Effect of FGFR2 alterations on survival in patients receiving systemic chemotherapy for intrahepatic cholangiocarcinoma

303

Background: Most patients (pts) with cholangiocarcinoma (CCA) are diagnosed with advanced disease and are ineligible for surgery. FGFR2 fusions/rearrangements are oncogenic drivers and are present almost exclusively in pts with intrahepatic CCA (iCCA; 10–16% of pts); however, little is known about the effects of FGFR2 status on response to systemic chemotherapy. Memorial Sloan Kettering (MSK) obtains genomic sequencing data from almost all iCCA pts treated at the institution. This provides a unique, rich database from which genomic profiling data can be overlaid with clinical data to facilitate a meaningful understanding of pt outcomes, and to suggest potential therapeutic options. This retrospective analysis evaluated progression free survival (PFS) and overall survival (OS) in pts receiving standard systemic chemotherapy (CXT) for iCCA harboring FGFR2 fusions/rearrangements ( FGFR2 +), or harboring wild-type FGFR2 ( FGFR2wt). Methods: Clinical and genomic data were obtained from the MSK database for all iCCA pts to determine disease history and exposure to prior lines (PL) of CXT in the advanced setting. Only pts with complete data for PL of CXT were analyzed. Median PFS and OS were calculated using the Kaplan-Meier method. OS was calculated from diagnosis until death; PFS was calculated from first dose of first line of CXT until progression, death, last visit, relevant dates of later CXT lines; pts with unconfirmed outcomes were censored at last known follow-up date. Results: One-hundred-thirty-two pts were included in this analysis (median age at diagnosis: 62.0 y; 54.5% female; FGFR2+, n = 15; FGFR2wt, n = 115; other FGFR2 alterations, n = 2). Among pts receiving first-line CXT, median PFS was 7.1 months (95% CI: 5.0–8.3) for all pts (n = 124), 6.2 months (2.0–16.8) for FGFR2+ pts (n = 15), and 7.2 months (5.0–8.3) for FGFR2wt pts (n = 107). Among pts with ≥2 PL of CXT (n = 90), median PFS on second-line chemotherapy was 5.6 months (95% CI: 2.8–10.3) for FGFR2+ pts, and 3.7 months (2.6–5.6) for FGFR2wt pts. Median OS was numerically longer in FGFR2+ pts compared with FGFR2wt pts (31.3 months [95% CI: 5.8–not estimable] vs 21.8 months [16.7–26.6]). Conclusions: Among pts receiving standard systemic chemotherapy for iCCA, median PFS was similar in pts harboring FGFR2+ vs FGFR2wt receiving first-line chemotherapy, and relatively longer in pts harboring FGFR2+ receiving second-line chemotherapy. Median OS was longer in FGFR2+ vs FGFR2wt pts. Compared with recently published data in molecularly unselected CCA pts (Lowery. Cancer. 2019; 125: 4426), PFS was similar in pts receiving first-line chemotherapy, and slightly longer for second-line chemotherapy. Data interpretation is limited by the retrospective nature of this analysis of investigator-reported data, the study size, and by the possibility that the analysis population may not reflect the general population of pts with CCA.

Pembrolizumab with trastuzumab and chemotherapy (PTC) in HER2-positive metastatic esophagogastric cancer (mEG): Plasma and tumor-based biomarker analysis

