Comparative genomics and receptor signaling in MBL and CLL arising in siblings

Chronic lymphocytic leukemia (CLL) is a monoclonal expansion of functionally
incompetent B lymphocytes with a distinct phenotype. CLL amounts to 16.5 % of
all newly diagnosed lymphomas and has the highest prevalence of all hematologic
tumors. 30-40% of CLL patients will die of their disease, and CLL remains
incurable with conventional therapy. Therefore, novel treatments are required
to improve the outcome of CLL, but their development is hampered by the fact
that the etiology of CLL has remained elusive.
Monoclonal B-cell lymphocytosis (MBL) is a clonal expansion of B cells of
mostly CLL phenotype but without fulfilling diagnostic CLL criteria. The
prevalence of MBL in adults is 2-6% and in relatives of CLL patients 14-18%.
15-20% of MBL eventually progress to CLL.

This project aims to achieve advances in understanding CLL initiation and
progression, and to identify novel targets for therapy of CLL, through a
detailed genetic and immunological comparison of manifest CLL and MBL as the
premalignant counterpart.

Screening for MBL in siblings of CLL patients is performed by standardized
four-color flow cytometry.
In the first work package, the B-cell receptor (BCR) expressed by CLL and MBL
cells is being amplified by PCR and cloned.
The signaling properties of CLL and MBL BCR are tested for antigen-independent,
autonomous signaling in murine pre-B cells deficient in Rag2, Vlambda5, and
BLNK (SLP-65).

The second work package aims to identify genetic aberrations in MBL with the
highest possible resolution by whole exome sequencing and SNP microarrays.
Restriction of this analysis to CLL and MBL arising in siblings will reduce
irrelevant genetic differences such as copy number variations that exist
between nonrelated individuals as much as possible. We anticipate that some
identifiable genetic aberrations are associated with the premalignant MBL
state, including some CLL-associated genetic aberrations, but that an
individual MBL will carry less genetic changes than an average CLL. Identified
genetic changes will be validated on an existing cohort of 250 CLL cases.

The aim of the project is to deduce an integrated and hierarchical model of CLL
etiology by ranking genetic and signaling events as obtained from both work
packages. This model will perform an instrumental role in developing rational,
biology-based approaches to prevent CLL progression and to control the
established malignancy.

A single venapuncture to collect a blood sample of 45 ml. The risk for
deleterious side effects is negligible.