Citations

9506 Background: Survival is poor in mUM and treatment options are limited. MET kinase is over-expressed on UM and the MET inhibitor cabo showed activity in an early trial. Methods: A091201 was a 2:1 randomized phase II study testing progression-free survival (PFS) of cabo (60 mg daily) vs chemo (DTIC/TMZ). We studied baseline metastatic tumor samples (n = 19; 1 lung, 18 liver) by whole exome sequencing (WES) and RNAseq. We correlated data with OS and made comparisons for mUM vs. primary tumors from TCGA (n = 80). Results: 46 patients were accrued with 96% and 63% with liver metastases and elevated LDH, respectively. Toxicities were similar to prior reports of cabo and chemo. The trial stopped at interim analysis due to no difference in PFS (p = 0.964; HR = 0.99) or OS (p = 0.580; HR = 1.21). WES showed tumor mutational burden of 46±4 (mean±SEM) and did not separate OS at 1 year (p = 0.14, two-sided Wilcoxon rank sum test) in A091201. Recurrent known mutations included GNAQ/11, SF3B1, BAP1; novel mutations included GOLGA6L10, PKD1L3, and FAM228B. Gene expression signatures differed significantly between A091201 and TCGA cohorts including MET signaling (p = 7.87e-22), T cell-inflamed (p = 0.004), homologous recombination deficiency (p = 0.004), proliferation (p = 0.009) and hypoxia (p = 5.2e-10) (two-sided Student’s t-test). Tumor immune cell enrichment analysis revealed significant differences with lower M1:M2 macrophage (p = 1.2e-10) and higher Tregs (p = 6.0E-21) in mUM relative to TCGA (two-sided Wilcoxon rank sum test). Epithelial-mesenchymal transition gene expression signature was significantly associated with worse OS in A091201 (p = 0.02) with angiogenesis signature trending toward significance (p = 0.21) (log-rank test). OS separated by differentially expressed genes with OS ≤ 1 year associating with increased expression of the angiogenesis/immune-associated molecule neuropilin 1. Conclusions: These results provide insights between primary and mUM indicating potential novel therapeutic approaches. Support: U10CA180821, U10CA180882, T32GM007019, Exelixis. https://acknowledgments.alliancefound.org ; Clinical trial information: NCT01835145.

6020 Background: A subset of salivary gland cancer (SGCs) express the androgen receptor (AR). This phase II trial evaluated the anti-androgen enzalumatide (Astellas) for patients with AR+ SGCs. Methods: Locally advanced/unresectable or metastatic AR+ SGCs were enrolled (AR status was centrally confirmed). Prior therapy with AR-targeted drugs was allowed. Enzalutamide 160 mg orally once daily was given (1 cycle= 28 days). The primary endpoint was confirmed response (RR) according to RECIST v1.1 within the first 8 cycles. Secondary endpoints were progression-free survival (PFS), overall survival (OS), and safety. A Simon-Optimal two-stage design was used to detect a 20% RR (vs. 5%) (alpha = 5%; beta = 90%). > 1 response(s) in the first 21 would trigger accrual to 41; > 4 responses would be considered promising. Results: 46 eligible patients (pts) were enrolled (40 M, 6 F; median age 65) in 22 months. In the first 21 pts, we initially had 2 confirmed PRs allowing for full study accrual, though one was later changed to stable disease. Among the 46 pts, 7 had PR as best response, though only 2 were confirmed within the first 8 cycles (4% (95% CI: 0.5-15%). Two other PRs did not count towards the primary endpoint due to 1) development beyond 8 cycles (cycles 12-18) and 2) a confirmatory scan completed <4 weeks apart. The other 3 pts with unconfirmed PR developed progression of disease (PD) after the first PR scan. 24 pts had stable disease; 15 pts PD as best response. Among 11 pts previously treated with AR-targeted therapy, best responses were 1 confirmed PR, 7 SD, 3 PD. With a median follow-up of 11.7 months (mo), OS at 12 mo was 66% (95% CI: 52-83%), PFS at 12 mo was 24% (95% CI: 14-42%), and median PFS was 5.5 mo (95% CI: 3.7-7.3). Conclusions: This is the first prospective trial evaluating an antiandrogen alone for AR+ SGCs. The failure to meet the protocol-defined measure of success was due in part to the lack of durability of initial responses. The clinical activity observed suggests the AR-dependence of AR+ SGCs, even among those previously treated with other hormonal therapies. Support: U10CA180821, U10CA180882; Astellas; https://acknowledgments.alliancefound.org. Clinical trial information: NCT02749903.

