This is fresh air, I'm Terry Gross.

COVID has challenged a lot of what researchers thought they knew about how our immune system works.

The key to solving COVID's mysteries likely involves a new understanding of cellular science.

Cellular science is also leading to tools to fight specific types of cells that have gone rogue or become pathological,

while at the same time not attacking healthy cells.

Cancer, HIV, type 1 diabetes, and sickle cell anemia are some of the diseases in which this new approach is being used or as an experimental stages.

My guest said Arthur Mukherjee writes about this new field of cell therapy,

and what we've learned about the immune system in his new book Song of the Cell.

He's an oncologist, cell biologist, and hematologist who treats cancer patients and conducts research in cellular engineering.

In the book, he also writes about the period of his profound depression,

and what he learned about new approaches to electrical brain stimulation that are being tested to treat depression.

Mukherjee won a Pulitzer Prize for his book The Emperor of All Malaties, a biography of cancer.

He's also written about medicine in the New Yorker.

So, Arthur Mukherjee, welcome back to Fresh Air. I learned so much from your new book. Thanks for coming back to our show.

Oh, thank you for having me, Terry.

In the beginning of your book, you write about two cases that reveal how revolutionary, cellular modification and engineering can be used in combating disease, and how it can backfire.

So, I want to start with a case in which it backfired, and the patient was a friend of yours named Sam, at least that's the name you use in the book.

Would you describe how far his cancer had progressed when he was treated with a cellular therapy?

Yes, Sam's case was a very personal case for me, and I began the book with it.

Partly to inject a dose of humility right at the beginning of the book.

Sam had a metastatic melanoma, cancer of melanocytes, skin cells, and it had metastasized to his liver, to his lungs, and to parts of his skin.

And he was treated originally with a surgical resection, but unfortunately after the resection, the cancer was detected to be metastatic.

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