Algazi, Alain P.

Abstract Purpose: Tilsotolimod is an investigational synthetic Toll-like receptor 9 (TLR9) agonist that has demonstrated antitumor activity in preclinical models. The ILLUMINATE-101 phase I study explored the safety, dose, efficacy, and immune effects of intratumoral (it) tilsotolimod monotherapy in multiple solid tumors. Patients and Methods: Patients with a diagnosis of refractory cancer not amenable to curative therapies received tilsotolimod in doses escalating from 8 to 32 mg into a single lesion at weeks 1, 2, 3, 5, 8, and 11. Additional patients with advanced malignant melanoma were enrolled into an expansion cohort at the 8 mg dose. Objectives included characterizing the safety, establishing the dose, efficacy, and immunologic assessment. Blood samples and tumor biopsies of injected and noninjected lesions were obtained at baseline and 24 hours after treatment for immune analyses. Results: Thirty-eight and 16 patients were enrolled into the dose escalation and melanoma expansion cohorts, respectively. Deep visceral injections were conducted in 91% of patients. No dose-limiting toxicities (DLT) or grade 4 treatment-related adverse events were observed. Biopsies 24 hours after treatment demonstrated an increased IFN pathway signature and dendritic cell maturation. Immunologic profiling revealed upregulation of IFN-signaling genes and modulation of genes for checkpoint proteins. In the dose escalation cohort, 12 (34%) of 35 evaluable patients achieved a best overall response rate (ORR) of stable disease (SD), whereas 3 (19%) of 16 evaluable patients in the melanoma cohort achieved stable disease. Conclusions: Overall, tilsotolimod monotherapy was generally well tolerated and induced rapid, robust alterations in the tumor microenvironment. See related commentary by Punekar and Weber, p. 5007

9005 Background: Dual inhibition of the MAP kinase (MAPK) pathway with dabrafenib (D) and trametinib (T) in combination has demonstrated clinical benefit compared to D alone in a randomized Phase II trial in V600 BRAF-mutant MM pts, thus delaying the development of BRAFi resistance. Little is known about the efficacy of D + T after BRAFi resistance has been acquired. This analysis evaluates the ability of D + T combination to treat acquired resistance compared to the D + T combination as first-line treatment. Methods: These data from a phase I/II study include 1. BRAFi-resistant group: pts who received 150/2 D+T in Part B (n=26) and Part C (n=43) following progression on BRAFi monotherapy (mono); 2. BRAFi-naïve group: pts who received initial 150/2 D+T in Part B (n=24) and Part C (n=54). Results: Baseline characteristics (ECOG PS, M staging, LDH) were similar across all groups.In the Part B BRAFi-resistant group, 93% of pts previously received D or vemurafenib and all pts received D prior to D+T in Part C. In BRAFi-resistant group, prior best response of CR/PR (38%, 56%), SD (35%, 27%), PD (27%, 7%) was observed in Parts B and C respectively. In BRAFi-resistant group, the ORR and PFS with D+T was lower than initial D+T in BRAFi-naive group. Median duration of response (DoR) in BRAFi-resistant group cannot be calculated due to small no. of pts responding. Median DoR for BRAFi-naïve pts was 11.3 mo and 10.5 mo in Parts B and C respectively. In Part C, the 12-mo overall survival rates in BRAFi-naïve (150/2) pts was 79% vs 70% for pts initially on D mono, despite 80% pts crossing over to D+T combination. Conclusions: The clinical activity for 150/2 D+T combination is consistently superior in BRAFi-naive group vs BRAFi-resistant group in both Parts B and C. Dual MAPK blockade can delay clinical resistance to BRAF inhibition. However, once BRAFi resistance has occurred, the combination of BRAFi + MEKi is far less effective. Clinical trial information: NCT01072175. [Table: see text]

