A subcutaneous injectable form of trastuzumab achieved pharmacokinetic and clinical outcomes that equaled those of intravenous infusion for women with HER2-positive breast cancers in a randomized open-label phase III study.
The international HannaH trial found no significant differences in presurgical serum trough levels at any time during the six-cycle neoadjuvant treatment. At the end of the year-long study, 45% of the subcutaneous group and 41% of the intravenous group had a pathological complete response (pCR).
The subcutaneous form of trastuzumab (Herceptin) takes 5 minutes to administer; patients can self-administer the drug at home. The infusion takes 90 minutes and must be done in the clinic.
If clinical results are equivalent, the injection could become an attractive alternative to intravenous treatment, Dr. Gustavo Ismael of the Hospital Amaral Carvalho, Jaú, Brazil, and his coauthors proposed in the Aug. 9 online issue of the Lancet Oncology (2012 [doi.org/10.1016/S1470-2045(12)70329-7]).*
"The shortened duration of administration with subcutaneous trastuzumab ... suggests the potential for substantial time saving for patients, physicians, and nursing staff," the investigators wrote.
Susan Willson, a spokesperson for Genentech, said the company is looking at the HannaH data, as well as that of other studies, to determine whether the subcutaneous form of trastuzumab will be put forth to the Food and Drug Administration.
Earlier this year, Roche, Genetech’s parent company, submitted a line extension application for subcutaneous trastuzumab to the European Medicines Association. The requested indication is the treatment of HER-2-positive breast cancer.
Trastuzumab Given with Neoadjuvant Chemo
The HannaH (enHANced treatment with NeoAdjuvant Herceptin) trial randomized 596 women with HER-2 positive breast cancer to six cycles of neoadjuvant chemotherapy with either the injections or intravenous infusions; both were administered once every 3 weeks.
The injection was a fixed dose of 600 mg trastuzumab with recombinant hyaluronidase PH-20 delivered to the thigh by study nurses. The enzyme temporarily degrades interstitial hyaluronan, expanding the space to accommodate the volume of the injection.
Women in the subcutaneous group did not take a loading dose of the medication. Those in the intravenous group received an 8 mg/kg loading dose followed by a 6 mg/kg maintenance dose. The follow-up period was 24 months or until disease recurrence
The chemotherapy regimen for both groups consisted of four 3-week cycles of docetaxel (Taxotere) followed by four cycles of fluorouracil and cyclophosphamide. After surgery, all patients continued their trastuzumab regimen for 1 year.
Median patient age was 50 years. About 50% were positive for estrogen receptor tumors. More than half had operable cancer; more than a third had locally advanced cancer; and about 6% had inflammatory breast cancer. Median follow-up in both groups was a little more than 1 year.
The pharmacokinetic profile was similar between the two forms of trastuzumab. After the first cycle, the mean trough serum level was similar between the injectable and intravenous forms (32.7 mcg/mL vs. 34.5 mcg/mL). The levels were also similar before the third cycle (45 and 48 mcg/mL). Almost all patients (98%) reached the therapeutic level of more than 20 micrograms/ml by cycle 8.
The mean presurgical trough level of the subcutaneous form was 58 mcg/mL; for the intravenous form, the mean level was 79 mcg/mL.
Similar Efficacy and Toxicity
The efficacy analysis included 523 patients and showed noninferiority of subcutaneous trastuzumab to intravenous trastuzumab. A pathological complete response occurred in 45% of the subcutaneous group and in 41% of the intravenous group in a per-protocol analysis. An intent-to-treat analysis showed similar numbers, with a complete pathological response in 42% of the subcutaneous group an 37% of the intravenous group.
Overall responses rates, including complete and partial responses, were comparable. Event-free and overall survival data were not yet mature, and have yet to be reported.
The rate of adverse events was similar between the subcutaneous and intravenous groups: alopecia (63% each), nausea (49% each), neutropenia (44% subcutaneous vs. 46% intravenous), diarrhea (34% subcutaneous vs. 37% intravenous), asthenia (25% each), and fatigue (23% subcutaneous vs. 26% intravenous).
The same proportion of patients in each group experienced at least one serious adverse event (52%). The most common were neutropenia, leucopenia, and febrile neutropenia.
Four adverse events lead to death – one in the subcutaneous group and three in the intravenous group during neoadjuvant treatment. These included a fatal acute pneumonia in an obese 66-year-old with pulmonary fibrosis in the subcutaneous group. In the intravenous group, the deaths were a myocardial infarction in an obese patient with a history of hypertension; a sudden death in an overweight patient who with hypertension and diabetes; fatal septic shock in a patient who developed febrile neutropenia. The septic shock and cardiac deaths were attributed to the treatment, the investigators said.