Abstract Background: Despite standard platinum-based doublet therapy, most patients with advanced ovarian cancer do eventually relapse1, and subsequent therapies exhibit variable benefit. Functional precision assays can guide treatment selection and reduce exposure to ineffective therapies. Here we used a multiplexed 3D functional profiling platform on specimens collected before and after neoadjuvant treatment, capturing evolving cytotoxic and antiproliferative responses and identifying effective treatment options. Methods: Fresh specimens were obtained from a patient with high-grade serous ovarian carcinoma: a baseline ascites sample from stage III disease, and a surgical biopsy sample collected at stage IV disease after neoadjuvant carboplatin-paclitaxel treatment. Specimens were processed to obtain ex-vivo microtumors2 and exposed to NCCN-recommended therapies. After 4 days of drug exposure, multiplexed viability and proliferation profiling was performed3. Four-parameter logistic dose-response curves were fitted, and differences (Δ) in cytotoxic and antiproliferative efficacies at standardized drug concentrations between the baseline and post-treatment samples were calculated. Results: The carboplatin paclitaxel combination showed moderate cytotoxic (0.37, estimated 95% CI 0.34-0.41) and antiproliferative effects (0.37 0.36-0.39) before and after neo-adjuvant treatment (0.30 0.25-0.36 and 0.33 0.31-0.36), aligning with the limited objective tumor response. VAC (vincristine, actinomycin, and cyclophosphamide) demonstrated high cytotoxic and antiproliferative efficacy before (0.85, 0.75-0.90, and 0.97 0.92-0.99) and after therapy (0.73 0.64-0.78, and 0.99 0.94-1.00). Interestingly, the PARP-inhibitors olaparib and rucaparib showed limited cytotoxicity (0.10 0.08-0.12 and 0 0-0.08) but pronounced antiproliferation (0.60 0.53-0.70 and 0.58 0.49-0.74) before the treatment with no material change after it. Conclusions: Sequential ex-vivo multiplexed profiling of this advanced ovarian cancer revealed that neoadjuvant carboplatin paclitaxel minimally altered cytotoxic and antiproliferative drug response sensitivity and resistance patterns to VAC and PARP inhibitors. Thus, pre-treatment functional profiling, when tumor tissue is readily available, might provide useful follow-on treatment options to avoid exposure to ineffective regimens in the future. 1 Pignata S et al., Treatment of recurrent ovarian cancer. Ann Oncol. 2017 2 Apfel C. Preparation of cells, cell aggregates and tissue fragments. Published October 2014 3 Apfel C et al., High-throughput multiplexed sensitivity and resistance assay. US Patent US 12,312,631 B1 Citation Format: Chiara Maestri, Ivan Trus, Rajeshwar Nitiyanandan, Ricardo J. Parker, Chris Apfel, . Sequential 3D functional profiling shows preserved drug resistance and sensitivity profiles after neoadjuvant treatment in an ovarian cancer patient abstract. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 7527.
Maestri et al. (Fri,) studied this question.