For determining therapeutic actionability, the strict criteria were used; 593 patients (4.95%) with recurrent or metastatic disease were identified. For these patients, consideration of a targeted therapy, either as part of standard care or as part of an investigation or research protocol, was important.
Of this group, 44% received therapy targeting the germline alteration. Regarding specific genes, 50% of BRCA1/2 carriers and 58% of Lynch syndrome patients received targeted treatment. With respect to tier 2 genes, 40% of patients with PALB2, 19% with ATM, and 37% with RAD51C or 51D received a poly (ADP-ribose) polymerase (PARP) inhibitor.
Among patients with a BRCA1/2 mutation who received a PARP inhibitor, 55.1% had breast or ovarian cancer, and 44.8% had other tumor types, including pancreas, prostate, bile duct, gastric cancers. These patients received the drug in a research setting.
For patients with PALB2 alterations who received PARP inhibitors, 53.3% had breast or pancreas cancer, and 46.7% had cancer of the prostate, ovary, or an unknown primary.
The discussant for the paper, Funda Meric-Bernstam, MD, chair of the Department of Investigational Cancer Therapeutics at the University of Texas MD Anderson Cancer Center, Houston, pointed out that most of the BRCA-positive patients had cancers traditionally associated with the mutation. “There were no patients with PTEN mutations treated, and interestingly, no patients with NF1 were treated,” she said. “But actionability is evolving, as the MEK inhibitor selumitinib was recently approved for NF1.”
Some questions remain unanswered, she noted, such as: “What percentage of patients undergoing tumor-normal testing signed a germline protocol?” and “Does the population introduce a bias – such as younger patients, family history, and so on?”
It is also unknown what percentage of germline alterations were known in comparison with those identified through tumor/normal testing. Also of importance is the fact that in this study, the results of germline testing were delivered in an academic setting, she emphasized. “What if they were delivered elsewhere? What would be the impact of identifying these alterations in an environment with less access to trials?
“But to be fair, it is not easy to seek the germline mutations,” Dr. Meric-Bernstam continued. “These studies were done under institutional review board protocols, and it is important to note that most profiling is done as standard of care without consenting and soliciting patient preference on the return of germline results.”
An infrastructure is needed to return/counsel/offer cascade testing, and “analyses need to be facilitated to ensure that findings can be acted upon in a timely fashion,” she added.
The study was supported by MSKCC internal funding. Dr. Stadler reported relationships (institutional) with Adverum, Alimera Sciences, Allergan, Biomarin, Fortress Biotech, Genentech/Roche, Novartis, Optos, Regeneron, Regenxbio, and Spark Therapeutics. Dr. Meric-Bernstram reported relationships with numerous pharmaceutical companies.
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