Imaging flow cytometry-based multiplex FISH for three IGH translocations in multiple myeloma.

Three types of chromosomal translocations, t(4;14)(p16;q32), t(14;16)(q32;q23), and t(11;14)(q13;q32), are associated with prognosis and the decision making of therapeutic strategy for multiple myeloma (MM). In this study, we developed a new diagnostic modality of the multiplex FISH in immunophenotyped cells in suspension (Immunophenotyped-Suspension-Multiplex (ISM)-FISH). For the ISM-FISH, we first subject cells in suspension to the immunostaining by anti-CD138 antibody and, then, to the hybridization with four different FISH probes for genes of IGH, FGFR3, MAF, and CCND1 tagged by different fluorescence in suspension. Then, cells are analyzed by the imaging flow cytometry MI-1000 combined with the FISH spot counting tool. By this system of the ISM-FISH, we can simultaneously examine the three chromosomal translocations, i.e, t(4;14), t(14;16), and t(11;14), in CD138-positive tumor cells in more than 2.5 × 104 nucleated cells with the sensitivity at least up to 1%, possibly up to 0.1%. The experiments on bone marrow nucleated cells (BMNCs) from 70 patients with MM or monoclonal gammopathy of undetermined significance demonstrated the promising qualitative diagnostic ability in detecting t(11;14), t(4;14), and t(14;16) of our ISM-FISH, which was more sensitive compared with standard double-color (DC) FISH examining 200 interphase cells with its best sensitivity up to 1.0%. Moreover, the ISM-FISH showed a positive concordance of 96.6% and negative concordance of 98.8% with standard DC-FISH examining 1000 interphase cells. In conclusion, the ISM-FISH is a rapid and reliable diagnostic tool for the simultaneous examination of three critically important IGH translocations, which may promote risk-adapted individualized therapy in MM.

Pretreatment serum level of interleukin-6 predicts carfilzomib-induced hypertension in relapsed/refractory multiple myeloma.

Carfilzomib (CFZ) constitutes powerful combinatory therapy for relapsed/refractory multiple myeloma (RRMM); however, cardiovascular adverse events (CVAEs) have been shown as major treatment obstacles with the use of CFZ. Along with our multi-institutional prospective observational study by the Kyoto Clinical Hematology Study Group on the efficacy and safety of CFZ-based treatments (UMIN000025108), we here performed an ad hoc analysis of CFZ-related CVAEs in 50 patients with RRMM. We analyzed the association between CFZ-related CVAEs and pre-planned examinations, including patients' background, electrocardiographic findings, echocardiographic findings, and serum/plasma levels of 18 potential candidate biomarkers. The common CVAEs were hypertension (42%), arrhythmia (14%), and prolongation of QT corrected interval (10%), whereas no serious CVAEs occurred. The pretreatment serum level of interleukin-6 was identified as a significant risk factor for CFZ-related hypertension. This study revealed hypertension as the most frequent CFZ-related CVAE and suggested that baseline serum interleukin-6 is a useful predictor for CFZ-induced hypertension.

Clinical impacts of frailty, poor performance status, and advanced age in carfilzomib-containing treatment for relapsed/refractory multiple myeloma: post hoc investigation of the KOTOSG multicenter pilot prospective observational study.

We conducted a post hoc analysis of our previous pilot observational study on the efficacy and safety of carfilzomib (CFZ)-containing therapy in 50 patients with relapsed/refractory multiple myeloma in routine practice to clarify the relationships between three major criteria for vulnerability (frailty, poor performance status [PS], and advanced age [≥ 75 years]) and their clinical impact on efficacy and adverse events (AEs). Sixteen patients fulfilled at least one and five patients fulfilled all three criteria. The overall response rate was not significantly affected by frailty, poor PS, and/or advanced age; however, frailty and advanced age were significantly associated with shorter progression-free survival (PFS). In contrast, no significant difference in PFS was observed between patients with PS0-1 or PS2-4. The three criteria for vulnerability were associated with more frequent hematologic AEs: frailty, poor PS, and/or advanced age significantly increased the risk of grade 3-4 anemia and lymphopenia. However, these criteria were not associated with increased risk of other non-hematologic AEs except infection. Collectively, these results demonstrate the need to carefully manage severe hematologic AEs in vulnerable patients and perform disease-specific assessment of frailty to predict prognosis.

