Pilot study of ⁶⁸Ga-DOTA-F(ab')2-trastuzumab in patients with breast cancer

OBJECTIVE: Ga-1,4,7,10-Tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (DOTA)-F(ab')2-trastuzumab [Ga-DOTA-F(ab')2-trastuzumab] has been developed at our institution as a positron imaging reagent for assessing human epidermal growth factor receptor 2 (HER2) expression status by in-vivo imaging. Initial studies on animals demonstrated promising results in the monitoring of treatment response to heat shock protein 90-targeted drugs that inhibit the client protein HER2. We report here our initial clinical experience in the assessment of the toxicity, pharmacokinetics, biodistribution, and dosimetry profile of Ga-DOTA-F(ab')2-trastuzumab with PET/computed tomography using a mean of 236 MBq/5 mg administered intravenously. MATERIALS AND METHODS: A group of 16 women with breast cancer were enrolled in this study. The one patient who did not receive Ga-DOTA-F(ab')2-trastuzumab was excluded from analysis. Both HER2-negative (n=7) and HER2-positive (n=8) cases were studied. Among the latter, seven had undergone trastuzumab treatment previously and one had not. RESULTS: It was determined that Ga-DOTA-F(ab')2-trastuzumab was well tolerated, with a T of ∼3.6±0.9 h; the critical organ was the kidney, with a mean dose of 0.383 cGy/37 MBq; and tumor targeting was seen in 4/8 patients with HER2-positive disease. CONCLUSION: The reagent is safe, and assessments through additional studies in a better-defined group of patients, using larger administered masses of antibodies, with a better immunoreactive fraction are needed.