Structural Decoding of the Netrin-1/UNC5 Interaction and its Therapeutical Implications in Cancers

Netrin-1 has been shown to be up-regulated in a fraction of human cancers as a mechanism to allow these tumors to escape the pro-apoptotic activity of some of its main dependence receptors, the UNC5 homologs (UNC5H). Here we identify the V-2 domain of netrin-1 to be important for its interaction with the Ig1/Ig2 domains of UNC5H2. We generate a humanized anti-netrin-1 antibody that disrupts the interaction between netrin-1 and UNC5H2 and triggers death of netrin-1-expressing tumor cells in vitro. We also present evidence that combining the anti-netrin-1 antibody with epidrugs such as decitabine could be effective in treating tumors showing no or modest netrin-1 expression. These results support that this antibody is a promising drug candidate.

Characterization of a surrogate murine antibody to model anti-human CD3 therapies

Fc-modified anti-human CD3ε monoclonal antibodies (mAbs) are in clinical development for the treatment of autoimmune diseases. These next generation mAbs have completed clinical trials in patients with type-1 diabetes and inflammatory bowel disease demonstrating a narrow therapeutic window. Lowered doses are ineffective, yet higher pharmacologically-active doses cause an undesirable level of adverse events. Thus, there is a critical need for a return to bench research to explore ways of improving clinical outcomes. Indeed, we recently reported that a short course of treatment affords synergy, providing long-term disease amelioration when combining anti-mouse CD3 and anti-mouse tumor necrosis factor mAbs in experimental arthritis. Such strategies may widen the window between risk and benefit; however, to more accurately assess experimentally the biology and pharmacology, reagents that mimic the current development candidates were required. Consequently, we engineered an Fc-modified anti-mouse CD3ε mAb, 2C11-Novi. Here, we report the functional characterization of 2C11-Novi demonstrating that it does not bind FcγR in vitro and elicits little cytokine release in vivo, while maintaining classical pharmacodynamic effects (CD3-TCR downregulation and T cell killing). Furthermore, we observed that oral administration of 2C11-Novi ameliorated progression of remitting-relapsing experimental autoimmune encephalitis in mice, significantly reducing the primary acute and subsequent relapse phase of the disease. With innovative approaches validated in two experimental models of human disease, 2C11-Novi represents a meaningful tool to conduct further mechanistic studies aiming at exploiting the immunoregulatory properties of Fc-modified anti-CD3 therapies via combination therapy using parenteral or oral routes of administration.

Combination therapies in the context of anti-CD3 antibodies for the treatment of autoimmune diseases

Non-Fc receptor binding anti-CD3 antibodies are in clinical development for the treatment of autoimmune diseases. Results from phase 1/2 clinical trials suggest that teplizumab and otelixizumab preserve residual beta-cell function in patients with recent onset type 1 diabetes. Similarly, encouraging results from phase 1/2 clinical trials have been reported for visilizumab and foralumab in patients with inflammatory bowel disease. However, these CD3-directed therapies have recently suffered setbacks due to the reported inefficacy results observed during phase 2/3 clinical trials due to low dosages or inappropriate clinical endpoints. Due to adverse events observed in the phase 1/2 pilot trials, the dose of anti-CD3 antibodies was reduced in the phase 2/3 confirmatory trials. Thus, these studies reveal a narrow therapeutic window of anti-CD3-based therapies in which low doses are ineffective and higher pharmacologically active doses cause intolerable levels of adverse effects. Combining anti-CD3 antibodies with other drugs may be the most effective way to reduce toxicity while allowing significant therapeutic benefit. Indeed, monotherapy also has its limits from the perspective of targeting only a single arm of the immune process. Notably, several recent experimental studies show potent synergy between anti-CD3 antibodies and various therapeutic modalities for the treatment of autoimmune diseases. In this review we present a review of preclinical studies evaluating combination therapies using anti-CD3 antibodies for the treatment of autoimmune diseases.

Phase I, double-blind, randomized, placebo-controlled, dose-escalation study of NI-0401 (a fully human anti-CD3 monoclonal antibody) in patients with moderate to severe active Crohn's disease

BACKGROUND

NI-0401 is a fully human monoclonal antibody, which binds to the CD3 subunit of the T-cell receptor, causing modulation of T-cell activity. We investigated the safety and the ability to modulate the TCR-CD3 complex of NI-0401 in patients with active Crohn's disease (CD).

METHODS

A double-blind, placebo-controlled, randomized, multicenter, dose-escalating trial was conducted in CD patients age 18-70 years, a Crohn's Disease Activity Index (CDAI) of 220-450, and detectable levels of C-reactive protein. The primary outcome was safety and the ability of NI-0401 to modulate the TCR-CD3 complex on T cells. Efficacy parameters included the proportion of patients achieving remission (CDAI <150), clinical response (CDAI fall ≥100), and change from baseline in the CD Endoscopy Index of Severity (CDEIS).

RESULTS

Forty patients received placebo (n = 7) or NI-0401 (n = 33) 0.05-10 mg daily for 5 days. NI-0401 doses ≤1 mg were well tolerated. Infusion reactions occurred at doses ≥2 mg. The extent and duration of TCR-CD3 modulation increased with dose. No differences between groups were observed in the proportions of patients achieving clinical remission or response. The mean CDEIS at week 6 differed significantly between the 1-mg and placebo group.

