76P - Fixed 2-year vs. continuous duration immune checkpoint inhibitors in patients diagnosed with advanced cancer: to continue or not to continue?

Background

The optimal duration of immune checkpoint inhibitors (ICIs) in advanced solid malignancies is unknown. Subsets of patients who experience immune related adverse events (irAEs) maintain durable responses despite limited ICI exposure. When ICI discontinuation isn’t prompted by progressive disease (PD) or irAEs it could potentially be given indefinitely. In numerous sponsor-initiated trials the duration of ICI was fixed at 2-years. In a tertiary cancer centre, we report the real-world practices surrounding stopping or continuing ICIs beyond 2 years in patients diagnosed with advanced cancer.

Methods

A retrospective data analysis was performed at a specialist cancer centre. Patients diagnosed with a stage IV solid tumour, who received ICI for at least 2 years from January 2016 to September 2024, were included.

Results

In total 170 patients received at least 2 years of ICI, 156 were evaluable. At 2 years, 61 patients stopped ICI (FIXED) & 95 continued (CONTD). Patients in the CONTD group continued ICI for a median of 61 weeks (range 13-271) beyond 2 years. Twenty-seven (28%), 16 (17%) and 10 (11%) patients discontinued ICI in years 3, 4 & 5-onwards respectively while 42 (44%) were still receiving ICI at time of reporting. 27 (44%) patients in FIXED and 34 (36%) in CONTD developed PD post 2 years (p=0.3). Median time from 2-year point to PD was 28 months in FIXED and hadn’t been reached in CONTD (p=0.2). OS was 38 & 52 months in FIXED & CONTD respectively (p=0.06). Table: 76P

Calculated with Chi-Square test. NS = not significant p>0.05

Conclusions

Without evidence to guide practice there is significant heterogenicity in the duration of ICI in patients with advanced solid malignancies. Continuation of ICI was not influenced by best response but was influenced by tumour type (Table 1). There was a trend towards increased survival in the CONTD group but this was not significant.

Legal entity responsible for the study

The authors, the Chrisite NHS Foundation Trust.

Funding

Has not received any funding.

Disclosure

N. Cook: Financial Interests, Personal, Invited Speaker: Roche; Financial Interests, Institutional, Local PI: Taiho, Roche, AstraZeneca, Avacta, Bayer, Eisai, UCB, Boehringer; Financial Interests, Institutional, Coordinating PI: RedX, Orion, Starpharma, Loxo-Oncology; Non-Financial Interests, Personal, Advisory Role: Roche; Non-Financial Interests, Personal, Other, Committee chair: Cancer Research UK. All other authors have declared no conflicts of interest.