HER2 amplification (HER2+) is a therapeutic target for 2% (unselected)-6% (RAS wild-type) metastatic colorectal cancer (mCRC). In the HERACLES-A Trial of trastuzumab and lapatinib (Lancet Oncology, 2016), HER2+ KRAS wild-type mCRC patients achieved an overall objective response rate (CR+PR = ORR) of 30%. Based on this result and on preclinical trials, we activated HERACLES-B, evaluating a targeted chemotherapy precision approach by combining pertuzumab with T-DM1.
HERACLES-B is an open-label phase II trial in RAS/BRAF wild-type HER2+ mCRCs (as defined in Valtorta et al, 2015). ORR and Progression-Free Survival (PFS) are the primary and secondary end-points, respectively. With a Fleming/Hern design (H0=ORR 10%; α = 0.05; power=0.85), 7 OR/30 were required to demonstrate an ORR ≥30% (H1). Main inclusion criteria were: PS 0-1, progression after 5FU, oxaliplatin, irinotecan, and anti-EGFR containing regimens. Pertuzumab was dosed at 840 mg iv load, followed by 420 mg iv q3 weeks and T-DM1 at 3.6 mg/Kg q3 weeks. NGS-based molecular analyses of tumor tissue/plasma were performed.
From 8/2016 to 3/2018, 30 patients were enrolled, treated and evaluable for efficacy. Patients received a median of 3 prior regimens. Data lock and centralized radiological revision were completed by 30/7/2019. ORR was 10% [95% CI: 0-28] and stable disease (SD) 70% [95% CI: 50-85]. Median PFS was 4.8 mos. [95% CI: 3.6-5.8]. Higher HER2 IHC score (3+ vs 2+) was associated with objective response/SD ≥4 mos. [p = 0.03]. Drug-related G3 adverse events were observed only in 2 patients (thrombocytopenia); G ≤ 2 events in 84% of cycles (N = 296), mainly nausea and fatigue.
Although HERACLES-B did not reach its primary endpoint, disease control was achieved in 80% of patients with a median PFS of 4.8 mos. that is superimposable to the 4.2 mos. achieved in the positive HERACLES-A trial. While the ORR could have been weakened by the lower trastuzumab dose delivered with T-DM1, the retained favorable PFS might be due the combined ‘broad-brush’ effect of emtansine and the synergy with pertuzumab. Preliminary molecular results will be presented.
Clinical trial identification
Legal entity responsible for the study
Fondazione del Piemonte per l’Oncologia IRCC di Candiolo.
Fondazione Piemontese per l’Oncologia - FPO funded by Associazione Italiana per la Ricerca sul Cancro (AIRC). Roche provided pertuzumab and T-DM1 for free.
A. Sartore-Bianchi: Advisory / Consultancy: Amgen; Advisory / Consultancy: Bayer; Advisory / Consultancy: Sanofi. A. Amatu: Advisory / Consultancy: Roche; Advisory / Consultancy: Bayer; Advisory / Consultancy: Amgen. A. Ardizzoni: Advisory / Consultancy: Roche. L. Trusolino: Research grant / Funding (self): Symphogen; Research grant / Funding (self): Merus; Research grant / Funding (self): Servier; Research grant / Funding (self): Pfizer; Speaker Bureau / Expert testimony: Eli Lilly; Speaker Bureau / Expert testimony: AstraZeneca; Speaker Bureau / Expert testimony: Merck KGaA. S. Siena: Advisory / Consultancy: Amgen; Advisory / Consultancy: Bayer; Advisory / Consultancy: BMS; Advisory / Consultancy: CheckMab; Advisory / Consultancy: Celgene; Advisory / Consultancy: Clovis; Advisory / Consultancy: Daiichi Sankyo; Advisory / Consultancy: Incyte; Advisory / Consultancy: Merck; Advisory / Consultancy: Novartis; Advisory / Consultancy: Roche-Genentec; Advisory / Consultancy: Seattle Genetics. All other authors have declared no conflicts of interest.
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