Fludarabine modulates composition and function of the T cell pool in patients with chronic lymphocytic leukaemia

An unveiling case of Nocardia pansinusitis in a patient with chronic lymphocytic leukemia: a case report

BACKGROUND

Nocardia infections are rare infections in immunocompetent patients and occur mostly in immunocompromised individuals. Usually, nocardia affects skin, brain, and lungs, but in disseminated forms, which occurred mostly in immunocompromised patients, it can involve every organ. Nocardia sinusitis is extremely rare as our searches returned only a very few related studies.

CASE PRESENTATION

In this case report, we present, for the first time, a 55-year-old Iranian male patient diagnosed with chronic lymphocytic leukemia who was receiving chemotherapeutic drugs and developed a fever. Further laboratory tests and imaging revealed pansinusitis. Following rhinoendoscopy, the sinus mucosal biopsy pathology report showed sever inflammation accompanied by aggregation of filamentous thin-walled bacteria. The patient was treated with co-trimoxazole and meropenem. Following good clinical improvement the patient was discharged and advised to continue oral co-trimoxazole for 3 months.

CONCLUSION

This case highlights that patients with febrile neutropenia should be assessed for rare infectious disease etiologies, especially those with chronic lymphocytic leukemia, as they have humeral immunodeficiency, and in the later stages of the disease, cellular immunodeficiency may also be involved. Therefore, a multisystem evaluation of patients with febrile neutropenia is necessary, particulary when no obvious source is identified in initial surveys, to uncover rare etiologies.

CD19-CAR T-cell therapy induces deep tissue depletion of B cells

OBJECTIVES

CD19-targeting chimeric antigen receptor (CAR) T-cell therapy can induce long-term drug-free remission in patients with autoimmune diseases (AIDs). The efficacy of CD19-CAR T-cell therapy is presumably based on deep tissue depletion of B cells; however, such effect has not been proven in humans in vivo.

METHODS

Sequential ultrasound-guided inguinal lymph node biopsies were performed at baseline and after CD19-CAR T-cell therapy in patients with AIDs. Results were compared with lymph node biopsies from rituximab (RTX)-treated AID patients with absence of peripheral B cells. Conventional and immunohistochemistry staining were performed on lymph node tissue to assess architecture as well the number of B cells, follicular dendritic cells (FDCs), plasma cells, T cells and macrophages.

RESULTS

Sequential lymph node biopsies were analysed from five patients with AID before and after CD19-CAR T-cell therapy and from five patients with AID after RTX treatment. In addition, non-lymphoid organ biopsies (colon, kidney and gallbladder) from three additional patients with AID after CD19-CAR T-cell therapy were analysed. CD19+ and CD20+ B cells were completely depleted in the lymph nodes after CD19-CAR T-cell therapy, but not after RTX treatment. Plasma cells, T cells and macrophages in the lymph nodes remained unchanged. Follicular structures were disrupted and FDCs were depleted in the lymph nodes after CD19-CAR T-cell therapy, but not after RTX. Non-lymphoid organs were completely depleted of B cells.

DISCUSSION

This study demonstrates complete B-cell depletion in secondary lymphoid tissues of patients with AIDs following CD19-CAR T-cell therapy combined with standard lymphodepleting therapy.

Impact of fludarabine and treosulfan on ovarian tumor cells and mesothelin chimeric antigen receptor T cells

In addition to their immunosuppressive effect, cytostatics conditioning prior to adoptive therapy such as chimeric antigen receptor (CAR) T cells may play a role in debulking and remodeling the tumor microenvironment. We investigated in vitro the killing efficacy and impact of treosulfan and fludarabine on ovarian cancer cells expressing mesothelin (MSLN) and effect on MSLN-targeting CAR T cells. Treosulfan and fludarabine had a synergetic effect on killing of SKOV3 and OVCAR4 cells. Sensitivity to the combination of treosulfan and fludarabine was increased when SKOV3 cells expressed MSLN and when OVCAR4 cells were tested in hypoxia, while MSLN cells surface expression by SKOV3 and OVCAR4 cells was not altered after treosulfan or fludarabine exposure. Exposure to treosulfan or fludarabine (10 µM) neither impacted MSLN-CAR T cells degranulation, cytokines production upon challenge with MSLN + OVCAR3 cells, nor induced mitochondrial defects. Combination of treosulfan and fludarabine decreased MSLN-CAR T cells anti-tumor killing in normoxia but not hypoxia. In conclusion, treosulfan and fludarabine killed MSLN + ovarian cancer cells without altering MSLN-CAR T cells functions (at low cytostatics concentration) even in hypoxic conditions, and our data support the use of treosulfan and fludarabine as conditioning drugs prior to MSLN-CAR T cell therapy.

