Cancers of the gastrointestinal (GI) tract (esophagus, stomach, small and large intestines, and anus) account for nearly 12% of all cases of cancer in the United States and 20% of cancer deaths. Colon cancer is by far the most common of these malignancies, with cancer of the rectum, stomach, esophagus, small intestine, and anus occurring with decreasing frequency. Surgery continues to be the principal curative modality, but radiation and chemotherapy have increasingly important roles and, in certain adjuvant settings, improve the cure rate produced by surgery. Select patients with isolated, resectable metastatic colorectal cancer lesions also may be cured with surgical resection. Chemotherapy alone is not curative in patients with overt metastatic disease. Recent combination drug regimens have produced objective responses in up to 60% of patients, with increasing numbers of individuals obtaining stabilization of their disease. There is little question that meaningful palliation and an increase in survival can be achieved in patients who respond to chemotherapy or achieve disease stabilization. Clinical trials, often by cooperative groups, have been useful in defining the natural history and therapeutic benefit of various treatment modalities. Participation in such clinical trials is encouraged because not only could participation provide benefit for the patient but also could reveal future therapeutic options for others. Staging of all GI neoplasms using the American Joint Committee on Cancer Staging Manual is essential to determine appropriate treatment for all tumor sites.¹

In the United States, an estimated 16,980 new cases and 15,590 deaths due to esophageal cancer were expected in 2014.² Incidence rates vary internationally with the highest rates seen in Southern and Eastern Africa and Eastern Asia. The lowest rates are found in Western and Middle Africa and Central America in both males and females.³ Esophageal cancers are either esophageal adenocarcinoma (EAC) or esophageal squamous cell carcinoma (ESCC). Historically, ESCC has predominated. In the 1960s, ESCC accounted for more than 90% of all esophageal tumors in the United States,
and adenocarcinomas were considered uncommon. For the past two decades, however, the incidence of EAC has increased dramatically in Western countries, and EAC now accounts for more than 60% of all esophageal cancers in the United States. In contrast, worldwide, ESCC still predominates.⁴

ESCC and EAC differ in a number of features, including tumor location and risk factors. EAC tends to involve the lower third of the esophagus, whereas the middle third is the most common site for ESCC. Smoking and regular alcohol use are strong risk factors for ESCC and only moderate risk factors for EAC. A unique risk factor for ESCC is other aerodigestive tract malignancies, such as head and neck or lung cancer. Risk factors associated with EAC appear to be gastroesophageal reflux disease (GERD), smoking, obesity, and Barrett esophagitis.⁵

Because ESCC and EAC appear to have distinct pathogenesis, epidemiology, biology, and outcomes, the most recent 2010 tumor-node-metastasis (TNM) staging system provides separate stage groupings.⁶ This change was based on an analysis of worldwide data on 4,627 patients with esophageal or gastroesophageal junction (GEJ) cancer who underwent surgery alone, and this showed that among patients with lymph node-negative tumors, prognosis was dependent on T-stage as well as histology, grade, and tumor location.⁷

Carcinoma of the esophagus is usually associated with progressive and persistent dysphagia. Pain, hoarseness, weight loss, and chronic cough are unfavorable manifestations that indicate spread to regional structures (e.g., mediastinal nodes), recurrent laryngeal nerves, or fistula formation between the esophagus and the airway. The most common sites of metastasis are regional lymph nodes (which may include cervical, supraclavicular, intrathoracic, diaphragmatic, celiac axis, or periaortic lymph nodes), the liver, and lungs.

Diagnosis is usually made by barium swallow or endoscopy with a biopsy or lavage cytology. Staging should be assessed with a computed tomography (CT) scan of the abdomen and chest, careful physical examination of the cervical and supraclavicular nodes, and positron emission tomography (PET). PET/CT appears to be most sensitive for identifying occult metastatic disease and less effective at accurately identifying regional nodal metastases. In patients without metastatic disease identified, endoscopic esophageal ultrasound (EUS)⁸ may be useful in assessing the depth of tumor invasion, given the difference in management of T1 to T2 lesions versus T3 to T4 lesions and regional nodal metastases. Laparoscopy to detect occult intraperitoneal metastases in distant esophageal and esophagogastric junction (EGJ) tumors has the advantage of changing management in approximately 17% of patients
who have otherwise been fully staged with CT, PET/CT, and EUS.⁹ Bronchoscopy should be considered for upper- and middle-third tumors to rule out a bronchoesophageal fistula. A bone scan is useful in patients with bone pain or tenderness. Survival is related to pathologic stage, which can be defined only surgically.

