Aim:
Pertuzumab is a humanised monoclonal antibody preventing the dimerisation of HER2. Its addition to trastuzumab and taxane has demonstrated improved outcomes in patients with metastatic HER2 positive breast cancer. Hypersensitivity reactions to pertuzumab have been documented in case reports with successful desensitisation.1 These desensitisation protocols are time and labour intensive, perpetual and can negatively impact on quality of life. We describe case reports of two patients treated using the King protocol followed by a graduated return to normal dosing over six cycles.
Methods:
Two female patients, aged 60 and 70-years-old presented with HER2 amplified de novo metastatic breast cancer. Both were commenced on paclitaxel, pertuzumab and trastuzumab and treated as per protocol. During cycle 4, 18 minutes and 10 minutes into pertuzumab infusion respectively, both patients experienced facial flushing, dyspnoea, rigors and hypotension. Given the clinical benefit of continuing pertuzumab, following literature search, the decision was made to re-challenge both patients using desensitisation.
Results:
Both patients were pre-medicated with corticosteroids and antihistamines and initiated on the published desensitisation protocol. Desensitisation was well tolerated with no further reaction during subsequent infusions. On cycles 2-4 of desensitisation, the 2 bag protocol was continued and the initial rate was progressively increased. Patient 2 is due for cycle 5 at the time of writing. Patient 1 completed cycle 5-6 desensitisation, with pre-medication and a 1 bag infusion. Cycle 7 was given as a straight 60 minute infusion without hypersensitivity, and she completed a further 5 cycles at normal rate without complication.
Conclusion:
For patients who experience hypersensitivity reactions to pertuzumab, a desensitisation protocol should be considered to enable the safe and continued use of optimal agents. If initial desensitisation is well tolerated, graduated step down to normal infusion rates can be considered.