Lymphodepletion - an essential but undervalued part of the chimeric antigen receptor T-cell therapy cycle

Lymphodepletion (LD) or conditioning is an essential step in the application of currently used autologous and allogeneic chimeric antigen receptor T-cell (CAR-T) therapies as it maximizes engraftment, efficacy and long-term survival of CAR-T. Its main modes of action are the depletion and modulation of endogenous lymphocytes, conditioning of the microenvironment for improved CAR-T expansion and persistence, and reduction of tumor load. However, most LD regimens provide a broad and fairly unspecific suppression of T-cells as well as other hematopoietic cells, which can also lead to severe side effects, particularly infections. We reviewed 1271 published studies (2011-2023) with regard to current LD strategies for approved anti-CD19 CAR-T products for large B cell lymphoma (LBCL). Fludarabine (Flu) and cyclophosphamide (Cy) (alone or in combination) were the most commonly used agents. A large number of different schemes and combinations have been reported. In the respective schemes, doses of Flu and Cy (range 75-120mg/m2 and 750-1.500mg/m2) and wash out times (range 2-5 days) differed substantially. Furthermore, combinations with other agents such as bendamustine (benda), busulfan or alemtuzumab (for allogeneic CAR-T) were described. This diversity creates a challenge but also an opportunity to investigate the impact of LD on cellular kinetics and clinical outcomes of CAR-T. Only 21 studies explicitly investigated in more detail the influence of LD on safety and efficacy. As Flu and Cy can potentially impact both the in vivo activity and toxicity of CAR-T, a more detailed analysis of LD outcomes will be needed before we are able to fully assess its impact on different T-cell subsets within the CAR-T product. The T2EVOLVE consortium propagates a strategic investigation of LD protocols for the development of optimized conditioning regimens.

A comprehensive assessment of lymphocyte subsets, their prognostic significance, and changes after first‐line therapy administration in patients with chronic lymphocytic leukemia

BACKGROUND

In chronic lymphocytic leukemia (CLL), changes in the peripheral blood lymphocyte subsets play an important role in disease progression and infectious complications. The impact of chemoimmunotherapy (CIT) on these changes has not been extensively studied METHODS: We used multi-color flow cytometry, to prospectively measure absolute and relative numbers of CD4⁺ and CD8⁺ T-cells and their subsets in 45 patients with indolent untreated CLL, 86 patients indicated for first-line treatment, and 34 healthy controls. In 55 patients, we analyzed the impact of CIT RESULTS: CLL patients had a significant increase in most cell populations in comparison to controls. Progression of CLL was characterized by significantly elevated counts with the exception of a lower percentage of naïve T-cells. After treatment, the percentage of naïve T-cells further decreased at the expense of effector memory T-cells (TEM). In patients with indolent CLL, higher percentages of naïve CD4⁺ (p = 0.0026) and naïve CD8⁺ (p = 0.023) T-cells were associated with a longer time to first treatment (TTFT). The elevation of CD4⁺ central memory T-cells (TCM) (p = 0.27) and TEM (p = 0.003) counts and a higher percentage of CD4⁺ TEM (p = 0.0047), were linked with shorter TTFT. In treated patients, increased regulatory T-cells count was associated with shorter time to next treatment (TTNT) (p = 0.042), while higher CD4⁺ TCM count with shorter TTNT (p = 0.035) and shorter overall survival (p = 0.041).

CONCLUSION

Our results indicate that naïve cell depletion and CD4⁺ TCM and TEM increases are detrimental to CLL patients' prognosis.

Insights from a patient with chronic lymphocytic leukemia complicating ALK+ anaplastic large cell lymphoma

Chronic lymphocytic leukemia (CLL) that transforms into a more aggressive lymphoma has been termed Richter syndrome (RS). CLL with T-cell neoplasia is rarely reported; those with ALK⁺ anaplastic large cell lymphoma (ALCL) are also exceedingly rarely reported. A 63-year-old woman from the south of China presented with generalized lymphadenectasis and fever; she already had a prior diagnosis of CLL 9 years ago. As per her current diagnosis, it was CLL with ALK⁺ ALCL. The two-lymph node and bone marrow biopsies presented two types of cellular groups: i) left cervical lymph node biopsy suggested CLL (Ki67: 10%), along with bone marrow biopsy exhibited enhancement of the small lymphocytes (30%) with scant cytoplasm, round or irregular cell nuclei, and massive amounts of chromatin. Large cells (< 1%) that expressed CD30 and ALK were visible; The results of immunohistochemistry were as follows: CD20 (weak positive); PAX5 (positive); CD23 and CD5 (weak positive); and CD3, CD10, and CyclinD1 (negative); ii) left supraclavicular lymph node biopsy suggested ALK⁺ ALCL (Ki67: 70%). The final diagnosis was CLL with ALCL. The mechanisms of this condition are not fully understood, which might be associated with chronic stimulation of T cells by CLL cells along with immune dysfunction.

