HighlightsAlveolar Echinococcosis is a rare but potentially fatal parasitic infection primarily affecting liver.The diagnosis and treatment can be difficult and clinical misinterpretation as malignancy is not rare.The principal treatment of Alveolar Echinococcosis is surgery accompanied with chemotherapy.

BACKGROUNDOne of the most notable applications for circulating tumor DNA (ctDNA) detection in peripheral blood of patients with metastatic colorectal cancer (mCRC) is a long-term postoperative follow-up. Sometimes referred to as a “liquid (re)biopsy” it is a minimally invasive procedure and can be performed repeatedly at relatively short intervals (months or even weeks). The presence of the disease and the actual extent of the tumor burden (tumor mass) within the patient’s body can be monitored. This is of particular importance, especially when evaluating radicality of surgical treatment as well as for early detection of disease progression or recurrence.AIMTo confirm the radicality of surgery using ctDNA and compare available methods for detection of recurrence in metastatic colorectal cancer.METHODSA total of 47 patients with detected ctDNA and indications for resection of mCRC were enrolled in the multicenter study involving three surgical centers. Standard postoperative follow-ups using imaging techniques and the determination of tumor markers were supplemented by ctDNA sampling. In addition to the baseline ctDNA testing prior to surgery, a postoperative observation was conducted by evaluating ctDNA presence up to a week after surgery and subsequently at approximately three-month intervals. The presence of ctDNA was correlated with radicality of surgical treatment and the actual clinical status of the patient.RESULTSAmong the monitored patients, the R0 (curative) resection correlated with postoperative ctDNA negativity in 26 out of 28 cases of surgical procedures (26/28, 93%). In the remaining cases of R0 surgeries that displayed ctDNA, both patients were diagnosed with a recurrence of the disease after 6 months. In 7 patients who underwent an R1 resection, 4 ctDNA positivities (4/7, 57%) were detected after surgery and associated with the confirmation of early disease recurrence (after 3 to 7 months). All 15 patients (15/15, 100%) undergoing R2 resection remained constantly ctDNA positive during the entire follow-up period. In 22 cases of recurrence, ctDNA positivity was detected 22 times (22/22, 100%) compared to 16 positives (16/22, 73%) by imaging methods and 15 cases (15/22, 68%) of elevated tumor markers.CONCLUSIONctDNA detection in patients with mCRC is a viable tool for early detection of disease recurrence as well as for confirmation of the radicality of surgical treatment.

Background: Detection of circulation tumor DNA (ctDNA) in plasma has become a viable option for non-invasive monitoring of patients. Also termed “liquid biopsy” the approach is applicable for pre-diction of response and prediction of resistance to biological therapy (1, 2). Various techniques have been used for ctDNA detection, frequently employing clonal amplification on a digital PCR format (3) with limits of detection (LOD) below 0.01% of mutant alleles. However, these techniques suffer from high complexity, expensive instrumentation, and a considerable cost per sample. We hereby present a simple low-cost alternative that is implementable to routine ctDNA testing. Methods: A panel of PCR amplicons (106 - 174bp) was resolved by denaturing capillary electrophoresis (DCE) revealing minute presence of mutation specific hetero-duplexes. The final panel consisted of clinically relevant oncogenic mutations KRAS, NRAS, BRAF, PIK3CA and EGFR as well as cancer-related mutations in tumor suppressors TP53, APC and CTNNB1. A total of 299 patients was subsequently examined for presence of ctDNA in plasma including 194 with colorectal cancer (CRC), 26 with NSCLC and 79 with pancreatic cancer (PanC). CtDNA status was correlated to TNM stage and tumor markers (CEA and Ca19-9). In a subset of CRC patients (n = 20) the ctDNA was monitored in 2 - 6 month intervals and correlated to the therapy response. Results: The experimental LOD value was in the range between 0.03 - 1% for all tested mutations within the panel. A minimum input amount of DNA was 5 pg (0,005 ng).. The overall rate of ctDNA detection was 32% for CRC (stages I - IV), 31% for NSCLC (stages III - IV) and 27% for PanC (stages II - IV). The highest detection rate, 69%, was observed in Stage IV CRC patients. Comparison with tumor markers (TM) revealed 62% of cases positive for both TM and ctDNA and 13% TM-negative cases with ctDNA positivity. Post-operative absence or persistence of ctDNA was related to the radicality of the surgical treatment and the ctDNA levels were concordant with the response to adjuvant chemotherapy. In several patients a disease progression was signalized based on ctDNA even prior to actual clinical detection by CT imaging. Conclusion: DCE is a simple technique applicable for detection of ctDNA in cancer patients without a need for costly hardware/software equipment. The detection rates are 10 - 15% lower compared to the dedicated dPCR techniques, however, the method requires ca 100x less input DNA, the cost per patient is about 10-fold lower and the turnaround time per test is under 5 hours. Supported by the Czech Ministry of Health Grant 14383. Literature 1. Bettegowda C et al. Sci Transl Med. 2014,6(224):224ra24 2. Douillard JY et al. J Thorac Oncol. 2014, 9(9):1345-1353. 3. Benesova L et al. Anal Biochem 2013,433(2):227-234. Citation Format: Lucie Benesova, Barbora Belsanova, Petra Minarikova, Tereza Halkova, Jiri Pudil, Filip Pazdirek, Milos Pesek, Ondrej Fiala, Jiri Hoch, Miroslav Zavoral, Bohus Bunganic, Miroslav Levy, Ludmila Lipska, Lubos Petruzelka, Miroslav Ryska, Marek Minarik. Validation of a simple low-cost method to monitor ctDNA in patients with solid cancers. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2406. doi:10.1158/1538-7445.AM2015-2406