Medsaic sets out to profile leukaemia

A Sydney company is hoping pathologists will be making room next to their flow cytometers for a new technology which provides doctors with a detailed profile of leukaemias and lymphomas, setting the scene for tailored treatment.

Medsaic -- a University of Sydney spin-off -- is also aiming to use its microarray 'Dotscan' technology to work at the forefront of personalised medicine, using the disease profile results to determine the "right medicine for the right person at the right dose", even before a pill has passed a patient's lips, according to company chairman Eric Tan.

Dotscan is a microscope slide on which 82 different antibody dots are printed, specific for 82 leukaemia cell surface antigens. White blood cells from a patient suspected to have leukaemia are dropped onto the array and incubated. Different types of leukaemia exhibit different assortments of characteristic surface antigens. If a cell expresses a particular antigen, it will latch on to the corresponding antibody, which is anchored on a dot on the slide.

The Medsaic scanner then quantifies the intensity of the dots and converts them into a digital image. The resulting dot pattern can be analysed and compared to that of known leukaemia types.

The company has been testing the kit for about a year at a number of sites, including Mayne Health, Westmead, the Royal Melbourne Hospital and the MD Anderson Cancer Centre in Texas.

Currently, pathologists pick up clues to whether a patient has leukaemia by looking at cell morphology, flow cytometry, cytochemistry and karyotype analysis.

Flow cytometers -- the pathologist's main tool in diagnosis of leukaemia and many other conditions -- use fluorescently labelled probes (often antibodies) and laser technology to detect cell surface antigens. But they have drawbacks, requiring expensive reagents, highly experienced staff, and a relatively large amount of antibody. They also generally detect only 10 to 20 different cell surface antigens.

Prof Ken Bradstock, head of Blood & Marrow Transplant Services at Westmead Hospital, confessed that at first he was sceptical, but finally he had been won over by the Medsaic microarray. He said the technology represented the third big advance in diagnostics, following molecular biologist Cesar Milstein's development of monoclonal antibodies in the 1980s and the development of the flow cytometer in Silicon Valley in the 1990s.

Tan explained that as the DotScan slide can be printed with 320 antibodies, the company also hopes to develop microarrays to "screen a whole lot of potentially efficacious antibodies by observing the degree of binding."

"If we can demonstrate that this there is binding between the antibody and the cell, then there is evidence that the antibody is likely to work in the in vivo situation," he said.

The potential advantage of this type of 'personalised medicine' will be to determine whether a patient is likely to respond to treatment -- particularly monoclonal antibody therapeutics.

Diagnosis, not monitoring

Stephen Mulligan of Mayne Health -- one of the pilot sites for DotScan -- said that different malignancies exhibit different antigen profiles. He said there was a high level of correlation between the current flow cytometry diagnostic used by pathologists and Medsaic's dot array technology. But he warned that the Medsaic microarray was not a way of looking at minimal residual disease, where there is only a small population of abnormal white blood cells.

"If you've got a clear leukaemic population, you will get a clear results from your microarray," he said, noting that the microarray will be best used for diagnosis, not monitoring.

"In the near future, for a clear leukaemic population, it won't be long before you're not doing flow cytometry," he predicted.

He said that the most important aspect of the array would be its ability to shape the direction in which therapeutic antibodies are designed.

"It will not do everything," said Medsaic CEO Jeremy Chrisp. "But it is cost-effective for rapid immuno-phenotyping of leukaemias."

Chrisp expects Dotscan to be available this month. Tan hopes the company will sell 4000 units in the first year.

DotScan has been assigned a Medicare rebate item number, and Medsaic has appointed the Australian arm of international laboratory instruments company Beckman Coulter to distribute the technology. International regulatory approval and sales are also planned.

Medsaic also intends to extend its range of products to cover three market segments -- haematological malignancies, solid tissue tumours and autoimmune diseases.

Medsaic's money trail

Having filed a provisional patent in 1998, Medsaic received seed funding from the University of Sydney and later commonwealth government COMET and BIF grants. Support was also provided by the BioFirst and BioBusiness programs of the NSW Department of State and Regional Development.

Its major investor -- with a 40 per cent equity stake -- is now Perth biomedical venture capital company, Symbion, which was founded by surgeon Eric Tan three years ago.

Symbion has raised $5.5 million from private investors and ABN AMRO. Listed healthcare investor Medical Corporation Australasia (ASX:MOD) also took a 20 per cent holding in the company.

Tan has set himself the brief of investing in spin-off companies in the eastern states, anchoring Medsaic with a $3 million investment and putting $1 million into University of Technology, Sydney spin-off PacMab, which he said was due to list "after Easter".

"Because I'm a doctor I can very quickly have a feel for how useful a particular technology is to deliver a health benefit," he said.

His previous commercial experience has been in establishing a private hospital in Hanoi, and in a Chinese health products company, Hangzhou Pollen Pharmaceutical.