Fluorescent nanoparticle-mediated semiquantitative MYC protein expression analysis in morphologically diffuse large B-cell lymphoma.

The current World Health Organization (WHO) classification defines a new disease entity of high-grade B-cell lymphoma with MYC and BCL2 and/or BCL6 rearrangements, making fluorescence in situ hybridization (FISH) screening for these genes mandatory. In addition, the prognostic significance of MYC expression was reported, with a cut-off value of 40%. However, interobserver discrepancies arise due to the heterogeneous intensity of MYC expression by immunohistochemistry. Moreover, a cut-off value of positivity for MYC protein in diffuse large B-cell lymphoma (DLBCL) varies among studies at present. Here, we applied a high-sensitivity semiquantitative immunohistochemical technique using fluorescent nanoparticles called phosphor-integrated dots (PID) to evaluate the MYC expression in 50 de novo DLBCL cases, and compared it with the conventional diaminobenzidine (DAB)-developing system. The high MYC expression detected by the PID-mediated system predicted poor overall survival in DLBCL patients. However, we found no prognostic value of MYC protein expression for any cut-off value by the DAB-developing system, even if the intensity was considered. These results indicate that the precise evaluation of MYC protein expression can clarify the prognostic values in DLBCL, irrespective of MYC rearrangement.

Abemaciclib, a CDK4/6 inhibitor, exerts preclinical activity against aggressive germinal center-derived B-cell lymphomas.

The revised WHO classification newly defined the entities "High-grade B-cell lymphoma with MYC and BCL2, and/or BCL6 rearrangements (HGBL-DH/TH)" and "HGBL, NOS." Standard immunochemotherapy for diffuse large B-cell lymphoma (DLBCL), R-CHOP, is insufficient for HGBL patients, and there are currently no optimized therapeutic regimens for HGBL. We previously reported that CCND3, which encodes cyclin D3, harbored high mutation rates in Burkitt lymphoma (BL), HGBL and a subset of DLBCL. Furthermore, the knockdown of cyclin D3 expression was toxic to germinal center (GC)-derived B-cell lymphomas. Thus, the fundamental function of cyclin D3 is important for the pathogenesis of GC-derived B-cell lymphoma. We herein used two structurally different CDK4/6 inhibitors, palbociclib and abemaciclib, and examined their suppressive effects on cell proliferation and their ability to induce apoptosis in various aggressive B-cell lymphoma cell lines. The results obtained demonstrated that abemaciclib more strongly suppressed cell proliferation and induced apoptosis in GC-derived B-cell lymphoma cell lines than the control, but only slightly inhibited those features in activated B-cell (ABC)-like DLBCL cell lines. Palbociclib exerted partial or incomplete effects compared with the control and the effect was intermediate between abemaciclib and the control. Moreover, the effects of abemaciclib appeared to depend on cyclin D3 expression levels based on the results of the expression analysis of primary aggressive B-cell lymphoma samples. Therefore, abemaciclib has potential as a therapeutic agent for aggressive GC-derived B-cell lymphomas.

R-CHOP-14 versus R-CHOP-14/CHASER for upfront autologous transplantation in diffuse large B-cell lymphoma: JCOG0908 study.

The efficiency of upfront consolidation with high-dose chemotherapy/autologous stem-cell transplantation (HDCT/ASCT) for newly diagnosed high-risk diffuse large B-cell lymphoma (DLBCL) may be influenced by induction chemotherapy. To select better induction chemotherapy regimens for HDCT/ASCT, a randomized phase II study was conducted in high-risk DLBCL patients having an age-adjusted International Prognostic Index (aaIPI) score of 2 or 3. As induction chemotherapy, 6 cycles of R-CHOP-14 (arm A) or 3 cycles of R-CHOP-14 followed by 3 cycles of CHASER (arm B) were planned, and patients who responded proceeded to HDCT with LEED and ASCT. The primary endpoint was 2-y progression-free survival (PFS), and the main secondary endpoints included overall survival, overall response rate, and adverse events (AEs). In total, 71 patients were enrolled. With a median follow-up of 40.3 mo, 2-y PFS in arms A and B were 68.6% (95% confidence interval [CI], 50.5%-81.2%) and 66.7% (95% CI: 48.8%-79.5%), respectively. Overall survival at 2 y in arms A and B was 74.3% (95% CI: 56.4%-85.7%) and 83.3% (95% CI: 66.6%-92.1%). Overall response rates were 82.9% in arm A and 69.4% in arm B. During induction chemotherapy, 45.7% and 75.0% of patients in arms A and B, respectively, had grade ≥ 3 non-hematologic toxicities. One patient in arm A and 6 in arm B discontinued induction chemotherapy due to AEs. In conclusion, R-CHOP-14 showed higher 2-y PFS and less toxicity compared with R-CHOP-14/CHASER in patients with high-risk DLBCL, suggesting the former to be a more promising induction regimen for further investigations (UMIN-CTR, UMIN000003823).

