Huntsman, David

Abstract Background Opportunistic bilateral salpingectomy (OBS), the removal of fallopian tubes during hysterectomy or instead of tubal ligation, is recommended to reduce ovarian cancer risk. However, data on the effectiveness of prophylactic OBS is limited. Methods This population-based retrospective cohort included individuals aged 18–80 in Ontario, Canada, who underwent OBS or comparator surgeries (hysterectomy with ovarian and tubal conservation or tubal ligation) from 2011 to 2023. Individuals with gynecologic cancer before or within six months of surgery were excluded. Hazard ratios and 95% confidence intervals were estimated using Cox proportional hazards regression. Sensitivity analyses varied the time between surgery and cancer diagnosis to account for pre-existing serous tubal intraepithelial carcinomas. Results Among 196,839 individuals, 57,941 underwent OBS and 138,898 underwent comparator surgeries. 142 epithelial ovarian cancers were diagnosed (19 in the OBS group and 123 in the comparator surgery group). OBS was associated with reduced risk of any ovarian carcinoma, with an adjusted hazard ratio (aHR) of 0.60 (95% CI, 0.36 to 0.98). For serous ovarian carcinoma (high- and low-grade combined due to missing grade data), the aHR was 0.47 (95% CI, 0.22 to 0.99). Sensitivity analyses with 12- and 18-month intervals showed aHRs of 0.59 (95% CI, 0.35 to 0.99) and 0.60 (95% CI, 0.35 to 1.01) for all ovarian carcinomas, and 0.49 (95% CI, 0.23 to 1.01) and 0.47 (95% CI, 0.22 to 0.99) for serous ovarian carcinoma, respectively. Conclusions OBS was associated with reduced risk of ovarian carcinoma, supporting its role as a primary prevention strategy.

Abstract INTRODUCTION: Pleuropulmonary blastoma (PPB) and Sertoli-Leydig cell tumor (SLCT) are DICER1-related tumors for which novel therapies are urgently needed. A subset of Wilms tumors are also associated with germline or somatic variants in DICER1. Current therapies include cytotoxic chemotherapy, radiation, and surgery, but there are limited options for patients with recurrent disease. Antibody-Drug Conjugates (ADC) have emerged as promising therapies for several solid tumors. Aberrantly expressed cell surface proteins, including Preferentially Expressed Antigen in Melanoma (PRAME), represent potential targets for immunotherapeutic treatments like CAR-T cell and antibody-based therapies in malignant cancers, including DICER1-associated tumors. METHODS: Individuals diagnosed with PPB, SLCT, and Wilms tumor who enrolled in the International PPB/DICER1 Registry, International OTST Registry, and/or UT Southwestern Pediatric Hematology-Oncology Biorepository were selected for analysis. We analyzed ten PPB samples (four PDX, six primary tumor), four SLCT samples (all primary tumor), and 54 Wilms tumor samples (4 PDX, 50 primary tumor). DICER1 hotspot variants were verified in all 14 PPB and SLCT samples, while none of the Wilms tumor samples we analyzed exhibited DICER1 hotspot variants. Mapped and normalized whole-transcriptome sequencing reads were used to examine expression of 73 targets of antibody- or cell-based therapies that are clinically approved or under clinical investigation on clinicaltrials.gov. Genes with a median expression exceeding 2.5 transcripts per million (TPM) were considered expressed in a given tumor type; this threshold was selected to be permissive in identifying potential targets for further evaluation. RESULTS: Of the 73 genes of interest, 21 targetable cell-surface genes met a median expression threshold of 2.5 TPM in at least one tumor type: 11 genes in PPB, 16 in SLCT, and 14 in Wilms. Seven genes (FN1, PRAME, MCAM, CD248, IL11RA, CD276 (B7-H3), and MRC2) were expressed at this level in all three tumor types. Additional genes were expressed above this level in only two of the tumor types; PDGFRA in PPB and SLCT; GPC2 and TYRO3 in SLCT and Wilms tumor; and CSPG4, ERBB2, FZD10 in PPB and Wilms tumor. Six genes were exclusively expressed in SLCT (AXL, GPNMB, PROM1, KDR, ITGA6, FGFR4), and two were unique to Wilms tumor (GPC1, ULBP3). Of these, PRAME was previously reported as frequently expressed in DICER1-associated tumors; little has been reported about the remaining potential targets. CONCLUSION: PPB, SLCT, and Wilms tumor express several potential immunotherapy targets by RNA-seq. Expression of these potential targets should be investigated by immunostaining in a wider panel of tumors. Further study on the potential for ADCs or CAR-T cell therapies to treat DICER1-related conditions is needed. Citation Format: Brenya McNally, BS, Paige H.R. Mallinger, MS, David Huntsman, MD, FRCPC, FCCMG, Yemin Wang, PhD, Joyce Zhang, PhD, Claudette R. Fraire, PhD, Peter J. Schoettler, MD, Kris Ann P. Schultz, MD, Kenneth S. Chen, MD. Identifying potential cell-surface targets for therapeutic treatment of DICER1-related cancers [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Breaking Barriers in the Fight against Rare Cancers; 2026 Jul 18-20; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2026;86(14_Suppl):Abstract nr A018.