Is a newly announced cancer therapy touted as "unprecedented" as game-changing as it's said to be? It's simply too soon to tell. At the annual meeting of the American Association for the Advancement of Science on Sunday, Stanley Riddell, an immunotherapy researcher and oncologist at Seattle's Fred Hutchinson Cancer Research Center, announced an exciting potential treatment.

"The early data is unprecedented," Riddell said during Sunday's media conference in D.C.

Riddell and his colleagues are working on immunotherapy. While chemotherapies attack tumors and cancer cells directly — usually causing significant damage to healthy tissues in the process — immunotherapy is about finding ways to help the human immune system fight off cancer cells the way it would attack foreign bacteria or a virus. Cancer cells are adept at outlasting or hiding from immune responses, so immunologists have to find ways to trigger the immune system to act out anyway.

Jill O'Donnell-Tormey, chief executive of the Cancer Research Institute, said 2015 was "a truly special year for cancer immunotherapy" — and more than half of active clinical cancer trials use some form of it. With the White House set to fund a cancer "moonshot" to the tune of $1 billion, many are looking to immunotherapy as the best hope for a cure — or at least a much better treatment — for cancer.

According to Riddell, his team's studies on a technique called adoptive T cell therapy are seeing stupendous results. In this process, doctors take white blood cells called T cells from cancer patients and genetically modify them, giving them tags that will help them to target specific cancer cells in the body. The doctors then allow these cells to multiply and reintroduce them into the body, providing patients with a super-charged immune system tailored to fight the cancerous cells inside of them. In theory, these cells could keep protecting the body from cancerous invasions long after the initial treatment.

The research is yet to be published, which means it hasn't been peer-reviewed (vouched for by scientists outside of the study), and is tough to evaluate. But the data Riddell is reporting is indeed impressive. In one study, the therapy eliminated all symptoms in 94 percent of participants with acute lymphoblastic leukemia, with other blood cancers showing response rates greater than 80 percent. More than half the subjects reportedly experienced complete remission.

And these patients are ones who seemed sick beyond all hope.

"We have very high rates of complete responses in patients that have failed all other conventional therapies, including bone marrow transplantation," Riddell said during the briefing.

But the BBC reports that seven of the patients had immune responses so severe they ended up in intensive care — and two of those patients died as a result.

These risks are the biggest hurdle for immunotherapy to overcome. But even ignoring the potentially fatal side-effects, which Riddell hopes could be avoided by using lower doses of the therapy, the treatment has a long way to go before we can hail it as a catch-all cure for cancer. For now, it has only been used to treat cancers of the blood.

Not even the excited researchers behind the findings really think this will be a cancer "cure." What they hope is that their therapy can finally usher immunotherapy into the ranks of standard cancer treatment — something that could be used routinely alongside chemotherapy, radiotherapy and surgical interventions.

The team will keep working on ways to make their technique safer and more effective for all types of cancer. And when their results are formally published, other researchers can assess just how revolutionary the therapy truly is.

Read More: