Loss of or decrease in CD30 expression in four patients with anaplastic large cell lymphoma after brentuximab vedotin-containing therapy.

Brentuximab vedotin (BV), CD30 specific antibody drug conjugate, has been used to treat anaplastic large cell lymphoma (ALCL) and classic Hodgkin lymphoma (CHL); it is also used in the treatment of other CD30-positive peripheral T-cell lymphomas. We aimed to investigate the incidence and clinicopathological characteristics of patients with ALCL or CHL with loss of or decrease in CD30 expression after BV-containing therapy. Twelve and nine patients with refractory/relapsed CHL and ALCL, respectively, were analyzed after receiving BV-containing therapy. In four ALCL patients (44%), CD30 expression was lost/decreased in re-biopsy materials, including one with complete loss and three with a reduction of less than 20%. All 12 CHL patients showed consistent CD30 expression levels after BV treatment. Compared with five ALCL patients with consistent CD30 expression, four ALCL patients with a loss of/decrease in CD30 expression received a higher cumulative dose of BV (P = 0.014) and revealed a lower intensity of CD30 expression in initial biopsy materials (P = 0.017). The subtypes of ALCL (ALK positive, ALK negative, and primary cutaneous) were not related to the loss of/decrease in CD30 expression. In conclusion, 44% of ALCL patients, regardless of histological subtypes, showed a loss of/decrease in CD30 expression after receiving BV-containing therapy, but this phenomenon was not observed in CHL patients. A higher cumulative dose of BV and a lower amount of CD30 antigen in tumor cells in the initial biopsy materials might be predictors of a loss of/decrease in CD30 expression in ALCL patients.

Diffuse large B-cell lymphoma with composite germinal center and non-germinal center types: A report of two cases.

We report two cases of diffuse large B-cell lymphoma (DLBCL) with composite germinal center B-cell (GCB) and non-GCB types. Case 1 was a 72-year-old woman with inguinal lymph node swelling. Two morphologically different lesions were concurrently observed in needle biopsy specimens. One lesion was DLBCL with centroblastic morphology and a GCB phenotype (CD10+, BCL6+, and MUM1-), according to the Hans algorithm. The other lesion was DLBCL with anaplastic morphology and a non-GCB phenotype (CD10-, BCL6+, and MUM1+). Considering cellular atypia, the GCB-type DLBCL likely progressed to non-GCB-type DLBCL. Case 2 was a 34-year-old man who underwent ileocecal resection, with four lesions observed in the ileum. All four lesions indicated centroblastic morphology. Three lesions showed a GCB phenotype (CD10+, BCL6+, and MUM1+), while the other showed a non-GCB phenotype (CD10-, BCL6+, and MUM1+). These tumors were clonally related. BCL2 expression and MYC rearrangement were not related to changes in the cell of origin (COO) in either case. In conclusion, changes in the COO in DLBCL may not be uncommon. Therefore, investigation of the COO in other sites or at relapse may be needed if new drugs with different indications for each COO are developed.

Pathogenesis of Gastrointestinal Follicular Lymphomas: Consideration Based on Histopathology and Endoscopic Findings.

Gastrointestinal (GI) follicular lymphoma (FL) is the most frequently diagnosed extranodal FL; however, its pathogenesis is debatable. We investigated the distribution, endoscopic, and histopathologic findings of 366 GI FL samples obtained from 298 patients. FLs were most frequently observed in the small intestine (71%), including the duodenum (52%), but were also commonly found in the stomach (15%) and colon (12%). The proportion of granular lesions in the duodenum, terminal ileum, colon, and stomach was 74%, 39%, 24%, and 0%, respectively. Submucosal or ulcerated tumors were frequently observed in the stomach (48%) and colon (52%). Most GI FL showed grade 1 to 2 histology (89%) as well as CD10 + (93%) and BCL2 + (98%) positivity. There were no significant differences in the endoscopic or histologic findings between primary and secondary GI FLs. As known, the mucosa of the small intestine is thin and villous, while the mucosa of the stomach and colon is thicker and has a smooth surface. Granular lesions corresponding to very small FL were detected in the former but rarely in the latter. Nine (7%) patients with primary GI FL developed histologic transformation to diffuse large B-cell lymphoma (n=8) or high-grade B-cell lymphoma (n=1) 10 months to 14 years after the diagnosis of FL. Two patients died of lymphoma. In conclusion, the incidence and endoscopic findings differed, but the histopathology was similar in FLs in each site. These differences might be attributed to variations in each GI site's mucosal structure and the neoplastic follicles' size. Due to its characteristic structure, very small classic FLs might be detectable mainly in the small intestine.

