Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares in Puma Biotechnology (PBYI -7.14%) collapsed by more than 15% earlier today after abstracts to be presented at the upcoming American Society of Clinical Oncology meeting were released.

So What: The abstracts include data on Puma Biotechnology's neratinib, or PB272, a cancer-fighting drug that is the company's lead product candidate.

Specifically, abstract #508 includes a summary of neratinib's phase 3 trials in early stage HER2+ breast cancer patients. In the placebo-controlled study, patients that had been previously treated with Roche Holdings' top-selling Herceptin were given neratinib in a bid to boost the number of people who are disease-free at the two-year mark.

The abstact shows that 93.9% of patients in this trial were disease-free after two years, which was only slightly better than the 91.6% rate for those receiving the placebo.

Now What: The small advantage in the neratinib arm of this study appears to be less than what industry watchers were hoping for, but investors should remember that breast cancer is the second leading cause of cancer death among women and that the need for new treatment options that extend patient lives longer is significant. Further, while the advantage is tepid, the study will continue to evaluate patients for five years, and the five-year findings could improve upon, confirm, or fall short of the two-year results.

Additionally, investors also need to remember that neratinib is being evaluated in additional studies, including a phase 2 trial evaluating it as a first-line treatment in HER2+metastatic breast cancer, as well as in HER2 mutated metastatic non-small cell lung cancer.

Source: Puma Biotechnology,

Neratinib is, however, Puma Biotechnology's only pipeline candidate, so the company's success or failure is tightly tied to its potential approval. For that reason, Puma Biotechnology is best suited for investors able to withstand a high degree of risk and potential losses. Although I don't currently own Puma Biotechnology shares, the recent drop could offer an intriguing opportunity that's worth considering.