Survival following salvage therapy for primary refractory peripheral T-cell lymphomas (PTCL)

Pooled analysis of pralatrexate single-agent studies in patients with relapsed/refractory peripheral T-cell lymphoma

ABSTRACT

Patients with relapsed or refractory (R/R) mature natural killer cell and T-cell lymphoma have limited treatment options. To evaluate pralatrexate's performance and factors influencing its safety and efficacy in R/R peripheral T-cell lymphoma (PTCL), we performed a pooled analysis of data from 4 similarly designed, regulatory-mandated prospective clinical trials. Of 221 patients (median age, 59 years; 67.0% male) in the study population, 48.9% had PTCL not otherwise specified (PTCL-NOS), 21.3% angioimmunoblastic T-cell lymphoma, and 11.8% ALK-negative anaplastic large cell lymphoma (ALCL). Patients received pralatrexate for a median of 2.56 months (range, 0.03-24.18) and had a 40.7% objective response rate with a median duration of response of 9.1 months, progression-free survival 4.6 months, and overall survival 16.3 months. The most common treatment-related all-grade adverse events were stomatitis, thrombocytopenia, white blood cell count decrease, pyrexia, and vomiting. Subgroup exploratory analyses suggest improved efficacy with 1 prior line of chemotherapy vs 2 or ≥4 prior lines; PTCL-NOS or ALCL vs transformed mycosis fungoides; chemotherapy and transplant before pralatrexate vs chemotherapy alone or chemotherapy with other nontransplant treatments. In conclusion, these pooled analysis results further support using pralatrexate in patients with R/R PTCL. Prospective studies are needed to confirm the findings of subgroups analyses.

Romidepsin Plus Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone Versus Cyclophosphamide, Doxorubicin, Vincristine, and Prednisone in Patients With Previously Untreated Peripheral T-Cell Lymphoma: Final Analysis of the Ro-CHOP Trial

Clinical trials frequently include multiple end points that mature at different times. The initial report, typically based on the primary end point, may be published when key planned co-primary or secondary analyses are not yet available. Clinical Trial Updates provide an opportunity to disseminate additional results from studies, published in JCO or elsewhere, for which the primary end point has already been reported.The primary analysis of the Ro-CHOP phase III randomized controlled trial (ClinicalTrials.gov identifier: NCT01796002) established that romidepsin (Ro) plus cyclophosphamide, doxorubicin, vincristine, prednisone (CHOP) did not yield an increased efficacy compared with CHOP alone as first-line treatment of peripheral T-cell lymphoma. We report the planned final analysis 5 years after the last patient enrolled. With a median follow-up of 6 years, median progression-free survival (PFS) was 12.0 months compared with 10.2 months (hazard ratio [HR], 0.79 [95% CI, 0.62 to 1.005]; P = .054), while median overall survival was 62.2 months (35.7-86.6 months) and 43.8 months (30.1-70.2 months; HR, 0.88 [95% CI, 0.68 to 1.14]; P = .324) in the Ro-CHOP and CHOP arms, respectively. In an exploratory analysis, the median PFS in the centrally reviewed follicular helper T-cell lymphoma subgroup was significantly longer in the Ro-CHOP arm (19.5 v 10.6 months, HR, 0.703 [95% CI, 0.502 to 0.985]; P = .039). Second-line treatments were given to 251 patients with a median PFS2 and OS2 after relapse or progression of 3.3 months and 11.5 months, respectively. Within the limits of highly heterogeneous second-line treatments, no specific regimen seemed to provide superior disease control. However, a potential benefit was observed with brentuximab vedotin in association with chemotherapy even after excluding anaplastic large-cell lymphoma subtype or after adjusting for histology and international prognostic index in a multivariate model (HR for PFS, 0.431 [95% CI, 0.238 to 0.779]; P = .005).

