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Nature Biotechnology 25, 825–826 (1 August 2007) | doi:10.1038/nbt0807-825

Clinical setbacks for toll-like receptor 9 agonists in cancer

Charlie Schmidt

In June, Pfizer dropped a clinical program in non-small cell lung cancer for PF-3512676, a CpG oligodeoxynucleotide (ODN) drug that activated toll-like receptor 9 (TLR9) of the immune system. While being tested in phase 2 and 3 trials together with a variety of chemotherapy agents, an interim analysis of the two phase 3 trials of PF-3512676 showed it failed to yield clinical outcomes better than those obtained with chemotherapy alone, prompting Pfizer to cut its losses and dump the two phase 2 programs, as well.