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New research suggests that a modified form of MDMA — more commonly known as the illegal drug ecstasy — could kill some types of blood cancer cells. Prozac and similar antidepressants may also possess similar anti-cancer potential.

It has been known that ecstasy and other psychoactive drugs can attack cancer cells, but the problem with using a drug like MDMA to fight cancer is that the dose would have to be so large, it would kill the patient.

“That’s obviously not a very good treatment,” says John Gordon, a professor of cellular immunology at the University of Birmingham in the U.K., explaining that knowing the toxic dose gave his team a place to start when “redesigning the designer drug.”

Gordon and colleagues have developed analogues of MDMA — one that’s 100 times more powerful against lymphoma cells than MDMA and another that’s 1,000 times stronger. The experimental compounds are designed to reduce toxicity to brain cells — and possibly, therefore, the high — while increasing effectiveness against cancer cells.

The researchers say that in lab tests, the chemically engineered compounds were attracted to the fats in the cell walls of blood-cancer cells, including leukemia, lymphoma and myeloma. That made it easier for the compounds to get into cancer cells and kill them.

It was Gordon’s team that initially discovered the cancer-fighting properties of MDMA several years ago. “It started with the discovery that lymphoma cells express targets for neurotransmitters,” says Gordon.

“We made a surprising discovery that they express the serotonin transporter and later found that they express the dopamine transporter,” he says, referring to the neurotransmitters, serotonin and dopamine, that are typically found in the brain and play a role in mood and movement disorders. Both MDMA and antidepressant drugs like Prozac affect these neurotransmitters, though in different ways.

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Intriguingly, receptors for serotonin, dopamine and other neurotransmitters aren’t found just in the brain — they’re also located on immune cells. That got researchers wondering whether psychoactive drugs that affect those receptors might also affect receptors on cancer cells that grow from immune or brain cells. Gordon explains that the type of lymphoma cells being studied in his lab derive from immune cells called B-cells. B-cell cancers make up 80% to 90% of non-Hodgkins lymphoma cases.

After publishing a paper suggesting that using MDMA in a modified, less toxic dose could be a good anti-cancer strategy, Gordon was contacted by Australian researcher Mathew Piggott, who said he’d already been modifying MDMA along the same lines. Piggott is trying to develop a treatment for Parkinson’s disease — a debilitating movement disorder that involves deficiencies in dopamine — using analogues of MDMA, based on reports that some patients had found taken ecstasy and dramatically reduced their symptoms.

The two researchers decided to collaborate, with Piggott focusing on the brain effects of the drug and Gordon doing the cancer work. This month, they published their new findings on the MDMA analogues in the journal Investigational New Drugs.

It’s not clear whether the experimental compounds will produce a high like recreational ecstasy. Although full studies on their psychoactive properties have not been completed, preliminary work suggests that the analogues are less likely to do so than MDMA.

But even if the new drug does remain psychoactive, given the grueling side effects associated with most cancer treatment, having feelings of peacefulness and connection with others is unlikely to be objectionable. “You could have worse side effects,” Gordon notes wryly.

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Gordon’s research has also found that the antidepressant Prozac (fluoxetine) kills lymphoma cells in the test tube, at doses that are regularly used in the treatment of obsessive-compulsive disorder. Because the drug tends to concentrate in the brain, it may prove especially helpful against brain lymphoma, a rare and often deadly cancer that may affect people with AIDS.

The researchers were so excited about the possibility that they patented the new cancer indication and tried to get pharmaceutical companies to fund clinical trials of fluoxetine. Unfortunately, none were interested. Prozac can be obtained so cheaply, now that it’s off patent, that if even the drug were approved for the cancer indication, it wouldn’t be profitable.

“My plea is to at least have a look if everything else has failed in brain lymphoma. I can’t see any harm in trying Prozac, at least as adjunct [to other treatment]. That to me would be the obvious first question to ask, and if you were to see some efficacy there for brain lymphoma, then go to the next step and [fund trials] for other lymphomas,” says Gordon.

Maia Szalavitz is a health writer for TIME.com. Find her on Twitter at @maiasz. You can also continue the discussion on TIME Healthland‘s Facebook page and on Twitter at @TIMEHealthland.