Hematopoietic stem cell transplantation for pediatric patients with non-anaplastic peripheral T-cell lymphoma. An EBMT pediatric diseases working party study

Peripheral T-cell lymphomas (PTCL) other than anaplastic large-cell lymphoma are rare in children, and the role of hematopoietic stem cell transplantation (HSCT) has not been clarified yet. In a retrospective analysis of registry-data of the European Society for Blood and Marrow Transplantation we analyzed 55 patients aged < 18 years who received allogeneic (N = 46) or autologous (N = 9) HSCT for PTCL. Median age at HSCT was 13.9 years; 33 patients (60%) were in first remission, and 6 (19%) in progression at HSCT. Conditioning was myeloablative in 87% of the allogeneic HSCTs and in 27 (58.7%) based on total body irradiation. After allogeneic HSCT the 5-year overall- and progression-free survival was 58.9% (95% CI 42.7-71.9) and 52.6% (95% CI 36.8-66.1), respectively. 5-year relapse incidence was 27.6% (95% CI 15.1-41.6), the non-relapse mortality rate was 19.8% (95% CI 9.7-32.6). Five of the six patients with progression at HSCT died. Seven of nine patients after autologous HSCT were alive and disease-free at last follow-up. Our data suggest a role of allogeneic HSCT in consolidation-treatment of patients with high-risk disease, who reach at least partial remission after primary- or relapse-therapy, whereas patients with therapy-refractory or progressive disease prior to transplantation do not profit from HSCT.

Autologous stem cell transplant for refractory and relapsed peripheral T-cell lymphoma: a retrospective study in China

Objective To evaluate the efficacy and prognostic factors of high-dose therapy/autologous stem cell transplantation (HDT/ASCT) in treating refractory and relapsed peripheral T-cell lymphoma (R/R PTCL). Methods We included medical records from 48 R/R PTCL patients treated with HDT/ASCT at the Beijing Cancer Hospital from January 2003 to December 2021, and these patients were followed up. Results We followed up with patients for a median of 71.0 months (interquartile range 48.8-124.4 months). The progression-free survival (PFS) at five years was 43.4%, and the five-year overall survival (OS) was 54.7. The five-year PFS and subgroups were as follows: 14 patients with anaplastic large-cell lymphoma (57.1%, 62.9%), 14 patients with NK/T-cell lymphoma (NKTCL) (28.6%, 28.6%), nine with angioimmunoblastic T-cell lymphoma (44.4%, 51.9%), and 11 with PTCL not otherwise specified (41.6%, 80.8%). Univariate analysis revealed that females had a better PFS than males (hazard ratio [HR] = 0.301, 95% confidence interval [CI] 0.091-0.996, P = 0.049); the NKTCL type had worse OS than the non-NKTCL type (HR = 0.292, 95% CI 0.122-0.698, P = 0.006); the patients with the relapsed disease did better than those with refractory disease (HR for PFS: 0.161, 95% CI 0.072-0.357, P < 0.001; HR for OS: 0.171, 95% CI 0.066-0.444, P < 0.001). The PIT score was significantly better for T-cell lymphoma with score = 0 than for score ≥ 1 group (HR for PFS: 0.261, 95% CI 0.109-0.625, P = 0.003; HR for OS: 0.305, 95% CI 0.111-0.842, P = 0.022). The pre-transplantation disease status also influences survival. Patients who achieved complete response (CR) did better (HR for PFS: 0.104, 95% CI 0.044-0.247, P < 0.001; HR for OS: 0.139, 95% CI 0.050-0.383, P < 0.001). Pre-transplantation status was an independent influencing factor associated with PFS and OS (better survival in those achieving CR) (HR for PFS: 0.126, 95% CI 0.030-0.530, P = 0.005; HR for OS: 0.154, 95% CI 0.040-0.603, P = 0.007); the pathological classification independently influenced OS (better in the those with non-NKTCL) (HR = 0.210, 95% CI 0.081-0.549, P = 0.001). CR, with a PIT score of 0 (n = 17), was associated with more prolonged PFS. None of the 48 patients experienced HDT/ASCT-related deaths. Conclusion HDT/ASCT as a salvage therapy for R/R PTCL patients can partially improve outcomes with a favorable safety profile. Prospective, randomized, and controlled studies are necessary to validate the value of HDT/ASCT for patients with diverse pathological subtypes and pre-transplantation states.

