A multicenter phase 1 study of solitomab (MT110, AMG 110), a bispecific EpCAM/CD3 T-cell engager (BiTE®) antibody construct, in patients with refractory solid tumors.

We assessed the tolerability and antitumor activity of solitomab, a bispecific T-cell engager (BiTE®) antibody construct targeting epithelial cell adhesion molecule (EpCAM). Patients with relapsed/refractory solid tumors not amenable to standard therapy received solitomab as continuous IV infusion in a phase 1 dose-escalation study with six different dosing schedules. The primary endpoint was frequency and severity of adverse events (AEs). Secondary endpoints included pharmacokinetics, pharmacodynamics, immunogenicity, and antitumor activity. Sixty-five patients received solitomab at doses between 1 and 96 µg/day for ≥28 days. Fifteen patients had dose-limiting toxicities (DLTs): eight had transient abnormal liver parameters shortly after infusion start or dose escalation (grade 3, n = 4; grade 4, n = 4), and one had supraventricular tachycardia (grade 3); all events resolved with solitomab discontinuation. Six patients had a DLT of diarrhea: four events resolved (grade 3, n = 3; grade 4, n = 1), one (grade 3) was ongoing at the time of treatment-unrelated death, and one (grade 3) progressed to grade 5 after solitomab discontinuation. The maximum tolerated dose was 24 µg/day. Overall, 95% of patients had grade ≥3 treatment-related AEs, primarily diarrhea, elevated liver parameters, and elevated lipase. Solitomab half-life was 4.5 hours; serum levels plateaued within 24 hours. One unconfirmed partial response was observed. In this study of a BiTE® antibody construct targeting solid tumors, treatment of relapsed/refractory EpCAM-positive solid tumors with solitomab was associated with DLTs, including severe diarrhea and increased liver enzymes, which precluded dose escalation to potentially therapeutic levels.

How the bioanalytical scientist plays a key role in interdisciplinary project teams in the development of biotherapeutics - a reflection of the European Bioanalysis Forum.

The bioanalytical scientist plays a key role in the project team for the drug development of biotherapeutics from the discovery to the marketing phase. Information from the project team members is required for assay development and sample analysis during the discovery, preclinical and clinical phases of the project and input is needed from the bioanalytical scientist to help data interpretation. The European Bioanalysis Forum target team 20 discussed many of the gaps in information and communication between the bioanalytical scientist and project team members as a base for providing a perspective on the bioanalytical scientist's role and interactions within the project team.

'Less is More': defining modern bioanalysis.

The 4th Open Symposium of the European Bioanalytical Forum entitled 'Less is More' was held on 16-18 November 2011 at the Hesperia Tower Hotel, Barcelona, Spain. More than 50 interesting presentations were delivered covering areas with interest for the small- and large-molecule community - biomarker validation; regulations, including an update on new and emerging guidelines and on Global harmonization; technology updates; incurred sample stability; microdosing; dried blood spots and microsampling; challenges of 'free' and 'total' macromolecule quantification; stability issues in ligand binding assays or anomalous results. In excess of 450 delegates from more than 170 institutes and companies (industry, regulators and academia) from all global regions participated in the open and stimulating discussions. This manuscript provides an overview of the highlights discussed at the meeting.

The interleukin-2 antagonizing antibody MT204 delays allogeneic skin graft rejection in non-human primates and is well tolerated.

