Diagnostics · Rare cell detection
X-ZELL
A Singapore and Bangkok company that set out to find early cancer in a 10mL blood draw, published one 146 patient prostate study, then turned the staining machine built for that test into the product it sells today. The blood test is no longer on its website.
One cell in five billion
Asked in 2020 to describe his company in one tweet, Sebastian Bhakdi wrote that X-ZELL had found “an accurate, affordable and globally scalable way of detecting early-stage cancers in small, 10mL blood samples.” He ended it with a hashtag: #nottheranos.
The biology behind the pitch was real. A tumour grows its own blood vessels, and those vessels shed endothelial cells into the circulation. Those cells, tumour-associated circulating endothelial cells or tCEC, look almost exactly like healthy blood cells, which is why they had long been treated as “undetectable in clinical routine.” X-ZELL said it could pull “a single tCEC among five billion healthy blood cells” and put it on a glass slide a pathologist could read. In practice that meant freezing cells straight onto a slide instead of soaking them in formalin, then staining eight or nine antibody colours at once rather than one at a time.
The gap it aimed at
Prostate specific antigen testing has a known dead zone. Between roughly 4 and 10 ng/mL a reading says almost nothing useful, and guidelines still send the man to biopsy. The 2019 X-ZELL paper put the cost plainly: over 80% of biopsies are performed on healthy men or on men with cancer that would never have harmed them. A cheap test sitting between PSA and the biopsy needle, ruling men out rather than in, would be worth a great deal.
From malaria to cancer
Bhakdi trained as a physician at Freiburg, then took a postgraduate degree in international health at the Autonomous University of Barcelona. A German Research Foundation fellowship on malaria took him to Mahidol University in Bangkok, where he built a magnetic method for pulling infected red cells out of small blood samples. He applied the same separation to cancer patients and saw cells nobody expected. X-ZELL grew out of that patent, was established in Bangkok, and moved its head office to Singapore in 2019.
The one study
Between July 2016 and October 2017, 170 men at Siriraj Hospital in Bangkok gave 10mL of blood immediately before a transrectal ultrasound guided biopsy. Twenty four were dropped: three inconclusive biopsies, three clotted samples, eighteen technical failures in the tCEC analysis itself. That left 146.
In the grey zone below 10 ng/mL, the test read 75% sensitive and 67% specific for clinically significant cancer, with a negative predictive value of 93%. Adding it to PSA lifted positive predictive value from 17% to 32%. The authors called it “the first level-2 evidence for this biomarker in prostate cancer” and were candid about the reference standard: “TRUS biopsy is not an ideal reference test.”
The company compressed that into a marketing line: the study showed it could have avoided 7 in 10 unnecessary biopsies “without missing any clinically significant cases.” The paper says otherwise. Three of the 41 men with a negative tCEC result had clinically significant cancer on biopsy, one of them Gleason 4 + 4 with stage T3a disease. The test missed them.
The trial that went quiet
In November 2020 X-ZELL announced a blinded 400 patient validation study at National University Hospital and Singapore General Hospital, run through A*STAR’s Diagnostics Development Hub. Bhakdi said tCEC testing might reach Singaporean patients as early as 2023. Searches of ClinicalTrials.gov return no registration under the company, the founder or the biomarker, and no result has been published. What that study found, if it finished, is not on the public record.
Selling the shovel
Meanwhile the instrument built to make the blood test possible found buyers of its own. German and Slovenian cytology laboratories began using the staining suite on pleural fluid and fine needle aspirates, where the constraint is that every stain consumes part of a tiny sample. By March 2026 X-ZELL was selling pre-configured seven antibody panels; in April 2026 those panels got a CE mark under the EU in vitro diagnostic regulation. The website today sells instruments, panels, antibodies and reagents to laboratories. It carries no blood test, no prostate product and no screening claim, and it states its own limit: “Clinical performance must be established in the intended patient-specimen context.”
