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Acute erythroid leukemia (AEL) is a unique subtype of acute myeloid leukemia characterized by prominent erythroid proliferation whose molecular basis is poorly understood. To elucidate the underlying mechanism of erythroid proliferation, we analyzed 121 AEL using whole-genome, whole-exome, and/or targeted-capture sequencing, together with transcriptome analysis of 21 AEL samples. Combining publicly available sequencing data, we found a high frequency of gains and amplifications involving EPOR/JAK2 in TP53-mutated cases, particularly those having >80% erythroblasts designated as pure erythroid leukemia (10/13). These cases were frequently accompanied by gains and amplifications of ERG/ETS2 and associated with a very poor prognosis, even compared with other TP53-mutated AEL. In addition to activation of the STAT5 pathway, a common feature across all AEL cases, these AEL cases exhibited enhanced cell proliferation and heme metabolism and often showed high sensitivity to ruxolitinib in vitro and in xenograft models, highlighting a potential role of JAK2 inhibition in therapeutics of AEL.Significance:This study reveals the major role of gains, amplifications, and mutations of EPOR and JAK2 in the pathogenesis of pure erythroleukemia. Their frequent response to ruxolitinib in patient-derived xenograft and cell culture models highlights a possible therapeutic role of JAK2 inhibition for erythroleukemia with EPOR/JAK2-involving lesions.This article is highlighted in the In This Issue feature, p. 369

Supplementary Figure from Amplified EPOR/JAK2 Genes Define a Unique Subtype of Acute Erythroid Leukemia

Supplementary Table from Amplified EPOR/JAK2 Genes Define a Unique Subtype of Acute Erythroid Leukemia

Purpose: The Hedgehog signaling pathway is a key regulator of cell growth and differentiation during development. Whereas the Hedgehog pathway is inactive in most normal adult tissues, Hedgehog pathway reactivation has been implicated in the pathogenesis of several neoplasms including BCR-ABL1–positive leukemia. The clear link between the Hedgehog pathway and BCR-ABL1–positive leukemia led to an effort to identify small molecules to block the pathway.Experimental Design: We investigated the combined effects of vismodegib and ponatinib, a pan-ABL1 kinase inhibitor, in nonobese diabetic/severe-combined immunodeficiency (NOD/SCID) repopulating T315I BCR-ABL1–positive cells in vitro and in vivo.Results: We observed that combination with vismodegib and ponatinib helps to eliminate therapy-resistant NOD/SCID repopulating T315I BCR-ABL1–positive cells. The percentage of CD19-positive leukemia cells in peripheral blood was significantly lower in vismodegib + ponatinib–treated mice than that of the vehicle or ponatinib alone (P < 0.001). Spleen weights were also lower in vismodegib + ponatinib–treated mice than in ponatinib alone (P < 0.05). Overall tumor burden, as assessed by BCR-ABL mRNA from bone marrow cells, was significantly lower in vismodegib + ponatinib–treated mice than in ponatinib alone (P < 0.005). We also found that vismodegib significantly reduced BCR-ABL1–positive leukemia cell self-renewal in vitro as well as during serial transplantation in vivo.Conclusions: The combination with a Smo inhibitor and ABL1 tyrosine kinase inhibitors may help eliminate therapy-resistant T315I BCR-ABL1–positive leukemia cells. Our preclinical results indicate that vismodegib has potential as an important option for controlling minimal residual cells in BCR-ABL1–positive leukemia. Clin Cancer Res; 19(6); 1422–32. ©2012 AACR.

