Liquid Biopsy for Detection of Pancreaticobiliary Cancers by Functional Enrichment and Immunofluorescent Profiling of Circulating Tumor Cells and Their Clusters

Circulating tumor cells (CTCs) have historically been used for prognostication in oncology. We evaluate the performance of liquid biopsy CTC assay as a diagnostic tool in suspected pancreaticobiliary cancers (PBC). The assay utilizes functional enrichment of CTCs followed by immunofluorescent profiling of organ-specific markers. The performance of the assay was first evaluated in a multicentric case-control study of blood samples from 360 participants, including 188 PBC cases (pre-biopsy samples) and 172 healthy individuals. A subsequent prospective observational study included pre-biopsy blood samples from 88 individuals with suspicion of PBC and no prior diagnosis of cancer. CTCs were harvested using a unique functional enrichment method and used for immunofluorescent profiling for CA19.9, Maspin, EpCAM, CK, and CD45, blinded to the tissue histopathological diagnosis. TruBlood® malignant or non-malignant predictions were compared with tissue diagnoses to establish sensitivity and specificity. The test had 95.9% overall sensitivity (95% CI: 86.0-99.5%) and 92.3% specificity (95% CI: 79.13% to 98.38%) to differentiate PBC (n = 49) from benign conditions (n = 39). The high accuracy of the CTC-based TruBlood test demonstrates its potential clinical application as a diagnostic tool to assist the effective detection of PBC when tissue sampling is unviable or inconclusive.

Accurate prostate cancer detection based on enrichment and characterization of prostate cancer specific circulating tumor cells

BACKGROUND

The low specificity of serum PSA resulting in the inability to effectively differentiate prostate cancer from benign prostate conditions is a persistent clinical challenge. The low sensitivity of serum PSA results in false negatives and can miss high-grade prostate cancers. We describe a non-invasive test for detection of prostate cancer based on functional enrichment of prostate adenocarcinoma associated circulating tumor cells (PrAD-CTCs) from blood samples followed by their identification by immunostaining for pan-cytokeratins (PanCK), prostate specific membrane antigen (PSMA), alpha methyl-acyl coenzyme-A racemase (AMACR), epithelial cell adhesion molecule (EpCAM), and common leucocyte antigen (CD45).

METHODS

Analytical validation studies were performed to establish the performance characteristics of the test using VCaP prostate cancer cells spiked into healthy donor blood (HDB). The clinical performance characteristics of the test were evaluated in a case-control study with 160 known prostate cancer cases and 800 healthy males, followed by a prospective clinical study of 210 suspected cases of prostate cancer.

RESULTS

Analytical validation established analyte stability as well as acceptable performance characteristics. The test showed 100% specificity and 100% sensitivity to differentiate prostate cancer cases from healthy individuals in the case control study and 91.2% sensitivity and 100% specificity to differentiate prostate cancers from benign prostate conditions in the prospective clinical study.

CONCLUSIONS

The test accurately detects PrAD-CTCs with high sensitivity and specificity irrespective of stage, serum PSA or Gleason score, which translates into low risks of false negatives or overdiagnosis. The high accuracy of the test could offer advantages over PSA based prostate cancer detection.

Multi-analyte liquid biopsies for molecular pathway guided personalized treatment selection in advanced refractory cancers: A clinical utility pilot study

Purpose

The selection of safe and efficacious anticancer regimens for treatment of patients with broadly refractory metastatic cancers remains a clinical challenge. Such patients are often fatigued by toxicities of prior failed treatments and may have no further viable standard of care treatment options. Liquid Biopsy-based multi-analyte profiling in peripheral blood can identify a majority of drug targets that can guide the selection of efficacious combination regimens.

Patients and methods

LIQUID IMPACT was a pilot clinical study where patients with advanced refractory cancers received combination anticancer treatment regimens based on multi-analyte liquid biopsy (MLB) profiling of circulating tumor biomarkers; this study design was based on the findings of prior feasibility analysis to determine the abundance of targetable variants in blood specimens from 1299 real-world cases of advanced refractory cancers.

Results

Among the 29 patients in the intent to treat (ITT) cohort of the trial, 26 were finally evaluable as per study criteria out of whom 12 patients showed Partial Response (PR) indicating an Objective Response Rate (ORR) of 46.2% and 11 patients showed Stable Disease (SD) indicating the Disease Control Rate (DCR) to be 88.5%. The median Progression-Free Survival (mPFS) and median Overall Survival (mOS) were 4.3 months (95% CI: 3.0 - 5.6 months) and 8.8 months (95% CI: 7.0 - 10.7 months), respectively. Toxicities were manageable and there were no treatment-related deaths.

Conclusion

The study findings suggest that MLB could be used to assist treatment selection in heavily pretreated patients with advanced refractory cancers.

Accurate Screening for Early-Stage Breast Cancer by Detection and Profiling of Circulating Tumor Cells

BACKGROUND

The early detection of breast cancer (BrC) is associated with improved survival. We describe a blood-based breast cancer detection test based on functional enrichment of breast-adenocarcinoma-associated circulating tumor cells (BrAD-CTCs) and their identification via multiplexed fluorescence immunocytochemistry (ICC) profiling for GCDFP15, GATA3, EpCAM, PanCK, and CD45 status.

METHODS

The ability of the test to differentiate BrC cases (N = 548) from healthy women (N = 9632) was evaluated in a case-control clinical study. The ability of the test to differentiate BrC cases from those with benign breast conditions was evaluated in a prospective clinical study of women (N = 141) suspected of BrC.

RESULTS

The test accurately detects BrAD-CTCs in breast cancers, irrespective of age, ethnicity, disease stage, grade, or hormone receptor status. Analytical validation established the high accuracy and reliability of the test under intended use conditions. The test detects and differentiates BrC cases from healthy women with 100% specificity and 92.07% overall sensitivity in a case-control study. In a prospective clinical study, the test shows 93.1% specificity and 94.64% overall sensitivity in differentiating breast cancer cases (N = 112) from benign breast conditions (N = 29).

CONCLUSION

The findings reported in this manuscript support the clinical potential of this test for blood-based BrC detection.

Response to pazopanib-based combination regimen in a case of FGFR3 amplified gastric adenocarcinoma

Angiogenesis inhibitors (AGI) are not presently used for the treatment of gastric cancers. This report demonstrates that angiogenesis inhibitor can be safely and effectively used in combination with cytotoxic anti-cancer agents for treatment of Gastric cancers.

Improved Treatment Outcomes by Using Patient Specific Drug Combinations in Mammalian Target of Rapamycin Activated Advanced Metastatic Cancers

Background: Activation of the mTOR signaling pathway is ubiquitous in cancers and a favourable therapeutic target. However, presently approved mTOR inhibitor monotherapies have modest benefits in labeled indications while poor outcomes have been reported for mTOR inhibitor monotherapy when administered in a label-agnostic setting based on univariate molecular indications. The present study aimed to determine whether patient-specific combination regimens with mTOR inhibitors and other anticancer agents selected based on multi-analyte molecular and functional tumor interrogation (ETA: Encyclopedic Tumor Analysis) yields significant treatment response and survival benefits in advanced or refractory solid organ cancers. Methods: We evaluated treatment outcomes in 49 patients diagnosed with unresectable or metastatic solid organ cancers, of whom 3 were therapy naïve and 46 were pre-treated in whom the cancer had progressed on 2 or more prior systemic lines. All patients received mTOR inhibitor in combination with other targeted, endocrine or cytotoxic agents as guided by ETA. Patients were followed-up to determine Objective Response Rate (ORR), Progression Free Survival (PFS) and Overall Survival (OS). Results: The Objective Response Rate (ORR) was 57.1%, the disease Control rate (DCR) was 91.8%, median Progression Free Survival (mPFS) was 4.9 months and median Overall Survival (mOS) was 9.4 months. There were no Grade IV treatment related adverse events (AEs) or any treatment related deaths. Conclusion: Patient-specific combination regimens with mTOR inhibition and other anti-neoplastic agents, when selected based on multi-analyte molecular and functional profiling of the tumor can yield meaningful outcomes in advanced or refractory solid organ cancers. Trial Registration: Details of all trials are available at WHO-ICTRP: https://apps.who.int/trialsearch/. RESILIENT ID CTRI/2018/02/011808. ACTPRO ID CTRI/2018/05/014178. LIQUID IMPACT ID CTRI/2019/02/017548.

