Chromosome abnormalities in advanced stage T-cell lymphoblastic lymphoma of children and adolescents: a report from Japanese Paediatric Leukaemia/Lymphoma Study Group (JPLSG) and review of the literature

Diverse mutations and structural variations contribute to Notch signaling deregulation in paediatric T-cell lymphoblastic lymphoma

BACKGROUND

T-cell lymphoblastic lymphoma (T-LBL) is an aggressive neoplasm closely related to T-cell acute lymphoblastic leukaemia (T-ALL). Despite their similarities, and contrary to T-ALL, studies on paediatric T-LBL are scarce and, therefore, its molecular landscape has not yet been fully elucidated. Thus, the aims of this study were to characterize the genetic and molecular heterogeneity of paediatric T-LBL and to evaluate novel molecular markers differentiating this entity from T-ALL.

PROCEDURE

Thirty-three paediatric T-LBL patients were analyzed using an integrated approach, including targeted next-generation sequencing, RNA-sequencing transcriptome analysis and copy-number arrays.

RESULTS

Copy number and mutational analyses allowed the detection of recurrent homozygous deletions of 9p/CDKN2A (78%), trisomy 20 (19%) and gains of 17q24-q25 (16%), as well as frequent mutations of NOTCH1 (62%), followed by the BCL11B (23%), WT1 (19%) and FBXW7, PHF6 and RPL10 genes (15%, respectively). This genetic profile did not differ from that described in T-ALL in terms of mutation incidence and global genomic complexity level, but unveiled virtually exclusive 17q25 gains and trisomy 20 in T-LBL. Additionally, we identified novel gene fusions in paediatric T-LBL, including NOTCH1-IKZF2, RNGTT-SNAP91 and DDX3X-MLLT10, the last being the only one previously described in T-ALL. Moreover, clinical correlations highlighted the presence of Notch pathway alterations as a factor related to favourable outcome.

CONCLUSIONS

In summary, the genomic landscape of paediatric T-LBL is similar to that observed in T-ALL, and Notch signaling pathway deregulation remains the cornerstone in its pathogenesis, including not only mutations but fusion genes targeting NOTCH1.

Recent advances in T-cell lymphoid neoplasms

T Cells comprise many subtypes of specified lymphocytes, and their differentiation and function take place in different tissues. This cellular diversity is also observed in the multiple ways T-cell transformation gives rise to a variety of T-cell neoplasms. This review covers the main types of T-cell malignancies and their specific characteristics, emphasizing recent advances at the cellular and molecular levels as well as differences and commonalities among them.

Mediastinal Lymphoproliferative Disorders

Lymphoproliferative disorders comprise 50% to 60% of all mediastinal malignancies in both children and adults. Primary mediastinal involvement is rare (∼5%), whereas secondary mediastinal involvement by systemic disease is more common (10% to 25%). Primary mediastinal disease is defined as involvement by a lymphoproliferative disorder of mediastinal lymph nodes, the thymus, and/or extranodal mediastinal organs without evidence of systemic disease at presentation. In this review, the clinical, radiologic, histopathologic, immunohistochemical, and genetic features of some of the most characteristic mediastinal lymphoproliferative disorders are presented. The entities discussed here include: classic Hodgkin lymphoma with emphasis on nodular sclerosis and mixed cellularity types, and non-Hodgkin lymphomas, including primary mediastinal (thymic) large B-cell lymphoma, mediastinal gray zone lymphoma, mediastinal diffuse large B-cell lymphoma, thymic marginal zone lymphoma, mediastinal plasmacytoma, T-lymphoblastic lymphoma, and anaplastic large cell lymphoma. Although not a malignant process, hyaline vascular Castleman disease is also discussed here as this disorder commonly involves the mediastinum. Despite multiple advances in hematopathology in recent decades, the day-to-day diagnosis of these lesions still requires a morphologic approach and a proper selection of immunohistochemical markers. For this reason, it is crucial for general pathologists to be familiar with these entities and their particular clinicoradiologic presentation.

