PurposeSorafenib is a multikinase inhibitor with antiangiogenic/antiproliferative activity. A randomized, double-blind, placebo-controlled phase IIB trial assessed sorafenib with capecitabine for locally advanced or metastatic human epidermal growth factor receptor 2 (HER2) –negative breast cancer.Patients and MethodsPatients were randomly assigned to first- or second-line capecitabine 1,000 mg/m2orally twice a day for days 1 to 14 of every 21-day cycle with sorafenib 400 mg orally twice a day or placebo. The primary end point was progression-free survival (PFS).ResultsIn total, 229 patients were enrolled. The addition of sorafenib to capecitabine resulted in a significant improvement in PFS versus placebo (median, 6.4 v 4.1 months; hazard ratio [HR], 0.58; 95% CI, 0.41 to 0.81; P = .001) with sorafenib favored across subgroups, including first-line (HR, 0.50; 95% CI, 0.30 to 0.82) and second-line (HR, 0.65; 95% CI, 0.41 to 1.04) treatment. There was no significant improvement for overall survival (median, 22.2 v 20.9 months; HR, 0.86; 95% CI, 0.61 to 1.23; P = .42) and overall response (38% v 31%; P = .25). Toxicities (sorafenib v placebo) of any grade included rash (22% v 8%), diarrhea (58% v 30%), mucosal inflammation (33% v 21%), neutropenia (13% v 4%), hypertension (18% v 12%), and hand-foot skin reaction/hand- foot syndrome (HFSR/HFS; 90% v 66%); grade 3 to 4 toxicities were comparable between treatment arms except HFSR/HFS (44% v 14%). Reasons for discontinuation in the sorafenib and placebo arms included disease progression (63% v 82%, respectively), adverse events (20% v 9%, respectively), and death (0% v 1%, respectively).ConclusionAddition of sorafenib to capecitabine improved PFS in patients with HER2-negative advanced breast cancer. The dose of sorafenib used in this trial resulted in unacceptable toxicity for many patients. A phase III confirmatory trial has been initiated with a reduced sorafenib dose.

PURPOSE Pembrolizumab, a programmed death 1 inhibitor, demonstrated promising single-agent activity in untreated patients with various cancer types. The phase II KEYNOTE-427 study evaluated efficacy and safety of single-agent pembrolizumab in treatment-naive patients with advanced clear cell renal cell carcinoma (ccRCC; cohort A) and advanced non-ccRCC (cohort B). Results of cohort A are reported. METHODS In this open-label, single-arm phase II study, patients with advanced ccRCC received pembrolizumab 200 mg every 3 weeks for ≤ 24 months. The primary end point was objective response rate by RECIST, version 1.1. RESULTS In the total population (N = 110), median time from enrollment to data cutoff was 35.9 (range, 29.5-40.3) months. Objective response rate was 36.4% with four (3.6%) complete responses and 36 (32.7%) partial responses; disease control rate was 58.2% (95% CI, 48.4 to 67.5). Most patients (68.2%) had a decrease in target lesions, including 30.9% with a reduction ≥ 60%. Median duration of response was 18.9 (range, 2.3-37.6+) months; 64.1% of responders had a response ≥ 12 months (Kaplan-Meier). Median progression-free survival was 7.1 months (95% CI, 5.6 to 11.0). Median overall survival was not reached; 12-month and 24-month overall survival rates were 88.2% and 70.8%, respectively. Durable responses were observed across all International Metastatic RCC Database Consortium categories. Grade 3-5 treatment-related adverse events were reported in 30.0% of patients, of which colitis and diarrhea were most frequent. CONCLUSION Single-agent pembrolizumab showed promising antitumor activity as a first-line treatment in patients with advanced ccRCC, with durable responses across International Metastatic RCC Database Consortium categories. Safety and tolerability profile of pembrolizumab monotherapy was comparable to what has been previously described in other tumor types.

