Tumor targeted 4-1BB agonist antibody-albumin fusions with high affinity to FcRn induce anti-tumor immunity without toxicity.

Costimulation of tumor-infiltrating T lymphocytes by anti-4-1BB monoclonal antibodies (mAbs) has shown anti-tumor activity in human trials, but can be associated with significant off-tumor toxicities involving FcγR interactions. Here, we introduce albumin-fused mouse and human bispecific antibodies with clinically favorable pharmacokinetics designed to confine 4-1BB costimulation to the tumor microenvironment. These Fc-free 4-1BB agonists consist of an EGFR-specific VHH antibody, a 4-1BB-specific scFv, and a human albumin sequence engineered for high FcRn binding connected in tandem (LiTCo-Albu). We demonstrate in vitro cognate target engagement, EGFR-specific costimulatory activity, and FcRn-driven cellular recycling similar to non-fused FcRn high-binding albumin. The mouse LiTCo-Albu exhibited a prolonged circulatory half-life and in vivo tumor inhibition, with no indication of 4-1BB mAb-associated toxicity. Furthermore, we show a greater therapeutic effect when used in combination with PD-1-blocking mAbs. These findings demonstrate the feasibility of tumor-specific LiTCo-Albu antibodies for safe and effective costimulatory strategies in cancer immunotherapy.

An Fc-free EGFR-specific 4-1BB-agonistic Trimerbody Displays Broad Antitumor Activity in Humanized Murine Cancer Models without Toxicity.

PURPOSE: The induction of 4-1BB signaling by agonistic antibodies can drive the activation and proliferation of effector T cells and thereby enhance a T-cell-mediated antitumor response. Systemic administration of anti-4-1BB-agonistic IgGs, although effective preclinically, has not advanced in clinical development due to their severe hepatotoxicity. EXPERIMENTAL DESIGN: Here, we generated a humanized EGFR-specific 4-1BB-agonistic trimerbody, which replaces the IgG Fc region with a human collagen homotrimerization domain. It was characterized by structural analysis and in vitro functional studies. We also assessed pharmacokinetics, antitumor efficacy, and toxicity in vivo. RESULTS: In the presence of a T-cell receptor signal, the trimerbody provided potent T-cell costimulation that was strictly dependent on 4-1BB hyperclustering at the point of contact with a tumor antigen-displaying cell surface. It exhibits significant antitumor activity in vivo, without hepatotoxicity, in a wide range of human tumors including colorectal and breast cancer cell-derived xenografts, and non-small cell lung cancer patient-derived xenografts associated with increased tumor-infiltrating CD8+ T cells. The combination of the trimerbody with a PD-L1 blocker led to increased IFNγ secretion in vitro and resulted in tumor regression in humanized mice bearing aggressive triple-negative breast cancer. CONCLUSIONS: These results demonstrate the nontoxic broad antitumor activity of humanized Fc-free tumor-specific 4-1BB-agonistic trimerbodies and their synergy with checkpoint blockers, which may provide a way to elicit responses in most patients with cancer while avoiding Fc-mediated adverse reactions.

Synthetic TILs: Engineered Tumor-Infiltrating Lymphocytes With Improved Therapeutic Potential.

Immunotherapy has emerged as an effective and life-changing approach for several types of cancers, both liquid and solid tumors. In combination with traditional treatments such as radiotherapy and/or chemotherapy, immune checkpoints inhibitors have improved prognosis and overall survival of patients with advanced melanoma and many other cancers. Among adoptive cell therapies (ACT), while chimeric antigen receptor T cell therapies have demonstrated remarkable efficacy in some hematologic malignancies, such as B cell leukemias, their success in solid tumors remains scarce due to the characteristics of the tumor microenvironment. On the other hand, ACT using tumor-infiltrating lymphocytes (TILs) is arguably the most effective treatment for metastatic melanoma patients, but even if their isolation has been achieved in epithelial tumors, their success beyond melanoma remains limited. Here, we review several aspects impacting TIL- and gene-modified "synthetic" TIL-based therapies and discuss future challenges that must be addressed with these approaches.

[Intracranial germ cell tumours: A 21-year review]. / Tumores germinales intracraneales: revisión de 21 años.

INTRODUCTION: Intracranial germ cell tumours are rare in children. They are a heterogeneous group of neoplasms that show different clinical manifestations despite having a common origin. PATIENTS AND METHODS: A retrospective analysis was carried out on the epidemiological and histological characteristics, clinical manifestations, and outcomes of 20 patients diagnosed with intracranial germ cell tumours in the Niño Jesús Children's Hospital of Madrid from 1994-2014. RESULTS: A total of 20 patients were identified: 14 boys and 6 girls. The mean age was 11.1 years (range 2-18 years). Histological confirmation of the diagnosis was obtained in 95% of the patients. Of the 20 patients, 14 were pure germinoma (70%) and 6 non-seminomatous germ cell tumours (30%). The most frequent locations were pineal (45%) and suprasellar (45%). The most frequent clinical symptoms in pineal tumours at diagnosis were headache and vomiting (77.77%), followed by visual disturbances (44.4%). In suprasellar tumours it was polydipsia and polyuria (100%). At diagnosis, 90% of the patients received radiotherapy, and 55% received chemotherapy combined with radiotherapy. There was a relapse in 4 patients (20%), and 3 of them died. Overall survival was 80%; 85.7% for pure germinomas and 60% for non-seminomatous germ cell tumours. CONCLUSIONS: The most common histological subtype was pure germinoma. Germ cell tumours include heterogeneous disease entities that have a variable prognosis. Thus, an accurate diagnosis is vital for patient counselling and treatment planning.