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).

The Clinical Landscape of Cell-Free DNA Alterations in 1,671 Patients with Advanced Biliary Tract Cancer

BACKGROUND

Targeted therapies have transformed clinical management of advanced biliary tract cancer (BTC). Cell-free DNA (cfDNA) analysis is an attractive approach for cancer genomic profiling that overcomes many limitations of traditional tissue-based analysis. We examined cfDNA as a tool to inform clinical management of patients with advanced BTC and generate novel insights into BTC tumor biology.

PATIENTS AND METHODS

We analyzed next-generation sequencing data of 2,068 cfDNA samples from 1,671 patients with advanced BTC generated with Guardant360. We performed clinical annotation on a multi-institutional subset (n=225) to assess intra-patient cfDNA-tumor concordance and the association of cfDNA variant allele fraction (VAF) with clinical outcomes.

RESULTS

Genetic alterations were detected in cfDNA in 84% of patients, with targetable alterations detected in 44% of patients. FGFR2 fusions, IDH1 mutations, and BRAF V600E were clonal in majority of cases, affirming these targetable alterations as early driver events in BTC. Concordance between cfDNA and tissue for mutation detection was high for IDH1 mutations (87%) and BRAF V600E (100%), and low for FGFR2 fusions (18%). cfDNA analysis uncovered novel putative mechanisms of resistance to targeted therapies, including mutation of the cysteine residue (FGFR2 C492F) to which covalent FGFR inhibitors bind. High pre-treatment cfDNA VAF associated with poor prognosis and shorter response to chemotherapy and targeted therapy. Finally, we report the frequency of promising targets in advanced BTC currently under investigation in other advanced solid tumors, including KRAS G12C (1.0%), KRAS G12D (5.1%), PIK3CA mutations (6.8%), and ERBB2 amplifications (4.9%).

CONCLUSIONS

These findings from the largest and most comprehensive study to date of cfDNA from patients with advanced BTC highlight the utility of cfDNA analysis in current management of this disease. Characterization of oncogenic drivers and mechanisms of therapeutic resistance in this study will inform drug development efforts to reduce mortality for patients with BTC.

Margetuximab with retifanlimab as first-line therapy in HER2+/PD-L1+ unresectable or metastatic gastroesophageal adenocarcinoma: MAHOGANY cohort A

Background

Human epidermal growth factor receptor 2 (HER2)-positive metastatic gastric and gastroesophageal adenocarcinoma (GEA) is globally treated with chemotherapy plus trastuzumab. Novel therapeutic strategies strive to not only optimize efficacy, but also limit toxicities. In MAHOGANY cohort A, margetuximab, an Fc-engineered, anti-HER2 monoclonal antibody (mAb) was combined with retifanlimab, an anti-programmed cell death protein 1 mAb, in the first-line HER2-positive/programmed death-ligand 1 (PD-L1)-positive GEA.

Patients and methods

MAHOGANY cohort A part 1 is a single-arm trial to evaluate margetuximab plus retifanlimab in patients with HER2 immunohistochemistry 3+, PD-L1-positive (combined positive score ≥1%), and non-microsatellite instability-high tumors. Primary objectives for cohort A were safety/tolerability and the confirmed objective response rate (ORR).

Results

As of 3 August 2021, 43 patients were enrolled and received margetuximab/retifanlimab. Nine grade 3 treatment-related adverse events (TRAEs) were reported in eight (18.6%) patients and eight serious TRAEs in seven (16.3%) patients. There were no grade 4/5 TRAEs. Three patients discontinued margetuximab/retifanlimab because of immune-related adverse events. The ORR by independent assessment was 53% [21/40 (95% confidence interval (CI) 36.1-68.5)], with a median duration of response of 10.3 months (95% CI 4.6-not evaluable); disease control rate was 73% [29/40 (95% CI 56.1-85.4)]. The study sponsor discontinued the study in advance of the planned enrollment when it became apparent that the study design would no longer meet the requirements for drug approval because of recent advances in the treatment of GEA.

Conclusions

The chemotherapy-free regimen of combined margetuximab/retifanlimab as first-line treatment in double biomarker-selected patients demonstrated a favorable toxicity profile compared with historical outcomes using chemotherapy plus trastuzumab. The ORR observed in this study compares favorably versus ORR observed with other chemotherapy-free approaches.

•

The margetuximab/retifanlimab regimen has a favorable toxicity profile versus historical chemotherapy-based regimens in GEA.

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The margetuximab/retifanlimab regimen as first-line therapy for GEA met the prespecified boundary for antitumor activity.

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The 53% ORR [21/40 (95% CI 36.1-68.5)] in the combined regimen compared favorably with other chemotherapy-free approaches.

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Median duration of response was 10.3 months (95% CI 4.57-not evaluable) and disease control rate was 73% [29/40 (95% CI 56.1-85.4)].

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The study was discontinued for business reasons as chemotherapy-based regimens remain the dominant therapy for GEA.

Epidermal Growth Factor Receptor Inhibition in Epidermal Growth Factor Receptor-Amplified Gastroesophageal Cancer: Retrospective Global Experience

PURPOSE

Subset analyses from phase III evaluation of epidermal growth factor receptor inhibition (EGFRi) suggest improved outcomes in patients with EGFR-amplified gastroesophageal adenocarcinoma (GEA), but large-scale analyses are lacking. This multi-institutional analysis sought to determine the role of EGFRi in the largest cohort of patients with EGFR-amplified GEA to date.

PATIENTS AND METHODS

A total of 60 patients from 15 tertiary cancer centers in six countries met the inclusion criteria. These criteria required histologically confirmed GEA in the metastatic or unresectable setting with EGFR amplification identified by using a Clinical Laboratory Improvement Amendments-approved assay, and who received on- or off-protocol EGFRi. Testing could be by tissue next-generation sequencing, plasma circulating tumor DNA next-generation sequencing, and/or fluorescence in situ hybridization performed by a Clinical Laboratory Improvement Amendments approved laboratory. Treatment patterns and outcomes analysis was also performed using a deidentified clinicogenomic database (CGDB).

RESULTS

Sixty patients with EGFR-amplified GEA received EGFRi, including 31 of 60 patients (52%) with concurrent chemotherapy. Across treatment lines, patients achieved a 43% objective response rate with a median progression-free survival of 4.6 months (95% CI, 3.5 to 6.4). Patients receiving EGFRi in first-, second-, and third-line therapy achieved a median overall survival of 20.6 months (95% CI, 13.5 to not reached [NR]), 9 months (95% CI, 7.9 to NR), and 8.4 months (7.6 to NR), respectively. This survival far exceeded the 11.2-month (95% CI, 8.7 to 14.2) median overall survival from first-line initiation of non-EGFRi therapy in patients with EGFR-amplified GEA in the CGDB. Despite this benefit, analysis of the CGDB (January 2011-December 2020) suggests that only 5% of patients with EGFR-amplified GEA received EGFRi.

CONCLUSION

Patients with EGFR-amplified GEA derive significant benefit from EGFRi. Further prospective investigation of EGFRi in a well-selected patient population is ongoing in an upcoming trial of amivantamab in EGFR and/or MET amplified GEA.

Utility of Perioperative Measurement of Cell-Free DNA and Circulating Tumor DNA in Informing the Prognosis of GI Cancers: A Systematic Review

PURPOSE

Current surveillance imaging and tumor markers lack sensitivity for the early detection of recurrence in GI cancers. This study critically evaluates the current literature on the role of sequential measurement of circulating tumor DNA (ctDNA) before and after curative resection in informing recurrence.

METHODS

A systematic search using a predefined, registered protocol was conducted for studies published between January 2010 and May 2020. Included studies described patients with GI cancers treated with curative-intent surgical resection and measurement of ctDNA both before and after surgery. Patients were divided into three groups on the basis of the presence or absence of ctDNA at these time points. The primary outcome was recurrence-free survival (RFS).

RESULTS

The search yielded 3,873 articles; five met the inclusion criteria and collectively evaluated 57 patients. Pooled median RFS was 62 months (interquartile range 19 to not reached). Although median RFS was not reached in group 1 (- to -) or group 2 (+ to -), median RFS in group 3 (+ to +) was 15 months (interquartile range 9.6-60.4 months). Cox hazard ratio was 4.46 (95% CI, 1.17 to 16.99; P = .028) between group 1 and group 2, and 10.47 (95% CI, 2.91 to 37.74; P < .001) between group 2 and group 3.