5029 Background: Pembro had activity as monotherapy in pretreated advanced mCRPC. Data are presented here from cohort B (pembro + docetaxel/prednisone) of KEYNOTE-365 (NCT02861573), a phase 1b/2 umbrella study to test combinations in mCRPC. Methods: Pts who progressed on or became intolerant to ≥4 wk of abi or enza in the prechemotherapy mCRPC state and progressed within 6 mo before screening were eligible. Pts received pembro 200 mg IV with docetaxel 75 mg/m2 IV Q3W plus prednisone 5 mg orally twice daily. The primary end points were safety and PSA response rate (confirmed PSA decrease ≥50%). Key secondary end points were investigator-determined ORR (RECIST v1.1), disease control rate (DCR: CR+PR+SD ≥6 mo), time to PSA progression, rPFS, and OS. Results: 72 pts (median age, 68 y; visceral disease, 36%; measurable disease, 50%) began pembro + docetaxel. Median (95% CI) follow-up was 10 (8-12) mo. Efficacy is outlined in the table. Treatment-related AEs occurred in 69 (96%) pts; most frequent (≥30%) were alopecia (43%), fatigue (40%), and diarrhea (39%). Grade 3-5 treatment-related AEs occurred in 27 (38%) pts, including 2 deaths from treatment-related AEs (pneumonitis). Most commonly reported immune-mediated AEs were infusion-related reactions (11%) and colitis (10%). Conclusions: Pembro + docetaxel/prednisone has activity in pts with mCRPC who previously progressed on second-generation hormone therapy. AEs were considered mild for the treatment combination. Clinical trial information: NCT02861573. [Table: see text]

e12003 Background: Irinotecan liposome injection (nal-IRI) uses intraliposomal stabilisation technology to enable high drug load and in-vivo stability. This analysis characterizes the PK profile of nal-IRI in pts with mBC. Methods: The expansion of NCT01770353 enrolled 30 pts with mBC over three cohorts (Cohort 1: ER+ and/or PR+ BC [C-1]; Cohort 2: Triple Negative BC [C-2]; and Cohort 3: BC with active Brain Metastasis [C-3]). Key inclusion criteria: ECOG ≤1; adequate organ function; and >1 and ≤5 prior lines of cytotoxic therapy in metastatic setting. Most pts received nal-IRI 60 mg/m2 salt-based equivalent (50 mg/m2 free base equivalent [FBE]) or 80 mg/m2 (70 mg/m2 FBE) q2w by iv infusion, based on tolerance; 2 pts were treated at 40 mg/m2 (35 mg/m2 FBE). Plasma samples were collected over 360h across cycles 1, 2 &3, and analysed using LC-MS/MS for total irinotecan. Data were analysed by a non-compartmental approach using Phoenix Winnonlin, and were compared with values from studies in other tumor types. Results: 21 patients were evaluable for PK analysis (C-1, n=6; C-2, n=7; and C-3, n=8). No trend for accumulation was observed in cycle 2 or 3, when comparing total irinotecan Cmax & exposure (area under the curve at 168 h [AUC168]) versus cycle 1. At 40-80 mg/m2 (35-70 mg/m2 FBE), Cmax of irinotecan tended to increase proportionally with total dose, and was comparable to studies in other tumour types (see Table). Among 29 pts who received nal-IRI, partial response (per RECIST) was observed in 10 pts. The most related TEAEs (≥ 25%) were diarrhea, nausea, vomiting, hypokalaemia, decreased appetite and fatigue. Stable disease was observed in 5 pts. Conclusions: PK parameters in patients with mBC were comparable to historical studies in patients with other tumour types. The safety profile of nal-IRI monotherapy appeared consistent with gastrointestinal and blood disorders. [Table: see text]