Anaplastic large cell lymphoma with TP63 rearrangement: A dismal prognosis.

Anaplastic large cell lymphoma (ALCL) with TP63 rearrangement is a new entity and has the most dismal prognosis in all types of ALCL. This might be due to the resulting fusion protein having N-terminal truncated p63 with high oncogenic ability. Since this N-terminal domain has the function of tumor suppressor activity, the mechanism for high oncogenic capacity is thought to be the dominant negative function. Here, we report two ALCL cases with TP63 rearrangement that was each given too short a prognosis (Case 1 and 2: four and six months) in spite of intensive treatment. Immunohistochemically, p63 was highly expressed, and a sprit signal was detected using a TP63 break apart fluorescence in situ hybridization (FISH) in each case. Additionally, a poor prognostic marker of ALCL, all cytotoxic molecules (TIA-1, Granzyme B, and Perforin) were also expressed in almost all ALCL cells. Taken together, we suggest that not only the dominant negative function of N-truncated p63 but also the effect of cytotoxic molecules may influence the dismal prognosis of ALCL with TP63 rearrangement.

[Methotrexate-associated lymphoproliferative disorders: clinical aspects].

Methotrexate-associated lymphoproliferative disorders (MTX-LPD) is categorized into other iatrogenic immunodeficiency-associated lymphoproliferative disorders, developing LPD in patients with autoimmune diseases (AIDs) under low dose MTX administration. Two-thirds of MTX-LPDs regresses after MTX withdrawal with the higher incidence in Japanese patients, MTX-LPDs consist of various subtypes of LPDs, the feature of each LPD such as the regressive rate, relapse/regrowth rate, and prognosis, widely varies. The absolute lymphocyte count (ALC) in peripheral blood is suggested to influence LPD development, regression, and relapse/regrowth events. Because various factors might effect the pathogenesis and clinical features of MTX-LPD, careful attention should be paid to assess MTX-LPD.

Treatment-free remission after two-year consolidation therapy with nilotinib in patients with chronic myeloid leukemia: STAT2 trial in Japan.

The purpose of this trial was to evaluate the efficacy of 2-year consolidation therapy with nilotinib, at a dose of 300 mg twice daily, for achieving treatment-free remission in chronic myeloid leukemia patients with a deep molecular response (BCR-ABL1IS ≤0.0032%). Successful treatment-free remission was defined as no confirmed loss of deep molecular response. We recruited 96 Japanese patients, of whom 78 sustained a deep molecular response during the consolidation phase and were therefore eligible to discontinue nilotinib in the treatment-free remission phase; of these, 53 patients (67.9%; 95% confidence interval: 56.4-78.1%) remained free from molecular recurrence in the first 12 months. The estimated 3-year treatment-free survival was 62.8%. Nilotinib was readministered to all patients (n=29) who experienced a molecular recurrence during the treatment-free remission phase. After restarting treatment, rapid deep molecular response returned in 25 patients (86.2%), with 50% of patients achieving a deep molecular response within 3.5 months. Tyrosine kinase inhibitor withdrawal syndrome was reported in 11/78 patients during the early treatment-free remission phase. The treatment-free survival curve was significantly better in patients with undetectable molecular residual disease than in patients without (3-year treatment-free survival, 75.6 versus 48.6%, respectively; P=0.0126 by the log-rank test). There were no significant differences in treatment-free survival between subgroups based on tyrosine kinase inhibitor treatment before the nilotinib consolidation phase, tyrosine kinase inhibitor-withdrawal syndrome, or absolute number of natural killer cells. The results of this study indicate that it is safe and feasible to stop tyrosine kinase inhibitor therapy in patients with chronic myeloid leukemia who have achieved a sustained deep molecular response with 2 years of treatment with nilotinib. This study was registered with UMIN-CTR (UMIN000005904).

Features of vascular adverse events in Japanese patients with chronic myeloid leukemia treated with tyrosine kinase inhibitors: a retrospective study of the CML Cooperative Study Group database.