GO analysis of RUNX3-Tet2 KO MDS

RUNX3, a RUNX family transcription factor, regulates normal hematopoiesis and functions as a tumor suppressor in various tumors in humans and mice. However, emerging studies have documented increased expression of RUNX3 in hematopoietic stem/progenitor cells (HSPC) of a subset of patients with myelodysplastic syndrome (MDS) showing a worse outcome, suggesting an oncogenic function for RUNX3 in the pathogenesis of hematologic malignancies. To elucidate the oncogenic function of RUNX3 in the pathogenesis of MDS in vivo, we generated a RUNX3-expressing, Tet2-deficient mouse model with the pancytopenia and dysplastic blood cells characteristic of MDS in patients. RUNX3-expressing cells markedly suppressed the expression levels of Runx1, a critical regulator of hemaotpoiesis in normal and malignant cells, as well as its target genes, which included crucial tumor suppressors such as Cebpa and Csf1r. RUNX3 bound these genes and remodeled their Runx1-binding regions in Tet2-deficient cells. Overexpression of RUNX3 inhibited the transcriptional function of Runx1 and compromised hematopoiesis to facilitate the development of MDS in the absence of Tet2, indicating that RUNX3 is an oncogene. Furthermore, overexpression of RUNX3 activated the transcription of Myc target genes and rendered cells sensitive to inhibition of Myc-Max heterodimerization. Collectively, these results reveal the mechanism by which RUNX3 overexpression exerts oncogenic effects on the cellular function of and transcriptional program in Tet2-deficient stem cells to drive the transformation of MDS.Significance:This study defines the oncogenic effects of transcription factor RUNX3 in driving the transformation of myelodysplastic syndrome, highlighting RUNX3 as a potential target for therapeutic intervention.

Runx1 target genes

RUNX3 IHC and clinical data of MDS patients

PDF file - 47 KB, SK-9 cells were treated with 1 mM of nilotinib or 200 nM of dasatinib or 40 nM of ponatinib for 48 hrs. The cytoplasmic cell lysates and nuclear extracts were immunoblotted with anti-Gli1 Abs or anti-ABL Ab.

Primers for q-RT-PCR

Up- and down-regulated genes

CCR Translation for This Article from Combination of Ponatinib with Hedgehog Antagonist Vismodegib for Therapy-Resistant BCR-ABL1–Positive Leukemia

Motif enrichment analysis

Azacitidine is a mainstay of therapy for MDS-related diseases. The purpose of our study is to elucidate the effect of gene mutations on hematological response and overall survival (OS), particularly focusing on their post-treatment clone size. We enrolled a total of 449 patients with MDS or related myeloid neoplasms. They were analyzed for gene mutations in pre- (n=449) and post- (n=289) treatment bone marrow samples using targeted-capture sequencing to assess the impact of gene mutations and their post-treatment clone size on treatment outcomes. In Cox proportional hazard modeling, multi-hit TP53 mutation (HR, 2.03; 95% CI, 1.42-2.91; P

Germ line DDX41 variants have been implicated in late-onset myeloid neoplasms (MNs). Despite an increasing number of publications, many important features of DDX41-mutated MNs remain to be elucidated. Here we performed a comprehensive characterization of DDX41-mutated MNs, enrolling a total of 346 patients with DDX41 pathogenic/likely-pathogenic (P/LP) germ line variants and/or somatic mutations from 9082 MN patients, together with 525 first-degree relatives of DDX41-mutated and wild-type (WT) patients. P/LP DDX41 germ line variants explained ∼80% of known germ line predisposition to MNs in adults. These risk variants were 10-fold more enriched in Japanese MN cases (n = 4461) compared with the general population of Japan (n = 20 238). This enrichment of DDX41 risk alleles was much more prominent in male than female (20.7 vs 5.0). P/LP DDX41 variants conferred a large risk of developing MNs, which was negligible until 40 years of age but rapidly increased to 49% by 90 years of age. Patients with myelodysplastic syndromes (MDS) along with a DDX41-mutation rapidly progressed to acute myeloid leukemia (AML), which was however, confined to those having truncating variants. Comutation patterns at diagnosis and at progression to AML were substantially different between DDX41-mutated and WT cases, in which none of the comutations affected clinical outcomes. Even TP53 mutations made no exceptions and their dismal effect, including multihit allelic status, on survival was almost completely mitigated by the presence of DDX41 mutations. Finally, outcomes were not affected by the conventional risk stratifications including the revised/molecular International Prognostic Scoring System. Our findings establish that MDS with DDX41-mutation defines a unique subtype of MNs that is distinct from other MNs.