8093 Background: Activation of the hepatocyte growth factor (HGF)/MET receptor pathway promotes tumor growth, invasion and dissemination. LY is a humanized IgG4 monoclonal bivalent antibody against MET which inhibits ligand dependent- and ligand independent activation of MET. Based on preclinical results, we examined LY alone in patients with advanced solid tumors and LY+E in advanced NSCLC patients. Methods: LY monotherapy was administered 20-2,000 mg Q2W IV to 23 patients with advanced solid tumors. Combination therapy with 700-2,000 mg Q2W IV of LY and E (150 mg QD) was completed in 14 patients with advanced NSCLC. The primary objective was to determine a recommended phase II dose (RPTD) for LY and LY+E. Secondary objectives included assessment of toxicity, PK, PD (including MET extracelluar domain and HGF), and antitumor activity. Results: LY and LY+E were well tolerated. No dose-limiting toxicities, serious adverse events, or ≥ Grade 3 adverse events (AEs) possibly related to LY have been observed. The most frequent (≥5% of patients) AEs possibly related to LY2875358 monotherapy were nausea (8.7 %), vomiting (8.7%), and diarrhea (8.7%). The most frequent (≥10% of patient) grade 1 or 2 adverse event possibly related to LY2875358 in patients treated with LY+E were fatigue (21.4%) and anorexia (14.3%). Durable PR according to RECIST were observed for LY (n=1) and LY+E (n=2 out of 13 evaluable patients; both PR patients positive for MET protein expression). Conclusions: LY appears to be safe when administered as single agent and in combination with E up to 2,000 mg Q2W IV. The RPTD of LY is 750 mg Q2W IV for monotherapy and in combination with E based on PK/PD data. Clinical trial information: NTC 01287546.

9558 Background: Desmoplastic melanoma (DM) is a rare subtype of melanoma characterized by a dense fibrous stroma, resistance to chemotherapy and no actionable driver mutation for targeted therapy. We investigated the efficacy of PD-1/L1 inhibitors and correlation with genetic landscape and tumor immune microenvironment in DM. Methods: Retrospective analysis of 1054 pts with melanoma treated with anti-PD-1/L1, resulting in 57 pts with unresectable or metastatic DM. Available baseline biopsies were analysed by digital quantitative immunohistochemistry (IHC) for CD8 and PD-L1 and by whole exome sequencing (WES), compared to available tissue from non-DM pts treated with anti-PD1/L1 at UCLA. Results: At a median follow up of 20 mo, 40 pts (70%, 95% CI 57-82) had an objective response by RECIST 1.1 criteria, including 18 (45%) CRs with no relapse observed to date. Responses were similar in DM subsets (23 pure, 29 mixed and 5 indeterminate). Kaplan-Meier estimated 1-year and 2-year overall survival were 85% (95% CI 78-98) and 74% (95% CI 64-89). WES revealed a median of 1282 (interquartile range 517-1692) non-synonymous somatic mutations per tumor in DM tumors (n = 17), significantly higher (p = 0.02) than the median of 462 (interquartile range 230-1150) in non-DM (n = 23). Mutations in NF-1 were the most common (13/17) followed by loss-of-function TP53 and ARID2, and > 82% of single nucleotide mutations were UV damage signatures. IHC analysis from 19 DM and 13 non-DM revealed a strikingly higher percentage of PD-L1 positive cells in the tumor parenchyma in DM (p = 0.04), highly associated with CD8 density and PD-L1 expression in the tumor invasive margins, indicating an active adaptive immune response. No genetic mechanisms known to cause constitutive PD-L1 expression were detected in these samples. Conclusions: Patients with advanced DM derive significant clinical benefit from PD-1/L1 inhibitors, likely related to the high mutational burden and a highly active adaptive immune response as the main mechanism of immune escape prior to therapy. Our results challenge the general conception that dense fibrous stroma around the malignant cells interferes with immune cell infiltration and efficacy of immunotherapy.

Abstract Purpose: The MET/HGF pathway regulates cell proliferation and survival and is dysregulated in multiple tumors. Emibetuzumab (LY2875358) is a bivalent antibody that inhibits HGF-dependent and HGF-independent MET signaling. Here, we report dose escalation results from the first-in-human phase I trial of emibetuzumab. Experimental Design: The study comprised a 3+3 dose escalation for emibetuzumab monotherapy (Part A) and in combination with erlotinib (Part A2). Emibetuzumab was administered i.v. every 2 weeks (Q2W) using a flat dosing scheme. The primary objective was to determine a recommended phase II dose (RPTD) range; secondary endpoints included tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and antitumor activity. Results: Twenty-three patients with solid tumors received emibetuzumab monotherapy at 20, 70, 210, 700, 1,400, and 2,000 mg and 14 non–small cell lung cancer (NSCLC) patients at 700, 1,400, and 2,000 mg in combination with erlotinib 150 mg daily. No dose-limiting toxicities and related serious or ≥ grade 3 adverse events were observed. The most common emibetuzumab-related adverse events included mild diarrhea, nausea, and vomiting, and mild to moderate fatigue, anorexia, and hypocalcemia in combination with erlotinib. Emibetuzumab showed linear PK at doses >210 mg. Three durable partial responses were observed, one for emibetuzumab (700 mg) and two for emibetuzumab + erlotinib (700 mg and 2,000 mg). Both of the responders to emibetuzumab + erlotinib had progressed to prior erlotinib and were positive for MET protein tumor expression. Conclusions: Based on tolerability, PK/PD analysis, and preliminary clinical activity, the RPTD range for emibetuzumab single agent and in combination with erlotinib is 700 to 2,000 mg i.v. Q2W. Clin Cancer Res; 23(8); 1910–9. ©2016 AACR.