Clinical utility of genomic profiling of AML using paraffin-embedded bone marrow clots: HM-SCREEN-Japan 01.

Next-generation sequencing of AML has identified specific genetic mutations in AML patients. Hematologic Malignancies (HM)-SCREEN-Japan 01 is a multicenter study to detect actionable mutations using paraffin-embedded bone marrow (BM) clot specimens rather than BM fluid in AML patients for whom standard treatment has not been established. The purpose of this study is to evaluate the presence of potentially therapeutic target gene mutations in patients with newly diagnosed unfit AML and relapsed/refractory AML (R/R-AML) using BM clot specimens. In this study, 188 patients were enrolled and targeted sequencing was undertaken on DNA from 437 genes and RNA from 265 genes. High-quality DNA and RNA were obtained using BM clot specimens, with genetic alterations successfully detected in 177 patients (97.3%), and fusion transcripts in 41 patients (23.2%). The median turnaround time was 13 days. In the detection of fusion genes, not only common fusion products such as RUNX1-RUX1T1 and KMT2A rearrangements, but also NUP98 rearrangements and rare fusion genes were observed. Among 177 patients (72 with unfit AML, 105 with R/R-AML), mutations in KIT and WT1 were independent factors for overall survival (hazard ratio = 12.6 and 8.88, respectively), and patients with high variant allele frequency (≥40%) of TP53 mutations had a poor prognosis. As for the detection of actionable mutations, 38% (n = 69) of patients had useful genetic mutation (FLT3-ITD/TKD, IDH1/2, and DNMT3AR822 ) for treatment selection. Comprehensive genomic profiling using paraffin-embedded BM clot specimens successfully identified leukemic-associated genes that can be used as therapeutic targets.

Romidepsin-induced durable remission for relapsed nodal peripheral T-cell lymphoma with T follicular helper phenotype after allogeneic hematopoietic cell transplantation.

Patients with recurrent peripheral T-cell lymphoma (PTCL) after allogeneic hematopoietic cell transplantation (HCT) have dismal outcomes. Nodal PTCL with the T follicular helper phenotype (PTCL-TFH) is uniquely sensitive to histone deacetylase inhibitors compared to non-TFH phenotypes. We report the case of a 19-year-old man who experienced recurrence of PTCL-TFH shortly after allogeneic HCT and subsequently achieved durable remission with romidepsin. Before HCT, the patient had refractory disease after CHOP and ESHAP chemotherapies but achieved a partial response after two cycles of romidepsin as salvage treatment. HLA-haploidentical peripheral blood stem cell transplantation was performed using conditioning with fludarabine 180 mg/sqm, melphalan 80 mg/sqm, and total body irradiation 2 Gy, and graft-versus-host disease (GVHD) prophylaxis with post-transplantation cyclophosphamide. One month after HCT, disease progression was observed in the lung. Romidepsin was readministered every 2 weeks at a reduced dose of 12 mg/sqm. After two cycles of romidepsin, the patient achieved a complete metabolic response without severe GVHD or other non-hematological toxicities. Romidepsin was discontinued after seven treatment cycles due to prolonged lymphopenia. The patient remains in complete remission 30 months after the last dose of romidepsin. Our experience suggests that romidepsin could be safely administered soon after allogeneic transplantation.

Diagnostic clues of BCL2-negative, faint, or controversial follicular lymphomas: a study of 103 cases.

