Comprehensive analysis of clinical, pathological, and genomic characteristics of follicular helper T-cell derived lymphomas

Immunophenotypic classification regarding prognosis in peripheral T cell lymphoma, NOS, and nodal T follicular helper T cell lymphoma, angioimmunoblastic-type

This study aimed to determine the clinicopathological predictive factors of peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS), and nodal T-follicular helper cell lymphoma, angioimmunoblastic-type (nTFH, AI-type). In this single-centered, retrospective study, medical records of 59 patients who were diagnosed with PTCL, NOS, or nTFH, AI-type from March 2007 to September 2022 were reviewed. The clinicopathological variables, including immunohistochemistry(IHC) subgroups, distinguishing TBX21 from the GATA3 subgroups were analyzed. Overall, 28 patients (75.7%) in the TBX21 group were PTCL, NOS. There were 9 (24.3%) patients in the GATA3 group. In univariable analyses, lymphoma subtype, age, and performance status were associated with progression-free survival (PFS), and overall survival (OS). In multivariable analyses, lymphoma subtype, and performance status were related to PFS and OS (P = 0.012, P < 0.001, P = 0.006, and P < 0.001, respectively). The GATA3 subgroup tended to have a worse prognosis in univariable analyses; however, it became more insignificant in multivariable when lymphoma subtype and performance status were adjusted (P = 0.065, P = 0.180, P = 0.972, and P = 0.265, respectively). The double-positive group showed variable prognoses of better PFS and worse OS. PD-1 and PD-L1 were associated with the EBV in situ hybridization (P = 0.027, and P = 0.005), and PD-1 was associated with CD30 expression (P = 0.043). This study demonstrated the potential of IHC classification to predict prognosis for PTCL, NOS, as well as nTFH AI-type, although further validation is necessary. Treatments targeting CD30, PD-1, and PD-L1 appear promising for lymphoma treatment.

Clinicopathologic analysis of nodal T-follicular helper cell lymphomas, a multicenter retrospective study from China

Background

Nodal T-follicular helper cell lymphomas (nTFHLs) represent a new family of peripheral T-cell lymphomas (PTCLs), and comparative studies of their constituents are rare.

Methods

This study retrospectively enrolled 10 patients with nTFHL-F and 30 patients with nTFHL-NOS diagnosed between December 2017 and October 2023 at six large comprehensive tertiary hospitals; 188 patients with nTFHL-AI were diagnosed during the same period at the First Affiliated Hospital of Zhengzhou University for comparison.

Results

Compared with nTFHL-AI, nTFHL-NOS patients exhibited better clinical manifestations, lower TFH expression levels, and a lower Ki-67 index. However, no differences in clinicopathological features were observed between nTFHL-F and nTFHL-AI patients as well as nTFHL-NOS patients. According to the survival analysis, the median OS for patients with nTFHL-NOS, nTFHL-AI, and nTFHL-F were 14.2 months, 10 months, and 5 months, respectively, whereas the median TTP were 14 months, 5 months, and 3 months, respectively. Statistical analysis revealed differences in TTP among the three subtypes(P=0.0173). Among the population of patients receiving CHOP-like induction therapy, there were significant differences in the OS and TTP among the nTFHL-NOS, nTFHL-AI, and nTFHL-F patients (P=0.0134, P=0.0205). Both the GDPT and C-PET regimens significantly improved the ORR, OS, and PFS in nTFHL patients.

Conclusion

There are significant differences in the clinical manifestations, pathology, and survival outcomes among the three subtypes of nTFHLs. However, further research with a larger sample size, and involving clinical pathology and molecular genetics is needed to determine the distinctive biological characteristics of these tumors.

Clinicopathological implications of immunohistochemical expression of TBX21, CXCR3, GATA3, CCR4, and TCF1 in nodal follicular helper T-cell lymphoma and peripheral T-cell lymphoma, not otherwise specified

BACKGROUND

The classification of nodal peripheral T-cell lymphoma (PTCL) has evolved according to histology, cell-of-origin, and genetic alterations. However, the comprehensive expression pattern of follicular helper T-cell (Tfh) markers, T-cell factor-1 (TCF1), and Th1- and Th2-like molecules in nodal PTCL is unclear.

