Circulating Tumor DNA as a Predictive Biomarker for Clinical Outcomes With Margetuximab and Pembrolizumab in Pretreated HER2-Positive Gastric/ Gastroesophageal Adenocarcinoma.

PURPOSE: To assess the ability of circulating tumor DNA (ctDNA)-based testing to identify patients with HER2 (encoded by ERBB2)-positive gastric/gastroesophageal adenocarcinoma (GEA) who progressed on or after trastuzumab-containing treatments were treated with combination therapy of anti-HER2 and anti-PD-1 agents. METHODS: ctDNA analysis was performed retrospectively using plasma samples collected at study entry from 86 patients participating in the phase 1/2 CP-MGAH22-05 study (NCT02689284). RESULTS: Objective response rate (ORR) was significantly higher in evaluable ERBB2 amplification-positive vs - negative patients based on ctDNA analysis at study entry (37% vs 6%, respectively; P = .00094). ORR was 23% across all patients who were evaluable for response. ERBB2 amplification was detected at study entry in 57% of patients (all HER2 positive at diagnosis), and detection was higher (88%) when HER2 status was determined by immunohistochemistry fewer than 6 months before study entry. ctDNA was detected in 98% (84/86) of patients tested at study entry. Codetected ERBB2-activating mutations were not associated with response. CONCLUSIONS: Current ERBB2 status may be more effective than archival status at predicting clinical benefit from margetuximab plus pembrolizumab therapy. ctDNA testing for ERBB2 status prior to treatment will spare patients from repeat tissue biopsies, which may be reserved for reflex testing when ctDNA is not detected.

Bemarituzumab in patients with FGFR2b-selected gastric or gastro-oesophageal junction adenocarcinoma (FIGHT): a randomised, double-blind, placebo-controlled, phase 2 study.

BACKGROUND: Outcomes are poor in patients with HER2-negative, advanced gastric or gastro-oesophageal junction adenocarcinomas. In this study, we investigated efficacy and safety of the first-in-class, afucosylated, humanised IgG1 anti-fibroblast growth factor receptor 2 isoform IIb (FGFR2b) monoclonal antibody bemarituzumab with modified 5-fluorouracil, leucovorin, and oxaliplatin (mFOLFOX6) in patients with FGFR2b-selected gastric or gastro-oesophageal junction adenocarcinoma. METHODS: In the randomised, double-blind, placebo-controlled phase 2 trial (FIGHT), patients aged 18 years and older with HER2 non-positive, FGFR2b-selected gastric or gastro-oesophageal junction adenocarcinoma, and an Eastern Cooperative Oncology Group performance status of 0-1 were recruited from 144 clinical sites across 17 countries. Patients with previous treatment with any selective inhibitor of the FGF-FGFR pathway were excluded. Eligible patients were randomly assigned (1:1), using permuted-block randomisation (block size of four) and a central interactive voice-web-based response system, stratified by geographical region, previous treatment with curative intent, and administration of mFOLFOX6 while being screened for FGFR2b status, to either bemarituzumab (15 mg/kg of bodyweight) or matched placebo intravenously every 2 weeks. All patients also received mFOLFOX6 (oxaliplatin 85 mg/m2, leucovorin 400 mg/m2, and 5-fluorouracil as a 400 mg/m2 bolus followed by 2400 mg/m2 over approximately 46 h) intravenously every 2 weeks. Patients were given treatment until disease progression (defined by Response Evaluation Criteria in Solid Tumours [RECIST] version 1.1), unacceptable toxicity, withdrawal of consent, or death. The primary endpoint was progression-free survival in the intention-to-treat population (defined as all patients randomly assigned to treatment). Safety was assessed in all patients who received at least one dose of assigned treatment. This study is registered with ClinicalTrials.gov, NCT03694522, and is now complete. FINDINGS: Between Nov 14, 2017, and May 8, 2020, 910 patients were screened and 155 were randomly assigned to the bemarituzumab (n=77) or placebo group (n=78). Median age was 60·0 years (IQR 51·0-67·0), 44 (28%) participants were women, 111 (72%) were men, 89 (57%) were Asian, and 61 (39%) were White. At the time of the primary analysis and at a median follow-up of 10·9 months (IQR 6·3-14·2), median progression-free survival was 9·5 months (95% CI 7·3-12·9) in the bemarituzumab group and 7·4 months (5·8-8·4) in the placebo group (hazard ratio [HR] 0·68 [95% CI 0·44-1·04; p=0·073). Common grade 3 or worse adverse events were decreased neutrophil count (23 [30%] of 76 in the bemarituzumab group vs 27 [35%] of 77 in the placebo group), cornea disorder (18 [24%] vs none), neutropenia (ten [13%] vs seven [9%]), stomatitis (seven [9%] vs one [1%]), and anaemia (six [8%] vs ten [13%]). Serious treatment-emergent adverse events were reported in 24 (32%) patients in the bemarituzumab group and 28 (36%) in the placebo group. Serious mFOLFOX6 treatment-related adverse events occurred in nine (12%) patients in the bemarituzumab group and in 15 (19%) patients in the placebo group. All-grade corneal events (adverse events of special interest) occurred in 51 (67%) patients in the bemarituzumab group and eight (10%) in the placebo group; grade 3 corneal events were reported only in 18 (24%) patients in the bemarituzumab group. Treatment-related deaths occurred in three patients in the bemarituzumab group (two due to sepsis, one due to pneumonia) and none in the placebo group. INTERPRETATION: In this exploratory phase 2 study, despite no statistically significant improvement in progression-free survival, treatment with bemarituzumab showed promising clinical efficacy. Confirmatory phase 3 trials of bemarituzumab plus mFOLFOX6 powered to demonstrate statistical significance are being investigated in patients with previously untreated, FGFR2b-overexpressing, advanced gastric or gastro-oesophageal junction adenocarcinoma. FUNDING: Five Prime Therapeutics.

