Co-clinical Trial of Novel Bispecific Anti-HER2 Antibody Zanidatamab in Patient-Derived Xenografts.

Zanidatamab is a bispecific human epidermal growth factor receptor 2 (HER2)-targeted antibody that has demonstrated antitumor activity in a broad range of HER2-amplified/expressing solid tumors. We determined the antitumor activity of zanidatamab in patient-derived xenograft (PDX) models developed from pretreatment or postprogression biopsies on the first-in-human zanidatamab phase I study (NCT02892123). Of 36 tumors implanted, 19 PDX models were established (52.7% take rate) from 17 patients. Established PDXs represented a broad range of HER2-expressing cancers, and in vivo testing demonstrated an association between antitumor activity in PDXs and matched patients in 7 of 8 co-clinical models tested. We also identified amplification of MET as a potential mechanism of acquired resistance to zanidatamab and demonstrated that MET inhibitors have single-agent activity and can enhance zanidatamab activity in vitro and in vivo. These findings provide evidence that PDXs can be developed from pretreatment biopsies in clinical trials and may provide insight into mechanisms of resistance. SIGNIFICANCE: We demonstrate that PDXs can be developed from pretreatment and postprogression biopsies in clinical trials and may represent a powerful preclinical tool. We identified amplification of MET as a potential mechanism of acquired resistance to the HER2 inhibitor zanidatamab and MET inhibitors alone and in combination as a therapeutic strategy. This article is featured in Selected Articles from This Issue, p. 695.

Convergent MAPK pathway alterations mediate acquired resistance to FGFR inhibitors in FGFR2 fusion-positive cholangiocarcinoma.

BACKGROUND & AIMS: There is a knowledge gap in understanding mechanisms of resistance to fibroblast growth factor receptor (FGFR) inhibitors (FGFRi) and a need for novel therapeutic strategies to overcome it. We investigated mechanisms of acquired resistance to FGFRi in patients with FGFR2-fusion-positive cholangiocarcinoma (CCA). METHODS: A retrospective analysis of patients who received FGFRi therapy and underwent tumor and/or cell-free DNA analysis, before and after treatment, was performed. Longitudinal circulating tumor DNA samples from a cohort of patients in the phase I trial of futibatinib (NCT02052778) were assessed. FGFR2-BICC1 fusion cell lines were developed and secondary acquired resistance mutations in the mitogen-activated protein kinase (MAPK) pathway were introduced to assess their effect on sensitivity to FGFRi in vitro. RESULTS: On retrospective analysis of 17 patients with repeat sequencing following FGFRi treatment, new FGFR2 mutations were detected in 11 (64.7%) and new alterations in MAPK pathway genes in nine (52.9%) patients, with seven (41.2%) patients developing new alterations in both the FGFR2 and MAPK pathways. In serially collected plasma samples, a patient treated with an irreversible FGFRi tested positive for previously undetected BRAF V600E, NRAS Q61K, NRAS G12C, NRAS G13D and KRAS G12K mutations upon progression. Introduction of a FGFR2-BICC1 fusion into biliary tract cells in vitro sensitized the cells to FGFRi, while concomitant KRAS G12D or BRAF V600E conferred resistance. MEK inhibition was synergistic with FGFRi in vitro. In an in vivo animal model, the combination had antitumor activity in FGFR2 fusions but was not able to overcome KRAS-mediated FGFRi resistance. CONCLUSIONS: These findings suggest convergent genomic evolution in the MAPK pathway may be a potential mechanism of acquired resistance to FGFRi. CLINICAL TRIAL NUMBER: NCT02052778. IMPACT AND IMPLICATIONS: We evaluated tumors and plasma from patients who previously received inhibitors of fibroblast growth factor receptor (FGFR), an important receptor that plays a role in cancer cell growth, especially in tumors with abnormalities in this gene, such as FGFR fusions, where the FGFR gene is fused to another gene, leading to activation of cancer cell growth. We found that patients treated with FGFR inhibitors may develop mutations in other genes such as KRAS, and this can confer resistance to FGFR inhibitors. These findings have several implications for patients with FGFR2 fusion-positive tumors and provide mechanistic insight into emerging MAPK pathway alterations which may serve as a therapeutic vulnerability in the setting of acquired resistance to FGFRi.

