Phase II Trial of Neoadjuvant Nab-Paclitaxel in High Risk Patients With Prostate Cancer Undergoing Radical Prostatectomy

PurposeTaxane based chemotherapy has activity in advanced prostate cancer but previous studies of neoadjuvant docetaxel demonstrated a prostate specific antigen response with no obvious antitumor activity. The efficacy and safety of neoadjuvant albumin-bound paclitaxel (nab-paclitaxel, Abraxane®), a novel nanoparticle based formulation, were assessed in patients with high risk, locally advanced prostate cancer.Materials and MethodsEligible patients had locally advanced prostatic adenocarcinoma, clinical stage cT2b or greater, Gleason score 8 or greater, or serum prostate specific antigen 15 ng/ml or greater without metastatic disease. Patients received 2 cycles of 150 mg/m2 nab-paclitaxel weekly for 3 weeks during each 4-week cycle, followed by radical prostatectomy with bilateral lymphadenectomy. Efficacy assessments included pathological and prostate specific antigen response.ResultsA total of 19 patients completed neoadjuvant therapy and 18 underwent radical prostatectomy. Median pretreatment prostate specific antigen was 8.5 ng/ml and median Gleason score was 8. Despite the lack of complete pathological responses 5 of 18 patients (28%) had organ confined disease and 9 of 18 (50%) had specimen confined disease. Post-chemotherapy prostate specific antigen was decreased in 18 of 19 (95%) patients and median decrease was 2.9 ng/ml (35%, p <0.001). An initial prostate specific antigen after radical prostatectomy of 0.02 ng/ml or less was achieved in 17 of 18 (94%) patients. There were no significant perioperative complications. Cytoplasmic vacuolization (focal in 10 and extensive in 7) was evident in all but 1 patient (94%). Ten patients (56%) had grade 3 and 1 had grade 4 neutropenia with no febrile neutropenia.ConclusionsNeoadjuvant nab-paclitaxel was well tolerated. Similar to our experience with neoadjuvant docetaxel there were no pathological complete responses, although a possible histological antitumor effect was observed.