4559

Background: Pembrolizumab can be safely combined with trastuzumab and chemotherapy and has promising activity with median OS 27 months and 91% objective response rate in HER2-positive mEG cancer irrespective of PD-L1 status (NCT02954536; Janjigian ESMO 2019). Tumor biopsies and blood samples were collected in this phase II trial to identify molecular and immune predictors of response and resistance to PTC. Methods: Pre-treatment and post-progression biopsies were analyzed using WES and IHC (HER2, PD-L1). Peripheral blood was collected pre-treatment, every 9 weeks on-treatment and at progression for plasma ctDNA (Guardant 360, Guardant Health, Redwood, CA). Tumor-matched DNA alterations were identified by correlating ctDNA and solid tumor WES results. Landmark PFS analysis was used to compare ctDNA clearance status at 9 weeks post-treatment. Results: Baseline ctDNA was analysed from 31 of 37 patients of whom 84% (26/31) had tumor-matched ctDNA detected at baseline. Patients who cleared ctDNA at 9 weeks (n = 17/23) achieved a longer median PFS than those who did not - mPFS 12.3 months (95% CI 7.44-NA vs 3.9 months (95% CI 2.01-NA) (log-rank p = 0.02). On serial blood monitoring of 16 patients with eventual radiographic progression, ctDNA re-appearance preceded CT detection in 8 (50%) patients. WES was completed in 31 patients with pre-treatment, and 12 patients post-progression, including matched samples from 10 patients. Loss of HER2 over-expression/amplification was noted in 44% (7/16) of post-progression samples by IHC/FISH (2 IHC 0/1, 5 FISH-). In paired post-progression samples on WES, we observed loss of ERBB2 in 2 patients, and new amplifications of CCND1/3, FGF3/4/19, CDK6/12, KRAS, MYC, and MET, as well as mutations in KRAS, PIK3CD and PIK3RA. Plasma analysis at progression demonstrated copy number increases and/or new amplifications in MET, CKD6, PIK3CA, KRAS, FGFR2, EGFR and CCDN1 as well as KRAS, RB1, PTEN, NF1, NOTCH1, BRAF, and FGFR1 mutations. Conclusions: The majority of patients with previously untreated HER2 positive mEG have detectable plasma ctDNA at baseline. The re-appearance of ctDNA during therapy may serve as an early predictor of progression and help identify genetic drivers of acquired resistance. Loss of ERBB2 over-expression/amplification and activating MAPK alterations occur at PTC progression. Evaluation of tumor immune environment by multiplex IHC and additional ctDNA analysis is underway.

Actionable alterations (AA) in gastrointestinal (GI) cancers: Rate of detection and receipt of matched therapies (MT)

e15677

Background: Next generation sequencing (NGS) is widely used in pts with advanced cancer to personalize care. Current NCCN guidelines endorse Her2, PD-L1 and MSI testing in esophagogastric cancer (EGC), RAS, BRAF, Her2 and MSI testing in colorectal cancer (CRC) and germline, somatic and MSI testing in pancreas cancer (PC). The proportion of GI cancer pts who receive MT based on NGS is unclear. Methods: We identified pts with advanced EGC (2016-18), PC (2017) and CRC (2016) who underwent NGS with MSK-IMPACT. We assessed the proportion of pts with ≥1 AA as defined by OncoKB (at the time of analysis, levels 1/2a were accepted practice and levels 2b/3/4 were investigational; Chakravaty, JCO PO 2017), those who received MT on trial or off label and 3 and 6 months (mos) progression-free survival (PFS). Results: We identified 260 EGC, 357 PC and 438 CRC pts. After excluding pts who had ongoing benefit from standard therapy (tx), were treated elsewhere or had no active stage IV disease, potential level 2/3/4 AAs occurred in 37% (n = 97) of EGC pts, 32.5% (n = 116) of PC pts and 26.7% (n = 117) of CRC pts (Table). 10, 1 and 17 pts with EGC, PC and CRC respectively were MSI. 1 pt in each subtype had an NTRK fusion (OncoKB level 1). In EGC, 6 pts (6.2% of those with AAs) received MT: 2 pts with MET amplification (a) and 1 each with BRCA2 mutation (m), TSC2m, ERBB2m and EGFRa. The pts with METa treated with crizotinib achieved 3 but not 6 mos PFS. In PC, 11 pts (9.5%) got MT: 10 pts for BRCAm and 1 for NTRK3 fusion. 9 pts with BRCAm treated with PARP inhibitors (i) achieved ≥3 mos PFS and 5 pts reached ≥6 mos PFS. The pt treated with NTRKi progressed rapidly. In CRC, 5 pts with ERBB2a and 9 pts with BRAFm received MT (12%). 3 pts and 2 pts treated with anti-Her2 tx achieved ≥3 and ≥6 mos PFS respectively. Of 6 pts treated with BRAF/MEKi plus irinotecan or anti-EGFR tx, all achieved ≥3 mos PFS; 3 reached ≥6 mos PFS. 3 pts received novel BRAF and ERK1/2i; none reached 3 mos PFS. Conclusions: NGS frequently identified OncoKB level 2 AAs. Few pts received MT, and of those, some achieved ≥6 mos PFS. Pts with CRC and PC received MT which subsequently became standard NCCN recommendations; therefore, a more current analysis may show increased MT use. Still, MT for level 3 and 4 alterations were rare, suggesting expectations of NGS must be managed appropriately. [Table: see text]

A phase II study of ADI-PEG 20 and FOLFOX6 in patients (pts) with advanced hepatocellular carcinoma (HCC)