Prognostic impact of resistance to bortezomib and/or lenalidomide in carfilzomib-based therapies for relapsed/refractory multiple myeloma: The Kyoto Clinical Hematology Study Group, multicenter, pilot, prospective, observational study in Asian patients.

BACKGROUND: Combinatory strategies with carfilzomib (CFZ), a second-generation proteasome inhibitor, plus dexamethasone (DEX) with or without lenalidomide (LEN) have shown promising efficacy for patients with relapsed/refractory multiple myeloma (RRMM) in pivotal clinical trials. However, their effects on patients who were resistance to bortezomib (BTZ) and/or LEN have not been fully evaluated in a daily practice setting. AIMS: To evaluate the real-world efficacy and safety of CFZ-based treatments; that is, CFZ with LEN plus DEX (KRD therapy) and CFZ with DEX (KD therapy), in Asian patients, we conducted a multicenter pilot prospective observational study in the Kyoto Clinical Hematology Study Group. METHODS AND RESULTS: All 50 patients with RRMM enrolled in this study were treated with CFZ-based treatments between 2017 and 2019. KRD and KD were administered to 31 and 19 patients, respectively. The overall response rates (ORRs) were 80.6% with KRD and 73.7% with KD. Two-year progression-free survival (PFS) and overall survival (OS) were 58.5% and 79.7% with KRD, and 23.1% and 52.6% with KD. By multivariate analysis, refractoriness to BTZ and to LEN were identified as independent unfavorable factors for both PFS and OS. The common non-hematologic AEs included hypertension (42.0%), fever (24.0%), fatigue (24.0%), and infection (16.0%). No serious heart failure was observed. This study is registered as UMIN000025108. CONCLUSION: This study suggests the need of the development of novel CFZ-containing strategy which can overcome the refractoriness to BTZ and/or LEN, while both KRD and KD were shown to be mostly feasible in Asian patients in a daily practice setting.

Low-dose dasatinib in older patients with chronic myeloid leukaemia in chronic phase (DAVLEC): a single-arm, multicentre, phase 2 trial.

BACKGROUND: BCR-ABL1 tyrosine kinase inhibitors (TKIs) are commonly initiated in older patients with chronic myeloid leukaemia in the chronic phase at standard doses. However, because of their safety profile in this population, appropriate therapy has not been established. We aimed to investigate whether a lower than standard dose of dasatinib was an appropriate therapy for older patients with chronic myeloid leukaemia in the chronic phase. METHODS: DAsatinib, Very Low-dose, for Elderly CML-CP patients (DAVLEC) was a multicentre, single-arm, phase 2 trial done in 25 Japanese hospitals. We enrolled patients older than 70 years with newly diagnosed chronic myeloid leukaemia in the chronic phase, ECOG performance status 0-2, and no previous treatment for CML other than hydroxyurea within 4 weeks. Second-generation TKI dasatinib was given orally at a starting dose of 20% of the standard dose (20 mg/day). If the treatment was assessed as optimal response at 3 months, 6 months, and 9 months and adverse events were grade 2 or better (according to the NCI Common Toxicity Criteria v 4.0), the same dose was continued. If response was suboptimal and adverse events were grade 2 or better, the dose was increased by 20 mg/day. Once a dose reduction had been made because of a grade 3 or worse adverse event, there were no further dose increases. Treatment was discontinued if assessed as failure (disease progression to the accelerated phase or acute phase). The primary endpoint was the achievement of major molecular response at 12 months, assessed using a per-protocol analysis. This trial is registered at with the UMIN clinical trial registry, UMIN000024548, and has completed its planned observation period. FINDINGS: Between Nov 1, 2016, and Oct 30, 2019, 52 patients received first-line dasatinib therapy at 20 mg/day. The median age at diagnosis was 77·5 years (73·5-83·0). 35 (67%) patients were male and 17 (33%) were female. 31 (60%) of 52 patients reached major molecular response at 12 months (one-sided 95% CI 48-71), with a median follow-up of 366 days (IQR 353-372). Grade 3-4 adverse events were reported in 12 (23%) patients. Neutropenia was the most frequent grade 3-4 adverse event, occurring in three (6%) patients. No treatment-related deaths were observed. INTERPRETATION: Low-dose dasatinib at 20mg/day is worthy of consideration as a starting dose for older patients with newly diagnosed chronic myeloid leukaemia in the chronic phase. However, this dose needs to be further studied in a larger cohort and with a more ethnically diverse population. FUNDING: Bristol-Myers Squibb.