Evaluation of circulating tumor cell clusters for pan-cancer noninvasive diagnostic triaging

BACKGROUND

Histopathologic examination (HPE) of tumor tissue obtained by invasive biopsy is the standard for cancer diagnosis but is resource-intensive and has been associated with procedural risks. The authors demonstrate that immunocytochemistry (ICC) profiling of circulating ensembles of tumor-associated cells (C-ETACs) can noninvasively provide diagnostic guidance in solid organ cancers.

METHODS

The clinical performance of this approach was tested on blood samples from 30,060 individuals, including 9416 individuals with known cancer; 6725 symptomatic individuals with suspected cancer; and 13,919 asymptomatic individuals with no prior diagnosis of cancer. C-ETACs were harvested from peripheral blood and profiled by ICC for organ-specific and subtype-specific markers relevant to the cancer type. ICC profiles were compared with HPE diagnoses to determine concordance.

RESULTS

The presence of malignancy was confirmed by the detection of C-ETACs in 91.8% of the 9416 individuals with previously known cancer. Of the 6725 symptomatic individuals, 6025 were diagnosed with cancer, and 700 were diagnosed with benign conditions; C-ETACs were detected in 92.6% of samples from the 6025 individuals with cancer. In a subset of 3509 samples, ICC profiling of C-ETACs for organ-specific and subtype-specific markers was concordant with HPE findings in 93.1% of cases. C-ETACs were undetectable in 95% of samples from the 700 symptomatic individuals who had benign conditions and in 96.3% of samples from the 13,919 asymptomatic individuals.

CONCLUSIONS

C-ETACs were ubiquitous (>90%) in various cancers and provided diagnostically relevant information in the majority (>90%) of cases. This is the first comprehensive report on the feasibility of ICC profiling of C-ETACs to provide pan-cancer diagnostic guidance with accuracy comparable to that of HPE.

Abstract PS2-40: Analytical and clinical validation of the trucheck™ platform for diagnostic triaging of symptomatic cases suspected of breast cancer

Background: trucheckTM is a non-invasive micro-biopsy-like approach for diagnostic triaging of symptomatic individuals suspected of Breast Cancer. trucheckTM is based on the detection of Circulating Ensembles of Tumor Associated Cells (C-ETACs: EpCAM+, Pan-CK+, CD45±) of Breast Cancer origin (GCDFP15+, GATA3+); such C-ETACs are ubiquitous in blood samples of patients with Breast Cancer and unexpected in asymptomatic individuals as well as in individuals with Benign Breast conditions. Methods: Analytical validation was performed using control cell lines for EpCAM (SKBR-3), Pan-CK (SKBR-3), CD45 (PBMCs), GCDFP15 (SKBR-3) and GATA3 (MCF-7) respectively. Known amounts of control cells were spiked into healthy donor blood and their recovery rates determined by immunocytochemistry (ICC) to establish Sensitivity, Specificity, Accuracy, Limit of Detection, Linearity and Precision. Clinical Validation was performed using 15 mL peripheral blood collected from 1,527 participants. An initial Retrospective Clinical Pre-validation was performed using blood samples collected from 547 known cases of Breast Cancer and 19 known cases of other (non-Breast) solid organ Cancers. In a subset of 20 Breast Cancer cases with metastases to the Lungs or Liver, C-ETACs were evaluated for markers associated Lung (Napsin-A, TTF-1, p40) and Liver (Hep-Par 1, Glypican-3) primaries. Prospective Clinical Validation was performed on blood samples collected prior to any invasive procedure from 961 symptomatic cases suspected of Breast Cancer. Results: Analytical Validation based on recovery of spiked control cells indicated 94.0% Sensitivity, 100% Specificity, 97.0% Accuracy, 93.2% - 96.7% Precision and significant linearity (R2≥0.99) for all ICC markers. Clinical Pre-validation indicated 89.4% Sensitivity and 100% Specificity. C-ETACs from the known Breast Cancer cases with Lung and Liver metastases were negative for Lung- and Liver-cancer specific ICC markers, respectively, while C-ETACs from non-Breast Cancer samples were negative for Breast Cancer-specific ICC markers. In the Prospective Clinical Validation, histopathological evaluation (HPE) of biopsied tumor tissue indicated Breast Cancer in 848 cases and benign conditions in 113 of the 961 suspected symptomatic cases. C-ETAC-based trucheckTM approach had 91.9% Sensitivity, 98.3% Specificity and 96.9% Accuracy. Conclusion: Analytical and Clinical Validation data establish the viability of C-ETAC-based trucheckTM for diagnostic triaging of symptomatic individuals suspected of Breast Cancer. Individuals positive for Breast Cancer-specific C-ETACs can be prioritized for further clinical procedures whereas C-ETAC negative individuals can be considered for alternate diagnoses.

Citation Format: Dadasaheb Akolkar, Darshana Patil, Pradip Fulmali, Pooja Fulmali, Revati Patil, Kiran Bendale, Archana Adhav, Shoeb Patel, Shabista Khan, Raja Dasarathan, Vishal Ranjan, Rohit Chougule, Pradyumna Shejwalkar, Akshay Ainwale, Mohini Garte, Rahul Sonawane, Madhav Purane, Yogeshwar Chaudhari, Prajakta Sagar, Shubhangi Nerkar, Vineet Datta, Cynthe Sims, Prashant Kumar, Ajay Srinivasan, Rajan Datar. Analytical and clinical validation of the trucheck™ platform for diagnostic triaging of symptomatic cases suspected of breast cancer [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS2-40.

Abstract PS3-13: Non-invasive screening for breast cancer risk based on circulating ensembles of tumor associated cells

Background: Common modalities for breast cancer screening include self-breast examination (SBE) for detection of palpable lumps as well as Mammography scans for detection of suspicious nodules or masses. While both approaches have low specificity, SBE has lower sensitivity for early stage cancers while mammography is associated with radiation exposure risks. A blood-based non-invasive approach for determination of breast cancer risk in asymptomatic individuals can facilitate early detection and improve prognosis and survival. Circulating Ensembles of Tumor Associated Cells (C-ETACs) are heterotypic clusters of malignant cells which originate in a tumor and are ubiquitously detected in peripheral blood of individuals with solid organ cancers. We present findings from two large-cohort prospective observational studies showing the suitability of C-ETACs for non-invasive, non-radiological screening for breast cancer. Methods: 15 ml of peripheral blood was collected from 14,962 female volunteers among whom 832 were suspected cases of breast cancer and 14,962 were asymptomatic individuals with age-associated risk of breast cancer. The 832 suspected cases underwent a foundational (first diagnostic) biopsy following collection of blood while the 14,962 asymptomatic individuals underwent a mammography scan following collection of blood. Peripheral blood mononuclear cells (PBMCs) were isolated from all blood samples and treated with an epigenetically activating treatment medium which exerts selective cytotoxicity towards non-malignant hematolymphoid cells and allows survival of apoptosis resistant malignant cells and their clusters (C-ETACs). C-ETACs were defined as clusters of 3 or more cells which were EpCAM+, PanCK+ and CD45+/-. Results: Among the 832 suspected cases, 779 were eventually diagnosed with breast cancer and 53 with benign breast conditions. C-ETACs were detected in 701 / 779 cases of breast cancer (90.0% sensitivity) with comparable detection rates in metastatic (365/408 = 89.5%) as well as non-metastatic (336/371 = 90.6%). C-ETACs were also detected in 1 / 53 (1.9%) cases of benign breast tumor. Among the asymptomatic cohort of 14,130, C-ETACs were detected in 657 cases (4.7%), which included 509 / 10,859 (4.7%) individuals with BIRADS 1 and in 148 / 3,271 (4.5%) of individuals with BIRADS ≥2. These individuals have been advised clinical follow-up. Conclusions: We show that C-ETACs are ubiquitous in breast cancers and rare in individuals with benign conditions as well as asymptomatic individuals. Being derived from the tumor mass, C-ETACs are specific for cancer and thus provide direct visual evidence of malignancy in cancer cases and risk of malignancy in asymptomatic cases. The non-invasive nature of the approach is well suited for screening of large asymptomatic populations for breast cancer.

