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Background RO7122290 (RO) is a bispecific antibody-like fusion protein that simultaneously targets FAP, abundantly expressed by cancer-associated fibroblasts in most solid tumors, and 4-1BB, transiently expressed on activated T cells. Pre-clinical experiments revealed strong intra-tumoral CD8+ T cells infiltration in FAP-positive tumors, cytokines induction and significant anti-tumor activity mediated by RO (signal 2 of T cell activation), upon TCR/CD3 engagement (signal 1) or in combination with atezolizumab (ATZ). In this first-in-human study, the pharmacodynamic (PD) effects of RO were assessed, both as single agent (SA) (Part A) and in combination with ATZ (Part B). Methods Pts with advanced and/or metastatic solid tumors were eligible for this ongoing Phase 1/1b trial (EUDRACT 2017-003961-83). RO was administered intravenously, weekly (QW) at escalating dose levels (DLs). In Part A, 62 pts were treated at 13 DLs of RO, dose range 5–2000 mg. In Part B, 39 pts were treated at 8 DLs of RO, dose range 45–2000 mg, with ATZ 1200 mg Q3W. Secondary biomarker objective was characterization of PD effects in tumor tissue and blood. The endpoints were change from baseline in intra-tumoral density (cell/mm2) and proliferation (Ki67) of CD8+ T cells measured by immunohistochemistry (IHC), and change in activation (4-1BB) and proliferation (Ki67) of peripheral CD8+ T cells measured by flow cytometry. Exploratory objectives were characterization of PD effects in plasma/serum and measurement of intra-tumoral immune activation. The endpoints were change in peripheral cytokines (TNF-alfa, IFN-gamma, IL-6) and soluble(s) factors (sCD25, s4-1BB) concentration measured by ELISA, and intra-tumoral changes in gene expression measured by RNAseq. Results In the periphery, we observed transient expression of 4-1BB on CD4+ and CD8+ T cells, along with secretion of s4-1BB and inflammatory cytokines, suggesting 4-1BB targeting and potent T cell activation. The concomitant induction of proliferating T cells indicated the potential association to priming and formation of tumor-reactive T cells. In the tumor, we detected increased CD8+ T cells infiltration and proliferation, in both Parts. Proliferating CD8+ T cells increased in both tumor nests and surrounding stroma, with a preferential accumulation in the latter. RNAseq analysis revealed induction of 4-1BB, PD-1 and IFN-gamma, indicating intra-tumoral T cells activation in Part B. Conclusions PD activity was consistent with the postulated MoA, confirming RO to be a potent tumor-targeted 4-1BB agonist in the clinical setting. Our observations suggest that RO can synergize with endogenous T cell receptor stimulation, both as SA and in combination with ATZ.

Background Ideally, monoclonal antibodies provide selective treatment by targeting the tumour, without affecting normal tissues. Therefore, antibody imaging is of interest, preferably in early stages of drug development. However, the imaging signal consists of specific, as well as non-specific, uptake. The aim of this study was to assess specific, target-mediated uptake in normal tissues, with immuno-PET in a phase I dose escalation study, using the anti-CD44 antibody RG7356 as example. Results Data from thirteen patients with CD44-expressing solid tumours included in an imaging sub-study of a phase I dose escalation clinical trial using the anti-CD44 antibody RG7356 was analysed. 89Zirconium-labelled RG7356 (1 mg; 37 MBq) was administered after a variable dose of unlabelled RG7356 (0 to 675 mg). Tracer uptake in normal tissues (liver, spleen, kidney, lung, bone marrow, brain and blood pool) was used to calculate the area under the time antibody concentration curve (AUC) and expressed as tissue-to-blood AUC ratios. Within the dose range of 1 to 450 mg, tissue-to-blood AUC ratios decreased from 10.6 to 0.75 ± 0.16 for the spleen, 7.5 to 0.86 ± 0.18 for the liver, 3.6 to 0.48 ± 0.13 for the bone marrow, 0.69 to 0.26 ± 0.1 for the lung and 1.29 to 0.56 ± 0.14 for the kidney, indicating dose-dependent uptake. In all patients receiving ≥ 450 mg (n = 7), tumour uptake of the antibody was observed. Conclusions This study demonstrates how immuno-PET in a dose escalation study provides a non-invasive technique to quantify dose-dependent uptake in normal tissues, indicating specific, target-mediated uptake. Electronic supplementary material The online version of this article (10.1186/s13550-018-0358-8) contains supplementary material, which is available to authorized users.