Efficacy of futibatinib, an irreversible fibroblast growth factor receptor inhibitor, in FGFR-altered breast cancer.

Several alterations in fibroblast growth factor receptor (FGFR) genes have been found in breast cancer; however, they have not been well characterized as therapeutic targets. Futibatinib (TAS-120; Taiho) is a novel, selective, pan-FGFR inhibitor that inhibits FGFR1-4 at nanomolar concentrations. We sought to determine futibatinib's efficacy in breast cancer models. Nine breast cancer patient-derived xenografts (PDXs) with various FGFR1-4 alterations and expression levels were treated with futibatinib. Antitumor efficacy was evaluated by change in tumor volume and time to tumor doubling. Alterations indicating sensitization to futibatinib in vivo were further characterized in vitro. FGFR gene expression between patient tumors and matching PDXs was significantly correlated; however, overall PDXs had higher FGFR3-4 expression. Futibatinib inhibited tumor growth in 3 of 9 PDXs, with tumor stabilization in an FGFR2-amplified model and prolonged regression (> 110 days) in an FGFR2 Y375C mutant/amplified model. FGFR2 overexpression and, to a greater extent, FGFR2 Y375C expression in MCF10A cells enhanced cell growth and sensitivity to futibatinib. Per institutional and public databases, FGFR2 mutations and amplifications had a population frequency of 1.1%-2.6% and 1.5%-2.5%, respectively, in breast cancer patients. FGFR2 alterations in breast cancer may represent infrequent but highly promising targets for futibatinib.

Socioeconomic disparities in patients with small bowel neuroendocrine tumors.

BACKGROUND AND OBJECTIVES: Demographic and socioeconomic disparities affect cancer specific outcomes in numerous malignancies, but the impact of these for patients with small bowel neuroendocrine tumors (SBNETs) is not well understood. The primary objective was to investigate the impact of demographic and socioeconomic factors on overall survival (OS) for patients with SBNETs. METHODS: We performed a retrospective cohort study utilizing the National Cancer Database to assess patients diagnosed with SBNET between 2004 and 2015. Patients were stratified by demographics, socioeconomic factors, insurance status, and place of living. RESULTS: The 5-year OS for the entire cohort was 78.5%. The 5-year survival was worse in patients with lower income (p < 0.0001), lower education (p < 0.0001), not in proximity to a metro area (p = 0.0004), and treatment at a community cancer center (p < 0.0001). Adjusting for age and sex, factors associated with worse OS were lower income (<$38 000) (hazard ratio [HR]: 1.16, 95% confidence interval [CI]: 1.04-1.28), lower education (>20% no HSD) (HR: 1.14, 95% CI: 1.02-1.26), no insurance (HR: 1.66, 95% CI: 1.33-2.06), and not living in proximity to a metro area (HR: 1.27, 95% CI: 1.10-1.47). CONCLUSIONS: Patient demographics and socioeconomic factors play an important role in survival of patients with SBNETs, specifically proximity to a metro area, median income, education level, and type of treatment center. Strategies to improve access to care must be considered in this at-risk population.

Epigenetically upregulating TROP2 and SLFN11 enhances therapeutic efficacy of TROP2 antibody drug conjugate sacitizumab govitecan.

TROP2 antibody drug conjugates (ADCs) are under active development. We seek to determine whether we can enhance activity of TROP2 ADCs by increasing TROP2 expression. In metaplastic breast cancers (MpBC), there is limited expression of TROP2, and downregulating transcription factor ZEB1 upregulates E-cad and TROP2, thus sensitizing cancers to TROP2 ADC sacituzumab govitecan (SG). Demethylating agent decitabine decreases DNA methyltransferase expression and TROP2 promoter methylation and subsequently increases TROP2 expression. Decitabine treatment as well as overexpression of TROP2 significantly enhance SG antitumor activity. Decitabine also increases SLFN11, a biomarker of topoisomerase 1 inhibitor (TOP1) sensitivity and is synergistic with SG which has a TOP1 payload, in TROP2-expressing SLFN11-low BC cells. In conclusion, TROP2 and SLFN11 expression can be epigenetically modulated and the combination of demethylating agent decitabine with TROP2 ADCs may represent a novel therapeutic approach for tumors with low TROP2 or SLFN11 expression.