Despite a detailed understanding of the genes mutated in myelodysplastic syndromes (MDS), diagnostic and treatment decisions for patients with MDS rely primarily on clinical and cytogenetic variables as considered by the Revised International Prognostic Scoring System (IPSS-R). Here we describe the recently developed Molecular IPSS (IPSS-M), a clinico-genomic risk stratification system that considers clinical, cytogenetic and genetic parameters; the implementation of a web portal to facilitate its adoption, a strategy to handle missing variables, and the worldwide utilization of the web calculator as a clinical support tool. The IPSS-M was trained on 2,957 clinically annotated diagnostic MDS samples profiled for mutations in 156 driver genes. To maximize the clinical applicability of the IPSS-M and account for missing genetic data (i.e genes missing from a sequencing panel), we implemented a strategy to calculate a risk score under three scenarios: best, worst and average. Last, we developed an online calculator as a standalone single-page web application using VueJs, and D3Js for the interactive visualizations, deployed through a CI/CD pipeline on AWS, where collection of anonymous usage analytics allows to track adoption and usability of the new proposed model. The model incorporates clinical, morphological, genetic variables informed by cytogenetics and constructed from the presence of oncogenic mutations in 31 genes. It delivers a unique risk score for each individual patient, as well as an assignment to one of six IPSS-M risk strata. Compared to the IPSS-R the IPSS-M re-stratified 46% of MDS patients. The model was validated in an external dataset of 754 MDS patients. We released an open-access IPSS-M web calculator available at https://mds-risk-model.com. By specifying the patient clinical and molecular profiles, the tool returns the patient-specific IPSS-M risk score and category, and the probability estimates over time for three clinical endpoints, i.e. leukemia free survival (LFS), overall survival, and incidence of leukemic transformation. Since its launch in June 2022, the calculator has been used by >6000 users in >75 countries, reaching a daily average of 100 users per day. Risks have been calculated for >45,000 patient profiles. 99.28% of the sessions initiated reach an IPSS-M score, suggesting that the calculator is intuitive and easy to use. We trained and validated the IPSS-M on 3,711 patients, a patient tailored risk stratification tool for patients with MDS that considers clinical, morphological and genetic variables inclusive of cytogenetics and mutations in one of 31 genes. The development of a web based tool was instrumental to the global dissemination of the model, enabling non-expert users to leverage the power of molecular biomarkers in risk stratification for patients with MDS. Citation Format: Elsa Bernard, Juan E. Arango Ossa, Heinz Tuechler, Peter L. Greenberg, Robert P. Hasserjian, Yasuhito Nannya, Sean M. Devlin, Maria Creignou, Philippe Pinel, Lily Monier, Juan S. Medina-Martinez, Dylan Domenico, Martin Jädersten, Ulrich Germing, Guillermo Sanz, Arjan A. van de Loosdrecht, Olivier Kosmider, Matilde Y. Follo, Felicitas Thol, Lurdes Zamora, Ronald F. Pinheiro, Andrea Pellagatti, Detlef Haase, Pierre Fenaux, Monika Belickova, Michael R. Savona, Virginia M. Klimek, Fabio P. Santos, Jacqueline Boultwood, Ioannis Kotsianidis, Valeria Santini, Francesc Solé, Uwe Platzbecker, Michael Heuser, Peter Valent, Kazuma Ohyashiki, Carlo Finelli, Maria Teresa Voso, Lee-Yung Shih, Michaela Fontenay, Joop H. Jansen, José Cervera, Norbert Gattermann, Benjamin L. Ebert, Rafael Bejar, Luca Malcovati, Mario Cazzola, Seishi Ogawa, Eva Hellström-Lindberg, Elli Papaemmanuil. Implementation and adoption of a web tool to support precision diagnostic and treatment decisions for patient with myelodysplastic syndromes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6168.