Epacadostat Plus Pembrolizumab and Chemotherapy for Advanced Solid Tumors: Results from the Phase I/II ECHO-207/KEYNOTE-723 Study.

BACKGROUND: Epacadostat, an oral, selective inhibitor of IDO1, has shown activity when administered with pembrolizumab. We evaluated the addition of chemotherapy to epacadostat and pembrolizumab in patients with advanced or metastatic solid tumors. One proposed mechanism of resistance to PD-1 checkpoint inhibition is through immunosuppression mediated by L-kynurenine. IDO1, indoleamine-2,3-dioxygenase 1 is the rate-limiting enzyme catalyzing the conversion of L-tryptophan to L-kynurenine. If IDO1 is a mechanism of tumor escape from checkpoint inhibition, then addition of an IDO1 inhibitor with a PD-1 checkpoint inhibitor could enable tumor response to immunotherapy. METHODS: Patients received one of 7 tumor-appropriate chemotherapy regimens. Pembrolizumab 200 mg was infused intravenously every 3 weeks. Epacadostat 100 mg was administered orally twice daily. The primary objectives of phase I were determining safety/tolerability and defining the maximum tolerated or pharmacologically active dose of epacadostat. Phase II of the study was designed to enroll efficacy-expansion cohorts and to assess changes in the tumor and tumor microenvironment via mandatory-biopsy cohorts. RESULTS: A total of 70 patients were enrolled. Twelve patients were enrolled in the phase II mandatory-biopsy cohorts. Due to early study closure, efficacy expansion did not enroll. Grades 3 and 4 treatment-emergent adverse events (TEAEs) occurred in 78.6% of patients. Neutropenia and disease progression were the only grades 3 and 4 TEAEs reported in ≥10.0% of patients. One treatment-related death was reported. The ORR was 31.4% across all treatment groups. CONCLUSION: The combination of epacadostat 100 mg bid with pembrolizumab and chemotherapy had an acceptable safety profile. This regimen showed antitumor activity across multiple types of advanced or metastatic solid tumors (ClinicalTrials.gov Identifier: NCT03085914).

Phase II Prospective, Open-Label Randomized Controlled Trial Comparing Standard of Care Chemotherapy With and Without Sequential Cytoreductive Interventions for Patients with Oligometastatic Foregut Adenocarcinoma and Undetectable Circulating Tumor Deoxyribose Nucleic Acid (ctDNA) Levels.

BACKGROUND: Metastatic adenocarcinomas of foregut origin are aggressive and have limited treatment options, poor quality of life, and a dismal prognosis. A subset of such patients with limited metastatic disease might have favorable outcomes with locoregional metastasis-directed therapies. This study investigates the role of sequential cytoreductive interventions in addition to the standard of care chemotherapy in patients with oligometastatic foregut adenocarcinoma. METHODS: This is a single-center, phase II, open-label randomized clinical trial. Eligible patients include adults with synchronous or metachronous oligometastatic (metastasis limited to two sites and amenable for curative/ablative treatment) adenocarcinoma of the foregut without progression after induction chemotherapy and having undetectable ctDNA. These patients will undergo induction chemotherapy and will then be randomized (1:1) to either sequential curative intervention followed by maintenance chemotherapy versus routine continued chemotherapy. The primary endpoint is progression-free survival (PFS), and a total of 48 patients will be enrolled to detect an improvement in the median PFS in the intervention arm with a hazard ratio (HR) of 0.5 with 80% power and a one-sided alpha of 0.1. Secondary endpoints include disease-free survival (DFS) in the intervention arm, overall survival (OS), ctDNA conversion rate pre/post-induction chemotherapy, ctDNA PFS, PFS2, adverse events, quality of life, and financial toxicity. DISCUSSION: This is the first randomized study that aims to prospectively evaluate the efficacy and safety of surgical/ablative interventions in patients with ctDNA-negative oligometastatic adenocarcinoma of foregut origin post-induction chemotherapy. The results from this study will likely develop pertinent, timely, and relevant knowledge in oncology.

Morphologic and molecular analysis of early-onset gastric cancer.

BACKGROUND: Evidence suggests that early-onset gastric cancers are distinct from traditional gastric cancers; however, detailed genomic and morphologic characterization of these cancers has not been performed. METHODS: Genomic analysis was performed for 81 patients with gastric cancer who were 50 years old or younger; pathology slides were available for 53 of these patients, and they were re-reviewed to perform a morphologic-molecular correlation analysis. The results were compared with corresponding cBioPortal data and The Cancer Genome Atlas (TCGA) analysis, which represent traditional gastric cancers. The TP53 molecular signature was established to determine the pattern of somatic mutational damage. Variants of potential germline origin were also identified from next-generation sequencing data. RESULTS: A higher rate of CDH1 mutations (22.2% of early-onset gastric cancers vs 11.4% of traditional gastric cancers; P = .0042) but a similar rate of TP53 mutations (63% of early-onset gastric cancers vs 56.6% of traditional gastric cancers; P = .2674) were seen in early-onset cancers in comparison with traditional gastric cancers. The diffuse/mixed types correlated with the TCGA genomically stable type, and the remaining Lauren types correlated with the TCGA chromosomal instability type. Diffuse and indeterminate histologic types (overall survival, 26.25 months for the intestinal type, 20.5 months for the mixed type, 12.62 months for the diffuse type, and 9 months for the indeterminate type; P = .027) and the presence of a CDH1 gene mutation (overall survival, 9 months for mutant CDH1 and 22 months for wild-type CDH1; P = .013) significantly correlated with worse survival. The TP53 gene frequently showed transition mutations (65.5%) involving the CpG sites (49%). Variants of potential germline origin were seen in high-penetrance genes (CDH1 and APC) and moderate-penetrance genes (ATM, NBN, and MUTYH) in 9.9% of cancers. CONCLUSIONS: Early-onset gastric cancer has distinct genomic alterations, such as CDH1 mutations, but shares with traditional gastric cancers a high frequency of TP53 mutations and the TP53 mutagenic signature. Diffuse and indeterminate histologic types and the presence of a CDH1 mutation are associated with worse overall survival. Endogenous factors leading to cytosine deamination and potential germline alterations in moderate-penetrance cancer susceptibility genes may be implicated in the pathogenesis of these cancers.