Adavosertib Enhances Antitumor Activity of Trastuzumab Deruxtecan in HER2-Expressing Cancers.

PURPOSE: Cyclin E (CCNE1) has been proposed as a biomarker of sensitivity to adavosertib, a Wee1 kinase inhibitor, and a mechanism of resistance to HER2-targeted therapy. EXPERIMENTAL DESIGN: Copy number and genomic sequencing data from The Cancer Genome Atlas and MD Anderson Cancer Center databases were analyzed to assess ERBB2 and CCNE1 expression. Molecular characteristics of tumors and patient-derived xenografts (PDX) were assessed by next-generation sequencing, whole-exome sequencing, fluorescent in situ hybridization, and IHC. In vitro, CCNE1 was overexpressed or knocked down in HER2+ cell lines to evaluate drug combination efficacy. In vivo, NSG mice bearing PDXs were subjected to combinatorial therapy with various treatment regimens, followed by tumor growth assessment. Pharmacodynamic markers in PDXs were characterized by IHC and reverse-phase protein array. RESULTS: Among several ERBB2-amplified cancers, CCNE1 co-amplification was identified (gastric 37%, endometroid 43%, and ovarian serous adenocarcinoma 41%). We hypothesized that adavosertib may enhance activity of HER2 antibody-drug conjugate trastuzumab deruxtecan (T-DXd). In vitro, sensitivity to T-DXd was decreased by cyclin E overexpression and increased by knockdown, and adavosertib was synergistic with topoisomerase I inhibitor DXd. In vivo, the T-DXd + adavosertib combination significantly increased γH2AX and antitumor activity in HER2 low, cyclin E amplified gastroesophageal cancer PDX models and prolonged event-free survival (EFS) in a HER2-overexpressing gastroesophageal cancer model. T-DXd + adavosertib treatment also increased EFS in other HER2-expressing tumor types, including a T-DXd-treated colon cancer model. CONCLUSIONS: We provide rationale for combining T-DXd with adavosertib in HER2-expressing cancers, especially with co-occuring CCNE1 amplifications. See related commentary by Rolfo et al., p. 4317.

Discordance of HER2 Expression and/or Amplification on Repeat Testing.

We sought to assess discordance of HER2 status in patients with HER2-amplified/expressing solid tumors who underwent reevaluation of HER2 status. Patients with metastatic solid tumors and HER2 expression by IHC or amplification by FISH/next-generation sequencing on local testing underwent central HER2 IHC/FISH testing with either archival or fresh biopsies and were evaluated for discordance in HER2 status. 70 patients (12 cancer types) underwent central HER2 reevaluation, including 57 (81.4%) with a new biopsy. In 30 patients with HER2 3+ on local IHC, 21 (70.0%) were 3+, 5 (16.7%) were 2+, 2 (6.7%) were 1+, and 2 (6.7%) had 0 HER2 expression on central IHC. In 15 patients whose cancers were 2+ on local IHC, 2 (13.3%) were 3+, 5 (33.3%) were 2+, 7 (46.7%) were 1+, and 1 (6.7%) had 0 HER2 expression on central IHC. HER2 discordance was seen in 16 of 52 (30.8%) of patients with HER2 overexpression/amplification who underwent a new image-guided biopsy. Discordance was observed in 10 (33.3%) of 30 patients who received intervening HER2-targeted therapy and in 6 (23.8%) of 22 patients who did not. In the 8 patients who had central HER2 assessment from the same archival block used for local testing, none were discordant. Discordance of HER2 status is common in patients with tumors previously identified as HER2-expressing, especially in patients with HER2 2+ tumors. Repeat biomarker evaluation may have value when considering HER2-targeted therapies.

