The Drug Hunters Read online

  Copyright © 2017 by Donald R. Kirsch and Ogi Ogas

  All rights reserved. No part of this book may be reproduced in any manner without the express written consent of the publisher, except in the case of brief excerpts in critical reviews or articles. All inquiries should be addressed to Arcade Publishing, 307 West 36th Street, 11th Floor, New York, NY 10018.

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  Library of Congress Cataloging-in-Publication Data

  Names: Kirsch, Donald R., 1950– author. | Ogas, Ogi, author.

  Title: The drug hunters : the improbable quest to discover new medicines / Donald R. Kirsch, PhD and Ogi Ogas, PhD.

  Description: First edition. | New York : Arcade Publishing, [2017]

  Identifiers: LCCN 2016034624 | ISBN 9781628727180 (hardback) | ISBN 9781628727197 (ebook)

  Subjects: LCSH: Drugs—Research—History. | Pharmacology—History. | BISAC: SCIENCE / History. | MEDICAL / Pharmacology. | MEDICAL / History. | BIOGRAPHY & AUTOBIOGRAPHY / Medical.

  Classification: LCC RM301.25 .K57 2017 | DDC 615.1072—dc23 LC record available at https://lccn.loc.gov/2016034624

  Cover photo: Slobodan Cedic

  Printed in the United States of America

  Contents

  Introduction: Searching the Library of Babel

  1 So Easy a Caveman Can Do It

  The Unlikely Origins of Drug Hunting

  2 Countess Chinchón’s Cure

  The Library of Botanical Medicine

  3 Standard Oil and Standard Ether

  The Library of Industrial Medicine

  4 Indigo, Crimson, and Violet

  The Library of Synthetic Medicine

  5 The Magic Bullet

  We Figure Out How Drugs Actually Work

  6 Medicine That Kills

  The Tragic Birth of Drug Regulation

  7 The Official Manual of Drug Hunting

  Pharmacology Becomes a Science

  8 Beyond Salvarsan

  The Library of Dirty Medicine

  9 The Pig Elixir

  The Library of Genetic Medicine

  10 From Blue Death to Beta Blockers

  The Library of Epidemiological Medicine

  11 The Pill

  Drug Hunters Striking Gold Outside of Big Pharma

  12 Mystery Cures

  Discovering Drugs Through Blind Luck

  Conclusion: The Future of the Drug Hunter

  The Chevy Volt and the Lone Ranger

  Appendix

  Classes of Drugs

  Notes

  Bibliography and Suggested Readings

  Index

  Introduction

  Searching the Library of Babel

  The Library of Babel

  “By this art you may contemplate the variations of the 23 letters….”

  —Jorge Luis Borges, “The Library of Babel”

  In the deep mists of prehistory, everybody was a drug hunter. Our parasite-infested, malady-ridden ancestors chewed every new root and leaf they chanced upon, hoping to unleash some fortuitous benefit that might ameliorate their afflictions—and praying they did not perish from their blind experimentation. Through sheer serendipity, some fortunate Neolithic souls stumbled upon substances with medicinal properties, including opium, alcohol, snakeroot, juniper, frankincense, cumin, and—apparently—birch fungus.

  Sometime around the year 3300 BC, a solitary man, cold, ill, and mortally wounded, struggled through the high peaks of the Ötztal Alps in Italy until he collapsed in a crevasse. Here he lay frozen for more than five thousand years until hikers stumbled upon his ice-mummified corpse in 1991. They dubbed him Ötzi. When Austrian scientists thawed out this Ice Age hunter, they discovered his intestines had been infested with whipworms. At first the researchers remarked that Ötzi and his contemporaries most likely suffered the indignities of this painful parasite without any hope for relief. A second discovery prompted them to revise their convictions.