Toward a Treatment Sequencing Strategy: A Systematic Review of Treatment Regimens in Advanced Gastric Cancer/Gastroesophageal Junction Adenocarcinoma.

BACKGROUND: Platinum and fluoropyrimidine combinations typically comprise first-line (1L) therapy in advanced gastric cancer or gastroesophageal junction adenocarcinoma (G/GEA), although controversy exists regarding the use of 5doublet versus triplet cytotoxic regimens. Historically, second-line (2L) and third-line or later (3L+) therapy has been fragmented. Recent trials have increased the need for optimal treatment sequencing in advanced G/GEA. MATERIALS AND METHODS: We conducted a systematic search of peer-reviewed manuscripts of randomized clinical trials examining 1L, 2L, and 3L+ therapy for advanced G/GEA published from 2009 through November 19, 2019. When available, overall survival, progression-free survival, time to progression, overall response rate, and toxicity were extracted from each and compared descriptively. RESULTS: In 1L therapy, chemotherapy triplets demonstrated variable efficacy improvements with invariable increased toxicity compared with platinum/fluoropyrimidine doublets. Currently, the only published report of positive outcomes using biologics in 1L describes adding trastuzumab in HER2-overexpressing advanced G/GEA. In 2L, doublet chemotherapy regimens are not uniformly more efficacious than single-agent taxanes or irinotecan, and ramucirumab has demonstrated improved outcomes both as monotherapy and in combination. CONCLUSION: For advanced G/GEA, review of trial results from 2009-2019 support 1L therapy with platinum and fluoropyrimidine and sequencing with taxanes or irinotecan in combination with biologics as effective 2L options. Escalating to a triplet may add some efficacy at the expense of added toxicity. IMPLICATIONS FOR PRACTICE: The rapidly changing treatment landscape for advanced gastric cancer includes increasing options for refractory disease. With multiple first-line platinum-based regimens, identification of those with the best benefit-to-risk ratio may provide guidance on treatment sequencing strategies. This article presents findings from the published literature of randomized controlled trials that included a first-line platinum/fluoropyrimidine combination and, for second-line trials, patients with platinum/fluoropyrimidine-refractory disease. This guiding summary could be a tool for clinicians to identify the optimal first-line regimen(s) followed by a strategy for subsequent regimens.

Cytoreductive Surgery for Selected Patients Whose Metastatic Gastric Cancer was Treated with Systemic Chemotherapy.

BACKGROUND: The authors hypothesized that cytoreductive surgery (CRS, comprising gastrectomy combined with metastasectomy) in addition to systemic chemotherapy (SC) is associated with a better survival than chemotherapy alone for patients with metastatic gastric adenocarcinoma (MGA). METHODS: Patients with MGA who received SC between 2004 and 2016 were identified using the National Cancer Database (NCDB). Nearest-neighbor 1:1 propensity score-matching was used to create comparable groups. Overall survival (OS) was compared between subgroups using Kaplan-Meier analyses. Immortal bias analysis was performed among those who survived longer than 90 days. RESULTS: The study identified 29,728 chemotherapy-treated patients, who were divided into the following four subgroups: no surgery (NS, n = 25,690), metastasectomy alone (n = 1170), gastrectomy alone (n = 2248), and CRS (n = 620) with median OS periods of 8.6, 10.9, 14.8, and 16.3 months, respectively (p < 0.001). Compared with the patients who underwent NS, the patients who had CRS were younger (58.9 ± 13.4 vs 62.0 ± 13.1 years), had a lower proportion of disease involving multiple sites (4.6% vs 19.1%), and were more likely to be clinically occult (cM0 stage: 59.2% vs 8.3%) (p < 0.001 for all). The median OS for the propensity-matched patients who underwent CRS (n = 615) was longer than for those with NS (16.4 vs 9.3 months; p < 0.001), including in those with clinical M1 stage (n = 210). In the Cox regression model using the matched data, the hazard ratio for CRS versus NS was 0.56 (95% confidence interval [CI], 0.49-0.63). In the immortal-matched cohort, the corresponding median OS was 17.0 versus 9.5 months (p < 0.001). CONCLUSIONS: In addition to SC, CRS may be associated with an OS benefit for a selected group of MGA patients meriting further prospective investigation.

Novel Application of Iterative Hyperthermic Intraperitoneal Chemotherapy for Unresectable Peritoneal Metastases from High-Grade Appendiceal Ex-Goblet Adenocarcinoma.