Darinaparsin in patients with relapsed or refractory peripheral T-cell lymphoma: results of an Asian phase 2 study

Darinaparsin is a novel organic arsenical compound of dimethylated arsenic conjugated to glutathione, with antitumor activity and a mechanism of action markedly different from other available agents. This phase 2, nonrandomized, single-arm, open-label study evaluated the efficacy and safety of intravenous darinaparsin (300 mg/m2 over 1 hour, once daily for 5 consecutive days, per 21-day cycle) and its pharmacokinetics at multiple doses in 65 Asian patients with relapsed or refractory peripheral T-cell lymphoma (PTCL). The primary end point was the overall response rate (ORR). The ORR based on central assessment was 19.3% (90% confidence interval, 11.2-29.9), which was significantly higher than the predefined threshold of 10% (P = .024). The ORR was 16.2% in patients with PTCL-not otherwise specified and 29.4% in patients with angioimmunoblastic T-cell lymphoma. Tumor size decreased in 62.3% of patients. Treatment-emergent adverse events (TEAEs) were observed in 98.5% of patients. Grade ≥3 TEAEs with an incidence rate of ≥5% included anemia (15.4%), thrombocytopenia (13.8%), neutropenia (12.3%), leukopenia (9.2%), lymphopenia (9.2%), and hypertension (6.2%). Darinaparsin is effective and well tolerated, with TEAEs that were clinically acceptable and manageable with symptomatic treatment and dose reductions. This trial was registered at www.clinicaltrials.gov as #NCT02653976.

Autologous, allogeneic hematopoietic cell transplantation and CAR-T/NK therapy: what is their real importance in PTCL?

Peripheral T cell lymphoma (PTCL) is a rare and aggressive type of non-Hodgkin's lymphoma that affects mature T cells. This type of cancer is characterized by the abnormal growth of T cells, which can accumulate in the lymph nodes, spleen, bone marrow, and other organs, leading to a variety of symptoms. PTCLs are often difficult to diagnose and treat, and they have a poorer prognosis than other types of lymphoma. However, recent advancements in treatment options, such as targeted therapies have shown promise in improving outcomes for patients with PTCL. Here, we discuss the use of autologous and allogeneic hematopoietic cell transplantation (HCT) as a treatment strategy for patients with PTCL, as well as the recent treatment approaches based on advanced cellular therapy. The current evidence for the use of HCT in PTCL is mainly derived from registry data, retrospective studies, and expert opinion, as randomized trials are limited due to the low incidence and histological heterogeneity of PTCL subtypes.

PTCL, NOS: An update on classification, risk-stratification, and treatment

The peripheral T-cell lymphomas (PTCL) are relatively rare, heterogeneous, and therapeutically challenging. While significant therapeutic gains and improved understanding of disease pathogenesis have been realized for selected PTCL subtypes, the most common PTCL in North America remains "not otherwise specified (NOS)" and is an unmet need. However, improved understanding of the genetic landscape and ontogeny for the PTCL subtypes currently classified as PTCL, NOS have been realized, and have significant therapeutic implications, which will be reviewed here.

Targeting Lymphoma-associated Macrophage Expansion via CSF1R/JAK Inhibition is a Therapeutic Vulnerability in Peripheral T-cell Lymphomas

The reciprocal relationship between malignant T cells and lymphoma-associated macrophages (LAM) within the tumor microenvironment (TME) is unique, as LAMs are well poised to provide ligands for antigen, costimulatory, and cytokine receptors that promote T-cell lymphoma growth. Conversely, malignant T cells promote the functional polarization and homeostatic survival of LAM. Therefore, we sought to determine the extent to which LAMs are a therapeutic vulnerability in these lymphomas, and to identify effective therapeutic strategies for their depletion. We utilized complementary genetically engineered mouse models and primary peripheral T-cell lymphoma (PTCL) specimens to quantify LAM expansion and proliferation. A high-throughput screen was performed to identify targeted agents that effectively deplete LAM within the context of PTCL. We observed that LAMs are dominant constituents of the TME in PTCL. Furthermore, their dominance was explained, at least in part, by their proliferation and expansion in response to PTCL-derived cytokines. Importantly, LAMs are a true dependency in these lymphomas, as their depletion significantly impaired PTCL progression. These findings were extrapolated to a large cohort of human PTCL specimens where LAM proliferation was observed. A high-throughput screen demonstrated that PTCL-derived cytokines led to relative resistance to CSF1R selective inhibitors, and culminated in the identification of dual CSF1R/JAK inhibition as a novel therapeutic strategy to deplete LAM in these aggressive lymphomas. Malignant T cells promote the expansion and proliferation of LAM, which are a bone fide dependency in these lymphomas, and are effectively depleted with a dual CSF1R/JAK inhibitor.