  Attached to Ötzi’s bearskin leggings were two hide strips, each knotted around a rubbery white lump. These strange bulbs turned out to be fruiting bodies of the birch polypore, a fungus with antibiotic and anti-hemorrhaging properties. It also contains oils that are toxic to whipworms. Ötzi’s hide-knotted mushrooms are quite likely the oldest medicine kit ever found. The Iceman’s medicines did not have high potency or efficacy—but they worked. The existence of a five-thousand-year-old anti-worm drug (what pharmacologists would call an antihelminthic) reminds me of something my PhD advisor used to say: “When you see a dog walking on its hind legs, you are not impressed by his grace or agility but rather by the fact he can do it at all.”

  Ötzi’s remarkable birch fungus embodies a simple truth about humankind’s quest for medicine. This Neolithic remedy did not arise from clever innovation or rational inquiry. No Stone Age Steve Jobs engineered this antihelminthic out of the visionary workings of his mind. No, Ötzi’s drug was the product of sheer unadulterated luck. All prescientific drug hunting advanced through simple trial and error.

  And today? As Pfizer, Novartis, Merck, and other Big Pharma conglomerates spend billions of dollars on state-of-the-art drug hunting laboratories, you might guess that most blockbuster drugs are the fruits of meticulously planned drug engineering projects where the role of trial-and-error has been replaced with informed scientific execution. Not so. Despite the best efforts of Big Pharma, the prime technique of the twenty-first-century quest for medicine remains the same as it was five millennia past: painstakingly sampling a mindboggling variety of compounds and hoping that one of them, just one, proves out.

  Over the course of my nearly four-decade career as a drug hunter, I’ve learned firsthand that new medicines are often discovered by routes that are wildly circuitous or entirely fortuitous—or both. The professional drug hunter is kin to the professional poker player: possessing enough knowledge and skill to tilt the game in his favor at crucial moments but always at the mercy of the shuffle of the cards.

  Consider rapamycin. In the 1970s, biologist Suren Sehgal was working for Ayerst Pharmaceuticals looking for a new drug to treat common fungal infections such as Candida vaginitis and athlete’s foot. After sampling tens of thousands of compounds, Sehgal discovered a novel antifungal compound that originated in a soil microorganism found on Easter Island. He named the drug rapamycin after Rapa Nui, the aboriginal name for the remote Pacific island.

  Sehgal tested rapamycin on animals and found that it wiped out any malevolent fungi. Unfortunately, the drug also suppressed the animals’ immune system. If you are trying to eliminate an infection, especially a fungal infection, it is crucial for the immune system to work effectively and in concert with an antifungal medicine. This unfortunate side effect proved to be insurmountable, and the Ayerst executives decided to ditch rapamycin and move on.

  But Sehgal did not want to give up. He knew that another antifungal compound, cyclosporine, was being developed for a very different use—as an organ transplant therapy. Like the Easter Island drug, cyclosporine also produced immunosuppressive effects, but this was a desirable property for a post-transplant drug because it helps prevent the body from rejecting
the new organ. Sehgal reasoned that rapamycin might also be useful as an anti-rejection therapy.

  Unfortunately, his employer (which by that time had merged with another company—a frustratingly common occurrence in my industry) did not possess an immune suppression research program, and since the new management team was not interested in organ transplants they dismissed Sehgal’s proposal out of hand. But Sehgal, a seasoned drug hunter, was well aware of one of the most reliable facts about Big Pharma: rapid executive turnover. He bided his time. Whenever a new management team assumed control over the pharmaceutical research, he reintroduced his proposal to test rapamycin as an organ transplant therapy.

  On the third or fourth such occasion, Sehgal’s boss became annoyed by what he perceived as Sehgal’s incessant nagging in the pursuit of a futile pet project. His boss ordered him to take his culture of Easter Island bacterium, dump it in an autoclave, and hit the sterilize button. This would destroy the microorganism once and for all, along with Sehgal’s dreams of a transplant drug—or at least, that’s what his boss hoped. Sehgal did comply with his manager’s demands … but only after taking a rapamycin culture home with him and storing it in his freezer, perhaps squeezing it between his veal cutlets and frozen peas.