METHODS

Eighty-two cases of nodal PTCL were classified into 53 angioimmunoblastic T-cell lymphomas (AITLs)/nodal T-follicular helper cell lymphoma (nTFHL)-AI, 18 PTCLs-Tfh/nTFHL-not otherwise specified (NOS), and 11 PTCLs-NOS according to the revised 4th/5th World Health Organization classifications. Immunohistochemistry for TCF1, TBX21, CXCR3, GATA3, and CCR4 was performed.

RESULTS

TCF1 was highly expressed in up to 68% of patients with nTFHL but also in 44% of patients with PTCL-NOS (p > .05). CXCR3 expression was higher in AITLs than in non-AITLs (p = .035), whereas GATA3 expression was higher in non-AITL than in AITL (p = .007) and in PTCL-Tfh compared to AITL (p = .010). Of the cases, 70% of AITL, 44% of PTCLTfh/ nTFHL-NOS, and 36% of PTCL-NOS were subclassified as the TBX21 subtype; and 15% of AITL, 38% of PTCL-Tfh/nTFHL-NOS, and 36% of PTCL-NOS were subclassified as the GATA3 subtype. The others were an unclassified subtype. CCR4 expression was associated with poor progression-free survival (PFS) in patients with PTCL-Tfh (p < .001) and nTFHL (p = .023). The GATA3 subtype showed poor overall survival in PTCL-NOS compared to TBX21 (p = .046) and tended to be associated with poor PFS in patients with non-AITL (p = .054).

CONCLUSIONS

The TBX21 subtype was more prevalent than the GATA3 subtype in AITL. The GATA3 subtype was associated with poor prognosis in patients with non-AITL and PTCL-NOS.

Design of cyclic peptides as novel inhibitors of ICOS/ICOSL interaction

Compared to small molecules and antibodies, cyclic peptides exhibit unique biochemical and therapeutic attributes in the realm of pharmaceutical applications. The interaction between the inducible costimulator (ICOS) and its ligand (ICOSL) plays a key role in T-cell differentiation and activation. ICOS/ICOSL inhibition results in a reduction in the promotion of immunosuppressive regulatory T cells (Tregs) in both hematologic malignancies and solid tumors. Herein, we implement the computational cPEPmatch approach to design the first examples of cyclic peptides that inhibit ICOS/ICOSL interaction. The top cyclic peptide from our approach possessed an IC50 value of 1.87 ± 0.15 μM as an ICOS/ICOSL inhibitor and exhibited excellent in vitro pharmacokinetic properties as a drug candidate. Our work will lay the groundwork for future endeavors in cancer drug discovery, with the goal of developing cyclic peptides that target the ICOS/ICOSL interaction.

Pathobiology of nodal peripheral T-cell lymphomas: current understanding and future directions

Predominantly nodal is the most common clinical presentation of peripheral T- (and NK-) cell lymphomas (PTCL), which comprise three main groups of diseases: (i) systemic anaplastic large cell lymphomas (ALCL), whether positive or negative for anaplastic lymphoma kinase (ALK); (ii) follicular helper T-cell lymphomas (TFHL); and (iii) PTCL, not otherwise specified (NOS). Recent advances in the genomic and molecular characterization of PTCL, with enhanced understanding of pathobiology, have translated into significant updates in the latest 2022 classifications of lymphomas. ALK-negative ALCL is now recognized to be genetically heterogeneous, with identification of DUSP22 rearrangements in approximately 20-30% of cases, correlated with distinctive pathological and biological features. The notion of cell-of-origin as an important determinant of the classification of nodal PTCL is best exemplified by TFHL, considered as one disease or a group of related entities, sharing oncogenic pathways with frequent recurrent epigenetic mutations as well as a relationship to clonal hematopoiesis. Data are emerging to support that a similar cell-of-origin concept might be relevant to characterize meaningful subgroups within PTCL, NOS, based on cytotoxic and/or Th1 versus Th2 signatures. The small group of primary nodal Epstein-Barr virus-positive lymphomas of T- or NK-cell derivation, formerly considered PTCL, NOS, is now classified separately, due to distinctive features, and notably an aggressive course. This review summarizes current knowledge of the pathology and biology of nodal-based PTCL entities, with an emphasis on recent findings and underlying oncogenic mechanisms.

