The Philadelphia Chromosome: A Mutant Gene and the Quest to Cure Cancer at the Genetic Level

The Philadelphia Chromosome: A Mutant Gene and the Quest to Cure Cancer at the Genetic Level


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Philadelphia, 1959: A scientist scrutinizing a single human cell under a microscope detects a missing piece of DNA. That scientist, David Hungerford, had no way of knowing that he had stumbled upon the starting point of modern cancer research— the Philadelphia chromosome. It would take doctors and researchers around the world more than three decades to unravel the implications of this landmark discovery. In 1990, the Philadelphia chromosome was recognized as the sole cause of a deadly blood cancer, chronic myeloid leukemia, or CML. Cancer research would never be the same.

Science journalist Jessica Wapner reconstructs more than forty years of crucial breakthroughs, clearly explains the science behind them, and pays tribute—with extensive original reporting, including more than thirty-five interviews—to the dozens of researchers, doctors, and patients with a direct role in this inspirational story. Their curiosity and determination would ultimately lead to a lifesaving treatment unlike anything before it.

The Philadelphia Chromosome chronicles the remarkable change of fortune for the more than 70,000 people worldwide who are diagnosed with CML each year. It is a celebration of a rare triumph in the battle against cancer and a blueprint for future research, as doctors and scientists race to uncover and treat the genetic roots of a wide range of cancers.

Product Details

ISBN-13: 9781615190676
Publisher: Experiment, The
Publication date: 05/14/2013
Pages: 320
Product dimensions: 6.20(w) x 9.10(h) x 1.20(d)

About the Author

Jessica Wapner is a freelance writer focused mainly on healthcare and medicine. Her work is published in The New York Times, Scientific American, Slate, Science, Nature Medicine, Ode, and Psychology Today. Her writing on cancer research and treatment also appears in the science magazines Oncology Business Review, Cure, and CR. Her blog, Work in Progress, is part of the PLoS Blog Network and focuses on the ethics and economics of drug development. She was the founding managing editor of two review journals, Clinical Advances in Hematology & Oncology and Gastroenterology & Hepatology, and also served as editor for Oncology Spectrum. She lives in Beacon, New York, with her husband and two young children.

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David Hungerford could not believe what he was seeing.

He hovered over a microscope, turning the wheels this way and that to ensure the best view. A small glass slide was illuminated from below. It held a single cell that had been expanded and then stopped in the middle of reproducing, its forty-six chromosomes on full display. He checked and rechecked, and was absolutely certain: One of the chromosomes was too short.

It was 1959, the year that the genetic root of Down syndrome — an extra copy of one chromosome — had been found. The field of genetic research was almost nonexistent. The 1956 confirmation of the standard number of chromosomes housed in the human cell — forty-six, in twenty-three pairs, one set inherited from each parent — hinted at something impossible to grasp, a continent on a horizon too distant to see with the tools of the day. Even though James Watson and Francis Crick had made their famous discovery of the helical structure of DNA in 1953, the search for connections between DNA and disease had only just begun. Around the world, laboratories were just starting to toy with the kind of technology needed to explore genetic matter. Genes were units of heredity, a way for traits to be passed on from one generation to the next, including deficiencies. But how disease could possibly be linked to DNA was entirely unknown. Phrases like "genetic mutation" or "chromosomal abnormality" were not part of the vernacular yet because there was no need for such language.

And so it was that David Hungerford, a young scientist hovering over a microscope, was stunned by what he was seeing through the lenses. This was a man who knew how chromosomes should look. Camera-equipped microscopes were hot laboratory commodities in the 1950s, and Hungerford, an avid photographer, had gotten a job working with one in a Philadelphia cancer research center. He spent countless hours looking at the starfish-shaped chromosomes of the drosophila fly, training his eyes to see the fine banding patterns within. He was one of a handful of people alive at the time who could have spotted an anomaly among a blurry, inky array of chromosomes.

So it may have been inevitable that he'd ended up working with Peter Nowell, a doctor also in his early thirties doing cancer research across town at the University of Pennsylvania. In 1956, Nowell had accidentally stumbled upon a new method for seeing chromosomes inside cells. He had been studying blood cells from leukemia patients, his work following the usual approach of the day: rinsing the cells and staining them with a bluish-purple dye.

Science had come a long way in its ability to peer inside cells, the basic structural units inside every living thing, since they were first spotted by microscope in 1665. That discovery led to others, which led to the creation of cell theory, the notion that all living things are made of cells, and that new cells are made when old cells divide. But the cutting-edge techniques for seeing the inner clockwork were still rudimentary, calling for the scientist to squash a drop of cells on a covered glass slide with the thumb in order to put pressure on the cells. The squash was supposed to burst the cell, spilling out its gene-filled middle. But the approach failed as often as it succeeded, leaving behind broken cell fragments that were useless to researchers. People were frustrated with the technique, which wasted precious time and resources.