This study investigated the incidence rate and features of vascular adverse events (VAEs) in Japanese patients with chronic myeloid leukemia (CML) who were treated with tyrosine kinase inhibitors (TKIs). The analysis included 369 CML patients in the chronic or accelerated phases, selected from the CML Cooperative Study Group database; 25 events in 23 (6.2%) of these patients were VAEs. At the time of VAE incidence, nine patients were on treatment with imatinib, 12 with nilotinib, three with dasatinib, and one with bosutinib. VAE incidence comprised 13 cases of ischemic heart disease (IHD), eight of cerebral infarction (CI), and four of peripheral arterial occlusive disease (PAOD). IHD incidence rate in the study population was higher than that in the age-matched general population, particularly in nilotinib-treated patients, while CI incidence rate was almost equivalent. Compared with the Suita score, the SCORE chart and the Framingham score risk assessment tools detected more patients with high or very high risk of VAEs. In conclusion, incidence of IHD requires closer monitoring in nilotinib-treated patients. More detailed investigations for determining the most useful tool to predict VAE incidence and long-term analysis of therapy-related VAE cases are needed for improving safety during TKI therapy.

[Human parvovirus B19-induced hemophagocytic lymphohistiocytosis and myocarditis in an adult patient with hereditary spherocytosis].

Human parvovirus B19 (HPV-B19) causes hemophagocytic lymphohistiocytosis (HLH). Here we describe a 35-year-old female with hereditary spherocytosis (HS) who developed HLH due to HPV-B19 infection. Upon admission, she had high fever and diarrhea. Laboratory findings included severe pancytopenia and elevated serum triglyceride and ferritin levels. Moreover, high HPV-B19 levels in the peripheral blood and increased reactive lymphocytosis in the bone marrow led to a diagnosis of HLH due to HPV-B19 infection. With supportive therapy and a blood transfusion, HLH symptoms, including fever and myelosuppression, improved in 1 week. However, symptoms of heart failure (HF) suddenly developed, and an echocardiography revealed diffuse systolic dysfunction, suggesting viral myocarditis due to HPV-B19 infection. Conservative management with diuretics gradually improved HF symptoms over a period of 2 weeks. HPV-B19 infection in adult patients with HS rarely results in severe HLH, but conservative therapy may improve the symptoms. Nonetheless, a careful follow-up is required after HLH improves because viral myocarditis can develop, as was seen in our patient.

Distinct patterns of lymphocyte count transition in lymphoproliferative disorder in patients with rheumatoid arthritis treated with methotrexate.

Objective: To clarify the characteristics of lymphoproliferative disorder (LPD) in patients with RA treated with MTX. Methods: Among 33 patients developing LPD during MTX treatment, 20 LPDs regressed spontaneously within 12 weeks after MTX cessation (regressive LPD), and 13 did not regress and most of them died or needed chemotherapy (persistent LPD). The control group consisted of 66 clinically matched MTX-treated RA patients without LPD. The clinical characteristics were compared between these three groups. Results: While no significant differences were found in clinical RA and LPD features among the three groups, the absolute lymphocyte number of the two LPD groups at LPD diagnosis was significantly lower than the control group (497/µl in the regressive vs 680/µl in the persistent vs 1400/µl in the control, P < 0.05). After MTX withdrawal, the lymphocyte number in the regressive group rapidly recovered to 1214/µl (P < 0.01) by week 2 and was thereafter maintained at an equivalent level to the control group. In contrast, lymphocyte level in the persistent group did not show significant increase throughout 12 weeks (620/µl at week 2, P = 0.57). Changes in lymphocyte number following MTX withdrawal clearly distinguished the regressive LPD from the persistent LPD. Conclusion: A significant decrease in lymphocyte count at the LPD diagnosis and its restoration after MTX withdrawal were markedly associated with spontaneous regression of LPD developing during MTX treatment.

Mechanisms of drug resistance and sensitivity concerning novel agents for multiple myeloma.

Multiple myeloma (MM) is a neoplastic plasma-cell disorder characterized by clonal proliferation of malignant plasma cells in the bone marrow microenvironment. Novel treatments such as proteasome inhibitors and immunomodulatory agents significantly prolong both progression free survival and overall survival (OS) in patients with MM. However, recent clinical data have indicated that it is difficult to eradicate all MM clones even with the administration of such novel agents. To overcome drug resistance (DR), further investigation of the mechanism underlying DR is required, and strategies to up-regulate, maintain, and restore drug sensitivity will become increasingly important in the clinical setting. The findings from basic research focusing on the microenvironment, genetic abnormalities, and signal transduction disturbances related to MM pathogenesis are excellent strategies for developing new agents. In addition, based on the improved OS over 10 years and the low continuation rate of standard therapy in frail patients, a stratified strategy has the potential to provide total therapy.

