Solna, Sweden, June 30, 2023. Affibody AB (“Affibody”) today announced that the first ten patients have been dosed in a Phase 2 clinical basket study of the PET imaging agent 68Ga-ABY-025 PET for non-invasive quantification of HER2-status in solid tumors.
 
The dosing of the tenth patient marks the end of the pilot study where participants with a previously biopsy-confirmed HER2-low metastatic breast cancer underwent a HER2-PET with 68Ga-ABY-025 followed by a new tumor biopsy guided by the results from the PET-images.
 
“We are excited about studying this important patient group with our unique Affibody® tracer” commented Fredrik Frejd, CSO of Affibody. “We are also impressed with the efficient and rapid patient recruitment catalyzed by our collaborators and the team behind the precision medicine initiative Theranostics Trial Center Karolinska (TTC-K).”
 
Preliminary results from the first ten patients indicate 68Ga-ABY-025 uptake in cancer lesions in all patients with HER2-low metastatic breast cancer. Interestingly, clear HER2-signals were noted in lesions from two patients with tumor biopsies that were HER2 0.
 
“The HER2-signal in metastatic lesions defined as completely HER2-negative (HER2 0) according to biopsy and immunohistochemistry suggest heterogeneity in HER2-expression within individual metastases” commented Rimma Axelsson, professor in nuclear medicine and principal investigator of the study. “These preliminary results demonstrate that molecular imaging can add information currently not available using conventional methods”.
 
All ten patients in the study had lesions with a value above SUV 6, used as cut-off for positive HER2 expression (1.), despite being defined as HER2 2+ ISH negative or lower, the classical definition for HER2 negative tumor lesions. Importantly, even patients with no detectable HER2 expression in standard ex vivo IHC assessment showed tracer uptake.
 
“This might imply that even patients with a HER2 0 tumor biopsy could benefit from treatment with HER2-targeted treatments when there is radiotracer uptake” commented Renske Altena, oncologist, deputy PI in the study and head of the Theranostics Trial Center Karolinska. “HER2 imaging information may change the way oncologists view HER2 low disease in the future” she continued.
 
References
(1.) Sörensen et al “Measuring HER2-Receptor Expression In Metastatic Breast Cancer Using [68Ga]ABY-025 Affibody PET/CT”. Theranostics. 2016 :262-71.
 
About the Phase 2 basket trial
The Phase 2 interventional clinical trial is planned to enroll 72 patients at the Karolinska University Hospital with the aim to evaluate the HER2-status in tumor lesions measured by Gallium-68-ABY-025-uptake on PET/CT with HER2-status defined by reference standard (laboratory analyses) in patients with gastroesophageal cancer (GEAC) and metastatic breast cancer with low HER2 expression (HER2-low mBC).
 
The participants in GEAC cohort of the study will undergo two sessions of HER2 PET and one 18-Fluorodeoxyglucose (18F-FDG) PET/CT for study purposes. The first HER2 PET is performed within 21 days before initiation of the systemic oncological treatment and is followed by tumor biopsies. A second HER2 PET and a second 18F-FDG PET will be performed adjacent to response evaluation after 3 courses of oncological therapy. Data from the PET investigations will be compared to HER2 expression analyses of the biopsy specimen and correlated to disease and survival data at follow-up one year after inclusion. Within the pilot study, participants with HER2-low mBC will undergo one HER2 PET followed by biopsies. The ClinicalTrials.gov Identifier is NCT05619016 and the EudraCT number is 2022-500448-39-00.