1423P - Clinical impact of radiological diagnosis of lymphangitic carcinomatosis in patients with extensive non-small cell lung cancer treated with immunotherapy

Background

Lymphangitic carcinomatosis (LC) is a pathological feature secondary to lymphatic or haematological spread, without an immune cell infiltrate but with radiological appearances of inflammation. Immunotherapy (IO) is now standard of care in early and late-stage non-small cell lung cancer (NSCLC). LC correlates with poor prognosis, but its effects on immunotherapy response are unknown. Here we aim to explore the predictive relevance of the radiological diagnosis of LC in patients with advanced NSCLC treated with single agent immunotherapy (SAIO) or with chemo-immunotherapy (CIO).

Methods

Demographic and clinical data of patients treated with first-line IO between January 2016 and December 2020 was retrospectively collected, and patients with LC identified using pre-treatment CT reports. A paired control arm matched for gender, age (≤70 or >70), smoking status, PS, PDL1 (<1%, 1-49% and ≥50%), stage and treatment was used to compare clinical outcomes. Chi-square Log-Rank (Mantel-Cox) test was used to compare Progression-Free Survival (PFS) and Overall Survival (OS).

Results

A total of 484 patients had been treated with first-line SAIO or CIO, 46 (10.6%) with LC. 41 of them (89%) had non-squamous histology. 29 (63%) were treated with SIAO and 17 (37%) with CIO. Comparing tumours with LC versus the rest, PDL1 expression was <1%; 24 vs 11%, 1-49%; 9 vs 11% and ≥50%; 65 vs 71%. Grade 3/4 IO toxicity rates were similar (48% vs 45%). Comparing patients with LC versus a paired control population (n=73), overall response rates were 28% vs 56%, with disease progression rates of 37 vs 25%. Median PFS was 5 vs 9 months (HR 1.57, 95% C.I. 1.054 – 2.35, p=0.019) and median OS was 9 vs 17 months (HR 1.49, 95% C.I. 0.995 – 2.224, p=0.046). Brain metastases on progression were more common in patients with LC (20% vs 8%). Using univariate Cox regression analysis, PFS and OS were not influenced by the treatment received (SAIO or CIO).

Conclusions

Lymphangitis Carcinomatosis (LC) in patients with NSCLC treated with immunotherapy correlated with lower response rates, poorer PFS and OS. Addition of chemotherapy did not improve outcomes. LC may represent a pre-treatment marker of primary resistance to immunotherapy.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The Clatterbridge Cancer Centre.

Funding

Has not received any funding.

Disclosure

C. Escriu: Financial Interests, Personal, Advisory Board: MSD, Roche; Financial Interests, Personal, Invited Speaker: MSD, Roche. All other authors have declared no conflicts of interest.