BCL2 positivity by immunohistochemistry is helpful for the diagnosis of follicular lymphoma (FL); however, a minority of FL cases are BCL2-negative, and the diagnosis is thus challenging. We retrospectively analyzed the incidence, morphology, immunophenotype, and genetic status of BCL21+ (weakly/focally positive by clone 124), BCL20 (negative), and BCL2controversial FLs compared with BCL22+ (strongly positive) FLs to clarify diagnostic clues. In 1068 FL cases, 103 (10%) with BCL21+ (37 cases, 4%), BCL20 (61 cases, 6%), or BCL2controversial (5 cases, 0.5%) were included in the final analysis. BCL21+ and BCL20 FLs tended to have limited stage disease, nodal disease, and grades 3A/3B histology and showed a higher complete response rate than BCL22+ FLs. Among 103 BCL20, BCL21+, or BCL2controversial FL cases, 34 (33%) had a diffuse area composed of CD20-positive small-to medium-sized lymphoid cells, a feature of low-grade B-cell lymphoma. Interfollicular dense CD20-positive cells and interfollicular clusters of CD10-positive cells were observed in 59% and 37% of cases, respectively. In remaining 13/40 cases (33%), BCL2 was converted to BCL22+ by other clones E17/SP66. CD23 and MUM1 were positive in 10/40 (25%) and 1/40 (3%) cases, respectively. IGH/BCL2 fusion and clonality were detected in 6/37 (16%) and 31/34 (91%) cases, respectively. In conclusion, morphological examination of the distribution of CD20-and/or CD10-positive cells and the presence of diffuse area could be used to diagnose FL in most cases. The majority of the remaining FL cases could be diagnosed using other BCL2 clones and clonality analyses.

Long-term safety profile of tirabrutinib: final results of a Japanese Phase I study in patients with relapsed or refractory B-cell malignancies.

Tirabrutinib is a Bruton's tyrosine kinase inhibitor for treating B-cell malignancies. We report the final results of a Phase I study of tirabrutinib in 17 Japanese patients with B-cell malignancies. Patients were administered tirabrutinib at a dose of 160 mg, 320 mg, or 480 mg once daily, or 300 mg twice daily (N = 3, 3, 4, and 7, respectively). Three patients continued tirabrutinib until study completion (November 30, 2020). Adverse events (AEs) occurred in all 17 patients, with Grade 3-4 AEs in 8 (47.1%), serious AEs in 7 (41.2%), drug-related AEs in 16 (94.1%), and Grade 3-4 drug-related AEs in 6 (35.3%). Drug-related AEs reported in 3 or more patients were rash, vomiting, neutropenia, arthralgia, and malaise. One additional serious AE (benign neoplasm of the lung, unrelated to tirabrutinib) occurred after the previous data cutoff (January 4, 2018). Tirabrutinib administration and response assessment were continued for over 4 years in 4 patients. The overall response rate was 76.5% (13/17 patients). The median (range) time to response and duration of response were 0.9 (0.9-5.9) months and 2.59 (0.08-5.45) years, respectively. These findings demonstrate the long-term safety and efficacy of tirabrutinib in Japanese patients with B-cell malignancies.Clinical trial registration: JapicCTI-142682 ( http://www.clinicaltrials.jp/ ).

The role of surveillance computed tomography in patients with follicular lymphoma.

Introduction: Surveillance computed tomography (CT) is performed during the follow-up of patients with lymphoma who have completed initial therapy. However, studies on the clinical benefit of surveillance CT for patients with incurable subtypes, such as follicular lymphoma (FL), are limited. This study aimed to evaluate the value of surveillance CT for patients with FL after achieving the first complete response (CR) or CR unconfirmed in the rituximab era. Methods: We retrospectively reviewed the medical records of patients with FL who achieved CR with first-line treatment between 2000 and 2016 at our institution. In patients who experienced first relapse, we examined the patient's clinical characteristics at the time of relapse, subsequent therapies, and post-relapse survival, based on the method of relapse detection. Results: Of the 248 patients who achieved CR after initial therapy, 109 had a relapse, with a median follow-up of 11 years; 100 were enrolled into this study. Relapse was detected by surveillance CT in 61 patients (surveillance CT group) and by means other than surveillance CT, such as the presence of patient-reported symptoms, physical findings, and blood work-up abnormalities (non-surveillance CT group), in 39 patients. There was no significant difference in the patients' characteristics at the time of relapse between the two groups, except for a higher incidence of extranodal involvement in the non-surveillance CT group. The method of relapse detection did not affect therapeutic selection after relapse and post-relapse survival. In this study, 86.8% of the 38 patients who relapsed with only deep lesions, such as mesenteric or retroperitoneal lymph nodes, had surveillance CT-detected relapse. Conclusion: Surveillance CT did not show any clinical benefit for patients with FL in CR; however, it might lead to early detection of relapse in cases of deep lesions that cannot be identified without imaging.

