CD27, a TNF receptor family member was identified as a membrane molecule on human T cells (van Lier et al., 1987, J Immunol 139:1589-96). According to current evidence, CD27 has a single ligand, CD70, which is also a TNF family member (Goodwin et al., 1993, Cell 73:447-56). CD27 and CD70 have also been identified and cloned in the mouse system (Gravestein et al., 1993, Eur J Immunol 23:943-50; Tesselaar et al., J Immunol 159:4959-65).
CD27 is exclusively expressed by hematopoietic cells, in particular those of the lymphocyte lineage, i.e. T-, B- and NK cells. In the human system, CD27 expression in the αβ T cell lineage is induced during positive selection of thymocytes and maintained in naive conventional CD4+ and CD8+ T cells (Vanhecke et al., 1997, J Immunol 159:5973-83). Upon T cell activation via the T cell antigen receptor (TCR), CD27 expression increases, in a transient manner (van Lier et al., 1987, J Immunol 139:1589-96). Next, CD27 is shed from the surface of activated T cells and the soluble form of CD27 can be detected in the serum marker for (chronic) T cell activation (Hintzen et al., 1991, J Immunol 147:29-35). Among peripheral T cells, permanent loss of CD27 expression results from persistent antigenic stimulation and hallmarks terminally differentiated effector/memory T cells, while central memory T cells maintain CD27 (Baars et al., 1995, J Immunol 154:17-25; Hamann et al., 1997, J Exp Med 186:1407-18). CD27 is also expressed on human γδ T cells and induced during thymic development (Offner F et al, 1997, J Immunol 158:4634-41). Moreover, loss of CD27 expression is a hallmark of chronically stimulated γδ T cells (Gioia C et al., 2002, J Immunol 168:1484-9). Generally, CD27 is an exquisite marker for cellular activation and differentiation stages and used as such in human clinical diagnostics and research.
In the mouse, CD27 was found on hematopoietic stem cells, multipotent progenitors and common lymphoid precursors (Medina et al., 2001, Nat Immunol 2:718-24; Wiesmann et al., 2000, Immunity 12:193-9).
CD27 was originally defined as a human T-cell co-stimulatory molecule that increments the proliferative response to TCR stimulation (van Lier et al., 1987, J Immunol 139:1589-96). Presence of CD70 dictates the timing and persistence of CD27-mediated co-stimulation. Upon immune activation, dendritic cells, T-, B- and NK cells transiently express CD70, contingent upon the presence of antigen, Toll-like receptor agonists or inflammatory cytokines.
CD27 stimulation using anti-CD27 mAb CLB-CD27/1 (9F4) incremented the proliferative response of human T cells to TCR stimulation (Van Lier et al., 1987, J Immunol 139:1589-96). This was confirmed using crosslinked anti-CD27 mAb 1A4, or transfectants expressing CD70. Conversely, antibodies directed to CD27 or CD70 could block this proliferation. Both CD4+ and CD8+ T cells responded to CD27 co-stimulation (Goodwin et al., 1993, Cell 73:447-56; Kobata et al., 1994, J Immunol 153:5422-32; Hintzen et al., 1995, J Immunol 154:2612-23). Studies in mice unambiguously support the role of CD27 as a co-stimulatory receptor for naive CD8+ and CD4+ αβ T cells. For mouse T cells, CD27 primarily promotes their survival upon TCR-mediated activation, but in human T cells, it additionally promotes cell cycle entry and/or activity (reviewed in Borst et al., 2005, Curr Op Immunol 17:275-281; Nolte et al., 2009, Immunol Rev 229:216-231).
Upon its transient engagement as occurs in acute infections that temporarily upregulate CD70, CD27 supports the generation of a CD8+ effector T cell pool in priming organs, its maintenance at the tissue effector site, its conversion into memory cells and its potential to exercise memory function (Hendriks et al., 2003, J Exp Med 198:1369-1380; Hendriks et al. 2005, J Immunol 175:1666-75, Xiao et al, 2008, J Immunol 181:1071-82). Studies with CD70 blocking antibody in mouse models support the concept that CD27-CD70 interactions can make an important contribution to generation of CD8+ effector T cells, e.g. after protein immunization, virus infection and allotransplantation (Taraban et al., 2004, J Immunol 173:6542-46; Bullock and Yagita, 2005, J Immunol 174:710-17; Yamada et al., 2005, J Immunol 174:1357-1364; Schildknecht et al., 2007, Eur J Immunol 37:716-28).
Transgenic expression of CD70 in immature dendritic cells sufficed to convert immunological tolerance to virus or tumors into CD8+ T cell responsiveness upon immunization with MHC class I-restricted peptide in PBS. Likewise, agonistic soluble CD70 promoted the CD8+ T cell response upon such peptide immunization (Rowley et al., 2004, J Immunol 172:6039-6046) and in CD70 transgenic mice, CD+ and CD8+ effector cell formation in response to TCR stimulation was greatly facilitated (Arens et al. 2001, Immunity 15:801-12; Tesselaar et al., 2003, Nat Immunol 4:49-54; Keller et al. 2008, Immunity 29:334-346). In mouse lymphoma models, tumor rejection was improved upon CD70 transgenesis or injection of an activating anti-mouse CD27 antibody (Arens et al., 2003, J Exp Med 199:1595-1605; French et al., 2007, Blood 109:4810-15; Sakanishi and Yagita, 2010, Biochem. Biophys. Res. Comm. 393:829-835; WO 2008/051424).