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546 Background: PD-1/L1 pathway inhibitors are effective in clear cell (cc)RCC, but efficacy of PD-1 inhibitors (or any therapy) in nccRCC has not been established. KEYNOTE-427 is a single-arm, open-label, phase 2 study of pembro monotherapy in patients (pts) with advanced ccRCC (cohort A) and nccRCC (cohort B). Cohort B results are presented. Methods: 165 pts with histologically confirmed nccRCC, no prior systemic therapy, measurable disease (RECIST v1.1), and KPS ≥70% enrolled. Pts received pembro 200 mg IV Q3W for 35 cycles (~2 y) or until progressive disease (PD), unacceptable toxicity, or withdrawal. Pts were followed after PD for overall survival. Primary end point: objective response rate (ORR) per RECIST v1.1 by blinded independent central review. Secondary end points included duration of response (DOR) and population description by International Metastatic RCC Database Consortium (IMDC) risk. Exploratory end points: ORR by histology and PD-L1 expression (combined positive score [CPS] ≥1 for PD-L1+). Results: Histology was confirmed by a central pathologist: papillary 72% (n=118), chromophobe 13% (n=21), unclassified 16% (n=26). 68% of patients were at intermediate/poor IMDC risk, and 62% were PD-L1+. At analysis, 49 pts had died and 3 had withdrawn. At a median follow-up duration of 11.1 mo (range, 0.9-21.3), 56% of pts discontinued pembro due to PD or clinical progression. Overall ORR was 24.8% (95% CI, 18.5-32.2; 8 [4.8%] CRs, 33 [20%] PRs); median DOR was not reached. ORR (95% CI) was 25.4% (17.9-34.3) with papillary, 9.5% (1.2-30.4) with chromophobe, and 34.6% (17.2-55.7) with unclassified nccRCC. ORR (95% CI) was 28.3% (16.8-42.3) with favorable and 23.2% (15.8-32.1) with intermediate/poor IMDC risk and 33.3% (24.3-43.4) and 10.3% (3.9-21.2) with CPS≥1 and CPS<1, respectively. Grade 3-5 treatment-related adverse events (TRAEs) occurred in 11% of pts; 6% discontinued due to TRAEs. 6 pts died due to AEs, 2 of which were TRAEs (pneumonia and cardiac arrest). Conclusions: Single-agent pembro showed encouraging antitumor activity in nccRCC, especially with papillary or unclassified histology. Safety profile of pembro was generally as expected. Clinical trial information: NCT02853344.

4532 Background: Pembro was approved for the treatment of locally advanced or metastatic UC that progressed during or after a platinum-containing regimen, based on the phase 3 KEYNOTE-045 (NCT02256436) trial that showed significantly improved OS with use of pembro. Updated results are presented from KEYNOTE-045 after >5 y of follow-up since the last patient (pt) was randomized. Methods: KEYNOTE-045 is a randomized, multisite, open-label, phase 3 trial. Pts with histologically or cytologically confirmed UC, progression after platinum-containing chemo, ECOG PS 0-2, measurable disease per RECIST v1.1, and ≤2 prior lines of systemic therapy were eligible. Pts were randomly assigned 1:1 to receive pembro 200 mg Q3W or investigator’s choice of paclitaxel 175 mg/m2 Q3W, docetaxel 75 mg/m2 Q3W, or vinflunine 320 mg/m2 Q3W. Primary end points are PFS (RECIST v1.1, blinded central review) and OS. ORR and duration of response (DOR) were key secondary end points. Results: As of Oct 1, 2020, among 542 enrolled pts, median time from randomization to data cutoff was 62.9 mo (range 58.6-70.9). 9.4% and 0% of pts in the pembro and chemo arms, respectively, completed 2 years of therapy. Median OS was longer for pembro vs chemo (10.1 vs 7.2 mo; HR, 0.71 [95% CI, 0.59-0.86]) overall and in pts with CPS ≥10 (8.0 vs 4.9 mo; HR, 0.59 [95% CI, 0.40-0.86]). For pts with CR or PR, median OS was not reached and 16.4 (95% CI, 11.3-25.1) mo in the pembro and chemo arms, respectively (Table). OS rates at 48 mo were 16.7% for pembro and 10.1% for chemo; 60-mo OS rates were 14.9% and 8.7%, respectively. OS benefit with pembro vs chemo continued regardless of age, ECOG PS, prior therapy, liver metastases, baseline hemoglobin, time from last chemo, histology, risk factors, and chemo choice. Median DOR for responders was longer for pembro vs chemo (29.7 mo [1.6+ to 60.5+] vs 4.4 mo [1.4+ to 63.1+]), and a greater proportion of responses lasted ≥48 mo (40.9% vs 28.3%, Kaplan-Meier) and ≥60 mo (32.8% vs 28.3%). ORR was higher for pembro vs chemo (21.9% vs 11.0%; difference 10.8% [95% CI, 4.6-17.0]). Fewer pts given pembro vs chemo experienced a treatment-related AE of any grade (62.0% vs 90.6%) or grade ≥3 (16.9% vs 50.2%). Conclusions: After 5 y, pembro maintained clinically meaningful OS benefit vs chemo in pts with locally advanced or metastatic UC that progressed during or after platinum-based chemo. Pts who responded to pembro experienced a durable response (median >2 y). Clinical trial information: NCT02256436 .[Table: see text]