CONCLUSION

Detectable ctDNA, either preoperatively or postoperatively, and its persistence after curative surgery are associated with a greater risk of recurrence and decreased RFS in GI cancers. Thus, perioperative measurement of ctDNA may be a useful postoperative risk stratification tool and guide additional therapies.

Safety and efficacy of HER2 blockade by trastuzumab-based chemotherapy-containing combination strategies in HER2+ gastroesophageal adenocarcinoma

Since completion of the Trastuzumab for Gastric Cancer study, trastuzumab with doublet chemotherapy (a fluoropyrimidine and a platinum) has been the gold-standard first-line therapy for patients with locally advanced unresectable or metastatic human epidermal growth factor receptor 2-positive (HER2+) gastroesophageal adenocarcinoma (GEA). The safety and efficacy of 23 studies of first-line trastuzumab plus doublet chemotherapy, without checkpoint inhibitors (n = 19) or with checkpoint inhibitors (n = 4), conducted in patients with locally advanced unresectable or metastatic HER2+ GEA, including phase II/III, prospective, and retrospective observational studies, were summarized. In studies without checkpoint inhibitors, the median duration of trastuzumab treatment ranged from 19.5 to 39.0 weeks and from 15.3 to 30.0 weeks for chemotherapy. In studies with checkpoint inhibitors, the median duration of pembrolizumab/trastuzumab/chemotherapy was 30 weeks, and 18 weeks for chemotherapy. In studies without checkpoint inhibitors, treatment-emergent adverse events (TEAEs) of grade ≥3 ranged from 32% to 84%. Serious adverse events (SAEs) ranged from 15% to 39%. Adverse events resulting in discontinuation ranged from 0% to 30%. Treatment-related deaths occurred in 0%-9% of patients. In studies with checkpoint inhibitors, TEAEs of grade ≥3 were 57%. SAEs ranged from 31% to 38%. Adverse events resulting in discontinuation ranged from 5% to 24%. Treatment-related deaths occurred in 0%-3% of patients. In studies without checkpoint inhibitors, objective response rate (ORR) ranged from 39% to 82%, median progression-free survival (PFS) from 5.7 to 11.6 months, and median overall survival (OS) from 11.2 to 27.6 months. In studies with checkpoint inhibitors, ORR ranged from 39% to 86%, median PFS from 8.0 to 13.0 months, and median OS from 19.3 to 27.3 months. This review provides a historical benchmark on safety and efficacy of available first-line chemotherapy-based standard of care for patients with locally advanced unresectable or metastatic HER2+ GEA.

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.

Exploring New Approaches for Locally Advanced Gastroesophageal Adenocarcinomas: TNT, Irinotecan, and ctDNA

The authors of a recent pilot study incorporated novel concepts including total neoadjuvant therapy with induction triplet FOLFIRINOX then chemoradiotherapy before surgery, along with ctDNA minimal residual disease analyses demonstrating both feasibility of this approach as well as confirming prognostic value of ctDNA analysis before and after surgery.See related article by Wo et al., p. 6343.

Immune-Checkpoint Inhibition in the Treatment of Gastro-Esophageal Cancer: A Closer Look at the Emerging Evidence

To date, several trials have evaluated the safety and efficacy of immune-checkpoint inhibitors (ICI) for the treatment of gastroesophageal cancers (GEC). In the US, ICIs have established indications for second-line treatment of microsatellite unstable tumors, while their use in third-line settings was recently withdrawn. Notably, the use of ICIs for first-line therapy of GEC is rapidly evolving, which currently includes high PD-L1 expressing tumors, irrespective of HER2 status, and in the adjuvant setting after neoadjuvant chemoradiotherapy in select patients. In this article, we review the results of studies that have evaluated the utility of ICI in the third-line, second-line, first-line, and peri-operative treatment settings of GECs. Considerations should be made before making any cross-trial comparisons since these trials vary in chemotherapy backbone, anatomical and histological eligibility, biomarker assessment, PD-L1 diagnostic antibodies, and definition of PD-L1 positivity. Regardless, the totality of the data suggest that first-line ICI use may most benefit GEC patients with high PD-L1 combined positivity score (CPS) ≥5 or ≥10, irrespective of histology or anatomy. Moreover, although PD-L1 by CPS has a good negative predictive value for significant benefit from ICIs, it has a low positive predictive value. Therefore, there is a pressing need to identify better biomarkers to predict benefit from ICIs among these patients.

Final Overall Survival Efficacy Results of Ivosidenib for Patients With Advanced Cholangiocarcinoma With IDH1 Mutation: The Phase 3 Randomized Clinical ClarIDHy Trial

Question

Does ivosidenib treatment improve overall survival outcomes vs placebo among patients with chemotherapy-refractory cholangiocarcinoma with IDH1 mutation?

Findings

In this phase 3 randomized clinical trial including 187 previously treated patients with advanced cholangiocarcinoma with IDH1 mutation, ivosidenib treatment resulted in numerically improved overall survival benefits vs placebo, despite a high rate of crossover. Ivosidenib preserved certain quality of life subscales and was well tolerated.

Meaning

The combined efficacy data and tolerable safety profile, as well as corroborating quality of life data, support the clinical benefit of ivosidenib relative to placebo in cholangiocarcinoma with IDH1 mutation, which has an unmet need for new treatments.

Importance

Isocitrate dehydrogenase 1 (IDH1) variations occur in up to approximately 20% of patients with intrahepatic cholangiocarcinoma. In the ClarIDHy trial, progression-free survival as determined by central review was significantly improved with ivosidenib vs placebo.

Objective

To report the final overall survival (OS) results from the ClarIDHy trial, which aimed to demonstrate the efficacy of ivosidenib (AG-120)—a first-in-class, oral, small-molecule inhibitor of mutant IDH1—vs placebo for patients with unresectable or metastatic cholangiocarcinoma with IDH1 mutation.

Design, Setting, and Participants

This multicenter, randomized, double-blind, placebo-controlled, clinical phase 3 trial was conducted from February 20, 2017, to May 31, 2020, at 49 hospitals across 6 countries among patients aged 18 years or older with cholangiocarcinoma with IDH1 mutation whose disease progressed with prior therapy.

Interventions

Patients were randomized 2:1 to receive ivosidenib, 500 mg, once daily or matched placebo. Crossover from placebo to ivosidenib was permitted if patients had disease progression as determined by radiographic findings.

Main Outcomes and Measures

The primary end point was progression-free survival as determined by blinded independent radiology center (reported previously). Overall survival was a key secondary end point. The primary analysis of OS followed the intent-to-treat principle. Other secondary end points included objective response rate, safety and tolerability, and quality of life.

Results

Overall, 187 patients (median age, 62 years [range, 33-83 years]) were randomly assigned to receive ivosidenib (n = 126; 82 women [65%]; median age, 61 years [range, 33-80 years]) or placebo (n = 61; 37 women [61%]; median age, 63 years [range, 40-83 years]); 43 patients crossed over from placebo to ivosidenib. The primary end point of progression-free survival was reported elsewhere. Median OS was 10.3 months (95% CI, 7.8-12.4 months) with ivosidenib vs 7.5 months (95% CI, 4.8-11.1 months) with placebo (hazard ratio, 0.79 [95% CI, 0.56-1.12]; 1-sided P = .09). When adjusted for crossover, median OS with placebo was 5.1 months (95% CI, 3.8-7.6 months; hazard ratio, 0.49 [95% CI, 0.34-0.70]; 1-sided P < .001). The most common grade 3 or higher treatment-emergent adverse event (≥5%) reported in both groups was ascites (11 patients [9%] receiving ivosidenib and 4 patients [7%] receiving placebo). Serious treatment-emergent adverse events considered ivosidenib related were reported in 3 patients (2%). There were no treatment-related deaths. Patients receiving ivosidenib reported no apparent decline in quality of life compared with placebo.

Conclusions and Relevance

This randomized clinical trial found that ivosidenib was well tolerated and resulted in a favorable OS benefit vs placebo, despite a high rate of crossover. These data, coupled with supportive quality of life data and a tolerable safety profile, demonstrate the clinical benefit of ivosidenib for patients with advanced cholangiocarcinoma with IDH1 mutation.