Genetic abnormalities assist in pathological diagnosis and EBV-positive cell density impact survival in Chinese angioimmunoblastic T-cell lymphoma patients

Objective

To explore the application of genetic abnormalities in the diagnosis of angioimmunoblastic T-cell lymphoma (AITL) and the reliable pathological prognostic factors.

Methods

This study included 53 AITL cases, which were reviewed for morphological patterns, immunophenotypes, presence of Hodgkin and Reed-Sternberg (HRS)-like cells, and co-occurrence of B cell proliferation. The Epstein-Barr virus (EBV)-positive cells in tissues were counted, and cases were classified into "EBV encoded RNA (EBER) high-density" group if >50/HPF. Targeted exome sequencing was performed.

Results

Mutation data can assist AITL diagnosis: 1) with considerable HRS-like cells (20 cases): RHOA mutated in 14 cases (IDH2 co-mutated in 3 cases, 4 cases with rare RHOA mutation), TET2 was mutated in 5 cases (1 case co-mutated with DNMT3A), and DNMT3A mutated in 1 case; 2) accompanied with B cell lymphoma (7 cases): RHOA mutated in 4 cases (1 case had IDH2 mutation), TET2 mutated in 2 cases and DNMT3A mutated in 1 case; 3) mimic peripheral T cell lymphoma, not otherwise specified (5 cases): RHOA mutated in 2 cases (IDH2 co-mutated in 1 case), TET2 mutated in 3 cases, and DNMT3A mutated in 1 case; 4) pattern 1 (1 case), RHOA and TET2 co-mutated. Besides RHOAG17V (30/35), rare variant included RHOAK18N, RHOAR68H, RHOAC83Y, RHOAD120G and RHOAG17del, IDH2R172 co-mutated with IDH2M397V in one case. There were recurrent mutations of FAT3, PCLO and PIEZO1 and genes of epigenetic remodeling, T-cell activation, APC and PI3K/AKT pathway. EBER high-density independently indicated adverse overall survival and progression-free survival (P=0.046 and P=0.008, Kaplan-Meier/log-rank).

Conclusions

Over half AITL cases might be confused in diagnosis for certain conditions without mutation data. Targeted exome sequencing with a comprehensive panel is crucial to detect both hot-spot and rare mutation variants for RHOA and IDH2 and other recurrent mutated genes in addition to TET2 and DNMT3A. EBER high-density independently indicated adverse survival.

First-in-class small molecule inhibitors of ICOS/ICOSL interaction as a novel class of immunomodulators

The interaction of the inducible co-stimulator (ICOS) with its ligand (ICOSL) plays key roles in T-cell differentiation and activation of T-cell to B-cell functions. The ICOS/ICOSL pathway is a validated target for T-cell lymphomas induced by the proliferation of T-follicular helper (Tfh) cells. Moreover, the inhibition of ICOS/ICOSL interaction can decrease the enhancement of immunosuppressive regulatory T cells (Tregs) in both hematologic malignancies and solid tumors. However, targeting ICOS/ICOSL interaction is currently restricted to monoclonal antibodies (mAbs) and there are no small molecules in existence that can block ICOS/ICOSL. To fill this gap, we report herein the first time-resolved fluorescence resonance energy transfer (TR-FRET) assay to evaluate the ability of small molecules to inhibit ICOS/ICOSL interaction. Implementation of the developed TR-FRET assay in high-throughput screening (HTS) of a focused chemical library resulted in the identification of AG-120 as a first-in-class inhibitor of ICOS/ICOSL interaction. We further employed docking studies and molecular dynamics (MD) simulations to identify the plausible mechanism of blocking ICOS/ICOSL complex formation by AG-120. Using the structure-activity relationship (SAR) by catalog approach, we identified AG-120-X with an IC50 value of 4.68 ± 0.47 μM in the ICOS/ICOSL TR-FRET assay. Remarkably, AG-120-X revealed a dose-dependent ability to block ICOS/ICOSL interaction in a bioluminescent cellular assay based on co-culturing Jurkat T cells expressing ICOS and CHO-K1 cells expressing ICOSL. This work will pave the way for future drug discovery efforts aiming at the development of small molecule inhibitors of ICOS/ICOSL interaction as potential therapeutics for cancer as well as other diseases.

