I agree that, IF THE ABSTRACT OF THE 15-MONTH DATA HAD NOT BEEN DISCLOSED, the company would arguably not have an obligation under the securities laws to release data that wasn't as good as the company had hoped. However, once the company disclosed the abstract (creating a reasonable expectation/implication of positive data upon which a reasonable investor could base an investment decision), the failure to disclose such data could expose the company to potential 10b-5 claims IF SUCH FAILURE WERE DUE TO THE FACT THAT SUCH DATA WASN'T AS GOOD AS THE COMPANY HAD HOPED AND SUCH FACT/DATA WERE NOT DISCLOSED.
I seriously doubt the company or its lawyers would expose the company to such potential claims.