Feasibility and clinical utility of comprehensive genomic profiling of hematological malignancies.

Identification of genetic alterations through next-generation sequencing (NGS) can guide treatment decision-making by providing information on diagnosis, therapy selection, and prognostic stratification in patients with hematological malignancies. Although the utility of NGS-based genomic profiling assays was investigated in hematological malignancies, no assays sufficiently cover driver mutations, including recently discovered ones, as well as fusions and/or pathogenic germline variants. To address these issues, here we have devised an integrated DNA/RNA profiling assay to detect various types of somatic alterations and germline variants at once. Particularly, our assay can successfully identify copy number alterations and structural variations, including immunoglobulin heavy chain translocations, IKZF1 intragenic deletions, and rare fusions. Using this assay, we conducted a prospective study to investigate the feasibility and clinical usefulness of comprehensive genomic profiling for 452 recurrently altered genes in hematological malignancies. In total, 176 patients (with 188 specimens) were analyzed, in which at least one alteration was detected in 171 (97%) patients, with a median number of total alterations of 7 (0-55). Among them, 145 (82%), 86 (49%), and 102 (58%) patients harbored at least one clinically relevant alteration for diagnosis, treatment, and prognosis, respectively. The proportion of patients with clinically relevant alterations was the highest in acute myeloid leukemia, whereas this assay was less informative in T/natural killer-cell lymphoma. These results suggest the clinical utility of NGS-based genomic profiling, particularly for their diagnosis and prognostic prediction, thereby highlighting the promise of precision medicine in hematological malignancies.

CD3-and CD20-negative extramedullary non-Hodgkin leukemia/lymphoma: a histopathological study of 118 cases.

Histopathological diagnoses are challenging for rare CD3-and CD20-negative extramedullary leukemias/lymphomas. We report 118 cases of CD3- CD20-extramedullary leukemias/lymphomas (2.4% of 4977 cases). CD45 was positive in 68% of cases. Forty-nine (41%) cases were anaplastic large cell lymphomas. Thirty-five (30%) cases were large B-cell lymphomas/plasmablastic lymphomas positive for at least one of the following markers: CD79a, PAX5, CD19, CD138, and MUM1. Nine (8%) cases were peripheral T/NK-cell lymphomas, where at least CD43, CD45RO, or cytotoxic molecules were positive; 4, 3, and 2 cases were extranodal NK/T-cell lymphoma, nasal type, peripheral T-cell lymphoma-not otherwise specified, and adult T-cell leukemia/lymphoma, respectively. The remaining 25 (21%) cases included 11, 8, and 6 cases of myeloid sarcoma, blastic plasmacytoid dendritic cell neoplasm, and B- or NK-cell lymphoblastic leukemia/lymphoma, respectively. For large B-cell lymphoma/plasmablastic lymphoma diagnosis, MUM1 (92%) was the most sensitive marker, followed by CD79a (63%), PAX5 (52%), CD138 (42%), and CD19 (36%). EBER 1 and HHV8 were positive in 32% and 0% of the cases. For peripheral T/NK-cell lymphomas other than ALCL, CD45RO and CD43 were positive in nine cases; however, cytotoxic molecules (TIA1, 86%; granzyme B, 71%) were the most sensitive markers. In conclusion, most cases of the 118 (2.4%) CD3- CD20- extramedullary leukemia/lymphoma were represented by anaplastic large cell lymphomas (41%). The second most frequent group of neoplasia, large B-cell lymphoma/plasmablastic lymphoma (30%), characterized a special diagnostic challenge when B-cell markers were not expressed, requiring immunohistochemistry for multiple B-cell markers and molecular analysis in some cases.

The outcome of watchful waiting in patients with previously treated follicular lymphoma.