The management of locoregional esophageal cancer has undergone significant changes over the last 15 years and the majority of these patients are now treated with combined-modality therapy rather than local therapy alone. However, the optimal management of these patients remains unclear. Complete surgical resection results in a median survival of approximately 18 months with 15% to 20% of patients surviving 5 years. Patients with metastatic disease are best treated with systemic therapy. Palliative feeding procedures such as with a jejunostomy or gastrostomy tube may be useful if subsequent surgical resection is not to be done. For metastatic disease, the overall median survival time is less than 1 year, and the overall 5-year survival rate is 5% to 10%. The prognosis is related to the size of the lesion, the depth of penetration of the esophagus, and nodal involvement.

Only approximately 30% to 40% of patients diagnosed with esophageal cancer have potentially resectable disease at presentation; however, surgery has historically been included in standard treatment approaches. The utility of surgery alone, however, has been challenged owing to the poor prognosis with 5-year survival rates 15% to 20% with surgery alone.¹⁰,¹¹,¹²,¹³,¹⁴ In an analysis of 4,627 patients with esophageal cancer treated with surgery alone, those with T1N0 disease had 5-year survivals more than 50%, and therefore, surgery alone is still the standard care with those with T1N0 disease.¹⁵

The poor results with immediate surgery, due in part to inadequate staging techniques, have focused attention for some years on preoperative combined-modality treatment with radiation therapy, chemotherapy, or both, followed by surgery. When this approach is used, aggressive staging including EUS, CT scanning, PET/CT, and laparoscopy is needed and is often combined with jejunostomy feeding tube placement for nutritional support. Despite conflicting results from randomized trials, patients with stages II and III disease are often treated in this fashion.

The National Cancer Institute (NCI) Gastrointestinal Intergroup has reported a randomized trial of 440 patients with either EAC or ESCC that compared preoperative chemotherapy (cisplatin and fluorouracil [CF] for three cycles) versus surgery alone. After a median follow-up of 55.4 months,
there were no median, 1-year, or 2-year survival differences between the two groups. These results differ compared with data from the Medical Research Council Clinical Trials Unit in the United Kingdom, which included 802 patients randomized to receive either two cycles of preoperative CF followed by surgery or surgery alone. Approximately 66% of patients had adenocarcinoma. Long-term follow-up at 6 years revealed a significant difference in 5-year overall survival (OS) (chemotherapy vs. surgery alone, 23% vs. 17.1%; hazard ratio [HR], 0.84; 95% confidence interval [CI], 0.72 to 0.98; p = 0.03) regardless of histologic subtype.¹⁶ Different proportions of the two different histologies contribute to the difficulties in interpretation of these trials.

Radiation therapy alone, as either a preoperative or a postoperative adjunct to surgery, has not improved OS in most series, with 5-year survival rates ranging from 0% to 10%. Combined-modality treatment of radiotherapy with chemotherapy has been superior. In addition, concurrent chemotherapy and radiotherapy is superior to sequentially administered treatment.¹¹,¹⁷,¹⁸ In a randomized trial, Radiation Therapy Oncology Group (RTOG) 85-01, comparing radiotherapy alone with radiotherapy plus chemotherapy in 121 patients, 88% of whom had squamous cell cancer, the RTOG reported a 5-year survival rate of 27% for the combined-modality group and 0% for the radiation therapy alone group, with median survival times of 14.1 and 9.3 months, respectively. Most patients had stage T2 disease and were node-negative by CT scanning.¹⁹ There have been five completed trials that compared preoperative concurrent chemoradiation versus surgery alone, with two showing statistically significant survival benefits of chemoradiation.²⁰ The first trial, CALGB 9781, closed prematurely because of poor accrual and randomized only 56 patients to either esophagectomy with node dissection alone or cisplatin 100 mg/m² and fluorouracil 1,000 mg/m²/day for 4 days on weeks 1 and 5 concurrent with radiation therapy followed by esophagectomy with node dissection. An intent-to-treat analysis showed a median survival of 4.48 versus 1.79 years in favor of trimodality therapy (exact stratified log-rank, p = 0.002).²¹ The CROSS trial randomly assigned 363 patients with potentially resectable esophageal or EGJ cancer to preoperative chemoradiation using weekly paclitaxel 50 mg/m² plus carboplatin area under the curve (AUC) 2 plus concurrent radiotherapy (41.4 Gy over 5 weeks) versus surgery alone.²² The complete (R0) resection rate was higher with chemoradiotherapy (92% vs. 69%), and 29% of those treated with chemoradiotherapy had a pathologic complete
response. At a median follow-up of 32 months, OS was significantly better with preoperative chemoradiotherapy (HR, 0.657; 95% CI, 0.495 to 0.871; 3-year survival rate, 58% vs. 44%).