Purpose: CD44, a cell surface glycoprotein, plays important roles in the development, progression, and metastasis of various tumor types. The aim of this study was to investigate how the expression of CD44 isoforms influences the interaction with hyaluronic acid (HA) and how differential isoform expression impacts antitumoral responses in vivo to treatment with RG7356, a humanized anti-CD44 antibody inhibiting CD44–HA interaction. Experimental Design: CD44 isoform expression on various tumor cell lines was analyzed by RNASeq while data on patients with different tumor types were obtained from the publicly available TCGA RNASeq dataset as well as a phase I clinical study (NCT01358903). We analyzed the link between HA production and CD44 isoform expression as well as the consequences of blocking the CD44-mediated cell adhesion to HA using RG7356. The correlation between CD44 isoform expression and antitumor response to RG7356 treatment was investigated in the corresponding murine xenograft in vivo models as well as in a subset of patients treated with RG7356 from a recently completed phase I clinical trial. Results: CD44 isoform expression, in particular expression of CD44s, is associated with HA production and predicts response to treatment with RG7356 in tumor xenograft models. Furthermore, patient data suggest that CD44 isoform status is a potential predictive biomarker for clinical response to treatment with RG7356. Conclusions: We provide new insights into the close interplay between CD44 and HA and a potential biomarker to enrich patient responses to RG7356 in the clinic. Clin Cancer Res; 21(12); 2753–62. ©2015 AACR.

Double-stranded ribonucleic acid (dsRNA) serves as a danger signal associated with viral infection and leads to stimulation of innate immune cells. In contrast, the immunostimulatory potential of single-stranded RNA (ssRNA) is poorly understood and innate immune receptors for ssRNA are unknown. We report that guanosine (G)- and uridine (U)-rich ssRNA oligonucleotides derived from human immunodeficiency virus–1 (HIV-1) stimulate dendritic cells (DC) and macrophages to secrete interferon-α and proinflammatory, as well as regulatory, cytokines. By using Toll-like receptor (TLR)–deficient mice and genetic complementation, we show that murine TLR7 and human TLR8 mediate species-specific recognition of GU-rich ssRNA. These data suggest that ssRNA represents a physiological ligand for TLR7 and TLR8.

Loxoribine (7-allyl-7,8-dihydro-8-oxo-guanosine) acts as synthetic adjuvant in anti-tumor responses. Here we first demonstrate that loxoribine activates cells of the innate immune system selectively via the Toll-like receptor (TLR) 7/MyD88-dependent signaling pathway. TLR7- and MyD88-deficient immune cells fail to proliferate or produce cytokines in response to loxoribine, and genetic complementation of TLR7-deficient cells with murine or human TLR7 confers responsiveness. Subsequently we show that cellular activation by loxoribine and resiquimod (R-848), a stimulus for TLR7 and TLR8, depends on acidification and maturation of endosomes and targets MyD88 to vesicular structures with lysosomal characteristics. This mode of TLR7 and TLR8 action resembles CpG-DNA-driven TLR9 activation. We thus conclude that TLR7, 8 and 9 form a functional subgroup within the TLR family that recognizes pathogen-associated molecular patterns in endosomal/lysosomal compartments.

10007b Background: WD/DD LPS are a prominent subset (15%) of sarcomas, where cytotoxic treatments have limited activity. MDM2 gene amplifications (and MDM2 overexpression) are potential molecular drivers. We report a neoadjuvant study of RG7112, a small molecule MDM2 antagonist, in chemotherapy-naive primary or relapsed LPS patients (pts) eligible for tumor resection. Methods: Pts with WD/DD LPS were treated orally at 1440 mg/m2 (Ph 1 MTD) QD for 10 days on a 28 day cycle. 3 cycles were planned, followed by complete resection. PK was collected d1 and d8 in cycle 1 (C1), with tumor biopsies collected at baseline and d8. Tumor p53 mutation (AmpliChip), MDM2 amplification (SISH) and expression (PCR), apoptosis (TUNEL) and proliferation (Ki67) were compared pre-treatment and at d8, along with serum MIC-1 (macrophage inhibitory cytokine-1), a p53 transcriptional target. Results: Between June-Dec 2010, 20 pts (12 M/8 F, med. 62y) completed pre-treatment and d8 biopsy. 12 pts had WD and 8 DD LPS. 9 were untreate...