Higher Mortality in Patients With Diffuse Large B-cell Lymphoma Pre-Existing Arterial Hypertension-Real World Data of the Polish Lymphoma Research Group.

BACKGROUND: Arterial hypertension is mentioned as a risk factor in cardio-oncology. This study aimed to assess the long-term prognostic value of arterial hypertension (AH) in diffuse large B-cell lymphoma (DLBCL). METHODS: We analysed data collected by the Polish Lymphoma Research Group for the evaluation of the outcomes associated with the use of first-line rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone therapy in patients with DLBCL with coexisting AH. Patients with other cardiovascular comorbidities or premature chemotherapy discontinuation due to cardiovascular toxicity were excluded. RESULTS: Pre-existing AH was diagnosed in 65 of 232 patients with DLBCL (28%) included in the study, and was associated with significantly shorter overall survival values (p<0.00001). The rates of DLBCL recurrence, administration of second-, third-, or fourth-line chemotherapy, and lymphoma-related deaths were similar in patients with and those without AH. Cardiovascular deaths were significantly more frequently observed in patients with pre-existing AH (38.5% vs 3.6%, p<0.0001). In the univariate analysis, AH (p=0.000001), older age (p<0.000001), and diabetes (p=0.0065) were identified as significant predictors of all-cause mortality; however, cardiovascular mortality was associated with AH (p<0.000001), older age (p=0.000008), and dyslipidaemia (p=0.03). Multivariate analysis revealed AH as an age-independent significant predictor of all-cause (p=0.00045) and cardiovascular mortality (p<0.000001). CONCLUSION: In the long-term follow-up of patients with DLBCL, the role of AH, as an important age-independent predictor of premature cardiovascular mortality, was so strong that it may have value for use in close surveillance in cardio-oncology clinics.

Higher efficacy of intermediate dose cytarabine + G-CSF compared to cyclophosphamide + G-CSF in hematopoietic stem cell mobilization in patients with multiple myeloma.

BACKGROUND: There are several regimens used in hematopoietic stem cell (HSC) mobilization in multiple myeloma (MM). Cyclophosphamide (Cy) is one of the most commonly used agents, although it does not always result in collecting adequate number of CD34+ cells. Recently, cytarabine (Ara-C) has been proposed as potentially efficient and safe option. AIMS: Since the data regarding Ara-C in HSC mobilization is limited, the aim of our study was to compare retrospectively the efficiency and toxicity of G-CSF combined with either Ara-C or Cy in MM patients. MATERIALS & METHODS: Of a total of 89 patients, 43 received low or intermediate doses of Cy, and 46 were treated with 800 mg/m2 /day of Ara-C administered for two days. RESULTS: The mean peak of CD34+ cells/ul in peripheral blood was 132 (range, 84-202) in Ara-C and 51 (range, 29-69) in Cy cohort (p < 0.001). The median number of collected CD34+ cells (×106/kg) was 10.3 (range, 4.2-17.9) vs 4.5 (range, 2.7-8.9), respectively (p < 0.001). Mobilization failure was observed in one patient in Ara-C cohort (2%) and in 8 patients treated with Cy (19%) (p = 0.013). In the Ara-C group 98% of patients obtained more than 4×106 CD34+ cells/kg required for tandem transplantation. Moreover, we observed a trend toward increased paraprotein levels measured at transplant compared to before HSC mobilization in Ara-C cohort and significantly higher transfusion rates in that group. CONCLUSION: Our findings confirm higher HSC mobilization efficacy of Ara-C compared to Cy in MM patients. However, lower transfusions rate and better disease control of Cy may justify its use in some cases.

The efficacy and safety of pomalidomide in relapsed/refractory multiple myeloma in a "real-world" study: Polish Myeloma Group experience.

