CDK4 and leiomyosarcoma: While CDKN2A deep deletions were found in 8% of leiomyosarcomas (LMS), 20% of undifferentiated pleomorphic sarcomas (UPS) and 18% of myxofibrosarcomas.14 These findings constituted the basis of the exploration of palbociclib and abemaciclib, CDK4 inhibitors, in DD-LPS.15,16 Nonetheless, the proportion of STS patients with CDK4 amplification is lower than 5% apart from DD-LPS.17 The lack of a benign counterpart in the majority of sarcoma subtypes makes it more challenging to determine what might be considered categorically the threshold of mRNA overexpression.