Response-guided neoadjuvant sacituzumab govitecan for localized triple-negative breast cancer: results from the NeoSTAR trial.

BACKGROUND: Sacituzumab govitecan (SG), a novel antibody-drug conjugate (ADC) targeting TROP2, is approved for pre-treated metastatic triple-negative breast cancer (mTNBC). We conducted an investigator-initiated clinical trial evaluating neoadjuvant (NA) SG (NCT04230109), and report primary results. PATIENTS AND METHODS: Participants with early-stage TNBC received NA SG for four cycles. The primary objective was to assess pathological complete response (pCR) rate in breast and lymph nodes (ypT0/isN0) to SG. Secondary objectives included overall response rate (ORR), safety, event-free survival (EFS), and predictive biomarkers. A response-guided approach was utilized, and subsequent systemic therapy decisions were at the discretion of the treating physician. RESULTS: From July 2020 to August 2021, 50 participants were enrolled (median age = 48.5 years; 13 clinical stage I disease, 26 stage II, 11 stage III). Forty-nine (98%) completed four cycles of SG. Overall, the pCR rate with SG alone was 30% [n = 15, 95% confidence interval (CI) 18% to 45%]. The ORR per RECIST V1.1 after SG alone was 64% (n = 32/50, 95% CI 77% to 98%). Higher Ki-67 and tumor-infiltrating lymphocytes (TILs) were predictive of pCR to SG (P = 0.007 for Ki-67 and 0.002 for TILs), while baseline TROP2 expression was not (P = 0.440). Common adverse events were nausea (82%), fatigue (76%), alopecia (76%), neutropenia (44%), and rash (48%). With a median follow-up time of 18.9 months (95% CI 16.3-21.9 months), the 2-year EFS for all participants was 95%. Among participants with a pCR with SG (n = 15), the 2-year EFS was 100%. CONCLUSIONS: In the first NA trial with an ADC in localized TNBC, SG demonstrated single-agent efficacy and feasibility of response-guided escalation/de-escalation. Further research on optimal duration of SG as well as NA combination strategies, including immunotherapy, are needed.

A feasibility study of low-dose, prolonged oral topotecan in patients with advanced ovarian, fallopian tube, or primary peritoneal serous cancer who have attained a complete clinical response following platinum-based chemotherapy.

To determine the tolerability of oral maintenance topotecan when administered to patients with advanced ovarian, fallopian tube, and primary peritoneal serous cancers who have achieved a complete clinical response after first-line platinum-based therapy. Oral topotecan was given at a starting dose of 0.4 mg/m(2)/dose, twice a day (BID) for 21 consecutive days out of 28 days. The dose was subsequently increased to 0.5 mg/m(2)/dose, twice a day as tolerated. If the patient experienced toxicities during cycle 1 or subsequent cycles, doses were delayed and/or reduced. The lowest dose allowed on protocol was 0.3 mg/m(2)/dose twice daily. Thirteen patients were enrolled in the study, representing a total of fifty-nine cycles of oral topotecan. The starting dose of 0.4 mg/m(2) by mouth (PO) BID for 21 days was generally difficult for patients to tolerate, usually due to progressive anemia and fatigue, and a dose reduction to 0.3 mg/m(2) was necessary in 10/13 patients. A median of six cycles was administered, although 6 of 13 patients could not tolerate the planned 6 cycles due to toxicity. Hematologic toxicity was the most common side effect, although there were no episodes of febrile neutropenia. Diarrhea was the most common nonhematologic side effect, occurring in 8 of 13 patients. Six patients were removed from the study prior to completing the planned six cycles of therapy, after receiving a median number of 2.5 cycles of treatment. This dose and schedule of oral topotecan does not appear to be feasible in this patient population.