The optimal combined chemotherapy regimen with rituximab has yet to be established for elderly patients with advanced-stage indolent B-cell lymphoma (B-NHL). A multicenter study was performed to evaluate the efficacy and toxicity of R-THP-COP therapy in elderly patients (aged 70–79 years) with newly diagnosed advanced-stage indolent B-NHL using the complete response rate (%CR) as the primary endpoint. Patients with newly diagnosed, clinical stage III/IV, indolent B-NHL, aged 70–79 years, with a performance status of 0–2 were eligible for this study. R-THP-COP consists of 375 mg/m2 of rituximab, 50 mg/m2 of pirarubicin, 750 mg/m2 of cyclophosphamide, 1.4 mg/m2 of vincristine, and 100 mg/day of oral prednisolone for 5 days. This study was discontinued due to poor accrual after the enrollment of 18 patients, although the planned sample size was 40 patients. The numbers of patients with follicular lymphoma, mucosa-associated lymphoid tissue lymphoma, and mantle cell lymphoma were 16, 1, and 1, respectively. The median age was 73 (range, 70 to 79) years. The %CR including unconfirmed CR was 45% (95% confidence interval: 25-66%) and the overall response rate was 72%. The estimated 5-year overall survival and progression-free survival rates were 55% and 28%, respectively. The major toxicity observed was grade 4 neutropenia (94%). Grade 4 non-hematological toxicities were not observed and no patients developed grade 3/4 cardiac toxicities. This phase II study provides useful information regarding the efficacy and toxicity of R-THP-COP therapy for patients aged 70 years or older with newly diagnosed, advanced-stage, indolent B-NHL, although the sample size was small.

Bone marrow mesenchymal stromal cells (BM-MSCs) from healthy donors are a promising source of cell therapy. However, their effectiveness in cancer remains less known. This study is the first to evaluate the quality of BM-MSCs obtained from young and elderly healthy volunteers (KNT cells). The KNT cells had normal karyotypes and were positive for MSC markers (CD90, CD73, CD105). When cultured under appropriate conditions, they showed adipogenic or osteogenic potential. Hence, the anti-neoplastic effects of secretory factors [supernatant or extracellular vesicles (EV)] from KNT cells were verified using several neoplastic cells (three multiple myeloma, three myeloid leukemia, and three lymphoma cell lines). The conditioned medium (CM), but not EV, of KNT cells derived from young healthy donors significantly inhibited myeloma and lymphoma cell proliferation, but enhanced myeloid leukemia proliferation. Anti-angiogenesis effect of CM and EV derived from young KNT against hematologic neoplasia-induced angiogenesis was evident and more prominent in CM than in EV but not evident in elderly KNT-derived EV. These findings indicate that the anti-tumor effect of KNT cells depends on the types of hematologic neoplasia, with elements existing in the supernatant and not in EVs. Therefore, BM-MSC may produce soluble factors that affect cell proliferation of neoplasia, causing cell-to-cell communication. The anti-angiogenesis effect of KNT cells depends on the age of BM-MSC donors.

Sphingosine 1-phosphate (S1P) is a bioactive lipid involved in cancer progression through its binding to S1P receptors (S1PRs). However, the association between multiple myeloma (MM) and S1P is unclear. The current study aimed to investigate the potential anti-cancer effects of fingolimod and sphingosine kinase (SK) inhibitors in myeloma cells and the effects of S1P-induced chemoresistance and neovascularization on MM cell proliferation. MM cell lines were treated with the S1PR1 antagonist fingolimod and the SK inhibitors ABC294640 and SK1-I, after which cell proliferation was measured. Protein expression was also assessed under each condition using immunoblotting. Serum S1P levels in patients with MM, monoclonal gammopathy of undetermined significance and healthy volunteers were assessed. Human umbilical vessel cells (HUVECs) were co-cultured with anti-S1P agents to assess the effect on cell migration. All treatments suppressed myeloma cell proliferation and caspase-3-mediated apoptosis by suppressing S1P activity. These findings suggest that S1P activation is associated with proliferation and survival for MM cells. S1P attenuated the proteosome inhibitor (PI) effect, while the anti-S1P agents recovered the effect. In addition, S1P promoted the migration and proliferation of HUVECs, whereas the S1P inhibitors reduced the influence of S1P. This study highlights the therapeutic potential of anti-S1P agents for MM treatment. Inhibition of S1P function may overcome resistance to PI developed by myeloma cells and inhibit the changes to the bone marrow microenvironment via neovascularization.