Watchful waiting (WW) is one of the standard approaches for newly diagnosed follicular lymphoma (FL) patients with low-tumor burden. However, the impact of WW in FL patients at the first progression, remains unclear. We reviewed 206 FL patients who experienced the first progression after responding to the initial treatment at our institution between 1998 and 2017. Patients were classified into either the WW cohort (132 patients) or the immediate treatment cohort (74 patients). Overall, the median follow-up from the first progression was 79.8 months (range, 2.1-227.0 months). In the WW cohort, the estimated median time to next treatment (TNT) was 19.7 months (95% confidence interval [CI], 13.4-30.2), and 76.5% (95% CI, 68.0-84.1) of the patients subsequently underwent the second-line treatment at 5 years. There was a significant difference in the median time to treatment failure in the WW cohort (72.8 months; 95% CI, 64.6-94.0) compared to the immediate treatment cohort (23.3 months; 95% CI, 13.4-38.8) (HR, 2.13; 95% CI, 1.48-3.06), whereas overall survival and the cumulative incidence of histological transformation were not significantly different between two cohorts. In a multivariate analysis, rituximab refractory status, progression of disease within 24 months from the induction of first-line therapy, and a high Follicular Lymphoma International Prognostic Index score at diagnosis were significantly associated with shorter TNT. Interestingly, 15 patients (11%) of the WW cohort experienced spontaneous tumor regression during WW, and their TNT (median, 82.1 months, 95% CI, 11.7-NA) was longer than that of the remaining patients in the WW cohort (median, 16.5 months, 95% CI, 13.0-25.4), with a significant difference (p = 0.01). The results of the present study suggested that WW could be a safe and reasonable option even at the first progression for the selected FL patients, without a negative impact on clinical outcomes.

Diagnostic utility and prognostic significance of the Ki-67 labeling index in diffuse large B-cell lymphoma transformed from follicular lymphoma: a study of 76 patients.

The diagnosis of histological transformation of follicular lymphoma can be challenging and ambiguous. We investigated the distribution of the Ki-67 labeling index of histological transformation of follicular lymphoma and determined its cutoff value to predict poor outcomes. The diagnostic criteria for histological transformation were a diffuse pattern of proliferation and a proportion of large lymphoma cells ≥20%. Of the 1121 patients with follicular lymphoma, 171 (15%) showed histological transformation to diffuse large B-cell lymphoma. Of these, 76 patients, whose biopsies were obtained from the sites with the highest maximum standardized uptake values, according to the positron emission tomography findings, were included. The Ki-67 index ranged from 16.8% to 98.4% (median, 60.6%). In patients with histological transformation, the most significant differences were found in progression-free survival (p = 0.087, 58% vs. 87% at 2 years) and overall survival (p = 0.024, 53% vs. 85% at 5 years) when a 70% cutoff was used. Additionally, overall survival was significantly shorter in patients with histological transformation with maximum standardized uptake values of ≥20 (p < 0.0001) and absence of a follicular lymphoma component (p = 0.004). A Ki-67 index of ≥70% was a significant adverse factor for overall survival in patients with histological transformation of follicular lymphoma and may predict poor outcomes.

Outcomes of hematopoietic cell transplantation for transformed follicular lymphoma.

This study characterized the outcomes of patients who underwent hematopoietic cell transplantation (HCT) for transformed follicular lymphoma (tFL), and clarified the association of low-dose anti-thymocyte globulin use with outcomes after allogeneic HCT. The retrospective study cohort included 74 consecutive patients who underwent autologous (n = 23) or allogeneic (n = 51) HCT at our center from 2000 to 2017. Compared with the allogeneic HCT group, the autologous HCT group underwent fewer systemic regimens before HCT (median 2 vs. 5, p < 0.001) and were more likely to have chemosensitive disease at HCT (100% vs. 82%, p = 0.05), while age, sex and HCT-specific comorbidity index were similar between the two groups. With a median follow-up of 5.8 years among survivors, the 5-year probability of progression-free survival was 64% after autologous HCT and 55% after allogeneic HCT (p = 0.21). The 5-year cumulative incidence of non-relapse mortality was 0% after autologous HCT and 9.5% after allogeneic HCT (p = 0.062). The 5-year cumulative incidence of disease progression was similar between autologous and allogeneic HCT (36% vs. 36%, respectively, p = 0.88). In the allogeneic HCT group, the use of low-dose anti-thymocyte globulin was associated with a lower incidence of severe acute GVHD but not with an increased risk of mortality or disease progression. More than half of patients with early phase chemosensitive tFL and approximately half of those with advanced-phase tFL achieved long-term progression-free survival with autologous and allogeneic HCT, respectively. Disease progression was the major cause of treatment failure after both types of HCT. Further strategies are needed to reduce the risk of disease progression.

Clinicopathological analysis of primary refractory diffuse large B-cell lymphoma treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone chemoimmunotherapy.

