Pretreatment insights into primary sarcoma tissues using a novel approach of ex-vivo functional profiling to quantify cytotoxic and anti-proliferative effects of chemo and targeted therapies.

e23529 Background: Sarcoma treatment relies on doxorubicin- or ifosfamide-based regimens, or combinations like gemcitabine and docetaxel. While genomic testing and other biomarkers can sometimes guide targeted therapies, in many sarcoma cases, functional profiling of ex-vivo tumor tissue might be the only way to personalize cancer treatment. To do so, we developed a multi-dimensional profiling platform to quantify cytotoxic and cytostatic effects of NCCN-recommended therapies on fresh sarcoma specimens. Methods: Fresh sarcoma tissues from five patients were shipped on a cooled supply chain, processed within 24 hours, and 3D-cultured to mimic the patient's tumor microenvironment. Samples were treated with NCCN-recommended therapies at sub-pharmacologic to supra-pharmacologic concentrations for three days. Drug efficacy was assessed via metabolic and image-based 3D analyses, measuring 50% reductions (EC50s) in tumor viability (cytotoxicity) and proliferation (cytostatic effects), and patient reports were issued to the oncologist within 7-10 days. Results: EC50 values for both effects were measured for up to 30 drugs across five patients, varying by over two orders of magnitude. Anti-proliferative EC50s were typically over an order of magnitude lower than cytotoxic EC50s. While drugs like gemcitabine, sorafenib, and sunitinib were presumed to be more cytostatic, and platinum agents, actinomycin, and lurbinectedin were presumed more cytotoxic, actual ratios of those EC50 responses varied widely. These differences did not align with drug classes or presumed mechanisms of action, underscoring sarcoma heterogeneity and the limitations of relying solely on biomarkers or single-dimensional drug response data. Conclusions: This is the first study systematically comparing ex vivo anti-proliferative and cytotoxic profiles in live sarcoma tissues. Conventional chemosensitivity assays focusing on just one endpoint may oversimplify treatment decisions, whereas multi-dimensional functional profiling offers a more rational approach to personalized sarcoma therapy. Standardized EC50 for cytotoxicity and antiproliferation for NCCN guideline recommended therapies. Cytotoxicity Cytotoxicity Antiproliferation Antiproliferation Ratio Average St. Dev Average St. Dev Actinomycin 1.0 54.0 0.18 2.81 5.5 Carboplatin 65.9 2.1 1.92 31.43 34.4 Cytoxan 34.2 6.4 9.18 3.57 3.7 Docetaxel 24.9 11.1 4.13 32.61 6.0 Doxorubicin 40.0 2.3 3.65 22.81 10.9 Etoposide 83.0 1.5 5.37 31.62 15.5 Gemcitabine 9.4 26.0 0.91 7.13 10.3 Ifosfamide 0.7 6.4 0.30 6.92 2.4 Lurbinectedin 3.3 20.0 1.59 38.64 2.1 Topotecan 10.0 54.0 4.85 34.20 2.1 Vincristine 6.8 13.0 13.16 33.55 0.5