Efficacy and safety of nanoparticle albumin-bound paclitaxel plus carboplatin as neoadjuvant chemotherapy for stages III-IV, unresectable ovarian cancer: a single-arm, open-label, phase Ib/II study.

Background: Neoadjuvant chemotherapy may be considered for patients with ovarian cancer (OC) whose tumors are deemed unlikely to be completely cytoreduced to no gross residual disease (R0) or who are poor surgical candidates. This Ib/II study was designed to assess the efficacy and safety of nanoparticle albumin-bound paclitaxel (nab-paclitaxel) plus carboplatin as neoadjuvant chemotherapy for stages III-IV, unresectable OC.

Methods: Eligible patients with stage III-IV, unresectable OC were enrolled in this phase Ib/II study. All patients received neoadjuvant nab-paclitaxel (260 mg/m², day 1, every 3 weeks) plus carboplatin (AUC 5, day 1, every 3 weeks) for 3 cycles before surgery, followed by 3-6 cycles of adjuvant chemotherapy. The phase Ib primary endpoint was safety; the phase II primary endpoint was the R0 resection rate. Secondary endpoints were progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and safety (for all populations).

Results: Sixty-two patients were enrolled and were given neoadjuvant therapy treated between October 2019 and December 2020, of whom 9 were in the phase Ib portion and 53 in the phase II portion. A total of 53 patients underwent surgery with an R0 resection rate of 73.6% (95% CI, 59.7-84.7%). With a median follow-up of 17.5 (range 0.7-36.7) months, for all patients, the best ORR was 83.9% (95% CI, 71.7-92.4%) with 47 partial responses, the median PFS was 18.6 (95% CI, 13.8-23.3%) months, and median OS was not reached. During the neoadjuvant chemotherapy, treatment-related adverse events (TRAEs) of any grade occurred in 91.9% (57/62) of all patients. The most common hematologic TRAEs were neutropenia (55/62, 88.7%), and non-hematologic toxicity was alopecia (36/62, 58.1%). Forty-nine patients (79.0%) experienced at least one grade 3-4 TRAEs, with the most common was neutropenia (44/62, 71.0%). Besides, delays in neoadjuvant chemotherapy and surgery due to AEs were observed in 9 (1 in phase Ib; 8 in phase II) and 7 (phase II) patients, respectively.

Conclusions: The study demonstrated an encouraging efficacy and manageable safety profile of neoadjuvant chemotherapy nab-paclitaxel plus carboplatin in stage III-IV, unresectable OC. In addition, AEs resulting in chemotherapy and surgery delays should be cautiously considered in this clinical setting.

Trial registration: ClinicalTrials.gov, ChiCTR1900026893. Registered at 25 October 2019.