Trastuzumab and pertuzumab in circulating tumor dna erbb2-amplified her2-positive refractory cholangiocarcinoma

ABSTRACT Cholangiocarcinoma is a heterogeneous and target-rich disease with differences in actionable targets. Intrahepatic and extrahepatic types of cholangiocarcinoma differ significantly

in clinical presentation and underlying genetic aberrations. Research has shown that extrahepatic cholangiocarcinoma is more likely to be associated with _ERBB2_ (HER2) genetic aberrations.

Various anti-HER2 clinical trials, case reports and other molecular studies show that HER2 is a real target in cholangiocarcinoma; however, anti-HER2 agents are still not approved for

routine administration. Here, we show in a metastatic cholangiocarcinoma with _ERBB2_ amplification identified on liquid biopsy (circulating tumor DNA (ctDNA) testing), a dramatic response

to now over 12 months of dual-anti-HER2 therapy. We also summarize the current literature on anti-HER2 therapy for cholangiocarcinoma. This would likely become another treatment option for

this target-rich disease. SIMILAR CONTENT BEING VIEWED BY OTHERS ANTITUMOUR ACTIVITY OF NERATINIB IN PATIENTS WITH _HER2_-MUTANT ADVANCED BILIARY TRACT CANCERS Article Open access 06

February 2023 SECOND-LINE THERAPY IN PANCREATIC DUCTAL ADENOCARCINOMA (PDAC) PATIENTS WITH GERMLINE BRCA1-2 PATHOGENIC VARIANTS (GBRCA1-2PV) Article 08 December 2022 CIRCULATING TUMOR

DNA-GUIDED TREATMENT WITH PERTUZUMAB PLUS TRASTUZUMAB FOR _HER2_-AMPLIFIED METASTATIC COLORECTAL CANCER: A PHASE 2 TRIAL Article Open access 11 November 2021 INTRODUCTION Cholangiocarcinoma

(CCA) is a lethal tumor arising from the epithelium of the bile ducts that most often presents at an advanced stage. A total of 10–20% of primary hepatic malignancies are CCA, which is the

second most common hepatobiliary malignancy.1 Risk factors for development of CCA include cigarette smoking, heavy alcohol use, primary sclerosing cholangitis, viral hepatitis B and C, and

genetic diseases such as Lynch syndrome.2 CCA, including gallbladder cancer, is a heterogeneous group of diseases. Multiple aberrations can be seen, including _ERBB2_, microsatellite

instability high (MSI-H), _IDH1_, _BRAF_, _FGFR_ fusion, _BRCA_/DNA-repair related, _MET_ amplification, _NTRK_ fusion, _TP53_, _KRAS_, _ARID1A_, _MCL1_, _PBRM1_, _SMAD4_, _FBXW7_, and

_CDKN2A_.3,4,5,6,7,8,9,10 As in most cancers, these aberrations are not actionable; however, cholangiocarcinoma is a very “target rich” disease; _ERBB2_, _MSI-H_, _IDH1_, _BRAF_, _FGFR

fusion_, _MET amplification_, and _NTRK_ fusion5,6,8,9,11 may be susceptible to approved or off-label or presence of drugs treatments through clinical trials that are showing promise.

Tumor-agnostic FDA-approved immunotherapy for MSI-H tumors and larotrectinib for NTRK-fusion tumors are showing promise.9,12 A number of published cases and open clinical trials with early

results have demonstrated activity in _IDH1_, _BRAF_-mutant, _MET_-amplified, _ERBB2_-amplified, and _FGFR-_ fusion tumors.6,7,13,14 The _ERBB2_ gene encodes for the protein HER2 or

