Abstract 162: Individualizing treatment using patient derived organoids, BH3 profiling and microfluidics: A proof of concept in a patient with low-grade serous ovarian carcinoma

Background N of 1 treatment paradigms represent the pinnacle of personalized medicine in which a patient’s tumors are profiled to guide treatment. Low-grade serous ovarian cancer (LGSC) is a distinct subtype of ovarian cancer, comprising ~10% of serous carcinomas and typically characterized by a younger age of onset. Molecularly, these tumors are often characterized by alterations within the Ras signaling pathway, including KRAS mutations. Clinically, LGSC is often resistant to standard cytotoxic chemotherapy, but may have sensitivity to hormonal therapy or MEK inhibitors. Here we report on a platform and proof of concept in one LGSC patient to evaluate personalized tumor-directed therapy regimens using patient-derived organoids (PDOs), BH3 profiling and viability evaluation in 3D microfluidic devices.

Methods A patient with LGSC presented to the Dana Farber Cancer Institute and was treated with carboplatin and paclitaxel before a total abdominal hysterectomy with a bilateral salpingo-oophorectomy. Tissue was obtained under an IRB approved protocol and PDOs were established. Standard of care and non-standard of care treatments including doxorubicin, abemaciclib, letrozole, alpelisib, tamoxifen, trametinib, venetoclax, and navitoclax were evaluated by two orthogonal assays. First, they were tested for delta priming by BH3 profiling (Bhola et.al., Sci Signal. 2020 ) and second for cell viability using 3D microfluidic devices by TMRM/DRAQ7 dual-color fluorescent staining. Standard of care treatments carboplatin and paclitaxel were evaluated as individual treatments and in combination in 3D microfluidic devices.

Results We successfully established a PDO model from the patient’s tumor sample in 14 days. BH3 profiling at 24 hours and viability in 3D microfluidic devices after 6 days in treatment showed that from the eight tested drugs, the model was sensitive to navitoclax and venetoclax. Average percent change in viability was -91.5% and -89.9%, respectively, and the drugs had a dynamic BH3 profiling index of 551.4 AUC (+/- 76.63) and 488.9 AUC (+/- 21.46) with the threshold of response being >175 for BH3 profiling. Trametinib showed a clear response in 3D, with an average percent change of -72.6% compared to the control but no significant response in BH3 profiling. Neither carboplatin and paclitaxel alone, nor in combination, elicited a significant change in viability. This observation was consistent with the patient’s history prior to surgery, where the tumor did not demonstrate significant clinical response to neoadjuvant carboplatin and paclitaxel therapy.

Conclusions We describe a proof of concept of a N of 1 response assessment platform for LGSC using PDOs, BH3 profiling and live/dead fluorescent staining in microfluidic devices and demonstrate that BH3 profiling and 3D viability assessment assays show good congruity.

Citation Format: Brittany Meisenheimer, Ha V. Vo, Kelley E. McQueeney, Aisha L. Saldanha, Carina Feeney, Courtney H. Qi, Swati Narayan, Jennifer D. Curtis, Marisa R. Nucci, Anthony Letai, Cloud P. Paweletz, Joyce F. Liu, Ursula A. Matulonis, Elena Ivanova. Individualizing treatment using patient derived organoids, BH3 profiling and microfluidics: A proof of concept in a patient with low-grade serous ovarian carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 162.

Abstract 3065: Establishment and characterization of a platform of endometrial cancer organoids

Background: Endometrial cancer is the most commonly diagnosed gynecologic cancer in the US; the incidence is rising, and survival rates for this cancer are decreasing. There is a paucity of effective treatment for recurrent endometrial cancer, especially high grade endometrial cancers (HGEC) which include serous, carcinosarcoma, endometrioid, and clear cell histologies. Models that mimic the clinical and molecular characteristics of HGEC are lacking. To support the development of next generation therapeutics for endometrial cancer, we report on the establishment of 3D endometrial patient-derived organoids (PDOs) from HGEC.

Methods: 26 Tumors from 21 different patients with HGEC (Serous, Carcinosarcoma, Clear Cell and High-grade Endometrioid subtypes) who underwent surgical resection (n= 13), biopsy (n = 7), paracentesis (n = 3) or thoracentesis (n = 3) were passaged as 3D organoid cultures in Matrigel in an optimized media. Robust models (defined by average days to passage <14 days) were viably banked. 3 frozen models were also thawed and re-cultured to assess the viability post freezing. PDOs were collected for H&E staining and their histology was compared to the original diagnosis. DNA replication rate and the effect of replication stress on organoid growth were assessed by the DNA Fiber Assay and immunofluorescence (IF). Finally, an established clear cell endometrial cancer organoid model was engrafted in mice to generate a Patient-Derived Xenograft (PDX) model.

Results: Endometrial PDOs were successfully developed from 19 of 26 original samples for an overall success rate of 73.1%. Successful PDOs were developed from multiple histologies, including 8 carcinosarcoma, 6 uterine serous, 2 endometrioid, 2 clear cell and 1 mixed uterine serous and endometrioid. Though biopsy samples had initially fewer viable cells, our overall success rate was similar at 85.7% compared to 84.6% for surgical resections and higher than 66.7% for paracenteses. Samples obtained via thoracentesis did not form PDOs. Endometrial PDOs were histologically validated to match the primary patient tumor. Freeze thawing had no effect on morphology and growth characteristics. DNA fiber assays could be successfully conducted in PDOs, with a reduction in replication rate observed in PDO models treated with ATR or WEE1 inhibitors, with concurrent increase in y-H2AX and decrease in pRPA2 observed by IF. We also successfully generated a validated PDX model from organoids. Studies to determine molecular fidelity between the original patient tumor and established organoids are ongoing.

Conclusions: We describe the successful establishment of 19 endometrial PDO models which retain original tumor morphology and demonstrate sensitivity to drug-induced DNA damage. 3D endometrial organoids can therefore be used for further target discovery and validation as well as biomarker studies to advance targeted therapies for high-grade endometrial cancer.

Citation Format: Aisha L. Saldanha, Ha V. Vo, Kevin Vasquez, Kenneth Ngo, Shrabasti Roychoudhury, Carina Feeney, Courtney H. Qi, Swati Narayan, Jennifer D. Curtis, Prafulla C. Gokhale, Dipanjan Chowdhury, Cloud P. Paweletz, Marisa R. Nucci, Ursula A. Matulonis, Elena Ivanova, Joyce F. Liu. Establishment and characterization of a platform of endometrial cancer organoids [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3065.