Acute erythroid leukemia (AEL) is a unique subtype of acute myeloid leukemia characterized by prominent erythroid proliferation whose molecular basis is poorly understood. To elucidate the underlying mechanism of erythroid proliferation, we analyzed 121 AEL using whole-genome/exome and/or targeted-capture sequencing, together with transcriptome analysis of 21 AEL samples. Combining publicly available sequencing data, we found a high frequency of gains/amplifications involving EPOR/JAK2 in TP53-mutated cases, particularly those having >80% erythroblasts designated as pure erythroid leukemia (10/13). These cases were frequently accompanied by gains/amplifications of ERG/ETS2 and associated with a very poor prognosis, even compared with other TP53-mutated AEL. In addition to activation of the STAT5 pathway, a common feature across all AEL cases, these AEL cases exhibited enhanced cell proliferation and heme metabolism and often showed high sensitivity to ruxolitinib in vitro and in xenograft models, highlighting a potential role of JAK2 inhibition in therapeutics of AEL., ゲノム解析から急性赤白血病の変異プロファイルと治療標的を解明 --特定の遺伝子変異群の組み合わせと、特徴となる遺伝子の増幅が鍵--. 京都大学プレスリリース. 2022-08-05.

Bone marrow stromal cells (BMSCs) interact with multiple myeloma (MM) cells in the bone marrow and create a permissive microenvironment for MM cell proliferation and survival. In this study, we investigated the role of extracellular vesicles (EVs) from BMSCs derived from patients with MM (MM-BMSCs). EV-encapsulated miR-10a expression was high while intracellular miR-10a was low in MM-BMSCs. We therefore hypothesized that miR-10a was packaged into EVs that were actively released into the extracellular space. Inhibition of EV release resulted in accumulation of intracellular miR-10a, inhibition of cell proliferation, and induction of apoptosis in MM-BMSCs. In contrast, proliferation and apoptosis of BMSCs derived from healthy individuals were unaffected by inhibition of EV release. Furthermore, miR-10a derived from MM-BMSCs was transferred into MM cells via EVs and enhanced their proliferation. These results suggest that inhibition of EV release induced apoptosis in MM-BMSCs and inhibited MM cell proliferation, indicating a possible role for MM-BMSC–targeted therapy.

Purpose: Monitoring response and resistance to 5-azacitidine (AZA) is essential when treating patients with myelodysplastic syndrome (MDS). To quantify methylated DNA not only in the promoter region but also in the gene body, we established a single-molecule methylation assay (SMMA). Patients and methods: We first investigated the methylation extent (expressed as methylation index [MI]) by SMMA among 28 MDS and 6 post-MDS acute myeloid leukemia patients. We then analyzed the MI in 13 AZA-treated patients. Results: Whole-blood DNA from all 34 patients had low MI values compared with healthy volunteers (P

Azacitidine is a mainstay of therapy for high-risk MDS and other myeloid neoplasms. A significant correlation between azacitidine response and clinical outcome suggests a potential role of mutational profiling based on next-generation sequencing (NGS) before and after therapy in evaluating response and predicting overall survival (OS), which however has not fully elucidated. Here through NGS-based mutational profiling of large cohorts (n=451) of azacitidine-treated patients with high-risk MDS and other myeloid neoplasms, we show significant roles of multi-hit TP53 and germline DDX41 mutations in pre-treatment samples and post-treatment clone size in the evaluation/prediction of azacitidine response and OS after azacitidine therapy, which outperformed the prediction based only on clinical response and IPSS-R score. Post-treatment clone size strongly correlated with clinical response with exception of large persistent mutations frequently affecting TET2 after achieving complete remission and those with DDX41 mutations, which poorly correlated with clinical response. Our results highlight the importance of evaluating mutations in both pre- and post-treatment samples in the assessment of response and the prediction of OS after azacitidine therapy.