The Emerging Role of CAR T Cell Therapy in Relapsed/Refractory Hodgkin Lymphoma

Treatment for Hodgkin lymphoma (HL) has evolved considerably from the time it was originally described in the 19th century with many patients now being cured with frontline therapy. Despite these advances, upwards of 10% of patients experience progressive disease after initial therapy with an even higher percentage relapsing. Until recently there had been limited therapeutic options for relapsed and/or refractory HL outside of highly intensive chemotherapy with stem cell rescue. Improved understanding of the pathophysiology of HL, coupled with the emergence of more targeted therapeutics, has reshaped how we view the treatment of relapsed/refractory HL and its prognosis. With this, there has been an increased focus on immunotherapies that can reprogram the immune system to better overcome the immunosuppressive milieu found in HL for improved cancer cell killing. In particular, chimeric antigen receptor (CAR) T cells are emerging as a valuable therapeutic tool in this area. Building on the success of antibody-drug conjugates directed against CD30, CAR T cells engineered to recognize the same antigen are now reaching patients. Though still in its infancy, CAR T therapy for relapsed/refractory HL has shown exceptional promise in early-stage clinical trials with the potential for durable responses even in patients who had progressed through multiple lines of prior therapy. Here we will review currently available data on the use of CAR T cells in HL, strategies to optimize their effectiveness, and how this therapy may fit into the treatment paradigm of HL going forward.

Humoral immune reconstitution after anti-BCMA CAR T-cell therapy in relapsed/refractory multiple myeloma

Systematic and dynamic humoral immune reconstitution is little-known for patients with relapsed/refractory (R/R) multiple myeloma (MM) who received anti-B-cell maturation antigen (BCMA) chimeric antigen receptor (CAR) T-cell therapy. We investigated the kinetics of B-cell, normal plasma cell, and immunoglobulin recovery in 40 patients who achieved ongoing response after anti-BCMA CAR T-cell therapy. All patients developed B-cell aplasia and the median duration of B-cell aplasia was 70 days (range, 23-270). The B-cell count reached its nadir on median day 7 and returned to baseline level on median day 97. BCMA+ cells in bone marrow turned undetectable on median day 28 (13-159) in 94.87% (37 of 39) of patients. Normal plasma cells in bone marrow were first redetected on median day 212. All patients developed a significant decrease in serum IgG, IgA, and IgM on median day 60. At year 1, recovery of serum IgG, IgM, and IgA was observed in 53.33% (8 of 15; non-IgG MM), 73.08% (19 of 26; non-IgM MM), and 23.81% (5 of 21;non-IgA MM) of the patients, respectively. Median time to IgG, IgM, and IgA recovery were days 386, 254, and not reached during follow-up, respectively. Virus-specific IgG levels decreased with loss of protection. Twenty-three of 40 (57.5%) patients had a total of 44 infection events. There were no infection-related deaths. These results reveal a 7-month aplasia of bone marrow normal plasma cells and longer period of hypogammaglobulinemia, suggesting a profound and lasting humoral immune deficiency after anti-BCMA CAR T-cell therapy, especially for IgA.

Angioimmunoblastic T-Cell Lymphoma and Chronic Lymphocytic Leukemia/Small Lymphocytic Lymphoma: A Novel Form of Composite Lymphoma Potentially Mimicking Richter Syndrome

