Immunotherapy of recurrent B-cell malignancies after allo-SCT with Bi20 (FBTA05), a trifunctional anti-CD3 x anti-CD20 antibody and donor lymphocyte infusion.

Donor lymphocyte infusions (DLIs) after allo-SCT displayed limited use in CLL and highly malignant non-Hodgkin's lymphoma (NHL). Here we studied whether Bi20 (FBTA05), a novel trifunctional bispecific antibody targeting CD20 on lymphoma cells and CD3 on T cells, could induce GVL responses in combination with DLI or mobilized PBSCT after allogeneic transplantation in these diseases. Six patients (three cases with p53-mutated CLL and three with high-grade NHL (HG-NHL)) refractory to standard therapy were treated with escalating doses of Bi20 (range 10-2000 microg) followed by DLI or SCT. Thereby, all CLL patients showed a prompt but transient clinical and hematological response. In one patient with HG-NHL, we observed a halt in progression for almost 4 months. Side effects (fever, chills and bone pain) were tolerable and appeared at antibody dose levels between 40 and 200 microg. The cytokine profile was characterized by transient increases of IL-6, IL-8 and IL-10. Neither human anti-mouse antibodies nor GVHD developed, allowing repeated treatment courses. In summary, the trifunctional antibody Bi20 induced prompt antitumor responses in extensively pretreated, p53-mutated alemtuzumab and rituximab refractory patients indicating its therapeutic potential.

The interaction of the Bcr-Abl tyrosine kinase with the Src kinase Hck is mediated by multiple binding domains.

Bcr-Abl is found in more than 95% of cases with CML. The mechanism of Bcr-Abl-induced transformation is not fully understood. Bcr-Abl is a constitutively active tyrosine kinase with transforming capacity for hematopoietic cells. We demonstrated recently that the Src kinase Hck interacts directly with Bcr-Abl by a kinase-independent mechanism. Moreover, the inhibition of the Hck kinase seems to block some of the transforming effects of Bcr-Abl. To identify the binding domains mediating this interaction of Hck with Bcr-Abl, we co-expressed different plasmid and baculovirus vectors containing mutants or single domains of Bcr-Abl and/or Hck in COS7 and Sf9 cells. At least four independent binding regions for Hck were identified in Bcr-Abl, one in Bcr, one in the region comprising the SH3 and SH2 domain of Abl, one in the SH1 domain of Abl, and one in the C-terminal domain of Abl. In the Hck kinase, deletion of the SH2 and/or the SH3 region abolished binding to Bcr-Abl. In contrast, deletion of the Hck SH1 domain enhanced binding of Hck to Abl and Bcr-Abl. In conclusion, the results indicate that the interaction of Bcr-Abl with Hck is mediated by a novel, complex mechanism that involves multiple domains of Bcr-Abl and the SH2 and SH3 domains of Hck.

Cloning, sequence determination and functional expression of the genes encoding adenovirus type-4 polymerase and the terminal protein precursor.

Sequences of the open reading frames encoding adenovirus type 4 (Ad4) DNA polymerase and the terminal protein precursor were determined. Sequence comparisons with the corresponding genes and proteins from Ad2 and Ad5 show high overall identity, but significant differences in those portions of the two proteins thought to be essential for their biological activities. Both Ad4 proteins were functionally expressed in insect cells from the corresponding cDNAs.