What happened

Shares of CRISPR Therapeutics (CRSP 0.69%) gained over 42% last month, according to data provided by S&P Global Market Intelligence. The company provided the first glimpse of CTX001, a therapy based on CRISPR gene editing, in sickle cell disease and transfusion-dependent beta-thalassemia (TDT). While the preliminary results were from only two patients -- one in each indication -- they demonstrated promising potential for the approach. 

Investors cheered the update, which was the first from any company developing CRISPR-based tools. The news sent several gene-editing stocks higher. Shares of Editas Medicine and Intellia Therapeutics rose as well, although super-early success for CTX001 means next to nothing for industry peers. More meaningful might be the implications for Vertex Pharmaceuticals (VRTX -0.43%), the collaboration partner of CRISPR Therapeutics for CTX001, which could be handsomely rewarded for its early bet on the gene-editing technique.

An individual sitting with a doctor

Image source: Getty Images.

So what

CRISPR Therapeutics reported that after one dose of CTX001, the individual with TDT was transfusion independent through the nine-month mark. The patient had averaged 16.5 blood transfusions per year in the two years prior to the clinical trial.

Similarly, after one dose of CTX001, the individual with sickle cell disease was free of vaso-occlusive crises (painful blockages of small blood vessels caused by abnormally shaped blood cells) at the four-month mark. The patient had averaged seven such events in the two years prior to the study. Both patients achieved promising results for an important biomarker as well.

Now what

How excited are investors? Well, CRISPR Therapeutics announced a public stock offering days after providing the clinical update, but after briefly tumbling, shares actually shook off the dilution concerns and continued ascending through the end of the month. The business ended September with over $629 million in cash and raised up to $315 million from the November offering. 

Simply put, the early update from CTX001 is about as good as investors could have hoped for, although the results are obviously very preliminary. The studies are designed to enroll dozens of patients and track them for two years. Will the results prove durable? Will adverse events or other safety issues crop up as the studies mature? Investors will have to remain patient, but CRISPR Therapeutics remains the top gene-editing stock.