Trial Registration

ClinicalTrials.gov Identifier: NCT02989857

Trifluridine/tipiracil versus placebo for third or later lines of treatment in metastatic gastric cancer: an exploratory subgroup analysis from the TAGS study

BACKGROUND

Metastatic gastric cancer and cancer of the esophagogastric junction (GC/EGJ) is an aggressive disease with poor prognosis. In the TAGS study, trifluridine/tipiracil (FTD/TPI) improved overall survival (OS) compared with placebo in heavily pre-treated patients. This unplanned, exploratory subgroup analysis of the TAGS study aimed to clarify outcomes when FTD/TPI was used as third-line (3L) treatment and fourth- or later-line (4L+) treatment.

PATIENTS AND METHODS

Patients were divided into a 3L group (126 and 64 in FTD/TPI and placebo arms, respectively) and 4L+ group (211 and 106 in FTD/TPI and placebo arms, respectively). Endpoints included OS, progression-free survival (PFS), time to Eastern Cooperative Oncology Group performance status (ECOG PS) deterioration to ≥2, and safety.

RESULTS

Baseline characteristics were generally well balanced between FTD/TPI and placebo for 3L and 4L+ treatment. Median OS (mOS) for FTD/TPI versus placebo was: 6.8 versus 3.2 months {hazard ratio (HR) [95% confidence interval (CI)] = 0.68 (0.47-0.97), P = 0.0318} in the 3L group; and 5.2 versus 3.7 months [0.73 (0.55-0.95), P = 0.0192] in the 4L+ group. Median PFS for FTD/TPI versus placebo was 3.1 versus 1.9 months [0.54 (0.38-0.77), P = 0.0004] in the 3L group; and 1.9 versus 1.8 months [0.57 (0.44-0.74), P < 0.0001] in the 4L+ group. Time to deterioration of ECOG PS to ≥2 for FTD/TPI versus placebo was 4.8 versus 2.0 months [HR (95% CI) = 0.60 (0.42-0.86), P = 0.0049] in the 3L group; and 4.0 versus 2.5 months [0.75 (0.57-0.98), P = 0.0329] in the 4L+ group. The safety of FTD/TPI was consistent in all subgroups.

CONCLUSIONS

This analysis confirms the efficacy and safety of FTD/TPI in patients with GC/EGJ in third and later lines with a survival benefit that seems slightly superior in 3L treatment. When FTD/TPI is taken in 3L as recommended in the international guidelines, physicians can expect to provide patients with an mOS of 6.8 months.

A PERFECT Biomarker-focused Study of Neoadjuvant IO for Esophagogastric Cancer

To evaluate feasibility and efficacy, checkpoint inhibitor atezolizumab was added to neoadjuvant chemoradiotherapy prior to surgery for esophagogastric adenocarcinoma. The approach was deemed feasible, and while it did not demonstrate better clinical outcome to propensity-matched patients, biomarker investigation demonstrated that high inflammation in the sample at baseline predicted therapeutic benefit.See related article by van den Ende et al., p. 3351.

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.

Spatial and Temporal Heterogeneity of PD-L1 Expression and Tumor Mutational Burden in Gastroesophageal Adenocarcinoma at Baseline Diagnosis and after Chemotherapy

PURPOSE

Intrapatient heterogeneity of programmed death ligand 1 (PD-L1) expression and tumor mutational burden (TMB) in gastroesophageal adenocarcinoma (GEA) could influence their roles as predictive biomarkers for response to immune checkpoint inhibitors (ICI). In this retrospective analysis, we evaluated the spatiotemporal heterogeneity and prognostic relevance of PD-L1 expression and TMB in GEA.

EXPERIMENTAL DESIGN

A cohort of 211 patients with stage II-IV GEA was retrospectively reviewed for a total of 407 tumor samples with PD-L1 expression data and 319 tumor samples with TMB data. PD-L1 status was defined as positive if combined positive score (CPS) ≥1 using the 22C3 pharmDx assay. TMB levels were categorized as low, intermediate, or high (≤5, 5-15, or >15 mutations/Mb), or using a single threshold (<10 or ≥10 mutation/Mb), determined by next-generation sequencing using a targeted gene panel.

RESULTS

Of 407 tumors, 56% were PD-L1 negative and 44% PD-L1 positive. Of 319 tumors, 50% were TMB-low, 45% TMB-intermediate, and 5% TMB-high; 86% had <10 and 14% ≥10 mutations/Mb. TMB level was significantly associated with MSI-status. PD-L1 expression and TMB exhibited marked spatial heterogeneity between baseline primary and metastatic tumors (61% and 69% concordance), and temporal heterogeneity between tumors before and after chemotherapy (57%-63% and 73%-75% concordance). PD-L1 expression and TMB were not significantly associated with overall survival.

CONCLUSIONS

PD-L1 expression and TMB exhibit marked spatial and temporal heterogeneity in GEA. This heterogeneity should be considered when obtaining tumor samples for molecular testing and when deciding whether ICI therapy is appropriate.See related commentary by Klempner et al., p. 6401.

Personalized Antibodies for Gastroesophageal Adenocarcinoma (PANGEA): A Phase II Study Evaluating an Individualized Treatment Strategy for Metastatic Disease

The one-year and median overall survival (mOS) rates of advanced gastroesophageal adenocarcinomas (GEA) are ∼50% and <12 months, respectively. Baseline spatial and temporal molecular heterogeneity of targetable alterations may be a cause of failure of targeted/immunooncologic therapies. This heterogeneity, coupled with infrequent incidence of some biomarkers, has resulted in stalled therapeutic progress. We hypothesized that a personalized treatment strategy, applied at first diagnosis then serially over up to three treatment lines using monoclonal antibodies combined with optimally sequenced chemotherapy, could contend with these hurdles. This was tested using a novel clinical expansion-platform type II design with a survival primary endpoint. Of 68 patients by intention-to-treat, the one-year survival rate was 66% and mOS was 15.7 months, meeting the primary efficacy endpoint (one-sided P = 0.0024). First-line response rate (74%), disease control rate (99%), and median progression-free survival (8.2 months) were superior to historical controls. The PANGEA strategy led to improved outcomes warranting a larger randomized study. SIGNIFICANCE: This study highlights excellent outcomes achieved by individually optimizing chemotherapy, biomarker profiling, and matching of targeted therapies at baseline and over time for GEA. Testing a predefined treatment strategy resulted in improved outcomes versus historical controls. Therapeutic resistance observed in correlative analyses suggests that dual targeted inhibition may be beneficial.This article is highlighted in the In This Issue feature, p. 211.

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.

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.

Obtaining Knowledge in Pathology Reports Through a Natural Language Processing Approach With Classification, Named-Entity Recognition, and Relation-Extraction Heuristics

PURPOSE

Robust institutional tumor banks depend on continuous sample curation or else subsequent biopsy or resection specimens are overlooked after initial enrollment. Curation automation is hindered by semistructured free-text clinical pathology notes, which complicate data abstraction. Our motivation is to develop a natural language processing method that dynamically identifies existing pathology specimen elements necessary for locating specimens for future use in a manner that can be re-implemented by other institutions.

PATIENTS AND METHODS

Pathology reports from patients with gastroesophageal cancer enrolled in The University of Chicago GI oncology tumor bank were used to train and validate a novel composite natural language processing-based pipeline with a supervised machine learning classification step to separate notes into internal (primary review) and external (consultation) reports; a named-entity recognition step to obtain label (accession number), location, date, and sublabels (block identifiers); and a results proofreading step.

RESULTS

We analyzed 188 pathology reports, including 82 internal reports and 106 external consult reports, and successfully extracted named entities grouped as sample information (label, date, location). Our approach identified up to 24 additional unique samples in external consult notes that could have been overlooked. Our classification model obtained 100% accuracy on the basis of 10-fold cross-validation. Precision, recall, and F1 for class-specific named-entity recognition models show strong performance.

CONCLUSION

Through a combination of natural language processing and machine learning, we devised a re-implementable and automated approach that can accurately extract specimen attributes from semistructured pathology notes to dynamically populate a tumor registry.

Association of high TUBB3 with resistance to adjuvant docetaxel-based chemotherapy in gastric cancer: translational study of ITACA-S

BACKGROUND

No predictive markers for chemotherapy activity have been validated in gastric cancer (GC). The potential value of class III β-tubulin (TUBB3) as biomarker for prognosis and resistance to taxane-based therapy was reported.

