Here we show that Pz-1 is a potent inhibitor of TRK kinases as well, that is active against several RET and TRKA mutants that are resistant to other TKIs and that is effective in xenografts of human MTC, lung and colon carcinoma cells driven by RET or TRKA oncogenes. Here, TPM3 is linked to medullary thyroid gland carcinoma.