Implanting batteries to fight tumors

The Problem

Cancer is bad. I don’t think we need much more of an intro to understand why new strategies to fight cancer are needed.

For decades, we’ve used surgery+chemo+radiation for treatment. Recently, immunotherapies and cell therapies have beefed up our arsenal some, but not for most patients.

My main point is that we need new treatments. And some of the new treatments should be things completely different from what we’ve tried before, not just another new chemo combination.

Something people probably haven’t tried, you say?

How about putting batteries into tumors?

You read that correctly. Taking a battery and just sticking it into a tumor.

Batteries killing tumors. I know I’m being repetitive but it’s just such an insane idea that it took me repeating it to myself a few times for it to stick.

The Solution

Well, that’s what this week’s authors did. And it worked beautifully, shockingly well.

They designed a small, implantable battery that turns oxygen into a toxic molecule called reactive oxygen species (ROS). ROS are toxic to cells (including tumor cells).

Getting rid of oxygen and replacing it with toxic ROS molecules → tumor death.

The batteries use oxygen as part of their charging process and then discharge the toxic ROS molecules as they discharge.

The authors put their tumor-killing battery into a liquid representing the tumor environment and measured how well the battery worked. It quickly consumed the oxygen in the liquid.

The liquid had a dye that turns red/pink as the oxygen is depleted. As you can see below, the batteries quickly used all the oxygen in the liquid.

To test out the system, the authors grew breast cancer cells in a petri dish and put a battery in with them. As intended, the battery consumed all the oxygen and killed most of the cancer cells.

The next step was to see if the batteries helped treat cancer in mice and to combine them with complementary drugs.

Some promising cancer drugs need there to be low amounts of oxygen to become active.

However, these drugs have done poorly in clinical trials. While tumors have lower amounts of oxygen than healthy tissue, they’re inconsistent and not low enough to activate most of these drugs. They work a little bit but not that well.

As we know, the battery should use up all the oxygen in the tumor. This makes low oxygen-activated drugs a perfect complement to the batteries.

When combined, the battery and low oxygen-activated drug treatment eradicate tumors in mice (DB+TPZ in the graph below).

The graph above shows the tumor volume over time. The batteries by themselves (DB) reduced the tumor growth by a lot.

Tumor growth was stopped completely when the batteries were combined with the low oxygen activate drug (DB+TPZ). However, the low oxygen drug TPZ was ineffective by itself, showing that it needed the batteries to become activated.

This is one of the craziest papers I’ve read in a while.

I love it.

Combining what seems like two completely separate fields into one project requires huge amounts of creativity. It’s not as simple as “oh batteries use oxygen, tumor cells need oxygen, let’s use the battery to kill tumors”.

I know some batteries use oxygen. I know tumors need oxygen. I would have never thought to do this. In my mind, batteries and cancer biology fit into two distinct boxes. They don’t overlap.

The ability to take information from one box and match it with info from another box takes extreme mental flexibility.

A lot of impactful science is done by combining two simple but unrelated concepts into something brand new.

See you next week for more science,

Neil

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