HER2/neu, which is a tyrosine kinase family receptor. Breast, stomach and esophageal cancers have well-established associations with _ERBB2_ genetic aberrations; and are approved for

anti-HER2.15,16 However, reports have also shown the finding of HER2 aberrations in CCA and urinary bladder cancers.17 These are interestingly seen more with extrahepatic cholangiocarcinomas

and gallbladder cancers as opposed to intrahepatic cholangiocarcinomas. We present a 71-year-old female diagnosed with metastatic CCA with _ERBB2_ (HER2) 3+ amplification determined by

circulating tumor DNA (ctDNA) testing (“liquid biopsy”) and confirmed by tissue-based testing. She was treated with dual HER2-directed therapy (trastuzumab/pertuzumab), and responded very

well with regression of tumor on imaging as well as normalization of liver function tests and tumor marker levels including improvement in her overall clinical status. Serial ctDNA testing

(Table 1) alongside standard of care imaging continues to show ongoing durable control >12 months into therapy. Other case reports and studies highlighting the association of HER2 and CCA

are also presented. The patient provided written informed consent to report this case. RESULTS CASE PRESENTATION A 71-year-old female presented in December 2017 after diagnosis of

metastatic CCA. Ultrasound demonstrated innumerable liver lesions, which on confirmed on follow-up computed tomography and magnetic resonance imaging showing multiple liver lesions

consistent with CCA with intrahepatic metastases. The patient was also noted to have metastatic periportal and aortocaval adenopathy. The patient was not a candidate for surgical

intervention due to bilobar disease with innumerable liver lesions. Platinum-based chemotherapy was recommended. She was started on a combination carboplatin and gemcitabine (not cisplatin

due to age and sensorineural hearing loss). A baseline ctDNA test was obtained as part of the standard of care at our institution for patients with gastrointestinal malignancies, and in

particular cholangiocarcinoma, given the target-rich nature of the disease. Testing is performed through commercially available platforms. Guardant360 testing showed _ERBB2_ (HER2)

amplification 3+ and was confirmed through tumor tissue-based immunohistochemistry as well as genetic testing through the commercially available platform by Tempus confirming this (Fig. 1).

Given the liver-predominant nature of the disease, upfront Y90-radioembolization was also planned. However, within 2 months, the patient had rapid progression of disease with rising tumor

markers, rising ctDNA levels, derangement in liver function tests and decline in clinical condition. We initially considered the patient’s eligibility for the MyPathway Study which has an

arm for dual-anti-HER2 therapy.18 However, due to her rapid decline was deemed ineligible. Best supportive/palliative care vs. off-label anti-HER2 therapy was discussed. Given the patient’s

excellent overall baseline performance status, we began off-label treatment with anti-HER2 pertuzumab/trastuzumab combination therapy. Immediate and rapid improvement of tumor markers was

noted. After just one treatment, the patient’s liver function tests improved; most notably, the dominant _TP53_ mutation reduced from 60.7 to 2.1% (Table 1). Clinical variables continued to

improve rapidly through and continues to do so now over a year into treatment. Scans also showed excellent ongoing durable response (Fig. 2a, b). DISCUSSION CCA is classified into

intrahepatic and extrahepatic types based on anatomic location. These are clinically different from each other in terms of presentation, and more importantly the type and frequency of

genetic aberrations. Generally, intrahepatic CCA is associated with _IDH1_, _FGFR_ fusion and _BRCA_/DNA-repair gene alterations, while extrahepatic CCA is more frequently associated with

_ERBB2_ genetic aberrations.19 A number of these aberrations are potentially actionable in terms of FDA-approved therapies and/or availability of clinical trials or off-label therapies. For

a rare disease like CAA, even the latter are pertinent. There are several well-established risk factors related to the development of CCA. However, it has been reported that only 10% of

intrahepatic CCA is associated with these risk factors and the remaining 90% are sporadic.20 What is unique about our case is that the HER2 aberration was detected on circulating tumor DNA

testing (“liquid biopsy”). This was later confirmed on tissue-based testing (Fig. 1). This would not have been known otherwise. Furthermore, for a patient with refractory cholangiocarcinoma

that progresses on frontline therapy, prognosis in such situations is in the order of weeks–months. The fact that patient continues to have durable control 12 months and beyond is very

encouraging and unprecedented. Progression-free survival of second-line chemotherapeutic regimens is in the order of 4 months on average. Several studies have described the association of

