Second-line tislelizumab improves OS in advanced/metastatic ESCC in European/North American subgroup

Second-line treatment with tislelizumab improves overall survival (OS) in patients from Europe/North America (EU/NA) with advanced or metastatic oesophageal squamous cell carcinoma (ESCC) compared with chemotherapy, according to subgroup analysis of the RATIONALE 302* study presented at ESMO GI 2021.

“Tislelizumab represents a potential new second-line treatment option for patients with advanced ESCC globally,” said lead author Dr Jaffer Ajani from the University of Texas MD Anderson Cancer Center in Houston, Texas, US.

The phase III study involved 512 patients (overall population) with advanced/metastatic ESCC who had progressed during or after first-line treatment. Of these, 108 were from EU/NA subgroup. Participants were randomized to receive tislelizumab 200 mg intravenously every 3 weeks (overall cohort: n=256; EU/NA cohort: n=55) or investigator’s choice of chemotherapy** (overall cohort: n=256; EU/NA cohort: n=53). Patients continued treatment until disease progression or intolerable toxicity. [ESMO GI 2021, abstract O-15]

At a median follow-up of 6.9 months, median OS in the overall population was significantly longer among patients treated with tislelizumab vs chemotherapy (8.6 vs 6.3 months; hazard ratio [HR], 0.70; one-sided p<0.0001)

At a median follow-up of 6.8 months for the EU/NA subgroup, median OS was longer among patients in the tislelizumab vs the chemotherapy arm (11.2 vs 6.3 months; HR, 0.55).

“[These results] turned out to be better than the overall population,” Ajani noted.

Moreover, the 12-month OS rate in the EU/NA subgroup was higher among tislelizumab-treated patients than chemotherapy-treated patients (42.7 percent vs 17.6 percent).

A higher overall response rate was observed among patients treated with tislelizumab compared with chemotherapy in both the overall population (20.3 percent vs 9.8 percent; odds ratio [OR], 2.4) and EU/NA subgroup (20.0 percent vs 11.3 percent; OR, 2.0).

Tislelizumab recipients also demonstrated a longer median duration of response compared with chemotherapy recipients in both cohorts (7.1 vs 4.0 months [overall population] and 5.1 vs 2.1 months [EU/NA subgroup]).

Grade 3–5 treatment-emergent adverse events occurred at a lower rate in the tislelizumab vs chemotherapy arm for both the overall population (46.3 percent vs 67.9 percent) and EU/NA subgroup (55.6 percent vs 71.4 percent).

“[Overall, second-line] tislelizumab demonstrated statistically significant and clinically meaningful improvement in OS vs chemotherapy in patients with advanced or metastatic ESCC,” said Ajani. [This OS benefit] was consistently observed in patients from the EU/NA subgroup.”

“Tislelizumab showed a higher and more durable antitumour response … [with] a tolerable safety profile compared with chemotherapy in the overall population … [that was also] consistent in the EU/NA subgroup,” he added.

*RATIONALE 302: A study of tislelizumab (BGB-A317) versus chemotherapy as second line treatment in participants with advanced esophageal squamous cell carcinoma

**Investigator-chosen chemotherapy: Paclitaxel 137–175 mg/m² IV Q3W or 80–100 mg/m² IV QW, docetaxel 75 mg/m² IV Q3W, or irinotecan 125 mg/m² IV on days 1 and 8 Q3W