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Clinical Trial
. 2021 Feb:144:151-161.
doi: 10.1016/j.ejca.2020.11.008. Epub 2020 Dec 18.

Serial [18F]-FDHT-PET to predict bicalutamide efficacy in patients with androgen receptor positive metastatic breast cancer

Jorianne Boers  1 , Clasina M Venema  1 , Erik F J de Vries  2 , Geke A P Hospers  1 , Hendrikus H Boersma  3 , Bart Rikhof  4 , Christine Dorbritz  5 , Andor W J M Glaudemans  2 , Carolina P Schröder  6
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Free article
Clinical Trial

Serial [18F]-FDHT-PET to predict bicalutamide efficacy in patients with androgen receptor positive metastatic breast cancer

Jorianne Boers et al. Eur J Cancer. 2021 Feb.
Free article

Abstract

Background: The androgen receptor (AR) is a potential target in metastatic breast cancer (MBC), and 16β-[18F]-fluoro-5α-dihydrotestosterone positron emission tomography ([18F]-FDHT-PET) can be used for noninvasive visualisation of AR. [18F]-FDHT uptake reduction during AR-targeting therapy reflects AR occupancy and might be predictive for treatment response. We assessed the feasibility of [18F]-FDHT-PET to detect changes in AR availability during bicalutamide treatment and correlated these changes with treatment response.

Patients and methods: Patients with AR + MBC, regardless of oestrogen receptor status, received an [18F]-FDHT-PET at baseline and after 4-6 weeks bicalutamide treatment. Baseline [18F]-FDHT uptake was expressed as maximum standardised uptake value. Percentage change in tracer uptake, corrected for background activity (SUVcor), between baseline and follow-up PET scan (% reduction), was assessed per-patient and lesion. Clinical benefit was determined in accordance with Response Evaluation Criteria in Solid Tumours (RECIST) 1.1 or clinical evaluation (absence of disease progression for ≥24 weeks).

Results: Baseline [18F]-FDHT-PET in 21 patients detected 341 of 515 lesions found with standard imaging and 21 new lesions. Follow-up [18F]-FDHT-PET was evaluable in 17 patients with 349 lesions, showing a decrease in median SUVcor from 1.3 to 0.7 per-patient and lesion (P < 0.001). Median % reduction per-patient was -45% and per-lesion -39%. In patients with progressive disease (n = 11), median % reduction was -30% versus -53% for patients who showed clinical benefit (in accordance with RECIST (n = 3) or clinical evaluation (n = 3); P = 0.338).

Conclusion: In this feasibility study, a bicalutamide-induced reduction in [18F]-FDHT uptake could be detected by follow-up [18F]-FDHT-PET in patients with AR + MBC. However, this change could not predict bicalutamide response.

Clinical trial information: NCT02697032.

Keywords: Androgen receptor; Bicalutamide; Metastatic breast cancer; [(18)F]-FDHT-PET.

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Conflict of interest statement

Conflict of interest statement J.B., C.M.V., H.H.B., B.R., C.D., and A.W.J.M.G. declare no conflict of interest. E.F.J.d.V. reports receiving research funding through grants from ZonMw, the Dutch Cancer Foundation (KWF), MS Research Foundation, and has assisted in conducting contracted research studies funded by Rodin Therapeutics, Lysosomal Ltd, Hoffmann-La Roche, and Ionis Pharmaceuticals. G.A.P.H. reports receiving research funding from The Seerave Foundation and Bristol-Myers Squibb (paid to the institution UMCG) and has served in a consulting/advisory role for Bristol-Myers Squibb, MSD, Novartis, Pfizer, Pierre Fabre, Amgen, and Roche (paid to the institution UMCG). C.P.S. reports receiving research funding from Pfizer, Roche, Genentech, SNS Oncology, G1 Therapeutics, Abbvie, Synthon, and CytoMx Therapeutics (paid to the institution UMCG).

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