  Sehgal’s gamble paid off. Exactly as he hoped, his boss soon moved on to another job and yet another management team took the reins. And once again, Sehgal pitched rapamycin as an anti-rejection drug. This time, his pitch worked. The new execs gave his long-mothballed project the green light. Sehgal yanked the culture back out of his kitchen freezer, re-created the drug, then tested it on transplants in animals … success! Finally, he tested it on actual transplant patients … victory! In 1999—about twenty-five years after Sehgal first discovered it—the Easter Island anti-fungal drug was finally approved as an immunosuppressive agent by the FDA. Today it is one of the most commonly used anti-rejection therapies. It is also used as a coating for coronary artery stents to increase their longevity, a surprising outcome for a drug that was originally intended to fight athlete’s foot and yeast infections.

  Or perhaps it is not so surprising at all. After spending my entire career searching for new medicines, I’ve learned that the only sure thing in the drug hunting business is that you almost never end up with the exact drug you started stalking. The vast majority of my colleagues, all educated at top-flight research universities and working at posh laboratories festooned with high-tech gear, have spent their entire careers groping through the labyrinth of bio-active molecules without ever finding a new compound that safely and effectively improves human health.

  The professor who trained me in pharmacology, an MD, once told me that 95 percent of the time a patient visits a physician he will not actually be helped by the doctor. In most cases, either the patient’s body will heal itself without needing the doctor’s intervention or the disease will be untreatable, rendering the physician powerless. In his view, the physician has the ability to make a meaningful difference to his patients only 5 percent of the time. While that may seem low, those are fantastic odds compared to the ones faced by the drug hunter.

  Only about 5 percent of a scientist’s ideas for a drug discovery project get funded by management. Of these, only 2 percent end up producing an FDA-approved medicine. That means a drug hunting scientist can only expect to make a difference about one-tenth of 1 percent of the time. Finding new drugs is so challenging, in fact, that it has led to a crisis in the pharmaceutical industry. Big Pharma companies are becoming increasingly frustrated with the massive research expenditures necessary to come up with new drugs—an average of about $1.5 billion and fourteen years for each FDA-approved drug—and the exasperating fact that the vast majority of their endeavors don’t produce a usable drug. Executives at Pfizer recently told me they are thinking about getting out of the drug-discovery industry entirely. Instead, they want to be in the drug acquisition industry: they would prefer just to buy drugs that other people have invented. Think about that. Finding new drugs is so formidable that one of the oldest, most talented, and wealthiest drug makers—the largest drug maker in the world, in fact—would rather let other people deal with the problem.

  So why is the “degree of difficulty” of finding new drugs so much greater than, say, landing a man on the moon or designing an atomic bomb? The moon shot and the Manhattan Project employed well-established scientific equations, engineering principles, and mathematical formulas. They were formidable and grueling endeavors, to be sure, but at least the researchers possessed clear scientific road maps and mathematical compasses to guide them. The moon shot engineers knew with certainty the distance from the Earth to the moon, and how much fuel was needed to get there. The Manhattan Project scientists knew that matter could be turned into city-obliterating energy according to E=mc2.

  In contrast, the core challenge of designing a new drug—the trial-and-error screening of immense numbers of candidate compounds—is a task not guided by any known equations or formulas. While an engineer knows if his bridge will bear weight before he ever lays a girder down, a drug hunter has no clear idea how a particular drug will work until a human subject actually ingests it.

  In the mid-nineties, chemists at Ciba-Geigy (now a part of Novartis) calculated the total number of possible drug compounds in our universe: 3 x 1062. When it comes to characterizing the size of a number, some numbers are big, some are enormous, and some are so incomprehensibly, inconceivably large that they might as well be infinity. The number 3 x 1062 falls into that third category. If you were able to test one thousand compounds every second to see if any of them could serve as an effective remedy for a particular malady—say, breast cancer—by the time our sun burned out you would still have not made a measurable dent in the total number of breast cancer-fighting drug possibilities.

