CLM29, a multi-target pyrazolopyrimidine derivative, has anti-neoplastic activity in medullary thyroid cancer in vitro and in vivo.

CLM29 (a pyrazolo[3,4-d]pyrimidine, that inhibits RET, epidermal growth factor receptor, vascular endothelial growth factor receptor, and has an anti-angiogenic activity) has anti-neoplastic activity in papillary dedifferentiated thyroid cancer. Here we tested CLM29 in medullary thyroid cancer (MTC), in primary MTC cells (P-MTC) obtained at surgery, and in TT cells harboring (C634W) RET mutation. CLM29 (10, 30, 50 µM) inhibited significantly (P<0.001) the proliferation, and increased the percentage of apoptotic P-MTC, TT and human dermal microvascular endothelial cells. The inhibition of proliferation by CLM29 was similar in P-MTC cells with/without RET mutation. TT cells were injected sc in CD nu/nu mice, and tumor masses became detectable between 20 and 30 days after xenotransplantation; CLM29 (50mg/kg/die) reduced significantly tumor growth and weight, and microvessel density. The anti-tumor activity of CLM29 has been shown in MTC in vitro, and in vivo, opening the way to a future clinical evaluation.