Targeted Treatment for IDH2-Mutated AML - Episode 2

Molecular Testing for Newly Diagnosed AML

Hetty E. Carraway, MD: When we evaluate a patient for an acute myeloid leukemia diagnosis, a bone marrow and aspirate is done. At that time, as we talked about, the molecular testing was sent. There are some institutions that will send that from the peripheral blood, but, at the time of diagnosis, we typically will send off that molecular panel for next-generation sequencing from the bone marrow aspirate sample. These types of tests are various; they’re varied in nature. At our institution, we have an in-house panel that allows us to test for up to 60 or even 100 genes at one time. At other institutions, they may not have the in-house capability of doing that, and they need to send out to other sites.

Furthermore, even with theIDH2mutation, there’s a real-time assay that you can send off that specifically only tests for that particular mutation. By and large, many institutions are using lots of panel-based next-generation sequencing testing formats because you can get a lot of information, and often its more cost-effective. Many of these tests can be FoundationOne, ARUP, etc. Other institutions like Novartis, have their own panels, but other institutions often have panels as well—so it can be that institutions work together to process samples. The turnaround time for this type of testing can be up to 2 weeks. For some locations, it can be longer just by the very nature of when you get the sample and when it actually arrives at the place to be tested. By and large, next-generation sequencing is now the standard of care for all of our patients with acute leukemia at the time of a new diagnosis.

In addition, comprehensive cytogenetics is also a very important test for many of our patients with a diagnosis of AML. We like to make sure that 20 cells are actually growing when comprehensive cytogenetics are done. Some institutions, at the same time, also do FISH testing for AML to make sure that good-risk or core-binding factor leukemias are ruled out or ruled in for patients, in terms of moving forward with therapy, not only in their short-term treatment but even in their long-term treatments.

Transcript edited for clarity.


A 48-Year-Old Male With Chemo-Refractory AML

  • A healthy 48-year-old man visited his PCP for flu-like symptoms lasting more than 2 weeks. He is married, with 3 school-age children and is an avid golf and tennis player.
  • PE: mild petechiae on lower extremities; otherwise unremarkable
  • Labs:
    • WBC, 65,000 (90% blasts)
    • Hb, 8.5 g/dL
    • Platelets 65,000/mL
    • ANC 2.5/mm3
    • LDH, 392 U/L
  • Bone marrow biopsy:
    • 50% blasts
    • Cytogenetics; +8
    • NGS;IDH2(R140Q) mutation
  • Liver and cardiac workup, WNL
  • The patient received 7+3 induction chemotherapy and subsequently reinduction without achieving a remission
  • The patient was then started on enasidenib
  • He achieved stable disease after 2 cycles of therapy
  • After 3 cycles, peripheral blasts, 15%; ANC, 1.1/mm3
    • 2 weeks later, patient reports dyspnea on exertion and mild swelling
    • PE notable for rales bilaterally
    • Chest X-ray shows bilateral diffuse pulmonary infiltrates
    • Additionally, indirect bilirubin, 1.9 mg/dl
    • Patient was started on dexamethasone 10 mg bid and antibiotics; pulmonary symptoms resolved in 1 week
  • Bone marrow biopsy after 6 cycles shows morphologic CR, 2% blasts by FC; NGS shows persistence of mutantIDH2
  • Patient referred for allogeneic transplant