Pertuzumab Plus Trastuzumab for Treatment-Refractory HER2-Amplified Metastatic Colorectal Cancer: Comparison of the MyPathway Trial With a Real-World External Control Arm.

PURPOSE: We compared overall survival (OS) in patients with human epidermal growth factor receptor 2 (HER2)-amplified, treatment-refractory metastatic colorectal cancer (mCRC) receiving pertuzumab plus trastuzumab (PER-HER) in the phase IIa MyPathway multibasket study (ClinicalTrials.gov identifier: NCT02091141) with OS in those receiving routine clinical care in an electronic health record-derived external control arm. METHODS: A noninterventional study was conducted using patient-level data from MyPathway participants receiving PER-HER and real-world patients with HER2-amplified treatment-refractory mCRC receiving routine clinical care. This study used a deidentified US-based clinico-genomic database (CGDB). For patients in the CGDB who met study eligibility criteria at multiple index dates (treatment initiation dates in the treatment-refractory setting), all eligible index dates were used for the analysis. Standardized mortality ratio weighting on the basis of propensity score derived a pseudopopulation (postweighting population) balancing key prognostic variables between arms. Multivariate Cox proportional hazards models were used for estimation of the hazard ratio (HR) in the primary OS analysis. A series of sensitivity analyses were conducted to investigate the robustness and consistency of the primary analysis. RESULTS: The PER-HER arm comprised 57 patients enrolled in the MyPathway study by August 1, 2017 (data cutoff); the external control arm comprised 18 patients (27 index dates) with HER2-amplified mCRC who met the major MyPathway eligibility criteria in CGDB collected between 2011 and 2019. The estimated HR for OS from the multivariate Cox proportional hazards model in the postweighting population was 0.729 (95% CI, 0.184 to 3.900). The results of sensitivity analyses were consistent with the primary analysis in terms of the point estimate of HR. CONCLUSION: Despite a small sample size, these findings suggest that PER-HER could have a potential OS benefit for this population.

Efficacy of trastuzumab emtansine in Japanese patients with previously treated HER2-positive locally advanced or metastatic gastric or gastroesophageal junction adenocarcinoma: A subgroup analysis of the GATSBY study.

AIM: The phase II/III GATSBY study (NCT01641939) showed that trastuzumab emtansine did not have an efficacy benefit over taxane in patients with previously treated, human epidermal growth factor receptor 2 (HER2)-positive advanced or metastatic gastric or gastroesophageal junction cancer. We evaluated patients from Japanese centers within GATSBY. METHODS: In stage one, patients (randomized 2:2:1) received trastuzumab emtansine 3.6 mg/kg every 3 weeks, trastuzumab emtansine 2.4 mg/kg weekly, or physician's choice of taxane (docetaxel 75 mg/m² every 3 weeks or paclitaxel 80 mg/m² weekly). In stage two, patients (randomized 2:1) received trastuzumab emtansine 2.4 mg/kg weekly or taxane. Eligible patients had centrally assessed HER2-positive disease and progression during or after first-line therapy. Primary endpoint was overall survival. We present the 2.4 mg/kg weekly data. RESULTS: Eighty-two patients were randomized (intention-to-treat: 48 to trastuzumab emtansine 2.4 mg/kg weekly, 23 to taxane; September 2012-August 2014) at 19 sites. Median overall survival was 11.8 months (95% confidence interval [CI], 9.3-16.3) with trastuzumab emtansine 2.4 mg/kg weekly and 10.0 months (95% CI, 7.1-18.2) with taxane (unstratified hazard ratio = 0.94, 95% CI, 0.52-1.72). Trastuzumab emtansine 2.4 mg/kg weekly, versus taxane, was associated with fewer grade ≥3 adverse events (AEs; 52.1% vs 68.2%) and serious AEs (14.6% vs 18.2%). There were no fatal AEs. CONCLUSIONS: Efficacy in Japanese patients within GATSBY was consistent with the overall population; overall survival was not prolonged with trastuzumab emtansine 2.4 mg/kg weekly versus taxane. The safety profile of trastuzumab emtansine was similar to the overall population.

Pertuzumab plus trastuzumab and chemotherapy for Japanese patients with HER2-positive metastatic gastric or gastroesophageal junction cancer: a subgroup analysis of the JACOB trial.

BACKGROUND: The phase III JACOB trial (NCT01774786) compared the efficacy and safety of pertuzumab and trastuzumab plus chemotherapy with placebo and trastuzumab plus chemotherapy in patients with previously untreated human epidermal growth factor receptor 2 (HER2)-positive metastatic gastric or gastroesophageal junction cancer. We conducted a subgroup analysis in Japanese patients. METHODS: Patients were randomized 1:1 to pertuzumab 840 mg or placebo, plus trastuzumab (loading dose, 8 mg/kg; maintenance dose, 6 mg/kg) and chemotherapy (cisplatin 80 mg/m2, and capecitabine 1000 mg/m2 twice daily for 28 doses or 5-fluorouracil 800 mg/m2 every 24 h for 120 h), every 3 weeks. Continuation of chemotherapy after 6 cycles was at the discretion of the patient and the treating physician. RESULTS: A total of 40 Japanese patients were included in each arm. Median overall survival was 22.0 months (95% confidence interval [CI] 13.8-not evaluable) and 15.6 months (95% CI 9.7-19.2) in the pertuzumab and placebo arms, respectively (hazard ratio [HR] 0.64 [95% CI 0.37-1.10]). Median progression-free survival was 12.4 months (95% CI 6.1-14.1) in the pertuzumab arm and 6.3 months (95% CI 4.3-8.1) in the placebo arm (HR 0.50 [95% CI 0.30-0.82]). Grade ≥ 3 adverse events and serious adverse events were more frequent in the pertuzumab arm than the placebo arm. CONCLUSIONS: Results from this subgroup analysis of the JACOB trial suggest similar efficacy of pertuzumab in Japanese patients and patients in the overall population, encouraging continued investigation of new agents for gastric cancer in Japanese patients.