life (HRQoL) study was initiated in order to assess the impact of thalidomide on QoL. Patients aged >65 years with newly diagnosed MM were randomized to receive melphalan plus prednisone (MP) or MPT, followed by thalidomide maintenance in the MPT arm. Two hundred eighty-four patients were included in this side study (MP, n=149; MPT n=135). HRQoL was assessed with the EORTC Core QoL Questionnaire (QLQ-C30) and the myeloma-specific module (QLQ-MY24) at baseline and at predetermined intervals during treatment. The QLQ-C30 subscales physical function (P=0.044) and constipation (P<0.001) showed an improvement during induction in favour of the MP arm. During thalidomide maintenance, the scores for the QLQ-MY24 paraesthesia became significantly higher in the MPT arm (P<0.001). The QLQ-C30 subscales pain (P=0.12), insomnia (P=0.068), appetite loss (P=0.074) and the QLQ-MY24 item sick (P=0.086) scored marginally better during thalidomide maintenance. The overall QoL-scale QLQ-C30-HRQoL showed a significant time trend towards more favourable mean values during protocol treatment without differences between MP and MPT. For the QLQ-C30 subscales emotional function and future perspectives, difference in favour of the MPT arm from the start of treatment was observed (P=0.018 and P=0.045, respectively) with no significant 'time × arm' interaction, indicating a persistent better patient perspective with MPT treatment. This study shows that the higher frequency of toxicity associated with MPT does not translate into a negative effect on HRQoL and that MPT holds a better patient perspective.

Prognostic factors and outcome in relapsed multiple myeloma after nonmyeloablative allo-SCT: a single center experience.

For relapsed multiple myeloma (MM) patients, allo-SCT is a possible treatment option, but recent data obtained using a nonmyeloablative (NMA) conditioning regimen are scarce. We retrospectively collected data from 38 relapsed MM patients who received a NMA allo-SCT from October 2001 to January 2008. In total, 18 patients (48%) were transplanted using a matched unrelated donor. The median follow-up is 2.3 years. In 16 patients (42%) the response improved and eight patients (21%) were rapidly progressive within 6 months after allo-SCT. In total, 15 patients (39%) were in CR after allo-SCT. The median PFS was 1.4 years (range, 0.1-4.9), and having a CR after allo-SCT or having chronic GVHD resulted in longer PFS. Median OS was 3.1 years (range, 0.2-7.2) and again having a CR after allo-SCT or chronic GVHD was associated with a better OS. Six patients (16%) have died from treatment-related diseases. These results indicate that NMA allo-SCT is a treatment option in relapsed MM patients and that results may be improved by strategies that enhance the CR rate after allo-SCT.

New developments in the treatment of patients with multiple myeloma.

Much progress has been made in the treatment of patients with multiple myeloma (MM). The introduction of new drugs such as thalidomide, bortezomib and lenalidomide has created more possibilities for patients than many years before. In addition, autologous peripheral blood stem cell transplantation after high-dose melphalan has become the standard of care for younger patients. Allogeneic stem cell transplantation is an experimental option for those younger patients with a human leucocyte antigen identical donor. Because of these rapid developments and many treatment options we need good quality clinical studies that can guide us in what to do in everyday practice. This review will focus on those studies that have changed the treatment guidelines for patients with MM.