When a company announces it will begin Phase III testing of a drug candidate, investor expectations tend to inflate. Taking the Phase III designation at face value, however, can be dangerous if a company has not done enough early-stage testing to confidently predict success in "pivotal" trials. On the other hand, for some indications additional testing prior to Phase III may not provide enough incremental information to justify the time and expense of running smaller trials.

ImClone Systems Inc. is taking the latter view with its BEC2 cancer vaccine. After Phase I testing in 15 patients with small cell lung cancer and 135 with melanoma, IMCL and partner Merck KGaA (Darmstadt, Germany) have entered Phase III testing in 800 patients with limited SCLC. Limited SCLC is restricted to the thorax, while extensive SCLC has metastasized outside the thoracic cavity.