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is an indolent small B-cell neoplasm that may transform into a clinically aggressive disease, namely Richter syndrome, usually as diffuse large B-cell lymphoma. Besides, CLL/SLL encompasses an increased risk of developing other secondary cancers, including a variety of T-cell lymphomas, often of the anaplastic large-cell type or with a cytotoxic phenotype. Here, we report a small series of patients with composite lymphomas consisting of CLL/SLL and angioimmunoblastic T-cell lymphoma (AITL), a hitherto unrecognized association. The 3 patients (1 male/2 females, 68 to 83 y) presented with high-grade-type symptoms. One patient was clinically suspicious for Richter syndrome, in the others CLL/SLL and AITL were concomitant de novo diagnoses. CLL/SLL and AITL were admixed in the same lymph nodes (3/3 cases) and in the bone marrow (1/2 cases). In all cases, the AITL comprised prominent clear cells with a strong T follicular helper immunophenotype and similar mutations consisting of TET2 or DNMT3A alterations, IDH2 R172K/M, and RHOA G17V. The 3 patients received chemotherapy. One died of early AITL relapse. The other 2 remained in complete remission of AITL, 1 died with recurrent CLL, and 1 of acute myeloid leukemia. These observations expand the spectrum of T-cell lymphoma entities that occur in association with CLL/SLL, adding AITL to the rare variants of aggressive neoplasms manifesting as Richter syndrome. Given that disturbances of T-cell homeostasis in CLL/SLL affect not only cytotoxic but also helper T-cell subsets, these may contribute to the emergence of neoplasms of T follicular helper derivation.

Colonization and immunoregulation of Lactobacillus plantarum BF_15, a novel probiotic strain from the feces of breast-fed infants

Immunosuppression is a manifestation imbalance in the immune system, often during unhealthy states. In recent years, lactic acid bacteria (LAB) have been found to be important components of the body's innate immune system, and indispensable to maintaining normal immune function. Lactobacillus plantarum BF_15, a novel strain isolated from the feces of breast-fed infants, which has shown potential as an immunomodulator in vitro. In the present study, with the Polymerase Chain Reaction-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) based on RNA-polymerase beta subunit encoding gene (rpoB) to analyze the colonization of L. plantarum BF_15 in the intestine of mice. In addition, Lactobacillus rhamnosus GG (LGG) as a positive control strain, by measuring immune-related indexes and the diversity of intestinal microbiota, the effects of BF_15 on immunoregulation and intestinal microbiota dysbiosis were investigated to elucidate whether the attenuation of immunosuppression is related to the modulation of intestinal microbiota. Results did indeed support this notion that BF_15 did colonize murine intestines well, in which it could still be detected in mice feces 14 days after stopping the probiotic administration. Moreover, BF_15 found to protect mice against reduction in the levels of several immune-related indicators, including the thymus and spleen indexes, splenic lymphocyte proliferation, toe swelling degree, serum hemolysin-antibody level, and macrophage phagocytosis index, triggered by high-dose (200 mg kg-1) intraperitoneal administration of cyclophosphamide (CTX). In addition, the strain was also found to effectively balance intestinal microbiota dysbiosis in the mice. Collectively, these results indicated that L. plantarum BF_15 can not only successfully colonize murine intestines, but also can effectively alleviate CTX-induced immunosuppression, once established, by rebalancing the intestinal microbiota. This, therefore, provides strong evidence for the view that BF_15 has the potential to become a highly effective immunomodulating probiotic in human microbiota as well.

Characteristics and outcome according to underlying disease in non-AIDS patients with acute respiratory failure due to Pneumocystis pneumonia

In the non-AIDS group, several underlying conditions and immune defects could lead to different PCP presentations. This study compared PCP presentation and outcome according to the underlying disease. A secondary analysis of a previously published prospective observational study including 544 PCP patients was done. Only non-AIDS patients were included. Underlying disease was defined as chronic lymphocytic leukemia (CLL), organ transplantation, solid cancer, allogeneic hematopoietic stem cell transplant (AHSCT), other hematological diseases, and immunosuppressive treatment. Clinical characteristics and outcomes were compared between groups. Multiple correspondent analyses compared clinical characteristics at diagnosis. Day 30 mortality was analyzed. Three hundred and twenty-one patients were included in the study. The underlying diseases were hematological malignancy (n = 75), AHSCT (n = 14), CLL (n = 19), solid organ transplant (n = 94), solid tumor (n = 39), and immunosuppressive treatment (n = 57). Compared with other underlying diseases, PCP related to CLL was closer to PCP related to AIDS presentation (long duration of symptoms before diagnosis, high level of dyspnea, and low oxygen saturation at diagnosis). Day 30 mortality was associated with underlying disease, oxygen flow, and shock at ICU admission. PCP presentations may vary according to the underlying reason for immunosuppression. Response to treatment and adjuvant steroid therapy should be analyzed regarding this result.

