Clinical Study Oncology DOI: 10.1159/000509148

Received: May 26, 2020 Accepted: June 2, 2020 Published online: September 30, 2020

Outcomes of Advanced Gastroesophageal Cancer Patients with Equivocal HER2 Expression with or without ERBB2 Gene Amplification Ahmed Abdelhakeem a Xuemei Wang b Jane E. Rogers c Allison Trail a Meina Zhao a Mariela Blum-Murphy a J.S. Estrella d Jaffer A. Ajani a  

 

 

 

 

 

 

 

aDepartment

of Gastrointestinal Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; bDepartment of Biostatistics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; cPharmacy Clinical Programs, The University of Texas MD Anderson Cancer Center, Houston, TX, USA; dDepartment of Anatomical Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA

Abstract Background: Prior studies have shown that patients whose tumor overexpresses Her2 at 3+ level by immunohistochemistry (IHC) fare better than those whose tumor overexpresses Her2 at 2+ level (with ERBB2 amplified). Therefore, it would be important to compare the outcome of patients whose tumor expresses Her2 at 2+ level but further classify by gene amplification studies as positive or negative. Methods: We retrospectively identified patients with advanced gastroesophageal adenocarcinoma with low Her2 protein expression (2+ by IHC) whose tumors were evaluated for gene amplification of ERBB2 by fluorescence in situ hybridization (FISH). All patients received first-line therapy, and trastuzu­ mab was added according to Her2 status. We compared overall survival (OS), progression-free survival (PFS), and overall response rate (ORR) of the entire cohort and compared Her2-positive tumor patients’ outcomes with Her2negative tumor patients’ outcomes. All patients had treatment response assessments and follow-ups at our institution. Results: We identified 87 patients whose tumors

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expressed Her2 at 2+ level. 51 (58.6%) were Her2-negative and 36 (41.4%) were Her2-positive by FISH. For the entire cohort, the median OS was 26 months (95% confidence interval 16.6–37.6), and the median PFS was 12.2 months (95% confidence interval 9.7–19.3). Median OS, median PFS, and ORR did not differ between Her2-positive and Her2-negative patients (p = 0.70, p = 0.60, p = 0.91, respectively). Conclusions: Our data suggest that patients with Her2 positivity or negativity when tumors have lower Her2 protein expression (2 + by IHC) have similar clinical outcomes. Further research is warranted in this cohort. © 2020 S. Karger AG, Basel

Introduction

Gastric cancer represents the fifth most frequently diagnosed cancer and the third leading cause of cancer-related death, while esophageal cancer is ranked the seventh in terms of incidence and sixth in mortality overall [1]. Gastroesophageal adenocarcinomas (GEA) including those originating from distal esophageal, gastric, and gastroesophageal junction are associated with high mortality and a poor prognosis due to commonly being diagnosed Jaffer A. Ajani Department of Gastrointestinal Medical Oncology The University of Texas MD, Anderson Cancer Center 1515 Holcombe Blvd, Houston, TX 77030 (USA) jajani @ mdanderson.org

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Keywords HER2 · ERBB2 · FISH · Survival · Gastroesophageal cancer

Patients and Methods We conducted a retrospective evaluation of stage IV GEA patients treated at the University of Texas MD Anderson Cancer Center (MDACC), Houston, TX, USA. We reviewed our database for potential patients from October 2010 to March 2019. Patients were identified if they had untreated stage IV gastroesophageal cancer and tested 2+ for HER2 receptor protein by IHC and then either were negative or positive by FISH [6]. Patients were included if they received first-line treatment and were followed for response assessment at MDACC. Treatment included fluoropyrimidine/platinum-based therapy for FISH-negative patients. While those who were FISH positive received trastuzumab plus fluoropyrimidine/platinum-based therapy. No other selection criteria were implemented. Data collection included patient demographics (age, sex, and ethnicity), Eastern Cooperative Oncology Group (ECOG) performance status, baseline body mass index (BMI), primary site according to the Siewert-Stein anatomical classification for adenocarcinomas of the gastroesophageal area (gastric, gastroesophageal junction, or distal esophageal sites), histologic grade (well, moderate, or poorly differentiated), subtype by Lauren’s classification, and metastatic sites. Treatment and outcome data points col-

