CHICAGO — An “adaptive response” treatment strategy identified a subset of patients with HER2-positive early breast cancer who benefited from a chemotherapy-free treatment plan, according to the phase II PHERGain trial.
The strategy is based on evaluating an early response to a dual HER2 blockade with trastuzumab (Herceptin) and pertuzumab (Perjeta) with 18F-FDG PET imaging and postsurgical pathological complete response (pCR). Among 267 patients in an intention-to-treat [ITT] population, 220 (79.6%) had an early response (based on PET imaging) to 2 cycles of treatment with trastuzumab and pertuzumab, while 86 (37.7%) went on to have a pCR after 6 more cycles of chemotherapy-free treatment, reported Javier Cortés, MD, PhD, of the Ramón y Cajal University Hospital, in Madrid.
Among these 86 patients, only one had an invasive event (locoregional ipsilateral recurrence) for a 3-year invasive disease-free survival (iDFS) rate of 98.8% (95% CI 96.3-100.0), he said in a presentation at the American Society of Clinical Oncology (ASCO) annual meeting. The current findings met one of the trial’s two primary endpoints, previously reported in 2021 in The Lancet.
“This strategy might identify 30% of patients who may be cured without the need for chemotherapy, and only treated with a combination of trastuzumab and pertuzumab and endocrine therapy, if appropriate,” Cortés said.
Regarding the entire ITT population, which included patients who received some chemotherapy, the 3-year iDFS rate was 95.4% (95% CI 92.8-98.0), thus meeting the study’s second primary endpoint with ≤15 patients experiencing an iDFS event (P
More