#2108 Secondary amyloidosis in a cancer patient on pembrolizumab—an unusual finding
Authors: Biswas Anindya , Aggarwal Neeru , Goswamy Vikas 
Published: May 2024

Abstract

Background and Aims
With the widening horizon of ICPIs in the management of oncological disorders, we require to remain vigilant of the possible iRAEs. We present a case report of secondary amyloidosis in at metastatic non-small cell lung carcinoma (NSCLC) patient treated with Pembrolizumab. We aim to describe the clinic-biological & histopathological characteristics of ICPI-related kidney injury which may be beyond interstitial nephritis & its response to treatment & the role of kidney biopsy to define ICPI-related kidney injury. Treatment is challenging due to a paucity of relevant data, implicating further studies. Treatment with colchicine and steroids, tocilizumab in the setting of elevated interleukin-6 (IL6) levels have been reported in case series; unfortunately no appreciable renal benefit were noted.

Method
77 year male, diabetic & hypertensive on regular medication for &gt;15 yr, reformed smoker (≈50 pack-years of cigarette) diagnosed with NSCLC (EGFR–wild type, PDL1–70%), received Pembrolizumab (13 cycles) & Paclitaxel + Carboplatin & was in remission. Follow up PET showed partial response—new lesions in brain. Gemcitabine added to the treatment & had received 2 cycles, till hospitalization with febrile episode, decreased oral intake & progressive edema. Clinical evaluation was non-contributory. Hematology & biochemical evaluation (Table 1) showed raised serum creatinine 1.1 mg/dL (baseline 1 mg/dL), urinalysis—2+ protein, quantification showed 2.9295 g/24 h → 6.38 g/24 h (baseline uPCR-0.19 g/g). Abdominal ultrasound & ECHO finding were not conclusive. Fundoscopy showed no evidence of proliferative diabetic or hypertensive retinopathy.

Results
Kidney Biopsy (Figure) was done. LM showed, few of 8 gloms with mild segmental mesangial expansion due to amorphous extracellular deposits which was PAS & silver negative but showed congophilia (Fig. A,B,C,D). If negative for albumin, IgG, IgA, C3, C1q & had 1+ granularity in the mesangium on IgM staining & showed no light chain restriction in glomeruli & tubular cast for kappa & lambda. IHC (Fig. E) was positive for serum amyloid associated proteins. EM revealed minimal subendothelial & mesangial expansion due to extracellular material organized into randomly arranged fine fibrils, & no significant foot process effacement, electron dense deposits along the capillary basement membrane or within mesangium, glomerular basement membrane, thereby excluding possibility of light chain deposition disease.

Conclusion
Secondary amyloidosis with ICPI use has uncommonly & with Pembrolizumab rarely been reported. Treatment is challenging due to paucity of literature. Hassan Izzedine et al. in their case series, on Pembrolizumab treated cancer patient [N = 676], showed 12 patients (7 men) (Incidence 1.77%) developed AKI (n = 10) &/or Proteinuria (n = 2), median duration of use 9 months. All (n = 12) underwent renal biopsy, which showed AIN in 4, ATI in 5, MCD in 2. Recovery happened with withdrawal of drug coupled with corticosteroid. Reintroduction resulted in more severe recurrence of AIN in 1 patient only. Lapman et al. reported 1 case of secondary amyloidosis in cancer patients treated with Pembrolizumab. 42yr male Caucasian, had no reported chronic illness, except Asthma. Similarly developed significant proteinuria (Urine Pro 3+) & AKI (Sr. Creat 1.58 mg/dl; Baseline 1.0 mg/dl) after 90 days of Pembrolizumab therapy. Under went 2 Kidney Biopsy–1st Biopsy revealed AA amyloid. AA amyloidosis was attributed to Pembrolizumab as repeat Bx revealed progressive deposits despite remission of malignancy, but his kidney disease progressed, and had to be initiation on maintenance hemodialysis. Stopping Pembrolizumab & corticosteroids led to resolution of proteinuria in our patient too.