Detection of novel and recurrent conjoined genes in non-Hodgkin B-cell lymphoma.

For this study, we investigated comprehensive expression of conjoined genes (CGs) in non-Hodgkin B-cell lymphoma (B-NHL) cell line KPUM-UH1 by using paired-end RNA sequencing. Furthermore, we analyzed the expression of these transcripts in an additional 21 cell lines, 37 primary samples of various malignancies and peripheral blood mononuclear cells of four normal individuals. Seventeen CGs were detected in KPUM-UH1: CTBS-GNG5, SRP9-EPHX1, RMND5A-ANAPC, OTX1-EHBP1, ATF2-CHN1, PRKAA1-TTC33, LARP1-MRPL22, LOC105379697-BAK1, TIAM2-SCAF8, SPAG1-VPS13B, WBP1L-CNNM2, NARS2-GAB2, CTSC-RAB38, VAMP1-CD27-AS1, LRRC37A2-NSF, UBA2-WTIP and ZNF600-ZNF611. To our knowledge, 10 of these genes have not been previously reported. The various characteristics of the CGs included in- and out-of-frame fusions, chimeras involving non-coding RNA and transcript variants. A finding of note was that LARP1-MRPL2 was characterized as in-frame fusion and was recurrently expressed in B-NHL samples. In this study, variety of CGs was expressed both in malignant and normal cells, some of which might be specific to lymphoma.

EWSR1 overexpression is a pro-oncogenic event in multiple myeloma.

Multiple myeloma (MM) is cytogenetically, genetically and molecularly heterogenous even among subclones in one patient, therefore, it is essential to identify both frequent and patient-specific drivers of molecular abnormality. Following previous molecular investigations, we in this study investigated the expression patterns and function of the Ewing sarcoma breakpoint region 1 (EWSR1) gene in MM. The EWSR1 transcriptional level in CD138-positive myeloma cells was higher in 36.4% of monoclonal gammopathy of undetermined significance, in 67.4% of MM patients compared with normal plasma cells, and significantly higher in ten human myeloma-derived cell lines (HMCLs) examined. EWSR1 gene knockdown caused growth inhibition with an increase of apoptotic cells in NCI-H929 and KMS-12-BM cells. Gene expression profiling using microarray analysis suggested EWSR1 gene knockdown caused transcriptional modulation of several genes associated with processes such as cell proliferation, cell motility, cell metabolism, and gene expression. Of particular, EWSR1 gene knockdown caused upregulation of let-7c and downregulation of its known targets K-RAS and AKT. Finally, our analysis using community database suggested that high EWSR1 expression positively associates with poor prognosis and advanced disease stage in MM. These findings suggest that EWSR1 overexpression is a pro-oncogenic molecular abnormality that may participate in MM progression.

Aberrant BUB1 Overexpression Promotes Mitotic Segregation Errors and Chromosomal Instability in Multiple Myeloma.

