Media Releases

Understanding Circulating Tumour Cells

November 21, 2016

U of T’s Kelley Group develops new tool to track traveling cancer cells

Toron­to, ON – Can­cer­ous tumours are known to release cells into the blood­stream, and it is these cir­cu­lat­ing tumour cells or CTCs that are the sources of metasta­t­ic tumours – tumours that spread and form in dis­tant loca­tions in the body.  In fact, most patients who suc­cumb to can­cer do not die because of the ini­tial tumours that form, but rather because of the dead­ly sec­ondary metasta­t­ic tumours that appear at dis­tant sites.  As a result, under­stand­ing the biol­o­gy and clin­i­cal rel­e­vance of these trav­el­ing cells is crit­i­cal in our fight against can­cer.

Mon­i­tor­ing cir­cu­lat­ing tumour cells, how­ev­er, is a tremen­dous chal­lenge as they are out­num­bered in blood by healthy cells at a lev­el of over 1 bil­lion-to‑1.  More­over, they can dis­play var­ied and dynam­ic prop­er­ties, and the col­lec­tion of CTCs found in the blood­stream of a can­cer patient may have dif­fer­ing metasta­t­ic poten­tial.  Con­se­quent­ly, efforts to inte­grate the analy­sis of these cells into main­stream clin­i­cal med­i­cine have been lim­it­ed because it has been dif­fi­cult to pin­point what types of cells and what phe­no­typ­ic prop­er­ties should be tar­get­ed.  But the poten­tial of CTCs to allow the col­lec­tion of a non-inva­sive “liq­uid biop­sy” to mon­i­tor can­cer pro­gres­sion is a tan­ta­liz­ing pos­si­bil­i­ty that has con­tin­ued to attract sig­nif­i­cant atten­tion to this prob­lem.

A break­through by Pro­fes­sor Shana Kelley’s research group at the Uni­ver­si­ty of Toron­to pub­lished in Nature Nan­otech­nol­o­gy pro­vides a new tool to char­ac­ter­ize CTCs that may help can­cer biol­o­gists and clin­i­cians under­stand how to use these cells to pro­vide bet­ter treat­ment.  Using mag­net­ic nanopar­ti­cles, CTCs in blood sam­ples were tar­get­ed based on pro­teins dis­played on the cell sur­face, and sep­a­rat­ed based on the lev­els of the pro­tein present.  Using a high–resolution microflu­idic device, cells are then sep­a­rat­ed into 100 dif­fer­ent cap­ture zones to gen­er­ate a pro­file that pro­vides phe­no­typ­ic infor­ma­tion relat­ed to metasta­t­ic poten­tial.  Using this approach and mon­i­tor­ing cells gen­er­at­ed in ani­mal mod­els of can­cer and in sam­ples col­lect­ed from prostate can­cer patients, the prop­er­ties of CTCs were shown to evolve and become more aggres­sive as tumours became more advanced.

“Through this approach, we aimed to pro­vide a new way to pro­file CTCs beyond sim­ply count­ing their num­bers in clin­i­cal sam­ples,” explained Dr. Mahla Poudineh, lead stu­dent author on the paper.  “Instead, we want­ed to pro­vide phen­to­typ­ic infor­ma­tion that might allow these cells to be clas­si­fied as benign or more dan­ger­ous, which would then inform treat­ment options.”

“We were very for­tu­nate to col­lab­o­rate with a num­ber of oncol­o­gists at the Sun­ny­brook Research Cen­tre and Princess Mar­garet Hos­pi­tal as we devel­oped this tech­nol­o­gy so that we could test our approach with real patient spec­i­mens and bet­ter under­stand how to adapt it for use in the clin­ic,” not­ed Dr. Kel­ley.

The Kel­ley group (, along with col­lab­o­ra­tors in the Sar­gent group ( at the Uni­ver­si­ty of Toron­to, hope to turn the approach they report­ed into a device that can be used by can­cer researchers and even­tu­al­ly clin­i­cians to allow CTC analy­sis to be mon­i­tored rou­tine­ly and used to lim­it the pro­gres­sion of can­cer.

Read the paper, “Track­ing the dynam­ics of cir­cu­lat­ing tumour cell phe­no­types using nanopar­ti­cle-medi­at­ed mag­net­ic rank­ing,” at Nature Nan­otech­nol­o­gy:

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For more infor­ma­tion about this break­through dis­cov­ery, please con­tact:

Jef Ekins
Man­ag­er, Mar­ket­ing & Com­mu­ni­ca­tions
Leslie Dan Fac­ul­ty of Phar­ma­cy, Uni­ver­si­ty of Toron­to

Shana Kel­ley
Leslie Dan Fac­ul­ty of Phar­ma­cy, Uni­ver­si­ty of Toron­to