Tumor Boards

NTRK3 Fusion

April 2019: Patient developed occlusion of the left iliac veins due to mass effect and is started on anticoagulation.

May 2019: Patient underwent marginal resection of an 8.3 cm mass from the left hemipelvis for intermediate disease control. Pathology consistent with MPNST, pT2 disease with deep positive margins.

July 2019: First post-operative abdominal imaging demonstrates rapid recurrence/growth of the infiltrating tumor in the lower retroperitoneum extending to the iliac fossa region. The tumor increasingly obstructs the distal left ureter with resulting hydronephrosis. Ureteral stents are placed.

August 2019: Starts palliative systemic chemotherapy with docetaxel and gemcitabine. Doxorubicin was not a viable option due to cumulative lifetime exposure during adjuvant treatment ten years prior.

September 2019: CT re-staging scans after 3 cycles of chemotherapy demonstrate enlarging left retroperitoneal mass (11.8cm X 6.8cm) involving the iliopsoas with vascular occlusion and increased lytic destruction of the left anterior aspect of S1.

October 2019: Molecular profiling by Foundation One reveals STRN3-NTRK3 fusion, EGFR amplification, MDM2 amplification, CDKN2A/B loss, NKX2-1 amplification, and mutations in NF1 and SUZ12.

After discussion in soft tissue sarcoma and molecular tumor boards, her disease is deemed inoperable and larotrectinib is recommended as next-line therapy due to the NTRK3 fusion. She tolerates larotrectinib well without nausea, arthralgia or obvious neurologic symptoms. 

December 2019: Abdominal pain worsens and she is admitted for urosepsis. CT re-staging demonstrates marked interval enlargement of the pelvic mass (16.4 x 13.9 cm) with high-grade mechanical small bowel obstruction. A nasogastric tube is placed and oral intake is limited. She becomes increasingly deconditioned and weak, eventually pursuing Hospice at discharge and dying shortly thereafter.