Tislelizumab Improves Overall Survival in Certain Types of Esophageal Cancer


Results of the phase 3 RATIONALE 203 study were presented at the 2021 ASCO Annual Meeting.

Investigational checkpoint inhibitor tislelizumab met the primary end point of overall survival (OS) in the phase 3 RATIONALE 302 study of esophageal cancer after systemic therapy. The study results were presented at the 2021 American Society of Clinical Oncology (ASCO) Annual Meeting on June 4, 2021.1

Tislelizumab, an anti-PD-1 immune checkpoint inhibitor, was evaluated in comparison with chemotherapy in patients with unresectable recurrent locally advanced or metastatic esophageal squamous cell carcinoma (ESCC) who had received prior systemic therapy. Tislelizumab was specifically engineered to minimize binding to macrophage Fcγ receptors.1

The primary end point of the study was OS in the intent-to-treat population. The key secondary end point is OS in PD-L1 positive patients, an additional secondary end points include progression-free survival (PFS), objective response rate (ORR), duration of response (DoR), and safety end points.1

The results of the study demonstrated the following1:

  • Treatment with tislelizumab demonstrated a 30% reduction in the risk of death and extended median OS by 2.3 months compared with chemotherapy.
  • Tislelizumab showed a median PFS of 1.6 months compared with 2.1 months (HR=0.83, 95% CI: 0.67-1.01).
  • Tislelizumab demonstrated a higher and more durable anti-tumor activity than chemotherapy (ORR, 20.3% vs 9.8%; median DoR, 7.1 months vs 4.0 months).

The study investigators also reported tislelizumab-treated patients experienced a lower (6.7%) discontinuation rate due to treatment-related adverse events (TRAEs) compared with chemotherapy-treated patients (13.8%). The most common all-grade TRAEs reported with tislelizumab were increased aspartate aminotransferase (11.4%), anemia (11%), and hypothyroidism (10.2%). No new safety signals were identified.1

“Most patients with this type of esophageal cancer are diagnosed with advanced disease, resulting in a poor prognosis for this difficult-to-treat cancer,” said Jaffer Ajani, MD, professor of gastrointestinal medical oncology at The University of Texas MD Anderson Cancer Center.2 “The impact tislelizumab had on survival compared to chemotherapy in this study is highly meaningful and encouraging news for patients, caregivers, and treating oncologists.”

Tislelizumab is also being evaluated in patients with previously treated, locally advanced, unresectable, or metastatic microsatellite instability-high and mismatch repair-deficient cancers in the RATIONALE 209 study. Study investigators reported that tislelizumab showed durable anti-tumor activity in this patient population.2


  1. Shen L, Kato K, Sun-Bae K, Ajani JA, et al. RATIONALE 302: Randomized, phase 3 study of tislelizumab versus chemotherapy as second-line treatment for advanced unresectable/metastatic esophageal squamous cell carcinoma. Presented at: 2021 American Society of Clinical Oncology Annual Meeting; June 4, 2021; virtual. Accessed June 4, 2021.
  2. Novartis investigational checkpoint inhibitor tislelizumab met primary endpoint of overall survival in pivotal Phase III trial of esophageal cancer after systemic therapy. News Release. Novartis; June 4, 2021. Accessed June 4, 2021. https://www.novartis.com/news/media-releases/novartis-investigational-checkpoint-inhibitor-tislelizumab-met-primary-endpoint-overall-survival-pivotal-phase-iii-trial-esophageal-cancer-after-systemic
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