Manufacturing of Pilot batch with non validated material

If we have any expert on Pilot Bio/QA Side, I have question for them. Is that acceptable to manufacture finished product and dose pilot scale bio batch with the drug substance from non-validated process. Our vendor wont be able to validate the process any time soon but they have manufactured all the batches as per cGMP. and we would like to make pilot bio batch for clinic.
if yo can also cite any reference guidance for this, it will be ideal