Curiosity project scientist John Grotzinger set off speculation about major news last week when he told National Public Radio that results would be "one for the history books."
"At this point in the mission, the instruments on the rover have not detected any definitive evidence of Martian organics," JPL said in its news release.
The news conference will be Monday in San Francisco, at the fall meeting of the American Geophysical Union.
Scientists are expected to share results from Curiosity's "full array of analytical instruments" during its investigation at a sandy patch of soil called Rocknest.
The rover spent about 40 days at Rocknest, conducting its first test with its Sample Analysis at Mars suite of instruments.
SAM, which has a mass spectrometer, laser spectrometer and gas chromatograph, can detect the presence of organics in gaseous forms, such as methane.
Curiosity is on a two-year mission in low-elevation Gale Crater, and scientists believe their best chance to find organics will be at Mt. Sharp, in the center of the crater.