Haematological toxicity of pemetrexed in patients with metastatic non-squamous non-small cell carcinoma of lung with third-space fluid

Background: Pemetrexed was approved by United States Food and Drug Administration (US FDA) in combination with platinum for the treatment of advanced non-squamous non-small cell lung carcinoma (NSCLC) and malignant mesothelioma. Due to the structural similarity with methotrexate, there has been concern about the accumulation of pemetrexed in third space fluid that may result in increased toxicity. Previous small-scale studies have yet to conclusively prove this association. Methods: This was a retrospective single-center cohort study conducted in Queen Mary Hospital in Hong Kong. The study included 329 patients with advanced stage non-squamous NSCLC that received first line pemetrexed and platinum. Patients who had non-evacuated third-space fluid, evacuated third-space fluid and without third space fluid were compared. The primary endpoint was the occurrence of hematological toxicity. Results: The presence of non-evacuated third-space fluid was shown to be associated with significantly more hematological toxicities, namely grade 3 or above hematological toxicities [Odd ratio (OR) = 2.450, p = 0.002], postponement of chemotherapy (OR = 3.837, p = 0.000) and need for dose adjustment (OR = 2.436, p = 0.022) when compared with those without third-space fluid. For patients with evacuated third-space fluid, these adverse effects were nullified. Conclusions: Presence of non-evacuated third-space fluid in patients with advanced non-squamous NSCLC predispose patients to significant hematological toxicity when pemetrexed and platinum chemotherapy is used. Evacuation of third-space fluid should be considered before starting pemetrexed and platinum doublet.

Automated summary

The presence of non-evacuated third-space fluid in patients with advanced non-squamous NSCLC increases the risk of hematological toxicity when receiving Pemetrexed and platinum chemotherapy. Evacuation of third-space fluid in these patients can mitigate these adverse effects.