What is proven, and what is still claimed
| Evidence | What the record shows | Source type |
|---|---|---|
| Prostate study | Bhakdi et al., Cancers, July 2019. Prospective, blinded, single centre, Siriraj Hospital Bangkok. 170 enrolled, 146 analysed. PSA under 10 ng/mL: sensitivity 75% (95% CI 43 to 95), specificity 67% (53 to 79), PPV 32% (16 to 52), NPV 93% (80 to 98), versus PSA alone at 17% PPV, p = 0.0012. | Public record |
| Study funding and interests | The paper states “Financial and material support was provided by X-ZELL Singapore” covering design, conduct, analysis and manuscript. The first author is the founder and CEO. It also states: “The authors declare no conflict of interest.” | Public record |
| Company summary of that study | Company materials say the test would have avoided more than 70% of unnecessary biopsies “without missing any clinically significant cases” on 174 patients. The paper analysed 146, and three men with a negative test had clinically significant cancer. | Differs from the paper |
| Registered trials | No study sponsored by X-ZELL, Bhakdi or naming tCEC appears on ClinicalTrials.gov as of Sep 2026. The announced 400 patient Singapore study has no registration and no published result. | Not found |
| US regulatory status | No 510(k), no PMA and no entry in FDA device registration and listing data. The company said in March 2024 that two instruments “have now been listed with the United States Food and Drug Administration (FDA)”. Listing is an administrative step, not a clearance. | Public record |
| EU regulatory status | Three effusion cytology panels CE marked under IVDR, announced April 30, 2026, after research use only sale from March 2026. Instruments described as CE marked under IVDR and MDR and EUDAMED listed since 2024. | Company-stated |
| Independent cytology evidence | Miceska, Kholová and Kloboves Prevodnik, Acta Cytologica, 2026, Institute of Oncology Ljubljana. Described by the authors as preliminary results on fine needle aspirates and effusions, with immunocytochemistry as the reference. | Independent |
| German routine laboratory data | A blinded 213 patient comparison with cell block immunohistochemistry presented by PD Dr Achim Battmann at the 2024 European Congress of Cytology, reported as raising true positive diagnoses from 11.7% to 19.2%. No peer reviewed publication of the final data found. | Conference, company-reported |
Read plainly: X-ZELL has one peer reviewed diagnostic accuracy study, in one cancer, at one hospital, in a high risk population already headed for biopsy. That is level 2 evidence by the authors’ own grading, and it is a triage result, not a screening result. No regulator has authorized a cancer screening test from this company. What it does have regulatory standing for is narrower: antibody panels and staining instruments that help a cytopathologist get more out of a small sample.
What to watch
- Any result from the 400 patient Singapore study announced in November 2020.
- Whether the tCEC work is published again. The last prostate paper is from 2019.
- The Ljubljana and Frankfurt cytology data in a journal rather than a conference slide.
- Whether X-ZELL raises again. The last announced financing closed in October 2020.
- Category context: Grail reported PATHFINDER 2 results in October 2025 from more than 23,000 people, at 40.4% episode sensitivity and 99.6% specificity, and is still working toward an FDA premarket approval decision.
In their words
“By fusing next generation cell detection technology with cutting-edge #AI, @XZELLInc has found an accurate, affordable and globally scalable way of detecting early-stage cancers in small, 10mL blood samples. We call it single-cell pathology. #nottheranos”
Sebastian Bhakdi, founder and CEO, PetaCrunch interview, June 2020 · Interview
“The study demonstrated that X-ZELL would have been able to avoid 7 in 10 unnecessary prostate biopsies in these so-called grey-zone patients without putting any of them at risk.”
Sebastian Bhakdi, PetaCrunch interview, June 2020 · Interview
“The clinical challenge in prostate cancer diagnostics is to distinguish men with low-risk cancer that does not require intervention, from those who need medical attention.”
Dr Sidney Yee, CEO, A*STAR Diagnostics Development Hub, quoted in the November 2020 release · Company release
“X-ZELL can provide actionable diagnostic information on the same day, compared to up to 48h using the conventional IHC method”
PD Dr Achim Battmann, chief pathologist, MVZ Frankfurt, October 2023 · Company release
“A major advantage of the workflow is the standardised fixation and staining process, which delivers reproducible results and allows up to seven times more markers per slide.”
Prof Dr Veronika Kloboves-Prevodnik, Institute of Oncology Ljubljana, October 2025 · Clinician
“To our knowledge, these are the first IVDR CE-marked multiplex antibody panels specifically designed for cytology.”
Sebastian Bhakdi, CE mark release, April 2026 · Company release
Related companies
Sources
- Public recordAccuracy of Tumour-Associated Circulating Endothelial Cells as a Screening Biomarker for Clinically Significant Prostate Cancer
- Public recordClinicalTrials.gov queries for X-ZELL, Bhakdi and tCEC: no matching study
- Public recordFDA 510(k), PMA and registration and listing queries: no matching record
- Public recordUS patent application 20190094115, applicant X-Zell Inc.
- Public recordSEC EDGAR Form D search for X-ZELL: no filing found
- IndependentESMO: Grail eyes FDA review with boosted Galleri data
- InterviewX-ZELL, a scalable way of detecting early-stage cancers
- IndependentThis Startup Is Changing Cancer Detection Around the World
- CompanyX-ZELL website: home, about, technology, publications
- CompanyY Combinator company profile for X-Zell
- CompanyX-ZELL closes oversubscribed Seed+ round
- CompanyX-ZELL technology now US FDA-listed and IVDR-compliant
- CompanyEarly adopters share first-hand experience with Cryoimmunostaining technology
- CompanyX-ZELL Cryophore Panels achieve IVDR CE Mark
Profile researched and written by Healthcare Discovery. Last updated September 29, 2026.
