A tumor-restricted glycoform of podocalyxin is a highly selective marker of immunologically cold high-grade serous ovarian carcinoma

Introduction

Targeted-immunotherapies such as antibody-drug conjugates (ADC), chimeric antigen receptor (CAR) T cells or bispecific T-cell engagers (eg, BiTE®) all aim to improve cancer treatment by directly targeting cancer cells while sparing healthy tissues. Success of these therapies requires tumor antigens that are abundantly expressed and, ideally, tumor specific. The CD34-related stem cell sialomucin, podocalyxin (PODXL), is a promising target as it is overexpressed on a variety of tumor types and its expression is consistently linked to poor prognosis. However, PODXL is also expressed in healthy tissues including kidney podocytes and endothelia. To circumvent this potential pitfall, we developed an antibody, named PODO447, that selectively targets a tumor-associated glycoform of PODXL. This tumor glycoepitope is expressed by 65% of high-grade serous ovarian carcinoma (HGSOC) tumors.

Methods

In this study we characterize these PODO447-expressing tumors as a distinct subset of HGSOC using four different patient cohorts that include pre-chemotherapy, post-neoadjuvant chemotherapy (NACT) and relapsing tumors as well as tumors from various peritoneal locations.

Results

We find that the PODO447 epitope expression is similar across tumor locations and negligibly impacted by chemotherapy. Invariably, tumors with high levels of the PODO447 epitope lack infiltrating CD8+ T cells and CD20+ B cells/plasma cells, an immune phenotype consistently associated with poor outcome.

Discussion

We conclude that the PODO447 glycoepitope is an excellent biomarker of immune "cold" tumors and a candidate for the development of targeted-therapies for these hard-to-treat cancers.

Immunometabolism: A 'Hot' Switch for 'Cold' Pediatric Solid Tumors

Despite the success of immunotherapies in adult solid cancers and pediatric hematological malignancies, limited progress has been made towards implementing these strategies in pediatric solid tumors. These tumors exhibit a high potential to escape antitumor immunity, making them difficult to target by current immunotherapies. This review highlights the altered metabolic pathways in pediatric solid tumors that promote immune escape, and discusses current novel strategies targeting these pathways. We further explore how these strategies could be applied to potentiate immunotherapies for pediatric solid cancers and pose key questions yet to be addressed. Translational challenges to facilitate clinical application of antimetabolic strategies through personalized medicine are identified. We propose preclinical testing of antimetabolic approaches in combination with immunotherapies for pediatric solid cancers.