Citations

9505 Background: D (BRAF inhibitor) + T (MEK inhibitor) combination therapy is associated with rapid clinical responses and has improved clinical outcomes in pts with BRAFV600–mutant MM, but long-term (˃ 3 y) clinical efficacy and safety data are limited. The longest follow-up to date of a randomized trial evaluating D+T at the approved dose (150 mg BID/2 mg QD [150/2]) was of the phase II study BRF113220 (part C; median, 45.6 mo) in which durable outcomes were achieved in some pts with BRAFV600–mutant MM (3-y OS, 38%). Here, we report updated 5-y landmark analyses to further characterize the impact of D+T in MM. Methods: Pts with BRAFV600–mutant mm enrolled in BRF113220 part C (NCT01072175) were randomized 1:1:1 to receive monotherapy D (150 mg BID), D+T (150 mg BID/1 mg QD), or D+T (150/2). Pts who progressed on D alone could cross over to the D+T 150/2 arm. Pt disposition, pt demographics, and 4- and 5-y efficacy and safety were analyzed for both the D-alone and D+T (approved 150/2 dose) arms. Results: This updated analysis represents an additional ≈ 2 y of follow-up (D and D+T arms; n = 54 each). As of 13 Oct 2016, 45 pts (83%) on D alone had crossed over to D+T. 20 pts were ongoing (D, n = 7 [13%]; D+T, n = 13 [24%]); 80% of D pts and 70% of D+T pts had died. D+T OS remained superior to D alone. The 4- and 5-y OS rates with D+T were 30% and 28%, respectively, demonstrating a stabilization of the OS curve. The PFS curve for D+T also remained stable (4- and 5-y: both 13%). Consistent with earlier results, the best OS for pts who received D+T was seen in pts with normal LDH (5-y, 45%) and normal LDH with disease in < 3 organ sites (5-y, 51%). At the 5-y landmark, 1 additional pt who received D+T improved from a partial to a complete response. Additional follow-up revealed no new safety signals with D+T. Detailed analyses of D crossover pts, responders, and post-progression therapy will be presented. Conclusions: This longest follow-up to date of BRAF + MEK inhibitor combination therapy in pts with BRAFV600–mutant mm revealed stable OS and PFS lasting ≥ 5 y with consistent tolerability. These results demonstrate that some pts with mm can achieve durable benefit with D+T therapy. Clinical trial information: NCT01072175.

9517 Background: Although PD-1/L1 axis directed therapies induce durable responses in some mm patients (pts), biomarkers of response remain elusive. We hypothesized that quantifying key immune suppression mechanisms within the tumor microenvironment would provide superior predictors of response to anti-PD-1 compared with single marker assessment. Methods: Pre-treatment tumor biopsies from 124 mm pts treated with anti-PD-1 at 7 academic centers were fluorescently stained with multiple immune markers in discovery (n = 24) and validation (n = 100) cohorts. Selected biomarker signatures, PD-1/PD-L1 interaction score (proportion of PD-1+ cells co-localized with PD-L1) and IDO1/HLA-DR co-expression were evaluated for anti-PD-1 treatment response and survival. Slides were imaged using Vectra; biomarker positive cells and their co-localization were objectively quantified in pathologist-selected regions using novel Automated Quantitative Analysis (AQUA) algorithms. Results: In the discovery cohort, high levels of PD-1/PD-L1 interaction score and/or IDO1/HLA-DR coexpression was strongly positively associated with response to anti-PD-1 (p = 0.0005). In contrast, other individual biomarkers (PD-1, PD-L1, CD8) were not associated with response or survival (p > 0.10). This finding was replicated in the validation cohort: pts with high PD-1/PD-L1 and/or IDO1/HLA-DR were more likely to respond to treatment (p = 0.009). These pts also experienced a three-fold increase in progression free survival (hazards ratio (HR) = 0.33; p = 0.003) and overall survival (HR = 0.34; p = 0.004). Multivariate analyses revealed that these findings were independent of BRAF mutation, stage, LDH and prior therapy. In the combined cohort (n = 124), 80% of responding pts had higher levels of PD-1/PD-L1 interaction scores and/or IDO1/HLA-DR. In contrast, PD-L1 expression alone (≥1% or ≥50%) was not predictive of PFS or OS (p > 0.1). Conclusions: This novel multiplexed method profiling key tumor-immune suppression pathways identified mm pts likely to respond to anti-PD-1 therapy. This method could help stratify patients for PD-1 monotherapy and be useful in guiding future clinical trials.