METHODS

We analyzed GC samples of patients enrolled in the Intergroup Trial of Adjuvant Chemotherapy in Adenocarcinoma of the Stomach (ITACA-S), a randomized adjuvant study comparing 5-fluorouracil/leucovorin (5-FU/LV) and docetaxel-based sequential chemotherapy. TUBB3 was quantitated by selected reaction monitoring mass spectrometry and patients were stratified using a threshold of 750 attomoles per microgram (amol/µg). Cox proportional modeling and Kaplan-Meier survival analysis were used to assess the impact of TUBB3 expression on overall survival (OS) and disease-free survival.

RESULTS

Patients with TUBB3 protein levels >750 and <750 amol/µg were 21.9% and 78.1%, respectively, and were well-balanced between treatment arms. TUBB3 protein levels were not prognostic. Whereas no survival differences according to the 2 arms were observed in the subgroup with low TUBB3 expression (5-year OS 47% vs 40%; p = 0.44), patients with high TUBB3 had a clinically meaningful poorer OS when receiving docetaxel-based versus 5-FU/LV chemotherapy (5-year OS 31% vs 54%; p = 0.09), with a statistically significant interaction between TUBB3 and treatment (p = 0.049).

CONCLUSIONS

The quantification of TUBB3 might be considered as a negative predictive biomarker of benefit from taxane-based therapy in GC. Studies are needed to evaluate its role in the neoadjuvant setting.

Phase I Escalation and Expansion Study of Bemarituzumab (FPA144) in Patients With Advanced Solid Tumors and FGFR2b-Selected Gastroesophageal Adenocarcinoma

PURPOSE

To evaluate the safety, pharmacokinetics, and preliminary activity of bemarituzumab in patients with FGFR2b-overexpressing gastric and gastroesophageal junction adenocarcinoma (GEA).

PATIENTS AND METHODS

FPA144-001 was a phase I, open-label, multicenter trial consisting of the following 3 parts: part 1a involved dose escalation in patients with recurrent solid tumors at doses ranging from 0.3 to 15 mg/kg; part 1b involved dose escalation in patients with advanced-stage GEA; and part 2 involved dose expansion in patients with advanced-stage GEA that overexpressed FGFR2b at various levels (4 cohorts; high, medium, low, and no FGFR2b overexpression) and 1 cohort of patients with FGFR2b-overexpressing advanced-stage bladder cancer.

RESULTS

Seventy-nine patients were enrolled; 19 were enrolled in part 1a, 8 in part 1b, and 52 in part 2. No dose-limiting toxicities were reported, and the recommended dose was identified as 15 mg/kg every 2 weeks based on safety, tolerability, pharmacokinetic parameters, and clinical activity. The most frequent treatment-related adverse events (TRAEs) were fatigue (17.7%), nausea (11.4%), and dry eye (10.1%). Grade 3 TRAEs included nausea (2 patients) and anemia, neutropenia, increased AST, increased alkaline phosphatase, vomiting, and an infusion reaction (1 patient each). Three (10.7%) of 28 patients assigned to a cohort receiving a dose of ≥ 10 mg/kg every 2 weeks for ≥ 70 days reported reversible grade 2 corneal TRAEs. No TRAEs of grade ≥ 4 were reported. Five (17.9%; 95% CI, 6.1% to 36.9%) of 28 patients with high FGFR2b-overexpressing GEA had a confirmed partial response.

CONCLUSION

Overall, bemarituzumab seems to be well tolerated and demonstrated single-agent activity as late-line therapy in patients with advanced-stage GEA. Bemarituzumab is currently being evaluated in combination with chemotherapy in a phase III trial as front-line therapy for patients with high FGFR2b-overexpressing advanced-stage GEA.

Evaluation of the Association of Perioperative UGT1A1 Genotype-Dosed gFOLFIRINOX With Margin-Negative Resection Rates and Pathologic Response Grades Among Patients With Locally Advanced Gastroesophageal Adenocarcinoma: A Phase 2 Clinical Trial

IMPORTANCE

Patients with locally advanced gastroesophageal adenocarcinoma (ie, stage ≥T3 and/or node positive) have high rates of recurrence despite surgery and adjunctive perioperative therapies, which also have high toxicity profiles. Evaluation of pharmacogenomically dosed perioperative gFOLFIRINOX (fluorouracil, leucovorin, oxaliplatin, and UGT1A1 genotype-directed irinotecan) to optimize efficacy while limiting toxic effects may have value.

OBJECTIVE

To evaluate the coprimary end points of margin-negative (R0) resection rates and pathologic response grades (PRGs) of gFOLFIRINOX therapy among patients with locally advanced gastroesophageal adenocarcinoma.

DESIGN, SETTING, AND PARTICIPANTS

This single-group phase 2 trial, conducted at 2 academic medical centers from February 2014 to March 2019, enrolled 36 evaluable patients with locally advanced adenocarcinoma of the esophagus, gastroesophageal junction, and gastric body. Data analysis was conducted in May 2019.

INTERVENTIONS

Patients received biweekly gFOLFIRINOX (fluorouracil, 2400 mg/m2 over 46 hours; oxaliplatin, 85 mg/m2; irinotecan, 180 mg/m2 for UGT1A1 genotype 6/6, 135 mg/m2 for UGT1A1 genotype 6/7, or 90 mg/m2 for UGT1A1 genotype 7/7; and prophylactic peg-filgastrim, 6 mg) for 4 cycles before and after surgery. Patients with tumors positive for ERBB2 also received trastuzumab (6-mg/kg loading dose, then 4 mg/kg).

MAIN OUTCOMES AND MEASURES

Margin-negative resection rate and PRG.

RESULTS

A total of 36 evaluable patients (27 [78%] men; median [range] age, 66 [27-85] years; 10 [28%] with gastric body cancer; 24 [67%] with intestinal-type tumors; 6 [17%] with ERBB2-positive tumors; 19 [53%] with UGT1A1 genotype 6/6; 16 [44%] with genotype 6/7; and 1 [3%] with genotype 7/7) were enrolled. Of these, 35 (97%) underwent surgery; 1 patient (3%) died after completing neoadjuvant chemotherapy while awaiting surgery. Overall, R0 resection was achieved in 33 of 36 patients (92%); 2 patients (6%) with linitis plastica achieved R1 resection. Pathologic response grades 1, 2, and 3 occurred in 13 patients (36%), 9 patients (25%), and 14 patients (39%), respectively, and PRG 1 was observed in 11 of 24 intestinal-type tumors (46%). Median disease-free survival was 30.1 months (95% CI, 15.0 months to not reached), and median overall survival was not reached (95% CI, 8.3 months to not reached). There were no differences in outcomes by UGT1A1 genotype group. A total of 38 patients, including 2 (5%) with antral tumors, were evaluable for toxic effects. Grade 3 or higher adverse events occurring in 5% or more of patients during the perioperative cycles included diarrhea (7 patients [18%]; 3 of 19 patients [16%] with genotype 6/6; 2 of 16 patients [13%] with genotype 6/7; 2 of 3 patients [67%] with genotype 7/7), anemia (2 patients [5%]), vomiting (2 patients [5%]), and nausea (2 patients [5%]).

CONCLUSIONS AND RELEVANCE

In this study, perioperative pharmacogenomically dosed gFOLFIRINOX was feasible, providing downstaging with PRG 1 in more than one-third of patients and an R0 resection rate in 92% of patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02366819.

Clinical Assessment of 5-Fluorouracil/Leucovorin, Nab-Paclitaxel, and Irinotecan (FOLFIRABRAX) in Untreated Patients with Gastrointestinal Cancer Using UGT1A1 Genotype-Guided Dosing

PURPOSE

5-Fluorouracil (5-FU)/leucovorin, irinotecan, and nab-paclitaxel are all active agents in gastrointestinal cancers; the combination, FOLFIRABRAX, has not been previously evaluated. UDP Glucuronosyltransferase 1A1 (UGT1A1) clears SN-38, the active metabolite of irinotecan. UGT1A1*28 polymorphism reduces UGT1A1 enzymatic activity and predisposes to toxicity. We performed a trial to assess the safety and tolerability of FOLFIRABRAX with UGT1A1 genotype-guided dosing of irinotecan.

