STRO-002 is a novel homogeneous FolRα targeting antibody drug conjugate (ADC), currently being investigated in the clinic as a treatment for ovarian and endometrial cancers. Here we describe the discovery, optimization, and anti-tumor properties of STRO-002. STRO-002 was generated by conjugation of a novel cleavable 3-aminophenyl hemiasterlin linker-warhead (SC239) to the non-natural amino acid para-azidomethyl-L-phenylalanine (pAMF) incorporated at specific positions within a high affinity anti-FolRα antibody using Sutro's XpressCF+ , which resulted in a homogeneous ADC with a drug-antibody ratio (DAR) of 4. STRO-002 binds to FolRα with high affinity, internalizes rapidly into target positive cells, and releases the tubulin-targeting cytotoxin 3-aminophenyl hemiasterlin (SC209). SC209 has reduced potential for drug efflux via P-gp drug pumps compared to other tubulin-targeting payloads. While STRO-002 lacks non-specific cytotoxicity toward FolRα-negative cell lines, bystander killing of target negative cells was observed when co-cultured with target positive cells. STRO-002 is stable in circulation with no change in DAR for up to 21 days and has a half-life of 6.4 days in mice. A single dose of STRO-002 induced significant tumor growth inhibition in FolRα expressing xenograft models and patient derived xenograft (PDX) models. In addition, combination treatment with carboplatin or Avastin further increased STRO-002 efficacy in xenograft models. The potent and specific pre-clinical efficacy of STRO-002 supports clinical development of STRO-002 for treating patients with FolRα-expressing cancers including ovarian, endometrial, and NSCLC. Phase I dose escalation for STRO-002 is in progress in ovarian cancer patients (NCT03748186).