Inflammatory myofibroblastic tumor (IMT), also known as plasma cell granuloma, inflammatory pseudotumor, fibrous histiocytoma, fibrous xanthoma, and xanthogranuloma, is a tumor composed of smooth muscle cells, connective tissue cells, and immune cells. Composed of rare moderate malignant tumors, belonging to a class of soft tissue sarcomas.
IMT is a special tumor, because most of the tumors are not very invasive and rarely metastasize, so it is difficult to be classified as a malignant tumor, but there are also some cases with a high degree of malignancy, which deserves vigilance.
IMT is composed of inflammatory cells and interstitial spindle cells. It can occur in any part, but it is more common in the lung (pulmonary inflammatory myofibroblastic tumor) and the soft tissue of the pelvis and abdomen. It is more common in the soft tissue and parenchymal organs of children and young adults.
There is no standard therapy for IMT, and surgical resection remains the mainstay of treatment. Complete resection of a single solitary lesion may be curative, but there is a possibility of recurrence after treatment. For inoperable patients, chemotherapy, glucocorticoids, and non-steroidal anti-inflammatory drugs can also be used.
However, about 70% of IMT cases carry ALK gene alterations, which means targeted therapy is expected to become the standard treatment option.
Recently, the U.S. Food and Drug Administration approved the ALK-targeted drug crizotinib (Xalkori) for the treatment of adult and pediatric patients 1 year and older with unresectable, relapsed, or refractory inflammatory ALK-positive myofibroblastic tumor (IMT). .
Crizotinib, an ALK tyrosine kinase inhibitor, was previously approved by the FDA for the treatment of patients with ALK-positive or ROS1-positive metastatic non-small cell lung cancer, as well as certain patients with systemic anaplastic large cell lymphoma.
The latest approval of crizotinib is based on safety and efficacy results from two multicenter, single-arm, open-label trials, ADVL0912 and A8081013, whose primary endpoint was objective response rate (ORR).
The results show
In the ADVL0912 trial, the ORR was 86% in 14 pediatric patients;
In the A8081013 trial, the ORR was 71% in seven adult patients;
The most common adverse reactions in pediatric patients were vomiting, nausea, diarrhea, abdominal pain, rash, visual disturbances, upper respiratory tract infection, cough, fever, musculoskeletal pain, fatigue, edema, constipation, and headache.
The most common adverse reactions in adult patients were visual disturbances, nausea, and edema.
Recommended dosage of Xalkori
The recommended dose for pediatric patients is 280 mg/m2 orally twice a day.
The recommended dose for adult patients is 250 mg orally twice a day.
IMT is classified by WHO as an intermediate malignancy, and in most cases, childhood inflammatory myofibroblastic tumors are benign, with an overall survival rate of over 90%.
However, the treatment of childhood cancer needs to be cautious, so that the side effects of treatment (such as second primary cancer) will not affect the child’s life. The approval of precision therapies such as targeted therapy will undoubtedly bring good news to IMT patients.