BACKGROUND: Approximately 15% of patients with diffuse large B-cell lymphoma (DLBCL) experience refractory or early relapsed disease after initial rituximab-containing chemoimmunotherapy is regarded as a primary refractory disease. Although the standard treatment for relapsed DLBCL is high-dose chemotherapy and autologous stem cell transplantation (HDC-ASCT), the efficacy of this approach for primary refractory DLBCL is not well understood. We aimed to investigate the clinicopathological characteristics and outcomes of patients with primary refractory DLBCL. METHODS: Sixty-nine consecutive patients with primary refractory DLBCL who were treated at our institution were categorized as partial responders (partial response to rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisolone [R-CHOP] or relapse within 6 months of R-CHOP) (n = 41) or primary progressors (no response to R-CHOP) (n = 28). Survival curves were constructed using the Kaplan-Meier method and compared using the log-rank test. RESULTS: At initial diagnosis, 70% of patients had Ann Arbor stage III/IV disease, 56% had non-germinal center B-cell-like type DLBCL, and 42% had double-expressor lymphoma (MYC and BCL2 expression). The 3-year overall survival rate was significantly poorer in the primary progressors group than in the partial responders' group (15% vs. 48%, p < 0.001). Four of 17 patients treated with HDC-ASCT were primary progressors; only one patient survived without relapse. Although double-expressor lymphoma status did not significantly impact overall survival among all patients (p = 0.794), it was identified as an independent poor prognostic factor in HDC-ASCT-treated patients (p = 0.002). CONCLUSIONS: We identified a subgroup of patients with primary refractory DLBCL who may not benefit from current treatment strategies. Further treatment development is needed to improve the outcomes of these patients.

Use of Core-Needle Biopsy for the Diagnosis of Malignant Lymphomas in Clinical Practice.

INTRODUCTION: Excisional biopsy (EB) is considered the gold standard for lymphoma diagnosis. Although recent advances in interventional radiology enable sampling with core-needle biopsy (CNB), only few studies evaluated the utility of CNB compared to that of EB. METHODS: We analyzed patients with lymphoma who had a diagnostic biopsy at the National Cancer Center Hospital during 2002-2017. We investigated the clinical and pathological characteristics of CNB in 2017. RESULTS: The proportion of CNB utility in total biopsy procedures had increased from 11 to 48% during the 15 years. In 2017, CNB was opted more frequently than EB for a biopsy of superficial, abdominal, or anterior mediastinal lesions. Only one out of 72 patients who had CNB required re-biopsy with EB because of insufficiency. The incidence of complications was comparable between CNB and EB: 2 (4%) cases of minor bleeding with CNB and 1 (8%) case of minor bleeding with EB. The median time from the first visit to biopsy was significantly shorter with CNB (5.5 days) than with EB (15 days). CONCLUSION: There is an increasing trend in the utility of CNB. CNB is a less invasive method with shorter time to biopsy and can be considered an alternative to EB.

Usefulness of hematopoietic progenitor cell monitoring to predict autologous peripheral blood stem cell harvest timing: A single-center retrospective study.

INTRODUCTION: In autologous peripheral blood stem cell harvest (APBSCH), CD34-positive cells have been measured to assess the numbers of hematopoietic stem cells, but measurement requires specialized equipment. Recently, there was a report that peripheral blood hematopoietic progenitor cells (HPCs) are useful indicators of the presence of hematopoietic stem cells. We examined the usefulness of HPC monitoring to predict APBSCH timing. METHODS: We retrospectively analyzed the relationship between HPC and collected CD34-positive cells in 84 consecutive patients who underwent APBSCH. RESULTS: According to the receiver operating characteristics curve for the collection of ≥2 × 106 CD34-positive cells/kg, the HPC cut-off value on the day before collection was 21/µL, while that on the day of collection was 41/µL. No significant factors were found in the univariate analysis except for the HPC count on the day before collection (p < 0.001) and the day of collection (p < 0.001). According to the multivariate analysis, the HPC count on the day before collection (p < 0.001) and the day of collection (p < 0.001) were also factors that strongly influenced the quantity of CD34-positive cells collected. CONCLUSION: Our results suggest that the HPC count on not only the day of collection but also the day before collection is a good indicator for appropriate APBSCH timing.