PATIENTS AND METHODS

Patients with previously untreated, advanced gastrointestinal cancers received FOLFIRABRAX with prophylactic pegfilgrastim every 14 days. UGT1A1 *1/*1, *1/*28, and *28/*28 patients received initial irinotecan doses of 180, 135, and 90 mg/m2, respectively. 5-FU 2,400 mg/m2 over 46 hours, leucovorin 400 mg/m2, and nab-paclitaxel 125 mg/m2 were administered. Doses were deemed tolerable if the dose-limiting toxicity (DLT) rate during cycle 1 was ≤35% in each genotype group. DLTs were monitored using a sequential procedure.

RESULTS

Fifty patients enrolled, 30 pancreatic, 9 biliary tract, 6 gastroesophageal, and 5 others. DLTs occurred in 5 of 23 (22%) *1/*1 patients, 1 of 19 (5%) *1/*28 patients, and 0 of 7 *28/*28 patients. DLTs were all grade 3: diarrhea (3 patients), nausea (2 patients), and febrile neutropenia (1 patient). The overall response rate was 31%. Response rates in pancreatic, gastroesophageal, and biliary tract cancers were 34%, 50%, and 11%, respectively. Eighteen patients (36%) received therapy for at least 24 weeks.

CONCLUSIONS

FOLFIRABRAX with genotype-guided dosing of irinotecan is tolerable in patients with advanced gastrointestinal cancer and UGT1A1*1*1 or UGT1A1*1*28 genotypes. Too few *28/*28 patients were enrolled to provide conclusive results. Responses occurred across multiple tumor types.

Validation of Microsatellite Instability Detection Using a Comprehensive Plasma-Based Genotyping Panel

PURPOSE

To analytically and clinically validate microsatellite instability (MSI) detection using cell-free DNA (cfDNA) sequencing.

EXPERIMENTAL DESIGN

Pan-cancer MSI detection using Guardant360 was analytically validated according to established guidelines and clinically validated using 1,145 cfDNA samples for which tissue MSI status based on standard-of-care tissue testing was available. The landscape of cfDNA-based MSI across solid tumor types was investigated in a cohort of 28,459 clinical plasma samples. Clinical outcomes for 16 patients with cfDNA MSI-H gastric cancer treated with immunotherapy were evaluated.

RESULTS

cfDNA MSI evaluation was shown to have high specificity, precision, and sensitivity, with a limit of detection of 0.1% tumor content. In evaluable patients, cfDNA testing accurately detected 87% (71/82) of tissue MSI-H and 99.5% of tissue microsatellite stable (863/867) for an overall accuracy of 98.4% (934/949) and a positive predictive value of 95% (71/75). Concordance of cfDNA MSI with tissue PCR and next-generation sequencing was significantly higher than IHC. Prevalence of cfDNA MSI for major cancer types was consistent with those reported for tissue. Finally, robust clinical activity of immunotherapy treatment was seen in patients with advanced gastric cancer positive for MSI by cfDNA, with 63% (10/16) of patients achieving complete or partial remission with sustained clinical benefit.

CONCLUSIONS

cfDNA-based MSI detection using Guardant360 is highly concordant with tissue-based testing, enabling highly accurate detection of MSI status concurrent with comprehensive genomic profiling and expanding access to immunotherapy for patients with advanced cancer for whom current testing practices are inadequate.See related commentary by Wang and Ajani, p. 6887.

Variety Is the Spice of Life, but Maybe Not in Gastroesophageal Adenocarcinomas

Sanchez-Vega and colleagues prospectively demonstrate that both intra- and intertumoral differential expression of the receptor tyrosine kinases HER2, EGFR, and MET dictate sensitivity to the pan-HER inhibitor afatinib in a phase II trial of trastuzumab-refractory HER2-amplified gastroesophageal adenocarcinomas. Rapid autopsy, tissue-based genomic characterization, and molecular imaging provide complementary information and may aid in selecting optimal patients for targeted monotherapy versus combination approaches in gastroesophageal adenocarcinomas.See related article by Sanchez-Vega et al., p. 199.

Safety and Efficacy of Durvalumab and Tremelimumab Alone or in Combination in Patients with Advanced Gastric and Gastroesophageal Junction Adenocarcinoma

PURPOSE

This randomized, multicenter, open-label, phase Ib/II study assessed durvalumab and tremelimumab in combination or as monotherapy for chemotherapy-refractory gastric cancer or gastroesophageal junction (GEJ) cancer.

PATIENTS AND METHODS

Second-line patients were randomized 2:2:1 to receive durvalumab plus tremelimumab (arm A), or durvalumab (arm B) or tremelimumab monotherapy (arm C), and third-line patients received durvalumab plus tremelimumab (arm D). A tumor-based IFNγ gene signature was prospectively evaluated as a potential predictive biomarker in second- and third-line patients receiving the combination (arm E). The coprimary endpoints were objective response rate and progression-free survival (PFS) rate at 6 months.

RESULTS

A total of 113 patients were treated: 6 in phase Ib and 107 (arm A, 27; arm B, 24; arm C, 12; arm D, 25; arm E, 19) in phase II. Overall response rates were 7.4%, 0%, 8.3%, 4.0%, and 15.8% in the five arms, respectively. PFS rates at 6 months were 6.1%, 0%, 20%, 15%, and 0%, and 12-month overall survival rates were 37.0%, 4.6%, 22.9%, 38.8%, and NA, respectively. Treatment-related grade 3/4 adverse events were reported in 17%, 4%, 42%, 16%, and 11% of patients, respectively.

CONCLUSIONS

Response rates were low regardless of monotherapy or combination strategies. No new safety signals were identified. Including use of a tumor-based IFNγ signature and change in baseline and on-treatment circulating tumor DNA are clinically feasible and may be novel strategies to improve treatment response in this difficult-to-treat population.

Circulating Tumor DNA Sequencing Analysis of Gastroesophageal Adenocarcinoma

PURPOSE

Gastroesophageal adenocarcinoma (GEA) has a poor prognosis and few therapeutic options. Utilizing a 73-gene plasma-based next-generation sequencing (NGS) cell-free circulating tumor DNA (ctDNA-NGS) test, we sought to evaluate the role of ctDNA-NGS in guiding clinical decision-making in GEA.

EXPERIMENTAL DESIGN

We evaluated a large cohort (n = 2,140 tests; 1,630 patients) of ctDNA-NGS results (including 369 clinically annotated patients). Patients were assessed for genomic alteration (GA) distribution and correlation with clinicopathologic characteristics and outcomes.

RESULTS

Treatment history, tumor site, and disease burden dictated tumor-DNA shedding and consequent ctDNA-NGS maximum somatic variant allele frequency. Patients with locally advanced disease having detectable ctDNA postoperatively experienced inferior median disease-free survival (P = 0.03). The genomic landscape was similar but not identical to tissue-NGS, reflecting temporospatial molecular heterogeneity, with some targetable GAs identified at higher frequency via ctDNA-NGS compared with previous primary tumor-NGS cohorts. Patients with known microsatellite instability-high (MSI-High) tumors were robustly detected with ctDNA-NGS. Predictive biomarker assessment was optimized by incorporating tissue-NGS and ctDNA-NGS assessment in a complementary manner. HER2 inhibition demonstrated a profound survival benefit in HER2-amplified patients by ctDNA-NGS and/or tissue-NGS (median overall survival, 26.3 vs. 7.4 months; P = 0.002), as did EGFR inhibition in EGFR-amplified patients (median overall survival, 21.1 vs. 14.4 months; P = 0.01).

CONCLUSIONS

ctDNA-NGS characterized GEA molecular heterogeneity and rendered important prognostic and predictive information, complementary to tissue-NGS.See related commentary by Frankell and Smyth, p. 6893.

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

Little is known about the genomic landscape of FGFR2‐altered gastroesophageal adenocarcinomas. This article attempts to bridge that gap, with a focus on concurrent alterations that may affect sensitivity to FGFR2‐directed therapies.

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.

AAA: triple adaptive Bayesian designs for the identification of optimal dose combinations in dual-agent dose finding trials

We propose a flexible design for the identification of optimal dose combinations in dual-agent dose finding clinical trials. The design is called AAA, standing for three adaptations: adaptive model selection, adaptive dose insertion and adaptive cohort division. The adaptations highlight the need and opportunity for innovation for dual-agent dose finding and are supported by the numerical results presented in the proposed simulation studies. To our knowledge, this is the first design that allows for all three adaptations at the same time. We find that AAA enhances the chance of finding the optimal dose combinations and shortens the trial duration. A clinical trial is being planned to apply the AAA design and a Web tool is being developed for both statisticians and non-statisticians.