BACKGROUND: Patients with relapsed/refractory multiple myeloma (RRMM) have poor prognosis. Pomalidomide is an immunomodulatory compound that has demonstrated activity in MM patients with disease refractory to lenalidomide and bortezomib. OBJECTIVES: Participants of clinical trials are highly selected populations; therefore, the aim of this study was to present observations from real practice that might provide important information for practitioners. PATIENTS AND METHODS: We analyzed retrospectively 50 patients treated with pomalidomide in 12 Polish sites between 2014 and 2017. Median age was 63 years, median time since diagnosis 4.5 years and median number of prior regimens 4. RESULTS: The overall response rate was 39.1%. Median progression-free survival (PFS) and overall survival (OS) were 10.0 and 14.0 months, respectively. Previous treatment with immunomodulatory drugs, bortezomib or stem cell transplant had no impact on PFS and OS. Most frequent grade 3/4 treatment-emergent adverse events were hematologic (neutropenia 24.0%, thrombocytopenia 10.0%, anemia 8.0%). Most common grade 3/4 non-hematologic toxicities were respiratory tract infection (14.0%) and neuropathy (4.0%). CONCLUSIONS: This real-world data have confirmed that pomalidomide is an active drug in RRMM and support results of published clinical trials and other real-world studies.

Sinus bradycardia as a rare adverse event in patients receiving cyclosporine A after allogeneic hematopoietic stem cell transplantation.

Cyclosporine A (CSA) is a commonly used immunosuppressive agent for the prophylaxis of graft-versus-host disease following allogeneic hematopoietic stem cell transplantation (alloHSCT). While tachycardia is a known adverse effect of CSA, bradycardia remains a phenomenon rarely described in the literature. We conducted a retrospective evaluation of the incidence of bradycardia in patients after alloHSCT treated with CSA between January 2020 and February 2023 at our center. Out of 206 patients, sinus bradycardia following the administration of CSA was observed in 6 (2.9%), comprising 3 women and 3 men, with the median age of 55 years (range: 20-65). The underlying diseases were myeloid malignancies in 4 and aggressive lymphoma in 2 patients. The patients received grafts from a matched unrelated (n=5) or a haploidentical family donor (n=1) following various conditioning regimens. Coexisting cardiovascular disorders were found in 5 of the 6 patients. All patients experienced symptomatic bradycardia within 1-4 days (median 2 days) after CSA introduction, which persisted until CSA withdrawal. One patient required treatment with atropine. All patients continued their immunosuppressive therapy with tacrolimus, which was well-tolerated Our study indicates CSA as a causative factor of sinus bradycardia in a small percentage of alloHSCT patients receiving CSA as graft-versus host disease (GvHD) prophylaxis. Importantly, these patients did not experience any cardiac complications when switched to tacrolimus. Although further research on the effects of CSA on heart automatation is needed, our single-center experience can help prompt diagnosis and therapeutic intervention in daily clinical practice.

Pre-Transplant Dual-Energy X-ray Absorptiometry (DXA)-Derived Body Composition Measures as Predictors of Treatment Outcomes and Early Post-Transplant Complications in Patients with Multiple Myeloma (MM) Treated with Autologous Hematopoietic Stem Cell Transplantation (AutoHSCT).

Background/Objectives: Changes in muscle mass and bone density are common in multiple myeloma (MM) patients. Dual-energy X-ray absorptiometry (DXA) offers precise, non-invasive insights into a patient's physical condition before autologous stem cell transplantation (autoHSCT). This study examines how pre-transplant body composition impacts treatment outcomes and early complications in MM patients undergoing autoHSCT. Methods: This study is a single-center, retrospective analysis of patients with MM who were treated with first or second autoHSCT and underwent DXA pre-transplant between 11 August 2019 and 12 June 2024. Results: We conducted a study of pre-transplant body composition in 127 patients with MM. Among them, 108 (85%) qualified for first autoHSCT, while 19 (15%) qualified for a second. The median age of the patients was 64 years (range 50-73). In the Cox proportional hazards regression conducted in the group of women, Total Body %Fat was a statistically significant predictor for progression-free survival (PFS) (HR = 0.07, 95% CI = 0.01,0.6, p = 0.0157). In the Mann-Whitney U test conducted on males, Lean Mass/Height2 and Appen. Lean Height2 were statistically significant predictors of early infections after autoHSCT (Z = 1.98, p = 0.0473 and Z = 2.32, p = 0.0204, respectively). In males, Fat Mass/Height2 was a significant predictor of non-infectious toxicity related to treatment (Z = -1.98, p = 0.0476). Conclusions: In women, higher levels of adipose tissue initially appear to exert a protective effect; however, this benefit diminishes over time, with greater fat mass eventually correlating with an increased risk of disease progression. In men, muscle mass has been identified as a significant predictor of early infection risk post-autoHSCT. Furthermore, our findings indicate that an increased amount of adipose tissue in men is statistically associated with a higher risk of non-infectious treatment-related toxicity. These conclusions highlight the critical need for further investigation into the role of body composition.