BACKGROUND: Peritoneal metastases (PMs) from appendiceal ex-goblet adenocarcinoma (AEGA) are associated with a poor prognosis. While cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has been shown to prolong survival, the majority of patients are ineligible for complete cytoreduction. We describe a novel approach to the management of such patients with iterative HIPEC (IHIPEC). METHODS: Patients with signet ring/poorly differentiated AEGA with high Peritoneal Cancer Index (PCI) and extensive bowel involvement underwent IHIPEC with mitomycin C at 6-week intervals for a total of three cycles. Survival outcomes for these patients were compared with patients with high-grade appendiceal tumors matched for tumor burden who were treated with other conventional approaches, i.e. systemic chemotherapy only (SCO) or complete CRS + HIPEC. RESULTS: Between 2016 and 2019, seven AEGA patients with high PCI (median 32.5 [range 21-36]) underwent 18 IHIPEC cycles (median cycles per patient 3 [2-3]) in combination with systemic chemotherapy (median 2 lines [1-3], 12 cycles [10-28]). IHIPEC was delivered laparoscopically in 14/18 cases. Postoperatively, the median length of stay was 1 day (1-8 days), no procedure-related complications were reported, and five (28%) 90-day readmissions for bowel obstruction were documented. Median overall survival after IHIPEC was better compared with a matched group of patients (n = 16) receiving SCO (24.6 vs. 7.9 months; p = 0.005), and similar to those (n = 7) who underwent CRS + HIPEC (24.6 vs. 16.5 months; p = 0.62). CONCLUSIONS: IHIPEC in combination with systemic chemotherapy is tolerable, safe, and may be associated with encouraging survival outcomes compared with SCO in selected patients with high-grade, high-burden AEGA PM.

MAHOGANY: margetuximab combination in HER2+ unresectable/metastatic gastric/gastroesophageal junction adenocarcinoma.

Standard-of-care, first-line therapy for patients with advanced HER2+ gastric/gastroesophageal junction adenocarcinoma is chemotherapy plus trastuzumab, a monoclonal antibody (mAb) targeting HER2. Margetuximab is an Fc-optimized mAb that binds HER2. Retifanlimab, a humanized IgG4 mAb, binds to PD-1 and blocks its interaction with PD-L1/2. Tebotelimab, an IgG4κ bispecific DART® molecule, binds PD-1 and lymphocyte activation gene 3 concomitantly, disrupting these nonredundant inhibitory pathways to further restore exhausted T-cell function. Here, we describe the design and rationale of the randomized, open-label, Phase II/III MAHOGANY trial evaluating margetuximab plus retifanlimab with/without chemotherapy and margetuximab plus tebotelimab with chemotherapy in first-line unresectable metastatic/locally advanced gastroesophageal junction adenocarcinoma. Primary end points include objective response rate, overall survival and safety/tolerability. Clinical trial registration: NCT04082364 (ClinicalTrials.gov).

Pemigatinib for previously treated, locally advanced or metastatic cholangiocarcinoma: a multicentre, open-label, phase 2 study.

BACKGROUND: Fibroblast growth factor receptor (FGFR) 2 gene alterations are involved in the pathogenesis of cholangiocarcinoma. Pemigatinib is a selective, potent, oral inhibitor of FGFR1, 2, and 3. This study evaluated the safety and antitumour activity of pemigatinib in patients with previously treated, locally advanced or metastatic cholangiocarcinoma with and without FGFR2 fusions or rearrangements. METHODS: In this multicentre, open-label, single-arm, multicohort, phase 2 study (FIGHT-202), patients aged 18 years or older with disease progression following at least one previous treatment and an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 recruited from 146 academic or community-based sites in the USA, Europe, the Middle East, and Asia were assigned to one of three cohorts: patients with FGFR2 fusions or rearrangements, patients with other FGF/FGFR alterations, or patients with no FGF/FGFR alterations. All enrolled patients received a starting dose of 13·5 mg oral pemigatinib once daily (21-day cycle; 2 weeks on, 1 week off) until disease progression, unacceptable toxicity, withdrawal of consent, or physician decision. The primary endpoint was the proportion of patients who achieved an objective response among those with FGFR2 fusions or rearrangements, assessed centrally in all patients who received at least one dose of pemigatinib. This study is registered with ClinicalTrials.gov, NCT02924376, and enrolment is completed. FINDINGS: Between Jan 17, 2017, and March 22, 2019, 146 patients were enrolled: 107 with FGFR2 fusions or rearrangements, 20 with other FGF/FGFR alterations, 18 with no FGF/FGFR alterations, and one with an undetermined FGF/FGFR alteration. The median follow-up was 17·8 months (IQR 11·6-21·3). 38 (35·5% [95% CI 26·5-45·4]) patients with FGFR2 fusions or rearrangements achieved an objective response (three complete responses and 35 partial responses). Overall, hyperphosphataemia was the most common all-grade adverse event irrespective of cause (88 [60%] of 146 patients). 93 (64%) patients had a grade 3 or worse adverse event (irrespective of cause); the most frequent were hypophosphataemia (18 [12%]), arthralgia (nine [6%]), stomatitis (eight [5%]), hyponatraemia (eight [5%]), abdominal pain (seven [5%]), and fatigue (seven [5%]). 65 (45%) patients had serious adverse events; the most frequent were abdominal pain (seven [5%]), pyrexia (seven [5%]), cholangitis (five [3%]), and pleural effusion (five [3%]). Overall, 71 (49%) patients died during the study, most frequently because of disease progression (61 [42%]); no deaths were deemed to be treatment related. INTERPRETATION: These data support the therapeutic potential of pemigatinib in previously treated patients with cholangiocarcinoma who have FGFR2 fusions or rearrangements. FUNDING: Incyte Corporation.

Ivosidenib in IDH1-mutant, chemotherapy-refractory cholangiocarcinoma (ClarIDHy): a multicentre, randomised, double-blind, placebo-controlled, phase 3 study.