Abstract Background: Activation of the hepatocyte growth factor (HGF)/mesenchymal-epithelial transition factor receptor (MET) pathway promotes tumor growth, invasion and dissemination. Emibetuzumab is a humanized IgG4 monoclonal antibody that binds to and inhibits ligand-dependent and ligand-independent activation of MET. In the first-in-human dose escalation study NCT0128756, emibetuzumab demonstrated favorable tolerability when administered up to 2000mg Q2W IV in unselected patients. The study was expanded to evaluate emibetuzumab in expansion cohorts for patients with tumors positive for MET expression. Methods: Patients with locally advanced or metastatic castration-resistant prostate cancer (CRPC) with bone metastasis, renal cell carcinoma (RCC), non-small cell lung cancer (NSCLC), and hepatocellular carcinoma (HCC) received 2000 mg emibetuzumab Q2W IV on a 28-day cycle. RCC, NSCLC, and HCC patients were required to have measurable disease as defined by RECIST v1.1 and have MET positive tumors (≥50% of cells to be ≥2+ for MET expression) as determined by a MET IHC assay (Ventana). The objectives were to evaluate the safety and activity of emibetuzumab in patients with MET positive tumors. Additional objectives included pharmacokinetics (PK) and pharmacodynamics (PD). Results: A total of 62 patients received emibetuzumab across the 4 cohorts: CRPC n = 15, RCC n = 19, NSCLC n = 19,and HCC n = 9, with a median of prior systemic oncology therapies of 6, 3, 5, and 3, respectively. Common possibly related treatment-emergent adverse events included fatigue (29% all grades, 3% Gr3/4), nausea (13% all grades, no Gr3/4), edema of limbs (8% all grades, 2% Gr3/4), and anorexia (8%, no Gr3/4) and were similar among cohorts. No evidence of clinical activity was observed in CRPC patients. For RCC, NSCLC, and HCC patients with MET positive tumors, an overall disease control rate (DCR = partial response [PR] + stable disease [SD]) of 32% (15/47) was observed. In the individual cohorts, DCR was 26% (5/19) in RCC, 26% (5/19) in NSCLC, and 56% (5/9) in HCC. The median duration of disease stabilization in the 3 cohorts was: 4.2 months (range 1.6-24.6) in RCC, 3.9 months (range 2.5-6.4) in NSCLC, and 3.7 months (range 1.2-6.6) in HCC. One PR was observed in an HCC patient with MET amplification. After a single dose of 2000 mg emibetuzumab, PK parameters were similar among these cohorts and also comparable to patients treated at this dose during dose escalation. Conclusions: In cohorts enriched for tumor MET expression, limited single-agent activity of emibetuzumab was observed indicating that MET positivity by IHC (Ventana assay) at the cut-point employed here might not be a sufficient predictive biomarker to select patients receiving benefit from emibetuzumab monotherapy for the tumor types studied. Further evaluation of biomarkers/assays to identify patients who may benefit from treatment with emibetuzumab may be warranted. Citation Format: Michaela S. Banck, Rashmi Chugh, Ronald B. Natale, Alain Algazi, Bradley C. Carthon, Lee S. Rosen, Michael E. Menefee, Andrew Xiuxuan Zhu, Takami Sato, Brian Moser, P. Kellie Turner, Jay Tuttle, Xuejing Aimee Wang, Volker Wacheck, Frederick E. Millard. Phase 1 results of emibetuzumab (LY2875358), a bivalent MET antibody, in patients with advanced castration-resistant prostate cancer, and MET positive renal cell carcinoma, non-small cell lung cancer, and hepatocellular carcinoma. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2015 Nov 5-9; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2015;14(12 Suppl 2):Abstract nr A55.