T Cell Defects and Immunotherapy in Chronic Lymphocytic Leukemia

Immunotherapy response in immunosuppressed patients with Merkel cell carcinoma: analysis of 183 patients

Objective

Merkel cell carcinoma (MCC) is an aggressive skin cancer with poor outcomes in immunosuppressed patients. While immune checkpoint inhibitors (ICIs) achieve ~60% response rates in immunocompetent MCC patients, their efficacy in immunosuppressed patients remains unclear due to exclusion from trials. This study compares ICI outcomes, safety and the impact of immunosuppression subtypes between these groups.

Methods and analysis

This retrospective study analysed 183 advanced MCC patients on first-line ICIs from a Seattle-based data repository. Of these, 147 were immunocompetent, and 36 were immunosuppressed (chronic lymphocytic leukaemia (CLL) n=10, autoimmune disorders n=10, other haematologic malignancies n=9, solid organ transplants n=4 and HIV/AIDS n=3). Outcomes included objective response rate, disease progression, MCC-specific and overall survival probability, adjusted for age, sex and stage at ICI initiation.

Results

Initial ICI response rates at 6 months were 50% in immunosuppressed and 61.5% in immunocompetent patients (HR=0.71, p=0.17). Immunosuppressed patients had higher risks of disease progression (2 years: 53.9% vs 42.1%, HR=1.65, p=0.05) and MCC-specific mortality (2 years: 38.7% vs 24.4%, HR=1.85, p=0.04). CLL patients (n=10) had a particularly low response rate (response rate: 20.0% vs 61.5%, HR=0.18, p=0.02) and high progression risk (2 years: 80.0% vs 42.1%, HR=4.09, p=0.01). Immunosuppressed patients faced higher rates of ICI toxicity (6-month risk: 51.6% vs 36.6%, HR=1.79, p=0.03).

Conclusions

ICIs provide meaningful benefits to immunosuppressed MCC patients, though their response rates are lower, and progression risk is higher compared with immunocompetent patients.

Raman spectroscopy and bioinformatics-based identification of key genes and pathways capable of distinguishing between diffuse large B cell lymphoma and chronic lymphocytic leukemia

Diffuse large B-cell lymphoma (DLBCL) and chronic lymphocytic leukemia (CLL) are subtypes of non-Hogkin lymphoma (NHL) that are generally distinct form one cases, but the transformation of one of these diseases into the other is possible. Some patients with CLL, for instance, have the potential to develop Richter transformation such that they are diagnosed with a rare, invasive DLBCL subtype. In this study, bioinformatics analyses of these two NHL subtypes were conducted, identifying key patterns of gene expression and then experimentally validating the results. Disease-related gene expression datasets from the GEO database were used to identify differentially expressed genes (DEGs) and DEG functions were examined using GO analysis and protein-protein interaction network construction. This strategy revealed many up- and down-regulated DEGs, with functional enrichment analyses identifying these genes as being closely associated with inflammatory and immune response activity. PPI network analyses and the evaluation of clustered network modules indicated the top 10 up- and down-regulated genes involved in disease onset and development. Serological analyses revealed significantly higher ALB, TT, and WBC levels in CLL patients relative to DLBCL patients, whereas the opposite was true with respect to TG, HDL, GGT, ALP, ALT, and NEUT% levels. In comparison to the CLL and DLBCL groups, the healthy control samples demonstrated higher signals of protein peak positions (621, 643, 848, 853, 869, 935, 1003, 1031, 1221, 1230, 1260, 1344, 1443, 1446, 1548, 1579, 1603, 1647 cm-1), nucleic acid peak positions (726, 781, 786, 1078, 1190, 1415, 1573, 1579 cm-1), beta carotene peak positions (957, 1155, 1162 cm-1), carbohydrate peak positions (842 cm-1), collagen peak positions (1345 cm-1), and lipid peak positions (957, 1078, 1119, 1285, 1299, 1437, 1443, 1446 cm-1) compared to the CLL and DLBCL groups. Verification of these key genes in patient samples yielded results consistent with findings derived from bioinformatics analyses, highlighting their relevance to diagnosing and treating these forms of NHL. Together, these analyses identified genes and pathways involved in both DLBCL and CLL. The set of molecular markers established herein can aid in patient diagnosis and prognostic evaluation, providing a valuable foundation for their therapeutic application.

Role of the tumor microenvironment in CLL pathogenesis

Chronic lymphocytic leukemia (CLL) cells extensively interact with and depend on their surrounding tumor microenvironment (TME). The TME encompasses a heterogeneous array of cell types, soluble signals, and extracellular vesicles, which contribute significantly to CLL pathogenesis. CLL cells and the TME cooperatively generate a chronic inflammatory milieu, which reciprocally reprograms the TME and activates a signaling network within CLL cells, promoting their survival and proliferation. Additionally, the inflammatory milieu exerts chemotactic effects, attracting CLL cells and other immune cells to the lymphoid tissues. The intricate CLL-TME interactions also facilitate immune evasion and compromise leukemic cell surveillance. We also review recent advances that have shed light on additional aspects that are substantially influenced by the CLL-TME interplay.

T cell receptor gene repertoire profiles in subgroups of patients with chronic lymphocytic leukemia bearing distinct genomic aberrations

Background

Microenvironmental interactions of the malignant clone with T cells are critical throughout the natural history of chronic lymphocytic leukemia (CLL). Indeed, clonal expansions of T cells and shared clonotypes exist between different CLL patients, strongly implying clonal selection by antigens. Moreover, immunogenic neoepitopes have been isolated from the clonotypic B cell receptor immunoglobulin sequences, offering a rationale for immunotherapeutic approaches. Here, we interrogated the T cell receptor (TR) gene repertoire of CLL patients with different genomic aberration profiles aiming to identify unique signatures that would point towards an additional source of immunogenic neoepitopes for T cells.