Chromosome instability (CIN), the hallmarks of cancer, reflects ongoing chromosomal changes caused by chromosome segregation errors and results in whole chromosomal or segmental aneuploidy. In multiple myeloma (MM), CIN contributes to the acquisition of tumor heterogeneity, and thereby, to disease progression, drug resistance, and eventual treatment failure; however, the underlying mechanism of CIN in MM remains unclear. Faithful chromosomal segregation is tightly regulated by a series of mitotic checkpoint proteins, such as budding uninhibited by benzimidazoles 1 (BUB1). In this study, we found that BUB1 was overexpressed in patient-derived myeloma cells, and BUB1 expression was significantly higher in patients in an advanced stage compared to those in an early stage. This suggested the involvement of aberrant BUB1 overexpression in disease progression. In human myeloma-derived cell lines (HMCLs), BUB1 knockdown reduced the frequency of chromosome segregation errors in mitotic cells. In line with this, partial knockdown of BUB1 showed reduced variations in chromosome number compared to parent cells in HMCLs. Finally, BUB1 overexpression was found to promote the clonogenic potency of HMCLs. Collectively, these results suggested that enhanced BUB1 expression caused an increase in mitotic segregation errors and the resultant emergence of subclones with altered chromosome numbers and, thus, was involved in CIN in MM.

Second primary malignancy after rituximab-containing immunochemotherapy for diffuse large B cell lymphoma.

Extended post-therapy long-term survival of patients with diffuse large B cell lymphoma (DLBCL) may also lead to an increase of late adverse events. We retrospectively investigated the frequency and clinical manifestation of second primary malignancy (SPM) after rituximab-containing immunochemotherapy in patients with DLBCL treated at seven institutes belonging to the Kyoto Clinical Hematology Study Group (KOTOSG) from the perspective of the existence of past or synchronous cancer history. In a median follow-up period of 899 days, 69 SPMs were observed in 58 of 809 patients. The most frequent SPM was gastric cancer, followed by lung cancer and colorectal cancer. The cumulative incidence of SPM increased steadily over time and was not significantly influenced by the presence or absence of past or synchronous cancer history. Our study suggests the need for careful attention to SPM in patients with DLBCL in daily practice.

Lenalidomide and pomalidomide potently interfere with induction of myeloid-derived suppressor cells in multiple myeloma.

An increase in immunosuppressive myeloid-derived suppressor cells (MDSCs) is associated with disease progression and treatment resistance in multiple myeloma (MM). We investigated the mechanisms underlying MDSC induction, and sought to discover a strategy for prevention of MDSC induction in MM. Using a transwell co-culture system, four of nine examined human myeloma-derived cell lines (HMCLs) were potent in inducing monocytic (M)-MDSCs from normal peripheral blood mononuclear cells (PBMCs). As the results, we identified that secretion of C-C motif chemokine ligand 5 (CCL5) and macrophage migration inhibitory factor (MIF) by myeloma cells is a prerequisite for induction of MDSCs in MM. The immunomodulatory drug (IMiD) compounds, such as lenalidomide (LEN) and pomalidomide (POM), were identified as potent inhibitors of MDSC induction through bidirectional molecular effects of cereblon (CRBN)-dependent and -independent downregulation of CCL5 and MIF in myeloma cells; and downregulation of C-C motif chemokine receptor 5, a receptor for CCL5, and induction of interferon regulatory factor 8, a critical transcription factor for monocytic differentiation, in PBMCs. In the present study of the molecular mechanisms underlying MDSC induction, we identified a novel effect of LEN and POM of inhibiting MDSC induction via overlapping regulatory effects in myeloma cells and normal PBMCs.

Serine-227 in the N-terminal kinase domain of RSK2 is a potential therapeutic target for mantle cell lymphoma.