3. Treatment of advanced (metastatic) disease. Similar systemic chemotherapy regimens are used for both EAC and ESCC. Various agents with modest activity when used alone are available. These include cisplatin, carboplatin, fluorouracil, bleomycin, paclitaxel, docetaxel, irinotecan, gemcitabine, methotrexate, mitomycin, vinorelbine, and doxorubicin. Response rates range from 15% to 30% and are usually brief. Most data are for ESCC, the exception being paclitaxel, which appears equally effective in both histologic types. The most active drugs appear to be platinum analogs, paclitaxel, and fluorouracil. Single agents are less helpful than doublet combination chemotherapy because of their lower response rates and brief duration of response. Approximately 7% to 22% of esophagogastric adenocarcinomas overexpress the type II epidermal growth factor receptor (EGFR) (HER2) and may benefit from trastuzumab, an anti-HER2 monoclonal antibody. The benefit of trastuzumab in advanced HER2-positive adenocarcinoma was studied in the phase III ToGA trial, which compared standard chemotherapy (six courses of cisplatin plus either infusional 5-fluorouracil [5-FU] or capecitabine) with and without trastuzumab (8 mg/kg loading dose, then 6 mg/kg every 3 weeks until disease progression). The objective response rate was significantly higher with trastuzumab (47% vs. 35%) and at a median follow-up of 17.1 to 18.6 months, OS was significantly better with trastuzumab (13.8 vs. 11.1 months).²³

Repeat every 28 days.

Repeat every 21 days.

Repeat every 21 days.

Repeat every 28 days.

Repeat every 6 weeks.

Repeat every 2 weeks.

Repeat every 2 weeks.

Repeat every 21 days.

Repeat every 2 weeks.

This may be chosen from the list of alternative combination therapies or the single agents, including single-agent docetaxel, paclitaxel, ramucirumab, or irinotecan. In the phase III REGARD trial, 355 patients with previously treated advanced or metastatic gastric or EGJ adenocarcinoma were randomly assigned
to best supportive care plus either ramucirumab or placebo, and although the benefit was small, it was shown that patients who received ramucirumab had better median progression-free survival (PFS) (2.1 vs. 1.3 months) and OS (5.2 vs. 3.8 months; HR, 0.78; 95% CI, 0.60 to 0.998).²⁴ In the phase III RAINBOW trial, patients were randomized to either weekly paclitaxel 80 mg/m² on days 1, 8, and 15 of 28-day cycle plus ramucirumab (8 mg/kg IV every 2 weeks) or placebo who had disease progression on or within 4 months after first-line platinum and fluoropyrimidine-based combination therapy, and median OS was significantly better with ramucirumab (9.6 vs. 7.4 months, HR 0.807, 95% CI, 0.678 to 0.962) as was PFS (4.4 vs. 2.9 months).²⁵ Combination therapy can be used depending on prior therapy and performance status.

Esophagitis during a combined-modality treatment program is nearly universal, and nutritional support frequently is required, preferably using alimentation by feeding tube placed by enterostomy. Peripheral alimentation is difficult with the continuous chemotherapy administration. Gastrostomy tubes are to be avoided in patients with potentially resectable lesions because of the usual requirement for a gastric pull-up after resection of the esophageal tumor.

The optimal surveillance strategy after local therapy of esophageal cancer remains unclear with little prospective data. For asymptomatic patients who have had potentially curative therapy, history and physical examination may be done every 3 to 6 months for years 1 to 3, every 6 months for years 3 to 5, and then annually. CT scans, endoscopy, chemistries, and complete blood count should be evaluated as clinically indicated.