TPS477

Background: Arginine depletion interferes with pyrimidine metabolism as well as DNA damage repair pathways, and preclinical data indicate that pairing pegylated arginine deiminase (ADI-PEG 20) with fluoropyrimidines or platinum enhances cytotoxicity in vitro and in vivo in HCC models. A prior phase 1 study of FOLFOX6 and ADI-PEG 20 established the safety and recommended phase 2 dose of the combination in pts with advanced gastrointestinal tumors (Harding et al. CCP 2018). For 23 treatment-refractory HCC pts who were treated at the recommended phase 2 dose on an expansion cohort of the phase 1, the objective response rate (ORR) was 21% (95% CI 7.5-43.7) and median progression-free survival (PFS) was 7.3 months. These data were favorable when compared to historic data for FOLFOX alone where the ORR was ~8% and PFS was 2.93 months and suggest greater clinical activity of the combination (Qin et al. JCO 2013). Prospective confirmation of these results is required. Methods: This is an international, multicenter, single-arm, open-label phase 2 trial of ADI-PEG 20 and FOLFOX6 for advanced HCC pts with Child-Pugh A liver function who progressed on ≥ 2 prior lines of prior systemic therapy (NCT02102022). The primary objective is to define the ORR by RECIST 1.1 as assessed by blinded independent central review. Secondary objectives include determination of safety, disease control rate (DCR), duration of response (DOR), PFS, overall survival (OS), serum arginine, citrulline and anti-ADI-PEG 20 levels over 24 weeks, and alpha-fetoprotein response. Eligible pts receive intravenous FOLFOX6 biweekly at standard doses and ADI-PEG 20 intramuscularly weekly at 36 mg/m.2 Cross-sectional imaging will be completed every 8 weeks until progression of disease. Based on a two-sided exact test of a one-sample proportion with an alpha of 0.05, under a presumed ORR of 22%, there is 80% power to yield 95% confidence interval of 15-26%, which will require 46 objective responses in 225 subjects. Futility will be assessed three times during the study based on having ORR data available for 56, 110, and 166 patients. This Phase 2 will be stopped for futility if the conditional power drops below 20% at any of these time points. Clinical trial information: NCT02102022.

First-line pembrolizumab (P), trastuzumab (T), capecitabine (C) and oxaliplatin (O) in HER2-positive metastatic esophagogastric adenocarcinoma (mEGA)

62

Background: Trastuzumab stimulates HER2-specific T cell responses and increases tumor PD-L1 expression, and anti-PD-1 antibody can help enhance T cell-specific immunity of trastuzumab. Oxaliplatin can further enhance T-cells by activating dendritic cells. We conducted a phase II trial of pembrolizumab with chemotherapy/trastuzumab. Methods: Patients with previously untreated HER2 IHC 3+ or FISH+ tumors irrespective of PD-L1 status received intravenous P 200 mg flat dose, T 6 mg/kg (after 8 mg/kg load), O 130 mg/m2 every 3 weeks and oral C 850 mg/m2 2 weeks on/1 week off (or 5-FU continuous infusion). The primary endpoint was 6-months PFS; with target accrual of 37 patients. Secondary endpoints included safety, OS, ORR, exploratory biomarker analysis and 89Zr-trastuzumab PET. Results: 100% of the 24 evaluable pts had tumor regression (ranging from -22% to -100%). The RECIST 1.1 ORR was 83% [95%CI: 63%-95%] (17 PR , 3 CRs), median PFS 11.4 [95%CI: 6-15] months. In 31 pts evaluable for toxicity, common ( > 10%) adverse events included Gr 2 fatigue (35%), Gr 2/3 nausea (35%), Gr 2 diarrhea (26%), Gr2 AST/ALT elevation (16%), Gr2 neutropenia (16%). Immune related toxicities observed in 1 pt each: Gr 2 colitis, Gr 3 interstitial nephritis, Gr 3 AST/ALT elevation; and resolved with steroids. Of 21 patients with available material, 6 (29%) expressed PD-L1. Of these 6 patients, 5 had a PR while 1 had a CR. ERBB2 amplification was evident on NGS in 56% of pre-treatment tumors from 25 tested patients, while the remaining were ERBB2- by NGS likely due to tumor heterogeneity or low tumor content. Mutations in TP53 and alterations in KRAS occurred in 68% and 16%, respectively. To identify mechanisms of acquired resistance, patients are biopsied at progression. In 6 paired sample analysis, we identified two patients with loss of ERBB2 amp at progression. Conclusions: Updated survival, correlative studies and 89Zr-trastuzumab PET imaging will be presented. These promising preliminary safety and efficacy results led to initiation of a definitive phase III Keynote 811 trial. Clinical trial information: NCT02954536.