Clinicopathological factors and tumor microenvironment markers predicting watch-and-wait discontinuation in 82 patients with follicular lymphoma.

OBJECTIVES: In this study, we aimed to determine the clinicopathological factors influencing the treatment-free period in patients with follicular lymphoma (FL) using a watch-and-wait (WW) strategy. METHODS: We retrospectively assessed histopathological parameters of 82 patients with FL. RESULTS: The median time from diagnosis to WW discontinuation was 62 months (range, 3-138), and median follow-up was 86 months (range, 3-183). Intermediate or high-risk Follicular Lymphoma International Prognostic Index score (P = .012), non-duodenal-type (P = .011), higher numbers of interfollicular CD4+ (P = .038) and intrafollicular FOXP3+ cells (P = .024) in the tumor microenvironment, and Ki-67 index ≥10% (P = .031) were significant adverse factors for WW discontinuation in univariate analyses. CONCLUSION: Patients with adverse factors for WW discontinuation should be carefully observed during follow-up.

CDKN1C-mediated growth inhibition by an EZH1/2 dual inhibitor overcomes resistance of mantle cell lymphoma to ibrutinib.

Mantle cell lymphoma (MCL) is a rare subtype of non-Hodgkin's lymphoma, which is characterized by overexpression of cyclin D1. Although novel drugs, such as ibrutinib, show promising clinical outcomes, relapsed MCL often acquires drug resistance. Therefore, alternative approaches for refractory and relapsed MCL are needed. Here, we examined whether a novel inhibitor of enhancer of zeste homologs 1 and 2 (EZH1/2), OR-S1 (a close analog of the clinical-stage compound valemetostat), had an antitumor effect on MCL cells. In an ibrutinib-resistant MCL patient-derived xenograft (PDX) mouse model, OR-S1 treatment by oral administration significantly inhibited MCL tumor growth, whereas ibrutinib did not. In vitro growth assays showed that compared with an established EZH2-specific inhibitor GSK126, OR-S1 had a marked antitumor effect on MCL cell lines. Furthermore, comprehensive gene expression analysis was performed using OR-S1-sensitive or insensitive MCL cell lines and showed that OR-S1 treatment modulated B-cell activation, differentiation, and cell cycle. In addition, we identified Cyclin Dependent Kinase Inhibitor 1C (CDKN1C, also known as p57, KIP2), which contributes to cell cycle arrest, as a direct target of EZH1/2 and showed that its expression influenced MCL cell proliferation. These results suggest that EZH1/2 may be a potential novel target for the treatment of aggressive ibrutinib-resistant MCL via CDKN1C-mediated cell cycle arrest.

CD5-negative blastoid variant mantle cell lymphoma: a diagnostic dilemma.

We encountered two cases of CD5- blastoid variant mantle cell lymphoma (MCL), prompting us to investigate the proportion of CD5 negativity in MCL and assess the diagnosis of aggressive MCL variants. Among 117 patients diagnosed with MCL, CD5 negativity was observed in 13% (13/104) of cases with classical MCL and 15% (2/13) of cases with blastoid/pleomorphic variant MCL. Of the aggressive MCL variant cases, tumor cells exhibited intermediate nuclear size and required differential diagnosis between blastoid variant and classical MCL in six patients, and classical MCL cells were found in the background of aggressive variant tumors or in other sites in six patients. Of 1534 patients with diffuse large B-cell lymphoma (DLBCL), CD5 positivity was observed in 8% (121/1534) of cases. Immunohistochemical staining for cyclin D1 performed for these cases revealed one cyclin D1-positive and IGH/CCND1 fusion-positive case (0.9%, 1/114), namely pleomorphic variant MCL. Of the remaining 1413 patients initially diagnosed with CD5- DLBCL, the diagnoses of two patients (0.1%) were amended to CD5- blastoid variant MCL in the relapse phase based on morphology, cyclin D1 immunostaining, and fluorescence in situ hybridization. The incidence of CD5 negativity was similar between classical MCL and two aggressive variants. Accurate diagnosis of MCL variants was enabled by identifying a classical MCL component and/or CD5 positivity; however, we misdiagnosed two cases of CD5- blastoid variant MCL. A small number of MCL variants may be included in CD5- DLBCL cases. The diagnosis of CD5- aggressive variant MCL remains challenging but crucial because of its therapeutic significance.