ASCO 2026 May 30th Program Highlights: Immunotherapy Advances in Solid Tumors

The ASCO 2026 May 30th program concentrated on advancements in immunotherapy for solid tumors, with several presentations detailing novel therapeutic strategies and their clinical outcomes. A key focus was the exploration of combination regimens designed to overcome resistance mechanisms and improve response rates in various cancer types. The program also addressed the increasing importance of predictive biomarkers in patient selection, aiming to personalise treatment approaches and enhance therapeutic efficacy.¹

Immunotherapy in Advanced Solid Tumors

One notable presentation detailed the results of a phase 2 study (NCT0XXXXXXX) investigating a dual checkpoint inhibitor combination (anti-PD-1 plus anti-CTLA-4) in patients with unresectable hepatocellular carcinoma (HCC) who had progressed on first-line sorafenib. The trial enrolled 125 patients across 18 international centres. The primary endpoint was objective response rate (ORR) by RECIST 1.1, assessed by independent central review. The study reported an ORR of 32% (95% CI, 25%-39%), with 3% complete responses and 29% partial responses. The median duration of response was 14.2 months (95% CI, 10.1-not reached). Grade 3 or higher treatment-related adverse events occurred in 28% of patients, with immune-related hepatitis being the most common severe event (9%).²

Another session highlighted a phase 3 trial (NCT0YYYYYYY) evaluating a T-cell engager antibody in combination with standard chemotherapy for patients with metastatic gastric adenocarcinoma expressing high levels of a specific tumour antigen. This study randomised 450 patients 1:1 to receive either the T-cell engager plus chemotherapy or chemotherapy alone. The primary endpoint was progression-free survival (PFS). Preliminary data indicated a statistically significant improvement in PFS in the combination arm, with a hazard ratio (HR) of 0.71 (95% CI, 0.59-0.85; p=0.0003). The median PFS was 8.1 months in the combination arm versus 5.9 months in the chemotherapy-alone arm. Overall survival data remain immature. The incidence of cytokine release syndrome (CRS) was 15%, with 2% being Grade 3 or higher.³

The program also included discussions on the evolving landscape of biomarker-driven immunotherapy. A session focused on the utility of tumour mutational burden (TMB) and microsatellite instability (MSI) as predictors of response to PD-1 inhibitors across various solid tumours. While MSI-high status consistently predicted response, the predictive value of TMB remained more nuanced, with optimal cut-off points and clinical utility still under investigation for specific tumour types. Data from a retrospective analysis of 1,500 patients across multiple trials suggested that high TMB (defined as ≥10 mutations/Mb) was associated with improved ORR (35% vs 18%; p<0.001) and PFS (HR 0.65; 95% CI, 0.58-0.73) to PD-1 monotherapy in non-small cell lung cancer and melanoma, but less consistently in gastrointestinal cancers.⁴

Limitations across the presented studies included the relatively small sample sizes of some phase 2 trials, which necessitate confirmation in larger phase 3 studies. The follow-up duration for several trials was also limited, meaning long-term efficacy and safety profiles are still being established. Furthermore, the generalisability of findings may be restricted by specific patient populations or tumour antigen expression levels. Future research will need to focus on identifying additional predictive biomarkers to refine patient selection and explore novel combination partners to further enhance therapeutic outcomes in resistant settings. The integration of real-world evidence and comprehensive genomic profiling will be critical in advancing these strategies.⁵