Acute Lymphoblastic Leukemia and Acute Lymphoblastic Lymphoma: Same Disease Spectrum but Two Distinct Diagnoses

PURPOSE OF REVIEW

Rare malignancies developing from lymphocyte precursor cells, lymphoblastic leukemia (LBL), and acute lymphoblastic lymphoma (ALL) have historically been viewed as different manifestations of the same disease process. This review examines data on their epidemiology, genetics, clinical presentation, and response to treatment while highlighting areas of similarity and divergence between these two clinical entities.

RECENT FINDINGS

Pediatric-type ALL chemotherapy regimens, compared to both lymphoma-type chemotherapy and adult-type ALL regimens, have led to improved outcomes for children, adolescents, and young adults with ALL. BCR-ABL-targeting tyrosine kinase inhibitors (TKIs) have improved outcomes in Philadelphia chromosome-positive (Ph +) ALL and in rare cases of Ph + LBL. Newer therapies including blinatumomab, inotuzumab, CAR-T therapy, and nelarabine have improved outcomes in selected cases of ALL and have an emerging role in the management of LBL. Better understanding of ALL and LBL biology allows for the development of therapies that target immunophenotypic or genetic features found in subsets of both diseases. Novel therapies are leading to improved outcomes in Ph + and relapsed and refractory disease.

Outcome of allogeneic hematopoietic stem cell transplantation for T-cell lymphoblastic leukemia/lymphoma: A single-center study

Although the indications for allogeneic hematopoietic stem cell transplantation (allo-HSCT) as a treatment for T-cell acute lymphoblastic leukemia/lymphoma (T-ALL/LBL) and Philadelphia chromosome (Ph)-negative B-cell acute lymphoblastic leukemia (B-ALL) are similar, few studies have compared its outcomes for T-ALL/LBL and Ph-negative B-ALL. The clinical data of 28 patients with T-ALL, 16 with T-LBL, and 99 with Ph-negative B-ALL who underwent the first allo-HSCT from 2000 to 2019 were retrospectively analyzed. Complete remission (CR) rates at allo-HSCT were 79 %, 63 %, and 75 % for T-ALL, T-LBL, and B-ALL, respectively; the 3-year overall survival (OS) rates were 55.7 %, 56.2 %, and 58.6 %, respectively (p = 0.92). Univariate analysis revealed that disease subtypes were not significantly associated with OS (B-ALL vs. T-ALL: hazard ratio [HR]=0.89, p = 0.70; T-LBL vs. T-ALL: HR=0.87, p = 0.75), and CR at allo-HSCT was the only prognostic factor for OS (HR=0.25, p < 0.001). Multivariate analysis demonstrated that CR at allo-HSCT was the only predictor of OS (HR=0.24, p < 0.001). In all three disease subtypes, patients in CR at allo-HSCT tended to have a lower cumulative incidence of relapse than did those in non-CR (T-ALL: 13.6 % vs. 50.0 %, p = 0.10; T-LBL: 20.0 % vs. 50.0 %, p = 0.21; B-ALL: 10.0 % vs. 56.0 %, p < 0.01). Thus, the outcomes of allo-HSCT for T-ALL/LBL were comparable to those of Ph-negative B-ALL. Irrespective of the disease subtypes, achieving CR before allo-HSCT was associated with a favorable OS. Further advances in chemotherapy before allo-HSCT and defining the optimal timing of allo-HSCT would improve the prognosis of patients with T-ALL/LBL.

T-cell lymphoblastic lymphoma and leukemia: different diseases from a common premalignant progenitor?

