Abstract 4058
Background
For individual treatment planning in patients with metastatic castration resistant prostate cancer (mCRPC), molecular analyses are increasingly used. As most patients have bone only disease, bone biopsies are often the only source for tumour tissue. However, the success rate of computed tomography (CT)-guided bone biopsies for molecular analyses in mCRPC patients is only 36.5-44%. Positron emission tomography (PET) using 68Ga-PSMA is a promising tool to increase the success rate of bone biopsies for molecular analyses in mCRPC patients.
Methods
In this multicenter study, the success rate of 68Ga-PSMA guided bone biopsies for molecular diagnostics was retrospectively evaluated in a subset of mCRPC patients who underwent a bone biopsy for whole-genome DNA sequencing within the CPCT-02 study (NCT01855477). To evaluate whether biopsies were obtained from a 68Ga-PSMA positive lesion, rigid body image registration of 68Ga-PSMA PET/CT and interventional CT was performed. This technique provided volume of interest (VOI) based quantification of 68Ga-PSMA uptake at the exact biopsy site. In addition, the potential impact of molecular analyses on clinical decision making was evaluated.
Results
Sixty-nine 68Ga-PSMA-guided biopsies were eligible for primary analysis. Based on tumor percentage ≥ 30%, 70% of 68Ga-PSMA-guided biopsies was eligible for molecular analyses. At biopsy sites with positive, inconclusive or negative 68Ga-PSMA uptake, tumour percentage was ≥ 30% in 73%, 55% and 36% of the biopsies, respectively (p = 0.0850). At sites of biopsies with a tumour percentage ≥ 30%, standardized uptake value (SUV)max and SUVmean of 68Ga-PSMA were significantly higher (p = 0.0260 and p = 0.0129 respectively), whereas Hounsfield units (HU)mean and HUmax on CT were significantly lower (p = 0.0189 and p = 0.0494 respectively). Molecular analyses identified potentially targetable aberrations including PTEN loss, AR amplifications, and BRCA variants.
Conclusions
68Ga-PSMA PET/CT is a useful technique to improve the success rate of CT-guided bone biopsies for molecular analyses in mCRPC patients. Successful bone biopsies for molecular analyses can improve individual treatment planning by detecting targetable mutations.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
R. de Wit: Advisory / Consultancy, Speaker Bureau / Expert testimony, Research grant / Funding (institution): Sanofi; Advisory / Consultancy, Speaker Bureau / Expert testimony: Merck; Advisory / Consultancy, Research grant / Funding (institution): Bayer; Advisory / Consultancy: Roche; Advisory / Consultancy: Janssen; Advisory / Consultancy: Clovis. N. Mehra: Advisory / Consultancy, Research grant / Funding (institution): Astellas; Advisory / Consultancy, Research grant / Funding (institution): Janssen; Research grant / Funding (institution): Pfizer; Advisory / Consultancy, Research grant / Funding (institution): Roche; Advisory / Consultancy, Research grant / Funding (institution): Sanofi Genzyme; Advisory / Consultancy: MSD; Advisory / Consultancy: BMS; Advisory / Consultancy: Bayer. A.A.M. Van der Veldt: Honoraria (institution), Advisory / Consultancy: BMS; Honoraria (institution), Advisory / Consultancy: MSD; Honoraria (institution), Advisory / Consultancy: Roche; Honoraria (institution), Advisory / Consultancy: Novartis; Honoraria (institution), Advisory / Consultancy: Pierre Fabre; Honoraria (institution), Advisory / Consultancy: Pfizer; Honoraria (institution), Advisory / Consultancy: Sanofi; Honoraria (institution), Advisory / Consultancy: Ipsen. M.P. Lolkema: Research grant / Funding (institution): JNJ; Research grant / Funding (institution): Astellas. All other authors have declared no conflicts of interest.
Resources from the same session
4543 - Long-term real-world (RW) outcomes in patients with advanced melanoma (MEL) treated with ipilimumab (IPI) and non-IPI therapies: IMAGE study
Presenter: Stéphane Dalle
Session: Poster Display session 3
Resources:
Abstract
4523 - Prognostic Factors for efficacy of Ipilimumab used after AntiPD1 and/or BRAF+MEK inhibitors in Melanoma Patients: an Italian Melanoma Intergroup study
Presenter: Riccardo Marconcini
Session: Poster Display session 3
Resources:
Abstract
3632 - Rechallenge with combination ipilimumab and anti-PD-1 (IPI+PD1) in metastatic melanoma after acquired resistance to IPI+PD1 immunotherapy
Presenter: Adriana Hepner
Session: Poster Display session 3
Resources:
Abstract
3732 - Clinicopathologic characteristics of immune colitis in melanoma patients treated with combination ipilimumab and anti-PD1 (IPI+PD1) and PD1 monotherapy.
Presenter: Kazi Nahar
Session: Poster Display session 3
Resources:
Abstract
5005 - Real-world outcomes of ipilimumab plus nivolumab for advanced melanoma in the Netherlands
Presenter: Michiel van Zeijl
Session: Poster Display session 3
Resources:
Abstract
5524 - Utilization of Real-World Data to Assess the Effectiveness of Immune Checkpoint Inhibitors (ICIs) in Elderly Patients with Metastatic Melanoma
Presenter: D Scott Ernst
Session: Poster Display session 3
Resources:
Abstract
5884 - Tumor mutational burden and response to PD-1 inhibitors: an analysis of 89 cases of metastatic melanoma.
Presenter: Léa Dousset
Session: Poster Display session 3
Resources:
Abstract
3120 - Increase in S100B and LDH as early outcome predictors for non-responsiveness to anti-PD-1 monotherapy in advanced melanoma.
Presenter: Elisa Rozeman
Session: Poster Display session 3
Resources:
Abstract
2157 - Immune status defined by molecular information layers predicts response to pembrolizumab treatment in advanced melanoma
Presenter: Guillermo Prado-Vázquez
Session: Poster Display session 3
Resources:
Abstract
2553 - Interim analysis of a phase Ib study of cobimetinib plus atezolizumab in patients with advanced BRAFV600 wild type melanoma progressing on prior anti-PD-L1 therapy
Presenter: Shahneen Sandhu
Session: Poster Display session 3
Resources:
Abstract