LBY135, a novel anti‐DR5 agonistic antibody induces tumor cell–specific cytotoxic activity in human colon tumor cell lines and xenografts

Abstract

TRAIL (TNF-related apoptosis-inducing ligand) induces apoptosis on binding to DR4 and DR5 receptors on the surface of tumor cells. These receptors are of particular interest in the development of cancer therapeutics as they preferentially mediate tumor cell apoptosis. We have generated a chimeric anti-DR5 agonistic antibody, LBY135, from its murine parental antibody, LCR211, identified using hybridoma technology. Both LCR211 and LBY135 specifically bind to DR5 with nanomolar affinity, mimic TRAIL to induce cell death in tumor cells, and have little effect on non-transformed cells in vitro. The anti-DR5 antibody reduced viability in 45% of a panel of 40 human colon cancer cell lines with IC 50 values of 20 nM or less. In vivo, using human colorectal tumor xenograft mouse models, LCR211 induced tumor regression and showed enhanced efficacy when combined with 5-FU. Both in vitro evaluation of ADCC (antibody-dependent cell-mediated cytotoxicity) and CDC (complement-dependent cytotoxicity), and in vivo studies using a non-functional DR5 specific antibody or SCID-Beige mice, suggested ADCC and CDC are unlikely to be the mechanism to ablate tumors in vivo. LBY135 and LCR211 appear to mediate cell death and tumor regression mainly through apoptosis, as demonstrated by the activation of caspase 3, caspase 8, M30, and TUNEL assay. In addition, the discovery of synergy between cross-linked LBY135 and TRAIL not only revealed the unique epitope of LBY135, but also demonstrated an additional mechanism of action for LBY135 in vivo. LBY135 demonstrates promise as a novel therapeutic for cancer treatment and is currently in Phase I clinical trials. Drug Dev Res 69: 69-82, 2008.

Multivalent Scaffold Proteins as Superagonists of TRAIL Receptor 2–Induced Apoptosis

“…However, IgG molecules are bivalent, and as shown in this study, higher valencies and nonantibody molecular formats can lead to vastly superior activation of TRAILR2-mediated apoptosis. This explains why some agonistic antibodies against TRAILR2 show low or no in vitro activity in the absence of higher-order cross-linking and are less active than soluble TRAIL trimer (7,38,39). Despite the fact that such antibodies have lower valency, they can exhibit antitumor activity in murine xenograft studies (7,8,39).…”

“…This explains why some agonistic antibodies against TRAILR2 show low or no in vitro activity in the absence of higher-order cross-linking and are less active than soluble TRAIL trimer (7,38,39). Despite the fact that such antibodies have lower valency, they can exhibit antitumor activity in murine xenograft studies (7,8,39). A recent study with drozitumab, an agonistic TRAILR2 mAb, showed that binding to Fcg receptors was essential to the antitumor activity in mice (10).…”

Imaging Caspase-3 Activation as a Marker of Apoptosis-Targeted Treatment Response in Cancer

“…dose of M413 (based on internal pilot studies) or 6 hrs after the last of three 200 μg i.p. doses of LCR211 administered as previously described [30]. …”

TRAIL receptor signaling and therapeutics

“…Since the in-vivo anti-tumor activity of LBY135 has been verified in human colorectal xenograft models in mice [94], Novartis is recruiting patients for an open-label, multi-center, twoarm Phase I/II trial of LBY135 alone and in combination with capecitabine in advanced solid tumors (Nevada Cancer Institute, Las Vegas, NV, USA) [95]. Leukemia [101] TRAIL-R1 HDAC inhibitors Enables transcription by blocking gene acetylation Leukemia [102] TRAIL-R2 HDAC inhibitors Histone deacetylase inihbition Malignant tumor cells [103] TRAIL-R2 Proteasome inhibitors Inhibits protein degradation Prostate [104], colon [105], lung [106] TRAIL-R2 Radiotherapy Induction of DNA damage Prostate [106], leukemia [107], breast, lung, colon [108] TRAIL-R2 NSAIDs Inhibition of COX-1 and 2 Colon [109], lung [110], prostate and colon [111] TRAIL-R1 and TRAIL-R2 Proteasome inhibitors Inhibits protein degradation Leukemia [112] TRAIL-R1 and TRAIL-R2 HDAC inhibitors Enables transcription by blocking gene deacetylation…”