T-cell lymphoblastic lymphoma (T-LBL) and lymphoblastic leukemia (T-ALL) represent malignancies that arise from the transformation of immature precursor T cells. Similarities in T-LBL and T-ALL have raised the question whether these entities represent 1 disease or reflect 2 different diseases. The genetic profiles of T-ALL have been thoroughly investigated over the last 2 decades, whereas fairly little is known about genetic driver mutations in T-LBL. Nevertheless, the comparison of clinical, immunophenotypic, and molecular observations from independent T-LBL and T-ALL studies lent strength to the theory that T-LBL and T-ALL reflect different presentations of the same disease. Alternatively, T-LBL and T-ALL may simultaneously evolve from a common malignant precursor cell, each having their own specific pathogenic requirements or cellular dependencies that differ among stroma-embedded blasts in lymphoid tissues compared with solitary leukemia cells. This review aims to cluster recent findings with regard to clinical presentation, genetic predisposition, and the acquisition of additional mutations that may give rise to differences in gene expression signatures among T-LBL and T-ALL patients. Improved insight in T-LBL in relation to T-ALL may further help to apply confirmed T-ALL therapies to T-LBL patients.

Chromosome Translocation t(14;21)(q11;q22) Activates Both OLIG1 and OLIG2 in Pediatric T-cell Lymphoblastic Malignancies and May Signify Adverse Prognosis

BACKGROUND/AIM

The chromosome translocation t(14;21)(q11;q22) was reported in four pediatric T-cell lymphoblastic leukemias and was shown to activate the OLIG2 gene.

MATERIALS AND METHODS

A pediatric T-cell lymphoblastic lymphoma was investigated using G-banding chromosome analysis, fluorescence in situ hybridization (FISH), and immunocytochemistry.

RESULTS

The malignant cells carried a t(14;21)(q11;q22) aberration. The translocation moves the enhancer elements of TRA/TRD from band 14q11 to 21q22, a few thousands kbp downstream of OLIG1 and OLIG2, resulting in the production of both OLIG1 and OLIG2 proteins.

CONCLUSION

The translocation t(14;21)(q11;q22) occurs in some pediatric T-cell lymphoblastic malignancies. Activation of both OLIG1 and OLIG2 by t(14;21)(q11;q22) in T-lymphoblasts and the ensuing deregulation of thousands of genes could explain the highly malignant disease and resistance to treatment that has characterized this small group of patients.

DNA methylation and copy number variation profiling of T-cell lymphoblastic leukemia and lymphoma

Despite having common overlapping immunophenotypic and morphological features, T-cell lymphoblastic leukemia (T-ALL) and lymphoma (T-LBL) have distinct clinical manifestations, which may represent separate diseases. We investigated and compared the epigenetic and genetic landscape of adult and pediatric T-ALL (n = 77) and T-LBL (n = 15) patient samples by high-resolution genome-wide DNA methylation and Copy Number Variation (CNV) BeadChip arrays. DNA methylation profiling identified the presence of CpG island methylator phenotype (CIMP) subgroups within both pediatric and adult T-LBL and T-ALL. An epigenetic signature of 128 differentially methylated CpG sites was identified, that clustered T-LBL and T-ALL separately. The most significant differentially methylated gene loci included the SGCE/PEG10 shared promoter region, previously implicated in lymphoid malignancies. CNV analysis confirmed overlapping recurrent aberrations between T-ALL and T-LBL, including 9p21.3 (CDKN2A/CDKN2B) deletions. A significantly higher frequency of chromosome 13q14.2 deletions was identified in T-LBL samples (36% in T-LBL vs. 0% in T-ALL). This deletion, encompassing the RB1, MIR15A and MIR16-1 gene loci, has been reported as a recurrent deletion in B-cell malignancies. Our study reveals epigenetic and genetic markers that can distinguish between T-LBL and T-ALL, and deepen the understanding of the biology underlying the diverse disease localization.