Tumor response and endogenous immune reactivity after administration of HER2 CAR T cells in a child with metastatic rhabdomyosarcoma

Refractory metastatic rhabdomyosarcoma is largely incurable. Here we analyze the response of a child with refractory bone marrow metastatic rhabdomyosarcoma to autologous HER2 CAR T cells. Three cycles of HER2 CAR T cells given after lymphodepleting chemotherapy induces remission which is consolidated with four more CAR T-cell infusions without lymphodepletion. Longitudinal immune-monitoring reveals remodeling of the T-cell receptor repertoire with immunodominant clones and serum autoantibodies reactive to oncogenic signaling pathway proteins. The disease relapses in the bone marrow at six months off-therapy. A second remission is achieved after one cycle of lymphodepletion and HER2 CAR T cells. Response consolidation with additional CAR T-cell infusions includes pembrolizumab to improve their efficacy. The patient described here is a participant in an ongoing phase I trial (NCT00902044; active, not recruiting), and is 20 months off T-cell infusions with no detectable disease at the time of this report.

Next-generation CAR T cells to overcome current drawbacks

As a rapidly emerging treatment in the oncology field, adoptive transfer of autologous, genetically modified chimeric antigen receptor (CAR) T cells has shown striking efficacy and is curative in certain relapsed/refractory patients with hematologic malignancy. This treatment modality of using a "living drug" offers many tantalizing and novel therapeutic strategies for cancer patients whose remaining treatment options may have otherwise been limited. Despite the early success of CAR T cells in hematologic malignancies, many barriers remain for widespread adoption. General barriers include cellular manufacturing limitations, baseline quality of the T cells, adverse events post-infusion such as cytokine release syndrome (CRS) and neurotoxicity, and host rejection of non-human CARs. Additionally, each hematologic disease presents unique mechanisms of relapse which have to be addressed in future clinical trials if we are to augment the efficacy of CAR T treatment. In this review, we will describe current barriers to hindering efficacy of CAR T-cell treatment for hematologic malignancies in a disease-specific manner and review recent innovations aimed at enhancing the potency and applicability of CAR T cells, with the overall goal of building a framework to begin incorporating this form of therapy into the standard medical management of blood cancers.

Invasive fungal infections in the immunocompromised host: Mechanistic insights in an era of changing immunotherapeutics

The use of cytotoxic chemotherapy in the treatment of malignant and inflammatory disorders is beset by considerable adverse effects related to nonspecific cytotoxicity. Accordingly, a mechanistic approach to therapeutics has evolved in recent times with small molecular inhibitors of intracellular signaling pathways involved in disease pathogenesis being developed for clinical use, some with unparalleled efficacy and tolerability. Nevertheless, there are emerging concerns regarding an association with certain small molecular inhibitors and opportunistic infections, including invasive fungal diseases. This is perhaps unsurprising, given that the molecular targets of such agents play fundamental and multifaceted roles in orchestrating innate and adaptive immune responses. Nevertheless, some small molecular inhibitors appear to possess intrinsic antifungal activity and may therefore represent novel therapeutic options in future. This is particularly important given that antifungal resistance is a significant, emerging concern. This paper is a comprehensive review of the state-of-the-art in the molecular immunology to fungal pathogens as applied to existing and emerging small molecular inhibitors.

Chronic lymphocytic leukaemia: the role of T cells in a B cell disease

Chronic lymphocytic leukaemia (CLL) has long been thought to be an immunosuppressive disease and abnormalities in T-cell subset distribution and function have been observed in many studies. However, the role of T cells (if any) in disease progression remains unclear and has not been directly studied. This has changed with the advent of new therapies, such as chimeric antigen receptor-T cells, which actively use retargeted patient-derived T cells as "living drugs" for CLL. However complete responses are relatively low (~26%) and recent studies have suggested the differentiation status of patient T cells before therapy may influence efficacy. Non-chemotherapeutic drugs, such as idelalisib and ibrutinib, also have an impact on T cell populations in CLL patients. This review will highlight what is known about T cells in CLL during disease progression and after treatment, and discuss the prospects of using T cells as predictive biomarkers for immune status and response to therapy.

Remission maintenance treatment options in chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL) treatment has come a long way in the last two decades, producing increases in tumor control to the point of generating sizeable numbers of patients with undetectable minimal residual disease and creating overall survival benefits in randomized comparisons. Most of this has been achieved by limited-term treatment approaches including chemotherapeutic and immune-therapeutic drugs. More recently, novel therapies targeting signaling pathways essential for the survival of the neoplastic clones have opened avenues that provide disease control in long-term treatment designs, mostly without producing deep remissions. In this disease, where current treatments are largely unable to effect a cure, prolonged therapy designs using maintenance approaches are explored and 5 randomized studies of maintenance have recently been published. This review shall summarize available results from a systematic literature review in a clinical context and outline basic biology principles that should be heeded in this regard.

