The therapeutic mavericks: Potent immunomodulating chaperones capable of treating human diseases.

Two major chaperones, calreticulin (CRT) and binding immunoglobulin protein (GRP78/BiP) dependent on their location, have immunoregulatory or anti-inflammatory functions respectively. CRT induces pro-inflammatory cytokines, dendritic cell (DC) maturation and activates cytotoxic T cells against tumours. By contrast, GRP78/BiP induces anti-inflammatory cytokines, inhibits DC maturation and heightens T-regulatory cell responses. These latter functions rebalance immune homeostasis in inflammatory diseases, such as rheumatoid arthritis. Both chaperones are therapeutically relevant agents acting primarily on monocytes/DCs. Endogenous exposure of CRT on cancer cell surfaces acts as an 'eat-me' signal and facilitates improved elimination of stressed and dying tumour cells by DCs. Therefore, therapeutics that promote endogenous CRT translocation to the cell surface can improve the removal of cancer cells. However, infused recombinant CRT dampens this cancer cell eradication by binding directly to the DCs. Low levels of endogenous BiP appear as a surface biomarker of endoplasmic reticulum (ER) stress in some types of tumour cells, a reflection of cells undergoing proliferation, in which resulting hypoxia and nutrient deprivation perturb ER homeostasis triggering the unfolded protein response, leading to increased expression of GRP78/BiP and altered cellular location. Conversely, infusion of an analogue of GRP78/BiP (IRL201805) can lead to long-term immune resetting and restoration of immune homeostasis. The therapeutic potential of both chaperones relies on them being relocated from their intracellular ER environment. Ongoing clinical trials are employing therapeutic interventions to either enhance endogenous cell surface CRT or infuse IRL201805, thereby triggering several disease-relevant immune responses leading to a beneficial clinical outcome.

Mechanism of action of certolizumab pegol (CDP870): in vitro comparison with other anti-tumor necrosis factor alpha agents.

BACKGROUND: Inhibitors of tumor necrosis factor alpha (TNFalpha) have demonstrated significant efficacy in chronic inflammatory diseases, including Crohn's disease (CD). To further elucidate the mechanisms of action of these agents, we compared the anti-TNFalpha agents certolizumab pegol, infliximab, adalimumab, and etanercept in several in vitro systems. METHODS: The ability of each anti-TNFalpha agent to neutralize soluble and membrane-bound TNFalpha; mediate cytotoxicity, affect apoptosis of activated human peripheral blood lymphocytes and monocytes; induce degranulation of human peripheral blood granulocytes, and modulate lipopolysaccharide (LPS)-induced interleukin (IL)-1beta production by human monocytes was measured in vitro. RESULTS: All 4 agents neutralized soluble TNFalpha and bound to and neutralized membrane TNFalpha. Infliximab and adalimumab were comparable in their ability to mediate complement-dependent cytotoxicity and antibody-dependent cell-mediated cytotoxicity, and to increase the proportion of cells undergoing apoptosis and the level of granulocyte degranulation. Etanercept generally mediated these effects to a lesser degree, while certolizumab pegol gave similar results to the control reagents. LPS-induced IL-1beta production was inhibited by certolizumab pegol, infliximab, and adalimumab, but only partially inhibited by etanercept. CONCLUSIONS: In contrast to the other anti-TNFalpha agents tested, certolizumab pegol did not mediate increased levels of apoptosis in any of the in vitro assays used, suggesting that these mechanisms are not essential for the efficacy of anti-TNFalpha agents in CD. As certolizumab pegol, infliximab, and adalimumab, but not etanercept, almost completely inhibited LPS-induced IL-1beta release from monocytes, inhibition of cytokine production may be important for efficacy of anti-TNFalpha agents in CD.

Preclinical safety evaluation of monoclonal antibodies.

Monoclonal antibodies (mAbs) can be potent and specific therapeutics with long plasma half-lives and therefore long exposure times, which are now being clinically used to treat chronic disorders. Their recombinant design means some of their behaviours in the clinic can be determined at the design stage. However, their specific nature means a flexible approach often is required for preclinical studies and the use of novel approaches including parallel reagents and specific transgenic mice are being used. The key aspects at this level to consider are the effects on safety pharmacology and long-term immune status in the preclinical species used in order to predict to people the likely result of chronic clinical usage.

The use of surrogate antibodies to evaluate the developmental and reproductive toxicity potential of an anti-TNFalpha PEGylated Fab' monoclonal antibody.

Certolizumab pegol (CZP) is a PEGylated Fab' fragment of a humanized monoclonal immunoglobulin G (IgG)1 antibody that binds to human tumor necrosis factor alpha (TNFα) with high affinity. As for many monoclonal antibodies (mAbs), nonclinical safety assessment of CZP has been constrained because of its limited species cross-reactivity and recognition of only nonhuman primate and human TNFα, which presents particular challenges for assessing reproductive and developmental safety. To comprehensively assess the potential liability of TNFα suppression on reproductive and developmental processes, a PEGylated Fab' anti-rat TNFα antibody surrogate (cTN3 PF) has been developed and evaluated for reproductive toxicity. Conventional rat fertility and early embryonic development, embryo-fetal toxicity and pre- and postnatal development studies have been shown to be free of maternal, reproductive, or development toxicity effects, following sustained TNFα inhibition with cTN3 PF. Importantly, these studies have also shown that in marked contrast to a whole IgG anti-TNFα antibody, the PEGylated Fab' antibody cTN3 PF homologous to certolizumab pegol demonstrated negligible fetal exposure following maternal administration during the period of organogenesis. In addition to minimal placental transmission, transfer to milk was lower and fetal absorption negligible compared with the whole IgG antibody cTN3 γ1, resulting in little or no detectable antibody in the plasma of lactating pups.