Experimental design

TR gene repertoire profiling using next generation sequencing in groups of patients with CLL carrying one of the following copy-number aberrations (CNAs): del(11q), del(17p), del(13q), trisomy 12, or gene mutations in TP53 or NOTCH1.

Results

Oligoclonal expansions were found in all patients with distinct recurrent genomic aberrations; these were more pronounced in cases bearing CNAs, particularly trisomy 12, rather than gene mutations. Shared clonotypes were found both within and across groups, which appeared to be CLL-biased based on extensive comparisons against TR databases from various entities. Moreover, in silico analysis identified TR clonotypes with high binding affinity to neoepitopes predicted to arise from TP53 and NOTCH1 mutations.

Conclusions

Distinct TR repertoire profiles were identified in groups of patients with CLL bearing different genomic aberrations, alluding to distinct selection processes. Abnormal protein expression and gene dosage effects associated with recurrent genomic aberrations likely represent a relevant source of CLL-specific selecting antigens.

Effects of ibrutinib on T-cell immunity in patients with chronic lymphocytic leukemia

Chronic lymphocytic leukemia (CLL), a highly heterogeneous B-cell malignancy, is characterized by tumor microenvironment disorder and T-cell immune dysfunction, which play a major role in the proliferation and survival of CLL cells. Ibrutinib is the first irreversible inhibitor of Bruton’s tyrosine kinase (BTK). In addition to targeting B-cell receptor (BCR) signaling to kill tumor cells, increasing evidence has suggested that ibrutinib regulates the tumor microenvironment and T-cell immunity in a direct and indirect manner. For example, ibrutinib not only reverses the tumor microenvironment by blocking cytokine networks and toll-like receptor signaling but also regulates T cells in number, subset distribution, T-cell receptor (TCR) repertoire and immune function by inhibiting interleukin-2 inducible T-cell kinase (ITK) and reducing the expression of inhibitory receptors, and so on. In this review, we summarize the current evidence for the effects of ibrutinib on the tumor microenvironment and cellular immunity of patients with CLL, particularly for the behavior and function of T cells, explore its potential mechanisms, and provide a basis for the clinical benefits of long-term ibrutinib treatment and combined therapy based on T-cell-based immunotherapies.

Phase 1 TRANSCEND CLL 004 study of lisocabtagene maraleucel in patients with relapsed/refractory CLL or SLL

Bruton tyrosine kinase inhibitors (BTKi) and venetoclax are currently used to treat newly diagnosed and relapsed/refractory chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL). However, most patients eventually develop resistance to these therapies, underscoring the need for effective new therapies. We report results of the phase 1 dose-escalation portion of the multicenter, open-label, phase 1/2 TRANSCEND CLL 004 (NCT03331198) study of lisocabtagene maraleucel (liso-cel), an autologous CD19-directed chimeric antigen receptor (CAR) T-cell therapy, in patients with relapsed/refractory CLL/SLL. Patients with standard- or high-risk features treated with ≥3 or ≥2 prior therapies, respectively, including a BTKi, received liso-cel at 1 of 2 dose levels (50 × 106 or 100 × 106 CAR+ T cells). Primary objectives included safety and determining recommended dose; antitumor activity by 2018 International Workshop on CLL guidelines was exploratory. Minimal residual disease (MRD) was assessed in blood and marrow. Twenty-three of 25 enrolled patients received liso-cel and were evaluable for safety. Patients had a median of 4 (range, 2-11) prior therapies (100% had ibrutinib; 65% had venetoclax) and 83% had high-risk features including mutated TP53 and del(17p). Seventy-four percent of patients had cytokine release syndrome (9% grade 3) and 39% had neurological events (22% grade 3/4). Of 22 efficacy-evaluable patients, 82% and 45% achieved overall and complete responses, respectively. Of 20 MRD-evaluable patients, 75% and 65% achieved undetectable MRD in blood and marrow, respectively. Safety and efficacy were similar between dose levels. The phase 2 portion of the study is ongoing at 100 × 106 CAR+ T cells. This trial was registered at clinicaltrials.gov as NCT03331198.

The Mysterious Actor-γδ T Lymphocytes in Chronic Lymphocytic Leukaemia (CLL)

Chronic lymphocytic leukaemia (CLL) is the most common leukaemia among adults. It is the clonal expansion of B cells expressing CD19 and CD5. Despite significant progress in treatment, CLL is still incurable. γδ T cells comprise an important subset of the cytotoxic T cells. Although γδ T cells in CLL are dysfunctional, they still can possibly be used for immunotherapy. The current paper reviews our understanding of γδ T lymphocytes in CLL.

Mechanisms of Immunosuppressive Tumor Evasion: Focus on Acute Lymphoblastic Leukemia

Acute lymphoblastic leukemia (ALL) is a malignancy with high heterogeneity in its biological features and treatments. Although the overall survival (OS) of patients with ALL has recently improved considerably, owing to the application of conventional chemo-therapeutic agents, approximately 20% of the pediatric cases and 40-50% of the adult patients relapse during and after the treatment period. The potential mechanisms that cause relapse involve clonal evolution, innate and acquired chemoresistance, and the ability of ALL cells to escape the immune-suppressive tumor response. Currently, immunotherapy in combination with conventional treatment is used to enhance the immune response against tumor cells, thereby significantly improving the OS in patients with ALL. Therefore, understanding the mechanisms of immune evasion by leukemia cells could be useful for developing novel therapeutic strategies.