TP53 mutations identify high-risk events for peripheral T-cell lymphoma treated with CHOP-based chemotherapy

Nodal peripheral T-cell lymphomas (PTCL), the most common PTCLs, are generally treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-based curative-intent chemotherapy. Recent molecular data have assisted in prognosticating these PTCLs, but most reports lack detailed baseline clinical characteristics and treatment courses. We retrospectively evaluated cases of PTCL treated with CHOP-based chemotherapy that had tumors sequenced by the Memorial Sloan Kettering Integrated Mutational Profiling of Actionable Cancer Targets next-generation sequencing panel to identify variables correlating with inferior survival. We identified 132 patients who met these criteria. Clinical factors correlating with an increased risk of progression (by multivariate analysis) included advanced-stage disease and bone marrow involvement. The only somatic genetic aberrancies correlating with inferior progression-free survival (PFS) were TP53 mutations and TP53/17p deletions. PFS remained inferior when stratifying by TP53 mutation status, with a median PFS of 4.5 months for PTCL with a TP53 mutation (n = 21) vs 10.5 months for PTCL without a TP53 mutation (n = 111). No TP53 aberrancy correlated with inferior overall survival (OS). Although rare (n = 9), CDKN2A-deleted PTCL correlated with inferior OS, with a median of 17.6 months vs 56.7 months for patients without CDKN2A deletions. This retrospective study suggests that patients with PTCL with TP53 mutations experience inferior PFS when treated with curative-intent chemotherapy, warranting prospective confirmation.

Follicular helper T-cell lymphomas: disease spectrum, relationship with clonal hematopoiesis, and mimics. A report of the 2022 EA4HP/SH lymphoma workshop

Follicular helper T-cell lymphomas (TFH lymphomas) were discussed in session V of the lymphoma workshop of the European Association for Haematopathology (EA4HP)/Society for Hematopathology (SH) 2022 meeting in Florence, Italy. The session focused on the morphologic spectrum of TFH lymphoma, including its three subtypes: angioimmunoblastic-type (AITL), follicular-type, and not otherwise specified (NOS). The submitted cases encompassed classic examples of TFH lymphoma and unusual cases such as those with early or indolent presentations, associated B-cell proliferations, or Hodgkin/Reed-Sternberg-like cells. The relationship between TFH lymphoma and clonal hematopoiesis was highlighted by several cases documenting divergent evolution of myeloid neoplasm and AITL from shared clonal mutations. The distinction between TFH lymphoma and peripheral T-cell lymphoma, not otherwise specified (PTCL, NOS), was stressed, and many challenging examples were presented. Various cases highlighted the difficulties of differentiating TFH lymphoma from other established types of lymphoma and reactive conditions. Cutaneous T-cell lymphoma expressing TFH markers, particularly when resulting in lymph node involvement, should be distinguished from TFH lymphomas. Additional immunophenotyping and next-generation sequencing studies were performed on various cases in this session, highlighting the importance of these technologies to our current understanding and classification of TFH lymphomas.