Generally, CD27 expression on lymphoid cells is associated with survival potential. Salient examples come from human adoptive T cell therapies, in cancer and AIDS patients, where long-term persisting T cells were selected for CD27 expression. In addition, CD70 expression on tumor-infiltrating lymphocytes was positively correlated with an anti-tumor immune response, potentially reflecting effector T cell survival within the tumor (Ochsenbein et al., 2004, J Exp Med 200:1407-17; Huang et al., 2006, J Immunol 176:7726-35).
For conventional CD+ T cells, CD27 similarly promotes primary and secondary responses (Hendriks et al., 2000, Nat Immunol 1:433-40; Xiao et al, 2008, J Immunol 181:1071-82). Moreover, CD27 co-stimulation favours an IL-12 independent pathway for T helper-1 development and enables CD+ T cells to provide help for memory programming of CD8+ T cells (Soares et al., 2007, J Exp Med 204:1095-106; Xiao et al, 2008, J Immunol 181:1071-8). In C57BL/6 mice, CD27 stimulation is consistently associated with Th1-type CD+ T cell differentiation (Arens et al. 2001, Immunity 15:801-12; Soares et al., 2007, J Exp Med 204:1095-106; Xiao et al, 2008, J Immunol 181:1071-82) and in human CD+ T cells in vitro, CD27 promoted Th1 development in presence of IL-12, but had no differentiation-inducing effect in presence of IL-4 (van Oosterwijk et al., 2007, Int Immunol 19:713-18).
In addition, CD27 stimulation was demonstrated to promote human regulatory T cell generation and/or function (Jacquot et al., 1997, Cell Immunol 179:48-54). Amongst natural regulatory T cells in human, high CD27 expression hallmarks the cells that have the highest suppressive activity and the CD27 high subpopulation is preferentially amplified during rapamycin treatment (Koenen et al., 2005, J Immunol 174:7573-83; Coenen et al., 2006, Blood 107:1018-23). Recent observations suggest that the CD27+ Treg subpopulation can differentiate into Th17 cells (Koenen et al., 2008, Blood 112:2340-52). Interestingly, CD70+ B lymphoma cells were found to stimulate Treg formation and impede Th17 differentiation by CD27 triggering on intratumoral T cells (Yang et al., 2007, Blood 110:2537-44; Yang et al., 2009, Cancer Res 69:5522-30).
In resting B cells, CD27 expression 1s absent, but it is induced during B cell activation in germinal centers and in human, it is subsequently maintained on memory B cells and plasma cells (Agematsu et al., 2000 Immunol Today 21:204-206; Jung et al., 2000, Eur J Immunol 30:2437-2443). CD27 also acts as a co-stimulatory receptor on B cells. In in vitro systems with human B cells, CD27-CD70 interactions consistently stimulate Ig secretion (Agematsu et al., 1997, Eur J Immunol 27:2073-79; Jacquot et al., 1997, J Immunol 159:2652-7).
Human NK cells can be subdivided into two functional subsets based on CD27 expression with lack of CD27 expression identifying the mature effector cells (Sugita et al., 1992, J Immunol 149:1199-203; Vossen et al., 2008, J Immunol 180:3739-45). Data suggest a similar co-stimulatory role for CD27 in NK cells as for T-cells (Takeda et al., 2000, J Immunol 164; 1741-1745). The functional effect of CD27 activation on NK cells was established by increased NK mediated killing of CD70-expressing tumor cells. CD27-mediated NK cell activation also promoted the generation of CD8+ anti-tumor immunity (Aulwurm et al., 2006, Int J Cancer 11S:1728-1735; Kelly et al., 2002, Nat Immunol 3:83-90). Recently, NKT cells were shown to promote CD8+ T cell immunity by induction of CD70 on dendritic cells (Taraban et al., 2008, J Immunol 139:1589-96).
In addition, CD27 is highly expressed on tumor cells derived from non-Hodgkin's lymphomas and chronic lymphocytic leukemias (Ranheim et al., 1995, Blood 85:3556-3565; van Oers et al., 1993, Blood 82:3430-3436). Soluble CD27 is used as a serum marker for lymphoid malignancy (Van Oers et al., 1993, Blood 82:3430-6).
In the research that led to the present invention it was found that the hCD27.15 mAb stimulates the proliferation and/or survival of CD27+ cells. Enhanced proliferation and/or survival of CD27+ cells forms the basis of different therapeutic uses. Monoclonal antibodies that activate CD27 are known. Two activating anti-human CD27 antibodies have been described (Van Lier et al., 1987, J. Immunol. 1987, 139:1589-96; Kobata et al., 1994, J. Immunol. 153:5422-5432). In addition, activating anti-mouse CD27 antibodies have been described (French et al., 2007, Blood 109:4810-15; WO 2008/051424; Sakanishi and Yagita, 2010, Biochem. Biophys. Res. Comm. 393:829-835). hCD27.15 is a unique anti-human antibody, which is, in contrast to 1A4 and 9F4 able to activate human CD27 more effectively than its ligand CD70. These characteristics of hCD27.15 result in a significantly increased effect on proliferation of CD8+ and CD+ T-cells as compared to 1A4, 9F4 and Fc-CD70. Administration of hCD27.15 alone or in combination with other agents to a human being can for example be used in the treatment of cancer.
Citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.