BackgroundSusceptibility to pepsin digestion of candidate transgene products is regarded an important parameter in the weight-of-evidence approach for allergenicity risk assessment of genetically modified crops. It has been argued that protocols used for this assessment should better reflect physiological conditions encountered in representative food consumption scenarios.AimTo evaluate whether inclusion of more physiological conditions, such as sub-optimal and lower pepsin concentrations, in combination with pancreatin digestion, improved the performance of digestibility protocols used in characterization of protein stability.MethodsFour pairs of established allergens and their related non/weakly-allergenic counterparts (seed albumins, muscle tropomyosins, plant lipid transfer proteins [LTP] and collagens) plus fish parvalbumin, were subjected to nine combinations of pH (1.2–2.5–4.0) and pepsin-to-protein ratio (PPR: 10–1–0.1 U/µg) for pepsin digestion, followed by pancreatin digestion in the presence of bile salts. Digestion was monitored by SDS-PAGE in conjunction with Coomassie staining and immunoblotting using rabbit antisera and human IgE.ResultsAt pH 4.0 and at PPR 0.1 most proteins, both allergen and non-allergen, were highly resistant to pepsin. Under conditions known to favor pepsin proteolysis, the established major allergens Ara h 2, Pru p 3 and Pen a 1 were highly resistant to proteolysis, while the allergen Cyp c 1 was not. However, this resistance to pepsin digestion only made Ara h 2 and to a lesser extent Pen a 1 and Pru p 3 stand out compared to their non-allergenic counterparts. Largely irrespective of preceding pepsin digestion conditions, pancreatin digestion was very effective for all tested proteins, allergens and non-allergens, except for Cyp c 1 and bovine collagen.ConclusionsSub-optimal pH, low pepsin-to protein ratio, and sequential pepsin and pancreatin digestion protocols do not improve the predictive value in distinguish allergens from non-allergens. Digestion conditions facilitating such distinction differ per protein pair.Electronic supplementary materialThe online version of this article (10.1186/s13601-018-0216-9) contains supplementary material, which is available to authorized users.

In these studies we have evaluated the effects of age, genetic background, and housing conditions on the NK-cell activity of nude mice measured in vitro and resistance to tumor metastasis in vivo. BALB/cAnN nude mice exhibited lower levels of NK-cell-mediated cytotoxicity than age-matched N:NIH(S) nude mice maintained under similar housing conditions. The stronger response of N:NIH(S) nude mice was observed also after experimental activation of NK cells by Corynebacterium parvum. Nude mice maintained under barrier conditions have weaker NK-cell activity than mice maintained under conventional conditions. The incidence of experimental pulmonary metastases of allogeneic tumors injected into nude mice was inversely correlated with the levels of NK-cell-mediated cytotoxicity. Thus, 3-week-old BALB/cAnN nude mice raised under barrier conditions were more sensitive to development of experimental metastasis than age-matched N:NIH(S) nude mice maintained under barrier conditions or nude mice of either strain maintained under conventional conditions. In both strains, however, the relative differences in metastatic potential among the tumor cell lines observed in syngeneic recipients were maintained. We conclude that young BALB/cAnN nude mice raised under barrier conditions may provide a valuable in vivo model for studying metastasis of neoplasms.

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Meningiomas are the most common intracranial tumors in dogs. A variety of inflammatory cells have been shown to invade these tumors in people, but little is known about interactions between the immune system and naturally occurring brain tumors in dogs. The purpose of this study was to investigate the presence of a variety of immune cell subsets within canine intracranial meningiomas. Twenty-three formalin-fixed, paraffin-embedded tumor samples were evaluated using immunohistochemistry with antibodies specific for CD3, CD79a, CD18, CD11d (aD), CD45RA, forkhead box P3, and Toll-like receptors 4 and 9. Immune cell infiltration was evident in all samples, with a predominance of CD3 þ T cells. Large numbers of CD18 þ microglia and macrophages were noted surrounding and infiltrating the tumors, and a subset of these cells within the tumor appeared to be CD11d

3007 Background: A phase 1 trial to assess the safety and immunological activity of the combination of varlilumab (V) and nivolumab (N), and recommend a dose of V for the phase 2 study was conducted. Methods: The study was performed using the approved dose of N (3 mg/kg Q2W) and escalating doses of V (0.1, 1, or 10 mg/kg Q2W) in anti-PD-(L)1 naïve patients with advanced cancer. Results: A total of 36 patients (21 CRC, 8 ovarian [OVA], 4 melanoma and 3 SCCHN) were enrolled. Toxicity was consistent with the safety profile of each agent individually; no unexpected toxicities were seen with the combination. No MTD was identified. An OVA cancer patient in the 10 mg/kg cohort had a DLT: hepatitis (G4) and acute kidney injury (G3). A CRC patient in the 10 mg/kg cohort had a drug-related SAE of mixed motor sensory neuropathy (G2) and a CRC patient in the 1 mg/kg cohort had rash (G3). No additional drug related SAEs or DLTs were reported. The majority of tumors were PD-L1 negative (24/27) by IHC at baseline. For patients with post treatment biopsies, PD-L1 expression was observed in 43.5% (10/23) and correlated with increases in CD8 T cell infiltration, consistent with the generation of anti-tumor immunity. Other treatment related biomarker changes included transient increases in serum chemokine levels, and a prominent decrease in circulating Tregs. Biomarker analysis did not clearly differentiate between dose levels, or delineate an optimal V dose. Three patients had objective PR by RECIST [CRC MSI-low (1 mg/kg V), SCCHN (10 mg/kg V) and OVA (10 mg/kg V, uPR)]. The response in the CRC patient is ongoing with a 94% decrease in target lesion diameter and a PFS of 19+ months. There were also 11 patients with SD. Phase 2 cohorts are ongoing in RCC, SCCHN, OVA, CRC and GBM. The Phase 2 portion includes exploration of different dose/regimens of V, including high and low exposure, to better characterize the optimal dosing strategy for V, in combination with a fixed dose of N (240 mg Q2W). Conclusions: The combination of V and N was well tolerated, associated with strong biological signals, and has evidence of clinical activity in subsets of patients with tumor types that are typically resistant to PD-1 inhibitor monotherapy. Clinical trial information: NCT02335918.