Citation Format: Dadasaheb Akolkar, Darshana Patil, Pradip Fulmali, Pooja Fulmali, Revati Patil, Archana Adhav, Shoeb Patel, Sachin Apurwa, Sushant Pawar, Harshal Bodke, Vishal Ranjan, Rohit Chougule, Pradyumna Shejwalkar, Shabista Khan, Raja Dhasarathan, Pradip Devhare, Sanket Patil, Vineet Datta, Cynthe Sims, Stefan Schuster, Jatinder Bhatia, Chirantan Bose, Ajay Srinivasan, Rajan Datar. Non-invasive screening for breast cancer risk based on circulating ensembles of tumor associated cells [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS3-13.

Abstract PS4-36: Non-invasive evaluation of chemoresistance in breast cancers using circulating tumor associated cells

Background: Despite the development of Checkpoint Inhibitor Treatments (Immunotherapy) and Targeted anticancer agents, cytotoxic (chemotherapy) agents remain the mainstay of breast cancer treatments. However, treatment failure is often encountered in breast cancers owing to innate or acquired chemoresistance. Real time monitoring of inherent or incipient chemoresistance is an unmet need to minimize or prevent treatment failures and improve outcomes. However, prior efforts to determine chemoresistance have used tumor tissue or explants and are hence not suitable for repetitive monitoring. We present findings from a large cohort perspective observational study which shows that Circulating Tumor Associated Cells (CTACs) be isolated in sufficient numbers from peripheral blood and can be profiled in vitro for chemoresistance characteristics. Methods: 15 ml of peripheral blood was obtained from 1410 breast cancer patients, of whom 719 were treatment naïve and 691 had received prior systemic therapies. Matched tumor tissue was obtained by a biopsy (post-blood collection) in a subset of 68 cases. Peripheral blood mononuclear cells (PBMCs) were isolated from all blood samples and treated with an epigenetically activating treatment medium which exerts selective cytotoxicity towards non-malignant hematolymphoid cells and allows survival of apoptosis resistant malignant CTACs, which were defined as cells which were EpCAM+, PanCK+ and CD45+/-. Viable Tumor Derived Cells (TDCs) were harvested from biopsied tumor tissue (N=68). CTACs and TDCs were treated in vitro with cytotoxic chemotherapy agents that are used in Standard of Care (SoC) treatment protocols for breast cancer as single agents or in combinations. In 68 cases, concordance in Chemoresistance Profiles (CRP) was determined between CTACs and corresponding TDCs. In 681 pretreated cases, CRP of CTACs evaluated cumulative (innate and acquired) resistance following prior exposure to chemotherapy agents. In 685 therapy naïve cases, CRP of CTACs evaluated innate chemoresistance towards chemotherapy agents. Results: Among the 68 paired samples of CTACs and TDCs, there were 733 unique combinations of CTAC-TDC-drug, among which 366 pairs (50%) were concordant for chemo-resistance, 336 pairs (46%) were concordant for absence of resistance, and 31 pairs (4%) showed absence of concordance leading to a cumulative concordance of 96% in CRP between TDC and CTACs. Among the 681 pretreated cases, resistance towards ≥1 anticancer agents was observed in 67% of the samples. Among the 685 therapy naïve cases, resistance towards ≥1 anticancer agents was observed in 39% of the samples. Conclusion: The present study shows that sufficient CTACs can be harvested from peripheral blood for meaningful non-invasive chemoresistance profiling and that the resistance profiles of CTACs are concordant with that of tumor tissue. The present approach can identify innate as well as acquired chemoresistance and can guide selection of appropriate therapies. This approach can facilitate real time monitoring of chemoresistance and therapeutic course correction to minimize the risk of treatment failures.

Citation Format: Darshana Patil, Dadasaheb Akolkar, Sanket Patil, Vishakha Mhase, Sachin Apurwa, Sushant Pawar, Rutuja Bhave, Mahesh Ukade, Samruddhi Raut, Harshal Bodke, Shabista Khan, Raja Dhasarathan, Vineet Datta, Stefan Schuster, Cynthe Sims, Jatinder Bhatia, Chirantan Bose, Ajay Srinivasan, Rajan Datar. Non-invasive evaluation of chemoresistance in breast cancers using circulating tumor associated cells [abstract]. In: Proceedings of the 2020 San Antonio Breast Cancer Virtual Symposium; 2020 Dec 8-11; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2021;81(4 Suppl):Abstract nr PS4-36.

Development and validation of a multigene variant profiling assay to guide targeted and immuno therapy selection in solid tumors

We present data on analytical validation of the multigene variant profiling assay (CellDx) to provide actionable indications for selection of targeted and immune checkpoint inhibitor (ICI) therapy in solid tumors. CellDx includes Next Generation Sequencing (NGS) profiling of gene variants in a targeted 452-gene panel as well as status of total Tumor Mutation Burden (TMB), Microsatellite instability (MSI), Mismatch Repair (MMR) and Programmed Cell Death-Ligand 1 (PD-L1) respectively. Validation parameters included accuracy, sensitivity, specificity and reproducibility for detection of Single Nucleotide Alterations (SNAs), Copy Number Alterations (CNAs), Insertions and Deletions (Indels), Gene fusions, MSI and PDL1. Cumulative analytical sensitivity and specificity of the assay were 99.03 (95% CI: 96.54-99.88) and 99.23% (95% CI: 98.54% - 99.65%) respectively with 99.20% overall Accuracy (95% CI: 98.57% - 99.60%) and 99.7% Precision based on evaluation of 116 reference samples. The clinical performance of CellDx was evaluated in a subsequent analysis of 299 clinical samples where 861 unique mutations were detected of which 791 were oncogenic and 47 were actionable. Indications in MMR, MSI and TMB for selection of ICI therapies were also detected in the clinical samples. The high specificity, sensitivity, accuracy and reproducibility of the CellDx assay is suitable for clinical application for guiding selection of targeted and immunotherapy agents in patients with solid organ tumors.

A case report of androgen receptor inhibitor therapy in recurrent high-grade serous ovarian cancer

Ovarian cancer is common gynaecological malignancy and a leading cause of death among women. Despite the advances in treatment strategies, majority of patients present with recurrence after first- or second-line treatment. Targeted therapy that has proven to be effective in other advanced or metastatic solid tumors have also demonstrated its efficacy in ovarian cancer. Recent studies have shown that the androgen receptor (AR) signalling is involved in pathogenicity and progression of cancer. Current observations suggest AR could be a potential target in managing the disease. In this case report we present a patient with high grade serous ovarian cancer (HGSOC) with multiple relapses with excellent disease control on AR inhibition with bicalutamide.