Abstract Purpose: PD-1/L1 axis–directed therapies produce clinical responses in a subset of patients; therefore, biomarkers of response are needed. We hypothesized that quantifying key immunosuppression mechanisms within the tumor microenvironment by multiparameter algorithms would identify strong predictors of anti–PD-1 response. Experimental Design: Pretreatment tumor biopsies from 166 patients treated with anti–PD-1 across 10 academic cancer centers were fluorescently stained with multiple markers in discovery (n = 24) and validation (n = 142) cohorts. Biomarker-positive cells and their colocalization were spatially profiled in pathologist-selected tumor regions using novel Automated Quantitative Analysis algorithms. Selected biomarker signatures, PD-1/PD-L1 interaction score, and IDO-1/HLA-DR coexpression were evaluated for anti–PD-1 treatment outcomes. Results: In the discovery cohort, PD-1/PD-L1 interaction score and/or IDO-1/HLA-DR coexpression was strongly associated with anti–PD-1 response (P = 0.0005). In contrast, individual biomarkers (PD-1, PD-L1, IDO-1, HLA-DR) were not associated with response or survival. This finding was replicated in an independent validation cohort: patients with high PD-1/PD-L1 and/or IDO-1/HLA-DR were more likely to respond (P = 0.0096). These patients also experienced significantly improved progression-free survival (HR = 0.36; P = 0.0004) and overall survival (HR = 0.39; P = 0.0011). In the combined cohort, 80% of patients exhibiting higher levels of PD-1/PD-L1 interaction scores and IDO-1/HLA-DR responded to PD-1 blockers (P = 0.000004). In contrast, PD-L1 expression was not predictive of survival. Conclusions: Quantitative spatial profiling of key tumor-immune suppression pathways by novel digital pathology algorithms could help more reliably select melanoma patients for PD-1 monotherapy. Clin Cancer Res; 24(21); 5250–60. ©2018 AACR.

Abstract Purpose: The purpose of this study was to assess the association of baseline tumor size (BTS) with other baseline clinical factors and outcomes in pembrolizumab-treated patients with advanced melanoma in KEYNOTE-001 (NCT01295827). Experimental Design: BTS was quantified by adding the sum of the longest dimensions of all measurable baseline target lesions. BTS as a dichotomous and continuous variable was evaluated with other baseline factors using logistic regression for objective response rate (ORR) and Cox regression for overall survival (OS). Nominal P values with no multiplicity adjustment describe the strength of observed associations. Results: Per central review by RECIST v1.1, 583 of 655 patients had baseline measurable disease and were included in this post hoc analysis. Median BTS was 10.2 cm (range, 1–89.5). Larger median BTS was associated with Eastern Cooperative Oncology Group performance status 1, elevated lactate dehydrogenase (LDH), stage M1c disease, and liver metastases (with or without any other sites; all P ≤ 0.001). In univariate analyses, BTS below the median was associated with higher ORR (44% vs. 23%; P &lt; 0.001) and improved OS (HR, 0.38; P &lt; 0.001). In multivariate analyses, BTS below the median remained an independent prognostic marker of OS (P &lt; 0.001) but not ORR. In 459 patients with available tumor programmed death ligand 1 (PD-L1) expression, BTS below the median and PD-L1–positive tumors were independently associated with higher ORR and longer OS. Conclusions: BTS is associated with many other baseline clinical factors but is also independently prognostic of survival in pembrolizumab-treated patients with advanced melanoma. Clin Cancer Res; 24(20); 4960–7. ©2018 AACR. See related commentary by Warner and Postow, p. 4915