Significance

LAMs are a therapeutic vulnerability, as their depletion impairs T-cell lymphoma disease progression. Pacritinib, a dual CSF1R/JAK inhibitor, effectively impaired LAM viability and expansion, prolonged survival in preclinical T-cell lymphoma models, and is currently being investigated as a novel therapeutic approach in these lymphomas.

Comparison of chidamide-contained treatment modalities versus chemotherapy in the second-line treatment for relapsed or refractory peripheral T-cell lymphoma

Peripheral T-cell lymphoma (PTCL) is characterized by an aggressive clinical behavior. Chidamide has been approved for the treatment of relapsed/refractory (R/R) PTCL in China. We compared the efficacy of chidamide-contained regimens with chemotherapy (ChT) in R/R PTCL. Based on the second-line treatments, patients were divided into three groups, including ChT, ChT combined with chidamide (chidamide + ChT) and chidamide combined with or without other targeted agents (targeted therapy) group. Chidamide + ChT group had a better progression-free survival (PFS) compared with targeted therapy group (p = 0.013), and showed a trend towards superior PFS compared with ChT group (p = 0.079). Among patients with high second-line International Prognostic Index (IPI) (3-5), chidamide+ChT group had a longer PFS than ChT group(p = 0.018), and PFS in targeted therapy group was not inferior to that in chidamide+ChT group (p = 0.200). Among patients younger than 60 years, chidamide+ChT group demonstrated a PFS benefit over targeted therapy group (p = 0.010). Among CD30-negative patients, PFS was superior in the chidamide+ChT group compared with ChT group (p < 0.001). Conversely, results observed above were absent in patients with low second-line IPI or patients older than 60 years or CD30-positive patients. Overall, the combination of chidamide and ChT may be an effective treatment strategy for R/R PTCL.

A novel lncRNA TCLlnc1 promotes peripheral T cell lymphoma progression through acting as a modular scaffold of HNRNPD and YBX1 complexes

Long noncoding RNAs (lncRNAs) play an essential role in tumor progression. Few researches focused on the clinical and biological relevance of lncRNAs in peripheral T cell lymphoma (PTCL). In this research, a novel lncRNA (ENST00000503502) was identified overexpressed in the main subtypes of PTCL, and designated as T cell lymphoma-associated lncRNA1 (TCLlnc1). Serum TCLlnc1 was associated with extranodal involvement, high-risk International Prognostic Index, and poor prognosis of the patients. Both in vitro and in vivo, overexpression of TCLlnc1 promoted T-lymphoma cell proliferation and migration, both of which were counteracted by the knockdown of TCLlnc1 using small interfering RNAs. As the mechanism of action, TCLlnc1 directly interacted with transcription activator heterogeneous nuclear ribonucleoprotein D (HNRNPD) and Y-box binding protein-1 (YBX1) by acting as a modular scaffold. TCLlnc1/HNRNPD/YBX1 complex upregulated transcription of TGFB2 and TGFBR1 genes, activated the tumor growth factor-β signaling pathway, resulting in lymphoma progression, and might be a potential target in PTCL.