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Oncology DOI: 10.1159/000509148

Table 1. Demographic and clinical characteristics of patients

Median age (range), years Sex, n (%) Male Female Location of tumor, n (%) Esophagus Siewert type I Siewert type II Siewert type III Stomach Tumor differentiation, n (%) Well differentiated Moderately differentiated Poorly differentiated Adenocarcinoma subtype, n (%) Signet ring cell carcinoma Not signet ring cell carcinoma Tumor histology, n (%) Diffuse Intestinal Adenocarcinoma NOS Baseline T stage, n (%) T1 T2 T3 T4 Baseline N stage, n (%) N0 N1 N2 N3 NX Baseline M, n (%) M1 Baseline clinical stage, n (%) IV HER2 status by FISH, n (%) Positive Negative Response to first-line therapy, n (%) Complete response Partial response Stable disease Performance status (ECOG) 0 1 2 3

61 (27–87) 62 (71.3) 13 (4.9) 5 (5.7) 10 (11.5) 18 (20.7) 15 (17.2) 39 (44.8) 1 (1.2) 39 (44.8) 47 (54) 22 (25.3) 65 (74.7) 42 (48.3) 44 (50.6) 1 (1.1) 2 (2.3) 3 (3.4) 24 (27.6) 1 (1.1) 5 (5.7) 13 (14.9) 9 (10.3) 3 (3.4) 57 (65.5) 87 (100) 87 (100) 36 (41.4) 51 (58.6) 8 (9.2) 47 (54) 9 (10.3) 27 (31) 48 (55.2) 10 (11.5) 2 (2.3)

NOS, not otherwise specified; FISH, fluorescence in situ hybridization; ECOG, Eastern Cooperative Oncology Group.

lected were overall survival (OS), progression-free survival (PFS), and overall response rate (ORR). The OS was defined as the time interval between the date of first treatment and the date of death and was censored at the last follow-

Abdelhakeem/Wang/Rogers/Trail/Zhao/ Blum-Murphy/Estrella/Ajani

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at an advanced stage. The overall 5-year survival rate for all comers is estimated to be 15–25% [2]. Prognostic molecular biomarkers have been studied to identify novel therapeutic targets for advanced GEA treatment. Human epidermal growth factor receptor 2 (HER2) overexpression in GEA is reported in approximately 10–30% of all cases with variation in incidence based on tumor location, tumor subtype (diffuse type vs. intestinal type), and histology grade [3]. Overexpression of the HER2 receptor protein might be associated with an aggressive growth pattern and higher frequencies of recurrence of gastroesophageal cancers [3, 4]; however, there are contradictory results [5]. HER2 protein and gene expression in GEA is evaluated with immunohistochemistry (IHC) scoring and/or fluorescence in situ hybridization (FISH) in order to make a clinical decision [5]. HER2 overexpression is defined as positive when HER2 score is 3+ by IHC or HER2 score is 2+ by IHC but must be associated with HER2 gene amplification by FISH [5]. Currently, trastuzumab is recommended to be added to the front-line chemotherapy that consists of platinum (oxaliplatin or cisplatin) plus fluoropyrimidine (5-fluorouracil (5-FU) or capecitabine) for HER2-positive advanced GEA patients [6]. Patients who have a tumor that is negative for HER2 are given platinum plus fluoropyrimidine as front-line therapy. We evaluated our IHC equivocal Her2 patients to review the trastuzumab benefit in the Her2-positive tumor patients compared to the Her2-negative tumor patients.

0.8

0.8

0.4 0.2 0

0.6 0.4 0.2

p-value = 0.70

0 0

20

40

60

80

Time from first line treatment, months

100

Fig. 1. Kaplan-Meier estimate of overall survival from date of first treatment in the total patient population. Dotted lines indicate confidence boundaries.

up date for patients who were alive. PFS was defined as the time interval between the first-line treatment start date and the first progression date or death date, whichever occurred first, and was censored at the last follow-up date for patients who were alive without progression. Statistical Analysis The Kaplan-Meier method was used to estimate the probabilities of OS and PFS. Cox proportional hazards regression models were applied to assess the association between patient characteristics and time-to-event outcomes. The statistical analyses were performed using SAS 9.4 [The SAS Institute, Cary, NC, USA] and Splus 8.2 [TIBCO, Palo Alto, CA, USA].

