(UroToday.com) The third and final session of the Advanced Prostate Cancer Consensus Conference 2021 which was hosted virtually in the context of the COVID-19 pandemic focused on molecular characterization of both tissue and blood, with a focus on implications for treatment with PARP inhibitors and beyond. Following the conference presentations, Dr. Matthew Smith and Dr. Nicholas Mottet led a discussion of the consensus panel responses to questions relating to the role of tumor molecular testing.
First addressing question #87 in which there are insufficient genetic counselors, 80% of respondents suggested that it would be appropriate for physicians to order germline testing without pre-test counseling.
Next, Dr. Smith reviewed results of question #91 which showed that just over half (54%) of respondents would endorse the use of genetic counseling and germline testing for patients with intraductal/cribriform histology.
With respect to question #95 regarding the source of tissue for somatic genomic testing, there was a widespread of responses though 57% favored the use of the most recent archival tumor tissue with a new biopsy preferred by just over one-quarter of respondents (26%). Notably, only 3% of respondents preferred to use primary tumor archival tissue and 14% would prefer to use a circulating tumor DNA test.
Question #96, which addressed the question of tests to include in somatic genomic testing for patients with metastatic prostate cancer, provided a very mixed result without any clear preference or consensus from the group: 46% of panelists recommended comprehensive panel testing, 34% recommending BRCA1/2, mismatch repair evaluation, and additional DDR genes, and 20% recommending only BRCA1/2 and mismatch repair evaluation. Polling the audience, there was a similar lack of consensus.
Following a discussion of these results, Dr. Smith moved to question #101 which addresses the timing of PARP inhibitor treatment in patients with known BRCA1/2 aberrations. Here, the consensus panel was relatively closely split between those who recommended use after one line of androgen receptor pathway inhibitor (55%) and after one line of androgen receptor pathway inhibitor plus one line of chemotherapy (41%). The audience panel similarly was split between these two options.
Moving to question #103 which examined patients with known pathogenic BRCA1/2 mutations who are progressing on a PARP inhibitor after first-line androgen-pathway inhibitors, the majority of panel members (53%) preferred the use of docetaxel chemotherapy while a platinum-taxane chemotherapy combination was the second-most-popular choice (25%). The remaining treatment options were supported by a small number of respondents.
Dr. Smith then discussed question #105: among patients with pathogenic genomic ATM alterations, do you recommend treatment with a PARP inhibitor. Responses to this question were split with 33% of panelists saying yes, 29% saying yes if loss of protein function (by immunohistochemistry) or positive HRD score is noted; and 38% saying no. Notably, the audience response to this question had a large proportion of members abstaining.
Finally, Dr. Smith discussed the results of question #109 what assessed the role of platinum-based chemotherapy in patients with confirmed pathogenic aberrations in BRCA1/2 where there is no access to a PARP inhibitor. Here, 61% of respondents recommended use of platinum-based chemotherapy but only after at least one line of androgen receptor targeting agents and one line of taxane-based chemotherapy.
This concluded the discussion of the consensus panel responses in the context of the PARP inhibitors and beyond: Molecular characterization of tissue and blood session.Presented by: Matthew R. Smith, MD, Ph.D., Professor of Medicine, Harvard Medical School, Assistant in Medicine, Hematology/Oncology, Massachusetts General Hospital, Boston, Massachusetts, USA.
Nicolas Mottet, MD, PhD, Head of the Urology Department at Centre Hospitalier Universitaire de Saint-Étienne, and Professor of Surgery at Université Jean Monnet in Saint-Etienne, France
Written by: Christopher J.D. Wallis, University of Toronto, Twitter: @WallisCJD during the 2021 Advanced Prostate Cancer Consensus Conference, Saturday, October 9, 2021.