FDA Approves First Avapritinib CDx for PDGFRA Exon 18 Detection


After more than 2 years without, the FDA has approved a companion diagnostic to identity candidates for treatment with avapritinib.

  • The therascreen PDGFRA RGQ PCR kit is the 12th companion diagnostic (CDX) for QIAGEN.

  • The Therascreen protocol has FDA indications as a CDx for gefitinib (Iressa) and afatinib (Gilotrif) to detect EGFR mutations.

  • Avapritinib was granted FDA approval in 2020 for the treatment of adults with unresectable or metastatic gastrointestinal stromal tumor (GIST) who harbor platelet-derived growth factor receptor alpha (PDGFRA) exon 18 mutations, including PDGFRA D842V mutations.

The FDA has granted approval to the therascreen PDGFRA RGQ PCR kit, a CDx for avapritinib (Ayvakit), which can help identify patients unresectable or metastatic GIST that is positive for the PDGFRA D842V mutation and who may be eligible for treatment with the agent.1

The therascreen PDGFRA RGQ PCR kit is the first is the first PDGFRA assay to be granted approval by the FDA as a CDx.

Studies shows that the therascreen PDGFRA RGQ PCR kit can detect the D842V somatic mutation in the PDGFRA gene to determine if patients are eligible to be treated with avapritinib. It does so by accessing genomic DNA taken from a patient’s formalin-fixed paraffin-embedded (FFPE) tumor tissue. Then, these tumor tissues are handled by using the QIAamp DSP DNA FFPE Tissue Kit and Rotor-Gene Q (RGQ) MDx instrument for DNA to prepare, amplify, and detect any mutations.

“The therascreen PDGFRA kit is an FDA-approved and validated test, delivering results in a fast turnaround time. This ensures that physicians receive results promptly, enabling them to make informed treatment decisions for their [patients with] GIST in a timely and effective manner,” said Jonathan Arnold, vice president and head of Translational Science and Precision Diagnostics at QIAGEN, in a press release. “This latest approval confirms QIAGEN’s leadership in companion diagnostics development. It adds to QIAGEN’s extensive list of now 12 FDA-approved companion diagnostics.”

For the past 2 and a half years, there was no CDx approved to help identify candidates for avapritinib3, which was granted FDA approval based on the phase 1 NAVIGATOR trial (NCT02508532). The study included 204 patients with unresectable or metastatic gastrointestinal stromal tumor (GIST) who harbor a PDGFRA exon 18 mutation.1,4

Overall, treatment with avapritinib led to durable responses in 43 patients with PDGFRA exon 18 mutations. The objective response rate (ORR) in these patients was 84% and of those responses, 7% were complete responses (CRs) and 77% were partial responses (PRs). In patients with PDGFRA D842V mutations, the ORR was 89% (95% CI, 75-97). Of these objective responses, 8% were CRs and 82% were PRs. The median duration of response was not reached in either group of patients.

The most common adverse events were edema, nausea, fatigue/asthenia, cognitive impairment, vomiting, decreased appetite, diarrhea, hair color changes, increased lacrimation, abdominal pain, constipation, rash, and dizziness. These AEs occurred in 20% of the patients.


1. QIAGEN receives FDA approval for companion diagnostic to Blueprint Medicines’ AYVAKIT® (avapritinib) in gastrointestinal stromal tumors. News release. August 7, 2023. Accessed August 8, 2023. https://tinyurl.com/4d4jvp4w

2. therascreen EGFR RGQ PCR Kit. Qiagen. Accessed August 8, 2023. https://tinyurl.com/mryrdpkj

3. Jørgensen, JT. Missing companion diagnostic for us food and drug administration–approved hematological and oncological drugs. JCO Precis Oncol. 2022 Jun;6:e2200100. doi:10.1200/PO.22.00100.

4. Heinrich MC, Jones RL, von Mehren M, et al. Avapritinib in advanced PDGFRA D842V-mutant gastrointestinal stromal tumour (NAVIGATOR): a multicentre, open-label, phase 1 trial. Lancet Oncol. 2020;21(7):935-946. doi:10.1016/S1470-2045(20)30269-2

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