Hematopoietic Cell Transplantation and Adoptive Cell Therapy in Peripheral T Cell Lymphoma

PURPOSE OF REVIEW

Peripheral T cell lymphomas (PTCLs) are a heterogeneous group of diseases and represent approximately 10-15% of all non-Hodgkin lymphomas. Multiagent chemotherapy with a CHOP (cyclophosphamide, adriamycin, vincristine, prednisone)-like regimen is the current standard of care in the frontline setting, but outcomes for PTCL patients generally remain poor. Strategies used to improve survival and reduce the risk of relapse in PTCL patients include autologous hematopoietic cell transplant (autoHCT) and allogeneic HCT (alloHCT). Due to the relative rarity of these diseases, the evidence supporting the use of autoHCT and alloHCT is based on retrospective and single-arm prospective studies. Novel targeted therapies are now being incorporated into the treatment of PTCL, and they may play important roles in improving upon current standards of care. Herein, we summarize the evidence supporting HCT for the treatment of the most common PTCL histologic subtypes and highlight novel treatment strategies aimed at improving outcomes for these patients, including cutting-edge approaches using chimeric antigen receptor T cells (CAR-T).

RECENT FINDINGS

Given recent improvements in OS and PFS in CD30+ PTCL using the drug-antibody conjugate brentuximab vedotin (BV), new questions arise regarding the impact of BV on consolidative autoHCT, and its role as a maintenance therapy. Multiple histone deacetylase inhibitors (HDACis) have been approved for the treatment of relapsed/refractory PTCL, and these agents are being incorporated into HCT approaches, both in the frontline and maintenance settings. Early data incorporating these agents into novel conditioning regimens have been reported, and emerging evidence from recent trials suggests that CART cell therapies may prove effective in relapsed/refractory PTCL. The recommended treatment strategy in non-ALK+ PTCL remains induction with a CHOP-like regimen followed by consolidative autoHCT in first remission. In the relapsed/refractory setting, salvage chemotherapy followed by HCT (autoHCT or alloHCT depending on histologic subtype and HCT history) offers the only potential for cure or long-term remission. Ample room for improvement remains in the treatment of patients with PTCL, and novel treatment strategies incorporating targeted agents and CAR-T therapy may help to address the unmet needs of this patient population.

Autologous hematopoietic stem cell transplantation with inadequate stem cell dose in patients with non-Hodgkin lymphoma

Little is known regarding the outcome of lymphoma patients undergoing autologous hematopoietic stem cell transplantation (AHSCT) using inadequate hematopoietic stem cell (HSC) doses. Fifty-six patients were enrolled in the study, and the cohort was subdivided into two groups according to the infusion dose: < 1 × 10⁶/kg (poor HSC group) and 1-2 × 10⁶/kg (unfavorable HSC group). Compared with the unfavorable group, the poor HSC group had a longer median time to neutrophil (13 vs. 11 days, p = .007) and platelet engraftment (17 vs. 13 days, p = .024). CD34+ cell infusion dose of < 1 × 10⁶/kg was the only risk factor for neutrophil and platelet engraftment. The expected 3-year progression-free survival and overall survival rates for the whole cohort were 53% and 66%, and no statistical difference was observed between two groups. In conclusion, inadequate HSC infusion dose did not negatively impact AHSCT patient survival but significantly prolonged the time to hematopoietic engraftment.

Evaluation of prognosis following early disease progression in peripheral T-cell lymphoma

Recently, progression of disease within 24 months (POD24) has been demonstrated as a strong prognostic indicator in various types of malignant lymphoma. Peripheral T-cell lymphoma (PTCL) has an aggressive course and poor clinical outcomes. In this multicenter retrospective study, 111 consecutively registered patients with newly diagnosed PTCL were analyzed. Of these patients, 72 (64.9%) experienced POD24 (POD24 group), and the other 39 patients (35.1%) were analyzed as the no POD24 group. In the POD24 group, overall survival (OS) was significantly inferior to all patients, and in the no POD24 group, subsequent OS was significantly superior to the POD24 group, although the clinical characteristics between the POD24 group and no POD24 group were not significantly different. Twenty-three patients (20.7%) showed primary refractory disease to first-line therapy, and the prognosis was poor. The International Prognostic Index score and POD24 were identified as independent predictors in multivariate analysis for OS in all patients, and only performance status was an independent prognostic factor for OS in the POD24 group in multivariate analysis. In conclusion, the clinical significance of assessing POD24 in PTCL and the poor prognosis in patients with early disease progression were demonstrated.

