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 of Synta Pharmaceuticals (NASDAQ: SNTA), a clinical-stage small-molecule drug developer aimed at treating cancer and chronic inflammatory diseases, soared as much as 21% after announcing positive interim results from its ENCHANT-1 study of experimental metastatic breast cancer therapy ganetespib at the European Breast Cancer Conference.

So what: According to its study design, Synta was evaluating ganetespib over 12 weeks as a single-agent therapy and looking at both efficacy as well as predictive biomarkers across three trial cohorts, including HER2-positive patients, and triple-negative breast cancer patients, or TNBC. The results demonstrated that six of seven patients that were evaluable in the HER2-positive cohort at week three achieved a metabolic response while 18 of 31 in the TNBC arm achieved a metabolic response. For those who were evaluable at week six, four had an objective response and two stable disease in the HER2-positive cohort and two had an objective response, 11 achieved stable disease, and 13 progressed in the TNBC cohort. Synta also points out that one patient in the HER2-positive intent-to-treat group has achieved a complete objective response and has remained on ganetespib for more than 10 months.

Now what: This is more encouraging news for Synta and ganetespib following last week's selection for the investigator-sponsored I-SPY 2 breast cancer trial. Synta obviously has a lot riding on the success of ganetespib, but is also likely to continue to burn through its precious cash in the meantime while it conducts its clinical studies. While ganetespib hasn't given me any reasons to be concerned, it's also not thoroughly wowed me with its results as of yet. For that reason, I'd suggest sticking to the sidelines until we see concrete late-stage results demonstrating ganetespib's efficacy.