Details

Autor(en) / Beteiligte

• Drapkin, Ronny
• Jung, Euihye
• Bradshaw, Chelsea
• Demars, Leslie
• Mosher, Rebecca

Titel

EP014/#408 Evaluation of NAPI2B expression in a well annotated longitudinal tissue series of ovarian serous carcinomas

Ist Teil von

• International journal of gynecological cancer, 2022-12, Vol.32 (Suppl 3), p.A54-A54

Ort / Verlag

Oxford: BMJ Publishing Group Ltd

Erscheinungsjahr

2022

Beschreibungen/Notizen

• ObjectivesUpifitimab rilsodotin (UpRi) is a first-in-class NaPi2b-targeting ADC with a novel scaffold-linker-payload that enables high drug-to-antibody ratio and controlled bystander effect. NaPi2b is , a sodium-dependent phosphate transporter broadly expressed in high-grade serous epithelial ovarian, fallopian tube and primary peritoneal cancers. Emerging UpRi data suggests a relationship between patients with higher expression of NaPi2b, the SLC34a2 gene product, and clinical activity, with a generally well tolerated safety profile (Richardson et al., SGO 2022). However, change in NaPi2b expression in ovarian cancer over the course of disease has not been well defined.Methods11 individuals diagnosed with high grade serous ovarian cancer had tumor biopsies evaluated for NaPi2b expression at more than one time point. These included matched samples taken from debulking procedures/post-chemotherapy (n=5); pretreatment biopsy/post neoadjuvant (n=4); pretreatment/post neoadjuvant/at progression (n=2). Tumor samples were evaluated by immunohistochemistry (IHC) using a rabbit antibody to detect NaPi2b expression, and a tumor proportion score (TPS) was calculated. High NaPi2b expression was defined as TPS ≥75%.Results7/11 (64%) individuals had an initial sample with high NaPi2b expression. 6 of these 7 subjects (86%) remained NaPi2b high through their matched samples; 8/11 (73%) of individuals maintained their NaPi2b status through matched samples. Of the three individuals who had a change in expression status, two showed increased NaPi2b expression above TPS ≥ 75% following treatment; one showed decreased expression.ConclusionsIn this cohort , NaPi2b expression status was maintained over the treatment course in the majority of evaluated individuals reinforcing that this marker remains consistent throughout the disease course.