TM-233, a novel analog of 1'-acetoxychavicol acetate, induces cell death in myeloma cells by inhibiting both JAK/STAT and proteasome activities.

Although the introduction of bortezomib and immunomodulatory drugs has led to improved outcomes in patients with multiple myeloma, the disease remains incurable. In an effort to identify more potent and well-tolerated agents for myeloma, we have previously reported that 1'-acetoxychavicol acetate (ACA), a natural condiment from South-East Asia, induces apoptotic cell death of myeloma cells in vitro and in vivo through inhibition of NF-κB-related functions. Searching for more potent NF-κB inhibitors, we developed several ACA analogs based on quantitative structure-activity relationship analysis. TM-233, one of these ACA analogs, inhibited cellular proliferation and induced cell death in various myeloma cell lines with a lower IC50 than ACA. Treatment with TM-233 inhibited constitutive activation of JAK2 and STAT3, and then downregulated the expression of anti-apoptotic Mcl-1 protein, but not Bcl-2 and Bcl-xL proteins. In addition, TM-233 rapidly decreased the nuclear expression of NF-κB and also decreased the accumulation of cytosolic NF-κB. We also examined the effects of TM-233 on bortezomib-resistant myeloma cells that we recently established, KMS-11/BTZ and OPM-2/BTZ. TM-233, but not bortezomib, inhibited cellular proliferation and induced cell death in KMS-11/BTZ and OPM-2/BTZ cells. Interestingly, the combination of TM-233 and bortezomib significantly induced cell death in these bortezomib-resistant myeloma cells through inhibition of NF-κB activity. These results indicate that TM-233 could overcome bortezomib resistance in myeloma cells mediated through different mechanisms, possibly inhibiting the JAK/STAT pathway. In conclusion, TM-233 might be a more potent NF-κB inhibitor than ACA, and could overcome bortezomib resistance in myeloma cells.

[Cardiac and breast diffuse large B-cell lymphoma with pericardial effusion and AV-block].

Primary cardiac lymphoma is extremely rare and is associated with a poor prognosis. In most cases, cardiac involvement occurs as a late symptom and the diagnosis is thus delayed. We herein report a 35-year-old woman with cardiac diffuse large B-cell lymphoma (DLBCL) with breast infiltration. The patient was admitted to our hospital based on an initial presentation with dyspnea on exertion, chest pain, and a hard mass of the left breast. Echocardiography revealed a mass in the right atrium wall and interatrial septum, and massive pericardial effusion. ECG showed atrioventoricular block. We promptly performed a needle biopsy of the breast mass, which showed CD5-positive DLBCL, non-GCB type. The serum HIV reaction was negative. We thus diagnosed this patient as having cardiac and breast CD5-positive DLBCL, stage IVA, based on the massive pericardial effusion. The patient's prognosis was apparently poor. Therefore, she received 3 cycles of R-CHOP chemotherapy followed by autologous peripheral blood stem cell transplantation (PBSCT), resulting in a complete response. In general, cardiac lymphoma is associated with high mortality and has a poor prognosis. This case demonstrates that rapid and appropriate diagnosis, and immediate intensive chemotherapy followed by PBSCT might be necessary for the treatment of extranodal lymphoma indicative of a poor prognosis.

Copy Number Analysis of 9p24.1 in Classic Hodgkin Lymphoma Arising in Immune Deficiency/Dysregulation.

A subset of patients with rheumatoid arthritis receiving methotrexate develop immune deficiencies and dysregulation-associated lymphoproliferative disorders. Patients with these disorders often exhibit spontaneous regression after MTX withdrawal; however, chemotherapeutic intervention is frequently required in patients with classic Hodgkin lymphoma arising in immune deficiency/dysregulation. In this study, we examined PD-L1 expression levels and 9p24.1 copy number alterations in 27 patients with classic Hodgkin lymphoma arising from immune deficiency/dysregulation. All patients demonstrated PD-L1 protein expression and harbored 9p24.1 copy number alterations on the tumor cells. When comparing clinicopathological data and associations with 9p24.1 copy number features, the copy gain group showed a significantly higher incidence of extranodal lesions and clinical stages than the amplification group. Notably, all cases in the amplification group had latency type II, while 6/8 (75%) in the copy gain group had latency type II, and 2/8 (25%) had latency type I. Thus, a subset of the copy-gain group demonstrated more extensive extranodal lesions and higher clinical stages. This finding speculates the presence of a genetically distinct subgroup within the group of patients who develop immune deficiencies and dysregulation-associated lymphoproliferative disorders, which may explain certain characteristic features.

