Green Light

Olaparib and BSI-201

These compounds, which inhibit a DNA repair enzyme called poly–ADP-ribose polymerase (PARP), showed benefits in early clinical trials, including shrinkage of tumors lacking known drug targets, such as estrogen receptors.

Rasagiline

This drug, which inhibits the breakdown of dopamine and is currently used to ease symptoms of Parkinson's disease, got a major boost thanks to clinical trials that suggested it could substantially delay progression of the illness.

Benlysta

In the first ever phase 3 trial for end-stage lupus, this monoclonal antibody unexpectedly improved disease indicators, opening the way for long-awaited therapies.

Glatiramer acetate (Copaxone)

This synthetic amino acid polymer was previously employed for the treatment of relapsing-remitting multiple sclerosis. Its use has now been extended to treat early, isolated neurologic episodes associated with multiple sclerosis, thanks to its newly demonstrated efficiency in delaying attack onset.

Yellow Light

Avastin

This antibody, which blocks blood vessel growth, was approved in the US as a treatment for glioblastoma and renal cell carcinoma. However, it failed in trials against early-stage colon cancers. Reports have also suggested that targeting blood vessel growth factors might promote cancer metastasis in certain circumstances.

Denosumab

Several clinical trials tested this antibody, which counteracts bone loss. Although a US Food and Drug Administration committee recommended its approval for osteoporosis treatment, it recommended against approval of its preventive use—and its use to treat bone loss in certain cancer cases—until more data are available.

GRNOPC1

Regulators approved clinical trials of this human embryonic stem cell therapy in patients with spinal cord injury. But Geron, the company developing the treatment, temporarily delayed the trial, owing to the detection of microscopic spinal cysts in some rodent tests of the therapy.

GDC-0449

Clinical studies showed that this cell signaling inhibitor can slow the growth of aggressive brain tumors. This success, however, was followed by reports of drug resistance mutations in subjects, tempering hopes for broad anticancer use.

Red Light

Prochymal

Despite receiving fast-tracked approval, this adult stem cell therapy did not yield the expected results in phase 3 trials against two types of severe graft-versus-host disease, and other prospective applications might also need reevaluation.

Desmoteplase

A thrombolytic agent derived from vampire bat saliva, this drug was purported as a treatment for acute ischemic stroke after the success of phase 2 testing. But the results of a phase 3 study showed no disease benefits, stalling further development.

Pactimibe

This treatment was intended to prevent atherosclerosis by inhibiting the buildup of cholesterol inside cells, but advanced clinical trials showed that it might actually promote symptoms and increase cardiovascular disease risk.

Bextra

Pfizer, the company manufacturing this controversial COX-2 inhibitor, reportedly agreed to pay $2.3 billion to settle allegations that it illegally marketed this painkiller for unapproved uses.