Startups seek perfect particles to search and destroy cancer

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April 18, 2003 — Cancer, one of mankind’s oldest threats, is about to come under attack from one of its newest tools: nanoparticles.

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Building on a body of established medical research, several companies are pushing forward new cancer treatments that send nanoparticles into patients to find tumor cells. Once they do, doctors excite the particles with electromagnetic energy to attack the tumor — essentially, heating them up so much that they cook the cancer to death.

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“Nano hype in general is terrible,” said John Zhang, head of a 10-person research team at Georgia Tech that is testing nanoparticle effectiveness against a variety of tumors. “But nano here can do things nothing else can do.”


Two startup companies pursuing nanoparticle treatments are Triton BioSystems Inc. in Chelmsford, Mass., and Nanospectra Biosciences Inc. in Houston. Both are still conducting animal trials and say human treatments won’t be available for another two years at the earliest.


Triton BioSystems’ approach is to bond iron nanoparticles and monoclonal antibodies into bioprobes about 40 nanometers long. The probes are injected into the body, where the antibodies sniff out tumor cells and bind to their membranes. Once the tumor is covered with bioprobes, a magnetic field generated from a portable alternating magnetic field machine (akin to a souped-up miniature MRI machine) heats the iron particles to more than 170 degrees. The cells die almost immediately.


Nanospectra Biosciences’ approach is to inject spherical “nanoshells” of gold and silica into the patient. The shells circulate through the body until they naturally pile up near tumor cells. Then doctors use an infrared laser to heat the shells and kill the tumor tissue. Unlike Triton Biosystems, Nanospectra specifically targets micrometastases, the tiny enclaves of cancer cells too small for surgeons to find and remove with a scalpel. (Triton BioSystems targets both visible tumors and micrometastases.)


In both cases, the technologies seem to kill tumor cells without any accidental damage to nearby healthy cells. And from the data observed so far, test subjects seem to feel no pain from the heat generated. Once the cells are destroyed, the body’s excretion system kicks in and removes cellular residue and nanoparticles alike.


The goal in all this research is to achieve the same results as chemotherapy and radiation, the traditional methods of fighting cancer, without their frightening side effects: hair loss, nausea, ravaged immune systems. The nanoparticles themselves are chemically inert; their sole function is to find tumor cells and stay put.


“There is a tremendous amount of literature saying we can get the particle to the tumor,” said Donald Payne, Nanospectra’s chief executive. “The problem was that they were trying to deliver a container of drugs. Those are issues we don’t have to face.”


Samuel Straface, chief executive at Triton BioSystems, likened chemotherapy to napalm: It works by killing large swaths of tissue in hopes that all tumor cells are killed in the process. Nanoparticles function more like carefully planted explosives detonated by remote control.


“Chemotherapy is nasty stuff,” he said. “The effects here are minimal. We expect virtually no collateral damage.”


Exactly how nanoparticle therapy would work in humans is unclear. Straface believes his bioprobes would generally need several hours to reach tumors and a few seconds to eradicate them. Payne said that after allowing several hours for the nanoshells to collect near the tumor, excitation and tumor death would take seconds. Also unclear is whether doctors would attack tumors in specific areas or simply expose a patient to one full-body dose of treatment.


Other business and academic researchers are also pursuing the nanoparticle potential. Crystalplex Corp., based in Pittsburgh, is trying to use nanoparticles to detect cancer rather than treat it. At Georgia Tech, scientists are also exploring approaches similar to Triton BioSystems’ and Nanospectra’s.


Zhang said that scientists have suspected for years that nanoparticles would be useful tools against cancer but didn’t know how to make the right type of particle. Often the particles were so small they could not be excited by energy fields; those that were large enough (several millimeters) were too big to navigate the body or were attacked by antibodies.


Triton BioSystems began working on mouse trials in 2002. Tests so far have shown that the treatment itself brings no ill effects to the mice, and Straface is now nearly finished with efficacy trials to see how the treatment actually works on tumors. Once those trials are done, the company will start designing human tests and ask the FDA for permission to begin in 2004.


The company received seed funding from Millennium Materials Technology Fund, an investment group based in Israel. Straface expects to raise another $2 million soon from angel investors. He has not solicited venture capital firms. And while Triton BioSystems shares office space with Triton Systems, a much older and larger nanomaterials company, the two businesses are separate entities.

Nanospectra is still at least 18 months away from human trials. At best, therapies won’t find their way into oncologists’ offices until 2006. The company has three full-time employees, and leans on the University of Texas MD Anderson Cancer Center and Rice University for consulting and clinical support. Both institutions have contributed funding to the startup. Payne said the company also has cash from angel investors. He did not specify how much but described it as “not a huge amount.”


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