Ken Kodama*, Toru Momozane, Hiroshi Takehara, Junko Tanizaki and Kazuaki Sato
Introduction: To date, there have been few reports of Non-Small Cell Lung Cancer (NSCLC) cases where a single cycle of pembrolizumab monotherapy led to near-complete tumor resolution without any adverse events.
Case Presentation: A 57-year-old woman with clinical stage IVB NSCLC and high Programmed Cell Death ligand 1 (PD-L1) expression of 95% received first-line pembrolizumab monotherapy. After only one cycle of the therapy, she experienced a significant improvement in respiratory symptoms and showed a nearly complete tumor response on CT. To date, the patient has received 15 cycles of pembrolizumab and sustained a complete response without any immune or treatment-related adverse events for 15 months.
Conclusion: Our literature search yielded 11 similar case reports in addition to this report. According to them, the mechanism of such rapid tumor disappearance after pembrolizumab monotherapy remains unclear; however, close attention should be paid to fatal hemoptysis as a treatment-related adverse event, if the patient shows hilar or mediastinal lesions with suspected vascular invasion on baseline CT.