Abstract 3090: Patient derived cancer organoids predict clinical response for patients with locally advanced rectal cancer

Background: Locally advanced rectal cancer (LARC) is a common disease in the US, with a growing incidence in younger patients. These patients undergo multimodality treatments including chemotherapy, radiation, and surgery. For some patients this is likely over-treatment, while other patients require further treatment escalation. To date there is no clinical tool to know the potential benefit of these individual therapies. Patient-derived cancer organoids (PDCOs) are beginning to be evaluated for use as a means to predict individual patient response to clinical therapies. Here we use PDCOs from patients with LARC to compare the PDCO response to the individual clinical response.

Methods: Fresh LARC tissues from patients undergoing an endoscopy and tattooing procedure were obtained following consent on an IRB-approved protocol. PDCOs were cultured in using Matrigel and our previously published CRC organoids media. Following culture maturation, PDCOs were treated with control media, 5uM 5FU, 10uM Oxaliplatin, Combination (FOLFOX), XRT (2Gy) or 5FU and XRT. Brightfield imaging was performed at baseline and following 96 hours of treatment. Glass’s delta is used as a measure of the organoid treatment effect. A Glass’s delta of 1.25 was used as a threshold of treatment response based on prior studies. Clinical imaging was evaluated using standard RECIST v1.1 criteria of the objective response.

Results: Endoscopic LARC biopsy samples were obtained from 22 patients. 11 of the 22 samples were able to be grown as PDCOs. To date 9 cultures have been treated with FOLFOX and 9 have been treated with 5FU and XRT. For those treated with FOLFOX, 3/9 had a Glass’s delta greater than 1.25 and all of these patients has a clinical partial response (PR). None of those patients’ whose PDCOs did not achieve a Glass’s delta of at least 1.25 had a PR to FOLFOX clinically. No PDCO’s treated with 5FU and XRT achieved a Glass’s delta of >1.25. 3/9 PDCOs had a Glass’s delta >1.0. All of these patients had a PR. Of the 7 patients whose PDCOs did not achieve a Glass’s delta of 1 in response to 5FU and XRT, none had a clinical PR (Glass’s delta range 0.6-0.93).

Conclusion: PDCOs hold great promise as a tool to predict clinical outcomes for patients with LARC. Further evaluations need to establish improved methods of PDCO generation from biopsy samples and confirm the optimum response thresholds for prediction of treatment response.

Citation Format: Shirsa Udgata, Aishwarya Sunil, Rebecca L. Schmitz, Barsha Pantha, Amani Gillette, Jeremy Kratz, Patrick Grogan, Rebecca DeStefanis, Katherine Johnson, Sean Kraus, Evie Carchman, Elise Lawson, Christina Sanger, Charles Heise, Michael Bassetti, Randall Kimple, Kayla Lemmon, Morgan Larson, Cheri Pasch, Melissa Skala, Dustin Deming. Patient derived cancer organoids predict clinical response for patients with locally advanced rectal cancer [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 3090.

THSB2 as a prognostic biomarker for patients diagnosed with metastatic pancreatic ductal adenocarcinoma

Patients newly diagnosed with metastatic pancreatic ductal adenocarcinoma generally have poor survival, with heterogeneous rates of progression. Biomarkers that could predict progression and/or survival would help inform patients and providers as they make care decisions. In a previous retrospective study, we discovered that circulating thrombospondin-2 (THBS2) could, in combination with CA19-9, better distinguish patients with PDAC versus healthy controls. Here we evaluated whether THBS2 levels, previously not known to be prognostic, were associated with outcome in 68 patients at time of diagnosis of metastatic PDAC. Specifically, we interrogated the association of THBS2 level, alone or in combination with CA19-9, with progression by 90 days and/or survival to 180 days. The results indicate that elevated THBS2 levels alone, at the time of a metastatic PDAC diagnosis, can identify patients with a shorter time to death and thus help patients and providers when planning treatment.

THBS2/CA19-9 Detecting Pancreatic Ductal Adenocarcinoma at Diagnosis Underperforms in Prediagnostic Detection: Implications for Biomarker Advancement

Pancreatic ductal adenocarcinoma (PDAC) is often diagnosed too late for effective therapy. The classic strategy for early detection biomarker advancement consists of initial retrospective phases of discovery and validation with tissue samples taken from individuals diagnosed with disease, compared with controls. Using this approach, we previously reported the discovery of a blood biomarker panel consisting of thrombospondin-2 (THBS2) and CA19-9 that together could discriminate resectable stage I and IIa PDAC as well as stages III and IV PDAC, with c-statistic values in the range of 0.96 to 0.97 in two phase II studies. We now report that in two studies of blood samples prospectively collected from 1 to 15 years prior to a PDAC diagnosis (Mayo Clinic and PLCO cohorts), THBS2 and/or CA19-9 failed to discriminate cases from healthy controls at the AUC = 0.8 needed. We conclude that PDAC progression may be heterogeneous and for some individuals can be more rapid than generally appreciated. It is important that PDAC early-detection studies incorporate high-risk, prospective prediagnostic cohorts into discovery and validation studies.Prevention Relevance: A blood biomarker panel of THBS2 and CA19-9 detects early stages of pancreatic ductal adenocarcinoma at diagnosis, but not when tested across a population up to 1 year earlier. Our findings suggest serial sampling over time, using prospectively collected samples for biomarker discovery, and more frequent screening of high-risk individuals.