Fludarabine and rituximab with escalating doses of lenalidomide followed by lenalidomide/rituximab maintenance in previously untreated chronic lymphocytic leukaemia (CLL): the REVLIRIT CLL-5 AGMT phase I/II study

Despite recent advances, chemoimmunotherapy remains a standard for fit previously untreated chronic lymphocytic leukaemia patients. Lenalidomide had activity in early monotherapy trials, but tumour lysis and flare proved major obstacles in its development. We combined lenalidomide in increasing doses with six cycles of fludarabine and rituximab (FR), followed by lenalidomide/rituximab maintenance. In 45 chemo-naive patients, included in this trial, individual tolerability of the combination was highly divergent and no systematic toxicity determining a maximum tolerated dose was found. Grade 3/4 neutropenia (71%) was high, but only 7% experienced grade 3 infections. No tumour lysis or flare > grade 2 was observed, but skin toxicity proved dose-limiting in nine patients (20%). Overall and complete response rates after induction were 89 and 44% by intention-to-treat, respectively. At a median follow-up of 78.7 months, median progression-free survival (PFS) was 60.3 months. Minimal residual disease and immunoglobulin variable region heavy chain mutation state predicted PFS and TP53 mutation most strongly predicted OS. Baseline clinical factors did not predict tolerance to the immunomodulatory drug lenalidomide, but pretreatment immunophenotypes of T cells showed exhausted memory CD4 cells to predict early dose-limiting non-haematologic events. Overall, combining lenalidomide with FR was feasible and effective, but individual changes in the immune system seemed associated with limiting side effects. clinicaltrials.gov (NCT00738829) and EU Clinical Trials Register (www.clinicaltrialsregister.eu, 2008-001430-27)

A blood dendritic cell vaccine for acute myeloid leukemia expands anti-tumor T cell responses at remission

Only modest advances in AML therapy have occurred in the past decade and relapse due to residual disease remains the major challenge. The potential of the immune system to address this is evident in the success of allogeneic transplantation, however this leads to considerable morbidity. Dendritic cell (DC) vaccination can generate leukemia-specific autologous immunity with little toxicity. Promising results have been achieved with vaccines developed in vitro from purified monocytes (Mo-DC). We now demonstrate that blood DC (BDC) have superior function to Mo-DC. Whilst BDC are reduced at diagnosis in AML, they recover following chemotherapy and allogeneic transplantation, can be purified using CMRF-56 antibody technology, and can stimulate functional T cell responses. While most AML patients in remission had a relatively normal T cell landscape, those who had received fludarabine as salvage therapy have persistent T cell abnormalities including reduced number, altered subset distribution, failure to expand, and increased activation-induced cell death. Furthermore, PD-1 and TIM-3 are increased on CD4T cells in AML patients in remission and their blockade enhances the expansion of leukemia-specific T cells. This confirms the feasibility of a BDC vaccine to consolidate remission in AML and suggests it should be tested in conjunction with checkpoint blockade.

Persistently low lymphocyte counts after FCR therapy for chronic lymphocytic leukemia are associated with longer overall survival

Decreased absolute lymphocyte counts (ALCs) following frontline therapy for chronic lymphocytic leukemia may be associated with disease control, even in patients without evidence of minimal residual disease. We studied the prognostic significance of ALCs during the first year following treatment with fludarabine, cyclophosphamide, and rituximab (FCR). We evaluated 99 patients who achieved a partial response without lymphocytosis (<4.0 × 10³ cells/μL) or better after FCR. Absolute lymphocyte counts were recorded at 3-, 6-, 9-, and 12-month posttreatment and correlated with overall survival (OS) and event-free survival (EFS). For each time point, analyses were limited to patients without lymphocytosis, so as to avoid possible biases from undocumented disease progressions. Lymphopenia (ALC < 1.0 × 10³ cells/μL) at 3 m after FCR (69% of patients n = 68), was associated with a longer OS (5y OS 91% vs 64%, P = .001), as were ALC ≤ 2 × 10³ cells/μL at 6 m (5y OS 85% vs 48%, P = .004) and ALC ≤ 1.8 × 10³ cells/μL at 9 m (5y OS 93% vs 54%, P = .009). A normal-range ALC (≤4 × 10³ cells/μL) at 12 m was also associated with a 91% 5y OS. Higher ALCs (but without lymphocytosis) were associated with shorter EFS (median EFS 27 months for ALC > 1.8 vs not reached for ALC ≤ 0.7 at 9 months, P < .0001). In conclusion, lower ALC levels in the first few months following frontline FCR therapy were associated with longer OS and EFS. Possible explanations may be that lower ALCs reflect deeper clonal suppression or protracted T_reg depletion. Absolute lymphocyte count levels may be a cheap and widely available prognostic marker, though the added value for clinical practice is the minimal residual disease era needs to be explored.