RSK2 is a serine/threonine kinase downstream signaling mediator in the RAS/ERK signaling pathway and may be a therapeutic target in mantle cell lymphoma (MCL), an almost incurable disease subtype of non-Hodgkin lymphoma. In this study, serine-227 (RSK2Ser227 ) in the N-terminal kinase domain (NTKD) of RSK2 was found to be ubiquitously active in five MCL-derived cell lines and in tumor tissues derived from five MCL patients. BI-D1870, an inhibitor specific to RSK2-NTKD, caused RSK2Ser227 dephosphorylation, and thereby, induced dose-dependent growth inhibition via G2 /M cell cycle blockade and apoptosis in four of the five cell lines, while one cell line showed only modest sensitivity. In addition, RSK2 gene knockdown caused growth inhibition in the four BI-D1870-sensitive cell lines. Comparative gene expression profiling of the MCL-derived cell lines showed that inhibition of RSK2Ser227 by BI-D1870 caused downregulation of oncogenes, such as c-MYC and MYB; anti-apoptosis genes, such as BCL2 and BCL2L1; genes for B cell development, including IKZF1, IKZF3, and PAX5; and genes constituting the B cell receptor signaling pathway, such as CD19, CD79B, and BLNK. These findings show that targeting of RSK2Ser227 enables concomitant blockade of pathways that are critically important in B cell tumorigenesis. In addition, we found favorable combinatory growth inhibitory effects of BI-D1870 with inhibitors of BTK (ibrutinib), AKT (ipatasertib), and BCL2 (venetoclax) in cell characteristic-dependent manners. These results provide a rationale for RSK2Ser227 in the NTKD as a potential therapeutic target in MCL and for future development of a novel bioavailable RSK2 NTKD-specific inhibitor.

Tuberculosis Peritonitis During Treatment of Polycythemia Vera with Ruxolitinib.

Ruxolitinib is a selective JAK1/2 inhibitor that is widely used for the treatment of myeloproliferative neoplasms (MPNs), including myelofibrosis and polycythemia vera (PV). Despite its clinical efficacy for MPNs, ruxolitinib possesses immunosuppressive properties that potentially increase the risks for opportunistic infection, such as mycobacterium tuberculosis (MTB) infection, and reactivation of occult viral infection. Herein, we report the case of a 76-year-old male with PV who developed tuberculosis peritonitis under ruxolitinib therapy for 28 weeks. While previous studies and case reports have suggested an increased risk of MTB infection of various organs during ruxolitinib treatment of MPNs, this case is apparently the first of tuberculosis peritonitis in a patient with MPN treated with ruxolitinib. A review of previous case reports suggests the need for careful observation for MTB from the relatively early phase of ruxolitinib treatment, given that the median duration from the start of ruxolitinib treatment to the emergence of MTB was 20 weeks (range: 3-88 weeks). Clinicians should consider tuberculosis peritonitis as a differential diagnosis when patients with MPN treated with ruxolitinib develop infectious abdominal symptoms.

Tumor-specific transcript variants of cyclin D1 in mantle cell lymphoma and multiple myeloma with chromosome 11q13 abnormalities.

Cyclin D1 (CCND1) overexpression is an early and unifying oncogenic event in mantle cell lymphoma (MCL) and multiple myeloma (MM) with chromosome 11q13 abnormalities. Herein, we report newly discovered transcript variants of the CCND1 gene in MCL and MM cells with chromosome 11q13 abnormalities. These transcript variants, designated CCND1.tv., covered the full-length coding region of CCND1 with longer 5'-untranslated regions (5'-UTRs) of CCND1 and occasionally contained a novel exon. CCND1.tv. was specifically detectable in patient-derived primary MCL or MM cells with chromosomal translocation t(11;14)(q13;q32), but not in t(11;14)-negative cells. The lengths of the 5'-UTR sequences of CCND1.tv. differed among patients and cell lines. Introduction of CCND1.tv. led to increased expression of normal-sized CCND1 protein in HEK293 cells. Furthermore, mTOR inhibition by rapamycin or serum starvation reduced ectopic expression of CCND1.tv.-derived CCND1 protein, but not 5'-UTR less CCND1-derived CCND1 protein in HEK293 cells, suggesting that the protein expression of CCND1.tv. is regulated by the mTOR pathway. Our results suggest that the aberrant expression of CCND1.tv. may contribute to the understanding of the pathogenesis of MCL and MM with 11q13 abnormalities.