0

20

40

60

80

Time from first line treatment, months

100

Fig. 2. Kaplan-Meier estimate of overall survival stratified by FISH

status.

Table 2. Summary of response by FISH status

FISH negative FISH positive

SD/PD/Resistant

CR/PR

19 (37%) 13 (36%)

32 (63%) 23 (64%)

SD, Stable disease; PD, progressive disease; CR, complete response; PR, partial response; FISH, fluorescence in situ hybridization.

A total of 87 patients were included. 51 (58.6%) patients were tested negative by FISH (meaning Her2 negative) and the remaining 36 (41.4%) patients were positive by FISH (meaning Her2 positive). Demographic and clinical characteristics are summarized in Table 1. 42 (48.3%) patients had a diffuse-type adenocarcinoma, 44 (50.6%) patients had an intestinal-type adenocarcinoma, and only one patient had a non-specified adenocarcinoma. The median follow-up time among survivors was 37 months (95% CI: 25–56.2). Among the total 87 patients, 48 (55%) patients died and 39 (45%) were alive at the last follow-up (Fig. 1). The ORR for of the entire cohort was 63% (n = 55); among the Her2-negative patients, the response rate was 63%, and the Her2-positive tumor patients had a response rate of 64% (p = 0.91; χ2 test; Table 2).

Among the 87 patients who received first-line treatment, 61 (70%) patients had cancer progression or died, and 26 (30%) patients were alive without progression at the last follow-up. The median OS for the entire group was 26 months (95% CI: 16.6–37.6). The 1-year survival rate was 79% (95% CI: 71–89), and the 3-year survival rate was 37% (95% CI: 26–52; Fig. 1). OS according to Her2 status was not significantly different in the two groups (p = 0.70; Fig. 2; Table 3). The median OS for the Her2negative group was 25.4 months (95% CI: 14.7– not estimable), while the median OS for the Her2-positive group was 26.8 months (95% CI: 15.5–46.3; Table 4). The median PFS for the entire cohort was 12.2 months (95% CI: 9.7–19.3). The 1-year PFS was 51% (95% CI: 41–63). The 3-year PFS was 19% (95% CI: 12–33). PFS according to the Her2 status was similar in the two groups (p = 0.60; Table 5). The median PFS for the FISH-negative group was 12.8 months (95% CI: 10.6–26.7), while the median PFS for the FISH-positive group was 11.2 months (95% CI: 7.4–21.7; Table 4).

Outcomes in Equivocal HER2 Gastroesophageal Cancer

Oncology DOI: 10.1159/000509148

Results

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0.6

FISH = negative (25/51) FISH = positive (23/36)

Color version available online

1.0 Overall survival probability

Overall survival probability

1.0

Table 3. Univariate Cox regression model of OS (48 deaths in 87 patients)

Performance status (ECOG) 1 versus 0 2, 3 versus 0 Location of tumor Siewert 3/Gastric vs. Siewert 1/ Siewert 2/Esophagus Baseline T T3 versus T1/T2 T4 versus T1/T2 TX versus T1/T2 Baseline N N1 versus N0 N2 versus N0 N3 versus N0 NX versus N0 Tumor differentiation Poorly differentiated vs. Well/ Moderately differentiated HER2 status by FISH Positive versus Negative

HR (95% CI)

p value

Feature

FISH negative (n = 51)

FISH positive (n = 36)

1.13 (0.61, 2.10) 2.06 (0.75, 5.70)

0.70 0.16

1.55 (0.86, 2.80)

0.15

1.40 (0.31, 6.25) 9.05 (0.78, 105.14) 2.15 (0.51, 9.04)

0.66 0.08 0.30

0.42 (0.11, 1.70) 0.39 (0.09, 1.78) 0.83 (0.13, 5.15) 0.78 (0.23, 2.61)

0.22 0.22 0.84 0.69

Median OS, months 95% CI One-year OS, % 95% CI Three-years OS, % 95% CI Median PFS, months 95% CI One-year PFS, % 95% CI Three-years PFS, % 95% CI