BACKGROUND: Isocitrate dehydrogenase 1 (IDH1) mutations occur in approximately 13% of patients with intrahepatic cholangiocarcinoma, a relatively uncommon cancer with a poor clinical outcome. The aim of this international phase 3 study was to assess the efficacy and safety of ivosidenib (AG-120)-a small-molecule targeted inhibitor of mutated IDH1-in patients with previously treated IDH1-mutant cholangiocarcinoma. METHODS: This multicentre, randomised, double-blind, placebo-controlled, phase 3 study included patients from 49 hospitals in six countries aged at least 18 years with histologically confirmed, advanced, IDH1-mutant cholangiocarcinoma who had progressed on previous therapy, and had up to two previous treatment regimens for advanced disease, an Eastern Cooperative Oncology Group performance status score of 0 or 1, and a measurable lesion as defined by Response Evaluation Criteria in Solid Tumors version 1.1. Patients were randomly assigned (2:1) with a block size of 6 and stratified by number of previous systemic treatment regimens for advanced disease to oral ivosidenib 500 mg or matched placebo once daily in continuous 28-day cycles, by means of an interactive web-based response system. Placebo to ivosidenib crossover was permitted on radiological progression per investigator assessment. The primary endpoint was progression-free survival by independent central review. The intention-to-treat population was used for the primary efficacy analyses. Safety was assessed in all patients who had received at least one dose of ivosidenib or placebo. Enrolment is complete; this study is registered with ClinicalTrials.gov, NCT02989857. FINDINGS: Between Feb 20, 2017, and Jan 31, 2019, 230 patients were assessed for eligibility, and as of the Jan 31, 2019 data cutoff date, 185 patients were randomly assigned to ivosidenib (n=124) or placebo (n=61). Median follow-up for progression-free survival was 6·9 months (IQR 2·8-10·9). Progression-free survival was significantly improved with ivosidenib compared with placebo (median 2·7 months [95% CI 1·6-4·2] vs 1·4 months [1·4-1·6]; hazard ratio 0·37; 95% CI 0·25-0·54; one-sided p<0·0001). The most common grade 3 or worse adverse event in both treatment groups was ascites (four [7%] of 59 patients receiving placebo and nine [7%] of 121 patients receiving ivosidenib). Serious adverse events were reported in 36 (30%) of 121 patients receiving ivosidenib and 13 (22%) of 59 patients receiving placebo. There were no treatment-related deaths. INTERPRETATION: Progression-free survival was significantly improved with ivosidenib compared with placebo, and ivosidenib was well tolerated. This study shows the clinical benefit of targeting IDH1 mutations in advanced, IDH1-mutant cholangiocarcinoma. FUNDING: Agios Pharmaceuticals.

Margetuximab plus pembrolizumab in patients with previously treated, HER2-positive gastro-oesophageal adenocarcinoma (CP-MGAH22-05): a single-arm, phase 1b-2 trial.

BACKGROUND: Margetuximab, a novel, investigational, Fc-engineered, anti-HER2 monoclonal antibody, is designed to more effectively potentiate innate immunity than trastuzumab. We aimed to evaluate the safety, tolerability, and antitumour activity of margetuximab plus pembrolizumab (an anti-PD-1 monoclonal antibody) in previously treated patients with HER2-positive gastro-oesophageal adenocarcinoma. METHODS: CP-MGAH22-05 was a single-arm, open-label, phase 1b-2 dose-escalation and cohort expansion study done at 11 academic centres in the USA and Canada and 15 centres in southeast Asia (Korea, Taiwan, and Singapore) that enrolled men and women aged 18 years or older with histologically proven, unresectable, locally advanced or metastatic, HER2-positive, PD-L1-unselected gastro-oesophageal adenocarcinoma, with an Eastern Cooperative Oncology Group performance status of 0 or 1, who had progressed after at least one previous line of therapy with trastuzumab plus chemotherapy in the locally advanced unresectable or metastatic setting. In the dose-escalation phase, nine patients were treated: three received margetuximab 10 mg/kg intravenously plus pembrolizumab 200 mg intravenously every 3 weeks and six received the recommended phase 2 dose of margetuximab 15 mg/kg plus pembrolizumab 200 mg intravenously every 3 weeks. An additional 86 patients were enrolled in the phase 2 cohort expansion and received the recommended phase 2 dose. The primary endpoints were safety and tolerability, assessed in the safety population (patients who received at least one dose of either margetuximab or pembrolizumab) and the objective response rate as assessed by the investigator according to both Response Evaluation Criteria in Solid Tumors (RECIST), version 1.1, in the response-evaluable population (patients with measurable disease at baseline and who received the recommended phase 2 dose of margetuximab and pembrolizumab). This trial is registered with ClinicalTrials.gov, NCT02689284. Recruitment for the trial has completed and follow-up is ongoing. FINDINGS: Between Feb 11, 2016, and Oct 2, 2018, 95 patients were enrolled. Median follow-up was 19·9 months (IQR 10·7-23·1). The combination therapy showed acceptable safety and tolerability; there were no dose-limiting toxicities in the dose-escalation phase. The most common grade 3-4 treatment-related adverse events were anaemia (four [4%]) and infusion-related reactions (three [3%]). Serious treatment-related adverse events were reported in nine (9%) patients. No treatment-related deaths were reported. Objective responses were observed in 17 (18·48%; 95% CI 11·15-27·93) of 92 evaluable patients. INTERPRETATION: These findings serve as proof of concept of synergistic antitumour activity with the combination of an Fc-optimised anti-HER2 agent (margetuximab) along with anti-PD-1 checkpoint blockade (pembrolizumab). FUNDING: MacroGenics.

