The Immunology of Chronic Lymphocytic Leukemia Megan S. Lim MD PhD Professor Director of Division of Hematopathology (HUP/CHOP) Director of Lymphoma Biology Program ASCLS Annual Meeting August 3, 2016 Outline 1. Clinical aspects and definitions 2. Molecular pathogenesis of CLL 3. Impact of genetics on immunobiology of CLL 4. CLL and tumor microenvironment 5. Current therapies for CLL (1) (2) Clinical Aspects of blood Bone marrow Lymph node (3) (4) definition (WHO 2008) Morphology 1 Morphology 2 Immunophenotype Monomorphic small, round to slightly irregular B lymphocytes Admixed with prolymphocytes and paraimmunoblasts forming proliferation centers in tissue infiltrates CD5+ CD23+ Bone marrow blood Lymph node Tissue Involvement blood, bone marrow, spleen and lymph nodes (5) 1 (6)
CLL CLL Absolute lymphocytosis: > 5x10 9 /L monoclonal lymphocytes (in the absence of extramedullary tissue involvement) Lymphocytosis for at least 3 months Lower lymphocyte count IS allowed in pts with cytopenias or disease related symptoms Autoimmune Thrombocytopenia Hemolytic anemia Bone marrow blood (7) (8) Role of bone marrow examination for CLL Do we need bone marrow examination for diagnosis? No Why still do it? Staging SLL blood: <5x10 9 /L peripheral blood Bone B-cells marrow: no cytopenia Lymph node (9) (10) Most with SLL develop BM involvement and lymphocytosis CLL: peripheral blood blood: <5x10 9 /L peripheral blood B-cells Bone marrow: no cytopenia Lymph node (11) 2 (12)
SLL: morphology Proliferation center Prolymphocytes Pale areas proliferation centers Paraimmunoblasts (13) (14) Immunophenotype Flow cytometric findings in CLL CD20 CD3 CD5 CD23 dim lambda restricted CD5(var)+ CD19+ C20(dim var)+ CD23(dim var)+ CD38+ B cells (15) (16) The cellular origin of chronic lymphocytic leukaemia Molecular pathogenesis of (17) 3 (18) Giulia Fabbri and Riccardo Dalla-Favera, Nature Reviews Cancer 16, 145 162 (2016)
CLL pathobiology: from MBL to Richter syndrome Importance of BCR signaling in CLL (19) Lesley-Ann Sutton, and Richard Rosenquist Haematologica 2015;100:7-16 (20) B cell receptor in CLL and tumor microenvironment (21) Abs produced by CLL are similar to natural autoantibodies AutoAgs and molecular structures related to eliminating apoptosis and pathogenic bacteria may be relevant in triggering the evolution of CLL (22) The tissue microenvironment and CLL Tumor microenvironment in CLL (23) Caligaris-Cappio F, Ghia P JCO 2008;26:4497-4503 4 (24) Giulia Fabbri and Riccardo Dalla-Favera, Nature Reviews Cancer 16, 145 162 (2016)
CLL cell NF-AT Ca++ influx BCL-2 inhibitors CLL cell MAPK (RAF) Fostamatinib Dasatinib Sorafenib The B-cell receptor Anti-CD 19 CARs Anti-CD 19 bi-sp. Abs NFkB MAPKs Rigosertib GS-1101 (CAL-101) Pl3K(δ) Ibrutinib STATs JAKs Akt Pl3K(δ) Chemokine & cytokines TACI BCMA BAFF-R CXCR 4 mtor Akt Perifosine Atacicept Everolimus Immunomodulators (Lenalidomide) BAFF/ APRIL Plerixafor The microenvironment (25) (26) Common Chromosomal Deletions in CLL Impact of genetics on immunobiology of Deletion 13q 14-40% of CLLs (indolent) Deletion 11q 10-32% of CLLs (intermediate) Deletion 17p 3-27% of CLLs (most aggressive) (27) (28) The genetic landscape of chronic lymphocytic leukaemia 17p (7%) 11q (18%) 13q (55%) 12q (16%) NL (18%) (29) NEJM, 2000, 343, 1910-1916 5 (30) Giulia Fabbri and Riccardo Dalla-Favera, Nature Reviews Cancer 16, 145 162 (2016)
Genes with Significant Mutation Frequencies in 91 Patients with Chronic Lymphocytic Leukemia. Associations between Gene Mutations and Clinical Characteristics Wang L et al. N Engl J Med 2011;365:2497-2506. (31) Wang L et al. N Engl J Med 2011;365:2497-2506. (32) Association between recurrent gene mutations and other genetic/immunogenetic features in CLL Pathways involved in CLL initiation, chemoresistance and transformation Lesley-Ann Sutton, and Richard Rosenquist Haematologica 2015;100:7-16 Giulia Fabbri and Riccardo Dalla-Favera, Nature Reviews Cancer 16, 145 162 (2016) (33) (34) prognosis and predictive factors 11q (ATM, SF3B1) 17p (TP53) 12q (CDK4, NOTCH1) 13q (MiRNA, MYD88) NL (18%) Favorable Mutated Ig genes Del13q Poor Unmutated Ig CD38 (>30% considered positive) ZAP70 (>20% considered positive) Del17p, Del11q, Del6q (35) 6 (36)
Biologic Transformation of CLL SLL transformation (Richter transformation) Transformation 2-8% diffuse large B cell lymphoma Original clone <1% Hodgkin lymphoma Unrelated clone (37) (38) /MBL (MBL) Monoclonal B cell lymphocytosis Transformation Neoplastic peripheral blood lymphocyte count < 5 x 10 9 /L Similar immunophenotype as CLL No extramedullary tissue involvement (39) (40) clinical features MBL is detected in 3% of adults Incidence increases with age 0.3% of adults age 18 to 40 years > 5% of individuals over age 60 years 13.5% -18% of first-degree relatives of CLL patients clinical features Incidental flow cytometry finding of peripheral blood M>F Lack symptoms related to bone marrow infiltration, palpable lymphadenopathy, or splenomegaly No autoimmune or infectious process for transient abnormal kappa:lambda ratio (41) 7 (42)
ancillary findings Flow cytometry of peripheral : < 5x10 9 /L Monoclonality Clonal surface kappa or lambda light chain Aberrant phenotype IgH rearrangement (PCR) prognosis 15-34% of patients with MBL (1%-2% per year) eventually progress to CLL Bad prognosis factors A higher monoclonal B-cell count Trisomy 12 or del17p (43) (44) follow-up Current recommendations CBC every 6 to 12 months Repeat flow cytometry assessment of blood over 3 months R/O concurrent plasma cell neoplasm FISH or IG mutation status not indicated key features 1. Most cases are immunophenotypically and genetically similar to CLL and only differ with respect to the peripheral blood clonal cell burden 2. Almost all cases of CLL seem to be preceded by MBL; however, conversely, most patients with MBL have stable disease and never progress to CLL (45) (46) Therapeutic options for CLL Current and future therapies for Standard chemotherapeutic agents (Fludarabine, cyclophosphamide, bendamustine) mabs (Rituximab, Alemtuzumab, Ofatumumab) BCR inhibitors (BTK, PI3K, SYK) Immunomodulating drugs (lenalidomide) Chimeric antigen receptor T cell therapy (47) 8 (48)
Future Directions in CLL Clonal heterogeneity and evolution Mechanism of resistance to targeted therapies Minimal residual disease detection methods Multiparameter flow cytometry High throughput sequencing Novel therapeutic agents (49) 9