Multiple alterations and resistance
The complex genetics of cancers has led researchers to explore combinations of targeted and other therapies to address multiple defects at the same time.
“Not surprisingly, the most common collision of multiple genetic alterations within the same tumor was in the commonly altered tumor suppressor genes: TP53, APC, and PTEN,” Dr. Flaherty said.
“An increasing body of evidence supports a role for loss-of-function alterations in these genes to confer resistance to many targeted therapies,” he added. “While we don’t have targeted therapies yet established to directly counter this form of therapeutic resistance, we hypothesize that various types of combination therapy may be able to indirectly undercut resistance and enhance the benefit of many targeted therapies.”
The NCI-MATCH researchers will continue to mine this large dataset to better understand the many small, genetically defined cancer subpopulations.
“We will continue to report the outcome of the individual treatment subprotocols, and combining this genetic analysis with those outcomes will likely inform the next clinical trials,” Dr. Flaherty said.
Actionable mutations make a difference
Precision oncology experts agree that NCI-MATCH results are impressive and add a fuller appreciation that actionable mutations make a clinical difference.
“This is a powerful, extremely well-designed study, a tour de force of collaborative science,” said Stephen Gruber, MD, PhD, director of the Center for Precision Medicine at City of Hope National Medical Center in Duarte, Calif.
“The future holds even more promise,” he added. “Our ability to interrogate the genomic landscape of cancer is improving rapidly. Tumor testing helps get the right drug to the right tumor faster than a guidelines-based approach from historical data of combination chemotherapy. This is a likely game changer for the way oncologists will practice in the future, especially as we learn more results of subset trials. The NCI-MATCH researchers have taken a laser-focused look at the current data, but we now know we can look far more comprehensively at genomic profiles of tumors.”
From the viewpoint of the practicing oncologist, co-occurring resistance mutations make a difference in defining what combinations are likely and, more importantly, less likely to be effective. “When we see two mutations and one is likely to confer resistance, we can make a choice to avoid a drug that is not likely to work,” Dr. Gruber said.
“The NCI-MATCH trial allows both approved and investigational agents, which expands the possibility of matching patients to newer agents. This is especially relevant if there are no FDA-approved drugs yet for some molecular aberrations,” said Lillian L. Siu, MD, a senior medical oncologist at the Princess Margaret Cancer Centre in Toronto. “This trial enables such evaluations under the auspice of a clinical trial to provide important knowledge.”
Both experts agree that in-depth biological interrogations of cancer will move the field of precision oncology forward. Dr. Gruber said that “studies have not yet fully addressed the power of germline genetic testing of DNA. Inherited susceptibility will drive therapeutic choices – for example, PARP inhibitors that access homologous recombination deficiency for breast, ovarian, and prostate cancer. We will learn more about treatment choices for those cancers.”
Dr. Siu added: “I truly believe that liquid biopsies [circulating tumor DNA] will help us perform target-drug matching in a less invasive way. We need to explore beyond the genome to look at the transcriptome, proteome, epigenome, and immunome, among others. It is likely that multiomic predictors are going to be able to identify more therapeutic options compared to single genomic predictors.”
Dr. Flaherty noted that all tumor samples from patients assigned to treatment are being subjected to whole-exome sequencing to further the discovery of the genetic features of responsive and nonresponsive tumors.
NCI-MATCH was funded by the National Cancer Institute. Dr. Flaherty disclosed relationships with Clovis Oncology, Loxo, X4 Pharma, and many other companies. His coauthors disclosed many conflicts as well. Dr. Gruber is cofounder of Brogent International. Dr. Siu disclosed relationships with Agios, Treadwell Therapeutics, Merck, Pfizer, and many other companies.
SOURCE: Flaherty KT et al. J Clin Oncol. 2020 Oct 13. doi: 10.1200/JCO.19.03010.