TRAIL-R2-specific antibodies and recombinant TRAIL can synergise to kill cancer cells

Abstract

TRAIL induces apoptosis in cancer cells whilst sparing normal tissues. Despite promising pre-clinical results, few patients responded to treatment with recombinant TRAIL (Apo2L/Dulanermin) or TRAIL-R2-specific antibodies, such as conatumumab (AMG655). It is unknown whether this was due to intrinsic TRAIL resistance within primary human cancers or insufficient agonistic activity of the TRAIL-R-targeting drugs. FcγR-mediated crosslinking increases the cancer-cell-killing activity of TRAIL-R2-specific antibodies in vivo. We tested this phenomenon using FcγR-expressing immune cells from patients with ovarian cancer. However, even in the presence of high numbers of FcγR-expressing immune cells, as found in ovarian cancer ascites, AMG655-induced apoptosis was not enabled to any significant degree, indicating that this concept may not translate into clinical use. On the basis of these results we next set out to determine whether AMG655 possibly interferes with apoptosis induction by endogenous TRAIL which could be expressed by immune cells. To do so, we tested how AMG655 affected apoptosis induction by recombinant TRAIL. This, however, resulted in the surprising discovery of a striking synergy between AMG655 and non-tagged TRAIL (Apo2L/TRAIL) in killing cancer cells. This combination was as effective in killing cancer cells as highly active recombinant isoleucine-zipper-tagged TRAIL (iz-TRAIL). The increased killing efficiency was due to enhanced formation of the TRAIL death-inducing signalling complex (DISC), enabled by concomitant binding of Apo2L/TRAIL and AMG655 to TRAIL-R2. The synergy of AMG655 with Apo2L/TRAIL extended to primary ovarian cancer cells and was further enhanced by combination with the proteasome inhibitor bortezomib or a SMAC mimetic. Importantly, primary human hepatocytes were not killed by the AMG655-Apo2L/TRAIL combination, also not when further combined with bortezomib or a SMAC mimetic. We therefore propose that clinical-grade non-tagged recombinant forms of TRAIL, such as dulanermin, could be combined with antibodies such as AMG655 to introduce a highly active TRAIL-R2-agonistic therapy into the cancer clinic.

Liposome-bound TRAIL induces superior DR5 clustering and enhanced DISC recruitment in histiocytic lymphoma U937 cells

“…Interestingly, the co-administration of LUV-TRAIL and DJR2 did not enhance apoptosis induction, suggesting that there was a maximum threshold of pro-apoptotic signaling to be achieved by DR5 clustering, and this was already reached with LUV-TRAIL alone. In this regard, it has been recently showed that combination of TRAIL with DR5-specific antibodies can synergize to kill cancer cells [24]. In that study, the authors concluded that simultaneous binding of both TRAIL and agonistic antibodies to death receptors resulted in enhanced DR5 cross-linking, causing an increased DISC recruitment, similar to our results.…”

“…We achieved this by pre-incubating the cells with monoclonal specific DR4 and/or DR5 antibodies similar to the work recently described by Tuthill et al [24]. As shown in Fig.…”

Structural principles of tumor necrosis factor superfamily signaling

“…However, more recent studies have found that the combination of DR5-specific antibodies and hrTRAIL can synergize to kill cancer cells both in vitro (70,71) and in vivo (70). This combination therapy proved beneficial even in some previously TRAIL-resistant cancers.…”

TNF-Related Apoptosis-Inducing Ligand (TRAIL)–Armed Exosomes Deliver Proapoptotic Signals to Tumor Site

“…This could be attributed to the different sensitivity of tumors to TRAIL on one hand and to the limited activity of targeting molecules, due to the short half-life of recombinant TRAIL and the monospecificity of the agonistic antibodies (Abs), on the other (1,5). To ameliorate TRAIL activity, several formulations of recombinant TRAIL, such as fusion to poly-histidine, Flag and leucin Zipper tags, or linked to Fc portion of IgG, have been developed and are currently tested at preclinical level (6,7). The combination of recombinant TRAIL with chemotherapeutics, radiotherapy, small molecules, or natural compounds aimed at enhancing the sensitivity of cancer cells, have also found wide application in preclinical approaches (8,9).…”