Distinct and overlapping features of nodal peripheral T-cell lymphomas exhibiting a follicular helper T-cell phenotype: a multicenter study emphasizing the clinicopathological significance of follicular helper T-cell marker expression

Nodal peripheral T-cell lymphoma (PTCL) is a heterogeneous category including angioimmunoblastic T-cell lymphoma (AITL), PTCL of follicular helper T-cell (Tfh) phenotype (PTCL-Tfh), and PTCL, not otherwise specified (PTCL-NOS). We explored Tfh marker profiles in nodal PTCL. Nodal PTCLs (n = 129) were reclassified into AITL (58%; 75/129), PTCL-Tfh (26%; 34/129), and PTCL-NOS (16%; 20/129). Histologically, clear cell clusters, high endothelial venules, follicular dendritic cell proliferation, EBV+ cells, and Hodgkin-Reed-Sternberg (HRS)-like cells were more common in AITL than PTCL-Tfh (HRS-like cells, P = .005; otherwise, P < .001) and PTCL-NOS (HRS-like cells, P = .028; otherwise, P < .001). PTCL-NOS had a higher Ki-67 index than AITL (P = .001) and PTCL-Tfh (P = .002). Clinically, AITL had frequent B symptoms (versus PTCL-Tfh, P = .010), while PTCL-NOS exhibited low stage (versus AITL + PTCL-Tfh, P = .036). Positive Tfh markers were greater in AITL (3.5 ± 1.1) than PTCL-Tfh (2.9 ± 0.9; P = .006) and PTCL-NOS (0.5 ± 0.5; P < .001). Tfh markers showed close correlations among them and AITL-defining histology. By clustering analysis, AITL and PTCL-NOS were relatively exclusively clustered, while PTCL-Tfh overlapped with them. Survival was not different among the PTCL entities. By Cox regression, sex and ECOG performance status (PS) independently predicted shorter progression-free survival in the whole cohort (male, P = .001, HR = 2.5; PS ≥ 2, P = .010, HR = 1.9) and in 'Tfh-lymphomas' (ie, AITL + PTCL-Tfh) (male, P = .001, HR = 2.6; PS ≥ 2, P = .016, HR = 2.1), while only PS predicted shorter overall survival (OS) in the whole cohort (P = .012, HR = 2.7) and in 'Tfh-lymphomas' (P = .001; HR = 3.2). ICOS predicted favorable OS in 'Tfh-lymphomas' (log-rank; P = .016). Despite the overlapping features, nodal PTCL entities could be characterized by Tfh markers revealing clinicopathologic implications.

Precise diagnosis and targeted therapy of nodal T-follicular helper cell lymphoma (T-FHCL)

Nodal T-follicular helper cell lymphoma (T-FHCL) derived from T-follicular helper (Tfh) cell falls into a heterogeneous category of peripheral T-cell lymphoma (PTCL). Due to the limited number of therapeutic regimens and limited first-line efficacy, T-FHCL has a poor prognosis, and there is an urgent need for effective targeted therapies. With advancements in sequencing technologies, especially single-cell sequencing and next-generation sequencing, more specific genetic aberrations characteristic of T-FHCL can be discovered, allowing for precise molecular diagnosis and specific research on novel agents. Many biomarker-targeting agents, used either alone or in combination, have been tested, and they have generally enhanced the therapeutic outcomes of T-FHCL. Histone deacetylase inhibitors achieve significant clinical benefits in the treatment of T-FHCL, especially in combination therapy. Chimeric antigen receptor T-cell (CAR-T-cell) immunotherapies, hematopoietic stem cell transplantation, and other potential agents merit further study.

Real-World Efficacy of 5-Azacytidine as Salvage Chemotherapy for Angioimmunoblastic T-cell Lymphoma

BACKGROUND

Based on specific epigenetic mutation in AITL such as TET2, DNMT3A, IDH2, and RHOA, hypomethylating agents are emerging as a promising treatment option for AITL.

METHOD

The efficacy and safety of 5-azacytidine as salvage chemotherapy were retrospectively analyzed in 15 patients with RR-AITL from 2019 to 2022.

