Surgery is the only treatment for biliary tract cancer (BTC) that have shown long term survival. BTCs are classified based on their anatomical site in the biliary tree [intrahepatic (IHCC), extrahepatic cholangiocarcinoma (EHCC)], and gallbladder cancer (GBC). Most patients are diagnosed in stage IV with distant metastases1 with a life expectancy of less than one year due to aggressive tumour biology and lack of effective systemic therapies.2

In cases with non-resectable BTC (locally advanced, recurrent, or metastatic), the current standard of care is systemic chemotherapy with gemcitabine and cisplatin. This regimen was established by the ABC-02 trial, the largest randomised phase III study to date, which showed a survival benefit of the combination of gemcitabine and cisplatin opposed to gemcitabine alone (11.7 vs. 9 months).2 Nevertheless, clinical response rates to these regimens are low, with <10% long term survival for all BTC subtypes and a complete response only in exceptional cases.2 Other chemotherapy combinations (5-Fluoruracile, capecitabine, oxaliplatin, and irinotecan) have only marginal improvements in survival.34

BTC has multiple potential mutations that could be used as a target for treatment, but there is a significant lack of evidence of such novel therapeutic strategies.5 Due to this, a greater appreciation of the molecular heterogeneity across the BTC subtypes must be paid, realising that these anatomically classified subgroups (IHCC, EHCC, or GBC) exhibit distinct molecular and potential therapeutic strategies (Fig. 1).6 Few cases of successful chemotherapy converting from initially metastatic BTC to resectable BTC have been reported478910 and none of them have combined biological therapy with long-term and disease-free survival. There is no current general consensus regarding this issue.

We present the case of a 44-year-old male suffering from diffuse abdominal pain who was diagnosed with GBC and with liver and distant lymph node metastases in November 2012 and referred to our centre tumour board. The work-up showed a CA 19-9 of 22,000 U/ml with no other abnormalities in the laboratory test. The CT, MRI, and PET-CT demonstrated a GBC with liver parenchymal infiltration and multiple liver metastases (Segments IVa-V-VIII) associated with suspected local and distant (interaortocaval) lymph nodes metastases. No vascular or bile duct invasion was detected (Fig. 2). An ultrasound biopsy of the liver metastases was performed which confirmed liver metastases from pancreatobiliary adenocarcinoma origin (CK7+, CK20−, P53+, K-RAS−, CDX2+, and BRAF−) (Fig. 3). From December 2012 to January 2013, three cycles of Gencitabine and Cisplastine-based therapy were started. In spite of this therapy, there was a worsening in the CA 19-9 levels (63.000 U/ml) and in the radiological findings. Her 2/Neu mutation was then studied, which showed an intense positive overexpression. Our multidisciplinary team decided to change the chemotherapy to Capecitabine plus Oxaliplatin and Trastuzumab for eight cycles. After six months, a complete radiological (Fig. 2) and metabolic response (PET-CT) (with normalisation in the CA 19-9 levels) was observed (Fig. 4). In November 2013, an exploratory laparotomy was carried out after four months of stable response without treatment. During the surgical procedure, no liver metastases were found on contrast-enhanced ultrasonography. Intraoperative interaortocaval lymph node and cystic duct frozen sections were negative for malignancy. Nevertheless, taking into account the extension of the initial disease, a mesohepatectomy associated with hiliar and interaortocaval lymphadenectomy was performed. The patient developed a Grade IIIa Dindo–Clavien morbidity (biliar fístula) which was managed with an ultrasound-guided puncture. He was discharged on postoperative day 22. Adjuvant therapy with Trastuzumab was administrated for four months. The histopathological exam demonstrated a moderately differentiated gallbladder adenocarcinoma pG2T2N0 (+0/15) M0 (no liver or lymph node metastases), and intense liver multifocal fibrosis. The cystic duct was negative for tumour. Today, the patient is now recurrence-free at five years.

