Trastuzumab-associated cardiac events in the Persephone trial.

Background: We report cardiac events in the Persephone trial which compares 6-12 months of adjuvant trastuzumab in women with confirmed HER2-positive, early-stage breast cancer.
Methods: Clinical cardiac events were defined as any of the following: symptoms and/or signs of congestive heart failure (CHF) and new or altered CHF medication. In addition, left ventricular ejection fraction (LVEF) was measured at baseline and then 3 monthly for 12 months.
Results: A total of 2500 patients, aged 22-82, were included: 1251 randomised to 12 months and 1249 to 6 months of trastuzumab treatment. A total of 93% (2335/2500) received anthracyclines, 49% of these (1136/2335) with taxanes. Cardiotoxicity delayed treatment in 6% of 12-month and 4% of 6-month patients (P=0.01), and stopped treatment early in 8% (96/1214) of 12-month and 4% (45/1216) of 6-month patients (P<0.0001). Between 7 and 12 months, more 12-month than 6-month patients had LVEFs<50% (8% vs 5%; P=0.004). LVEFs showed quadratic change over time, and 6-month patients had a more rapid recovery (P=0.02). In a landmark analysis twice as many 12-month patients, free of cardiac events at 6 months, had cardiac problems in months 7-12 (6% (66/1046) vs 3% (29/1035) of 6-month patients (P=0.0002)). Lower baseline LVEF predicted more cardiac dysfunction in both arms (reference ⩾65%: 55 to <65% OR 1.61 (95% CI 1.26-2.04); <55% OR 5.22 (3.42-7.95)) as did increasing age (reference <50: 50-59 OR 1.58 (1.17-2.12), 60-69 OR 1.91 (1.42-2.57)) 70+ OR 2.72 (1.82-4.08)) and prior use of cardiac medication (OR 8.46 (4.69-15.25)). >3 cycles of anthracycline was associated with higher risk of cardiac events only for 12-month patients (OR 1.41 (1.04-1.90)), and not for 6-month patients (OR 1.28 (0.91-1.79)).
Conclusions: We demonstrate significantly fewer cardiac events from 6 months of adjuvant trastuzumab compared with that from 12 months. This cardiac signal adds importance to the question of the optimum duration of adjuvant trastuzumab treatment. If 6 months is proven to have non-inferior outcomes to 12 months treatment, these data would support 6 months as the standard of care.
Competing Interests: HME reports grants from NIHR HTA during the conduct of the study. JD reports grants from NIHR HTA during the conduct of the study. SL reports grants from NIHR HTA during the conduct of the study. LH reports grants from NIHR HTA during the conduct of the study. AW reports personal fees from Roche, outside the submitted work. DC reports his institution was paid for consultancy work by DC from Roche, outside the submitted work. A-LV, EO, AH, IG, CP, DM, LH-D, KM and JH declare no conflicts of interest.