Petros Christopoulos

Definition and characterization of the systemic T-cell dysregulation in untreated indolent B-cell lymphoma and very early CLL

Epidemiologic data show that the immune system may control or promote the emergence and growth of neoplastic lymphomatous clones. Conversely, systemic lymphomas, especially myeloma and chronic lymphocytic leukemia (CLL), are associated with clinical immunodeficiency. This prospective controlled study demonstrates substantially reduced circulating T helper cells, predominantly naive CD4(+) cells, in patients with nonleukemic follicular lymphoma and extranodal marginal zone lymphoma, but not in monoclonal gammopathy and early CLL. These changes were correlated with a preactivated phenotype, hyperreactivity in vitro, pre-senescence, and a T helper 2 shift of peripheral T helper cells. No prominent alterations existed in the regulatory T-cell compartment. Gene expression profiling of in vitro-stimulated CD4(+) cells revealed an independent second alteration of T helper cell physiology, which was most pronounced in early CLL but also detectable in follicular lymphoma/extranodal marginal zone lymphoma. This pattern consisted of down-regulation of T-cell receptor signaling cascades and globally reduced cytokine secretion. Both types of T-cell dysfunction may contribute to significant immunodeficiency in nonleukemic indolent B-cell lymphomas as demonstrated by unresponsiveness to hepatitis B vaccination. The precise definition of systemic T-cell dysfunction serves as the basis to study its prognostic impact, its relationship to the established influence of the lymphoma microenvironment, and its therapeutic manipulation.

A Novel Thymoma-Associated Immunodeficiency with Increased Naive T Cells and Reduced CD247 Expression

The mechanisms underlying thymoma-associated immunodeficiency are largely unknown, and the significance of increased blood γδ Τ cells often remains elusive. In this study we address these questions based on an index patient with thymoma, chronic visceral leishmaniasis, myasthenia gravis, and a marked increase of rare γδ T cell subsets in the peripheral blood. This patient showed cutaneous anergy, even though he had normal numbers of peripheral blood total lymphocytes as well as CD4+ and CD8+ T cells. Despite his chronic infection, analyses of immunophenotypes and spectratyping of his lymphocytes revealed an unusual accumulation of naive γδ and αβ T cells, suggesting a generalized T cell activation defect. Functional studies in vitro demonstrated substantially diminished IL-2 and IFN-γ production following TCR stimulation of his “untouched” naive CD4+ T cells. Biochemical analysis revealed that his γδ and αβ T cells carried an altered TCR complex with reduced amounts of the ζ-chain (CD247). No mutations were found in the CD247 gene that encodes the homodimeric ζ protein. The diminished presence of CD247 and increased numbers of γδ T cells were also observed in thymocyte populations obtained from three other thymoma patients. Thus, our findings describe a novel type of a clinically relevant acquired T cell immunodeficiency in thymoma patients that is distinct from Good’s syndrome. Its characteristics are an accumulation of CD247-deficient, hyporresponsive naive γδ and αβ T cells and an increased susceptibility to infections.

Radiation-Free Allogeneic Conditioning with Fludarabine, Carmustine, and Thiotepa for Acute Lymphoblastic Leukemia and Other Hematologic Malignancies Necessitating Enhanced Central Nervous System Activity

Total body irradiation has been the mainstay of conditioning since the inception of allogeneic hematopoietic cell transplantation, but toxicity often precludes its use. For less-fit patients with acute lymphoblastic leukemia and other hematologic malignancies frequently affecting the central nervous system, we designed a radiation-free regimen with fludarabine (25 mg/m2/day on days -6 to -4), carmustine (400 mg/m2 on day -6), and thiotepa (5 mg/kg twice daily on days -5 and -4), all of which readily penetrate the blood-brain barrier and have potent antileukemic and lymphotoxic activity. Here we present a series of 30 consecutive patients with high-risk or relapsed disease who underwent allogeneic hematopoietic cell transplantation with this protocol. The median patient age was 60 years (range, 42-70 years), and the median follow-up was 968 days (range, 58-1989 days). Graft-versus-host disease prophylaxis consisted of cyclosporine A and alemtuzumab (10-20 mg). At 2 years, overall survival was 52% (95% confidence interval [CI], 34%-71%), event-free survival was 39% (95% CI, 22%-57%), cumulative incidence of relapse/progression was 30% (95% CI, 17%-52%), and treatment-related mortality was 31% (95% CI, 18%-53%). Neurologic toxicity is a concern, especially in older and heavily pretreated patients. Our experience indicates the feasibility of this regimen as an alternative to total body irradiation and a potentially curative option for less-fit patients who need a highly central nervous system-active conditioning.

Acquired T-Cell Immunodeficiency in Thymoma Patients

Acquired T-cell immunodeficiency can occur in thymoma patients with or without hypogammaglobulinemia (Goods syndrome), but it has received little attention to date. It appears predominantly associated with lymphocyte-rich (i.e., cortical or mixed) thymomas and frequently coexists with autoimmune manifestations. The main abnormalities are an increase in circulating naive T cells, cutaneous T-cell anergy, TCR hyporesponsiveness in vitro as well as a numerical and functional impairment of regulatory T cells. All of these probably result from an abnormal T-cell maturation in the neoplastic thymic microenvironment. A better understanding of thymoma-related acquired T-cell immunodeficiency will be important for immunotherapy of this orphan disease as well as for the prevention and treatment of opportunistic infections, autoimmune complications and secondary malignancies that contribute to the morbidity and mortality of thymoma patients.

