(Updates share price)

CHARLOTTE, N.C. ( TheStreet) --An update on my previously discussed long trade idea for Chelsea Therapeutics ( CHTP):

Last night, the company said it plans to meet with U.S. drug regulators seeking permission to change the primary endpoint of an ongoing phase III study of the droxidopa in patients with orthostatic hypotension.

As a result, data from this study won't be ready for release this quarter, but will be delayed into early next year, pending the outcome of the FDA meeting, the company said.

Chelsea executives explained last night that altering the ongoing phase III study to use a different primary endpoint may increase the chances for a successful outcome. Recall, the first phase III study failed -- a negative result tossed up to bad trial design since droxidopa did show some clinical benefit to patients.

That strategy may work, but the maneuver also significantly changes the Chelsea-droxidopa story and raises the level of risk. Instances are rare in which a company makes a radical change to a pivotal study midstream. It's not even clear if the FDA will allow the change to be made.

With Chelsea beaten up in late September on the failure of the first droxidopa trial, the risk-reward going into the second trial was much improved. To me, this made Chelsea a reasonable long trade going into the results of the second phase III study, which were due later this quarter.

The risk-reward is no longer as favorable, unfortunately, because the design of the second phase III study is now uncertain. Chelsea may get what it wants -- a new primary endpoint and a positive outcome for droxidopa. If so, the stock will definitely be higher. My worry is that the risk of the opposite happening is now a lot higher, so for me, this long trade idea no longer works.

I posted my idea for a long trade in Chelsea on Oct. 1 with the stock around $3. Chelsea shares were down 12.6% to $2.57 in Tuesday trading.

-- Reported by Adam Feuerstein in Boston

Adam Feuerstein writes regularly for TheStreet.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.