A lung squamous cell carcinoma-associated membranous nephropathy patient free of tumor and membranous nephropathy after the treatment of surgery and radiochemotherapy following pembrolizumab: A rare case report.

RATIONALE

Membranous nephropathy (MN) is an autoimmune disease, which is classified into primary and secondary MN. Malignancy-associated MN (M-MN) accounts for about 10% of secondary MN cases. Lung cancer is the most common type of malignancy among M-MN patients. Immune checkpoint inhibitors (ICIs) targeting programmed cell death-1 (PD-1) or programmed cell death ligand-1 (PD-L1) have showed promising efficacy and good safety in many types of solid tumors, including non-small cell lung cancer. To date, whether ICIs could be a treatment option for M-MN patients with PD-L1 expression and or high tumor mutation burden (TMB) level has not been documented.

PATIENT CONCERNS

A 68-year-old male patient presented with edema of the lower limbs with increased urine foam in August 2018. Biopsy on the right kidney showed MN at stage I with subepithelially localized immune deposits.

DIAGNOSIS

Lung squamous cell carcinoma (LSCC)-associated MN with PD-L1 expression (20%) and high TMB level (26.2 mutations/Mb).

INTERVENTIONS

The patient received immunosuppressive therapy targeting the initially diagnosed primary MN as first-line treatment plus surgery and radiochemotherapy following pembrolizumab targeting the definitively diagnosed lung cancer as second-line treatment.

OUTCOMES

The patient benefited from radiochemotherapy following pembrolizumab (lasting more than 38 months) rather than immunosuppressive therapy.

LESSONS

Our work suggests that combined ICIs might be an effective treatment option for M-MN patients who harbor PD-L1 expression. Our work highlights that the presence of malignancy should not be neglected at the initial diagnosis of MN.