A UGT1A1 genotype-guided dosing study of modified FOLFIRINOX in previously untreated patients with advanced gastrointestinal malignancies.

BACKGROUND: FOLFIRINOX (5-fluorouracil [5-FU], leucovorin, irinotecan, oxaliplatin) is an effective but toxic therapy for pancreatic cancer. UGT1A1 (UDP glucuronosyltransferase 1A1) eliminates the active metabolite of irinotecan. Polymorphisms reduce UGT1A1 activity, leading to toxicity. The primary objective was to determine the dose-limiting toxicity (DLT) rate in cycle 1 of modified FOLFIRINOX (mFOLFIRINOX) using genotype-guided dosing of irinotecan for the most common UGT1A1 genotypes (*1/*1, *1/*28) in advanced gastrointestinal malignancies, with expansion in pancreatic and biliary tract cancers. METHOD: 5-FU (2400 mg/m2 over 46 hours), leucovorin (400 mg/m2 ), oxaliplatin (85 mg/m2 ), and irinotecan were given every 14 days. Irinotecan doses of 180, 135, and 90 mg/m2 were administered for UGT1A1 genotypes *1/*1, *1/*28, and *28/*28, respectively. Prophylactic pegfilgrastim was omitted in cycle 1 for cohort 1 (tolerability by genotype), but was given in cohort 2 (tolerability by tumor type). Doses were tolerable if the upper limit of a 2-sided 80% confidence interval for DLT rate was ≤33%. RESULTS: In cohort 1, DLTs (most commonly febrile neutropenia, fatigue, diarrhea) occurred in 2/15 (13%), 3/16 (19%), and 4/10 (40%) patients with *1/*1, *1/*28, and *28/*28 genotypes, respectively. In cohort 2, 6/19 (32%) pancreatic and 4/19 (21%) biliary tract cancer patients experienced DLTs (most commonly fatigue, diarrhea, nausea/vomiting). In cohort 2, upper confidence limits of DLT rates exceeded 33%. Response rates were 38% in pancreatic and 21% in biliary tract cancers. CONCLUSION: On the basis of our prespecified criteria, tolerability of UGT1A1 genotype-guided mFOLFIRINOX was not established in pancreatic and biliary tract cancers. However, this regimen was effective.

Initial Report of Second-Line FOLFIRI in Combination with Ramucirumab in Advanced Gastroesophageal Adenocarcinomas: A Multi-Institutional Retrospective Analysis.

BACKGROUND: The randomized phase III RAINBOW trial established paclitaxel (pac) plus ramucirumab (ram) as a global standard for second-line (2L) therapy in advanced gastric and gastroesophageal junction adenocarcinoma, together gastroesophageal adenocarcinoma (GEA). Patients (pts) receiving first-line (1L) FOLFOX often develop neuropathy that renders continued neurotoxic agents in the 2L setting unappealing and other regimens more desirable. As such, FOLFIRI-ram has become an option for patients with 2L GEA. FOLFIRI-ramucirumab (ram) has demonstrated safety and activity in 2L colorectal cancer, but efficacy/safety data in GEA are lacking. SUBJECTS, MATERIALS, AND METHODS: Patients with GEA treated with 2L FOLFIRI-ram between August 2014 and April 2018 were identified. Clinicopathologic data including oxaliplatin neurotoxicity rates/grades (G), 2L treatment response, progression-free survival (PFS), overall survival (OS), safety, and molecular features were abstracted from three U.S. academic institutions. Kaplan-Meier survival analysis was used to generate PFS/OS; the likelihood ratio test was used to determine statistical significance. RESULTS: We identified 29 pts who received 2L FOLFIRI-ram. All pts received 1L platinum + fluoropyrimidine, and 23 of 29 (79%) had post-1L neuropathy; 12 (41%) had G1, and 11 (38%) had G2. Patients were evenly split between esophagus/gastroesophageal junction (12; 41%) and gastric cancer (17; 59%). Among evaluable pts (26/29), the overall response rate was 23% (all partial response) with a disease control rate of 79%. Median PFS was 6.0 months and median OS was 13.4 months among all evaluable pts. Six- and 12-month OS were 90% (n = 18/20) and 41% (n = 7/17). There were no new safety signals. CONCLUSION: We provide the first data suggesting FOLFIRI-ram is a safe, non-neurotoxic regimen comparing favorably with the combination of pac + ram used in the seminal RAINBOW trial. IMPLICATIONS FOR PRACTICE: Results of this study provide initial support for the safety and efficacy of second-line (2L) FOLFIRI-ramucirumab (ram) after progression on first-line platinum/fluoropyrimidine in patients with gastroesophageal adenocarcinoma (GEA). The overall response, progression-free survival, overall survival, and toxicity profile compare favorably with paclitaxel (pac) + ram and highlight the importance of the ongoing phase II RAMIRIS trial examining FOLFIRI-ram versus pac + ram in 2L GEA (NCT03081143). FOLFIRI-ram may warrant consideration for inclusion as an alternate regimen in consensus guidelines for GEA.

Analysis of DNA Damage Response Gene Alterations and Tumor Mutational Burden Across 17,486 Tubular Gastrointestinal Carcinomas: Implications for Therapy.