MICB Genetic Variants and Its Protein Soluble Level Are Associated with the Risk of Chronic GvHD and CMV Infection after Allogeneic HSCT.

The aim of the present study was to determine the associations between the MICB genetic variability and the expression and the risk of development of post-transplant complications after allogeneic hematopoietic stem cell transplantation (HSCT). HSCT recipients and their donors were genotyped for two MICB polymorphisms (rs1065075, rs3828903). Moreover, the expression of a soluble form of MICB was determined in the recipients' serum samples after transplantation using the Luminex assay. Our results revealed a favorable role of the MICB rs1065075 G allele. Recipients with donors carrying this genetic variant were less prone to developing chronic graft-versus-host disease (cGvHD) when compared to recipients without any symptoms of this disease (41.41% vs. 65.38%, p = 0.046). Moreover, the MICB rs1065075 G allele was associated with a lower incidence of cytomegalovirus (CMV) reactivation, both as a donor (p = 0.015) and as a recipient allele (p = 0.039). The MICB rs1065075 G variant was also found to be associated with decreased serum soluble MICB (sMICB) levels, whereas serum sMICB levels were significantly higher in recipients diagnosed with CMV infection (p = 0.0386) and cGvHD (p = 0.0008) compared to recipients without those complications. A protective role of the G allele was also observed for the rs3828903 polymorphism, as it was more frequently detected among donors of recipients without cGvHD (89.90% vs. 69.23%; p = 0.013). MICB genetic variants, as well as serum levels of sMICB, may serve as prognostic factors for the risk of developing cGvHD and CMV infection after allogeneic HSCT.

Soluble MICA concentrations and genetic variability of MICA and its NKG2D receptor as factors affecting Graft-versus-Host Disease development after allogeneic haematopoietic stem cell transplantation.

Despite new treatment strategies, graft-versus-host disease (GvHD) remains a formidable complication after allogeneic hematopoietic stem cell transplantation (HSCT). This study aimed to investigate the impact of polymorphisms and expression of MICA and NKG2D receptor on the development of GvHD in allogeneic HSCT recipients. Soluble MICA (sMICA) concentration was measured in serum collected 30 days after transplantation and the genetic variability of MICA and NKG2D genes was evaluated. The frequency of NKG2D+NK cells was determined by flow cytometry before and (21, 30, 60 and 90 days) after transplantation. Recipients with acute GvHD grades II-IV carried the NKG2D rs1049174 C allele more frequently than controls or patients with no or mild disease. Patients with chronic GvHD had higher frequency of NKG2D expressing NK cells posttransplant, reflecting increased activity of their NK cells. Although no direct relationship between MICA SNPs and GvHD were observed, the presence of MICA rs1051792 GG genotype correlated with elevated sMICA levels and increased serum level of sMICA was associated with higher risk of chronic GvHD. Our findings suggest that sMICA concentration may serve as a potential biomarker for chronic GvHD and emphasize the impact of genetic variability of NKG2D and its surface expression on the HSCT outcome.

Stem Cell Mobilization Performed with Different Doses of Cytarabine in Plasma Cell Myeloma Patients Relapsing after Previous Autologous Hematopoietic Cell Transplantation-A Multicenter Report by the Polish Myeloma Study Group.

Salvage autologous hematopoietic cell transplantation (auto-HCT) may be used to treat relapse of plasma cell myeloma occurring after previous auto-HCT. When an insufficient number of hematopoietic stem cells have been stored from the initial harvest, remobilization is necessary. Here, we aimed to analyze the efficacy and safety of different doses of cytarabine (total 800 vs. 1600 vs. 2400 mg/m2) for remobilization. Sixty-five patients, 55% male, with a median age at remobilization 63 years, were included. Remobilization was performed with cytarabine_800 in 7, cytarabine_1600 in 36, and cytarabine_2400 in 22 patients. Plerixafor rescue was used in 25% of patients receiving cytarabine_1600 and 27% of those receiving cytarabine_2400. Patients administered cytarabine_800 were not rescued with plerixafor. Remobilization was successful in 80% of patients (57% cytarabine_800; 86% cytarabine_1600; 77% cytarabine_2400; p = 0.199). The yield of collected CD34+ cells did not differ between the different cytarabine doses (p = 0.495). Patients receiving cytarabine_2400 were at the highest risk of developing severe cytopenias, requiring blood product support, or having blood-stream infections. One patient died of septic shock after cytarabine_2400. In summary, remobilization with cytarabine is feasible in most patients. All doses of cytarabine allow for successful remobilization. Cytarabine_2400 is associated with higher toxicity; therefore, lower doses (800 or 1600 mg/m2) seem to be preferable.

