161P - PDL1 expression and its relation to EML4-ALK gene variants in metastatic lung adenocarcinoma: A single-center real-world experience

Background

Targeted therapy and Immunotherapy have revolutionized the treatment of metastatic non-small cell lung cancer (NSCLC), particularly adenocarcinoma (AC). Among NSCLC cases, around 8-10% are ALK positive with the majority involving EML4-ALK gene variants. This study aims to explore the connection between ALK gene variants and PDL1 expression in metastatic lung AC, as there is limited data from the Indian cohort on this subject.

Methods

A retrospective analysis was conducted on data collected from 17 advanced lung AC patients with ALK gene mutations. The ALK protein variants were determined through Next-Generation Sequencing, while PDL1 expression was assessed using Immunohistochemistry with sP263 antibody. These findings were then correlated with relevant clinical parameters.

Results

The median age of the patient cohort was 46 years (range 28 to 65). Among the 17 ALK-positive, the majority had EML4-ALK gene fusions, with V1 (47.05%), V3 (35.2%), and V2 (11.7%) being the most common variants. V1 was more prevalent in females (87.5%) than males (12.5%). PDL1 negativity was observed in 64.7% of patients, while 35.2% were PDL1 positive. Specifically, PDL1 negativity was more common in the V1 variant, whereas PDL1 positivity was associated with V3. Brain metastases were more frequent in the PDL1-negative cohort (35.2%), and bone metastases and malignant pleural effusions were more common in V1 compared to V2 and V3. Table: 161P

Conclusions

The study concludes that V1 and V3 EML4-ALK gene variants are prevalent in metastatic lung AC patients. It reveals a significant association between PDL1 expression and specific ALK variants, with V1 being more frequently associated with PDL1 negativity and V3 with PDL1 positivity. Additionally, the V1 and V3 variants were more commonly found in female patients and were associated with brain metastases. This real-world experience contributes valuable insights into treatment responses in this specific patient population.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.