The incidence of stomach cancer has decreased dramatically in the United States since the beginning of the century, although it has stabilized in the last 20 years. The incidence of gastric cancer varies geographically with the highest rates in Eastern Asia, Eastern Europe, and South America and lowest rates in North America and Africa.³ No improvement has been seen over the last two decades though, with 5-year survival rates ranging from 45% to 71% in node-negative disease to 5% to 30% in node-positive or metastatic disease. The male-to-female ratio is nearly 2:1. A high rate of chronic gastritis and intestinal metaplasia of the stomach is associated with a high incidence of gastric cancer. Helicobacter pylori has been implicated in such changes and in gastric cancer, particularly the more distal “intestinal” type, as well as in peptic ulcer disease. Other environmental factors such as a high-salt diet
and consumption of nitrates have been associated with a higher risk of gastric cancer.²⁶ Although the incidence in the United States has decreased, the location of gastric cancers has migrated proximally. Nearly half the stomach cancers occurring in white men are located proximally (GEJ, cardia, and proximal lesser curvature).

The most common symptoms are weight loss, abdominal pain, nausea, vomiting, changes in bowel habits, fatigue, anorexia, and dyspepsia. The diagnosis generally is made by endoscopy and biopsy, although barium swallow is frequently helpful. Staging of a suspected gastric cancer should initially include CT scans of the chest, abdomen, and pelvis. Endoscopic ultrasonography is increasingly used; it is more accurate in gauging the depth of the cancer in the gastric wall than in determining nodal involvement.²⁷ PET scans are more sensitive than CT scans for detection of distant metastases, and in one prospective study, integrated PET/CT identified otherwise radiographically occult metastatic lesions in 10% of patients with locally advanced tumors (larger than T3 lesions and N1 nodal involvement).²⁸ Laparoscopy can also improve clinical staging as it can more accurately identify peritoneal metastases and further evaluate the liver. Tumor markers such as carcinoembryonic antigen (CEA), cancer antigen (CA) 19-9, and CA 72-4 may be useful for subsequent assessment of the response to therapy. Prognosis is reflected by accurate staging. The revised staging method classifies patients according to the number of pathologically involved regional lymph nodes. The groupings are one to two (N1), three to six (N2), and seven or more involved lymph nodes (N3).

Most stomach cancers are adenocarcinomas. Important prognostic factors include tumor grade and gross appearance. Diffusely infiltrating lesions are less likely to be cured than sharply circumscribed, nonulcerating lesions. The presence of regional lymph node involvement or involvement of contiguous organs in the surgical specimen indicates an increased likelihood of recurrence, as does the presence of dysphagia at the time of diagnosis. Patients with proximal lesions or lesions requiring total, rather than distal subtotal, gastrectomy are also at greater risk.

There has been controversy as to the contribution of extensive lymphadenectomy (D1 vs. D2 dissection) to survival benefit. Japanese surgeons have widely promoted the D2 dissection; however, initial data from the randomized clinical trials including the Dutch Gastric Cancer Group²⁹ and the Medical Research Council trials³⁰ did not show a survival benefit of D2 over D1 lymphadenectomy and that there was increased morbidity and mortality for the patients who had D2 dissection. More recently, long-term data from the Dutch Gastric Cancer Group has now shown a survival benefit
of D2 dissection (15-year OS rate of 21% vs. 29%; p = 0.34) and that it is associated with lower rates of locoregional recurrence.³¹ Additionally, two other studies from Austria and Spain demonstrated better outcomes with D2 versus D1 dissections.³²,³³

Meta-analyses comparing adjuvant chemotherapy versus surgery alone have shown benefit to postoperative chemotherapy.³⁴ The optimal choice of adjuvant chemotherapy has not been established and acceptable options include epirubicin, cisplatin, and 5-FU (ECF) as used in the MAGIC trial³⁵ described later, or capecitabine and oxaliplatin as used in the CLASSIC trial.³⁶ In Asian patients, S-1³⁷ has been shown to improve both OS and relapse-free survival in patients with stage II or III gastric cancer who underwent a D2 gastrectomy.

