Therapeutic targeting of CD19 in hematological malignancies: past, present, future and beyond.

Abstract During the past few decades, CD19 has been at the center of various scientific/translational endeavors to develop targeted therapeutics against B-cell malignancies. Due to the expression pattern of CD19 throughout the B-cell lineage, and on most B-cell malignancies, it became a preferred target for the development of experimental therapeutic agents during the first years of the monoclonal antibodies era. Successful preclinical experiments led to the first generation of clinical trials, based predominantly on toxin/anti-CD19 murine immunoconjugates. These, however, mostly failed due to poor biochemical design of the reagents, and the generation of human anti-murine antibodies. Modern anti-CD19 reagents are based on humanized anti-CD19 antibodies designed to attract components of the immune system, predominantly T-cells, to eliminate CD19+ target cells. These include, for example, modified anti-CD19 antibodies, and bispecific anti-CD19/CD3 antibodies. One of the most attractive approaches to target malignant B-cells is based on the introduction of chimeric antigen receptors (CARs) into patient derived T-cells. CARs are composed of extracellular recognition sequences derived from anti-CD19 antibodies, and intracellular signaling components that can foster T-cell activation. The novel anti-B-cell therapeutics have shown promising clinical effects against various B-cell malignancies, including acute lymphoblastic leukemia (ALL), chronic lymphocytic leukemia (CLL) and non-Hodgkin lymphoma (NHL), although expected side effects (e.g. significant immunosuppression) were also recorded. These novel successful anti-CD19 agents may have the potential to be used in other fields, such as autoimmunity.

Insect-bite-like reaction in patients with chronic lymphocytic leukemia: a study from the Israeli Chronic Lymphocytic Leukemia Study Group.

An insect-bite-like reaction is known to occur in patients with chronic lymphocytic leukemia (CLL). Most of the literature, however, consists of isolated case reports or small case series. The aim of this retrospective study was to review the national experience with insect-bite-like reaction in a large group of patients with CLL. The study cohort of patients with these skin reactions consisted of 48 patients (25 males, 23 females) of mean age 64.8 yr (range 33-89) at skin eruption. Data on clinical, histologic, immunophenotypic, and cytogenetic characteristics, treatment, and outcome were collected from the medical files. Mean time between diagnosis of CLL and appearance of the skin lesions was 3.1 yr (range -4 to 14 yr). The eruption was not related to disease activity or the course of the hematological disease. The eruption preceded the diagnosis of CLL in 10 patients (by 0-4 yr); and followed the diagnosis in 36; in 11 patients, it occurred during therapy for CLL and in nine after therapy. Mean duration of the skin findings was 21.5 months (range 0.3-132). The eruption usually presented in summer, although it occurred also at other times of the year, and predominantly affected the upper and lower limbs, although it also appeared on unexposed areas. Treatment included local ointments, antihistaminics, oral steroids, antibiotics, phototherapy, and dapsone with varying responses. Insect-bite-like reactions is a relatively common and disturbing skin reaction in CLL patients, it may be related to the immune dysregulation accompanying CLL and further exacerbated by external factors, including actual insect bites, chemoimmunotherapy, and pyogenic infection.