The oncology market has witnessed remarkable growth during the past five years and is poised for even greater growth during the next three years. The total oncology market is expected to reach more than US $32 billion in size by 2005, driven by factors including a continued trend towards aggressive chemo-therapy, active patient populations that demand access to the latest therapies, and continued favourable pricing due to high unmet need. Moreover, nearly all of the major pharmaceutical companies have active oncology development programmes, and for biotech firms, oncology projects dwarf all other R&D programmes. In spite of all this positive momentum for the oncology market, pharmaceutical and biotech companies who play in this area face the crucial issue of late-stage clinical attrition. Even with more than 500 oncology compounds in development, only a few achieve regulatory approval each year and there are only ~90 approved oncology drugs in the US today. A number of high-profile clinical and regulatory setbacks, such as the cases of gefitinib (Iressa; AstraZeneca) and cetuximab (Erbitux; Imclone), highlight the challenges that oncology drug candidates are facing. The dramatic unpredictability of single-arm, uncontrolled Phase II trials in cancer helps explain why anti-cancer drug development is so challenging. Although oncology projects have higher average success rates than other therapeutic areas in early-stage trials (that is, Phase I and II), these projects have a lower average success rate than other therapeutic areas at Phase III. Oncology projects are riskier than those in other therapeutic areas, precisely at the stage of clinical development in which costs are highest. Moreover, early development trials do not seem to be very predictive of success rates for later development, which could mean that the industry might soon face a big series of disappointments in the form of failed drug candidates. Several key factors drive the high rate of attrition we are seeing with oncology compounds: market pressures, challenges with the underlying science and changes in the regulatory environment. On the market side, companies are under significant pressure to reach for the broadest possible label on first regulatory approval to capture a broad market. As such, many initial label applications target one or more of the 'big four' tumour types: breast, prostate, lung and colon cancer. The challenge in doing this is that the standard clinical practice for these tumours often involves multiple drug cocktails of cytotoxic chemother-apy agents. So, for new therapies, clinical trials …