Differential expression of miRNAs from extracellular vesicles in chronic graft-versus-host disease: A preliminary study.

BACKGROUND: Chronic graft-versus-host disease (cGvHD) is a complex disorder that typically manifests after allogeneic hematopoietic stem cell transplantation (HSCT). It is a major cause of non-relapse mortality, which makes finding biomarkers associated with its occurrence a priority. Recent studies increasingly indicate that microRNAs (miRNAs, short regulatory RNA molecules) can be used as biomarkers of various disorders. They can circulate in patients' bodies encapsulated within extracellular vesicles (EVs). OBJECTIVES: To identify miRNAs associated with the occurrence of cGvHD in EVs isolated from the plasma of patients after allogeneic HSCT. MATERIAL AND METHODS: We performed global miRNA expression profiling in a pilot cohort of 3 cGvHD cases and 4 non-cGvHD patients without disease symptoms 90 days after the transplantation (control group). RESULTS: The 2 groups were naturally clustered according to their miRNA profiles using unsupervised hierarchical clustering analysis. We identified 3 miRNAs that were differentially expressed in the cGvHD patients compared to the non-cGvHD patients. The levels of hsa-miR-630 and hsa-miR-374b-5p were lower in the cGvHD patients: 4.1-fold (p = 0.002) and 2.7-fold (p = 0.044), respectively. In contrast, the levels of hsa-miR-29c-3p were 5.8-fold higher (p = 0.004). CONCLUSIONS: Our results suggest that miRNA profiles from plasma EVs may act as markers of cGvHD onset.

Significance of HLA-E and its two NKG2 receptors in development of complications after allogeneic transplantation of hematopoietic stem cells.

Transplantation of hematopoietic stem cells (HSCT) is a procedure commonly used in treatment of various haematological disorders which is associated with significantly improved survival rates. However, one of its drawbacks is the possibility of development of post-transplant complications, including acute and chronic graft-versus-host disease (GvHD) or CMV infection. Various studies suggested that NK cells and their receptors may affect the transplant outcome. In the present study, patients and donors were found to significantly differ in the distribution of the NKG2A rs7301582 genetic variants - recipients carried the C allele more often than their donors (0.975 vs 0.865, p<0.0001). Increased soluble HLA-E (sHLA-E) levels detected in recipients' serum 30 days after transplantation seemed to play a prognostic and protective role. It was observed that recipients with higher sHLA-E levels were less prone to chronic GvHD (11.65 vs 6.33 pg/mL, p=0.033) or more severe acute GvHD grades II-IV (11.07 vs 8.04 pg/mL, p=0.081). Our results also showed an unfavourable role of HLA-E donor-recipient genetic incompatibility in CMV infection development after transplantation (OR=5.92, p=0.014). Frequencies of NK cells (both CD56dim and CD56bright) expressing NKG2C were elevated in recipients who developed CMV, especially 30 and 90 days post-transplantation (p<0.03). Percentages of NKG2C+ NK cells lacking NKG2A expression were also increased in these patients. Moreover, recipients carrying a NKG2C deletion characterized with decreased frequency of NKG2C+ NK cells (p<0.05). Our study confirms the importance of NK cells in the development of post-transplant complications and highlights the effect of HLA-E and NKG2C genetic variants, sHLA-E serum concentration, as well as NKG2C surface expression on transplant outcome.

Immunophenotypic Characteristics of Bone Marrow Microenvironment Cellular Composition at the Biochemical Progression of Multiple Myeloma.

