Therapeutic antibodies against ROR-1 protein and methods for use of same

#The Sequence Listing written in file 048537-556C05US_SEQUENCE_LISTING_ST25.TXT, created December 21, 44,223 bytes, machine format IBM-PC, MS-Windows operating system, is hereby incorporated by reference.

#Tyrosine kinases are important mediators of the signaling cascade, determining key roles in diverse biological processes like growth, differentiation, metabolism and apoptosis in response to external and internal stimuli. Studies have implicated the role of tyrosine kinases in the pathophysiology of cancer. Schlessinger J. (2000) Cell, 103:211-225; and Robinson et al. (2000) Oncogene, 19:5548-5557. MacKeigan and colleagues used a large-scale RNAi approach to identify kinases that might regulate survival and apoptosis of a human tumor cell line (HeLa), RNAi to ROR1 was found as one of the most potent in inducing apoptosis among the set of RNAi targeting each of 73 different kinase-encoding genes. MacKeigan et al. (2005) Nat Cell Biol., 7:591-600. However, these investigators did not examine the expression or function of ROR1 protein in these cells.

#ROR1, receptor tyrosine kinase like orphan receptor one, is a molecule expressed at high levels during embryogenesis that plays a major role in the development of the skeleton, lungs and nervous system. ROR1 expression is greatly decreased in postpartum mammalian cells to levels that are barely detectable. ROR1 is a membrane-receptor with an intracellular kinase-like domain and extracellular Frizzled-like cysteine-rich domain, which is common to receptors of members of the Wnt-family. ROR1 is member of the ROR family that is evolutionarily conserved among Caenorhavditis elegans, Drosophila, mice and humans. Wilson C, Goberdhan D C, Steller H. Dror, a potential neurotrophic receptor gene, encodes a Drosophila homolog of the vertebrate Ror family of Trk-related receptor tyrosine kinases. Proc Natl Acad Sci USA. 1993; 90:7109-7113; Oishi et al. (1997) J Biol Chem., 272:11916-11923; Masiakowski et al. (1992) J Biol Chem., 267:26181-26190; Forrester et al. (2002) Cell Mol Life Sci., 59:83-96; and Oishi et al. (1999) Genes Cells, 4:41-56. The actual functional role of the ROR1 protein during embryogenesis is unknown, although it is believed to be a receptor for Wnt proteins that regulate cellular polarity and cell-to-cell interactions.

#FIG. 1 is a series of graphs illustrating the results of flow cytometric analysis of the expansion of CD5+B220low leukemia B cells in ROR1 Tg mice following the adoptive transfer of 1×107 splenocytes from a ROR1×TCL1 Tg mouse. Upper panel depicts the expansion from 2 to 4 weeks following adoptive transfer. Percentage of leukemic cells on the contour plot of mCD5 (x-axis) vs mB220 (y-axis) is indicated on above the gate on CD5+B220low lymphocytes. Bottom panel depicts the relative ROR1 expression (x axis) using the mouse anti-ROR1 4A5 mAb.

#FIG. 2 is a diagram outlining the analysis of anti-ROR1 mAb on the adoptive transfer and engragment of ROR1×TCL1 leukemic splenocytes. ROR1 Tg mice (4 mice/group) were given 250 ug of 4A5, D10 or control mIgG i.v. on day 0. The following day, 1×107 splenocytes from a ROR1×TCL1 Tg mouse were adoptively transferred i.v. All mice were subsequently monitor weekly for expansion of CD5+B220low leukemic B cells by flow cytometry beginning at 2 weeks post transfer.

#FIG. 3 is a series of graphs illustrating the results of a flow cytometric analysis which demonstrate that anti-ROR1 antibodies of the invention inhibited the development of CLL-like leukemia in ROR1 Tg mice. 2 weeks after adoptive transfer, the PBMC facs analysis were performed. The data showed the anti-ROR1 antibody D10 but not anti-ROR1 antibody 4A5 could markedly inhibit the CD5dullB220+ and ROR1brightB220+ leukemic B cell expansion.

#The presently disclosed subject matter are described more fully below. However, the presently disclosed subject matter may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Indeed, many modifications and other embodiments of the presently disclosed subject matter set forth herein will come to mind to one skilled in the art to which the presently disclosed subject matter pertains having the benefit of the teachings presented in the foregoing descriptions and the associated FIGS. Therefore, it is to be understood that the presently disclosed subject matter is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.

#Antibodies of the invention were produced monoclonally using techniques as previously described. Briefly, Naturally occurring antibodies are generally tetramers containing two light chains and two heavy chains. Experimentally, antibodies can be cleaved with the proteolytic enzyme papain, which causes each of the heavy chains to break, producing three separate subunits. The two units that consist of a light chain and a fragment of the heavy chain approximately equal in mass to the light chain are called the Fab fragments (i.e., the antigen binding fragments). The third unit, consisting of two equal segments of the heavy chain, is called the Fc fragment. The Fc fragment is typically not involved in antigen-antibody binding, but is important in later processes involved in ridding the body of the antigen.

#Because Fab and F(ab′)2 fragments are smaller than intact antibody molecules, more antigen-binding domains are available than when whole antibody molecules are used. Proteolytic cleavage of a typical IgG molecule with papain is known to produce two separate antigen binding fragments called Fab fragments which contain an intact light chain linked to an amino terminal portion of the contiguous heavy chain via by disulfide linkage. The remaining portion of the papain-digested immunoglobin molecule is known as the Fc fragment and consists of the carboxy terminal portions of the antibody left intact and linked together via disulfide bonds. If an antibody is digested with pepsin, a fragment known as an F(ab′)2 fragment is produced which lacks the Fc region but contains both antigen-binding domains held together by disulfide bonds between contiguous light and heavy chains (as Fab fragments) and also disulfide linkages between the remaining portions of the contiguous heavy chains (Handbook of Experimental Immunology. Vol 1: Immunochemistry, Weir, D. M., Editor, Blackwell Scientific Publications, Oxford (1986)).