BACKGROUND: Alterations in the DNA damage response (DDR) pathway confer sensitivity to certain chemotherapies, radiation, and other DNA damage repair targeted therapies. BRCA1/2 are the most well-studied DDR genes, but recurrent alterations are described in other DDR pathway members across cancers. Deleterious DDR alterations may sensitize tumor cells to poly (ADP-ribose) polymerase inhibition, but there are also increasing data suggesting that there may also be synergy with immune checkpoint inhibitors. The relevance of DDR defects in gastrointestinal (GI) cancers is understudied. We sought to characterize DDR-defective GI malignancies and to explore genomic context and tumor mutational burden (TMB) to provide a platform for future rational investigations. MATERIALS AND METHODS: Tumor samples from 17,486 unique patients with advanced colorectal, gastroesophageal, or small bowel carcinomas were assayed using hybrid-capture-based comprehensive genomic profiling including sequencing of 10 predefined DDR genes: ARID1A, ATM, ATR, BRCA1, BRCA2, CDK12, CHEK1, CHEK2, PALB2, and RAD51. TMB (mutations per megabase [mut/Mb]) was calculated from up to 1.14 Mb of sequenced DNA. Clinicopathologic features were extracted and descriptive statistics were used to explore genomic relationships among identified subgroups. RESULTS: DDR alterations were found in 17% of cases: gastric adenocarcinoma 475/1,750 (27%), small bowel adenocarcinoma 148/666 (22%), esophageal adenocarcinoma 467/2,501 (19%), and colorectal cancer 1,824/12,569 (15%). ARID1A (9.2%) and ATM (4.7%) were the most commonly altered DDR genes in this series, followed by BRCA2 (2.3%), BRCA1 (1.1%), CHEK2 (1.0%), ATR (0.8%), CDK12 (0.7%), PALB2 (0.6%), CHEK1 (0.1%) and RAD51 (0.1%). More than one DDR gene alteration was found in 24% of cases. High microsatellite instability (MSI-H) and high TMB (TMB-H, ≥20 mut/Mb) were found in 19% and 21% of DDR-altered cases, respectively. Of DDR-altered/TMB-H cases, 87% were also MSI-H. However, even in the microsatellite stable (MSS)/DDR-wild-type (WT) versus MSS/DDR-altered, TMB-high was seen more frequently (0.4% vs. 3.3%, P < .00001.) Median TMB was 5.4 mut/Mb in the MSS/DDR-altered subset versus 3.8 mut/Mb in the MSS/DDR-WT subset (P ≤ .00001), and ATR alterations were enriched in the MSS/TMB-high cases. CONCLUSION: This is the largest study to examine selected DDR defects in tubular GI cancers and confirms that DDR defects are relatively common and that there is an association between the selected DDR defects and a high TMB in more than 20% of cases. Microsatellite stable DDR-defective tumors with elevated TMB warrant further exploration. IMPLICATIONS FOR PRACTICE: Deleterious DNA damage response (DDR) alterations may sensitize tumor cells to poly (ADP-ribose) polymerase inhibition, but also potentially to immune checkpoint inhibitors, owing to accumulation of mutations in DDR-defective tumors. The relevance of DDR defects in gastrointestinal (GI) cancers is understudied. This article characterizes DDR-defective GI malignancies and explores genomic context and tumor mutational burden to provide a platform for future rational investigations.

FGFR2-Altered Gastroesophageal Adenocarcinomas Are an Uncommon Clinicopathologic Entity with a Distinct Genomic Landscape.

BACKGROUND: With the exception of trastuzumab, therapies directed at receptor tyrosine kinases (RTKs) in gastroesophageal adenocarcinomas (GEA) have had limited success. Recurrent fibroblast growth factor receptor 2 (FGFR2) alterations exist in GEA; however, little is known about the genomic landscape of FGFR2-altered GEA. We examined FGFR2 alteration frequency and frequency of co-occurring alterations in GEA. SUBJECTS, MATERIALS, AND METHODS: A total of 6,667 tissue specimens from patients with advanced GEA were assayed using hybrid capture-based genomic profiling. Tumor mutational burden (TMB) was determined on up to 1.1 Mb of sequenced DNA, and microsatellite instability was determined on 95 or 114 loci. Descriptive statistics were used to compare subgroups. RESULTS: We identified a total of 269 (4.0%) FGFR2-altered cases consisting of FGFR2-amplified (amp; 193, 72% of FGFR2-altered), FGFR2-mutated (36, 13%), FGFR2-rearranged (re; 23, 8.6%), and cases with multiple FGFR2 alterations (17, 6.3%). Co-occurring alterations in other GEA RTK targets including ERBB2 (10%), EGFR (8%), and MET (3%) were observed across all classes of FGFR2-altered GEA. Co-occurring alterations in MYC (17%), KRAS (10%), and PIK3CA (5.6%) were also observed frequently. Cases with FGFR2amp and FGFR2re were exclusively microsatellite stable. The median TMB for FGFR2-altered GEA was 3.6 mut/mb, not significantly different from a median of 4.3 mut/mb seen in FGFR2 wild-type samples. CONCLUSION: FGFR2-altered GEA is a heterogenous subgroup with approximately 20% of FGFR2-altered samples harboring concurrent RTK alterations. Putative co-occurring modifiers of FGFR2-directed therapy including oncogenic MYC, KRAS, and PIK3CA alterations were also frequent, suggesting that pretreatment molecular analyses may be needed to facilitate rational combination therapies and optimize patient selection for clinical trials. IMPLICATIONS FOR PRACTICE: Actionable receptor tyrosine kinase alterations assayed within a genomic context with therapeutic implications remain limited to HER2 amplification in gastroesophageal adenocarcinomas (GEA). Composite biomarkers and heterogeneity assessment are critical in optimizing patients selected for targeted therapies in GEA. Comprehensive genomic profiling in FGFR2-altered GEA parallels the heterogeneity findings in HER2-amplified GEA and adds support to the utility of genomic profiling in advanced gastroesophageal adenocarcinomas.