25.4 14.7– not estimable 82 72–94 35 21–58 12.8 10.6–26.7 55 42–73 20 10–42

26.8 15.5–46.3 76 62–92 38 24–61 11.2 7.4–21.7 46 32–66 18 9–38

1.37 (0.77, 2.43)

0.28

0.89 (0.50, 1.58)

0.70

ECOG, Eastern Cooperative Oncology Group; HR, hazard rate; CI, confidence interval; FISH, fluorescence in situ hybridization. Table 5. Univariate Cox regression model of PFS (61 progression/

deaths in 87 patients)

Clinical feature

HR (95% CI)

Performance status (ECOG) 1 versus 0 1.09 (0.63, 1.89) 2, 3 versus 0 1.76 (0.70, 4.43) Location of tumor Siewert 3/Gastric vs. Siewert 1/ 1.40 (0.82, 2.40) Siewert 2/Esophagus Baseline T T3 versus T1/T2 2.13 (0.48, 9.42) T4 versus T1/T2 11.96 (1.04, 138.16) TX versus T1/T2 3.83 (0.91, 16.05) Baseline N N1 versus N0 0.69 (0.18, 2.64) N2 versus N0 1.07 (0.28, 4.17) N3 versus N0 1.17 (0.19, 7.19) NX versus N0 1.51 (0.46, 4.93) Tumor differentiation Poorly differentiated vs. Well/ 1.62 (0.97, 2.72) Moderately differentiated HER2 status by FISH Positive versus Negative 1.14 (0.69, 1.89)

p value 0.76 0.23 0.22 0.32 0.05 0.07 0.58 0.92 0.86 0.50

Oncology DOI: 10.1159/000509148

FISH, fluorescence in situ hybridization; OS, overall survival; CI, confidence interval; PFS, progression-free survival.

Discussion

Her2 biology in GEA is complicated by its heterogeneous and sometimes sparse expression; however, several studies have pointed to an advantage when tumor cells have high levels of Her2 protein expression (3+ by IHC) compared to 2+ [3, 7–9]. It is not clear if the patients’ outcome is different if Her2 expression is at a lower level (e.g., 2+ by IHC) in the presence or absence of gene amplification. Therefore, we retrospectively studied this select population. Our data show that there is no difference between the Her2positive tumor patients and Her2-negative tumor patients when Her2 is expressed at 2+. All Her2-positive tumor patients received trastuzumab and the Her2-negative patients did not. The outcome of our entire cohort of 87 patients is excellent, but we found no difference in the outcome (OS, PFS, and ORR) based on the Her2 status. Our study is limited in its scope for several reasons: (1) a single-center experience, (2) retrospective in nature, and (3) the total number of patients is limited. Nevertheless, our findings are unexpected showing no effect of trastuzumab on patients’ outcomes. We believe further studies are warranted especially with novel Her2-targeting agents such as bispecific antibodies or antibody-drug conjugates.

0.07 0.60

ECOG, Eastern Cooperative Oncology Group; HR, hazard rate; CI, confidence interval; FISH, fluorescence in situ hybridization.

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status

Acknowledgment Our research is supported by the NIH/NCI under award number P30CA016672 and used the Clinical Trials Office and the Biostatistics Resource Group.

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Clinical feature

Table 4. Kaplan-Meier estimates for OS and PFS, grouped by FISH

Statement of Ethics

Funding Sources

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation and with the Helsinki Declaration of 1964 and later versions. Our study was approved by the University of Texas MD Anderson Cancer Center’s Institutional Review Board (IRB) for protocol PA12-1063, where written informed consent or a substitute for it was obtained from all patients included in the study.

Conflict of Interest Statement

The authors received no specific funding for this work.

Author Contributions Ahmed Abdelhakeem: data collection, analysis, and writing. Xuemei Wang: data analysis and writing. Jane E. Rogers: writing. Allison Trail: writing. Meina Zhao: writing. Mariela Blum-Murphy: writing and patients. J.S. Estrella: writing. Jaffer A. Ajani: administrative, patients, interpretation, and writing.

There is no relevant conflict of interest to be declared by any author.

References

Outcomes in Equivocal HER2 Gastroesophageal Cancer

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Oncology DOI: 10.1159/000509148

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