CONCLUSIONS

NI-0401 was tolerated at doses ≤1 mg with manageable side effects. NI-0401 induced a dose-dependent modulation of the TCR-CD3 complex. No significant improvement of CDAI was observed but 1 mg NI-0401 demonstrated an improvement in CDEIS.

Pivotal involvement of Fcgamma receptor IIA in the neutralization of lipopolysaccharide signaling via a potent novel anti-TLR4 monoclonal antibody 15C1

The mammalian Toll-like receptor (TLR) family has evolved to sense pathogens in the environment and protect the host against infection. TLR4 recognizes lipopolysaccharide (LPS) from Gram-negative bacteria and induces a signaling cascade that, when exaggerated, has been associated with severe sepsis. We have generated a TLR4-specific monoclonal antibody, 15C1, which neutralizes LPS-induced TLR4 activation in a dose-dependent manner. 15C1 potently blocks the effects of LPS on a panel of primary cells and cell lines in vitro. The binding of 15C1 was mapped to an epitope in the second portion of the extracellular region of TLR4, which has been shown previously to be functionally important in the recognition of LPS. Furthermore, we demonstrate a novel mechanism of inhibition, as the effects of 15C1 are partially Fc-dependent, involving the regulatory Fcgamma receptor IIA (CD32A). In addition to introducing 15C1 as a potent clinical candidate for use in the treatment of LPS-mediated indications, our work demonstrates a newly discovered pathway whose manipulation is pivotal in achieving optimal neutralizing benefit.

Short-Term Treatment With Anti-CD3 Antibody Reduces the Development and Progression of Atherosclerosis in Mice

Background— Atherosclerosis is a chronic inflammatory disease of the large arteries that is the primary cause of heart disease and stroke. Anti-CD3–specific antibodies suppress immune responses by antigenic modulation of the CD3 antibody/T-cell receptor complex. Their unique capacity to restore self-tolerance in a mouse model of diabetes and, importantly, in patients with recent-onset type 1 diabetes involves transforming growth factor-β–dependent mechanisms via expansion and/or activation of regulatory T cells. We hypothesized that treatment with anti-CD3–specific antibodies might inhibit atherosclerosis development and progression in mice.

Methods and Results— Low-density lipoprotein receptor–deficient mice were fed a high-cholesterol diet for 13 or 24 weeks. Anti-CD3 antibody was administered on 5 consecutive days beginning 1 week before or 13 weeks after the high-cholesterol diet was initiated, respectively. Control mice were injected in parallel with phosphate-buffered saline. Anti-CD3 antibody therapy reduced plaque development when administered before a high-cholesterol diet and markedly decreased lesion progression in mice with already established atherosclerosis. We found increased production of the antiinflammatory cytokine transforming growth factor-β in concanavalin A–stimulated lymph node cells and enhanced expression of the regulatory T-cell marker Foxp3 in spleens of anti-CD3 antibody–treated mice. A higher percentage of apoptotic cells within the plaques of anti-CD3 antibody–treated mice was also observed.

Conclusions— Altered disease progression, combined with the emergence of this particular cytokine pattern, indicates that short-term treatment with an anti-CD3 antibody induces a regulatory T-cell phenotype that restores self-tolerance in a mouse model of atherosclerosis.

An evaluation of gastric emptying times in pregnancy and the puerperium

In a controlled study, gastric emptying was measured during the three trimesters of pregnancy and after delivery, using an indirect paracetamol absorption technique. The peak plasma paracetamol concentration, time to reach the peak, and the area under the plasma paracetamol concentration-time curve, were determined. As compared to nonpregnant controls, there were no significant differences in the gastric emptying times of women in the three trimesters of pregnancy and of mothers from 18 h after delivery onwards. Gastric emptying was significantly delayed in mothers within 2 h after delivery (p < 0.01); median (range) values of peak paracetamol concentration, time to reach the peak and the area under the paracetamol concentration-time curve for this group were 12.5 (0.2-30.5) mg.l-1, 120 (30-120) min and 3.8 (0.1-16.6) mg.l-1 x h respectively, and 20.8 (8.6-64.5) mg.l-1, 40 (10-120) min and 13.5 (5.5-28.8) mg.l-1 x h respectively, for the nonpregnant control group (p < 0.01). Repeated measurements of gastric emptying in these women on the second postpartum day showed no significant delay.

The effect of a priming epidural injection of adrenaline on epidural blockade with bupivacaine

Twenty-four patients receiving epidural anaesthesia were studied to test the hypothesis that 1:200,000 adrenaline administered into the epidural space 5 minutes before 20 ml bupivacaine 0.5% would improve nerve block and delay systemic absorption of the local anaesthetic. Group A/B received 20 ml adrenaline 1:200,000 5 minutes before 20 ml bupivacaine 0.5%, group S/BA 20 ml saline followed by 20 ml bupivacaine 0.5% with 100 micrograms adrenaline, and group S/B saline 20 ml followed by 20 ml plain bupivacaine 0.5%. Mean maximum plasma concentrations of bupivacaine tended to be lower in the adrenaline groups. A delay in the time to peak plasma concentration of bupivacaine was noted in the A/B group; this indicated that priming with adrenaline may be effective at delaying early systemic uptake of the local anaesthetic. In both adrenaline groups a more prolonged epidural block and increased efficacy were noted, although this was only significant for the duration of block at T6 (p = 0.023) and duration of motor block at Bromage level 1 (p = 0.016) in group A/B. There seems little clinical advantage in administering adrenaline 5 minutes before bupivacaine.