Primary Mediastinal Nodal and Extranodal Non-Hodgkin Lymphomas: Current Concepts, Historical Evolution, and Useful Diagnostic Approach: Part 2

Primary mediastinal non-Hodgkin lymphomas (PM-NHLs) represent ∼5% of all non-Hodgkin lymphomas (NHLs) and comprise lymphomas of B-cell and T-cell origin. PM-NHLs are defined as involvement of mediastinal lymph nodes, thymus, and/or mediastinal organs (heart, lung, pleura, pericardium) by NHL without evidence of systemic disease at presentation. The clinical scenario is variable and depends on the lymphoma subtype. The radiologic presentation is also variable ranging from a mediastinal mass with or without superior vena cava syndrome, a pleural or a cardiac mass associated with effusion, or as an effusion only. The diagnosis of PM-NHLs can only be established by microscopic evaluation, and therefore, general pathologists should be aware of these tumors and familiar with their diagnostic approach. The most common anterior mediastinal NHLs (90% to 95%) are primary mediastinal (PM) large B-cell lymphoma and T-lymphoblastic lymphoma. Thymic marginal zone lymphoma and mediastinal gray zone lymphoma are very rare. The remainder PM-NHLs involving middle or posterior mediastinum include diffuse large B-cell lymphoma (DLBCL) and rare cases of T-cell lymphoma, including anaplastic large cell lymphoma and breast implant-associated anaplastic large cell lymphoma extending to the anterior mediastinum. Primary pleural and cardiac NHLs are mostly DLBCLs. Other rare subtypes of PM-NHLs include DLBCL associated with chronic inflammation/pyothorax-associated lymphoma, fibrin-associated DLBCL (both Epstein-Barr virus positive), and pleural and/or pericardial primary effusion lymphoma (human herpesvirus-8 positive/Epstein-Barr virus positive). We review the historical aspects, epidemiology, clinicoradiologic features, histopathology, immunohistochemistry, differential diagnosis, and relevant cytogenetic and molecular features of the remaining mediastinal B-cell lymphomas, including primary thymic marginal zone lymphoma of the mucosa-associated lymphoid tissue type, other PM small B-cell lymphomas, PM plasmacytoma, and the most relevant PM T-cell lymphomas.

Primary Cutaneous T-Cell Lymphoblastic Lymphoma: Case Report and Literature Review

Cutaneous involvement by precursor T-cell lymphoblastic leukemia/lymphoma (T-ALL/LBL) is rare, and almost all cases are seen in association with bone marrow, blood, and/or lymph node involvement. Presentation with isolated skin involvement is very rare. Literature review revealed only one case report of primary cutaneous T-cell LBL. We discuss here another patient diagnosed with primary cutaneous T-cell LBL at our institute. This patient was initially misdiagnosed as having peripheral T-cell lymphoma NOS. Cytogenetic analysis showed the CDKN2A deletion (−9p21×2) in addition to three intact copies of ABL1 (+9q34). Although she failed multiple lines of intensive chemotherapy, her disease remained confined to the skin. We believe that this presentation of T-LBL is underreported, and many patients are likely misdiagnosed as having high-grade cutaneous T-cell lymphomas. With this case and literature review, we would like to highlight the importance of keeping lymphoblastic lymphoma on the differential diagnosis of cutaneous T-cell lymphoma-like lesions to avoid delay in diagnosis and inappropriate treatment of this aggressive disease.

Outcome of adult T-lymphoblastic lymphoma depends on ALL-type chemotherapy, prognostic factors, and performance of allogeneic hematopoietic stem cell transplantation