A prospective feasibility study evaluating the 5x-multiplier to standardize discharge prescriptions in cancer surgery patients.

Background: We designed a prospective feasibility study to assess the 5x-multiplier (5x) calculation (eg, 3 pills in last 24 hours × 5 = 15) to standardize discharge opioid prescriptions compared to usual care. Methods: Faculty-based surgical teams volunteered for either 5x or usual care arms. Patients undergoing inpatient (≥ 48 hours) surgery and discharged by surgical teams were included. The primary end point was discharge oral morphine equivalents. Secondary end points were opioid-free discharges and 30-day refill rates. Results: Median last 24-hour oral morphine equivalents was similar between arms (7.5 mg 5x vs 10 mg usual care, P = .830). Median discharge oral morphine equivalents were less in the 5x arm (50 mg 5x vs 75 mg usual care, P < .001). Opioid-free discharges included 33.5% 5x vs 18.0% usual care arm patients (P < .001). Thirty-day refill rates were similar (15.3% 5x vs 16.5% usual care, P = .742). Conclusion: The 5x-multiplier was associated with reduced opioid prescriptions without increased refills and can be feasibly implemented across a diverse surgical practice.

Corticosteroid-Refractory Myositis After Dual BRAF and MEK Inhibition in a Patient with BRAF V600E-Mutant Metastatic Intrahepatic Cholangiocarcinoma.

Intrahepatic cholangiocarcinoma is a rare malignancy, which is rich in actionable alterations. Genomic aberrations in the mitogen-activated protein kinase (MAPK) pathway are common, and BRAF exon 15 p.V600E mutations are present in 5-7% of biliary tract cancers (BTC). Dual inhibition of BRAF and MEK has been established for BRAF-mutated melanoma and lung cancer, and recent basket trials have shown efficacy of this combination in BRAF V600E-mutant BTCs. Here, we report on a patient with BRAF exon 15 p.V600E mutant metastatic intrahepatic cholangiocarcinoma who was started on BRAF and MEK inhibition with vemurafenib and combimetinib. Shortly thereafter, he developed debilitating myositis, which was refractory to corticosteroids, requiring therapeutic plasma exchange and intravenous immunoglobulin. We also review BRAF as a target in BTCs, relevant clinical trials, and adverse events associated with BRAF and MEK inhibition.

Prognostic significance of preoperative and postoperative CA 19-9 normalization in pancreatic adenocarcinoma treated with neoadjuvant therapy or surgery first.

BACKGROUND: Normal(ization) of serum carbohydrate 19-9 (CA19-9) before/after surgery has not been compared in patients with pancreatic adenocarcinoma (PDAC) treated with neoadjuvant therapy (NT) versus surgery-first (SF). METHODS: Characteristics for patients with PDAC who underwent resection from July 2011 to October 2018 were collected. Patients with pre-/postoperative CA19-9, bilirubin <2 mg/dL, and initial CA19-9 > 1 U/ml were included. Overall survival (OS) and recurrence-free survival (RFS) were compared by pre-/postoperative CA19-9. RESULTS: In patients receiving NT, normal pre/postoperative CA19-9 ("NTnl/nl ") was associated with median RFS and OS (26 and 77mo), followed by those who normalized after surgery ("NTabnl/nl " 16 and 44mo). For SF patients, normal pre-/postoperative CA19-9 ("SFnl/nl ") was associated with median RFS and OS (115 and not estimable mo), followed by those who normalized after resection ("SFabnl/nl " 18 and 49mo). Groups "NTabnl/abnl " and "SFabnl/abnl " with elevated CA19-9 both before and after resection had the worst median RFS and OS durations. CONCLUSIONS: While a normal(ized) postoperative CA19-9 may result in similar survival as preoperative normal(ization), postoperative normalization failed to occur in nearly 30% of SF patients. NT should be considered in patients presenting with elevated CA19-9. If considering SF, ideal patients may include those with normal CA19-9 at presentation.