RESULTS

During the median 6.0 months of follow-up, the overall response rate (ORR) was 40% (n = 6/15) with 2 CRs and 4 PRs. The patients who previously had received ≤2 prior chemotherapies showed higher ORR than subjects with >2 prior chemotherapies (80% vs. 20%). The 10 patients who received 5-azacitidine at the late chemotherapy lines (>2 prior chemotherapy lines) usually received less dose 5-azacitidine. And these patients discontinued treatment due to disease progression (n = 6/10, 60%) or neutropenic fever (n = 4/10, 40%). The patients who received a full dose (75 mg/m² for 7 days) of 5-azacitidine seemed to show better ORR than subjects (100 mg for 7 days) who did not receive an optimal dose (60.0% vs. 30.0%). The median progression-free survival (PFS) was 1.6 months, and the patients who previously had undergone ≤2 chemotherapies had better PFS compared with subjects who previously received >2 chemotherapies (P-value = .04).

CONCLUSION

5-azacitidine shows reasonable efficacy and manageable toxicities for patients with RR-AITL, especially those who previously received ≤2 chemotherapy lines.

Epigenetic Aberrations and Targets in Peripheral T-Cell Lymphoma

Peripheral T cell lymphomas (PTCL) comprise a diverse group of aggressive T-cell and NK-cell lymphomas with many subtypes sharing same treatment algorithms despite having different pathobiology and responses to treatment. The molecular advances made in discovery of genetic mutations that disrupt epigenetic modulation in some subtypes of PTCL such as angioimmunoblastic T cell lymphoma and PTCL-not otherwise specified (NOS) may explain the poor outcomes and unsatisfactory responses to frontline line CHOP and CHOP-like therapy seen in this group of lymphomas. In this article, we address the main genetic mutations such as IDH2, TET2 and DNMT3A seen in PTCL and that disrupt the epigenetic modulation pathways, focusing on acetylation, deacetylation and methylation. Since therapeutic agents that target the disrupted epigenetic modulation pathways in PTCL may change treatment landscape in the near future, we will highlight the ones approved for treatment of refractory and/or relapsed PTCL and also the pivotal regimens being evaluated in clinical trials for treatment of frontline and refractory relapsed disease. We stress the importance of determining whether there is an association between the discussed genetic mutations and responses to the highlighted therapeutic agents such that treatments could be better tailored in patients with this kind of lymphoma with unmet needs.

Comprehensive comparison of international prognostic indexes for follicular helper T-cell lymphoma

In 2016, World Health Organization classification of lymphoid neoplasms separated firmly-follicular helper (Tfh) cell origin lymphomas from peripheral T-cell lymphoma-not specified (PTCL-NOS) based on their unique immunogenic characteristics. Generally, Tfh cell origin lymphoma, which has an approximately 25% incidence, is classified into three categories: angioimmunoblastic T-cell lymphoma (AITL), follicular peripheral T-cell lymphoma (F-PTCL), and nodal peripheral T-cell lymphoma with a T-follicular helper phenotype (nodal PTCL with Tfh cell phenotype). Their prognosis has been estimated using four traditional prognostic tools for T-cell lymphoid malignancies: the international prognostic index (IPI), the prognostic index for peripheral T-cell lymphoma unspecified (PIT), the modified PIT (mPIT) and the international T-cell lymphoma project index. In addition, the AITL score that reflects AITL characteristics well has been introduced recently. However, there are no clear guidelines for evaluating the prognosis of Tfh cell lymphoma. Thus, we performed a comparative analysis to determine which of these five indexes is most suitable for Tfh cell lymphoma. We evaluated the accuracy of classification according to risk score and predicted survival rate. Based on review by lymphoma pathology experts, we enrolled 198 patients diagnosed with Tfh cell lymphoma in this retrospective study. AITL was the most common subtype (n = 168), followed by F-PTCL (n = 21) and nodal PTCL with Tfh cell phenotype (n = 9). The median progression-free survival and overall survival with front-line treatment was 0.8 years (95% confidence interval [CI], 0.6-1.1 years) and 2.9 years (95% CI, 1.6-4.2 years), respectively. The AITL score showed better differentiation than other scoring systems in terms of classification according to risk score. However, for predicting PFS (concordance-index [C-index], IPI vs. PIT vs. modified PIT vs. international T-cell lymphoma project index vs. AITL score; 0.617 vs. 0.605 vs. 0.576 vs. 0.591 vs. 0.592) and OS (C-index, IPI vs. PIT vs. modified PIT vs. international T-cell lymphoma project index vs. AITL score; 0.663 vs. 0.651 vs. 0.612 vs. 0.672 vs. 0.583), the IPI, and the international T-cell lymphoma project index showed better performance. In conclusion, there are unmet needs to develop a prognostic index for Tfh cell lymphoma because its characteristics differ from PTCL-NOS. Although the AITL score reflects Tfh cell-origin lymphoma characteristics well and clearly shows their power of classification according to risk score, there are concerns about accurate prediction of survival outcomes. Therefore, it seems too early to settle on a single scoring system in Tfh cell origin lymphoma. In the future, along with classification, a more effective tool for survival prediction needs to be developed that reflects the specific characteristics of T-cell lymphoma.