To study the prognostic factors of adult patients with T-lymphoblastic lymphoma (T-LBL) and to evaluate therapeutic effects of acute lymphoblastic leukemia (ALL)-type chemotherapy in combination with allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients who achieved overall response (OR) with first line ALL-type chemotherapy.This was a retrospective study of 59 adult patients with T-LBL treated with hyper-fractionated administration of cyclophosphamide, vincristine, doxorubicin and dexamethasone/methotrexate (hyper-CVAD/MA) chemotherapy alone or in combination with allo-HSCT between June 2008 and October 2015. Complete response (CR) and OR rates were evaluated after the initial chemotherapy. Clinical characteristics and the risk factors associated with prognosis and overall survival (OS) were analyzed in all patients and the effects of allo-HSCT on OS were evaluated in patients who had achieved OR after initial chemotherapy.Forty-eight patients (81.4%) achieved OR by hyper-CVAD chemotherapy, among which, 22 patients (45.8%) further received allo-HSCT. The median follow-up was 31.5 months, ranging from 11 to 97 months. The 3-year OS and progression-free survival (PFS) were 45.7% and 45.0% for patients who achieved OR after chemotherapy and both 0 for patients who did not achieve OR (both P < .001). Three year OS and PFS were higher in patients who received chemotherapy + allo-HSCT than in patients who received chemotherapy alone (3-year OS: 72.8% vs 17.5%, P = .008; PFS: 65.1% vs 27.8%, P = 0.007). Shorter survival was independently associated with elevated lactic dehydrogenase (LDH), Ki-67≥75%, pleural effusion and no OR (all P < .05) in all patients. But shorter survival was only associated with elevated LDH level, leukocytosis (>10 G/L), and chemotherapy alone in patients who achieved OR (all P < .05).The mid-term outcomes of adult patients with T-LBL are associated with response to chemotherapy (in all patients) and performance of allo-HSCT (in patients who achieved OR). Allo-HSCT could be a feasible and effective consolidation therapy for adult T-LBL.

A childhood chemotherapy protocol improves overall survival among adults with T-lymphoblastic lymphoma

A broadly accepted standard treatment for adult T-lymphoblastic lymphoma (T-LBL) has not yet been defined. To address that issue, we retrospectively compared three chemotherapy regimens used to treat 110 adult patients with newly diagnosed T-LBL. These included two adult regimens (ECOG2993 and hyper-CVAD) and a childhood regimen (BFM-90). These intensive drug regimens are mainly used to treat childhood and adult acute lymphoblastic leukemia. They included induction, consolidation, and maintenance chemotherapy protocols and were administered over the course of 2 years. Seventy-five patients (80%) achieved a complete remission (CR). Within a median follow-up time of 31 months (range: 5–152 months), the 5-year overall survival (OS) and progression-free survival (PFS) rates were 47.7% (95% CI, 35.0–69.8%) and 45.7% (95% CI, 27.6–56.6%), respectively. Shorter survival was associated with age > 40 years, poor ECOG PS and bone marrow involvement. Elevated lactic dehydrogenase (LDH) level, Ann Arbor stage and International Prognostic Index (IPI) score had no prognostic value. The childhood chemotherapy regimen improved CR and the overall survival rate more than the adult regimen in patients aged < 40 years.

Molecular genetics of childhood, adolescent and young adult non-Hodgkin lymphoma

Molecular genetic abnormalities are ubiquitous in non-Hodgkin lymphoma (NHL), but genetic changes are not yet used to define specific lymphoma subtypes. Certain recurrent molecular genetic abnormalities in NHL underlie molecular pathogenesis and/or are associated with prognosis or represent potential therapeutic targets. Most molecular genetic studies of B- and T-NHL have been performed on adult patient samples, and the relevance of many of these findings for childhood, adolescent and young adult NHL remains to be demonstrated. In this review, we focus on NHL subtypes that are most common in young patients and emphasize features actually studied in younger NHL patients. This approach highlights what is known about NHL genetics in young patients but also points to gaps that remain, which will require cooperative efforts to collect and share biological specimens for genomic and genetic analyses in order to help predict outcomes and guide therapy in the future.

Prognostic Impact of Intensified Maintenance Therapy on Children With Advanced Lymphoblastic Lymphoma: A Report From the Japanese Pediatric Leukemia/Lymphoma Study Group ALB-NHL03 Study

BACKGROUND

Childhood advanced lymphoblastic lymphoma (LBL) has a favorable outcome with an event-free survival (EFS) rate of over 80% in response to treatment strategies for acute lymphoblastic leukemia (ALL). However, no progress has been made in this outcome over the past 10 years.