Chronic lymphocytic leukemia and small lymphocytic lymphoma: two faces of the same disease

INTRODUCTION

Chronic lymphocytic leukemia (CLL) and small lymphocytic lymphoma (SLL) are considered indolent lymphocytic malignancies, more often requiring active surveillance rather than intervention. Despite the indolent nature of CLL/SLL, treatment is likely indicated in a patients' lifetime. Recent changes in the therapeutic landscape have created more options to the clinician. Areas covered: The authors provide a broad assessment of the current state of disease, including the work-up, prognostic features, and mutational aspects of the disease that should be acknowledged when developing a rational treatment plan. Key studies, guideline recommendations, and expert analysis are used to create this update on CLL/SLL. Expert commentary: The recent pace of treatment additions in CLL/SLL is a welcome addition. Moving forward, it is anticipated that treatment modalities will continue to evolve, leading to additional management options that truly would define CLL/SLL as a chronic disease.

T cells in chronic lymphocytic leukemia display dysregulated expression of immune checkpoints and activation markers

Chronic lymphocytic leukemia is characterized by impaired immune functions largely due to profound T-cell defects. T-cell functions also depend on co-signaling receptors, inhibitory or stimulatory, known as immune checkpoints, including cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) and programmed death-1 (PD-1). Here we analyzed the T-cell phenotype focusing on immune checkpoints and activation markers in chronic lymphocytic leukemia patients (n=80) with different clinical characteristics and compared them to healthy controls. In general, patients had higher absolute numbers of CD3⁺ cells and the CD8⁺ subset was particularly expanded in previously treated patients. Progressive patients had higher numbers of CD4⁺ and CD8⁺ cells expressing PD-1 compared to healthy controls, which was more pronounced in previously treated patients (P=0.0003 and P=0.001, respectively). A significant increase in antigen-experienced T cells was observed in patients within both the CD4⁺ and CD8⁺ subsets, with a significantly higher PD-1 expression. Higher numbers of CD4⁺ and CD8⁺ cells with intracellular CTLA-4 were observed in patients, as well as high numbers of proliferating (Ki67⁺) and activated (CD69⁺) CD4⁺ and CD8⁺ cells, more pronounced in patients with active disease. The numbers of Th1, Th2, Th17 and regulatory T cells were substantially increased in patients compared to controls (P<0.05), albeit decreasing to low levels in pre-treated patients. In conclusion, chronic lymphocytic leukemia T cells display increased expression of immune checkpoints, abnormal subset distribution, and a higher proportion of proliferating cells compared to healthy T cells. Disease activity and previous treatment shape the T-cell profile of chronic lymphocytic leukemia patients in different ways.

Fludarabine in the Treatment of Refractory Chronic Inflammatory Demyelinating Neuropathies

Inflammatory demyelinating neuropathies have variable responses to immunomodulating therapy. Eight patients with chronic inflammatory neuropathies who were refractory to standard therapy were treated with fludarabine, a combination of fludarabine and cyclophosphamide, and in 1 case with fludarabine and rituximab. Five patients with immunoglobulin M anti-myelin-associated glycoprotein neuropathies received fludarabine. Three patients with chronic inflammatory demyelinating polyneuropathy received a combination of fludarabine and cyclophosphamide. All 8 patients improved in either functional status or strength with minimal toxicities. Most patients experienced sustained remission after the use of fludarabine or fludarabine and cyclophosphamide. Fludarabine alone or in combination with cyclophosphamide should be considered for patients with inflammatory demyelinating neuropathies, refractory to other treatments.