Neoadjuvant and perioperative chemotherapy has also been used as a means to attempt downstaging of a locally advanced tumor prior to surgery. In 2006, the European MAGIC trial³⁵ was published which studied 503 patients with gastric cancer randomized to surgery alone versus three preoperative and three postoperative cycles of the ECF regimen. The patients who received chemotherapy demonstrated significant downstaging of their tumors with improved PFS (19 vs. 13 months; p = 0.0001), median survival (24 vs. 20 months; p = 0.02), and 5-year survival (36% vs. 23%; p = 0.009). Because only 55% of patients were able to begin postoperative therapy, it is postulated that the preoperative chemotherapy provided the most significant benefit. Other neoadjuvant regimens, including combinations with radiation, are undergoing study.

There have been three randomized trials of postoperative chemoradiation that have shown survival benefit when compared to surgery alone.³⁵,³⁸,³⁹,⁴⁰ The largest of these trials is the U.S. Gastrointestinal Intergroup³⁸ that has reported the results of a 556-patient randomized trial comparing surgery with or without postoperative chemotherapy (fluorouracil and leucovorin) and combined chemotherapy and radiation followed by two additional cycles of chemotherapy. Patients had resected stages IB through stage IV M0 adenocarcinoma of the stomach or GEJ. Postoperative combined therapy produced a statistically significant median survival benefit (36 vs. 27 months, respectively; p = 0.005). Although the study did not show any significant difference in relapse-free survival or OS according to the extent of lymph node dissection, 54% of patients had a D0 lymphadenectomy (surgery that did not remove all of the N1 nodes), 36% had a D1 dissection, and only 10% underwent a D2 dissection (includes perigastric, celiac, splenic, hepatic artery, and cardial lymph nodes). Major toxic effects (grade 3 or higher) in the
chemoradiotherapy group were predominantly hematologic (54%) and GI (33%).

Adjuvant chemoradiation has been directly compared to adjuvant chemotherapy in a number of trials, only one of which showed a significant OS benefit to chemoradiation. The largest of these trials, the ARTIST trial, randomized 458 patients with complete resected gastric cancer, D2 lymph node dissection to six courses of postoperative capecitabine plus cisplatin, or two courses of the same chemotherapy followed by chemoradiotherapy (45 Gy radiotherapy with concurrent daily capecitabine [825 mg/m² twice daily]) and two additional courses of chemotherapy).⁴¹ At a median follow-up of 84 months, 3-year disease-free survival (DFS) was not significantly better in patients who received chemoradiation (HR, 0.74; 95% CI, 0.52 to 1.05), although unplanned subset analysis did indicate a significantly better outcome with chemoradiotherapy in those with node-positive disease (3-year DFS, 76% vs. 72%; p = 0.004). OS, a secondary endpoint, was also not significantly different (HR, 1.13; 95% CI, 0.775 to 1.647).⁴² A meta-analysis of six trials concluded that while chemoradiotherapy was associated with significantly higher rates of 5-year DFS (odds ratio [OR], 1.56; 95% CI, 1.09 to 2.24) and significantly lower rates of locoregional recurrence (OR, 0.46; 95% CI, 0.32 to 0.67), there was only a trend toward a survival benefit for chemoradiotherapy that was not statistically significant (OR for OS, 1.32; 95% CI, 0.92 to 1.99).⁴³

The regimen is repeated every 21 days for three cycles preoperatively and three cycles postoperatively (if possible).

The regimen is repeated every 21 days.

In metastatic disease, there are data to support the OS, PFS, and response rate (RR) of cytotoxic chemotherapy when compared with best supportive care.

Agents with activity include epirubicin, mitomycin, doxorubicin, cisplatin, etoposide, fluorouracil, irinotecan, hydroxyurea, the taxanes, and the nitrosoureas. Single agents have low response rates (15% to 30%), brief durations of response, few complete responses, and little impact on survival.

Two drug regimens are more widely used than single agents, largely because of higher response rates, more frequent complete responses, and the potential of longer survival. Many combination therapies have benefits, including cisplatin plus 5-FU⁴⁴ or capecitabine,⁴⁵ anthracycline-containing regimens (ECF, EOX), taxane-based combinations (paclitaxel, docetaxel, DCF, or docetaxel plus capecitabine), oxaliplatin combinations (FOLFOX, CAPOX, EOF), and irinotecan-containing regimens (FOLFIRI).