BRD4-Regulated Molecular Targets in Mantle Cell Lymphoma: Insights into Targeted Therapeutic Approach.

BACKGROUND: Since bromodomain-containing protein 4 (BRD4) facilitates the transcription of genes important for neoplastic cells in a cancer-type specific manner, BRD4-regulated molecules may also include therapeutic targets for mantle cell lymphoma (MCL), a treatment-refractory subtype of malignant lymphoma. MATERIALS AND METHODS: In order to uncover direct BRD4-regulated targets in MCL, we performed integrated analysis using the pathway database and the results of both gene-expression profiling and chromatin immunoprecipitation with parallel sequencing for BRD4. RESULTS: Treatment with BRD4 inhibitor I-BET151 exerted a dose-dependent inhibitory effect on cell proliferation in MCL cell lines. BRD4 was found to directly regulate series of genes involved in the B-cell receptor (BCR) signaling pathway, including B-cell linker (BLNK), paired box 5 (PAX5), and IKAROS family zinc finger 3 (IKZF3), and several oncogenes, such as MYB. Indeed, the combinatory inhibition of BCR pathway and IKZF showed an additive antitumor effect. CONCLUSION: Concomitant targeting multiple BRD4-regulated molecules may constitute a rational therapeutic strategy for MCL.

Sequential therapy of four cycles of bortezomib, melphalan, and prednisolone followed by continuous lenalidomide and dexamethasone for transplant-ineligible newly diagnosed multiple myeloma.

The combinations of melphalan, bortezomib, and prednisolone (VMP) and of lenalidomide and dexamethasone (Rd) are standard treatment strategies for transplant-ineligible newly diagnosed multiple myeloma (NDMM). To make the most of these two strategies, we investigated the efficacy and feasibility of first-line treatment with 4 cycles of VMP followed by continuous Rd therapy in a multi-institutional phase 2 study in Japanese patients with transplant-ineligible NDMM. Thirty-six patients of median age 74 years old with NDMM initially received 35-day cycles of VMP: oral melphalan (6 mg/m2) and prednisolone (60 mg/m2) on days 1 to 4 and bortezomib (1.3 mg/m2) on days 1, 8, 15, and 22. After 4 cycles of VMP, treatment was switched to 28-day cycles of Rd, which was continued until disease progression or emergence of an unacceptable adverse event (AE) in 33 patients, while one patient who achieved CR after VMP continued VMP at the physician's discretion. The overall response rates after VMP and after Rd were 66.7% and 86.1%, including CR rates of 5.6% and 36.1%, respectively. In a median follow-up period of 34.3 months, the progression-free survival and overall survival rates at 3 years were 43.2% and 81.3%, respectively. Grade 3-4 hematological AEs included neutropenia (39% with VMP and 24% with Rd) and thrombocytopenia (11% with VMP and 3% with Rd). There was no death due to an AE. In conclusion, sequential therapy with VMP followed by Rd is effective and mostly feasible for transplant-ineligible NDMM. The study is registered as UMIN000034815.

Recurrent intragenic exon rearrangements of SOBP and AUTS2 in non-Hodgkin B-cell lymphoma.