PROCEDURE

We conducted the first nationwide prospective study of childhood advanced LBL to assess the efficacy and safety of ALL-directed therapy with an intensified maintenance phase. We omitted local radiotherapy including prophylactic cranial radiotherapy except for patients with initial central nervous system disease. The total duration of the treatment was 24 months.

RESULTS

For the 136 patients analyzed in this study, 5-year overall survival (OS) was 82.9% and 5-year EFS was 77.9%. Thirty events were observed and 14 occurred before the initiation of intensified maintenance phase. Of 14 events, nine were observed as mediastinal enlargement. There was no significant difference in outcome when stratified according to gender or by immunophenotype. The 5-year EFS according to clinical stage in patients with T-cell LBL (T-LBL) was 70.6% for stage III and 88.9% for stage IV (P = 0.037).

CONCLUSIONS

Our first nationwide study provided about 80% cure rate with only one case of toxic death in childhood advanced LBL. However, our intensified maintenance therapy could not improve the survival outcome. There was a trend of better EFS in Japanese patients with T-LBL stage IV than T-LBL stage III.

Treatment outcome in T-cell lymphoblastic lymphoma in adults - a population-based study from the Swedish Lymphoma Registry

BACKGROUND

T-cell lymphoblastic lymphoma (T-LBL) is a rare neoplasm of precursor lymphoblast origin, for which there is no standard treatment for adults. Results of current treatment strategies in selected populations do exist but are largely unreported for unselected series. Here, we aimed to investigate treatment outcome in a population-based cohort.

MATERIAL AND METHODS

Patients were identified through the Swedish Lymphoma Registry and data was retrospectively collected for all adult (≥ 18 years) Swedish T-LBL patients diagnosed during 2000-2009.

RESULTS

A total of 39 patients with median age 40 years (range 18-78) were identified with females being significantly older than males (median age 66 vs. 37, p = 0.027). The five-year overall survival for all patients was 42%. Female gender was associated with shorter survival also when adjusted for treatment strategy and age [hazard ratio (HR) 4.29; p = 0.002]. Thirty patients received intensive chemotherapy, otherwise used for treatment of acute lymphoblastic leukemia (ALL), which resulted in an overall response rate of 97% and a five-year progression-free survival (PFS) of 49%. In this group only CNS involvement at diagnosis predicted shorter PFS (HR 13.3; p = 0.03). Among patients treated with hyper-CVAD the addition of mediastinal irradiation resulted in prolonged time to progression compared to patients receiving only chemotherapy (p = 0.047). The major reason for treatment failure was relapse and in this series 18-fluoro-deoxyglucose positron emission tomography (PET) did not predict this risk.

CONCLUSION

This population-based study indicates that all fit T-LBL patients should be considered for intensive treatment. Our results also suggest a beneficial effect of mediastinal irradiation in combination with hyper-CVAD treatment. Relapsing patients have a dismal outcome irrespective of salvage treatment.

Biomarkers in childhood non-Hodgkin's lymphomas

Pediatric non-Hodgkin's lymphomas (NHLs) are a heterogeneous group of malignancies with distinct clinical, pathological, immunological and genetic characteristics. More than 90% of pediatric NHLs belong to one of three major histological subtypes: mature B-cell neoplasms, lymphoblastic lymphomas and anaplastic large-cell lymphomas. The recognition that different subtypes require different treatment regimens resulted in therapeutic strategies leading to over 80% of patients being cured. On the other hand, patients with resistant or relapsed disease have a poor prognosis. Prognostic biomarkers have not yet been identified for all pediatric NHLs and, although some are very important for diagnosis and prognosis, others may be of questionable value. Discovery of new biomarkers suitable for clinical application may aid the diagnosis and classification of lymphomas, which should, in turn, lead to better patient stratification. Consequent development of new treatment and follow-up approaches should lead to more efficient and less toxic treatment in children with NHL.