S2686 A Rare Case of Atezolizumab-Induced Hepatotoxicity

Abstract

INTRODUCTION: Small cell lung carcinoma (SCLC) is typically seen in heavy smokers with a median survival of 8–13 months in extensive-stage disease. There is no standardized chemotherapy regimen, but randomized clinical trials with simultaneous chemotherapy agents have demonstrated survival benefits. Atezolizumab, a programed-cell death 1 (PD-L1) checkpoint inhibitor, is used in metastatic SCLC refractory to initial chemotherapy. We present a case of immune-related adverse event (irAE) with Atezolizumab-induced hepatotoxicity. CASE DESCRIPTION/METHODS: 70-year old male with extensive SCLC presented with right-upper quadrant abdominal pain. Approximately eighteen months ago, a screening CT Chest showed a 1.8 × 1.1 cm left upper lobe lung nodule. PET scan showed a hypermetabolic nodule concerning for primary neoplasm with hypermetabolic left hilar lymph nodes. CT-guided lung biopsy was consistent with small cell carcinoma with tumor cells expressing CK7, CD56, TTF-1, Synaptophysin, and Chromogranin. One month later, PET scan demonstrated progression of the hypermetabolic lung mass and left hilar lymphadenopathy with a new right rib focus concerning for distant metastasis. Oncology treated patient with 4 cycles of carboplatin/etoposide and maintenance treatment with monthly Atezolizumab. On admission, patient was hemodynamically stable. Initial labs included AST: 95, ALT: 91, Alkaline Phosphatase: 225, and Total Bilirubin: 1.8 (Direct Bilirubin 1.3). CTA Chest was negative for pulmonary embolism. MRI liver showed cirrhosis with a stable 1.6 wedge-shaped subcapsular benign lesion. Physical exam was notable for right-upper quadrant pain with palpation and non-distended reducible hernia. Additional labs showed normal immunoglobulins (IgG, IgM, IgA), negative hepatitis panel, negative actin anti-smooth muscle IgG, normal creatinine kinase, negative ANA panel, normal creatine kinase, and normal INR. Lab abnormalities were most consistent with an irAE with Atezolizumab-induced hepatitis. Patient was discharged with prednisone and outpatient follow-up. DISCUSSION: Checkpoint inhibitors are becoming more frequently utilized in metastatic melanoma, Hodgkin’s Lymphoma, and NSCLC. These immunotherapies are associated with unique irAE, which are different from conventional cytotoxic therapy side-effects. Although Atezolizumab-induced hepatotoxicity is approximately 1%, irAE should be among the differential diagnosis for transaminitis in selected patients.