CCA subgroups with various aberrations (Table 2). Churi et al. examined 75 CCA patients for tumoral genetic differences. They identified _TP53_, _KRAS_, _ARID1A_, _IDH1_, _MCL1_, and _PBRM1_

mutations in 35%, 24%, 20%, 18%, 16%, and 11% of intrahepatic CCA patients, respectively. _TP53_, _KRAS_, _ERBB2_, _SMAD4_, _FBXW7_, and CDKN2A were found in 45%, 40%, 25%, 25%, 15%, and

15% of extrahepatic CCA patients, respectively.19 The finding of a higher proportion of _ERBB2_ mutations in extrahepatic CCA and gallbladder cancer suggests that these patients are more

likely to carry it as opposed to intrahepatic CCA. Yoshikawa et al. measured HER2/neu expression in 236 cases of CCA by immunohistochemistry. They reported a 0.9% and 8.5% positive HER2/neu

expression rate in intrahepatic and extrahepatic CCAs, respectively.21 In a study by Lee et al., HER2 and HER3 overexpression was observed in 6% and 39%, respectively, in patients with

extrahepatic CCA, with HER3 overexpression associated with worse survival.22 A systemic review and meta-analysis by Galdy et al. showed a stronger rate of HER2 expression in extrahepatic CCA

(~20%) vs. intrahepatic CCA (<5%).23 Summary of the studies showing _HER2_ aberrations in CCA and treatment outcomes where available are presented in Table 2. In terms of this particular

assay’s ability to detect _ERBB2_ (HER2/neu) amplification, data were presented by the group from M.D. Anderson Cancer Center at the American Society of Clinical Oncology Conference (ASCO)

2018.24,25 Bardelli and colleagues validated the performance of the Guardant360 ctDNA assay retrospectively in a cohort of HER2/neu amplified metastatic colorectal cancer patients treated in

the landmark HERACLES study (phase 2 study of lapatinib plus trastuzumab). The group investigated 48 plasma samples from 29 patients. CtDNA was identified in 47–48 samples; ERBB2

amplification was confirmed in 46 of these 47 (97.9%) samples. The authors reported that a threshold of ≥3 copies of ERBB2 in circulation allowed identification of 94% of fluorescence in

situ hybridisation-positive patients. This threshold also correlated with clinical response.24,25 These results have been validated in other tumor types and cohorts of patients.25,26 Liquid

biopsy, therefore, appears to be a reliable and valid tool to detect ERBB2 (Her2/neu), which is indeed an actionable finding across many tumor types including cholangiocarcinoma. HER2/neu

blockade has shown favorable results in cancers carrying HER2 aberrations. Javle et al. investigated the response of anti-HER2 therapy in 8 patients with HER2 mutated gallbladder cancer and

showed an overall improvement in terms of disease stability (_n_ = 3), partial response (_n_ = 4), or complete response (_n_ = 1) in their entire patient cohort.27 In another study, the

researchers studied HER2/neu expression in extrahepatic CCA patients (_n_ = 84) and reported that anticancer therapy targeting HER2 receptors may be a reasonable option for these patients.28

Our patient has responded very well to anti-HER2 drugs and showed an improvement in symptoms, lab results and shrinkage in tumor size. This implicates the use of targeted therapy as a

favorable option in CCA alongside other patients who received anti-HER2-based therapy (Table 2). CCA diagnosis at an advanced stage has very poor outcomes and is often considered incurable.