The impact of allogeneic hematopoietic cell transplantation on the mortality of poor-risk non-Hodgkin lymphoma: an intent-to-transplant analysis

Purpose of this single-centre retrospective study was to assess the outcome of allogeneic hematopoietic cell transplantation (alloHCT) for relapsed/refractory (r/r) non-Hodgkin lymphoma (NHL) by intent-to-transplant (ITT). Included were all consecutive patients with diffuse large B-cell lymphoma (DLBCL), follicular lymphoma (FL), mantle cell lymphoma (MCL), and peripheral T-cell lymphoma (PTCL) for whom a donor search was performed between 2004 and 2018. Primary endpoint was overall survival (OS) measured from search initiation. A donor search was initiated for 189 patients (DLBCL 61, FL 32, MCL 43, and PTCL 53), with 76% of the patients having active disease. OS at 5 years after search initiation for DLBCL, FL, MCL, and PTCL was 26%, 44%, 52%, and 50%, respectively. AlloHCT was performed in 137 patients (72%; DLBCL 64%). Main reason for not undergoing alloHCT was disease progression, whereas donor unavailability accounted for only 4% of pretransplantation failures. These results suggest that survival of patients with r/r NHL entering the alloHCT route may be overestimated by a factor of 1.2-1.4 if based on actually transplanted patients only. This effect should be taken into account when using alloHCT as benchmark for new therapeutic approaches for the treatment of poor-risk NHL.

Allogeneic stem cell transplantation for peripheral T cell lymphomas: a retrospective study in 285 patients from the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire (SFGM-TC)

BACKGROUND

Peripheral T cell lymphomas form a heterogeneous group with a usually dismal prognostic. The place of allogeneic stem cell transplantation to treat PTCL is debated.

METHODS

We retrospectively analyzed the overall survival (OS), event-free survival (EFS), relapse, and transplant-related mortality (TRM) and associated variables in 285 adults with non-primary cutaneous PTCL (PCTL-NOS (39%), angioimmunoblastic T cell lymphomas (29%), anaplastic T cell lymphomas (15%), and other subtypes (17%)), who received alloSCT in 34 centers between 2006 and 2014.

RESULTS

AlloSCT was given as part of front-line therapy (n = 138) to 93 patients in first complete response (CR) and 45 in first partial response (PR), and of salvage therapy (n = 147) to 116 patients for second or more CR/PR and 31 for progressive disease. Reduced-intensity conditioning (RIC) was given to 172 patients (62%), while 107 (38%) received myeloablative conditioning (MAC). The median follow-up was 72.4 months. The 2- and 4-year OS were 65% and 59%, respectively, and the cumulative incidence of relapse was 18% after 1 year and 19% after 2 years. TRM was 21% at 1 year, 24% after 2 years, and 28% after 4 years. In multivariate analysis, grade III-IV acute GvHD (HR = 2.57, 95% CI 1.53-4.31; p = 0.00036), low Karnofsky score < 80% (HR = 5.14, 95% CI 2.02-13.06; p = 0.00058), and progressive disease status before transplant (HR = 2.21, 95% CI 1.25-3.89; p = 0.0062) were significantly associated with a reduced OS.

CONCLUSIONS

The data demonstrate in the largest retrospective cohort of non-cutaneous PTCL so far reported that alloSCT after RIC or MAC is an effective strategy, even in chemoresistant patients.

The new biology of PTCL-NOS and AITL: current status and future clinical impact

Peripheral T-cell lymphomas (PTCL) comprise a heterogeneous group of aggressive lymphoproliferative disorders almost all of which are associated with poor clinical outcomes. Angioimmunoblastic T-cell lymphoma (AITL) and some peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS) have similarities to normal CD4⁺ T-cell subsets in their gene expression profiles. A cell of origin model is, therefore, emerging and is likely to be refined in the future. Follicular helper (Tfh) T cells are now established as the cell of origin of AITL and about 20% of PTCL-NOS. Sequencing studies have identified recurrent genetic alterations in epigenetic modifiers, T-cell receptor signalling pathway intermediates or RHOA, most commonly a specific mutation leading to RHOA G17V. While PTCL-NOS remains a diagnosis of exclusion, advances in genomics have identified subgroups expressing transcription factors TBX 21 (Th1-like origin) and GATA3 (Th2-like origin). These findings suggest new biomarkers and new therapeutic avenues including the hypomethylating agent azacytidine, or inhibitors of proximal T-cell receptor (TCR) signalling and potentially certain monoclonal antibodies. The advances over the past few years, therefore, prompt stratified medicine approaches to test biologically based treatments and determine the clinical utility of the new disease classifications.

