Emerging antibody therapies for pancreatic adenocarcinoma: a review of recent phase 2 trials

Introduction: Pancreatic adenocarcinoma is now the third-leading cause of cancer-related deaths in the US which can be attributed to rising incidence, diagnosis at advanced stages and early development of metastasis. Systemic therapy remains palliative with early development of resistance possibly related to the constitutive activation of 'undruggable' KRAS, immunosuppressive microenvironment, and intense desmoplasia. The advancements in molecular biology has led to the development and investigation of targeted and immune therapeutics.Areas covered: This study provides a comprehensive review of the literature to further the understanding of molecular targets with their respective antibody-based therapies in clinical development in pancreatic cancer. PubMed was systematically searched for English-language articles discussing antibody-based therapies under phase 2 clinical trial investigation in pancreatic adenocarcinoma.Expert opinion: PDAC remains highly resistant to chemotherapy with no significant improvement in survival for patients with advanced or metastatic cancer. Unfortunately, the majority of the antibody-based targeted and immune therapeutics have failed to meet their primary efficacy endpoints in early phase trials. However, there are a few promising antibody-based drugs with intriguing preliminary data that merit further investigation, while many more continue to be developed and investigated preclinically, and in early phase trials.

Low-Dose Radiation Conditioning Enables CAR T Cells to Mitigate Antigen Escape

CD19 chimeric antigen receptors (CARs) have demonstrated great efficacy against a range of B cell malignancies. However, antigen escape and, more generally, heterogeneous antigen expression pose a challenge to applying CAR therapy to a wide range of cancers. We find that low-dose radiation sensitizes tumor cells to immune rejection by locally activated CAR T cells. In a model of pancreatic adenocarcinoma heterogeneously expressing sialyl Lewis-A (sLeA), we show that not only sLeA⁺ but also sLeA^- tumor cells exposed to low-dose radiation become susceptible to CAR therapy, reducing antigen-negative tumor relapse. RNA sequencing analysis of low-dose radiation-exposed tumors reveals the transcriptional signature of cells highly sensitive to TRAIL-mediated death. We find that sLeA-targeted CAR T cells produce TRAIL upon engaging sLeA⁺ tumor cells, and eliminate sLeA^- tumor cells previously exposed to systemic or local low-dose radiation in a TRAIL-dependent manner. These findings enhance the prospects for successfully applying CAR therapy to heterogeneous solid tumors. Local radiation is integral to many tumors' standard of care and can be easily implemented as a CAR conditioning regimen.