This multicenter, phase II study (NCT03872791) aims to evaluate the efficacy and safety of the anti-PD-L1/CTLA-4 bispecific antibody KN046 combined with nab-paclitaxel in the first-line treatment of patients with metastatic triple-negative breast cancer (TNBC). The primary endpoints included objective response rate (ORR) and duration of response (DoR), and secondary endpoints included progression-free survival (PFS), overall survival (OS) rate, safety, and the correlation of PD-L1 status with clinical efficacy. This trial met pre-specified endpoints. 27 female patients were enrolled sequentially to receive KN046 in two dose levels (3 mg/kg or 5 mg/kg). Among the 25 evaluable patients, the ORR achieved 44.0% (95% CI, 24.4% − 65.1%), and the median DoR was not mature. The median PFS reached 7.33 months (95%CI, 3.68 − 11.07 months), and the median OS was 30.92 months (95%CI, 14.75 - NE months). In PD-L1 positive patients, PFS was 8.61 months (versus 4.73 months) and the 2-year OS rate was 62.5% (versus 57.1%) compared to PD-L1 negative patients. Patients tolerated well the combination therapy. In general, KN046 combined with nab-paclitaxel showed favorable efficacy and survival benefits with tolerable toxicity in the first-line treatment of metastatic TNBC, especially PD-L1 positive, which is worth further investigation.

Purpose: The Chinese bridging study PUFFIN (NCT02896855) aimed to assess consistency of efficacy with CLEOPATRA (NCT00567190), investigating pertuzumab with trastuzumab and docetaxel versus placebo, trastuzumab, and docetaxel in patients with previously untreated HER2-positive locally recurrent or metastatic breast cancer. Methods: Patients were randomized 1:1, stratified by visceral/non-visceral disease and hormone receptor status. The primary endpoint was investigator-assessed progression-free survival (PFS). Secondary endpoints included objective response rate (in patients with measurable baseline disease), overall survival, and safety. The consistency threshold for PFS (hazard ratio [HR] < 0.81) (maintaining ≥ 50% of the risk reduction determined in CLEOPATRA [HR 0.62]) determined the target sample size (n = 240). Results: Two hundred forty-three patients were randomized. Median PFS was 14.5 months in the pertuzumab arm (95% confidence interval [CI] 12.5, 18.6) and 12.4 months in the placebo arm (95% CI 10.4, 12.7) in the intention-to-treat population (HR: 0.69 [95% CI 0.49, 0.99]). Objective responses were recorded in 83/105 (79.0%) and 67/97 (69.1%) patients, respectively. Grade ≥ 3 adverse events (70.5% and 69.2%, respectively) and serious adverse events (19.7% and 19.2%, respectively) were similar across both arms. No heart failure cases or symptomatic left ventricular ejection fraction declines were reported. Conclusions: PUFFIN met its primary objective. Overall, efficacy data were consistent with CLEOPATRA. Safety was consistent with the known pertuzumab safety profile. PUFFIN adds to the totality of data with pertuzumab in previously untreated HER2-positive locally recurrent or metastatic breast cancer and supports the favorable benefit–risk profile of pertuzumab in Chinese patients Trial registration: ClinicalTrials.gov, NCT02896855, registered 7 September 2016

Purpose: PUFFIN (NCT02896855), a Chinese bridging study in patients with previously untreated HER2-positive locally recurrent or metastatic breast cancer, assessed consistency of efficacy and safety of pertuzumab plus trastuzumab and docetaxel versus placebo, trastuzumab, and docetaxel, with CLEOPATRA (NCT00567190). Methods: Eligible patients, n = 243, were randomized 1:1, stratified by visceral disease and hormone receptor status, to pertuzumab, trastuzumab, and docetaxel or placebo, trastuzumab, and docetaxel. Primary endpoint: investigator-assessed progression-free survival (PFS). Secondary endpoints: safety and overall survival (OS). After primary analysis, patients could cross over to the pertuzumab arm. Results: Updated median PFS: 16.5 months (pertuzumab arm) and 12.5 months (placebo arm), with a hazard ratio (HR) of 0.60 [95% confidence interval (CI) 0.45, 0.81; p = 0.0008]. Median OS was not reached in either arm; the OS HR was 0.68 (95% CI 0.45, 1.03; p = 0.0658). Safety was similar in both arms with no new safety signals: 73.8% (pertuzumab arm) and 69.2% (placebo arm) experienced grade ≥ 3 adverse events. No heart failure, symptomatic left ventricular systolic dysfunction, or left ventricular ejection fraction decline of < 40% were reported. Conclusions: The PUFFIN final analysis showed, per the primary analysis, that overall efficacy of pertuzumab plus trastuzumab and docetaxel was consistent with CLEOPATRA. Safety remained consistent with the known pertuzumab profile. Overall, PUFFIN contributes to the totality of data with pertuzumab in previously untreated HER2-positive locally recurrent or metastatic breast cancer and supports the favorable benefit–risk profile of pertuzumab in Chinese patients. Trial registration: ClinicalTrials.gov, NCT02896855, registered 7 September 2016.