  There is a story by the blind Argentinean author Jorge Luis Borges that I think perfectly captures the central challenge of drug hunting. In “The Library of Babel,” Borges imagines that the universe is a library consisting of an infinite number of hexagonal rooms that extend forever in every direction. Each room is filled with books. Each book contains a random arrangement of letters, and no two books are the same. Once in a while, purely by chance, a book contains an entire readable sentence, such as “The gold is in the mountain.” But, as Borges puts it, “For every rational line or forthright statement there are leagues of senseless cacophony, verbal nonsense, and incoherency.”

  Nevertheless, the library must contain books that, purely by chance, are filled with legible life-changing wisdom. Such books are known as “Vindications.” In Borges’s fantasy, solitary searchers known as librarians wander endlessly through the library, hoping to find these Vindications. Most librarians wander through the endless hexagons in vain, spending their life coming across nothing but nonsense. But Borges notes that there are librarians who, through good fortune or sustained force of will, have managed to discover a Vindication.

  Similarly, every possible drug is contained somewhere in the vast theoretical library of chemical compounds. There is a molecular configuration that will safely destroy ovarian cancer, another that will halt the corrosive advance of Alzheimer’s, another that will cure AIDS—or maybe they do not exist at all. There is no way to know for sure. Modern drug hunters are like Borges’s Babelian librarians, forever questing for life-changing compounds and always suppressing their secret fear that the vindicating medicines may never be found.

  The problem, ultimately, is the human body. Our physiological activity is not a closed, well-defined system like rocket propulsion or nuclear fission. It is an open and unfathomably arcane molecular system with innumerable undefined relationships among its components, rendered even more abstruse by the fact that each person’s body has their own idiosyncratic structure and dynamics. We only understand a tiny fraction of these physiological relationships and have not yet deciphered how most of our body’s basic molecular components actually work. Complicating matters still further is the fact that ea
ch individual has her own idiosyncratic genetic and physiological architecture, so that each person’s body operates slightly (or extremely) differently. Even more daunting, despite tremendous advances in our understanding of cells and tissues and organs, we simply cannot precisely predict in advance how a given chemical compound will interact with a given molecule in a living body. In fact, it is impossible to know with certainty if a particular disease possesses what pharmacologists call a “druggable protein” or a “druggable target”—some specific protein associated with a pathology that can be influenced by a chemical agent.

  Designing an effective drug requires two things: the right compound (the drug) and the right target (the druggable protein). The drug is like a key that turns the protein lock to start the ignition on a physiological engine. If a scientist wants to intentionally influence a person’s health in a specific way—to reduce depression, relieve itching, treat food poisoning, or produce any other health benefit—she must first identify a target protein that influences the relevant physiological processes in the human body or that, conversely, interferes with the physiological processes of a pathogen.

  For example, Lipitor acts upon HMG-CoA reductase, the protein controlling the rate of the body’s synthesis of cholesterol. Penicillin, in contrast, shuts down peptidoglycan transpeptidase, a protein required to synthesize the (essential) cell wall of a bacterium. But finding the drug key that will turn a protein lock … As Hamlet would say: Ay, There’s the rub! This is the daunting challenge for the drug hunter. Despite the humbling odds, some drug hunters, such as Suren Sehgal, through unwavering resolution or outrageous fortune, through individual genius or far-flung collaborations, have stumbled upon their Vindications.

  The term drug hunters have bestowed upon the process of systematically searching through a library of compounds is screening. The prehistoric screening method consisted of snatching every new berry or leaf you came across and snorting it, smearing it, or swallowing it. After unknowable eons of our ancestors randomly sampling the natural landscape, in 1847 the first drug was discovered using a reasonably scientific method of screening. At the time, physicians were using ether as a surgical anesthetic, prompting them to reason that there could be other chemical compounds similar to ether that might work even better. Ether had a few obvious shortcomings—it irritated patients’ lungs and had an unfortunate tendency to explode—so physicians knew there would great clinical value for a new anesthetic without these issues.