Colony-Stimulating Factor 1 Receptor (CSF1R) Activates AKT/mTOR Signaling and Promotes T-Cell Lymphoma Viability

PURPOSE

Peripheral T-cell lymphomas are clinically aggressive and usually fatal, as few complete or durable remissions are achieved with currently available therapies. Recent evidence supports a critical role for lymphoma-associated macrophages during T-cell lymphoma progression, but the specific signals involved in the cross-talk between malignant T cells and their microenvironment are poorly understood. Colony-stimulator factor 1 receptor (CSF1R, CD115) is required for the homeostatic survival of tissue-resident macrophages. Interestingly, its aberrant expression has been reported in a subset of tumors. In this article, we evaluated its expression and oncogenic role in T-cell lymphomas.

EXPERIMENTAL DESIGN

Loss-of-function studies, including pharmacologic inhibition with a clinically available tyrosine kinase inhibitor, pexidartinib, were performed in multiple in vitro and in vivo models. In addition, proteomic and genomic screenings were performed to discover signaling pathways that are activated downstream of CSF1R signaling.

RESULTS

We observed that CSF1R is aberrantly expressed in many T-cell lymphomas, including a significant number of peripheral and cutaneous T-cell lymphomas. Colony-stimulating factor 1 (CSF1), in an autocrine or paracrine-dependent manner, leads to CSF1R autophosphorylation and activation in malignant T cells. Furthermore, CSF1R signaling was associated with significant changes in gene expression and in the phosphoproteome, implicating PI3K/AKT/mTOR in CSF1R-mediated T-cell lymphoma growth. We also demonstrated that inhibition of CSF1R in vivo and in vitro models is associated with decreased T-cell lymphoma growth.

CONCLUSIONS

Collectively, these findings implicate CSF1R in T-cell lymphomagenesis and have significant therapeutic implications.

GATA-3 in T-cell lymphoproliferative disorders

GATA-3 regulates the differentiation, proliferation, survival, and function of peripheral T cells and their thymic progenitors. Recent findings, reviewed here, not only implicate GATA-3 in the pathogenesis of molecularly, genetically, and clinically distinct T-cell lymphoproliferative disorders, but also have significant diagnostic, prognostic, and therapeutic implications.

Allogeneic stem cell transplantation for patients with relapsed or refractory T-cell lymphoma: efficacy of lymphoma-directed conditioning against advanced disease

Salvage chemotherapy induces disease remissions in patients with relapsed or refractory (r/r) T-cell lymphomas, but fails to provide lasting tumor control. We analyzed the outcome after peripheral blood stem and bone marrow transplantation (PBSCT, n = 80; BMT, n = 4) from matched related (MRD, n = 22) or matched and unmatched unrelated donors (MUD and MMD, n = 53 and n = 9, respectively) following conditioning with fludarabine, busulfan, and cyclophosphamide (FBC) for 84 consecutive patients with r/r T-cell malignancies. At start of conditioning LDH was elevated in 50% of cases, and residual tumor (PD, SD, PR) was detectable in 84% of patients. In total, 38% (95% CI 33-44) of the patients were alive and disease-free after a median observation time of 14.5 (range 1.8 to 114) months. Univariate and multivariate analyses identified low ECOG status, as well as occurrence of acute GvHD as favorable factors for outcome. Lymphoma-directed conditioning with fludarabin, busulfan and cyclophosphamid (FBC-12), and allogeneic stem cell transplantation resulted in long-term survival for a proportion of patients with r/r peripheral T-cell lymphoma, including those with PR and SD only after salvage therapy.