If for example, they find a partner with the Exosome test kits, they can sit on the negotiations for a really long time. There can be preliminary contracts signed and they don't need to report until the final contract is signed. Even then, they have 7 days to announce after the final contract. So, they can sign a contract contingent a material event - such as success of a test kit. Once the contingency is no longer present (ie. success of the test kit), the must report.
Generally it is a good idea to report when the certainty of the deal becomes apparent - even if the contract is not yet signed, because of the likelihood of a material event. PPHM would be within their rights to wait until the CC to announce any major developments as we are between the end of the quarter and the CC.
Mergers are similar, however there is obviously more to deal with, including the SEC.
This usually takes about a month if all goes well. So both companies can spend 6 months negotiating, then sign an agreement, file with the SEC, wait about a month, and then report the deal.
So from the above, the company would not want a shareholder to ask at a CC if they are involved in any final negotiations with a partner or if there are currently discussing merger possibilities. If that happened, they cannot lie, but they could respond that they have a policy to not discuss any current or future deals until a contract is signed. It would however, cause a stir no matter how they answered.