Liquid biopsy and multi-analyte testing guided treatment of HER2 positive periampullary adenocarcinoma with durable complete response after trastuzumab based therapy

Periampullary adenocarcinomas are rare neoplasm that originates from the pancreatic head, the ampulla of vater, the distal bile duct or the duodenum. Surgical resection followed by adjuvant therapy is considered as the standard of care treatment for these carcinomas. Despite several advances in diagnostics and therapeutics, only 5% of these patients have an overall survival of five years or more. Currently, there is a dearth of viable therapeutic targets for this disease. The role of HER2 in cancer biology has been studied extensively in several tumour subtypes, and HER2 based targeted therapies have shown to have therapeutic benefits on different cancers. In this case report, we present a case of HER2 positive distal common bile duct carcinoma – a subtype of periampullary carcinoma with multiple relapses where multi-analyte testing with Encyclopedic Tumor Analysis (ETA) (Exacta^®) identified amplification and over expression of HER2 gene which was used as a potential target to treat the patient with trastuzumab. Synchronous in vitro chemosensitivity profiling on Circulating Tumor Asscociated Cells (C-TACs) isolated from blood aided us to design the personalized chemotherapeutic regimen with cyclophosphamide and methotrexate. The combination of trastuzumab with cyclophosphamide and methotrexate yielded excellent treatment response with the patient remaining in complete response till the last follow-up. Our study suggests HER2 directed therapy as a potent pathway for treatment in the subset of HER-2 amplified distal common bile duct carcinomas.

BIOM-35. MULTI ANALYTE ASSAY FOR NON-INVASIVE DIAGNOSIS OF BRAIN TUMORS

The diagnosis of Central Nervous System (CNS) malignancies such as Gliomas in individuals presenting with Intracranial Space Occupying Lesions (ICSOL) is based on histopathological examination (HPE) of tumor tissue obtained by an invasive brain biopsy. However, brain biopsies are resource intensive and are associated with procedural risks such as haemorrhage, morbidity and mortality. The present study evaluated a non-invasive approach for diagnosis of CNS-M in symptomatic individuals based on evaluation of circulating tumor analytes in peripheral blood. The non-invasive multi-platform approach for diagnosis of CNS-M included Immunocytochemistry (ICC) profiling and Fluorescence in situ Hybridization (FISH) of Circulating Tumor Cells (CTCs) and Digital Droplet PCR (ddPCR) of cell-free tumor DNA (ctDNA) and exosomal mRNA. Performance characteristics of each platform were evaluated using blood and tissue samples from 445 individuals including 227 known cases of CNS-M, 47 known cases of benign CNS conditions (CNS-B), 141 known cases of other cancers with brain metastases (OTH-M) and 30 asymptomatic individuals (ASYM). In a set of 37 samples from individuals with radiological ICSOL, suspected of malignancy (CNS-S) complete diagnostic work-up was performed with ICC, FISH and ddPCR. Glial CTCs were detected in 88.8% of 227 CNS-M and undetectable in 89.4% of 47 CNS-B or 100% of 141 OTH-M, indicating high sensitivity and specificity, respectively. The multi-analyte approach discerned CNS-M from CNS-B as well as OTH-M with 91.7% accuracy and accurately inferred lineage in 84.6% of cases. This non-invasive multi-analyte approach can diagnose CNS-M with an accuracy not inferior to standard HPE, can substitute invasive biopsies in most cases and is particularly helpful in cases where a biopsy is not viable.

Hallmark Circulating Tumor-Associated Cell Clusters Signify 230 Times Higher One-Year Cancer Risk

We have previously shown that circulating ensembles of tumor-associated cells (C-ETACs) are a systemic hallmark of cancer based on analysis of blood samples from 16,134 individuals including 10,625 asymptomatic individuals and 5,509 diagnosed cases of cancer. C-ETACs were ubiquitously (90%) detected across all cancer types and were rare (3.6%) among the asymptomatic population. Consequently, we hypothesized that asymptomatic individuals with detectable C-ETACs would have a definitively elevated risk of developing cancer as compared with individuals without C-ETACs. In the present manuscript we present 1-year follow-up data of the asymptomatic cohort which shows that C-ETAC positive individuals have a 230-fold (P < 0.00001) higher 1-year cancer risk as compared with individuals where C-ETACs were undetectable. Simultaneously, we also expanded the study to include 4,419 symptomatic individuals, suspected of cancer, prior to undergoing an invasive biopsy for diagnosis. C-ETACs were detected in 4,101 (92.8%) of these 4,419 cases where cancer was eventually confirmed. We conclude that detection of C-ETACs can identify patients at risk of cancer and can be reliably used to stratify asymptomatic individuals with an elevated 1-year risk of cancer. PREVENTION RELEVANCE: The study evaluated a blood test that can determine if healthy ('asymptomatic') individuals without a history of cancer have an increased risk of developing cancer within the next one year. This test can significantly minimize radiological or invasive screening in the majority individuals who do not have any increased risk.

Abstract B61: Encyclopedic noninvasive liquid biopsies for differential diagnosis in prostate cancer

Differential diagnosis of prostatic adenocarcinomas is based on histopathologic analysis of tumor tissue obtained by transrectal ultrasound (TRUS)-guided biopsies. However, such invasive biopsies are associated with pain, procedural expenses, sequelae, and risk of complications. Though immunocytochemistry (ICC) profiling of circulating tumor cells (CTCs, defined as EpCAM+, panCK+, CD45-) has been previously attempted for diagnosis in some cancers, it has been unviable due to limited yields of CTCs. For the first time we used enrichment of CTCs that permit meaningful ICC profiling for diagnosis of prostate cancers in suspected cases as contradistinguished from cases of benign enlargement of prostate (BEP). We obtained 15 mL of venous blood draw from 650 individuals, of whom 65 had a confirmed diagnosis of either prostate adenocarcinoma and 585 were diagnosed with benign prostate hyperplasia. CTCs were enriched from PBMCs fraction using an epigenetically acting enrichment process that is lethal towards normal (nonmalignant) cells but confers survival privilege on apoptosis-resistant CTCs. Harvested CTCs were confirmed by immunostaining for EpCAM and pan-CK. ICC profiling of these CTCs was also performed with organ-specific markers PSMA and AMACR. Viable CTCs could be obtained from 58 samples (89.2%) out of 65 confirmed prostate cancer cases. Among the 40 samples that were characterized by deep ICC profiling, all samples (100%) were positive for PSMA and AMACR. Among the benign cases, CTCs were observed in 10 samples (1.7%), of which all 10 were positive for PSMA but negative for AMACR. These patients are being followed up. Possibility of other cancers is not ruled out in these patients. Our results show that ICC-based characterization of CTCs can provide necessary diagnostic information noninvasively to substitute for conventional procedures dependent on tissue extraction.

Citation Format: Darshana A. Patil, Dadasaheb Akolkar, Revati Patil, Pooja Fulmali, Pradip Fulmali, Akshay Ainwale, Navin Srivastava, Vineet Datta, Cynthe Sims, Ajay Srinivasan, Rajan Datar. Encyclopedic noninvasive liquid biopsies for differential diagnosis in prostate cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B61.

Abstract A49: Viable circulating ensembles of tumor-associated cells persist in pretreated patients with solid organ cancers showing no radiologically detectable disease

The success of treatment in solid organ cancers is ascertained by radiologic imaging as per standard-of-care protocol, with PET-CT being the modality of choice. However, even in cases where complete resolution of the disease is noted radiologically, recurrence or emergence of new metastases is not uncommon. To explore the underlying cause of such recurrence, we hypothesized that circulating metastatic disease (CMD) in the nature of viable tumor cells or clusters would be a persistent systemic feature of solid organ cancers, although there may be no overt evidence of disease. We identified 1,217 patients with known and previously treated cases of various solid organ cancers (metastatic and nonmetastatic), where a recent PET-CT scan showed no radiologic evidence of disease. 15 mL peripheral blood was collected from these patients. Peripheral blood mononuclear cells (PBMCs) were harvested by centrifugation. Circulating ensembles of tumor-associated cells (C-ETACs) were enriched from PBMCs using an epigenetically acting stabilization process, which is cytotoxic towards nonmalignant cells but confers survival privilege on apoptosis-resistant cells of tumorigenic origin as well as their heterotypic clusters (C-ETACs). C-ETACs were characterized by immunostaining for EpCAM, pan-CK, and CD45 as well as for organ-specific markers. Among the 1,217 patients with no radiologic evidence of disease, C-ETACs were detected in 1,118 (91.9%) and were confirmed by immunostaining. In a subset analysis, C-ETACs from 80 samples were immunostained for organ- or subtype-specific antigens including those from head and neck (P63), breast (GCDFP15), colorectum (CDX2), liver (Hep Par-1), ovary (CA125), prostate (PSMA), cervical (P63), and lung (TTF-1/Napsin-A). Circulating metastatic disease (CMD) in the form of viable C-ETACs is a potent threat in patients with solid organ cancers despite complete radiologic response to treatment.