Blast crisis (BC) predicts dismal outcomes in patients with chronic myeloid leukaemia (CML). Although additional genetic alterations play a central role in BC, the landscape and prognostic impact of these alterations remain elusive. Here, we comprehensively investigate genetic abnormalities in 136 BC and 148 chronic phase (CP) samples obtained from 216 CML patients using exome and targeted sequencing. One or more genetic abnormalities are found in 126 (92.6%) out of the 136 BC patients, including the RUNX1-ETS2 fusion and NBEAL2 mutations. The number of genetic alterations increase during the transition from CP to BC, which is markedly suppressed by tyrosine kinase inhibitors (TKIs). The lineage of the BC and prior use of TKIs correlate with distinct molecular profiles. Notably, genetic alterations, rather than clinical variables, contribute to a better prediction of BC prognosis. In conclusion, genetic abnormalities can help predict clinical outcomes and can guide clinical decisions in CML., In chronic myeloid leukaemia (CML), the drivers of blast crisis and resistance to tyrosine kinase inhibitors are not fully characterised. Here, the authors analyse a cohort of CML samples with genomic technologies and find that at least one driver alteration is associated with progression and worse prognosis.

To evaluate the mechanism underlying the communication between myeloid malignant and bone marrow (BM) microenvironment cells in disease progression, the current study established BM mesenchymal stromal cells (MSCs) and assessed extracellular vesicle (EV) microRNA (miR) expression in 22 patients with myelodysplastic syndrome (MDS) and 7 patients with acute myeloid leukemia and myelodysplasia-related changes (AML/MRC). Patients with MDS were separated into two categories based on the revised International Prognostic Scoring System (IPSS-R), and EV-miR expression in BM-MSCs was evaluated using a TaqMan low-density array. The selected miRs were evaluated using reverse transcription-quantitative PCR. The current study demonstrated that the expression of BM-MSC-derived EV-miR was heterogenous and based on MDS severity, the expression of EV-miR-101 was lower in high-risk group and patients with AML/MRC compared with the control and low-risk groups. This reversibly correlated with BM blast percentage, with which the cellular miR-101 from BM-MSCs or serum EV-miR-101 expression exhibited no association. Database analyses indicated that miR-101 negatively regulated cell proliferation and epigenetic gene expression. The downregulation of BM-MSC-derived EV-miR-101 may be associated with cell-to-cell communication and may accelerate the malignant process in MDS cells.

Multiple myeloma (MM) is a uniformly fatal disorder of B cells characterized by the accumulation of abnormal plasma cells. Phosphoinositide 3-kinase (PI3K) signaling pathways play a critical regulatory role in MM pathology. Copanlisib, also known as BAY80-6946, is a potent PI3Kα and δ inhibitor. In this study, we investigated the efficacy of copanlisib and a proteasome inhibitor using MM cell lines and primary samples. The p110α and δ catalytic subunits of the class PI3K increased, and carfilzomib activity reduced in the presence of a supernatant from the feeder cell line, HS-5. Phosphorylation of Akt and activation of caspase 3 and poly (ADP-ribose) polymerase (PARP) partially reduced upon carfilzomib treatment in the presence of HS-5. Apoptosis also decreased. Copanlisib treatment for 72 h inhibited growth in MM cell lines and induced apoptosis. Combination treatment of MM cells with carfilzomib and copanlisib caused greater cytotoxicity than that caused by either drug alone and increased apoptosis. Caspase 3 activity increased while that of Akt decreased after combination treatment with copanlisib and carfilzomib. Further, copanlisib inhibited vascular endothelial growth factor (VEGF)-mediated angiogenesis in vitro and in vivo. It also inhibited C-X-C motif chemokine 12 (CXCL12)-mediated chemotaxis. The data suggest that administration of the PI3K inhibitor, copanlisib, may be a powerful strategy against stroma-associated drug resistance of MM cells and can enhance the cytotoxic effects of proteasome inhibitors in such residual MM cells.