Multiple myeloma (MM) relapses are inevitable in the majority of patients, and in addition to genetic changes in the MM clone, the immune profile of the bone marrow (BM) plays a key role in this process. Biochemical progression or relapse (BR) precedes clinical relapse in a significant proportion of patients with MM. In the present study, we used flow cytometry to assess the cellular composition of the BM microenvironment in MM patients with confirmed BR. Fifteen distinct cells subsets in the BM were evaluated with the panel of antibodies used routinely for MRD monitoring in MM in 52 patients with MM (MRD-negative n = 20, BR n = 20, and clinically relapsed MM, RMM n = 12). The median percentage of MM cells detected in BR patients was 0.90% versus not detectable in MRD-negative patients and of 3.0% in RMM cohort. Compared to the MRD-negative group, BR status was associated with an increase in the percentage of lymphoid subpopulations, including memory B cells (p = 0.003), CD27+T cells (p = 0.002), and NK/NKT cells (p < 0.001). Moreover, a decrease in B-cell precursors (p < 0.001) and neutrophils (p = 0.006) was observed. There were no significant differences in the composition of the BM cell subpopulations between the BR and RMM groups. Our results indicate the involvement of B-, T-, and NK cells in the process of losing immune surveillance over the MM clone that leads to relapse. It can be speculated that similar studies of a larger cohort of BR patients can potentially identify a group of patients for which an early treatment intervention would be beneficial.

Two Doses of BNT162b2 mRNA Vaccine in Patients after Hematopoietic Stem Cell Transplantation: Humoral Response and Serological Conversion Predictors.

Vaccination against SARS-CoV-2 is currently the best tool in the fight against the COVID-19 pandemic. However, there are limited data on its efficacy and safety after hematopoietic stem cell transplantation (HCT). We present the results of a prospective analysis of the humoral response to two doses of BNT162b2 mRNA vaccine in 93 adult patients, including 29 after autologous HCT (autoHCT) and 64 after allogeneic HCT (alloHCT). Positive anti-SARS-CoV-2 antibodies were detected before vaccination in 25% of patients despite a negative medical history of COVID-19. Seroconversion after vaccination was achieved in 89% of patients after alloHCT and in 96% after autoHCT, without grade 3/4 adverse events. Post-vaccination anti-SARS-CoV-2 antibody level correlated with the time from transplant and absolute B-cell count at the vaccination. In univariate analysis restricted to the alloHCT group, short time since transplantation, low B-cell count, low intensity conditioning, GvHD, and immunosuppressive treatment at the vaccination were associated with lack of seroconversion. In the multivariate model, the only negative predictor of seroconversion remained treatment with calcineurin inhibitor (CNI). In conclusion, the BNT162b2 mRNA vaccine is highly immunogenic in patients after HCT, but treatment with CNI at the time of vaccination has a strong negative impact on the humoral response.

Outcome of SARS-CoV-2-Infected Polish Patients with Chronic Lymphocytic Leukemia.

BACKGROUND: The severe acute respiratory syndrome coronavirus (SARS-CoV-2) has become the cause of a worldwide pandemic, and its clinical infection course in patients with hematological malignancies may be severe. METHODS: We performed a retrospective study on 188 chronic lymphocytic leukemia patients (CLL) with COVID-19 infection. RESULTS: At the time of infection 51 patients (27.1%) were treated with Bruton tyrosine kinase inhibitor (BTKi), 46 (24.5%) with anti-CD20 antibodies while 37 patients (19.7%) received venetoclax. In total, 111 patients (59.0%) required hospitalization and 50 patients (26.5%) died due to COVID-19. Patients with poor performance status (ECOG >1; p = 0.02), advanced age (>65 years; p = 0.04), low hemoglobin concentration (≤10 g/dl; p = 0.0001), low platelets (<100 × 109/L; p = 0.003), and elevated lactate dehydrogenase level (LDH; p = 0.014) had an increased risk of death due to COVID-19. Neither CLL treatment status (treatment naïve vs. treated) nor the type of CLL-directed treatment had impact on the SARS-CoV-2 related risk of death. The multivariate survival analysis showed that advanced age (p = 0.009) and low platelet count (p = 0.0001) were associated with significantly shorter patients' overall survival. CONCLUSIONS: SARS-CoV-2 infection in CLL patients is associated with poor outcome regardless of administered CLL-directed treatment.

Long-term Efficacy of Ibrutinib in Relapsed or Refractory Chronic Lymphocytic Leukemia: Results of the Polish Adult Leukemia Study Group Observational Study.

