BACKGROUNDProgrammed death 1 (PD-1) blockade has clinical benefit in microsatellite-instability-high (MSI-H) or mismatch-repair-deficient (dMMR) tumors after previous therapy. The efficacy of PD-1 blockade as compared with chemotherapy as first-line therapy for MSI-H-dMMR advanced or metastatic colorectal cancer is unknown. METHODSIn this phase 3, open-label trial, 307 patients with metastatic MSI-H-dMMR colorectal cancer who had not previously received treatment were randomly assigned, in a 1:1 ratio, to receive pembrolizumab at a dose of 200 mg every 3 weeks or chemotherapy (5-fluorouracil-based therapy with or without bevacizumab or cetuximab) every 2 weeks. Patients receiving chemotherapy could cross over to pembrolizumab therapy after disease progression. The two primary end points were progression-free survival and overall survival. RESULTSAt the second interim analysis, after a median follow-up (from randomization to data cutoff) of 32.4 months (range, 24.0 to 48.3), pembrolizumab was superior to chemotherapy with respect to progression-free survival (median, 16.5 vs. 8.2 months; hazard ratio, 0.60; 95% confidence interval [CI], 0.45 to 0.80; P = 0.0002). The estimated restricted mean survival after 24 months of follow-up was 13.7 months (range, 12.0 to 15.4) as compared with 10.8 months (range, 9.4 to 12.2). As of the data cutoff date, 56 patients in the pembrolizumab group and 69 in the chemotherapy group had died. Data on overall survival were still evolving (66% of required events had occurred) and remain blinded until the final analysis. An overall response (complete or partial response), as evaluated with Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1, was observed in 43.8% of the patients in the pembrolizumab group and 33.1% in the chemotherapy group. Among patients with an overall response, 83% in the pembrolizumab group, as compared with 35% of patients in the chemotherapy group, had ongoing responses at 24 months. Treatment-related adverse events of grade 3 or higher occurred in 22% of the patients in the pembrolizumab group, as compared with 66% (including one patient who died) in the chemotherapy group. CONCLUSIONSPembrolizumab led to significantly longer progression-free survival than chemotherapy when received as first-line therapy for MSI-H-dMMR metastatic colorectal cancer, with fewer treatment-related adverse events. (Funded by Merck Sharp and Dohme and by Stand Up to Cancer; KEYNOTE-177 ClinicalTrials.gov number, NCT02563002.

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This study demonstrates feasibility and proof-of-concept of class I PI3K inhibition in patients with advanced cancers. BKM120, at the MTD of 100 mg/d, is safe and well tolerated, with a favorable PK profile, clear evidence of target inhibition, and preliminary antitumor activity.

BACKGROUNDWomen with HER‐2 overexpressing metastatic breast carcinoma benefit from trastuzumab‐based therapy, but trastuzumab does not cross the blood‐brain barrier. The authors characterized central nervous system (CNS) disease in these women.METHODSUsing pharmacy records, the authors retrospectively identified 153 women treated with trastuzumab alone or with chemotherapy for HER‐2–positive metastatic breast carcinoma at Dana‐Farber Partners Cancer Care from June 1998 to December 2000. A study cohort of 122 patients was identified after excluding patients without adequate clinical follow‐up or who had CNS disease before trastuzumab treatment. Central nervous system disease was defined as one or more brain metastases or as leptomeningeal carcinomatosis. The median follow‐up of this cohort was 23 months.RESULTSCentral nervous system metastases were identified in 34% of patients (95% confidence interval, 26–44%) at a median of 16 months after diagnosis of metastatic breast carcinoma and 6 months from the beginning of trastuzumab therapy. Ninety‐three percent of patients with CNS disease presented with clinical symptoms. Five percent of patients with CNS disease had leptomeningeal involvement alone, although 14% had leptomeningeal involvement and parenchymal brain metastases. Fifty percent of patients were responding or had stable disease while receiving trastuzumab at other disease sites at the time of diagnosis of CNS metastasis. The median survival period after CNS metastases was 13 months. Fifty percent of patients died of progressive CNS disease. Patients receiving trastuzumab as first‐line therapy for metastatic disease frequently developed brain metastases while responding to or stable on trastuzumab at other disease sites.CONCLUSIONSMetastatic breast carcinoma to the CNS is common among patients receiving trastuzumab‐based therapy, including patients responding to therapy outside the CNS. This may be due either to predilection for the CNS by HER‐2–positive tumor cells and/or poor penetration of the CNS by trastuzumab or to improved visceral disease control leading to a longer life and onset of late tumor spread to the CNS. Efforts to characterize other risk factors for development of CNS disease, optimal screening algorithms, and new treatment strategies may be warranted. Cancer 2003;97:2972–7. © 2003 American Cancer Society.DOI 10.1002/cncr.11436