Quest Diagnostics Inc. evidently found what it was looking for, as it agreed to acquire Haystack Oncology Inc. in an all-cash deal valued at up to $450 million with $300 million at closing and $150 million contingent on meeting specific milestones. Haystack focuses on minimal residual disease (MRD) testing, which can detect residual or recurring cancer in its early stages and help guide therapy decisions using blood samples rather than biopsied tissue. The companies expect the transaction to close before the end of June.