Valle et al.29 reported a study of metastatic CCA patients (_n_ = 410), and reported median overall survival of 11.7 months and 8.1 months in a cisplatin–gemcitabine group and gemcitabine

group, respectively. In the second-line setting, outcomes are extremely poor (progression-free survival, 3–4 months; overall survival, 6 months). Compared to historical reports, outcomes in

patients receiving anti-HER2 therapy in HER2/neu+ CCA is by far superior and very encouraging (Table 2).30,31 Our patient at one point was given a choice of hospice and was not eligible for

any of the trials due to deranged liver function tests. But now on off-label dual-anti-HER2 therapy continues to be on treatment with excellent performance status without any chemotherapy

for more than 12 months at present. For rare, target-rich diseases like CCA, there is a need to consider approval and it is encouraging to see some recent tumor-agnostic approvals, such as

immunotherapy for MSI-H and larotrectinib for NTRK-fusion cancers.9,12 We believe our case and recent single-arm phase 2 study outcomes warrant consideration toward approval of anti-HER2

agents (trastuzumab/pertuzumab) in patients with CCA with _ERBB2_ amplification who have very limited options and poor prognosis. Furthermore, liquid biopsy testing for HER2 is not routinely

performed at most institutions. Our patient’s positive finding would have been missed. In target-rich diseases such as CCA, where tissue acquisition is a challenge, liquid biopsy provides a

viable alternative for both diagnostic and monitoring techniques. In conclusion, we were able to identify _ERBB2_ (HER2/neu_)_ amplification on liquid biopsy in a patient with CCA and found

anti-HER2 therapy as an effective treatment strategy. This will have implications for other patients with CCA in terms of identification of this target and considerations toward anti-HER2

therapy on- or off-trial. METHODS The patient provided written informed consent for her case to be presented. Separate IRB/FDA approval not required for off-label use of the anti-HER2

therapy or reporting of the case. REPORTING SUMMARY Further information on research design is available in the Nature Research Reporting Summary linked to this article. DATA AVAILABILITY The

authors declare that data supporting the findings of this study are available within the paper. Commercially available platforms were employed with results shown in the figures and tables

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_HPB_ 13, 309–319 (2011). Article  Google Scholar  Download references AUTHOR INFORMATION AUTHORS AND AFFILIATIONS * Division of Oncology, CORPS Program, Department of Internal Medicine,

Mayo Clinic, Jacksonville, FL, USA Bhavya Yarlagadda, Vaishnavi Kamatham, Ashton Ritter & Faisal Shahjehan * Division of Hematology, Oncology and Blood & Bone Marrow Transplantation,

Department of Internal Medicine, University of Iowa, Iowa City, IA, USA Pashtoon M. Kasi Authors * Bhavya Yarlagadda View author publications You can also search for this author inPubMed 

Google Scholar * Vaishnavi Kamatham View author publications You can also search for this author inPubMed Google Scholar * Ashton Ritter View author publications You can also search for this

author inPubMed Google Scholar * Faisal Shahjehan View author publications You can also search for this author inPubMed Google Scholar * Pashtoon M. Kasi View author publications You can

also search for this author inPubMed Google Scholar CONTRIBUTIONS P.M.K. conceived the idea, and is the patient’s primary oncologist alongside A.R. B.Y. drafted the initial draft alongside

comprehensive literature review by F.S. and S.K. Additional details provided by A.R. P.M.K. revised the draft before an additional round of revisions by all authors. This was approved by all

authors before submission to the journal. P.M.K., S.K., and A.R. revised the paper. All authors again approved of the final changes before resubmission. CORRESPONDING AUTHOR Correspondence

to Pashtoon M. Kasi. ETHICS DECLARATIONS COMPETING INTERESTS The authors declare no competing interests. ADDITIONAL INFORMATION PUBLISHER’S NOTE: Springer Nature remains neutral with regard

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license, visit http://creativecommons.org/licenses/by/4.0/. Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Yarlagadda, B., Kamatham, V., Ritter, A. _et al._ Trastuzumab and

pertuzumab in circulating tumor DNA ERBB2-amplified HER2-positive refractory cholangiocarcinoma. _npj Precis. Onc._ 3, 19 (2019). https://doi.org/10.1038/s41698-019-0091-4 Download citation

* Received: 22 March 2019 * Accepted: 26 July 2019 * Published: 19 August 2019 * DOI: https://doi.org/10.1038/s41698-019-0091-4 SHARE THIS ARTICLE Anyone you share the following link with

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