BACKGROUND/AIM: To study the long-term clinical efficacy and tolerability of ibrutinib monotherapy in real-world relapsed and refractory chronic lymphocytic leukemia (RR-CLL) patients outside clinical trials. PATIENTS AND METHODS: Clinical data of 171 RR-CLL patients treated with ibrutinib were collected within the observational study of the Polish Adult Leukemia Study Group. RESULTS: Median patient age was 64 years. Patients were pretreated with 3 (1-10) median lines of therapy, while 42 (24.6%) had 17p deletion. The median observation time was 40 months (range=1-59 months), while median ibrutinib monotherapy reached 37.5 months (range=0.4-59.2 months). Response was noted in 132 (77.2%) patients. The estimated 5-year progression-free survival (PFS) and overall survival (OS) rates were 61.1% (95%CI=49.3-70.9%) and 56.8% (95%CI=45.6-66.6%), respectively. At the time of analysis 97 (56.7%) remained under ibrutinib monotherapy. CONCLUSION: Ibrutinib is clinically effective and tolerable as a monotherapy in real-world RR-CLL patients.

Ibrutinib discontinuation in patients with relapsed or refractory chronic lymphocytic leukemia treated in a compassionate use program: A report from the Polish Adult Leukemia Study Group (PALG).

BACKGROUND: Development of a novel class of drugs, the B-cell receptor-signaling inhibitors, including ibrutinib, has been a major achievement in the therapy of refractory or relapsed chronic lymphocytic leukemia (CLL). However, the CLL patients who have discontinued the ibrutinib treatment in clinical trials have been reported to have poor prognosis. OBJECTIVES: In this retrospective study by the Polish Adult Leukemia Group (PALG), we analyzed the reasons for ibrutinib cessation and outcomes after discontinuing ibrutinib in refractory or relapsed CLL patients treated in a compassionate use program in Poland. MATERIAL AND METHODS: Polish CLL patients were included if they discontinued ibrutinib for any reason. The clinical data on the course of ibrutinib treatment was collected anonymously using electronic Case Report Forms (CRFs). The causes of discontinuation of ibrutinib as reported by the treating physicians were analyzed. RESULTS: Thirty-seven patients who discontinued ibrutinib were identified. The median duration of ibrutinib treatment in this group was 4.4 months (range: 0.2-25.2). The main reason for discontinuing ibrutinib was adverse events (n = 20, 54%), while 14 (38%) patients discontinued therapy due to disease progression and 3 (8%) due to other causes. The most common treatment complications that led to ibrutinib cessation were severe respiratory tract infections (9 patients, 24%). In the group discontinuing ibrutinib for progressive disease, 11 patients progressed with untransformed CLL, while in 3 patients, a rare type of Richter transformation to Hodgkin's lymphoma was diagnosed. Twenty-nine patients (78%) died during the follow-up period, and median overall survival (OS) reached 2.0 months (95% CI = 0.8-5.5 months). Importantly, no significant survival difference was detected between patients who discontinued ibrutinib due to disease progression and due to adverse events. CONCLUSIONS: The results of this analysis indicate that ibrutinib discontinuation in relapsed or refractory CLL is associated with poor prognosis regardless of the reason for ibrutinib cessation.

Efficacy of daratumumab monotherapy in real-world heavily pretreated patients with relapsed or refractory multiple myeloma.

PURPOSE: Daratumumab is a promising new agent for relapsed/refractory multiple myeloma (RRMM). However, there are limited data on its clinical activity and tolerability in the real-world patients. The purpose of this study is to determine the efficacy and toxicity profile of daratumumab monotherapy in the real-life setting. PATIENTS AND METHODS: Thirty RRMM patients treated with daratumumab who had previously received at least three treatment lines including a proteasome inhibitor and an immunomodulatory drug or had been double refractory (DRMM) were included to the Polish Myeloma Group observational study. RESULTS: The objective response rate to daratumumab was 42.8%. Median progression-free survival (PFS) and overall survival reached 9.5 and 13.8 months, respectively. Importantly, patients with DR-MM had a significantly shorter PFS than other patients (median PFS of 4.1 vs. 12.1 months). Daratumumab was generally well tolerated, however two patients had their therapy interrupted due to adverse events. CONCLUSION: Daratumumab monotherapy has significant activity and good tolerance in heavily pretreated RRMM patients.