One day Nowell took a shortcut around the usual scientific procedure. "Pete was in a hurry, as young men tend to be," Alice Hungerford, David's wife, would recount years later. Instead of following a more rigorous cleaning method, Nowell washed a sample of white blood cells under some tap water. He dropped the rinsed cells onto the slide and was amazed by what he saw through the microscope. The tap water, it turned out, was hypotonic — a low-pressure solution that caused the cells to swell, like a deflated raft being blown up with too much air.

With the cells ballooned like that, Nowell could see something else equally surprising. It turned out that a bean extract he'd applied to help clot the red blood cells (making them easier to remove from a sample) had also stimulated division in the white cells. Captured in the midst of dividing, the cells were at their most expanded. Because the tap water had further expanded the size of the cell, the chromosomes had more room to spread out and were suddenly easier to see and count. No one was looking at chromosomes this way. Nowell hadn't known it was possible. Then again, he knew nothing about genes and had little interest in genetics. But he kept the slide, figuring someone out there might be interested in taking a look.

The genetics community was small then, and the number of people in the Philadelphia area interested in genetic research could be counted on one hand. Hungerford heard about Nowell's slide. The two began working together. For years, Nowell prepared slides that Hungerford would study under the scope. They perfected the hypotonic solution, still used in molecular genetics today, and figured out how to air-dry slides to help the cells spread out even more. But they saw nothing noteworthy.

Then, in 1959, three years after they'd met, there it was: an abnormally small arm of a worm-shaped chromosome inside a cell of a person with CML. With the chromosomes splayed in the squashed cell, Hungerford could clearly see that one was too small. A piece of it was missing. They looked at blood samples from six other CML patients and found the same abnormality.

Stunned, Hungerford snapped the camera shutter. He would not live to see the significance of the picture he'd just taken. In 1959, the effect that a single photograph showing a single mutant chromosome would have on the lives of countless patients and on the future of cancer treatment was entirely unsuspected.

"Until we stumbled over this Philadelphia chromosome, there was really no evidence that cancer might be due to genetic change," Nowell, now 79, said decades later. This photograph would become the lasting portrayal of a moment when everything changed for cancer and medicine as a whole. It was the as-yet unrecognized starting point for the modern era of targeting cancer at its root cause.



At the time of their discovery, David Hungerford was spending about ten hours a day looking at fly chromosomes, and Peter Nowell had just returned to the University of Pennsylvania. Nowell had originally started working in the pathology lab there as a summer job in 1950. A cocky and charismatic med student, Nowell had felt certain that, given the chance, he could "solve this cancer problem" in a matter of months. But that summer he got married, and the Phillies were on their way to winning the pennant, distractions that, he said, delayed his plans to cure cancer.

But those few summer months were enough for Nowell to understand just how vast a territory he'd entered into as a cancer researcher. "I really knew very little about the specifics of things," he would say later. "In those days, it was true of pretty much everybody." He decided to take an internship for a year with a hematologist at a nearby hospital. It was there that he had his first serious education about cancers of the blood — how devastating and how complicated these diseases really were.

There were the leukemias that took over the white blood cells, with chronic versions that progressed slowly and acute versions that led to rapid destruction of the immune system. White blood cells, which fight infections, normally numbered 4,000 to 10,000 per microliter of blood. Leukemia patients typically had counts in the hundreds of thousands per microliter. The lymphomas, Nowell learned, poisoned the lymph, another infection-fighting part of the immune system concentrated primarily in bean-shaped nodes throughout the body. Lymphoma could pass from one node to another, like a fungus spreading through a forest. Multiple myeloma was a cancer of the plasma — the yellow-colored liquid that holds red blood cells, white blood cells, and platelets in suspension as they course throughout the body — filling the marrow with malignant cells, which compromise the immune system and erode bones.

These were the so-called liquid cancers, or hematologic malignancies. For cancer researchers, they were often easier to study because of their accessibility. It was much simpler to draw fluid out from a vein than to cut a patient open to excavate a solid tumor buried deep inside the body. But being able to get at the cancer hadn't led to more significant advances in treatment. When Nowell was in medical school, most types of liquid cancers were still incurable.

On rounds, he saw the victims of these harsh diseases. They brought to life the horrors of cancer more than any squashed cell ever had. A young person getting his first palpable glimpse at death, Nowell saw how shallow he'd been when he first arrived at Penn. Humbled, he realized that cancer was a beast the world had been wrestling for centuries, and against which few meaningful strides had been made.

Then, just when he was feeling a surge of dedication to the long haul of cancer research rise up in him, Nowell was drafted into the military. He was sent to San Francisco to work at the US Radiology Defense Laboratory, where he was assigned to a team studying the potential effects of radiation. The government wanted to know the possible dangers associated with the fallout from nuclear testing in the Pacific. The risks to people included diminished numbers of red and white blood cells circulating in the body in the short term and, in the long term, leukemia and other malignancies. Again, the horrors of cancer were made ever more apparent to him — this time, even more so as he witnessed the man-made devastation.

