Pembrolizumab for the treatment of programmed death-ligand 1-positive advanced carcinoid or pancreatic neuroendocrine tumors: Results from the KEYNOTE-028 study

Cancer. 2020 Jul 1;126(13):3021-3030. doi: 10.1002/cncr.32883. Epub 2020 Apr 22.


Background: Despite a protracted disease course and multiple available therapies, patients with well-differentiated neuroendocrine tumors (NETs) inevitably experience disease progression. Programmed death-ligand 1 (PD-L1) has been associated with NET progression and prognosis. The multicohort, phase 1 KEYNOTE-028 study ( identifier NCT02054806) evaluated the activity and safety of the anti-programmed cell death protein 1 immunotherapy pembrolizumab in patients with well-differentiated or moderately-differentiated NETs.

Methods: Patients with PD-L1-positive, locally advanced or metastatic carcinoid or well-differentiated or moderately-differentiated pancreatic NETs (pNETs) were enrolled into separate cohorts and received pembrolizumab at a dose of 10 mg/kg every 2 weeks for up to 2 years. The objective response rate was the primary endpoint (as per Response Evaluation Criteria in Solid Tumors version 1.1, by investigator review). Safety was a secondary endpoint.

Results: Of 170 and 106 patients, respectively, who had evaluable samples among those screened for the carcinoid and pNET cohorts, 21% and 25%, respectively, had PD-L1-positive tumors; of these, 25 and 16 patients, respectively, were eligible and treated. The median follow-up was 20 months (range, 2-35 months) and 21 months (range, 5-32 months), respectively. The objective response rate was 12.0% (95% CI, 2.5%-31.2%) and 6.3% (95% CI, 0.2%-30.2%), respectively; 3 partial responses occurred among the carcinoid cohort and 1 among the pNET cohort. The median duration of response in the carcinoid cohort was 9.2 months (range, 6.9-11.1 months), and was not reached in the pNET cohort. No complete responses occurred. Treatment-related adverse events occurred in 68% and 69% of patients, respectively, most often diarrhea (7 patients in the carcinoid cohort and 4 patients in the pNET cohort) and fatigue (6 patients in each cohort). Hypothyroidism was the most common immune-mediated adverse event (5 patients in the carcinoid cohort and 2 patients in the pNET cohort).

Conclusions: Pembrolizumab demonstrated antitumor activity in a subset of patients with NETs and was well-tolerated.

Keywords: KEYNOTE-028; antitumor activity; carcinoid tumors; immunotherapy; pancreatic neuroendocrine tumors; pembrolizumab; programmed death-ligand 1.

Publication types

  • Clinical Trial, Phase I
  • Multicenter Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Alanine Transaminase / metabolism
  • Antibodies, Monoclonal, Humanized / administration & dosage
  • Antibodies, Monoclonal, Humanized / adverse effects
  • Antibodies, Monoclonal, Humanized / therapeutic use*
  • Antineoplastic Agents, Immunological / administration & dosage
  • Antineoplastic Agents, Immunological / adverse effects
  • Antineoplastic Agents, Immunological / therapeutic use*
  • Aspartate Aminotransferases / metabolism
  • Carcinoid Tumor / chemistry
  • Carcinoid Tumor / drug therapy*
  • Carcinoid Tumor / pathology
  • Cohort Studies
  • Diarrhea / chemically induced
  • Disease Progression
  • Drug Administration Schedule
  • Fatigue / chemically induced
  • Female
  • Follow-Up Studies
  • Humans
  • Hypothyroidism / chemically induced
  • Male
  • Middle Aged
  • Neuroendocrine Tumors / chemistry
  • Neuroendocrine Tumors / drug therapy*
  • Neuroendocrine Tumors / pathology
  • Pancreatic Neoplasms / chemistry
  • Pancreatic Neoplasms / drug therapy*
  • Pancreatic Neoplasms / pathology
  • Programmed Cell Death 1 Receptor / antagonists & inhibitors*


  • Antibodies, Monoclonal, Humanized
  • Antineoplastic Agents, Immunological
  • PDCD1 protein, human
  • Programmed Cell Death 1 Receptor
  • pembrolizumab
  • Aspartate Aminotransferases
  • Alanine Transaminase

Associated data