Phase I Study of AMG 337, a Highly Selective Small-molecule MET Inhibitor, in Patients with Advanced Solid Tumors

PURPOSE

This first-in-human, open-label phase I study evaluated AMG 337, an oral, highly selective small-molecule inhibitor of MET in advanced solid tumors.Patients and Methods: Patients enrolled into dose-escalation cohorts received AMG 337 up to 400 mg once daily or up to 250 mg twice daily, following a modified 3+3+3 design. Dose expansion was conducted in MET-amplified patients at the maximum tolerated dose (MTD). Primary endpoints included assessment of adverse events (AEs), establishment of the MTD, and pharmacokinetics; clinical response was a secondary endpoint.

RESULTS

The safety analysis set included 111 patients who received ≥1 dose of AMG 337. Thirteen patients had ≥1 AE qualifying as dose-limiting toxicity. The MTD was determined to be 300 mg once daily; the MTD for twice-daily dosing was not reached. Most frequent treatment-related AEs were headache (63%) and nausea (31%). Grade ≥3 treatment-related AEs occurred in 23 patients (21%), most commonly headache (n = 6) and fatigue (n = 5). Maximum plasma concentration occurred at 3.0 hours following 300-mg once-daily dosing, indicating AMG 337 absorption soon after treatment. Objective response rate was 9.9% (11/111; 95% CI, 5.1%-17.0%) in all patients and 29.6% (8/27; 95% CI, 13.8%-50.2%) in MET-amplified patients; median (range) duration of response was 202 (51-1,430+) days in all patients and 197 (64-1,430+) days in MET-amplified patients.

CONCLUSIONS

Oral AMG 337 was tolerated with manageable toxicities, with an MTD and recommended phase II dose of 300 mg once daily. The promising response rate observed in patients with heavily pretreated MET-amplified tumors warrants further investigation.See related commentary by Ma, p. 2375.

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.

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.

Targeted Therapies for Targeted Populations: Anti-EGFR Treatment for EGFR-Amplified Gastroesophageal Adenocarcinoma

Previous anti-EGFR trials in unselected patients with gastroesophageal adenocarcinoma (GEA) were resoundingly negative. We identified EGFR amplification in 5% (19/363) of patients at the University of Chicago, including 6% (8/140) who were prospectively screened with intention-to-treat using anti-EGFR therapy. Seven patients received ≥1 dose of treatment: three first-line FOLFOX plus ABT-806, one second-line FOLFIRI plus cetuximab, and three third/fourth-line cetuximab alone. Treatment achieved objective response in 58% (4/7) and disease control in 100% (7/7) with a median progression-free survival of 10 months. Pretreatment and posttreatment tumor next-generation sequencing (NGS), serial plasma circulating tumor DNA (ctDNA) NGS, and tumor IHC/FISH for EGFR revealed preexisting and/or acquired genomic events, including EGFR-negative clones, PTEN deletion, KRAS amplification/mutation, NRAS, MYC, and HER2 amplification, and GNAS mutations serving as mechanisms of resistance. Two evaluable patients demonstrated interval increase of CD3+ infiltrate, including one who demonstrated increased NKp46+, and PD-L1 IHC expression from baseline, suggesting an immune therapeutic mechanism of action. EGFR amplification predicted benefit from anti-EGFR therapy, albeit until various resistance mechanisms emerged.Significance: This paper highlights the role of EGFR inhibitors in EGFR-amplified GEA-despite negative results in prior unselected phase III trials. Using serial ctDNA and tissue NGS, we identified mechanisms of primary and acquired resistance in all patients, as well as potential contribution of antibody-dependent cell-mediated cytotoxicity to their clinical benefit. Cancer Discov; 8(6); 696-713. ©2018 AACR.See related commentary by Strickler, p. 679This article is highlighted in the In This Issue feature, p. 663.

Novel Targeted Therapies for Esophagogastric Cancer

Gastroesophageal cancer (GEC) remains a major cause of cancer-related mortality worldwide. Although the incidence of distal gastric adenocarcinoma (GC) is declining in the United States, proximal esophagogastric junction adenocarcinoma (EGJ) is increasing in incidence. GEC, including GC and EGJ, is treated uniformly in the metastatic setting. Overall survival in the metastatic setting remains poor. Molecular characterization of GEC has identified mutations and copy number variations, along with other oncogenes, biomarkers, and immuno-oncologic checkpoints that may serve as actionable therapeutic targets. This article reviews these key aberrations, their impact on protein expression, therapeutic implications, and clinical directions within each pathway.

Rilotumumab plus epirubicin, cisplatin, and capecitabine as first-line therapy in advanced MET-positive gastric or gastro-oesophageal junction cancer (RILOMET-1): a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND

Rilotumumab is a fully human monoclonal antibody that selectively targets the ligand of the MET receptor, hepatocyte growth factor (HGF). We aimed to assess the efficacy, safety, and pharmacokinetics of rilotumumab combined with epirubicin, cisplatin, and capecitabine, and to assess potential biomarkers, in patients with advanced MET-positive gastric or gastro-oesophageal junction adenocarcinoma.

METHODS

This multicentre, randomised, double-blind, placebo-controlled, phase 3 study was done at 152 centres in 27 countries. We recruited adults (aged ≥18 years) with unresectable locally advanced or metastatic gastric or gastro-oesophageal junction adenocarcinoma, an Eastern Cooperative Oncology Group (ECOG) performance status of 0 or 1, MET-positive tumours (≥25% of tumour cells with membrane staining of ≥1+ staining intensity), and evaluable disease, who had not received previous systemic therapy. Eligible patients were randomly assigned (1:1) via a computerised voice response system to receive rilotumumab 15 mg/kg intravenously or placebo in combination with open-label chemotherapy (epirubicin 50 mg/m² intravenously; cisplatin 60 mg/m² intravenously; capecitabine 625 mg/m² orally twice daily) in 21-day cycles for up to ten cycles. After completion of chemotherapy, patients continued to receive rilotumumab or placebo monotherapy until disease progression, intolerability, withdrawal of consent, or study termination. Randomisation was stratified by disease extent and ECOG performance status. Both patients and physicians were masked to study treatment assignment. The primary endpoint was overall survival, analysed by intention to treat. We report the final analysis. This study is registered with ClinicalTrials.gov, number NCT01697072.

FINDINGS

Between Nov 7, 2012, and Nov 21, 2014, 609 patients were randomly assigned to rilotumumab plus epirubicin, cisplatin, and capecitabine (rilotumumab group; n=304) or placebo plus epirubicin, cisplatin, and capecitabine (placebo group; n=305). Study treatment was stopped early after an independent data monitoring committee found a higher number of deaths in the rilotumumab group than in the placebo group; all patients in the rilotumumab group subsequently discontinued all study treatment. Median follow-up was 7·7 months (IQR 3·6-12·0) for patients in the rilotumumab group and 9·4 months (5·3-13·1) for patients in the placebo group. Median overall survival was 8·8 months (95% CI 7·7-10·2) in the rilotumumab group compared with 10·7 months (9·6-12·4) in the placebo group (stratified hazard ratio 1·34, 95% CI 1·10-1·63; p=0·003). The most common grade 3 or worse adverse events in the rilotumumab and placebo groups were neutropenia (86 [29%] of 298 patients vs 97 [32%] of 299 patients), anaemia (37 [12%] vs 43 [14%]), and fatigue (30 [10%] vs 35 [12%]). The frequency of serious adverse events was similar in the rilotumumab and placebo groups (142 [48%] vs 149 [50%]). More deaths due to adverse events occurred in the rilotumumab group than the placebo group (42 [14%] vs 31 [10%]). In the rilotumumab group, 33 (11%) of 298 patients had fatal adverse events due to disease progression, and nine (3%) had fatal events not due to disease progression. In the placebo group, 23 (8%) of 299 patients had fatal adverse events due to disease progression, and eight (3%) had fatal events not due to disease progression.

INTERPRETATION

Ligand-blocking inhibition of the MET pathway with rilotumumab is not effective in improving clinical outcomes in patients with MET-positive gastric or gastro-oesophageal adenocarcinoma.