In 1956, Nowell returned to Penn, as determined as ever to solve this cancer problem.

Hungerford, on the other hand, had no desire to cure cancer. It just wasn't his way as a scientist. He had taken the more scholarly PhD route, and the driving force behind all of his work was a love of observation — to look, to record what he saw, and to share those findings with anyone else who might be interested. Compared with Nowell's passion, Hungerford's approach could seem cold and distant to their colleagues. But Hungerford was happy to record their observations for the simple reason that observations should be recorded. "He just liked to look through the microscope and see the thing," said Alice. He felt no ownership of his ideas, and he had no need for recognition. He just wanted to do the work of science; that was his role in the world. It was what made him feel alive.

Nowell and Hungerford's discovery of "the minute chromosome" was published in 1960. The report consists of three brief paragraphs in a scientific journal, without even the typical list of references that scientific papers have, set indiscriminately among a few other reports of the month. "It's three hundred words," said Emil Freireich, a leukemia doctor responsible for many major therapeutic advances, and a towering figure in the world of cancer medicine. "And it revolutionized everything."

When Nowell and Hungerford published their third scientific paper documenting the truncated chromosome in a large number of patients, with reports from groups at universities around the world confirming the phenomenon, the minute chromosome was renamed the "Philadelphia chromosome" in recognition of the city where it had been discovered.

After scientists across the world found the abnormal chromosome in their own CML cell samples, many set to work on finding other such mutants. At first, researchers thought that this chromosome was the first drop in what would soon become a waterfall of genetic mutations linked to cancer, and, they hoped, some meaningful advancement for cancer treatment. In scientific journals, the chromosome was referred to as Ph, an abbreviation that left space for other mutation discoveries to come — Ph, Ph, and so on — with researchers in other cities then following suit. But further cancer-linked mutations proved elusive. No others were found, in Philadelphia or anywhere else. Ph, as it is still often called, was found in a small percentage of samples from patients with other types of leukemia, acute lymphoblastic leukemia and acute myeloid leukemia (AML), but the link was not nearly as strong as that seen in CML. There was a brief stir over an abnormality spotted by some New Zealand researchers — the "Christchurch chromosome," people called it — but that soon turned out to be a false alarm. Whatever mutations were found appeared much more rarely than the Philadelphia chromosome did in CML. Those tenuous links hardly seemed the stuff of cancer cures.

And so enthusiasm over the Philadelphia chromosome waned, mainly because no one knew what to do with the information. "In the early years, the medical community did not care about human chromosomes," recalled Alice Hungerford, who met David when she took a job in his lab. It was like seeing a bright spot in the night sky with no knowledge of planets and solar systems. Despite the obvious connection between CML and the Philadelphia chromosome, there was very little suspicion of a causative link between genetic abnormalities and cancer. There was no technology to look any further into the mutation. In fact, it wasn't even called a mutation; it was considered a deletion. Nowell and Hungerford resisted the notion that the piece of chromosome was completely gone from the cell. They knew that such a deletion would likely be lethal. But they had no explanation for what else could have happened. A piece of genetic material had vanished. Why had it disappeared? Did the change somehow cause leukemia, or did leukemia somehow cause the change?

These were questions for another decade. Knowing the standard number of chromosomes had enabled geneticists to create a universal number language. But the view afforded by the technology at the time was so coarse that at first Nowell and Hungerford couldn't even tell which chromosome the abnormality was located on. Eventually it became clear that the deletion was from one of the two copies of chromosome 22, but that was still an incomplete description. Chromosome 22 looked an awful lot like chromosome 21 and sometimes even the Y chromosome present in males. Later, methods for staining specific chromosomes would allow for a much more discriminating study. But in 1960, these techniques were unknown. Whatever questions scientists had about the Philadelphia chromosome, there weren't any that could be answered.

Nowell and Hungerford's collaboration also reached a standstill. It was as if they had come together just to find the Philadelphia chromosome, and now, having done so, needed to move on. Nowell continued to pursue cancer research, and would ultimately spend his entire career in the same laboratory. His early success garnered him a rare lifetime government research grant. The money enabled him to pursue cancer research without the pressure to churn out publications or complete grant applications every few years, a highly limiting factor on lab research today. "I had it easy," Nowell recalled toward the end of his years at Penn, his hair as white as his lab coat. "As my wife used to say, I just assumed there was a closet with green pieces of paper in it." Nowell's grant left him free to continue research without worry about making discoveries.