Citation Format: Sewanti A. Limaye, Timothy Crook, Dadasaheb Akolkar, Darshana Patil, Pradip Devhare, Revati Patil, Shoeb Patel, Shabista Khan, Raja Dhasarathan, Vineet Datta, Cynthe Sims, Ajay Srinivasan, Rajan Datar. Viable circulating ensembles of tumor-associated cells persist in pretreated patients with solid organ cancers showing no radiologically detectable disease [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr A49.

Abstract B17: An mRNA signature that accurately discerns gliomas from healthy individuals

Diagnosis of suspected cases of gliomas such as intracranial space-occupying lesions (ICSOLs) is based on histopathologic analysis of tumor tissue obtained by invasive biopsies, which are, however, associated with risk of serious complication, high rates of mortality, procedural expenses, sequelae, and other risks. Liquid biopsy (LB)-based noninvasive approaches for diagnosis of gliomas based on circulating tumor biomarkers in peripheral blood have hence gained considerable interest. We describe the discovery of a unique 20 exosomal mRNA signature that can discern gliomas from healthy individuals. We obtained 15 mL of peripheral blood by venous draw from 222 individuals, among whom 47 had confirmed diagnosis of gliomas and 175 were asymptomatic. Exosomes were enriched from peripheral blood and were used for isolation of mRNAs. Exosomal mRNAs were used for expression analysis of 20,802 gene transcripts, including 18,574 coding genes and 2,228 noncoding genes based on University of California Santa Cruz (UCSC) hg19 annotation. Differentially expressed mRNAs were analyzed using a machine learning algorithm to identify transcripts that were unique to or uniquely absent in known cases of gliomas and in healthy individuals. The machine learning algorithm identified a 20-mRNA signature that discerned gliomas from healthy individuals with high sensitivity (87%) and specificity (95%) with an overall accuracy of 94%. The differentially expressed transcripts included MST4, RARRES3, TARP, IL32, PPP3CC, RSL1D1, RSL24D1, EIF4B, ARHGEF3, DENND2D, EVL, SEC11A, RPL22L1, HIST1H1C, IRF8, SOS2, GLTSCR2, GIMAP7, HIST1H4D, and CDK11. These differentially expressed transcripts are potentially involved in various functions such as tumor suppression, protein phosphorylation-dephosphorylation, signal transduction (ligand binding), and cell cycle regulation. Our data indicate that exosomal mRNA profiling is a viable approach for discerning suspected cases of gliomas from healthy individuals. The noninvasive nature of this approach coupled with high sensitivity and specificity favor potential clinical application.

Citation Format: Sachin Apurwa, Pooja Fulmali, Dadasaheb Akolkar, Darshana Patil, Sushant Pawar, Sneha Puranik, Vipul Todarwal, Akshay Ainwale, Pradip Devhare, Vineet Datta, Cynthe Sims, Ajay Srinivasan, Rajan Datar. An mRNA signature that accurately discerns gliomas from healthy individuals [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B17.

Abstract B62: Wholesome non-invasive liquid biopsies for pharmacodiagnostic work-up in breast cancer

Background: Diagnosis and treatment of breast cancers is based on histopathological analysis of tumor tissue obtained by invasive biopsies. However invasive biopsies cause pain, anxiety and carry the risk of needle seeding. Though Immunocytochemistry (ICC) profiling of Circulating Tumor Cells (CTCs, defined as EpCAM+, panCK+, CD45-) has been previously attempted for diagnosis, these efforts have been unsuccessful. We used an epigenetically modified medium for enrichment of sufficient viable CTCs. These CTCs were used for diagnosis and characterization.

Methods: We obtained 15 ml of venous blood draw from 2500 patients with confirmed diagnosis of breast cancer. CTCs were enriched from PBMCs fraction using an epigenetically acting enrichment process that is lethal towards normal (non-malignant) cells, but confers survival privilege on apoptosis-resistant CTCs. Harvested CTCs were confirmed by immunostaining for EpCAM and pan-CK. Deep ICC profiling of these CTCs was performed with organ specific marker GCDFP15. Theranostic ICC Profiling was performed with ER and Her2.

Results: CTCs could be obtained from 2232 samples (89.3%) out of 2500. A subset of 100 samples were characterised by deep ICC profiling, among which 80% of samples were positive for GCDFP15. 14 and 17 samples out of 100 were positive for ER and Her2 respectively.

Conclusions: Our results show that ICC based characterization of CTCs can provide necessary diagnostic information non-invasively to substitute conventional procedures dependent on tissue extraction.

Citation Format: Dadasaheb Akolkar. Wholesome non-invasive liquid biopsies for pharmacodiagnostic work-up in breast cancer [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B62.

Abstract B15: Circulating tumor cells express tissue specific antigens in multiple cancers

Definitive diagnosis of solid organ cancers is based on histopathologic analysis of tumor tissue obtained by invasive biopsies. However, invasive biopsies are associated with procedural expenses, sequelae, and risks. Though immunocytochemistry (ICC) profiling of circulating tumor cells (CTCs) has been previously attempted for diagnosis in some cancers, they have been unviable due to limited yields of CTCs. We used a novel approach for enrichment of sufficient viable CTCs that permit meaningful ICC profiling for diagnosis of cancers in suspected cases. We obtained 15 mL of venous blood draw from 965 patients with confirmed diagnosis of various solid organ cancers. CTCs were enriched from PBMCs fraction using an epigenetically activated enrichment process that is lethal towards normal (nonmalignant) cells but confers survival privilege on apoptosis-resistant CTCs. Harvested CTCs were confirmed by immunostaining for EpCAM and pan-CK. Deep ICC profiling of these CTCs was performed with organ-specific marker for various organs such as lungs (TTF-1 or Napsin), breast (GCDFP15 or GATA3), ovarian (CA125 or WT-1), pancreatic (CK19 or CA19-9), cervical (P63), liver (Hep Par-1 or Glypican), colorectal (CK20 or CDX-2), head and neck (P63), kidney (Pax-8 or RCC), and prostate (PSMA or AMACR). CTCs (EpCAM+, pan-CK+) could be obtained from 94.4% of all samples. Organ-specific markers were positive in 100% of lung cancer, 79.3% of breast cancers, 70.0% of ovarian cancers, 93.3% of pancreatic cancers, 100% of cervical cancers, 61% of hepatocellular carcinomas, 92.6% ofcColorectal cancers, 98.8% of head and neck cancers, 100% of renal cancers, and 100% of prostate cancers. Our results show that deep ICC profiling of CTCs can determine tissue of origin in solid organ cancers noninvasively to substitute conventional procedures dependent on tissue extraction.

Citation Format: Dadasaheb Akolkar, Revati Patil, Darshana Patil, Pradip Fulmali, Pooja Fulmali, Shoeb Patel, Pradip Devhare, Akshay Ainwale, Vineet Datta, Cynthe Sims, Ajay Srinivasan, Rajan Datar. Circulating tumor cells express tissue specific antigens in multiple cancers [abstract]. In: Proceedings of the AACR Special Conference on Advances in Liquid Biopsies; Jan 13-16, 2020; Miami, FL. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(11_Suppl):Abstract nr B15.