FUNDING

Amgen.

Update on Gastroesophageal Adenocarcinoma Targeted Therapies

Gastroesophageal cancer (GEC) remains a major cause of cancer-related mortality worldwide. Although the incidence of distal gastric adenocarcinoma (GC) is declining in the United States, proximal esophagogastric junction adenocarcinoma (EGJ) incidence is rising. GC and EGJ, together, are treated uniformly in the metastatic setting as GEC. Overall survival in the metastatic setting remains poor, with few molecular targeted approaches having been successfully incorporated into routine care to date-only first-line anti-HER2 therapy for ERBB2 amplification and second-line anti-VEGFR2 therapy. This article reviews aberrations in epidermal growth factor receptor, MET, and ERBB2, their therapeutic implications, and future directions in targeting these pathways.

Quantitative proteomic analysis of HER2 expression in the selection of gastric cancer patients for trastuzumab treatment

Background

A wide range of response rates have been reported in HER2-positive gastric cancer (GC) patients treated with trastuzumab. Other HER2-targeted therapies for GC have yet to show efficacy in clinical trials. These findings raise question about the ability of standard HER2 diagnostics to accurately distinguish between GC patients who would and would not benefit from anti-HER2 therapies.

Patients and methods

GC patients (n = 237), including a subset from the Trastuzumab in GC (ToGA) trial were divided into three groups based on HER2 status and history of treatment with standard chemotherapy or chemotherapy plus trastuzumab. We applied mass spectrometry-based proteomic analysis to quantify HER2 protein expression in formalin-fixed tumor samples. Using HER2 expression as a continuous variable, we defined a predictive protein level cutoff to identify which patients would benefit from trastuzumab. We compared quantitated protein level with clinical outcome and HER2 status as determined by conventional HER2 diagnostics.

Results

Quantitative proteomics detected a 115-fold range of HER2 protein expression among patients diagnosed as HER2 positive by standard methods. A protein level of 1825 amol/µg was predicted to determine benefit from the addition of trastuzumab to chemotherapy. Trastuzumab treated patients with HER2 protein levels above this cutoff had twice the median overall survival (OS) of their counterparts below the cutoff (35.0 versus 17.5 months, P = 0.011). Conversely, trastuzumab-treated patients with HER2 levels below the cutoff had outcomes similar to HER2-positive patients treated with chemotherapy. (Progression-free survival = 7.0 versus 6.5 months: P = 0.504; OS = 17.5 versus 12.6 months: P = 0.520). HER2 levels were not prognostic for response to chemotherapy.

Conclusions

Proteomic analysis of HER2 expression demonstrated a quantitative cutoff that improves selection of GC patients for trastuzumab as compared with current diagnostic methods.

MET tyrosine kinase receptor expression and amplification as prognostic biomarkers of survival in gastroesophageal adenocarcinoma

BACKGROUND

MET gene amplification and Met protein overexpression may be associated with a poor prognosis. The MET/Met status is typically determined with fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), respectively. Targeted proteomics uses mass spectrometry–based selected reaction monitoring (SRM) to accurately quantitate Met expression. FISH, IHC, and SRM analyses were compared to characterize the prognostic value of MET/Met in gastroesophageal adenocarcinoma (GEC).

METHODS

Samples from 447 GEC patients were analyzed for MET gene amplification (FISH) and Met protein expression (IHC and SRM). Cox proportional hazards models and Kaplan‐Meier estimates were applied to explore relations between Met, overall survival (OS), and clinical/pathological characteristics. Spearman's rank coefficient was used to assess the correlation between parameters.

RESULTS

Patients with MET‐amplified tumors had worse OS when: the MET/centromere enumeration probe for chromosome 7 FISH ratio was ≥ 2 (hazard ratio [HR], 3.13; 95% confidence interval [CI], 1.84‐5.33), the MET gene copy number was ≥5 (HR, 2.51; 95% CI, 1.45‐4.34), or ≥ 10% of the cells had ≥15 copies (HR, 4.28; 95% CI, 2.18‐8.39). Similar observations were made with Met protein overexpression by IHC (≥1 + intensity in ≥ 25% of the tumor cell membrane: HR, 1.39; 95% CI, 1.04‐1.86) or SRM (≥400 amol/μg: HR, 1.76; 95% CI, 1.06‐2.90). A significant correlation was observed between MET FISH/Met IHC, MET FISH/Met SRM, and Met IHC/Met SRM; only MET FISH and Met SRM were independent negative prognostic biomarkers in multivariate analyses.

CONCLUSIONS

MET amplification and overexpression, assessed by multiple methods, were associated with a worse prognosis in univariate analyses. However, only MET amplification by FISH and Met expression by SRM were independent prognostic biomarkers. Compared with IHC, SRM may provide an added benefit for informed decisions about Met‐targeted therapy. Cancer 2017;123:1061–70. © 2016 American Cancer Society.

In a large study, MET gene amplification, Met protein overexpression, or both, as assessed by various assays, are associated with a poor prognosis in univariate analyses. However, only MET amplification by fluorescence in situ hybridization and Met expression by selected reaction monitoring mass spectrometry are independent prognostic biomarkers; compared with immunohistochemistry, selected reaction monitoring may provide an added benefit for informed decisions about Met‐targeted therapy.

A subgroup cluster-based Bayesian adaptive design for precision medicine

In precision medicine, a patient is treated with targeted therapies that are predicted to be effective based on the patient's baseline characteristics such as biomarker profiles. Oftentimes, patient subgroups are unknown and must be learned through inference using observed data. We present SCUBA, a Subgroup ClUster-based Bayesian Adaptive design aiming to fulfill two simultaneous goals in a clinical trial, 1) to treatments enrich the allocation of each subgroup of patients to their precision and desirable treatments and 2) to report multiple subgroup-treatment pairs (STPs). Using random partitions and semiparametric Bayesian models, SCUBA provides coherent and probabilistic assessment of potential patient subgroups and their associated targeted therapies. Each STP can then be used for future confirmatory studies for regulatory approval. Through extensive simulation studies, we present an application of SCUBA to an innovative clinical trial in gastroesphogeal cancer.

Mass-spectrometry-based quantitation of Her2 in gastroesophageal tumor tissue: comparison to IHC and FISH

BACKGROUND

Trastuzumab has shown a survival benefit in cases of Her2-positive gastroesophageal cancer (GEC). Immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) currently determine eligibility for trastuzumab-based therapy. However, these low-throughput assays often produce discordant or equivocal results.

METHODS

We developed a targeted proteomic assay based on selected reaction monitoring mass spectrometry (SRM-MS) and quantified levels (amol/μg) of Her2-SRM protein in cell lines (n = 27) and GEC tissues (n = 139). We compared Her2-SRM protein expression with IHC/FISH, seeking to determine optimal SRM protein expression cutoffs in order to identify HER2 gene amplification.

RESULTS

After demonstrating assay development, precision, and stability, Her2-SRM protein measurement was observed to be highly concordant with the HER2/CEP17 ratio, particularly in a multivariate regression model adjusted for SRM expression of the covariates Met, Egfr, Her3, and HER2 heterogeneity, as well as their interactions (cell lines r (2) = 0.9842; FFPE r (2) = 0.7643). In GEC tissues, Her2-SRM protein was detected at any level in 71.2 % of cases. ROC curves demonstrated that Her2-SRM protein levels have a high specificity (100 %) at an upper-level cutoff of >750 amol/µg and sensitivity of 75 % at a lower-level cutoff of <450 amol/μg for identifying HER2 FISH-amplified tumors. An "equivocal zone" of 450-750 amol/µg of Her2-SRM protein was analogous to IHC2+ but represented fewer cases (9-16 % of cases versus 36-41 %).

CONCLUSIONS

Compared to IHC, targeted SRM-Her2 proteomics provided more objective and quantitative Her2 expression with excellent HER2/CEP17 FISH correlation and fewer equivocal cases. Along with its multiplex capability for other relevant oncoproteins, these results demonstrate a refined HER2 protein expression assay for clinical application.