Diagnostic Impact of Next-Generation Sequencing Panels for Lymphoproliferative Neoplasms on Small-Volume Biopsies

OBJECTIVES

We investigated the feasibility and utility of next-generation sequencing (NGS)-based targeted somatic mutation panels and IG/TR gene rearrangement assays in the diagnosis of lymphoproliferative disorders (LPDs) in small-volume biopsies.

MATERIALS

We performed a retrospective, single-institution review of all NGS assays requested over a 3-year period by hematopathologists for diagnostic purposes on small-volume biopsies.

RESULTS

We identified 59 small-volume biopsies. The TR assay was most commonly requested (42 [71%]), followed by the somatic mutation panel (32 [54%]) and IG assay (26 [44%]). NGS studies were associated with a change in the diagnostic line in about half of cases (28 [47%]) and in a change in the likelihood of a diagnosis in a further 16 cases (27%); there was no diagnostic impact of NGS testing in 15 cases (25%).

CONCLUSIONS

Implementation of NGS panel somatic mutation or IG/TR gene rearrangement assays on small-volume biopsies contributes to the diagnosis of LPDs in the majority of select cases for diagnostic purposes. The molecular diagnosis is considered in the context of the clinical, histologic, and immunophenotypic findings and does not by itself lead to a definitive diagnosis in small-volume biopsies.

Chimeric Antigen Receptor Based Cellular Therapy for Treatment Of T-Cell Malignancies

T-cell malignancies can be divided into precursor (T-acute lymphoblastic leukemia/lymphoblastic lymphoma, T-ALL/LBL) and mature T-cell neoplasms, which are comprised of 28 different entities. Most of these malignancies are aggressive with rather poor prognosis. Prognosis of relapsed/refractory (R/R) disease is especially dismal, with an expected survival only several months after progression. Targeted therapies, such as antiCD30 immunotoxin brentuximab vedotin, antiCD38 antibody daratumumab, and anti-CCR4 antibody mogamulizumab are effective only in subsets of patients with T-cell neoplasms. T-cells equipped with chimeric antigen receptor (CAR-Ts) are routinely used for treatment of R/R B-cell malignancies, however, there are specific obstacles for their use in T-cell leukemias and lymphomas which are fratricide killing, risk of transfection of malignant cells, and T-cell aplasia. The solution for these problems relies on target antigen selection, CRISPR/Cas9 or TALEN gene editing, posttranslational regulation of CAR-T surface antigen expression, and safety switches. Structural chromosomal changes and global changes in gene expression were observed with gene-edited products. We identified 49 studies of CAR-based therapies registered on www.clinicaltrials.gov. Most of them target CD30 or CD7 antigen. Results are available only for a minority of these studies. In general, clinical responses are above 50% but reported follow-up is very short. Specific toxicities of CAR-based therapies, namely cytokine release syndrome (CRS), seem to be connected with the antigen of interest and source of cells for manufacturing. CRS is more frequent in antiCD7 CAR-T cells than in antiCD30 cells, but it is mild in most patients. More severe CRS was observed after gene-edited allogeneic CAR-T cells. Immune effector cell associated neurotoxicity (ICANS) was mild and infrequent. Graft-versus-host disease (GvHD) after allogeneic CAR-T cells from previous hematopoietic stem cell donor was also observed. Most frequent toxicities, similarly to antiCD19 CAR-T cells, are cytopenias. CAR-based cellular therapy seems feasible and effective for T-cell malignancies, however, the optimal design of CAR-based products is still unknown and long-term follow-up is needed for evaluation of their true potential.