Abstract P4-01-17: Viable circulating ensembles of tumor associated cells persist in patients with no radiologically detectable disease after treatment in breast cancer

Oncological orthodoxy holds that (metastatic) breast cancer is an incurable disease. Response evaluation in metastatic breast cancer is determined by clinical, biochemical and radiological parameters, FDG PET CT being the imaging modality of choice for most types of breast cancer. However, even in cases where FDG PET CT and/or normalisation of serum tumour markers imply complete response to systemic therapy, durable disease-free survival is uncommon. To explore the mechanistic basis underlying persistent disease in spite of apparently effective systemic therapy, we hypothesized that Circulating Metastatic Disease (CMD) in the form of viable tumor cells or clusters might be a feature of persisting breast cancer. To address this, we obtained 15ml of peripheral blood from 927 known and previously treated cases of breast cancers immediately prior to FDG PET CT restaging. Peripheral blood mononuclear cells (PBMCs) were harvested by centrifugation. Circulating Ensembles of Tumor Associated Cells (C-ETACs), which are clusters of heterotypic apoptosis resistant cells of tumorigenic origin were enriched by a novel process using a combination of commercially available stabilizing agents. C-ETACs were characterized by immunostaining for EpCAM, pan-CK and CD45 as well as GCDFP-15 or GATA3. 927 patients underwent FDG PET CT of whom 731 (78.9%) had evidence of FDG avid residual disease. 196 patients (21.1%) had no metabolically active disease, among whom C-ETACs were detected in 171/196 cases (87.2%). The presence of CMD in a high proportion of cases in patients with no evidence of metabolically active disease implies that the majority of patients in whom conventional parameters of disease are negative have residual disease and are not biologically cured.

Citation Format: Ajay Srinivasan, Dadasaheb Akolkar, Darshana Patil, Timothy Crook, Cynthe Sims, Revati Patil, Vineet Datta, Anantbhushan Ranade, Pradip Fulmali, Pradip Devhare, Pooja Fulmali, Shoeb Patel, Akshay Ainwale, Sneha Puranik, Rajan Datar. Viable circulating ensembles of tumor associated cells persist in patients with no radiologically detectable disease after treatment in breast cancer [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P4-01-17.

Abstract P6-10-11: In vitro chemo interrogation of viable circulating tumor associated cells from breast cancer patients

Background: Chemoresistance in cancer cells is the underlying reason for treatment failure. Real-time monitoring of chemoresistance and response (CRR) is a fundamental but unmet prerequisite of precision oncology. Repetitive invasive biopsies to obtain tumor tissue for in-vitro CRR profiling are neither feasible nor advisable. Circulating Tumor Associated Cells (C-TACs) have been proposed for functional assessment of CRR. In this observational study, we performed CRR profiling on viable C-TACs from breast cancer patients.

Methods: In this 3 arm study, viable C-TACs were harvested from 15 ml of peripheral blood obtained from 242 breast cancer patients using CellWizard™, an epigenetically active media with paradoxical cytotoxicity that selectively kills normal cells and simultaneously confers survival benefit on cells of tumorigenic origin. C-TACs were stained with EPCAM, CK, CD45 and GCDFP. Viable Tumor Derived Cells (TDCs) harvested from freshly biopsied tumor tissue (Arm 1, N=48) and concurrently obtained C-TACs were simultaneously CRR profiled irrespective of whether patient was pre-treated or otherwise. Arm 2 (N=100) included refractory (pre-treated) patients where C-TACs were evaluated for resistance to previously administered drugs. Arm 3 (N=124) included recently diagnosed therapy naïve patients where C-TACs were evaluated for innate chemoresistance.

Results: In Arm 1, CRR profile of C-TACs showed 96.1% concordance with CRR profile of concurrently obtained TDCs. In Arm2, CRR profiling of C-TACs identified chemoresistance due to prior drug exposure in 91.4% of patients. In Arm 3, innate chemoresistance was observed in 42% of patient samples towards commonly used first / second line Standard of Care drugs belonging to various functional categories such as mitotic inhibitors, DNA damaging agents, topo inhibitors and antimetabolites.

Conclusion: This study shows for the first time the feasibility of CRR profiling of C-TACs and its correlation to in-vitro and in-vivo CRR characteristics of the tumor. Adoption of C-TAC based CRR profiling can provide unprecedented real time treatment oversight towards treatment selection and monitoring of drug resistance for personalized treatment of breast cancer patients.

Citation Format: Timothy Crook, Dadasaheb Akolkar, Sanket Patil, Vishakha Mhase, Revati Patil, Cynthe Sims, Vineet Datta, Sachin Apurwa, Viwek Mane, Ashok Gawai, Madhavi Apastamb, Ajay Srinivasan, Rajan Datar. In vitro chemo interrogation of viable circulating tumor associated cells from breast cancer patients [abstract]. In: Proceedings of the 2019 San Antonio Breast Cancer Symposium; 2019 Dec 10-14; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(4 Suppl):Abstract nr P6-10-11.

Circulating ensembles of tumor-associated cells in gastrointestinal cancers

808

Background: CEA and CA19-9 are non-specific markers for Gastrointestinal (GI) cancers. Molecular analysis of fecal blood is of limited utility in colorectal cancers. A non-invasive pan-GI-cancer blood-based test with high specificity and sensitivity is an unmet medical need. Considering that unprovoked thromboembolism is a significant risk in multiple cancers, we hypothesized that circulating thrombotic emboli in peripheral blood could comprise cancer cells and would serve as a reliable biomarker for detection of GI cancers. Methods: We obtained 15ml of blood from 7481 individuals, including 181 cases of Esophageal cancer, 125 cases of Gastric cancer, 448 cases of colorectal cancer and from 6727 asymptomatic individuals with age related elevated risk who underwent evaluation of serum CA19-9 and AFP. Peripheral blood mononuclear cells (PBMC) were isolated by centrifugation and further processes for negative enrichment and harvesting of circulating tumor cell clusters which were characterized by immunostaining. Circulating Ensembles of Tumor Associated Cells (C-ETACs) were defined as clusters of 3 or more cells which were positive for EpCAM and CK, irrespective of CD45 status. Results: C-ETACs were detected in 86.7% of esophageal cancers, 94.4% of gastric cancers and 91.3% of colorectal cancers respectively irrespective of extent (stage / metastatic status) of disease and prior treatments. Overall sensitivity among 754 cancer patients was 90.7%. Among the asymptomatic individuals, C-ETACs were detected in 31 / 366 (8.5%) individuals with elevated CEA and 10 / 152 (6.2%) individuals with elevated CA19-9. C-ETACs were detected in 160 / 5333 (2.9%) of the asymptomatic individuals who had no abnormal findings in any of the said markers. Conclusions: C-ETACs were ubiquitously detected in cancers of Oesophagus, Stomach and Colorectum regardless of stage and treatment status, and pose significant latent risk of thromboembolism and metastasis/recurrence. The relative undetectability of C-ETACs in the asymptomatic cohort indicates causative connection with malignancies and are suitable for screening for these cancers.

