PMC8563073_01
Clinical course and response images of relapsed SRMS patient. Upper panel shows the timeline of treatments after relapse and progression in the patient. PET scans were obtained at relapse (January 2019) and after regimen 3 (March 2019), as well as before (April 2019) and after (June 2019) fourth-line DST-guided therapy. Before DST-guided therapy, there was progressive disease with PET demonstrating a large, FDG-avid right mass in the lower extremity with a right pelvic mass, right thigh lymph node, and right lung nodule (April 2019). PET scan obtained after 8 weeks of DST-guided therapy in June 2019 (vincristine in combination with irinotecan and temozolomide) demonstrated significantly decreased size of ill-defined soft tissue mass seen encasing the femoral neurovascular bundle (residual lower-level FDG uptake in the right thigh). In addition, interval improvement was observed in disease burden with residual masses throughout liver parenchyma, pancreatic head, and body as well as stable right middle lobe pulmonary nodule. Bottom panel shows results from our functional precision medicine platform (molecular tumor analysis and drug sensitivity testing) on the recurrent tumor. D, day; DST, drug sensitivity testing; FDG, fluorodeoxyglucose; FIU, Florida International University; IV, intravenous; NA, not available; PET, positron emission tomography; PFS, progression-free survival; SBRT, stereotactic body radiation therapy; SRMS, sclerosing and spindle cell rhabdomyosarcoma.
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In January 2019, radiologic assessment of disease revealed resolution of the pelvic mass but marked a new hepatic lesion, indicative of metastasis (see Fig 2 showing the clinical course of disease relapses and progression). Results from patient mutational profiling showed a deep deletion in CDKN2A and CDKN2B, a heterozygous L122R mutation in MYOD1 exon1 hotspot, and new single-point pathogenic mutations in GNAS and NRAS (Fig 2). In the first follow-up visit, 8 weeks following DST-guided treatment, PET imaging showed a striking decrease in the ill-defined soft tissue mass in the medial right proximal thigh and decreased nodular density intermixed with linear densities in the adjacent subcutaneous tissues of the anterior right thigh (Fig 2). The patient remained clinically disease-free for 6 months (PFS: 24 weeks), compared to 2 weeks with prior regimen (Fig 2).
Ex vivo drug sensitivity results identify top effective drugs for treatment. (A) Representative image of original RMS tumor (left) and patient-derived tumor cells (right) as visualized under light microscope. Scale bars represent 400 microm, magnification 10x. (B) Immunohistochemical staining from the tumor tissue, H&E (left), myogenin (middle), and desmin (right) magnification 100x. (C) Immunofluorescence images show patient-derived cells express RMS markers, myogenin and desmin, scale bar is 20 microm, magnification 144x. (D) Top panel shows graph plot that highlights the most effective and potent drugs on the DST performed. Drugs selected for therapy are highlighted in red boxes. The bottom panel shows dose-response curves of vincristine and irinotecan. (E) The top panel shows most effective combination drugs including irinotecan and temozolomide in combination, as well as vincristine as a single agent (red boxes). The bottom panel shows the dose-response curves of the selected drugs highlighted in red boxes. The patient treatment regimen was modified based on DST results. DAPI, 4',6-diamidino-2-phenylindole; DSS, drug sensitivity score; DST, drug sensitivity testing; H&E, hematoxylin and eosin; RMS, rhabdomyosarcoma.
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Biopsy was performed on the right proximal anterior thigh, from which excised tumor was obtained to isolate cells (Fig 3A) within 24 hours, as previously described. Histologic examination showed spindle cells with fusiform nuclei, arranged in fascicles in a background of sclerosing stroma with islands of dense hyalinized collagen along with strong nuclear myogenin and cytoplasmic desmin positivity, typical of RMS (Fig 3B). We also confirmed that patient-derived cells used for DST expressed myogenin and desmin, similar to the originating tumor (Fig 3C). A ranked list of the most potentially therapeutic drugs was generated using dose-response curves, as previously described, and communicated to the Molecular Tumor Board within 7 days postsurgery (Fig 3D). As profiling took up to 3 weeks, the Molecular Tumor Board first analyzed DST results to choose effective, available drug options (Fig 3D) to begin patient treatment. DST was performed using drugs with the best individual scores. Drug sensitivity score for vincristine alone were higher than in combination with temozolomide or irinotecan (Fig 3E).