Human Germinal Center-associated Lymphoma (HGAL) Is a Reliable Marker of Normal and Neoplastic Follicular Helper T Cells Including Angioimmunoblastic T-Cell Lymphoma

The diagnosis of angioimmunoblastic T-cell lymphoma (AITL) is complex and requires the demonstration of a T-follicular helper (TFH) phenotype. Immunophenotypic markers that detect the TFH phenotype are highly variable, thereby necessitating the use of 3 to 5 TFH markers to substantiate a TFH phenotype. We tested the utility of germinal center markers human germinal center-associated lymphoma (HGAL) and LIM-domain only 2 (LMO2) in detecting a TFH phenotype. We compared their staining to that of 6 TFH markers in current use, PD-1, ICOS, CXCL13, SAP, CD10, and BCL6, in a cohort of 23 AITL. Our results show that although both markers can detect a TFH phenotype, HGAL was superior to LMO2 in the percent of cells stained and the intensity of staining, 2 variables used to generate H-scores. Using H-scores as the metric, HGAL was most comparable to BCL6 among the currently used TFH markers and was more sensitive than CXCL13, SAP, CD10, and LMO2. PD-1 and ICOS emerged as the most robust of the 8 markers tested in this study in detecting a TFH phenotype. We conclude that HGAL is a reliable marker of TFH cells and can aid in the diagnosis of lymphomas of TFH derivation, particularly in the recognition of early patterns of AITL.

Peripheral T-cell lymphoma: Molecular profiling recognizes subclasses and identifies prognostic markers

Gene expression and mutational analysis confirm the differences among the 3 peripheral TCL subclasses: AITL, PTCL-NOS, and PTCL-TFH.

The expression of a gene set, including B-cell genes, is an IPI-independent prognostic factor for AITL cases.

Peripheral T-cell lymphoma (PTCL) is a clinically aggressive disease, with a poor response to therapy and a low overall survival rate of approximately 30% after 5 years. We have analyzed a series of 105 cases with a diagnosis of PTCL using a customized NanoString platform (NanoString Technologies, Seattle, WA) that includes 208 genes associated with T-cell differentiation, oncogenes and tumor suppressor genes, deregulated pathways, and stromal cell subpopulations. A comparative analysis of the various histological types of PTCL (angioimmunoblastic T-cell lymphoma [AITL]; PTCL with T follicular helper [TFH] phenotype; PTCL not otherwise specified [NOS]) showed that specific sets of genes were associated with each of the diagnoses. These included TFH markers, cytotoxic markers, and genes whose expression was a surrogate for specific cellular subpopulations, including follicular dendritic cells, mast cells, and genes belonging to precise survival (NF-κB) and other pathways. Furthermore, the mutational profile was analyzed using a custom panel that targeted 62 genes in 76 cases distributed in AITL, PTCL-TFH, and PTCL-NOS. The main differences among the 3 nodal PTCL classes involved the RHOA^G17V mutations (P < .0001), which were approximately twice as frequent in AITL (34.09%) as in PTCL-TFH (16.66%) cases but were not detected in PTCL-NOS. A multivariate analysis identified gene sets that allowed the series of cases to be stratified into different risk groups. This study supports and validates the current division of PTCL into these 3 categories, identifies sets of markers that can be used for a more precise diagnosis, and recognizes the expression of B-cell genes as an IPI-independent prognostic factor for AITL.