Twenty-five years ago this month, the U.S. Food and Drug Administration approved Gleevec — known generically as imatinib — to treat chronic myeloid leukemia, a decision that fundamentally reshaped the way doctors understand and treat cancer. What followed was a cascade of targeted therapies that have extended and improved millions of lives worldwide.
In May 2001, the FDA approved Gleevec (imatinib) in a record 72 days under its accelerated approval pathway, signaling the agency's recognition that the drug represented something genuinely new in oncology. Developed in part through the sustained advocacy of Dr. Brian Druker, director of the Knight Cancer Institute at Oregon Health & Science University, Gleevec became a landmark moment in the shift from broadly toxic chemotherapy toward precision, targeted medicine.
Before Gleevec, patients diagnosed with chronic myeloid leukemia (CML) faced grim prospects. The standard of care involved interferon-alpha injections and, for younger patients, bone marrow transplants — treatments that were difficult to tolerate and often only marginally effective. A CML diagnosis carried a median survival measured in years rather than decades.
Gleevec worked differently. Scientists had identified that CML is driven by a specific genetic abnormality — the so-called Philadelphia chromosome — which produces an abnormal protein called BCR-ABL that instructs cancer cells to grow uncontrollably. Rather than attacking all rapidly dividing cells indiscriminately, as traditional chemotherapy does, Gleevec was engineered to block that specific protein. The results were striking: in clinical trials, the vast majority of patients achieved complete cytogenetic responses, meaning the cancerous cells became undetectable.
The drug's impact extended far beyond CML. Gleevec demonstrated that if researchers could identify the molecular driver of a cancer, they could potentially design a drug to target it precisely — a concept that now underpins a broad class of medications used against lung cancer, breast cancer, melanoma, and many others. Drugs like Herceptin, Keytruda, and the BRAF inhibitors used in melanoma treatment all owe an intellectual debt to the proof of concept Gleevec established.
"It really was a watershed moment," oncologists have noted in the years since. Where cancer had long been categorized primarily by the organ in which it appeared — lung cancer, colon cancer, leukemia — Gleevec helped accelerate a reconceptualization of cancer as a disease of genetic mutations, regardless of where in the body it originates.
For patients, the practical transformation has been profound. Many CML patients today take a once-daily oral pill and can expect near-normal life expectancy, a contrast so stark from the pre-Gleevec era that researchers have described it as converting a fatal disease into a manageable chronic condition.
Challenges remain. Gleevec's annual cost — which rose to tens of thousands of dollars in the United States before generic versions became available — sparked ongoing debate about pharmaceutical pricing and access to life-saving medications. Generic imatinib is now widely available, but the pricing patterns established during Gleevec's patent period have been cited as a model, for better and worse, by the broader pharmaceutical industry.
The drug also does not work for everyone. A subset of CML patients develop resistance, prompting the development of second- and third-generation alternatives such as dasatinib and nilotinib. And while Gleevec's success inspired a wave of targeted therapy research, many cancers have proven far more genetically complex and resistant to single-target approaches.
Nevertheless, as oncology marks a quarter-century since that approval, Gleevec's legacy is largely one of transformation — a molecule that proved a new paradigm was possible and set a generation of researchers on the path to pursue it.
Analysis
Why This Matters
- Gleevec's 25th anniversary is not merely a medical milestone — it represents the moment modern precision oncology was validated, directly affecting the treatment approaches now used for dozens of cancers affecting millions of patients globally.
- The drug's commercial history also helped shape current debates over pharmaceutical pricing, patent exclusivity, and access to essential medicines, debates that remain unresolved in the United States and internationally.
- The targeted therapy revolution Gleevec launched continues to accelerate, with implications for how diseases beyond cancer — including some genetic and autoimmune conditions — may eventually be treated.
Background
For most of the 20th century, cancer treatment relied on surgery, radiation, and chemotherapy — the last of which works by killing rapidly dividing cells, a mechanism that damages healthy tissue alongside tumours and causes severe side effects. The discovery of oncogenes and tumour suppressor genes in the 1970s and 1980s raised the theoretical possibility of more precise interventions, but translating that science into approved drugs proved slow and difficult.
The Philadelphia chromosome — an abnormality found in the cancer cells of nearly all CML patients — was identified as far back as 1960, and the BCR-ABL fusion protein it produces was characterised in the 1980s. Dr. Brian Druker at Oregon Health & Science University became a central figure in pushing pharmaceutical company Novartis to develop and test what would become imatinib, overcoming significant institutional resistance along the way. Early clinical trials in the late 1990s produced response rates that were, by oncology standards, extraordinary.
The FDA's accelerated 72-day review in 2001 reflected both the strength of the clinical data and the urgent need of patients with few alternatives. The approval came with significant public attention and is widely taught in medical and public health programmes as a case study in translational research — the process of moving discoveries from the laboratory into clinical practice.
Key Perspectives
Oncologists and researchers: Broadly regard Gleevec as one of the most important drug approvals in modern medical history, crediting it with validating the targeted therapy model and generating a research framework that has produced dozens of subsequent precision medicines.
Patients and advocacy groups: CML patients in particular have experienced a dramatic improvement in outcomes, with many describing the drug as life-saving. Patient groups have also been vocal critics of the high list prices charged for Gleevec and its successors during periods of patent exclusivity, arguing that publicly-funded research contributions justified earlier or more affordable access.
Critics and health economists: While celebrating the science, critics point to Gleevec as a case study in how pharmaceutical companies can set and sustain high prices for essential medicines. Novartis's pricing decisions for Gleevec, and the industry's subsequent pricing of other targeted therapies, have fuelled legislative and regulatory debates about drug affordability in the United States and elsewhere.
What to Watch
- Ongoing clinical research into next-generation targeted therapies and whether they can replicate Gleevec's success across harder-to-treat cancers with more complex genetic profiles.
- U.S. and international policy developments around drug pricing reform, where Gleevec frequently appears as a reference point in negotiations and legislation.
- The expanding use of genomic sequencing in routine oncology care, which would accelerate the identification of targetable mutations in more patients — a direct extension of the paradigm Gleevec established.