Although he never again struck gold with a serendipitous discovery, Nowell contributed to important theories about how tumors evolve. He was an early adopter of the notion that tumors accrue mutations over time, a key component of modern anticancer drug development. As he put it, cancer works like a tree. A branch off the trunk is the first mutation, and every subsequent twig represents further changes to the DNA. In the end, a cell that started off just a bit different from normal accrues multiple oddities, each one enabling it to better survive in the body, and each one a potential target for a new drug. This phenomenon is at the heart of current cancer research, as scientists sift through the dozens, sometimes hundreds, of genetic abnormalities for the ones that are advancing the deadly cells.

Hungerford's life took quite a different turn. In 1971, he was diagnosed with multiple sclerosis. Not wanting to suffer the pity of his peers, Hungerford kept his disease a secret, telling only Nowell, who had become his friend and now confidant. When Hungerford's treatments and condition diminished his productivity, colleagues and grant reviewers assumed he was either lazy or untalented. His funding gradually decreased, and eventually his lab at Fox Chase Cancer Center, where he'd worked since before meeting Nowell, was shut down. Devastated, Hungerford never stepped behind the microscope again. "He did not pick up a scientific journal after that," says Alice. "It broke his heart." A longtime smoker, Hungerford died of lung cancer in 1993 at the age of 66.


Excerpted from "The Philadelphia Chromosome"
by .
Copyright © 2014 Jessica Wapner.
Excerpted by permission of The Experiment Publishing.
All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.
Excerpts are provided by Dial-A-Book Inc. solely for the personal use of visitors to this web site.

Table of Contents

Author's Note ix

Foreword Robert A. Weinberg xi

Prelude: Down to the Bone, February 2012 1

Part 1 The Chromosome and the Disease, 1959-1990 13

1 The First Clue 15

2 Three Hundred Words 19

3 Investigating a Chicken Virus 25

4 Right Number, Wrong Place 33

5 The Surprising Source of the Chicken Cancer Gene 40

6 Consummate Instigators 49

7 Where the Kinase Hangs the Keys 53

8 A Chemical Amputation 57

9 Stripping Away the Fur and the Fat 64

10 A Funny New Protein 69

11 The First Sign of a Human Cancer Gene 75

12 Spelling Out the Translocation 81

13 "That Word Is Oncogenes" 87

Part 2 Rational Design, 1983-1998 93

14 Becoming a Doctor, and Then a Scientist 95

15 Turning a Protein into a Drug Target 104

16 A Machine with a Virus for a Motor 112

17 Plucking the Low-Hanging Fruit 116

18 A Drug in Search of a Disease 120

19 Two Endings 129

20 Getting Out of Boston 133

21 Killing Cells 138

22 Gain and Loss 147

23 "Not Over My Dead Body Will This Compound Go into Man" 156

Part 3 Human Trials, 1998-2001 173

24 The Quickest Answer 175

25 Getting to 200 Milligrams 181

26 The One Thing They Didn't Have 190

27 Buzz in the Chat Rooms 199

28 Saving Their Own Lives 202

29 A Response Rate of One Hundred Percent 210

30 Good Stressful 213

31 Putting It in Writing 221

32 A Truck load of Data 226

33 The Fathers of Victory 234

Part 4 Aftermath 241

34 A Price to Pay 243

35 Showing a Weakness 247

36 The First Five Years 253

37 The Second Generation 257

38 A Gleevec for Every Cancer 261

Epilogue: Survival Time 270

Glossary 273

References 283

Acknowledgments 291

Index 293

Photo Credits 302

About the Author 303

What People are Saying About This

Siddhartha Mukherfee

“The story of the Philadelphia chromosome is truly the story of modern cancer biology. . . . Jessica Wapner stitches the whole story together with tenacity, diligence (and humor). This is a wonderful, readable, and highly informative book.”
—Siddhartha Mukherjee, Pulitzer Prize-winning author of The Emperor of all Maladies

From the Publisher

“The story of the Philadelphia chromosome is truly the story of modern cancer biology—from the very earliest description of a chromosomal abnormality in cancer cells to the development of a targeted medicine against a formerly lethal type of leukemia. Jessica Wapner stitches the whole story together with tenacity, diligence (and humor). This is a wonderful, readable, and highly informative book.”
—Siddhartha Mukherjee, Pulitzer Prize–winning author of The Emperor of All Maladies

“Jessica Wapner shows us in The Philadelphia Chromosome how the past and the future combine to dramatically change the course of a disease. This beautifully written book is a blueprint for broader healthcare change. A pivotal book.”
—David B. Agus, MD, Professor of Medicine and Engineering, University of Southern California, and author of The End of Illness

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The Philadelphia Chromosome: A Mutant Gene and the Quest to Cure Cancer at the Genetic Level 4.5 out of 5 based on 0 ratings. 2 reviews.
efm More than 1 year ago
Good story of scientific discovery in medicine.
Anonymous More than 1 year ago