The REAL trial was a landmark, large, randomized trial that compared four different chemotherapy regiments in over 1,000 patients with advanced gastric cancer. ECF, EC plus capecitabine, and epirubicin plus oxaliplatin and either infusional 5-FU (EOF) or capecitabine (EOX) were compared.⁴⁶ This trial showed that capecitabine can be substituted for infusional 5-FU. It also showed that outcomes are comparable when oxaliplatin is substituted for cisplatin in the ECF regimen. When the four groups were considered separately, median survival in patients treated with EOX was modestly longer when compared with ECF (median, 11.2 vs. 9.9 months; HR, 0.80; 95% CI, 0.66 to 0.97).

Approximately 7% to 22% of EGJ adenocarcinomas overexpress the type II EGFR (HER2). Trastuzumab is an anti-HER2 monoclonal antibody that has been U.S. Food and Drug Administration (FDA)-approved, in combination with cisplatin and a fluoropyrimidine, for the treatment of metastatic gastric or EGJ adenocarcinomas. The ToGA study was the first randomized, prospective, multicenter phase III study to evaluate the efficacy and safety of trastuzumab in patients with HER2-neu-positive
gastric and GEJ adenocarcinoma in combination with cisplatin and a fluoropyrimidine.²³ This study of 594 patients with HER2-neu-positive (3+ on immunohistochemistry [IHC] or fluorescence in situ hybridization [FISH]-positive) locally advanced, recurrent, or metastatic gastric and EGJ adenocarcinoma were randomized to trastuzumab plus chemotherapy versus chemotherapy alone. The majority of the patients in this trial had gastric cancer. There was a significant improvement in the median OS (13.8 vs. 11 months, respectively; p = 0.46) with the addition of trastuzumab to chemotherapy.

Angiogenesis inhibitor has been explored in metastatic gastric cancer. The Avastin in Gastric Cancer (AVAGAST)⁴⁷ was a multinational, randomized, placebo-controlled trial that evaluated the efficacy of adding bevacizumab, a vascular endothelial growth factor (VEGF) inhibitor, to capecitabine and cisplatin in the first-line treatment of advanced gastric cancer. This trial of 774 patients did not meet its primary OS endpoint, but the progression free survival and overall response rate did favor bevacizumab. There was suggestion that there may be variation in OS benefit based on geographic location, with little benefit in Asian patients (also seen in China study) but there was a benefit in Pan-American population; however, this was just an exploratory analysis. Bevacizumab is not FDA-approved for metastatic gastric cancer, and its use is not endorsed by guidelines such as National Comprehensive Cancer Network (NCCN) guidelines.

Ramucirumab³⁷ is a fully humanized VEGF receptor 2 (VEGFR-2) antibody. In the first-line setting, the efficacy of ramucirumab in esophagus, GEJ, and gastric in combination with FOLFOX has been evaluated.⁴⁸ This study did not meet its OS endpoint in all patients, but there was suggestion of improvement in the gastric/GEJ subset and there will be an ongoing trial exploring this further. The REGARD trial randomized 355 patients with advanced gastric of EGJ adenocarcinoma after progression on first-line therapy to RAM versus placebo.⁴⁹ Median OS was 5.2 months in the patients treated with RAM compared to 3.8 months in the placebo group (p = 0.47). RAM was associated with higher rates of hypertension than in the placebo group (16% vs. 8%), but other adverse events were similar in the two groups. The RAINBOW trial evaluated paclitaxel with or without RAM in patients with metastatic gastric or EGJ adenocarcinoma progressing on first-line chemotherapy.⁵⁰ In this study of 665 patients, the median OS was significantly longer for the RAM plus paclitaxel group compared to the paclitaxel alone (9.63 vs. 7.36 months; p < 0.0001). The ORR favored RAM plus paclitaxel
versus paclitaxel alone (28% vs. 16%; p = 0.0001). RAM was well tolerated with increased rate of bleeding, neutropenia, and hypertension in the combination group. This study led to FDA-approval of RAM with paclitaxel, and this can be considered in patients after progression in addition to other second-line therapies. Apatinib (anti-VEGFR-2 tyrosine kinase inhibitor [TKI]) has been studied in Chinese patients with advanced third-line gastric cancer and randomized to apatinib versus placebo, and preliminary results showed modest improvement in OS and is currently approved in China.⁵¹

A variety of investigational agents including MET inhibitors, PD-1 inhibitor, and other immune-checkpoint inhibitors have early-phase data that may be encouraging; however, definitive results of ongoing studies are needed.