Expression of intragenic exon rearrangements (IERs) has reportedly been detected in both normal and cancer cells. However, there have been few reports of occurrence of these rearrangements specific to neoplasms including malignant lymphoma. In this study, we detected IERs of ten genes (NBPF8, SOBP, AUTS2, RAB21, SPATA13, ABCC4, WDR7, PHLPP1, NFATC1 and MAGED1) in non-Hodgkin B cell lymphoma (B-NHL) cell line KPUM-UH1 using a high-resolution single nucleotide polymorphism array and reverse transcription polymerase chain reaction using reversely directed divergent primers within exons involved in genomic intragenic gains followed by sequencing analysis. Among them, the IERs involved in SOBP (6q21) exon 2 and 3 and AUTS2 (7q11.22) exon 2-4 were the molecular lesions specific to tumors and were frequently detected in B-NHL samples. These IERs constitute novel genetic alterations of B-NHL, which might be associated with tumorigenesis and be useful as genetic biological markers.

Treatment rationale and design of a phase II study of narrow-band ultraviolet B phototherapy for cutaneous steroid-refractory acute graft-vs-host disease following allogenic stem-cell transplantation.

BACKGROUND: Acute graft-vs-host disease (aGVHD) is a common complication of allogenic hematopoietic stem-cell transplantation (allo-HSCT) and skin is the most common and often the 1st site at which aGVHD develops. Cutaneous aGVHD is usually treated with oral and/or topical corticosteroids as the 1st-line treatment; however, steroid-refractory aGVHD not only impairs patients' quality of life but also causes significant morbidity and mortality after allo-HSCT. Narrow-band ultraviolet B (NB-UVB) phototherapy has been utilized for a wide range of immunologic inflammatory skin diseases, but there is limited information on the efficacy, safety, and biomarkers for response prediction of NB-UVB for cutaneous aGVHD. AIMS: The purpose of this study is to investigate the efficacy and safety of NB-UVB phototherapy for steroid-refractory cutaneous aGVHD. PATIENTS AND METHODS: A total of 40 subjects aged from 16 to 70 years with steroid-refractory cutaneous aGVHD after allo-HSCT will be included in the trial. Patients with worse than stage 2 intestine/liver aGVHD will be excluded. Eligible patients will undergo NB-UVB phototherapy until resolution or further worsening of rash or occurrence of an unmanageable adverse event. The primary endpoint is the overall response rate. The secondary outcomes include rates for complete response, partial response, stable disease, progressive disease, duration of response, sparing effect on calcineurin inhibitors and/or corticosteroids, safety, and predictive biomarkers for treatment response. ETHICS AND DISSEMINATION: The protocol has been approved by the institutional Clinical Research Review Board of Kyoto Prefectural University of Medicine. Written informed consent will be obtained from all patients before registration, in accordance with the Declaration of Helsinki. Results of the study will be disseminated via publications in peer-reviewed journals. TRIAL REGISTRATION: Trial registration numbers UMIN000032426 and jRCTs052180005.

Prediction of delayed platelet engraftment after autologous stem cell transplantation for B-cell non-Hodgkin lymphoma.

Delayed platelet engraftment (DPE) is occasionally observed despite prompt neutrophil engraftment after autologous peripheral blood stem cell transplantation (auto-PBSCT). To identify risk factors for DPE and to develop a simple and clinically applicable system for predicting the time required for platelet recovery, we conducted a multi-institutional retrospective study in 144 patients with B-cell non-Hodgkin lymphoma who underwent auto-PBSCT. In a median observation period of 930 days (range: 25-5272 days), 139 patients successfully achieved platelet engraftment (≥50.0 × 109/L). The median duration for platelet engraftment was 19 days, and 130 patients had platelet engraftment within 40 days after auto-PBSCT; however, the other 14 patients failed to achieve platelet engraftment within 60 days. These 14 patients with DPE required a significantly greater number of apheresis procedures and had a lower pre-apheresis absolute lymphocyte count (PA-ALC) compared to those without DPE. Importantly, multivariate analysis revealed that the number of transplanted CD34+ cells (≤2.0 × 106/kg), number of required apheresis procedures (≥3 days), and PA-ALC (≤1.0 × 109/L) were independently associated with a longer time for platelet engraftment after auto-PBSCT. By incorporating these three independent factors as variables, we generated a new scoring system for prediction of the time and probability for platelet engraftment after auto-PBSCT.