Changes in chronic myeloid leukemia treatment modalities and outcomes after introduction of second-generation tyrosine kinase inhibitors as first-line therapy: a multi-institutional retrospective study by the CML Cooperative Study Group.

This study investigated changes in treatment modalities and outcomes of chronic myeloid leukemia in the chronic phase (CP-CML) after the approval of second-generation tyrosine kinase inhibitors (2G-TKIs) for first-line therapy. Patients were grouped into those who underwent TKI therapy up to December 2010 (imatinib era group, n = 185) and after January 2011 (2G-TKI era group, n = 425). All patients in the imatinib era group were initially treated with imatinib, whereas patients in the 2G-TKI era group were mostly treated with dasatinib (55%) or nilotinib (36%). However, outcomes including progression-free survival, overall survival, and CML-related death (CRD) did not differ significantly between groups. When stratified by risk scores, the prognostic performance of the ELTS score was superior to that of the Sokal score. Even though both scoring systems predicted CRD in the imatinib era, only the ELTS score predicted CRD in the 2G-TKI era. Notably, the outcome of patients classified as high-risk by ELTS score was more favorable in the 2G-TKI era group than in the imatinib era group. Thus, expanding treatment options may have improved patient outcomes in CP-CML, particularly in patients classified as high-risk by ELTS score.

Clinical management of second-generation tyrosine kinase inhibitor therapy in patients with newly diagnosed chronic myeloid leukemia in the chronic phase, focusing on age and dose effects.

ABL1-tyrosine kinase inhibitors (TKIs) are an established treatment choice for patients with chronic myeloid leukemia in the chronic phase (CML-CP). However, effects of TKI dose modification have not been well investigated. In this study, we retrospectively analyzed 178 patients with newly diagnosed CML-CP who were treated with dasatinib or nilotinib, focusing on age and dose effects. Efficacy as measured by cumulative major molecular response (MMR) and molecular response 4.5 rates did not differ significantly between the younger group and elderly group. Elderly patients who started nilotinib at a reduced dose had similar or better efficacy outcomes (including cumulative MMR and continuation ratios) than other groups, and elderly patients who started dasatinib at a reduced dose had the lowest MMR ratio and longest MMR duration. Effects of dose modification based on age and TKI selection can be attributed to flexible management of TKI therapy in real-world practice, but further studies are required to validate the findings of this study.

Management and Risk Factors for Pleural Effusion in Japanese Patients with Chronic Myeloid Leukemia Treated with First-line Dasatinib in Real-world Clinical Practice.

Objective Pleural effusion (PE) is a common adverse event that occurs during dasatinib therapy for chronic myeloid leukemia (CML). However, the pathomechanism of PE and appropriate management of Asian patients with CML have not been elucidated. This study investigated the incidence rate, risk, and appropriate management of PE in Asian patients with CML treated with dasatinib. Methods We retrospectively collected data on patients in the chronic phase of CML who received first-line dasatinib therapy and were registered in the CML-Cooperative Study Group database. Patients We identified 44 cases of PE in a series of 89 patients and analyzed previously reported risk factors and effective management of PE. Results A univariate analysis revealed that age, diabetes mellitus, chronic renal failure, hypertension, the history of cardiovascular events, and dasatinib dose were significantly associated with PE. A multivariate analysis revealed that age ≥65 years old was the only independent risk factor for PE. Dasatinib dose reduction and switching to a tyrosine kinase inhibitor showed a statistically significant difference in effectively reducing PE volume compared to single diuretic use. Conclusion Although further studies are warranted, our observations showed that advanced age is a significant risk factor for PE, and tyrosine kinase inhibitor dose reduction or replacement of dasatinib may be an effective management strategy for PE in Asian CML patients who received first-line treatment with dasatinib in real-world clinical practice.

Rapid deterioration of intravascular large B-cell lymphoma with mass formation in the trigeminal nerve and multiple organ infiltration: An autopsy case report.

