MP-03. Successful treatment of testicular myeloid sarcoma with azacitidine and venetoclax: Case report

Summary

Myeloid sarcoma (MS) is a malignant hematopoietic tumor consisting of myeloid blasts and occurs at an anatomical site other than the bone marrow (BM). Isolated MS without overt BM disease is extremely rare. Nevertheless, according to most international expert panels, the initial treatment in such cases should still be based on systemic chemotherapy (CT). Standardized guidelines for MS treatment currently do not exist.

Case report

In October 2021, patient S., 53 years old, noticed the enlargement of his testicles. Initially he was diagnosed with orchitis/epididymitis and received antibacterial therapy, which was ineffective. According to the histologic examination performed in January 2022, a testicular peripheral T-cell lymphoma, nor otherwise specified, was diagnosed. Tumor lesion was validated with PET/CT: there was an enlargement of both testicles up to 86×50 mm with increased uptake of ¹⁸F-FDG SUVmax 8.15 (right) and 9.4 (left) (blood-pool ¹⁸F-FDG SUVmax 2.5 and liver 4.2). In April 2022, the diagnosis was revised at the National Medical Research Center for Hematology. After comprehensive examination, the diagnosis of myeloid sarcoma with testicular lesion and CNS leukemia with additional signals from RUNX1T1/8q21 and RUNX1/21q22 genes, RUNX1 gene mutation was verified. The BM disease was excluded, and peripheral blood parameters were within the normal range. From April to May 2022, the “7+3” (with idarubicin) and “HiDAC/MITO” induction regimens were performed. After two courses of chemotherapy, partial remission (Deauville score of 4) according to PET/CT was achieved: we observed normalization of testicles’ sizes, uptake of ¹⁸F-FDG SUVmax was 4.9 (blood-pool – ¹⁸F-FDG SUVmax 2.9, liver – 4.5). In parallel with chemotherapy, intrathecal administration of cytarabine, methotrexate and dexamethasone were done by lumbar punctures: CNS leukemia regressed after eight procedures. From July to August 2022 we performed two consolidation courses – both were “FLAG”. After four courses of CT, according to PET/CT, no positive dynamics was observed: the testicles were not enlarged in size, but the uptake of ¹⁸F-FDG SUVmax was 4.99 (blood-pool – ¹⁸F-FDG SUVmax 1.6, liver 3.2), and there was also a heterogeneous increased uptake of ¹⁸F-FDG SUVmax 5.4 in tubular bones, in other bones – 3.9. The histological examination of testicular tissues showed the substrate of myeloid sarcoma. Thus, after four courses of CT the desired effect was not achieved. In November 2022, radiation therapy was performed, specifically on the cranial area (24 Gy) and on the scrotum area (24 Gy). Three months later, PET/CT was done once again: testicular uptake of ¹⁸F-FDG SUVmax was 3.55 (blood-pool – ¹⁸F-FDG SUVmax 2.45, liver – 4.5) and, unfortunately, new tumors with increased metabolism appeared in pericardium area and pelvis. Thus, despite several intensive chemotherapy regimens, the disease began to progress. We decided to switch to low-dose regimens including a selective BCL-2 inhibitor venetoclax and hypomethylating agents. After three courses of “Azacitidine + Venetoclax” there were no signs of an active neoplastic process on PET/CT scans and, therefore, a complete metabolic response was achieved. Considering the remission of MS, we are planning to perform HSCT.

Conclusion

The prognosis in patients with myeloid sarcoma remains very poor, and standard chemotherapy regimens are not always effective, which underscores the necessity of search for new therapeutic strategies.

Keywords

Myeloid sarcoma, chemotherapy, venetoclax.