Therapy-boosting nanoparticles enter trials

[Agloco]

While most folks here are interested in mostly "sexy" physics, I thought I'd post about some of the new developments at the crossroads of physics and medicine periodically. Here's a neat one.

http://medicalphysicsweb.org/cws/article/research/47180


Increasing local control of cancer remains a key challenge for improving patient outcome, with radiotherapy limited by the need to balance therapeutic and adverse effects. High-density nanoparticles are under investigation as a means to enhance the local efficacy of radiotherapy without increasing damage to surrounding healthy tissue.

It's being considered as a form of boost therapy. This little contraption uses activated Hafnium after direct intratumoral injection to effect tumor control. We use photons (in the range of 6MV) to iradiate the particles after verifying they're in place. Irradiation of Hafnium causes excitation of electrons which then deposit their energy into the surrounding medium (the tumor).

A lot of dosimetric/tumor control studies still remain to be done. Also, one must consider that accurate and reproducible tumor localization is tricky in many cancers (prostate for instance). This makes image guided intratumoral injection of these particles the next great challenge to overcome.

[MannyIsGod]

You basically inject the tumor with foil and then stick it in a microwave?

[Agloco]

You basically inject the tumor with foil and then stick it in a microwave?

:lol

If Republicans get thier way with healthcare you and I are heading down to the patent office.

[boutons_deux]

Kanzius' similar approach of using harmless RF to agitate molecules that attached themselves to cancer cells is safer than any ionizing radiation, which often causes secondary cancers. The RF-heated molecules' kills the cancer cells, that die at as low as 105F. As nasty as cancer is, warm-to-touch 115F heat kill it while not bothering healthy cells.

http://www.kanziuscancerresearch.org/index.php

Hyperthermia is one of the cancer treatments in Germany that isn't used in USA. The big problem is that there's not enough money in hyperthermia for US' disease profiteers to pursue it.

[Agloco]

Kanzius' similar approach of using harmless RF to agitate molecules that attached themselves to cancer cells is safer than any ionizing radiation, which often causes secondary cancers. The RF-heated molecules' kills the cancer cells, that die at as low as 105F. As nasty as cancer is, warm-to-touch 115F heat kill it while not bothering healthy cells.

http://www.kanziuscancerresearch.org/index.php

Hyperthermia is one of the cancer treatments in Germany that isn't used in USA. The big problem is that there's not enough money in hyperthermia for US' disease profiteers to pursue it.

That's part of it B, but you're a bit off the mark on this one. There's another confounding variable at play.

Yes, this is an area of big research. Initially, high frequency ultrasound was used to either heat tissue directly or heat gold nanoparticles which were targeted to the site. Here is where the uncertainty lies:

1) Dosimetry (if we can call it that for RF) on tumor control probability (TCP) via coagulative necrosis is poorly characterized as of today. In English, it means that there isn't enough long term (10-15 year follow up) data to justify a headlong rush into the technology. This is in stark contrast to ionizing modalitites.

2) Nanoparticles work on a principle called enhanced permeability and retention (EPR). Basically, tumor vasculature is known to be "leakier" than normal vasculature (for reasons I won't go into here). What you amost never see in these sorts of studies is a good characterization of how many of the nanoparticles actually stay in the tumor over time. They don't all magically find the leaky vessels and lymphatics will eventually drain them out, albeit at a much slower rate than normal (has to do with incread hydrostatic pressures within the tumor). Understand that if you ever do see a well characterized uptake and retention study, it invariably utilizes animal models. Usually rats or mice whch have been immunocompromised to allow rapid growth of human cell lines. How well does that data translate to a human where the host immune response is intact and tumors necessarily develop advanced resistances and defense mechanisms? Here I don't mean against heat per se, but to the agents which are supposed to imbed in the tumor to allow delivery of.

So what does that mean? Well, it means that molecular targeting (and hence any therapeutic modality derived thereupon) is still in its infancy. Also, as this is a clinical matter, those pesky long term outcome studies matter. Is this safer than ionizing modalities? Absolutely in terms of secondary cancer induction risk. The big question is how safe is it in terms of primary cancer eradication? Here we need long term follow up studies and accurate TCP modeling for non-ionizing modalities, things which simply don't exist in suficient quantity yet. Those are other reasons why it's not practiced in the US. These things are a strong function of human protection laws (another thread).

I'd say with certainty though B that the article you presented will represent the eventual direction we should, and will go in with this research.

[boutons_deux]

"In English, it means that there isn't enough long term (10-15 year follow up) data to justify a headlong rush into the technology. This is in stark contrast to ionizing modalitites."

there are NO long term results for any new treatment, so that means we don't try?

there's plenty of long-term results for radiation, and that includes outright success, or success with the primary cancer only to cause long-term secondary cancers from radiation damage, which is why radiation is not preferred for younger patients. The longer you live after radiation, the more chance you give secondary cancers to develop.

there's plenty of long term results for chemo, and that says it's a failed treatment but a fantastic business. It's especially horrible for pediatric cancers, since kids who survive cancer and chemo have long-term diseases and organ failure throughout their lives.

[Agloco]

"In English, it means that there isn't enough long term (10-15 year follow up) data to justify a headlong rush into the technology. This is in stark contrast to ionizing modalitites."

there are NO long term results for any new treatment, so that means we don't try?

lol....no B, it means that we don't offer it outside of an "experimental" designation. That's what Clinical Phase Trials are for.