The HER2/neu gene is located on the 17q12-q21 chromosomal region acting as an oncogene in several human cancers.11 The HER2 gene is a key driver in the development of several solid tumours, including breast, ovarian, and gastric cancer. Overexpression is observed in approximately 20 % of breast/ovarian cancers and 12% of gastric cancers.12 HER2 overexpression or amplification are predominantly seen in EHCC and GBCs (10–18%),13 and rarely in IHCC (1%).14 The prognostic role of HER2 overexpression or amplification is still controversial in BTC. Some studies failed to demonstrate the prognostic impact of HER2 overexpression, probably due to the relatively small sample size and heterogeneity of the patients studied,14 while other reports showed that it could be a bad prognosis factor.15

Trastuzumab is a monoclonal antibody that targets HER2. Javle et al.16 reported results from a retrospective study with Trastuzumab and concurrent chemotherapy in BTC. HER2 overexpression or amplification was present in eight out of nine GBC and three out of five EHCC. Moreover, the GBC group with HER2 overexpression or amplification experienced radiological stability in three out of eight cases, partial response in four out of eight, and a complete response in one out of eight. On the other hand, none of the EHCC had a radiological response, concluding that HER2/neu-directed therapy is a promising avenue for patients with GBC with gene amplification.16 Recently, with the preliminary data from the MyPathway trial, a prospective multicentric phase IIA study, it has been proposed that HER2/neu blockage with Pertuzumab plus Trastuzumab could be a promising treatment strategy for HER2-positive metastatic BTC. In this study, 11 patients with HER2-positive BTC were enrolled. With a median follow-up of 4.2 months, three patients had stability, and four had a partial response for more than four months.17 Currently, there is an ongoing Phase II clinical trial (ASLAN001), a pan-HER kinase inhibitor in refractory advanced or metastatic BTC (NCT02609958).

On the other hand, most of the data for neoadjuvant or conversion chemotherapy followed by surgery comes from small trials and case reports of BTC with advanced unresectable or metastatic disease.4789101819 None of these studies combined biological therapy with long-term and disease-free survival as the present case. Kato et al.18 revealed that the neoadjuvant Gemcitabine regimen is able to downsize tumours towards resectable stages in up to 36.4% with a comparable survival to those who were resectable at first (45% vs. 40.8% survival at five years). Even though the actual standard of care in unresectable BTC is Gemcitabine plus Cisplatin,2 a prospective trial comparing Gemcitabine plus Cisplatin versus Gemcitabine alone, failed to demonstrate any differences in resection and survival rates.19

Finally, there are no definitive radiological, metabolic, or biochemical criteria to define the adequate timing of possible salvage surgery after neoadjuvant or conversion chemotherapy for unresectable BTC. In our case, we performed a CT scan with CA 19-9 levels every four months during chemotherapy treatment and a PET-CT once there was a complete radiological and biochemical maintained response. Moreover, we think that the assessment of disease stability without treatment prior to surgery as a testtime during a defined period, but not inferior to four months, is crucial in order to re-check the biological aggressiveness of the tumour. Our patient was not initially treated as neoadjuvant but was treated in a palliative setting. Progression during first-line treatment prompted the change to study the Her 2/Neu mutation which showed an intense positive overexpression. Combination of HER2/neu-directed therapy (Trastuzumab) with secondline chemotherapy was able to achieve a long-term complete radiological, metabolic, and biochemical response. A curative intention surgery was performed and the patient is still alive recurrence-free after five years.

Conversion therapy in BTC has recently attracted attention, although there is insufficient evidence regarding the best chemotherapy treatment. To the best of our knowledge, the present case is the first report of a patient with a Stage IV GBC who achieved a five-year survival without recurrence after a conversion therapy combining chemotherapy plus Trastuzumab and radical salvage surgery. Trastuzumab therapy could be a promising treatment option in patients with HER2-positive advanced GBC, but further clinical trials are needed.