Summary Background Standard treatment for untreated advanced-stage follicular lymphoma is rituximab plus chemotherapy. The incidence of histological transformation of follicular lymphoma has been reported only in heterogeneously treated populations and rarely with long-term follow-up. Additionally, the incidence of secondary malignancies after treatment, without high-dose therapy for follicular lymphoma, is largely unknown. The aim of our study was to assess progression-free survival, overall survival, incidence of secondary malignancies, and incidence of histological transformation in a 10-year follow-up analysis of the JCOG0203 trial. Methods In the phase 2–3 randomised JCOG0203 trial, previously untreated patients with stage III or IV indolent B-cell lymphoma, including grades 1–3 follicular lymphoma, from 44 hospital centres in Japan, were randomly assigned (1:1) by use of a minimisation method to receive six cycles of R-CHOP (rituximab [375 mg/m2], given on day 1, plus cyclophosphamide [750 mg/m2], doxorubicin [50 mg/m2], vincristine [1·4 mg/m2, capped at 2·0 mg] given intravenously on day 3, and oral prednisone [100 mg once daily on days 3–7]) every 3 weeks (R-CHOP-21) or every 2 weeks (enabled by mandatory granulocyte-colony stimulating factor administration once daily for 6 days, starting on day 8; R-CHOP-14) without rituximab maintenance. Age, bulky disease (nodal or extranodal mass ≥10 cm in diameter on CT), and institution were used as adjustment factors. Investigators enrolled participants, and assignment to trial groups was done with a computer-assisted randomisation allocation sequence that took place centrally at the Japan Clinical Oncology Group Data Center, without the intervention of investigators. Interventions were not masked for patients or investigators. Data were collected 10 years after enrolment of the last patient. The primary endpoint of the phase 3 part of the study was progression-free survival, and the primary endpoint of the phase 2 part of the study was the proportion of patients who achieved a complete response. Accrual was 4·5 years, and follow-up was 3 years after registration was closed. Data were updated on the cutoff date of Feb 28, 2017. Intention-to-treat analyses (ie, progression-free survival, overall survival, and incidence of secondary malignancies) were predefined, to be done at 10 years after the last patient was enrolled. An additional analysis of the incidence of histological transformation was defined 15 years after the protocol, on May 8, 2017, in a supplementary analysis plan, and assessed at 10 years after the last patient was enrolled. Follow-up is ongoing. This trial is registered with ClinicalTrials.gov, number NCT00147121. Findings Between Sept 1, 2002, and Feb 28, 2007, 300 patients were enrolled, and 149 (50%) were assigned to the R-CHOP-21 group and 151 (50%) were assigned to the R-CHOP-14 group. After eligibility was assessed, one patient was excluded from the R-CHOP-21 group. 10-year progression-free survival was not different between groups (R-CHOP-21 33%, 95% CI 25–41; R-CHOP-14 39%, 31–47; hazard ratio 0·89, 95% CI 0·67–1·17). In 248 patients with grade 1–3a follicular lymphoma, progression-free survival was 39% (33–45) at 8 years and 36% (30–42) at 10 years. The cumulative incidence of histological transformation was 3·2% (95% CI 1·5–6·0) at 5 years, 8·5% (5·4–12·4) at 8 years, and 9·3% (6·1–13·4) at 10 years after enrolment. At 10 years, the cumulative incidence of secondary malignancies was 8·1% (5·1–12·0) and the cumulative incidence of haematological secondary malignancies was 2·9% (1·3–5·5). Interpretation R-CHOP is a viable option for first-line treatment in patients with newly diagnosed advanced follicular lymphoma. Clinicians choosing a first-line treatment for patients with follicular lymphoma should be cautious of secondary malignancies caused by immunochemotherapy and severe complications of infectious diseases in the long-term follow-up—both of which could lead to death. Funding National Cancer Center and Ministry of Health, Labour and Welfare of Japan.