FDA Updates: Assays Used in Cancer Care Get Green Light

August 9, 2020

Adaptive Biotechnologies’ clonoSEQ gets third approval; FDA also acts on first at-home treatment for spinal muscular atrophy.

This report has been updated to reflect a revised FDA press release issued to clarify the Guardant360 CDx approval.

clonoSEQ for MRD in CLL. On Thursday, FDA approved Adaptive Biotechnologies’ clonoSEQ to detect minimal residual disease (MRD) in chronic lymphocytic leukemia (CLL). The assay uses a proprietary immunosequencing platform to detect MRD, in which a small number of cancer cells can remain after treatment. Precise measurement tools are needed to detect MRD, which can lead to cancer recurrence. A study of the test’s use in CLL found that the assay could detect a single cancer cell in 1 million healthy cells, well above the standard of 1 cell among 100,000 cells that defines MRD. Thirty months after treatment, the probability of progression for evaluable patients with undetectable MRD was 5%, as compared with 36% for patients with detectable disease. Adaptive announced the approve in a statement, which offered guidance on how to be tested during the coronavirus disease 2019 pandemic.

Liquid biopsy approved with NGS. FDA on Friday approved the Guardant360 CDx liquid biopsy for comprehensive genomic profiling, the manufacturer Guardant Health announced. The test is approved as a companion diagnostic for patients with non-small cell lung cancer (NSCLC) to identify those with EGFR mutations who might be eligible for treatment with osimertinib (Tagrisso). The approval was based on clinical and analytical validation data from more than 5,000 samples. Patients with NSCLC taking part in the phase 3 clinical trials for osimertinib, FLAURA and AURA3, which used the Guardant360 CDx assay had progression-free survival rates consistent with those found using standard biomarker testing. Company officials said in the statement that widespread adoption of a liquid biopsy will make genomic testing more accessible with faster turnaround times. On Tuesday, the FDA issued a clarification on when a biopsy should be performed, saying that "genomic findings for other biomarkers evaluated are not validated for choosing a particular corresponding treatment with this approval."

Risdiplam for spinal muscular atrophy. Also Friday, FDA approved risdiplam, an oral treatment given at home for spinal muscular atrophy (SMA). The drug from PTC Therapeutics is approved in adults and children aged two months and older. It will be marketed by Genentech as Evrysdi. Approval is based on results from two clinical studies involving more than 450 patients, which showed young patients achieved clinically meaningful improvements in motor function and achieved developmental milestones not normally seen in SMA, according to a statement from the companies. A Genentech official said the major of patients with SMA remain untreated. Existing therapies in SMA include Novartis’ onasemnogen abeparvovec (Zolgensma), a single-dose gene therapy given only to children under age 2; it costs $2.1 million.