Most tumors lack a ‘viable’ precision treatment option
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Key takeaways:
- The proportion of tumors harboring a clinically actionable alteration matching an FDA-approved agent nearly doubled.
- First-in-class agents accounted for less than half of all approved precision therapies.
Precision oncology therapies requiring biomarker testing comprised 43% of all FDA oncology drug approvals between 1998 and 2022, study results published in Cancer Discovery showed.
This increase in available precision therapies occurred alongside a near doubling in the proportion of tumor samples that harbor actionable genetic alterations.
Despite these promising trends, the analysis revealed that most FDA-approved precision oncology therapies targeted only a handful of biomarkers, resulting in most patients being left without a biomarker-based precision therapy option to treat their cancer.
“While there was also an approximate fourfold increase in the number of tumors with a DNA-based biomarker that would make the patient eligible for treatment with a standard care targeted or immune-based therapy, there is still a considerable amount of work to be done in the precision oncology field,” Debyani Chakravarty, PhD, assistant attending molecular geneticist and lead scientist of the precision oncology knowledge base OncoKB at Memorial Sloan Kettering Cancer Center, told Healio.
“Our study shows that as of October 2022, almost two-thirds of patients still do not have viable precision oncology options for treatment, despite 43% of currently FDA-approved therapies being precision oncology therapies that require biomarker testing for patient selection,” she added. “Progress in this field will likely depend on developing targeted therapies that are effective in restoring physiologic functionality of common tumor suppressor genes or transcription factors that, to date, have not been amenable to the small molecular inhibitors.”
Background
Researchers chose 1998 as the starting point of their analysis because it marks the approval of one of the first molecularly targeted therapies — trastuzumab (Herceptin, Genentech) for HER2-positive breast cancer.
“There has been a continuing debate about the proportion of patients with cancer that benefit from precision oncology, partly due to conflicting views as to which molecular alterations are considered clinically actionable,” Chakravarty said. “To our knowledge, there has not been a systematic and quantitative analysis of how much the field of precision oncology has grown, the extent of true innovation in the field as represented by the number of first-in-class drugs, and the impact of this growth on the clinical actionability for a patient with cancer. Our group motivation for this research was to address those gaps.”
Methodology
Chakravarty and colleagues conducted a two-part study to evaluate the expansion of new precision oncology approvals and whether those approvals have led to an increase in the proportion of tumors eligible for treatment based on their targetable genetic alterations.
Researchers started by consulting multiple sources to compile a master list of all FDA oncology drug approvals between September 1998 and November 2022.
The list included approved agents that are effective in a “molecularly defined subset of patients” and required pretreatment molecular profiling, Chakravarty and colleagues wrote.
The second part of the study involved molecular profiling of 47,271 solid tumor samples analyzed by the MSK-IMPACT sequencing assay. Study investigators used 2017 and 2022 versions of the OncoKB precision oncology database to evaluate which samples harbored clinically actionable genetic alterations.
Key findings
Results showed 198 new oncology drugs approved by the FDA during the study period. Of these, approximately 43% comprised precision oncology drugs that require biomarker testing.
Less than half (47.8%) of all approved precision oncology therapies could be considered first-in-class, meaning they targeted a genomic alteration not yet recognized as clinically actionable.
The proportion of tumors harboring a clinically actionable alteration matching an FDA-approved standard care therapy increased from 8.9% to 31.6% between 2017 and 2022. Meanwhile, the number of tumors analyzed that did not harbor an actionable molecular target decreased by almost half, from 44.2% to 22.8%.
Investigators also observed a rapid increase in the number of precision oncology approvals between 2017 and 2022. A median of eight new agents per year received approval during that timeframe, compared with just one per year for the previous 20-year period.
Of the 29 approved follow-on agents that targeted previously known alterations, 20 (69%) used just one of seven biomarkers, including ERBB2 amplification, BCR-ABL1, BRAF V600E, ALK fusions/mutations, BRCA1/2 mutations and FGFR2 fusions.
The study’s main limitation included a lack of information about whether patients went on to receive the precision therapy they tested eligible for.
Clinical implications
The practical take-home for clinicians is that precision oncology treatments continue to expand their scope, both in terms of the number of new therapies and the types of tumors they effectively treat, according to Chakravarty. One example of this expansion is the fourfold increase in clinical actionability over the 5-year period between 2017 and 2022.
“However, we also know that — in clinical practice — precision oncology therapies are exceedingly expensive, and access to these drugs — while they may represent the optimal clinical option for a patient — may not be the final therapeutic [they] receive due to nonclinical practice-related issues,” she told Healio. “Thus, these trends represent the gaps that prevent the broader adoption of precision oncology in the community. I believe by quantifying the expansion of clinical actionability in a patient dataset, it gives us a tangible gauge to measure how far the needle to achieve equitable clinical practice for all patients — not just a selected few — needs to go.”
For more information:
Debyani Chakravarty, PhD, can be reached at Memorial Sloan Kettering Cancer Center, 323 E. 61st St., Room 615, New York, NY 10065; email: chakravd@mskcc.org.
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