{"entity":{"id":"pet-adapted-her2-deescalation","kind":"pairing","name":"Early FDG-PET response → chemotherapy omission (HER2+)","aka":[],"tldr":"A PET scan after two cycles of antibodies alone identifies women who can be cured without chemotherapy.","summary":"This diagnostic-therapeutic pairing uses an early FDG PET scan to decide who can omit chemotherapy in HER2-positive breast cancer treated with dual HER2 blockade. After two cycles of trastuzumab and pertuzumab alone, with or without endocrine therapy, a metabolic response on PET predicts a pathological complete response to antibody-only treatment, and that complete response in turn predicts an excellent long-term outcome. In the randomised phase 2 PHERGain trial, PET responders continued the antibodies without chemotherapy and those reaching a pathological complete response skipped it altogether; the trial met its co-primary endpoints. The phase 3 PHERGain-2 trial and similar response-adapted designs such as WSG-ADAPT are now testing the approach more broadly.","asOf":"2026-09-07","links":[{"label":"ClinicalTrials.gov NCT03161353: PHERGain","url":"https://clinicaltrials.gov/study/NCT03161353"}],"tags":[],"related":[],"cancers":["breast-her2-positive"],"sections":[],"technologies":["fdg-pet"],"targets":[],"drugs":["trastuzumab","pertuzumab"],"companies":[],"institutions":[],"pathways":[],"terms":[],"trials":["phergain"],"people":[],"bottlenecks":[],"keyPapers":[],"journals":[],"dependsOn":[],"notes":[],"a":"fdg-pet","b":"dual-her2-blockade","rationale":"Metabolic response at 2 cycles predicts pCR to antibody-only therapy; pCR predicts excellent long-term outcome.","evidence":"Randomised phase 2 meeting co-primary endpoints; phase 3 pending.","pairingType":"diagnostic-therapeutic"},"route":"/pairings/pet-adapted-her2-deescalation/","neighbours":{"cancer":[{"id":"breast-her2-positive","kind":"cancer","name":"HER2-positive breast cancer","route":"/cancers/breast-her2-positive/"}],"technology":[{"id":"fdg-pet","kind":"technology","name":"FDG PET","route":"/technologies/fdg-pet/"}],"drug":[{"id":"pertuzumab","kind":"drug","name":"Pertuzumab","route":"/drugs/pertuzumab/"},{"id":"trastuzumab","kind":"drug","name":"Trastuzumab","route":"/drugs/trastuzumab/"}],"trial":[{"id":"phergain","kind":"trial","name":"PHERGain","route":"/trials/phergain/"}],"term":[{"id":"dual-her2-blockade","kind":"term","name":"Dual HER2 blockade","route":"/terms/dual-her2-blockade/"}]}}