New results from the phase III RATIONALE 306 trial show that tislelizumab plus chemotherapy significantly improved overall survival (OS) as a first-line treatment for adult patients with unresectable, locally advanced or metastatic oesophageal squamous cell carcinoma (ESCC), regardless of PD-L1 status.

Tislelizumab plus chemotherapy demonstrated a median OS of 17.2 months (CI, 15.8-20.1 months) versus 10.6 months (CI, 9.3-12.1 months) in patients receiving chemotherapy plus placebo and reduced the risk of death by 34% (hazard ratio=0.66; CI, 0.54-0.80, p<0.0001).

The data was presented during a late-breaking oral session at the 2022 European Society for Medical Oncology (ESMO) World Congress on Gastrointestinal Cancer (Abstract #LBA-1).

“These data, which show tislelizumab plus chemotherapy extended patients’ lives by a median of more than six months, are a promising outcome in the treatment of this aggressive cancer,” said Dr. Ken Kato, Chief of Head and Neck Medical Oncology, National Cancer Center Hospital, Tokyo, Japan.

“Importantly, the significant overall survival benefit was observed across all patient subgroups in the trial, indicating that tislelizumab plus chemotherapy may be a viable treatment option for patients regardless of their PD-L1 score.”

In patients with PD-L1 score ≥10% (secondary endpoint), tislelizumab plus chemotherapy showed a median OS of 16.6 months (CI, 15.3-24.4 months) versus 10.0 months (CI, 8.6-13.0 months) in patients receiving chemotherapy plus placebo and reduced risk of death by 38% (HR=0.62; CI, 0.44-0.86, p=0.0020).

In those with PD-L1 score <10% (exploratory analysis), median OS with tislelizumab plus chemotherapy was 16.7 months (CI, 13.0-20.1 months) versus 10.4 months (CI, 9.1-13.0 months; HR=0.72; CI, 0.55-0.94). Survival benefit was consistent across all other subgroups, including race, geographical region and investigator choice of chemotherapy.

Tislelizumab plus chemotherapy also significantly improved progression-free survival (7.3 months vs 5.6 months; HR=0.62; CI, 0.52-0.75, p<0.0001) and objective response rate (63.5% vs 42.4%; odds ratio=2.38, p<0.0001).

“The prognosis for ESCC remains poor, with a five-year survival rate of just five percent, and patients are in need of more treatment options, especially in earlier lines of therapy,” said Jeff Legos, Executive Vice President, Global Head of Oncology & Hematology Development, Novartis.

“These results add to the growing body of evidence demonstrating the potential for tislelizumab to help patients with oesophagus cancer, and reinforce our commitment to studying tislelizumab alone and in synergistic combinations across additional tumour types that may benefit from an immunotherapy.”

The incidence of treatment-related adverse events (TRAEs) was similar in both arms.

Most common TRAEs for tislelizumab plus chemotherapy versus chemotherapy were anaemia (68% vs 61%), decreased neutrophils (78% vs 80%), decreased white blood cell count (55% vs 65%), decreased appetite (39% vs 38%), nausea (37% vs 42%) and peripheral sensory neuropathy (26% vs 21%).

ESCC is the most common type of esophageal cancer globally, with an estimated 604,000 new cases and 544,000 deaths from oesophageal cancer internationally in 2020.

In the United States, it is estimated there will be more than 20,000 new diagnoses and more than 16,000 deaths from oesophageal cancers.

RATIONALE 306 (NCT03783442) is a multi-regional Phase III, randomized, placebo-controlled, double-blind study of tislelizumab in combination with chemotherapy versus chemotherapy in patients with unresectable, locally advanced recurrent or metastatic ESCC.

Approximately 649 study participants were randomized 1:1 to receive either tislelizumab plus chemotherapy or chemotherapy plus placebo.

The primary endpoint is OS in the all-comer intent-to-treat population.

Secondary endpoints include OS in patients with PD-L1 score ≥10%, progression-free survival, objective response rate, duration of response, health-related quality of life measures and safety.

Source: Novartis