Prospective Implementation of Standardized Post-Hepatectomy Care Pathways to Reduce Opioid Prescription Volume after Inpatient Surgery.

BACKGROUND: Among the goals of prospectively implemented post-hepatectomy care pathways was a focus on patient-centric opioid reduction. We sought to evaluate the impact of pathway implementation on opioid volumes in the last 24-hour period and discharge prescriptions. STUDY DESIGN: This is a retrospective cohort study comparing a prospective cohort ("POST," September 2019 through February 2020) treated after pathway implementation to a historical cohort of hepatectomy patients ("PRE," March 2016 through December 2017) before our 2018 departmental opioid reduction efforts. Opioid volumes in the last 24 hours and prescribed at discharge were converted to oral morphine equivalents (OME) and compared between cohorts. RESULTS: There were 276 PRE and 100 POST patients. There was a similar proportion of major (PRE-34.1% vs POST-40%) and minimally invasive hepatectomies (PRE-19.9% vs POST-11%, p = 0.122). Implementation was associated with a shorter length of stay (median 5 d PRE vs 4 d POST, p < 0.001). Standardized opioid weaning was associated with a lower median last 24-hour OME (20 mg PRE vs 10 mg POST, p = 0.001). Using a standardized discharge calculation, median discharge OME were lower (200 mg PRE vs 50 mg POST, p < 0.001). More POST patients were discharged opioid-free (6.9% PRE vs 21% POST, p < 0.001). CONCLUSIONS: Implementation of post-hepatectomy care pathways was associated with a 50% reduction in last 24-hour OME, which, combined with a standardized discharge calculation, was associated with an overall 75% reduction in discharge opioid volumes and tripled opioid-free discharges. These data suggest that no-cost, reproducible pathways can be considered in abdominal operations with similar incisions/length of stay to decrease variation in opioid dosing while prioritizing patient-centric opioid needs.

Opioid Discharge Prescriptions After Inpatient Surgery: Risks of Rebound Refills by Length of Stay.

INTRODUCTION: As inpatient stays become shorter, one concern with standardizing discharge opioid prescriptions is the potential risk of "rebound refills." We sought to compare opioid prescription refill rates and volumes for surgical patients discharged on postoperative day (POD) 2-3, 4-7, and 8+. METHODS: In a prospective quality improvement protocol, faculty volunteered to use either a 5x-multiplier (5x) or usual care (UC) for discharge prescriptions after inpatient (≥48 h stay) surgery from Sep-Dec 2019. The 5x-multiplier is 5-times the patient's last 24-h opioid use (by oral morphine equivalents, OME). Cohorts were compared by POD of discharge: POD 2-3 ("SHORT"), POD 4-7 ("INTERMEDIATE"), and POD 8+ ("LONG"). The primary endpoint was 30-d refill rates. Secondary endpoints included 30-d refill OME and inpatient opioid weaning/discharge metrics. RESULTS: From 22 faculty, 409 patients were included. When stratified by POD, 154 (37.7%) were discharged SHORT, 176 (43.0%) INTERMEDIATE, and 79 (19.3%) LONG. SHORT stay patients had a median last 24-h OME of 10 mg (versus 5 mg INTERMEDIATE, 5 mg LONG; P = 0.268), and a median discharge OME of 55 mg (versus 75 mg INTERMEDIATE, 100 mg LONG; P = 0.221). Patients with SHORT stays did not have higher refill rates (11.7% versus 18.2% INTERMEDIATE, 19.0% LONG; P = 0.193) or higher median refill OME (150 mg versus 300 mg INTERMEDAITE, 339 mg LONG; P = 0.154). CONCLUSIONS: Despite concerns of increased refills, patients discharged by POD 2-3 were not associated with "rebound refills." A patient-centered 5x-multiplier standardization of discharge opioid prescriptions is feasible in all inpatient surgery patients, even those discharged following a short inpatient stay.

Impact of palliative therapies in metastatic esophageal cancer patients not receiving chemotherapy.