Large cell neuroendocrine lung carcinoma induces peripheral T-cell repertoire alterations with predictive and prognostic significance

OBJECTIVES This study was performed to evaluate for a potentially important role of T cells in the pathophysiology and treatment sensitivity of large cell neuroendocrine lung carcinoma (LCNEC), an orphan disease with poor prognosis and scarce data to guide novel therapeutic strategies. MATERIALS AND METHODS We performed T-cell receptor (TCR) β-chain spectratyping on blood samples of patients treated within the CRAD001KDE37 trial (n = 35) using age-matched current or former (n = 11) and never smokers (n = 10) as controls. The data were analyzed in conjunction with the complete blood counts of the probands as well as the data about response to treatment and overall survival in the clinical trial. RESULTS AND CONCLUSION Untreated stage IV LCNEC patients had significant T-cell repertoire alterations (p < 0.001) compared to age-matched smokers. These changes correlated positively with blood lymphocyte counts (r = 0.49, p < 0.01), suggesting antigen-induced T-cell proliferation as the causative mechanism. At the same time, LCNEC patients showed mild lymphopenia (1.54 vs. 2.51/nl in median, p < 0.01), which reveals a second, antigen-independent mechanism of systemic immune dysregulation. More pronounced T-cell repertoire alterations and higher blood lymphocyte counts at diagnosis were associated with a better treatment response by RECIST and with a longer overall survival (441 vs. 157 days in median, p = 0.019). A higher degree of T-cell repertoire normalization after 3 months of therapy also distinguished a patient group with more favourable prognosis (median overall survival 617 vs. 316 days, p = 0.036) independent of radiological response. Thus, LCNEC induces clinically relevant changes of the T-cell repertoire, which are measurable in the blood and could be exploited for prognostic, predictive and therapeutic purposes. Their pathogenesis appears to involve antigen-induced oligoclonal T-cell expansions superimposed on TCR-independent lymphopenia.

EML4-ALK V3, treatment resistance, and survival: refining the diagnosis of ALK + NSCLC

Anaplastic lymphoma kinase ( ALK ) gene fusions drive approximately 5% of non-small cell lung cancers (NSCLC) (1). Fluorescence in situ hybridization (FISH) and immunohistochemistry are widely used to identify them based on ALK translocation and ALK overexpression, which are common in all cases and equally predict response to tyrosine kinase inhibitors (TKI) (2). On the other hand, the ALK fusion itself varies among patients.

A mighty oak in the rapidly expanding field of checkpoint inhibition for NSCLC

In the Lancet issue of last December Rittmeyer and colleagues reported the primary efficacy analysis of another landmark immunotherapy study (1): the randomized phase 3 OAK trial comparing atezolizumab (n=425), an anti-programmed death-ligand 1 (PD-L1) monoclonal antibody, with docetaxel (n=425) for patients with squamous or adenocarcinomatous non-small cell lung cancer (NSCLC) progressing after one or more platinum-based combination regimens.

Improved analysis of TCRγδ variable region expression in humans.

Deeper understanding of γδ Τ cell increases in various clinical situations requires the assessment of TCRγ and δ variable (V) region gene expression and junctional diversity. Here we describe an improved TCRγ and δ spectratyping method used to study the γδ T-cell expansions in two patients with thymoma and immunodeficiency. One of these patients also suffered from chronic CMV infection and pure red cell aplasia and the other from chronic visceral leishmaniasis and myasthenia gravis. Analyses of the junctional diversity of the TCRγ and δ chains, flow cytometry with a panel of non-commercially available anti-TCRγδ V region monoclonal antibodies and functional studies were performed. The results clearly distinguished an expansion of oligoclonal, most likely antigen-driven, cytotoxic γδ T cells in the first patient from a naive pattern of polyclonal γδ T-cell proliferation in the second. These findings demonstrate the diversity of γδ T-cell expansions in immunodeficient patients and highlight the value of spectratyping as a tool for their characterization and understanding of the underlying mechanisms.

Response to Comment on “A Novel Thymoma-Associated Immunodeficiency with Increased Naive T Cells and Reduced CD247 Expression”

We thank Dr. Welch and Dr. Howard for their comments on our recent study ([1][1]). CD247, a subunit of the TCRαβ and TCRγδ, is often downmodulated in effector and memory T cells in animals and patients with chronic inflammatory conditions such as autoimmune and infectious diseases, as well as

Molecular and functional analysis of γδ T cell expansions in immunodeficient patients

Methods and results Two adult patients with thymoma and γδ T cell expansions were studied by flow cytometry and T cell receptor γand δ-chain spectratyping. One patient suffering from leishmaniasis and thymic carcinoma showed a peculiar polyclonal γδ T cell proliferation while another patient with a benign thymoma and CMV reactivation had a persistent oligoclonal amplification of γδ T cells. In one pediatric patient with incomplete RAG-1 deficiency, we found a restricted variability of the expressed Vδ3, versus Vδ1 and Vδ2 chains and a seemingly monoclonal usage of the Vγ4 element. Sequencing revealed that these γδ T cells showed significant junctional diversity. These data suggested selection of the γδ T cells by antigens such as CMV infection. Indeed, 4 out of 5 δ T cell clones that could be derived from this patient secreted TNFα in response to CMV infected allogeneic fibroblasts.