The feasibility study is the first step in process development.   During the feasibility study, different synthetic strategies and variables can be investigated, for instance,  key intermediate fragments, optimum combination of protecting groups, choice of the most efficient activation, definition of the most suitable counterions, selection of the most effective solvents, …

In most cases, the feasibility studies are relatively short for developments in SPPS.   Therefore, a small sample of non-GMP peptide, up to a few grams, can be made available in just a few weeks.     

Process development in liquid phase synthesis is more time-consuming, as each and every fragment has to be optimized for the synthesis, isolation and characterization.   Depending on the complexity and length of the peptide sequence, a feasibility study in liquid phase can take up to a few months before a first sample of a few grams is finally obtained and purified. 

The outcome of a feasibility study includes :

• the availability of a synthetic process for the production of cGMP grade quantities
• all the necessary data required for the scale up studies in kilolabs
• the initial data necessary to select and set-up a large scale purification method
• the information required to narrow the specifications on the final peptide and on the intermediates
• the analytical methods necessary to characterize the final peptide and intermediates 

The completion of the feasibility study is also an important concrete milestone to allow a more accurate evaluation of the whole economics of the selected synthetic method.