BACKGROUND: Palliative therapy has been associated with improved overall survival (OS) in several tumor types. Not all patients with metastatic esophageal cancer receive palliative chemotherapy, and the roles of other palliative therapies in these patients are limited. AIM: To investigate the impact of other palliative therapies in patients with metastatic esophageal cancer not receiving chemotherapy. METHODS: The National Cancer Database was used to identify patients between 2004-2015. Patients with M1 disease who declined chemotherapy and had known palliative therapy status [palliative therapies were defined as surgery, radiotherapy (RT), pain management, or any combination thereof] were included. Cases with unknown chemotherapy, RT, or nonprimary surgery status were excluded. Kaplan-Meier estimates of OS were calculated. Cox proportional hazards regression models were employed to examine factors influencing survival. RESULTS: Among 140234 esophageal cancer cases, we identified 1493 patients who did not receive chemotherapy and had complete data. Median age was 70 years, most (66.3%) had a Charlson Comorbidity Index (CCI) of 0, and 37.1% were treated at an academic center. The majority (72.7%) did not receive other palliative therapies. On both univariate and multivariable analyses, there was no difference in OS between those receiving other palliative therapy (median 2.83 mo, 95%CI: 2.53-3.12) vs no palliative therapy (2.37 no, 95%CI: 2.2-2.56; multivariable P = 0.290). On univariate, but not multivariable analysis, treatment at an academic center was predictive of improved OS [Hazard ratio (HR) 0.90, 95%CI: 0.80-1.00; P = 0.047]. On multivariable analysis, female sex (HR 0.81, 95%CI: 0.71-0.92) and non-black, other race compared to white race (HR 0.72, 95%CI: 0.56-0.93) were associated with reduced mortality, while South geographic region relative to West region (HR 1.23, 95%CI: 1.04-1.46) and CCI of 1 relative to CCI of 0 (HR 1.17, 95%CI: 1.03-1.32) were associated with increased mortality. Higher histologic grade and T-stage were also associated with worse OS (P < 0.05). CONCLUSION: Palliative therapies other than chemotherapy conferred a numerically higher, but not statistically significant difference in OS among patients with metastatic esophageal cancer not receiving chemotherapy. Quality of life metrics, inpatient status, and subgroup analyses are important for examining the role of palliative therapies other than chemotherapy in metastatic esophageal cancer and future studies are warranted.

Elevated DNA Oxidation and DNA Repair Enzyme Expression in Brain White Matter in Major Depressive Disorder.

Background: Pathology of white matter in brains of patients with major depressive disorder (MDD) is well-documented, but the cellular and molecular basis of this pathology are poorly understood. Methods: Levels of DNA oxidation and gene expression of DNA damage repair enzymes were measured in Brodmann area 10 (BA10) and/or amygdala (uncinate fasciculus) white matter tissue from brains of MDD (n=10) and psychiatrically normal control donors (n=13). DNA oxidation was also measured in BA10 white matter of schizophrenia donors (n=10) and in prefrontal cortical white matter from control rats (n=8) and rats with repeated stress-induced anhedonia (n=8). Results: DNA oxidation in BA10 white matter was robustly elevated in MDD as compared to control donors, with a smaller elevation occurring in schizophrenia donors. DNA oxidation levels in psychiatrically affected donors that died by suicide did not significantly differ from DNA oxidation levels in psychiatrically affected donors dying by other causes (non-suicide). Gene expression levels of two base excision repair enzymes, PARP1 and OGG1, were robustly elevated in oligodendrocytes laser captured from BA10 and amygdala white matter of MDD donors, with smaller but significant elevations of these gene expressions in astrocytes. In rats, repeated stress-induced anhedonia, as measured by a reduction in sucrose preference, was associated with increased DNA oxidation in white, but not gray, matter. Conclusions: Cellular residents of brain white matter demonstrate markers of oxidative damage in MDD. Medications that interfere with oxidative damage or pathways activated by oxidative damage have potential to improve treatment for MDD.