PMC8462007_01
Immunohistochemical characterization of the resected tumor: (A) magnetic resonance imaging showing a large inhomogeneous pelvic mass with sharply delineated tumor borders and mild contrast enhancement (malignant peritoneal mesothelioma); left panel: sagittal T2-weighted image and right panel: contrast-enhanced transversal T1-weighted section with fat saturation; (B) section of the H&E stained tumor on the ovarian surface displaying a biphasic growth pattern with papillary epithelioid and sarcomatoid morphology; (C) CK5/6 immunohistochemistry was positive in the epithelioid component; (D) D2-40 immunohistochemistry exhibiting diffuse positivity in the sarcomatoid and a cap-like focal positivity in the epithelioid component; (E) Ber-EP4 was negative; (F) WT-1 reacted positive in the tumor nuclei; and (G) PAX-8 was predominantly positive in the epithelioid areas. Scale bars: 100 microm. H&E, hematoxylin and eosin; WT, wild type.
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fig1
Transvaginal sonography and magnetic resonance imaging revealed a 16 cm measuring cystic solid tumor in the Douglas cavity (Fig 1A). Ber-EP4 was completely negative (Figs 1B-1G).
Functional characterization of the STRN-ALK fusion: (A) schematic representation of the detected STRN-ALK fusion; (B) diffusely strong immunohistochemical ALK positivity in both tumor components of the primary resection specimen; scale bar: 100 microm; and (C) fluorescence in situ hybridization break apart with one red-green fused and one red signal (exemplary white arrow heads) in 68% of tumor cells, which is described as a positive break-apart pattern by the manufacturer.
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fig2
In concordance with the detected fusion gene, ALK immunohistochemistry was strongly positive (Fig 2).
Targeted therapy with crizotinib: (A) overview of the clinical course with a graphical representation of CA 12-5 values over time and corresponding therapy; (B) photodocumentation of a subcutaneous metastasis in the median laparotomy scar before crizotinib therapy in December 2019 (left panel) and February 2020 under crizotinib therapy (right panel); and (C) coronal reformations of contrast-enhanced computed tomography showing a significant reduction of the abdominal wall tumor before (left panel) and during treatment with crizotinib (right panel). CA 12-5, cancer antigen 12-5; MTB, molecular tumor board; PEG, pegylated-liposomal; PD, progressive disease; PR, partial response.
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fig3
Since crizotinib treatment was still very well-tolerated, the therapy was continued for 2 more months (Fig 3).
ALK resistance mutation and mixed response under brigatinib therapy: (A) canonical ALK downstream effectors are strongly activated in a precrizotinib biopsy (left panels) and a biopsy during crizotinib treatment harboring an ALK p.L1196M mutation (right panels) hinting at acquired resistance; scale bar = 50 microm; ERK1/2 (antibody #4370; Cell Signaling Technology, Cambridge, United Kingdom), p-mTOR (antibody #2976; Cell Signaling Technology), p-STAT3 (antibody #9145; Cell Signaling Technology), and Bcl-XL (antibody #2764; Cell Signaling Technology); and (B) coronal reformation of contrast-enhanced computed tomography scans before (left panel) and 2 months after initiation of brigatinib therapy (right panel), showing mixed response with a significant decrease of tumor diameters but new onset of liver metastases (white arrows). Bcl-XL, B-cell lymphoma-extra large; ERK1/2, extracellular signal-regulated kinases 1 and 2; H&E, hematoxylin and eosin; p-mTOR, phospho(Ser2448)-mammalian target of rapamycin; p-STAT3, phospho(Tyr705) signal transducer and activator of transcription 3.
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fig4
ALK targets, such as total extracellular signal-regulated kinases 1 and 2 (ERK1/2), phosphorylated or activated mammalian target of rapamycin (p-mTOR), signal transducer and activator of transcription 3 (p-STAT3), and total B-cell lymphoma-extra large (Bcl-XL), by immunohistochemistry of tumor biopsies before and during crizotinib treatment. Activation of ALK downstream effectors was equally strong in both settings, implying persistent ALK activity under crizotinib therapy and, thereby, treatment resistance (Fig 4A). ALK inhibitor, was recommended and initiated in July 2020 (90 mg once daily for 7 days and afterward 180 mg once daily). A CT scan in August 2020 yielded a mixed response: regression in size of parailiacal soft tissue metastases, pelvic metastases, and the abdominal wall's biopsied metastasis was detected (Fig 4B), whereas pulmonary metastases remained constant in number and diameter.