Pembrolizumab alone or in combination with chemotherapy as first-line therapy for patients with advanced gastric or gastroesophageal junction adenocarcinoma: results from the phase II nonrandomized KEYNOTE-059 study.

BACKGROUND: The multicohort, phase II, nonrandomized KEYNOTE-059 study evaluated pembrolizumab ± chemotherapy in advanced gastric/gastroesophageal junction cancer. Results from cohorts 2 and 3, evaluating first-line therapy, are presented. METHODS: Patients ≥ 18 years old had previously untreated recurrent or metastatic gastric/gastroesophageal junction adenocarcinoma. Cohort 3 (monotherapy) had programmed death receptor 1 combined positive score ≥ 1. Cohort 2 (combination therapy) received pembrolizumab 200 mg on day 1, cisplatin 80 mg/m2 on day 1 (up to 6 cycles), and 5-fluorouracil 800 mg/m2 on days 1-5 of each 3-week cycle (or capecitabine 1000 mg/m2 twice daily in Japan). Primary end points were safety (combination therapy) and objective response rate per Response Evaluation Criteria in Solid Tumors version 1.1 by central review, and safety (monotherapy). RESULTS: In the combination therapy and monotherapy cohorts, 25 and 31 patients were enrolled; median follow-up was 13.8 months (range 1.8-24.1) and 17.5 months (range 1.7-20.7), respectively. In the combination therapy cohort, grade 3/4 treatment-related adverse events occurred in 19 patients (76.0%); none were fatal. In the monotherapy cohort, grade 3-5 treatment-related adverse events occurred in seven patients (22.6%); one death was attributed to a treatment-related adverse event (pneumonitis). The objective response rate was 60.0% [95% confidence interval (CI), 38.7-78.9] (combination therapy) and 25.8% (95% CI 11.9-44.6) (monotherapy). CONCLUSIONS: Pembrolizumab demonstrated antitumor activity and was well tolerated as monotherapy and in combination with chemotherapy in patients with previously untreated advanced gastric/gastroesophageal junction adenocarcinoma. CLINICAL TRIAL: ClinicalTrials.gov NCT02335411.

Bemarituzumab with modified FOLFOX6 for advanced FGFR2-positive gastroesophageal cancer: FIGHT Phase III study design.

Bemarituzumab is an afucosylated monoclonal antibody against FGFR2b (a FGF receptor) with demonstrated monotherapy clinical activity in patients with late-line gastric cancer whose tumors overexpress FGFR2b (NCT02318329). We describe the rationale and design of the FIGHT trial (NCT03343301), a global, randomized, double-blind, placebo-controlled Phase III study evaluating the role of bemarituzumab in patients with previously untreated, FGFR2b-overexpressing advanced gastroesophageal cancer. Patients are randomized in a blinded fashion to the combination of mFOLFOX6 and bemarituzumab or mFOLFOX6 and placebo. Eligible patients are selected based on the presence of either FGFR2b protein overexpression determined by immunohistochemistry or FGFR2 gene amplification determined by circulating tumor DNA. The primary end point is overall survival, and secondary end points include progression-free survival, objective response rate and safety.

Primary systemic therapy in resectable pancreatic ductal adenocarcinoma using mFOLFIRINOX: A pilot study.

BACKGROUND AND OBJECTIVES: Surgery followed by gemcitabine and/or a fluoropyrimidine is standard therapy for resectable PDAC. mFOLFIRINOX (oxaliplatin 85 mg/m2 , irinotecan 180 mg/m2 , leucovorin 400 mg/m2 Day 1, 5-FU 2400 mg/m2 × 48 h IV, peg-filgrastim 6 mg SQ day 3, every 14 days) has substantial activity in metastatic PDAC. We wished to determine the tolerability/efficacy of peri-operative mFOLFIRINOX in resectable PDAC. METHODS: Patients with resectable PDAC (ECOG PS 0/1) received four cycles of mFOLFIRINOX pre- and post-surgery. The primary endpoint was completion of preoperative chemotherapy plus resection. Secondary endpoints included completion of all therapy, R0 resection, treatment related toxicity, PFS, and OS. RESULTS: Twenty-one patients enrolled: median age 62 (47-78); 20/21 (95%) completed four cycles of preoperative mFOLFIRINOX; response by RECIST was 1 CR, 3 PR, 16 SD; 17/21 (81%) completed resection, 16/21 (76%) R0; 14/21 (66%) completed four cycles of postoperative mFOLFIRINOX. Grade 3 and 4 toxicity occurred in 23% and 14% patients pre-operatively, 26% and 6.0% post-operatively. Nine patients are alive with median follow-up of 27.7 (3.1-47.1) months. CONCLUSIONS: PST using mFOLFIRINOX in resectable PDAC is feasible and tolerable. R0 resection rate is high and survival promising, requiring longer follow-up and larger studies for definitive assessment.

Pembrolizumab for treatment of advanced gastric and gastroesophageal junction adenocarcinoma.

Pembrolizumab is a monoclonal antibody directed against PD-1 that is US FDA approved for treatment of advanced PD-L1 positive gastric and gastroesophageal junction adenocarcinoma in patients who have progressed on at least two prior lines of chemotherapy. This article summarizes the clinical evidence regarding safety, tolerability and efficacy of pembrolizumab in this setting. In addition, this article describes the investigational use of pembrolizumab as first- and second-line therapy and in combination with other treatments. Finally, this review compares other checkpoint inhibitors to pembrolizumab for the treatment of this disease, and explores predictive biomarkers of response to PD-1 blockade.