Due to the lack of literature on the effects of trastuzumab in pregnancy, an interest has been taken in a patient that incidentally became pregnant while on adjuvant treatment in the first trimester following diagnosis of locally advanced breast cancer.

Introduction: Liposomes are nanospheres of lipid bilayer which can bind drug either in the phospholipid membrane or in the central aqueous droplet. Liposomes loaded with a drug can facilitate drug delivery, and empty liposomes can sequester certain drugs to reduce aqueous drug concentrations in experimental intoxication. Therapeutic dialysis in intoxication is limited by drug volumes of distribution and blood protein binding. In rats intoxicated with intravenous amitriptyline, we examined adding intravenous membrane-binding 1,2-dioleoyl-sn-glycero-3phosphoglycerol (DOPG) liposomes to liposome supported peritoneal dialysis (LSPD) in which liposomes in dialysate were augmented with an acidic core. The hypothesis was that a "gradient of liposome affinity" would increase LSPD amitriptyline concentrations. Methods: Seven control and five intravenous DOPG liposome pre-treated rats were injected with amitriptyline, followed 10 min later by a 10-min LSPD dwell. Results: DOPG liposomes increased blood amitriptyline concentrations by 50%; control (median [IQR] 1250 [951-1356] nmol/L; intravenous DOPG 1702 [1602-1864] nmol/L, p ¼ 0.032). However, there was no corresponding increase in LSPD dialysate amitriptyline concentrations at the end of the dwell; control (median [IQR] 430 [334-2180] nmol/l, intravenous DOPG 414 [387-483] nmol/L p ¼ 0.75). Conclusions: Pre-treatment with DOPG liposomes decreased amitriptyline volume of distribution but had no significant effect on elimination of amitriptyline by LSPD.

The available literature on the effects of trastuzumab on pregnancy in the first trimester is limited. Case reports discuss the presence of oligohydramnios on fetal USS that result in a living baby that seemingly lacks any abnormalities. There may also be a link with higher rates of spontaneous abortion. We describe a young 32 year old on trastuzumab for a locally invasive HER2-positive breast cancer who became pregnant with fetal exposure to the treatment. After cessation of trastuzumab at 28 weeks, she delivered a healthy baby girl at 37 weeks gestation who, at 7 years of age now, still does not display any evidence of negative effects of trastuzumab exposure.