In the field of biotechnology, obviousness is considered at hand not only when results are clearly predictable, but also when there is a reasonable expectation of success. In order to render a solution obvious, it is sufficient to establish that the skilled person would have followed the teaching of the prior art with a reasonable expectation of success. Likewise, a mere "try and see" attitude in light of the closest prior art does not necessarily render the solution inventive.
On the other hand, a "reasonable expectation of success" is not to be confused with the "hope to succeed". If researchers are aware when embarking on their research that, in order to reach a technical solution, they will need not only technical skill but also the ability to make the right non-trivial decisions along the way, this cannot be regarded as a "reasonable expectation of success".
For the assessment of inventive step of antibodies, see G-II, 5.6.2.