Real-world data on outcomes using taxane, trastuzumab, and pertuzumab (THP) in patients with early stage HER2+ breast cancer.

Abstract

e12630 Background: In HER2+ early breast cancer, dual HER2 targeted combination of trastuzumab and pertuzumab with chemotherapy achieved higher rates of pathologic complete response (pCR) and improved long term outcomes. However, the optimal chemotherapy backbone is still under investigation. While neoadjuvant taxane in combination with trastuzumab and pertuzumab (THP) has been investigated in NEOSPHERE, patients received anthracycline-based regimen in the adjuvant setting. We report real-world data on long-term patient outcomes after neoadjuvant THP. Methods: An IRB-approved retrospective chart review at 2 academic centers was conducted using EMR to identify women with stage I-III HER2+ breast cancer who exclusively received neoadjuvant THP between 2013-2020. Clinicopathological characteristics and follow up information were extracted from surgical pathology and medical records. Results: 71 patients met criteria (median, 55 years). At presentation, 56 (79%) patients had stage II - III disease and 45 (63%) were lymph node negative. The majority of tumors were ER+ (43 patients, 61%) and received paclitaxel (46 patients, 65%) as their taxane backbone. pCR was achieved in 40 (56%) patients (Table); 38 (95%) continued with adjuvant HER2 therapy alone; 1 received adjuvant endocrine therapy only and 1 received no further treatment. Of the 31 (44%) patients without pCR, 9 received additional adjuvant chemotherapy in addition to HER2 directed therapy while 18 continued with HER2 therapy alone. During the follow-up period (median 34.7 mo, range 6.8-98.9 mo), 3 patients with lymph node positive disease on presentation had disease relapse. Two of the patients with pCR had local recurrence and one without pCR had distant metastasis (brain, lung). The 2 patients with local recurrence were successfully treated with salvage therapy and remain in remission. The patient with metastatic disease remains alive and on treatment. Conclusions: We showed that a real world HER2+ patient population treated with neoadjuvant THP achieved pCR rates consistent with what has been previously reported. In addition, with a median follow up of ̃ 3 years, only 3 patients had relapse supporting the utility of THP as potential de-escalation treatment in the neoadjuvant setting. Ongoing prospective trials, like NCT03716180, will further confirm the efficacy of this regimen in a prospective setting.[Table: see text]