Abstract Background: Estrogen receptor (ER)-negative tumors and human epidermal growth factor 2-Neu (HER2) positive breast cancers are known to be more clinically aggressive subtypes of breast cancer and account for 30% of all breast cancers. Women with HER2 + breast cancers, whether ER+ or ER -, require cytotoxic chemotherapy with a HER2-targeting agent, and often have adverse outcomes. Thus, preventive agents are needed to reduce the incidence of these subtypes of aggressive breast cancer. Lapatinib, a dual tyrosine kinase inhibitor, inhibits epidermal growth factor receptors (EGFR) and HER2 kinases and has shown to decrease breast cell proliferation in invasive breast cancer and adjacent premalignant lesions. Therefore, we conducted a multi-institutional randomized Phase II clinical trial to study the effects of the signal transduction inhibitor lapatinib in women with HER2-positive or EGFR-positive ductal carcinoma in situ (DCIS). Methods: Randomized participants received either lapatinib (750mg, 1000mg, or 1500mg) or placebo daily for 2-6 weeks prior to their surgery. After minimal accrual, the trial was later amended to lapatinib 1000mg or placebo. Pre-treatment breast tissue was obtained from initial diagnostic core biopsy and post-treatment breast tissue was obtained from surgical excision specimen. Blood was obtained prior to surgery to assess serum lapatinib level. Participants kept a daily symptom assessment log and had a cardiac assessment at baseline and prior to surgery. Patients were instructed to take drug up to and including the day before surgery. The dual primary endpoint for this study was change in proliferation in pre- versus post-treatment biopsies between the two treatment arms, as measured by Ki67 as well as toxicity assessment. Secondary endpoints included incidence of DCIS at surgery and modulation of tissue biomarker expression in growth factor receptors (EGFR, ErbB2); phosphorylated growth factor receptor (phospho-ErbB2); signal transduction markers (MAPK, phospho-MAPK); hormone receptors (ER, PR); and p27. Results:Twenty-two women (mean age: 51; range: 32-66) with HER2+ or EGFR+ DCIS were treated with lapatinib (1,000 or 1,500 mg) or placebo for 2–6 weeks prior to surgical excision. Ki67 expression was significantly decreased in the lapatinib treatment arms compared to placebo (p=0.0122). Diarrhea, fatigue, and skin reactions were notable adverse events that occurred predominately in the lapatinib arm compared to placebo. No grade 3 or 4 events related to the study drug were noted during the study. No changes were noted in cardiac function. DCIS was present in all surgical specimens in both arms. Invasive breast cancer was noted in 1 patient on lapatinib 1000mg and 3 patients on placebo. No statistically significant changes were noted in signal transduction biomarkers Conclusion:These results demonstrate the effectiveness of lapatinib in reducing proliferation in women with EGFR+ or HER2+ DCIS. Even low-grade toxicities can deter use of an agent in the prevention setting. This and the lack of a risk model for HER2+ and triple negative breast cancer make the development of larger scale clinical prevention trials of lapatinib for the prevention a challenge. Citation Format: Thomas PS, Contreras A, Pruthi S, Krontiras H, Rimawi M, Garber J, Wang T, Hilsenbeck SG, Vornik LA, Gilmer T, Friedman R, Heckman-Stoddard BM, Dunn B, Kuerer H, Brown PH. A phase II pre-surgical trial of lapatinib for the treatment of women with HER2 positive or EGFR positive ductal carcinoma in situ [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr PD3-07.