Chronic lymphocytic leukaemia induces an exhausted T cell phenotype in the TCL1 transgenic mouse model

Although chronic lymphocytic leukaemia (CLL) is a B cell malignancy, earlier studies have indicated a role of T cells in tumour growth and disease progression. In particular, the functional silencing of antigen-experienced T cells, called T cell exhaustion, has become implicated in immune evasion in CLL. In this study, we tested whether T cell exhaustion is recapitulated in the TCL1(tg) mouse model for CLL. We show that T cells express high levels of the inhibitory exhaustion markers programmed cell death 1 (PDCD1, also termed PD-1) and lymphocyte-activation gene 3 (LAG3), whereas CLL cells express high levels of CD274 (also termed PD-ligand 1). In addition, the fraction of exhausted T cells increases with CLL progression. Finally, we demonstrate that exhausted T cells are reinvigorated towards CLL cytotoxicity by inhibition of PDCD1/CD274 interaction in vivo. These results suggest that T cell exhaustion contributes to CLL pathogenesis and that interference with PDCD1/CD274 signalling holds high potential for therapeutic approaches.

Successful transplantation of kidney allografts in sensitized rats after syngeneic hematopoietic stem cell transplantation and fludarabine

Current methods to remove donor-specific HLA antibody (DSA) from sensitized patients remain imperfect. We tested novel approaches to desensitization using an animal model of allogeneic sensitization with skin grafts from dark agouti (DA) to Lewis rats. At the peak IgG alloantibody response we transplanted DA kidneys into nephrectomized Lewis recipients (n = 6) and all died within 10 days from antibody-mediated rejection (AMR). Allogeneic hematopoietic stem cell transplants (HSCT) from DA donors failed to engraft after lethal or sub-lethal irradiation. Sensitized rats given lethal irradiation plus syngeneic green fluorescent protein (GFP) + HSCT had repopulation of blood, spleen, thymus and lymph nodes by GFP+ cells. At 2 months after HSCT, serum DSA levels were reduced 60-70% and DSA (IgG) production in cultured splenocytes was also significantly decreased. However, there was only a modest improvement in graft survival from an average of 6.5 to 13.9 (n = 9) days. Adding seven daily doses of fludarabine to the preconditioning regimen resulted in long-term survival (>90 days) in 7 out of 10 rat kidney allografts. We conclude that syngeneic HSCT performed after preconditioning with irradiation and fludarabine can reduce DSA, prevent DSA rebound and AMR, enabling successful transplantation in animals with strong antibody reactivity to the donor MHC.

Therapeutic vaccines for cancer: an overview of clinical trials

The therapeutic potential of host-specific and tumour-specific immune responses is well recognized and, after many years, active immunotherapies directed at inducing or augmenting these responses are entering clinical practice. Antitumour immunization is a complex, multi-component task, and the optimal combinations of antigens, adjuvants, delivery vehicles and routes of administration are not yet identified. Active immunotherapy must also address the immunosuppressive and tolerogenic mechanisms deployed by tumours. This Review provides an overview of new results from clinical studies of therapeutic cancer vaccines directed against tumour-associated antigens and discusses their implications for the use of active immunotherapy.

Peripheral T-cell lymphomas with cytotoxic phenotype in patients with chronic lymphocytic leukemia/small lymphocytic lymphoma

Chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) is relatively common, and patients occasionally develop other neoplasms; however, patients who develop other types of lymphomas are rare. We encountered 3 patients with CLL/SLL (one 59-y-old man and 2 women aged 56 and 66 y) who developed T-cell lymphomas. Both women developed ALK anaplastic large cell lymphomas (ALCLs), whereas the man developed CD8 peripheral T-cell lymphoma, not otherwise specified. All 3 T-cell lymphomas expressed granzyme B and perforin, indicating a cytotoxic immunophenotype. In 1 case, the first presentation was a lymph nodal composite lymphoma. In the other 2 cases, the T-cell lymphomas arose <1 year after the diagnosis of CLL/SLL and were identified in a lymph node in one case and in the spleen in the other. The patient with a composite lymphoma (SLL/ALK ALCL) was treated and was free of disease at last follow-up, whereas the other 2 patients succumbed to their disease, 1 month and 7 months after the diagnosis of T-cell lymphoma. Peripheral T-cell lymphomas rarely occur in CLL/SLL patients. On the basis of our small series, those with a cytotoxic phenotype appear to be more common in this setting. The occurrence of ALK ALCL in 2 older patients was especially surprising and suggested that CLL/SLL may have played a role in the development of ALCL.

Understanding the immunodeficiency in chronic lymphocytic leukemia: potential clinical implications

Chronic lymphocytic leukemia (CLL) is the most common leukemia in adults. Although significant advances have been made in the treatment of CLL in the last decade, it remains incurable. Treatments may be too toxic for some elderly patients, who constitute most of the individuals with this disease, and there remain subgroups of patients for which this therapy has minimal activity. This article summarizes the current understanding of the immune defects in CLL. It also examines the potential clinical implications of these findings.