A Phase II Trial of GM-CSF Plus Maintenance Pembrolizumab +/- Pemetrexed After Completion of First Line Chemo-Immunotherapy in Advanced Non-Small Cell Lung Cancer Patients with PDL-1 of 1%-49%

Lung cancer is the most commonly diagnosed cancer worldwide. Metastatic lung cancer is the leading cause of cancer mortality worldwide with a 5-year survival of less than 5%. With the approval of programmed cell death 1 (PD-1) inhibitors in advanced lung cancer, there has been an improvement in overall response rates and survival compared to chemotherapy.

Checkpoint inhibition has become a primary treatment modality for vast number of cancers including lung cancer, prolonging survival in some patients. However, an important consideration is how to best select those patients who will respond to checkpoint inhibition. The biomarker that has been studied most extensively is PD-L1 expression. Studies have shown trends for increased response rates to PD-1 blockade in PD-L1 positive tumors.

NSCLC patients are now approved for pembrolizumab monotherapy (PDL-1>1%) or for pembrolizumab in combination with chemotherapy (carboplatin/pemetrexed for non-squamous or carboplatin/paclitaxel) (no minimum PDL-1). As the ORR and PFS in both these trials indicate, however, there is a need for improvement in response rates and PFS in first-line treatments for patients with stage 4 NSCLC without genetically targetable alterations especially in those patients with PDL-1 <50%.

There are both pre-clinical and clinical evidence supporting the combination of granulocyte macrophage colony stimulating factor (GM-CSF) with immunotherapy. GM-CSF is a hematopoietic growth factor that triggers proliferation and differentiation of hematopoietic progenitor cells, mainly neutrophils, monocytes/macrophages and myeloid-derived dendritic cells, and is approved by the FDA for this purpose.

A phase II randomized clinical trial of unresectable stage III or IV melanoma patients comparing the effects of ipilimumab plus GM-CSF vs ipilimumab alone was shown to be both safe and had longer overall survival with lower toxicity than immunotherapy alone; 1 year survival for ipilimumab plus sargramostim was 68.9% (95% CI, 60.6%-85.5%) compared to 52.9% (95% CI, 43.6%-62.2%) for ipilimumab alone.