Intravascular large B-cell lymphoma (IVLBCL) is a rare lymphoma characterized by the selective growth of lymphoma cells within the lumen of vessels. We describe the case of a 69-year-old male who presented with marked pain in the left facial region. Gadolinium-enhanced magnetic resonance imaging revealed a swollen left trigeminal nerve (TN) and positron emission tomography/computed tomography demonstrated fluorodeoxyglucose-only uptake at the same site. The patient had high serum lactate dehydrogenase and soluble interleukin-2 receptor levels. As random skin biopsy and bone marrow biopsy detected no abnormal pathogenesis, open biopsy of the TN was performed, revealing diffuse large B-cell lymphoma (DLBCL). However, ground glass opacities rapidly developed in both lung fields with severe respiratory failure. The patient died of progressive disease before the initiation of chemotherapy. Postmortem examination revealed widespread lymphoma cells in the lumen of vessels in multiple organs, including the lungs, excluding the bone marrow and skin. Lymphoma cells formed a mass in the TN and left lumbar plexus. A diagnosis of IVLBCL was made based on the postmortem pathological analysis. DLBCL of abnormal sites, such as the peripheral nervous system, should be considered in cases of IVLBCL as a differential diagnosis.

CD24 is a surrogate for 'immune-cold' phenotype in aggressive large B-cell lymphoma.

The tumor microenvironment (TME) is a critical regulator of the development of malignant lymphoma. Therapeutics targeting the TME, especially immune checkpoint molecules, are changing the treatment strategy for lymphoma. However, the overall response to these therapeutics for diffuse large B-cell lymphoma (DLBCL) is modest and new targets of immunotherapy are needed. To find critical immune checkpoint molecules for DLBCL, we explored the prognostic impact of immune checkpoint molecules and their ligands using publicly available datasets of gene expression profiles. In silico analysis of three independent datasets (GSE117556, GSE10846, and GSE181063) revealed that DLBCL expressing CD24 had a poor prognosis and had a high frequency of MYC aberrations. Moreover, gene set enrichment analysis showed that the 'MYC-targets-hallmark' (false discovery rate [FDR] = 0.024) and 'inflammatory-response-hallmark' (FDR = 0.001) were enriched in CD24-high and CD24-low DLBCL, respectively. In addition, the expression of cell-specific markers of various immune cells was higher in CD24-low DLBCL than in CD24-high DLBCL. CIBERSORT analysis of the datasets showed fewer macrophages in CD24-high DLBCL than in CD24-low DLBCL. Additionally, immunohistochemical analysis of 335 cases of DLBCL showed that few TME cells were found in CD24-high DLBCL, although statistical differences were not observed. These data indicate that CD24 expression suppresses immune cell components of the TME in DLBCL, suggesting that CD24 may be a target for cancer immunotherapy in aggressive large B-cell lymphoma.

Outcomes of adolescents and young adults with chronic-phase chronic myeloid leukaemia treated with tyrosine kinase inhibitors.

INTRODUCTION: Few studies have reported the outcomes of adolescents and young adults (AYAs) with chronic-phase chronic myeloid leukaemia (CML-CP) on tyrosine kinase inhibitors (TKIs). MATERIALS AND METHODS: We retrospectively analysed the clinical features, treatment response, and long-term outcomes of 42 AYA patients, in comparison to older patients. The initial therapies of AYA patients between 2001 and 2016 included imatinib (n = 24), dasatinib (n = 13) and nilotinib (n = 5). RESULTS: In AYA patients, the peripheral blood (PB) white blood cell count and percentage of blasts at the diagnosis were significantly higher, haemoglobin levels were lower and the spleen size was larger. The major molecular response (MMR), event-free survival (EFS) and overall survival (OS) rates were comparable. A sub-analysis comparing imatinib to second-generation TKIs as the initial therapy also showed that their prognosis was comparable. DISCUSSION: In conclusion, the tumour burden at the diagnosis of CML-CP is higher in AYA patients; however, their prognosis was not worse in comparison to older patients treated with TKIs. KEY MESSAGESFew studies have reported the outcomes of adolescents and young adults (AYAs) with chronic-phase chronic myeloid leukaemia (CML-CP) on tyrosine kinase inhibitors (TKIs). This study showed the tumour burden at the diagnosis of CML-CP is higher in AYA pa tients; however, their prognosis was not worse in comparison to older patients treated with TKIs. Understanding the biological and non-biological features of AYA patients with CML-CP on TKI therapy is essential for better management and to improve the outcomes.