Either a DLP appliance or write DLP logic into the application to look for and validate the types of at-risk data one wishes to prevent leaking and decide how to handle/quarantine/sanitize/hold/reject it. There are pros and cons to each direction.

If this were for the financial sector I personally would lean towards an appliance for audit and checkbox reasons. Talk to your auditors and compliance team, get their requirements and if those requirements come with a price tag, make them meet with the person in your org that has the purchasing authority to sort that out. The price should include some professional service time from the vendor to assist integrating their appliance with your code in a manor that does not violate your customer SLA.