Encyclopedic liquid biopsies for guideline-compliant diagnostic work-up in gastrointestinal cancers

799

Background: Definitive diagnosis of gastrointestinal (GI) malignancies is reliant on histopathological examination of tumor tissue obtained by invasive biopsies. However, invasive biopsies are associated with procedural risks, complications and expenses. A non-invasive technique for diagnosis of GI cancers is presently unavailable. Here we present a non-invasive diagnostic approach for GI cancers based on immunocytochemical (ICC) profiling of Circulating Tumor Associated Cells (C-TAC) enriched from peripheral blood. Methods: We collected 15 mL peripheral blood from 1052 patients with known diagnosis of Ca Oesophagus (244), Ca Stomach (170) and Ca Colorectum (638) and with histopathological information available from prior tissue analysis. CTACs were harvested following negative enrichment. C-TACs were identified by immunostaining with EpCAM and panCK. Deep ICC characterization was carried out in a subset of 203 samples (100 colorectal, 19 Gastric and 84 Esophageal) using organ specific markers. A subset of 19 samples from Gastric and 94 samples Esophageal cancers were profiled for Her2 and PD-L1 status. Results: C-TACs could be identified and enriched in 1012 out of 1052 patients (96.2% overall sensitivity). Immunostaining for organ-specific markers was possible in all 203 (100%) samples. Her2 positivity was observed in 2/19 Gastric and 19/84 Esophageal samples. PD-L1 (22C3) positivity was observed in 5/19 Gastric and 32/84 Esophageal samples while PD-L1 (28-8) positivity was observed in 2/19 Gastric and 16/84 Esophageal samples. Conclusions: Our results show that ICC profiling of C-TACs can provide necessary diagnostic information non-invasively to substitute conventional procedures dependent on tissue extraction. This approach fulfils most clinical decision-making requirements in GI malignancies.

Effect of previous chemotherapy treatments on circulating tumor-associated cells in colorectal cancer

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Background: Resistance to combination regimens of fluorouracil, oxaliplatin and irinotecan are commonly observed in Colorectal cancers (CRC). There are presently no viable approaches for ‘real-time’ monitoring of innate and acquired chemoresistance. We used a novel method for chemo-interrogation (CI) by harvesting from peripheral blood sufficient numbers of Circulating-Tumor Associated Cells (CTACs) which are defined as apoptosis-resistant cells of tumorigenic origin which are positive for Epithelial Cell Adhesion Molecule (EpCAM) and pan-cytokeratins (pan-CK) irrespective of CD45 status. Methods: Peripheral blood was collected from 110 patients with confirmed diagnosis of CRC, among whom 56 were recently diagnosed and therapy naïve while 54 were pre-treated. Peripheral blood mononuclear cells (PBMCs) were harvested by centrifugation and treated with commercially available stabilizing agents by a proprietary protocol to stabilize apoptosis resistant C-TACs. Surviving C-TACs were confirmed by immunostaining for EpCAM and pan-CK. Harvested C-TACs were treated in vitro with 5-fluorouracil, irinotecan and oxaliplatin and the fraction of surviving cells estimated to determine resistance profiles. Results: Among the 56 cases of recently diagnosed therapy naïve CRC, innate chemoresistance was observed in 37.5%, 47.3% and 41.8% of samples (unique patient-drug combinations) towards 5-fluorouracil, irinotecan and oxaliplatin respectively. Among the 54 cases of previously treated CRC, acquired chemoresistance was observed in 92.6%, 92.6% and 95.5% of samples towards 5-fluorouracil, irinotecan and oxaliplatin respectively. Conclusions: We show for the first time that sufficient C-TACs can be harvested for meaningful CI in newly diagnosed treatment naïve CRC as well as refractory CRCs. Post-treatment chemoresistance being an order of magnitude higher than the untreated cohort indicates that C-TACs in CRC are resistance-educated by previous treatments and can guide treatment strategy.

Circulating ensembles of tumor-associated cells: A redoubtable new systemic hallmark of cancer

Circulating ensembles of tumor‐associated cells (C‐ETACs) which comprise tumor emboli, immune cells and fibroblasts pose well‐recognized risks of thrombosis and aggressive metastasis. However, the detection, prevalence and characterization of C‐ETACs have been impaired due to methodological difficulties. Our findings show extensive pan‐cancer prevalence of C‐ETACs on a hitherto unreported scale in cancer patients and virtual undetectability in asymptomatic individuals. Peripheral blood mononuclear cells (PBMCs) were isolated from blood samples of 16,134 subjects including 5,509 patients with epithelial malignancies in various organs and 10,625 asymptomatic individuals with age related higher cancer risk. PBMCs were treated with stabilizing reagents to protect and harvest apoptosis‐resistant C‐ETACs, which are defined as cell clusters comprising at least three EpCAM⁺ and CK⁺ cells irrespective of leucocyte common antigen (CD45) status. All asymptomatic individuals underwent screening investigations for malignancy including PAP smear, mammography, low‐dose computed tomography, evaluation of cancer antigen 125, cancer antigen 19‐9, alpha fetoprotein, carcinoembryonic antigen, prostate specific antigen (PSA) levels and clinical examination to identify healthy individuals with no indication of cancer. C‐ETACs were detected in 4,944 (89.8%, 95% CI: 89.0–90.7%) out of 5,509 cases of cancer. C‐ETACs were detected in 255 (3%, 95% CI: 2.7–3.4%) of the 8,493 individuals with no abnormal findings in screening. C‐ETACs were detected in 137 (6.4%, 95% CI: 5.4–7.4%) of the 2,132 asymptomatic individuals with abnormal results in one or more screening tests. Our study shows that heterotypic C‐ETACs are ubiquitous in epithelial cancers irrespective of radiological, metastatic or therapy status. C‐ETACs thus qualify to be a systemic hallmark of cancer.

What's new?

Circulating Ensembles of Tumor Associated Cells (C‐ETACs) comprised of tumor emboli, immune cells, and fibroblasts pose well‐recognized risks of thrombosis and aggressive metastasis. However, the detection and characterization of C‐ETACs have been impaired by methodological difficulties. Here, the authors have developed a label‐free non‐mechanical process that permits enrichment of viable apoptosis‐resistant C‐ETACs from peripheral blood. They show that heterotypic C‐ETACs are not merely incidental findings in cancer but rather a systemic manifestation of malignancy. C‐ETACs are present in a significant proportion of all solid organ malignancies and are rare in asymptomatic individuals. Monitoring of C‐ETACs could help inform cancer management.

PATH-64. PROSPECTIVE, BLINDED PLASMA BASED ANALYSIS FOR DIAGNOSIS OF NEWLY DIAGNOSED GLIOMA

INTRODUCTION

In patients with newly diagnosed intracerebral lesions, gliomas are often suspected. However, other conditions such as multiple sclerosis, abscess or lymphoma are possible, as well. Furthermore, biopsy can be challenging due to eloquent and/or deep location within the brain. In this prospective, blinded study, analysis of plasma isolated cell-free DNA and exosome mRNA and miRNA from newly diagnosed glioma patients and from cancer-free volunteers was used to predict disease.

METHODS

Plasma was drawn from 52 patients with newly diagnosed gliomas (28 high grade glioma (HGG), 10 low grade (LGG)) and 14 patients without documented history of cancer and recent MRI brain which was negative for brain tumor. High quality DNA and RNA was isolated and sequenced using Next Generation Sequencing and Digital Droplet PCR was used for detection and verification of trace molecular artifacts. Multianalyte processing yielded data that was harmonized and interpreted through an Artificial Intelligence based algorithm to assess for possible glioma and to assign grade in a blinded fashion. EGFRvIII, TP53 and IDH1 mutations were also analyzed and compared to molecular testing from tumor specimens.

RESULTS

66% (25 of 38) of glioma patients were correctly diagnosed as having a malignancy. 43% of HGG and 60% of LGG patients were correctly graded. Of the 14 normal controls, 6 were concluded to be cancer-free. IDH1, EGFRvIII, and TP53 mutation had concordance of 64% (21/33), 82% (14/17) and 36% (5/14), respectively.

CONCLUSIONS

Analysis of plasma cell free tumor derived DNA and RNA was relatively sensitive for detecting glioma in treatment naïve patients. In contrast, this analysis was not specific in ruling out malignancy in the normal control patients. Given this profile, in patients with newly diagnosed intracerebral lesions suspicious for glioma, this may be a useful screening test to determine the need for more invasive testing, i.e. biopsy/resection.