A phase 1 clinical trial of ASG-5ME, a novel drug-antibody conjugate targeting SLC44A4, in patients with advanced pancreatic and gastric cancers

Purpose ASG-5ME is an antibody-drug conjugate (ADC) targeting SLC44A4, a novel cell surface target expressed on most pancreatic and gastric cancers. This first-in-human study of ASG-5ME evaluated safety, pharmacokinetics, and preliminary activity of ASG-5ME in advanced pancreatic and gastric cancer patients. Experimental Design This phase 1, dose-escalation, multicenter study determined the maximum tolerated dose (MTD) and assessed safety and antitumor activity. The dose-escalation portion enrolled metastatic pancreatic adenocarcinoma patients; gastric adenocarcinoma patients were included in the dose-expansion portion. Patients received ASG-5ME intravenously on Days 1, 8, and 15 of 28-day cycles. Results Thirty-five pancreatic cancer patients (median age 63 years; performance status 0 [40 %] or 1 [60 %]) were treated at doses of 0.3 to 1.5 mg/kg (median duration 8.1 weeks). The MTD was exceeded at 1.5 mg/kg (n = 7) with 1 dose-limiting toxicity (DLT) of Grade 4 gastrointestinal hemorrhage. Four patients experienced non-DLT Grade 3 or 4 neutropenia. Fifteen gastric cancer patients (median age 59 years; performance status 0 [33 %] or 1 [67 %]) were treated at the identified MTD of 1.2 mg/kg (median duration 8.7 weeks). Common drug-related adverse events included fatigue (29 %), nausea (23 %), and vomiting (23 %) for pancreatic cancer patients and fatigue (33 %) and decreased appetite (33 %) for gastric cancer patients. Best clinical response was 1 partial response in each cohort. Disease-control rates of 33 % (pancreatic) and 47 % (gastric) were observed at the MTD. All patient biopsies (23 pancreatic, 15 gastric) expressed the SLC44A4 antigen. Conclusions ASG-5ME treatment was generally well tolerated with limited evidence of antitumor activity.

Randomized Phase Ib/II Study of Gemcitabine Plus Placebo or Vismodegib, a Hedgehog Pathway Inhibitor, in Patients With Metastatic Pancreatic Cancer

PURPOSE

Sonic hedgehog (SHH), an activating ligand of smoothened (SMO), is overexpressed in > 70% of pancreatic cancers (PCs). We investigated the impact of vismodegib, an SHH antagonist, plus gemcitabine (GV) or gemcitabine plus placebo (GP) in a multicenter phase Ib/randomized phase II trial and preclinical PC models.

PATIENTS AND METHODS

Patients with PC not amenable to curative therapy who had received no prior therapy for metastatic disease and had Karnofsky performance score ≥ 80 were enrolled. Patients were randomly assigned in a one-to-one ratio to GV or GP. The primary end point was progression-free-survival (PFS). Exploratory correlative studies included serial SHH serum levels and contrast perfusion computed tomography imaging. To further investigate putative biologic mechanisms of SMO inhibition, two autochthonous pancreatic cancer models (Kras(G12D); p16/p19(fl/fl); Pdx1-Cre and Kras(G12D); p53(R270H/wt); Pdx1-Cre) were studied.

RESULTS

No safety issues were identified in the phase Ib portion (n = 7), and the phase II study enrolled 106 evaluable patients (n = 53 in each arm). Median PFS was 4.0 and 2.5 months for GV and GP arms, respectively (95% CI, 2.5 to 5.3 and 1.9 to 3.8, respectively; adjusted hazard ratio, 0.81; 95% CI, 0.54 to 1.21; P = .30). Median overall survival (OS) was 6.9 and 6.1 months for GV and GP arms, respectively (95% CI, 5.8 to 8.0 and 5.0 to 8.0, respectively; adjusted hazard ratio, 1.04; 95% CI, 0.69 to 1.58; P = .84). Response rates were not significantly different. There were no significant associations between correlative markers and overall response rate, PFS, or OS. Preclinical trials revealed no significant differences with vismodegib in drug delivery, tumor growth rate, or OS in either model.

CONCLUSION

The addition of vismodegib to gemcitabine in an unselected cohort did not improve overall response rate, PFS, or OS in patients with metastatic PC. Our preclinical and clinical results revealed no statistically significant differences with respect to drug delivery or treatment efficacy using vismodegib.

Acquisition of Portal Venous Circulating Tumor Cells From Patients With Pancreaticobiliary Cancers by Endoscopic Ultrasound

BACKGROUND & AIMS

Tumor cells circulate in low numbers in peripheral blood; their detection is used predominantly in metastatic disease. We evaluated the feasibility and safety of sampling portal venous blood via endoscopic ultrasound (EUS) to count portal venous circulating tumor cells (CTCs), compared with paired peripheral CTCs, in patients with pancreaticobiliary cancers (PBCs).

METHODS

In a single-center cohort study, we evaluated 18 patients with suspected PBCs. Under EUS guidance, a 19-gauge EUS fine needle was advanced transhepatically into the portal vein and as many as four 7.5-mL aliquots of blood were aspirated. Paired peripheral blood samples were obtained. Epithelial-derived CTCs were sorted magnetically based on expression of epithelial cell adhesion molecules; only those with a proper morphology and found to be CD45 negative and positive for cytokeratins 8, 18, and/or 19 and 4',6-diamidino-2-phenylindole were considered to be CTCs. For 5 samples, CTCs also were isolated by flow cytometry and based on CD45 depletion. ImageStream was used to determine the relative protein levels of P16, SMAD4, and P53. DNA was extracted from CTCs for sequencing of select KRAS codons.

RESULTS

There were no complications from portal vein blood acquisition. We detected CTCs in portal vein samples from all 18 patients (100%) vs peripheral blood samples from only 4 patients (22.2%). Patients with confirmed PBCs had a mean of 118.4 ± 36.8 CTCs/7.5 mL portal vein blood, compared with a mean of 0.8 ± 0.4 CTCs/7.5 mL peripheral blood (P < .01). The 9 patients with nonmetastatic, resectable, or borderline-resectable PBCs had a mean of 83.2 CTCs/7.5 mL portal vein blood (median, 62.0 CTCs/7.5 mL portal vein blood). In a selected patient, portal vein CTCs were found to carry the same mutations as those detected in a metastatic lymph node and expressed similar levels of P16, SMAD4, and P53 proteins.

CONCLUSIONS

It is feasible and safe to collect portal venous blood from patients undergoing EUS. We identified CTCs in all portal vein blood samples from patients with PBCs, but less than 25% of peripheral blood samples. Portal vein CTCs can be used for molecular characterization of PBCs and share features of metastatic tissue. This technique might be used to study the pathogenesis and progression of PBCs, as well as a diagnostic or prognostic tool to stratify risk of cancer recurrence or developing metastases.

Next-generation clinical trials: Novel strategies to address the challenge of tumor molecular heterogeneity

The promise of 'personalized cancer care' with therapies toward specific molecular aberrations has potential to improve outcomes. However, there is recognized heterogeneity within any given tumor-type from patient to patient (inter-patient heterogeneity), and within an individual (intra-patient heterogeneity) as demonstrated by molecular evolution through space (primary tumor to metastasis) and time (after therapy). These issues have become hurdles to advancing cancer treatment outcomes with novel molecularly targeted agents. Classic trial design paradigms are challenged by heterogeneity, as they are unable to test targeted therapeutics against low frequency genomic 'oncogenic driver' aberrations with adequate power. Usual accrual difficulties to clinical trials are exacerbated by low frequencies of any given molecular driver. To address these challenges, there is need for innovative clinical trial designs and strategies implementing novel diagnostic biomarker technologies to account for inter-patient molecular diversity and scarce tissue for analysis. Importantly, there is also need for pre-defined treatment priority algorithms given numerous aberrations commonly observed within any one individual sample. Access to multiple available therapeutic agents simultaneously is crucial. Finally intra-patient heterogeneity through time may be addressed by serial biomarker assessment at the time of tumor progression. This report discusses various 'next-generation' biomarker-driven trial designs and their potentials and limitations to tackle these recognized molecular heterogeneity challenges. Regulatory hurdles, with respect to drug and companion diagnostic development and approval, are considered. Focus is on the 'Expansion Platform Design Types I and II', the latter demonstrated with a first example, 'PANGEA: Personalized Anti-Neoplastics for Gastro-Esophageal Adenocarcinoma'. Applying integral medium-throughput genomic and proteomic assays along with a practical biomarker assessment and treatment algorithm, 'PANGEA' attempts to address the problem of heterogeneity towards successful implementation of molecularly targeted therapies.