The matter of how adhesion of its Viaskin Peanut allergy patch relates to efficacy became a major problem for DBV Technologies SA, which drew a complete response letter (CRL) for the once-daily epicutaneous (EPIT) product. Shares of the Montrouge, France-based firm (NASDAQ:DBVT) closed Aug. 4 at $2.34, down $1.76, or 43%, in reaction to the CRL for the patch, designed to protect children ages 4 to 11. The FDA wants DBV to modify the patch, which means a new human-factor study; officials also are requiring clinical data for the modified patch.