CMET-37. CLINICAL UTILITY OF ENCYCLOPEDIC TUMOR ANALYSIS TO TREAT PATIENTS WITH BRAIN METASTASIS IN REFRACTORY CANCERS

Brain metastasis in solid organ cancers is associated with adverse prognosis, which is further aggravated by limited systemic treatment options. Such patients are also often excluded from clinical trials since their poor prognosis is perceived to unfavorably impact trial outcomes and misrepresent efficacy data. We retrospectively evaluated the efficacy of treatment guided by Encyclopedic Tumor Analysis (ETA) in patients with advanced refractory malignancies and brain metastases to determine the impact on outcomes. Freshly biopsied tumor tissue (primary / lymph node / liver) and peripheral blood of patients were used for integrational multi-analyte investigations as part of ETA, which included gene mutations, gene expression, and in vitro chemosensitivity profiling of viable tumor cells. Based on ETA, patients received individualized therapy recommendations. All patients underwent a PET-CT scan as well as MRI scan prior to treatment start to determine extent of disease. All patients underwent follow-up PET-CT scans and brain MRI scans every 6–8 weeks. Of the ten patients with brain metastases, which were evaluated after receiving ETA-guided treatment, the median follow-up duration was 97 days (range 79 – 180 days) during which all ten patients remained progression-free. Median time to progression for these patients on the last (failed) line of treatment was 91 days (range 30 - 176 days). Five patients showed partial response and five patients showed stable disease while on ETA-guided treatment. During the follow-up period, all brain metastases were either stable (n=7) or had regressed (n=3), and none of the patients reported new brain lesions. Personalized ETA guided treatments imparted clinical benefit by halting disease progression in this cohort of high-risk patients who would have otherwise been considered for palliative regimens due to perceived unfavorable prognosis.

INNV-26. IN VITRO CHEMO RESISTANCE PROFILES OF CIRCULATING GLIAL CELLS REPLICATE CHEMO CHARACTERISTICS OF TUMOR TISSUE

Survival of high-grade glioma patients remains dismal due to onset of resistance to even the limited systemic treatment option currently available. Except for indirect prediction of alkylating agent Temozolomide response through MGMT promotor methylation and NTRK fusions for larotrectinib, there are no biomarkers available for drug response prediction. Cell based, in vitro chemosensitivity assays can interrogate the efficacy of an array of cytotoxic drugs. However, the unavailability of live tumor cells for such assays pose challenges in clinical practice. Repeat biopsies are neither advisable nor feasible. Access to Circulating Glial Cells (CGCs) can provide real time insight into the chemo dynamics of the tumor. In this study, we show for the first time that CGCs can be harvested from peripheral blood of glioma patients for chemo response and resistance profiles (CRR) of cytotoxic drugs. CGCs were harvested from 15 ml of peripheral blood from high grade GBM patients (n=9) out of whom cells derived from surgically excised tumor tissue were also available for comparison in 2 patients. CellWizard™ process was adopted for enrichment of CGCs which is based upon epigenetically active media with paradoxical chemo-toxicity that selectively induces lethality in normal cells. This paradoxical cytotoxicity of the medium leads to selective elimination of most leukocytes thus facilitating a label free negative enrichment of CGCs. In vitro chemo sensitivity assay performed on live CGCs and cell death events were determined to evaluate response to different class of chemotherapy drugs. Evaluation of drug response showed very high concordance between tumor derived cells and CGCs in both patients where live tissue was available. In 7 patients where CGCs alone could be evaluated, the response showed replication between in vitro profile compared to treatment antecedents in 5 patients. 2 patients were treatment naïve and the response reflected high sensitivity to Temozolomide.

PATH-43. DIAGNOSIS OF GLIOMAS USING CIRCULATING GLIAL CELLS

Invasive procedures for diagnosis of CNS malignancies carry inherent risks of high morbidity and mortality. Although circulating biomarkers such as cell free DNA (cfDNA) and microvesicle (MV) borne nucleic acids have been proposed as potential diagnostic aids, their stand-alone utility has inherent limitations. However, Circulating Glial Cells (CGCs) combined with cfDNA could offer a viable alternative to invasive biopsies for diagnosis of CNS malignancies; yet the technological challenge in the detection of CGCs in glioma patients presents a formidable challenge. In this study, we evaluated the feasibility of harvesting CGCs from suspected cases of Glioma. From a cohort of 23 suspected cases of CNS malignancies, we used 15ml of peripheral blood and used the CellWizard™ process and related protocol for isolation of CGCs. CellWizard™ is an epigenetically active media with paradoxical chemo-toxicity that selectively induces lethality in normal cells which have a functionally responsive cell death (apoptosis) mechanism, while simultaneously conferring survival privilege on apoptosis resistant cells typically released from a malignant tumor. This paradoxical cytotoxicity of the medium leads to selective elimination of most leukocytes thus facilitating a label free negative enrichment of CGCs, which can be harvested and further characterized. Patients included 11 Glioblastoma, 3 Anaplastic astrocytoma, 2 Medulloblastoma, 5 Oligodendroglioma, 1 Gliosarcoma and 1 meningioma patient. Characterization of CGCs was performed using GFAP, S100 and CD45 markers. CGCs were detected in 16 out of 23 (69.6 %) patients and could be stained positively for both GFAP and S100 and negatively for CD45. Detection of viable CGCs in cases of CNS malignancies can be used for characterization of markers related to the diagnosis.

Encyclopedic tumor analysis for guiding treatment of advanced, broadly refractory cancers: results from the RESILIENT trial

RESILIENT (CTRI/2018/02/011808) was a single arm, open label, phase II/III study to test if label agnostic therapy regimens guided by Encyclopedic Tumor Analysis (ETA) can offer meaningful clinical benefit for patients with relapsed refractory metastatic (r/r-m) malignancies. Patients with advanced refractory solid organ malignancies where disease had progressed following ≥2 lines of systemic treatments were enrolled in the trial. Patients received personalized treatment recommendations based on integrational comprehensive analysis of freshly biopsied tumor tissue and blood. The primary end points were Objective Response Rate (ORR), Progression Free Survival (PFS) and Quality of Life (QoL). Objective Response (Complete Response + Partial Response) was observed in 54 of 126 patients evaluable per protocol (ORR = 42.9%; 95% CI: 34.3%–51.4%, p < 0.0001). At study completion, Disease Control (Complete Response + Partial Response + Stable Disease) was observed in 114 out of 126 patients evaluable per protocol (CBR = 90.5%; 95% CI: 83.9% - 95.0%, p < 0.00001) and Disease Progression in 12 patients. Median duration of follow-up was 138 days (range 31 to 379). Median PFS at study termination was 134 days (range 31 to 379). PFS rate at 90 days and 180 days were 93.9% and 82.5% respectively. The study demonstrated that tumors have latent vulnerabilities that can be identified via integrational multi-analyte investigations such as ETA. This approach identified viable treatment options that could yield meaningful clinical benefit in this cohort of patients with advanced refractory cancers.

Adaptive, Iterative, Long-Term Personalized Therapy Management in a Case of Stage IV Refractory NSCLC

In this paper we report long-term therapy management based on iterative de novo molecular and cellular analysis in a case of metastatic non-small cell lung cancer (NSCLC), with prior history of treated colorectal cancer. In the described case temporal tumor evolution, emergent therapy resistance and disease recurrences were addressed via the administration of personalized label- and organ-agnostic treatments based on de novo tumor profiling. This adaptive and iterative treatment strategy countered disease progression at each instance and led to the durable regression of primary as well as metastatic lesions. Concurrently, serial evaluation of mutations in cell-free circulating tumor DNA (ctDNA) via liquid biopsy (LBx) was performed to monitor disease status, ascertain treatment response, identify emergent drug resistance and detect recurrence at sub-radiological levels. The treatment management strategy described herein effectively addressed multiple, sequential clinical conundrums for which viable options were unavailable under the current Standard of Care (SoC).