MT204 is a humanized IgG1 antibody specific for interleukin-2 (IL-2) of human and rhesus monkey origin. It potently antagonizes IL-2 signaling in both CD25(+) and CD25(-) cells by a unique mode of action. MT204 can not only prevent soluble IL-2 from binding to the intermediate affinity IL-2 receptors but can also antagonize IL-2 that is already bound to the CD25 subunit of high affinity IL-2 receptors on the cell surface. As initial steps toward development of a therapeutic antibody, pharmacokinetics (PK) and tolerability of MT204, as well as efficacy were investigated in rhesus monkeys. MT204 was infused by single escalating (2, 10 and 50mg/kg) or repeat dose administrations (50mg/kg, 1 ×/week for 3 weeks). Over the course of the experiment, the animals were regularly observed for clinical adverse reaction and bled for laboratory investigations (PK, hematology, chemical chemistry and leukocyte subset analysis). For the efficacy study, six rhesus monkeys were grafted with MHC-mismatched rhesus skin and infused with MT204 (50mg/kg), on the day of transplantation and again on days 5 and 12 post grafting. Efficacy was determined by assessment of graft necrosis at different time-points. No obvious adverse effects were observed clinically after single infusion, or after three repeated infusions of 50mg/kg and no MT204-related toxic effects were revealed by hematology or clinical chemistry. In the efficacy study, MT204-treated animals showed a significant delay in graft rejection versus control animals (p=0.025 by Log-rank test). The characteristics of MT204, displaying linear pharmacokinetics, half-life in the range expected for a human IgG, benign safety profile and signs of efficacy, warrant further development of this antibody for therapy.

From challenges to solutions. European Bioanalysis Forum 3rd Annual Open Symposium, Hesperia Towers, Barcelona, Spain, 1-3 December 2010.

The European Bioanalysis Forum is a bioanalytical nonprofit organization comprised of European pharmaceutical companies (27 members to date) and currently expanding to include CROs as well. The European Bioanalysis Forum provides a broad European bioanalytical network for the discussion of scientific, technological and regulatory topics of bioanalytical interest. The 3rd Annual Open Symposium was again much anticipated after the two previous successful meetings. The symposium included sessions on thinking outside the 'commodity' box, bioanalytical challenges with blood, global harmonization, assay platforms, dried blood spots, immunogenicity, matrix effects, anomalous results, biomarkers and two plenary technology sessions hosted by the Platinum sponsors. Experts and key opinion leaders were invited as guest speakers. A total of 424 delegates registered from 113 companies representing a large percentage of the European bioanalytical community. In addition to 48 oral presentations, 88 posters were presented and there was a vendor exposition of 40 companies.

Therapeutic window of an EpCAM/CD3-specific BiTE antibody in mice is determined by a subpopulation of EpCAM-expressing lymphocytes that is absent in humans.

MuS110 is a BiTE antibody bispecific for murine EpCAM (CD326) and murine CD3. A recent study has shown that microS110 has significant anti tumor activity at well-tolerated doses as low as 5 microg/kg in orthotopic breast and lung cancer models (Amann et al. in Cancer Res 68:143-151, 2008). Here, we have explored the safety profile of microS110 at higher doses. Escalation to 50 microg/kg microS110 caused in mice transient loss of body weight, and transient piloerection, hypomotility, hypothermia and diarrhoea. These clinical signs coincided with serum peaks of TNF-alpha, IL-6, IL-2, IFN-gamma and IL-4, and an increase of surface markers for T cell activation. Because activation of T cells in response to BiTE antibodies is typically dependent on target cells, we analyzed mouse blood for the presence of EpCAM(+) cells. Various mouse strains presented with a subpopulation of 2-3% EpCAM(+) blood cells, mostly B and T lymphocytes, which was not detected in human blood samples. In vitro experiments in which the number of EpCAM(+) cells in blood samples was either reduced or increased suggested that both T cell activation and cytokine release in response to microS110 was dependent on the number of target-expressing cells. In support for a role of EpCAM(+) lymphocytes in the observed side effects, reduction of EpCAM(+) blood cells in mice via a low-dose pre treatment with microS110 dramatically increased the tolerability of animals up to at least 500 microg/kg of the BiTE antibody. This high tolerability to microS110 occurred in the presence of non-compromised T cells. No damage to EpCAM(+) epithelial tissues was evident from histopathological examination of animals daily injected with 100 microg/kg microS110 for 28 days. In summary, these observations suggest that side effects of microS110 in mice were largely caused by an acute T cell activation that was triggered by a subpopulation of EpCAM(+) lymphocytes. Because humans have extremely low numbers of EpCAM(+) cells in blood, this toxicity of an EpCAM-specific BiTE may be specific for mice.