MGUS Transformation Into Multiple Myeloma In Patients With Solid Organ Transplantation
Authors: Younes Mohamad A. , Perez Jonathan D , Alirhayim Zaid , Ochoa Cesar , Patel Ruchir , Dabak Vrushali S. 
Published: October 2019

Abstract
The risk of transformation of MGUS to MM is well studied and considered to be around 1%/year. However, this risk is not well defined in patients who undergo solid organ transplantation. A study by Jimenez et al Transplantation,2011 Sep 15;92(5):570-4 found no increased risk of transformation of MGUS to MM, but the sample size of patients who were diagnosed with MGUS prior to transplantation was small (34 patients). In another study by Naina et al Am J Nephrol. 2012;35(4):365-71, 2 out of 17 (11.7%) patients with pre-transplant MGUS and kidney transplant developed smoldering MM. To investigate this topic further, we reviewed the charts of patients who underwent solid organ transplant and who had a pre-transplant diagnosis of MGUS between years 2000 and 2010 and studied the incidence of transformation to MM in these patients. Patients who had MGUS diagnosed after the solid organ transplant were excluded. 57 patients were eligible. The number of patients with different kinds of transplant was as follows: 22 had liver transplant, 31 had kidney transplant, 3 patients had lung transplant, and 1 patient had heart transplant. The mean age was 57.3 years (range 32-76 years). 26.3% were females. The mean follow up was 45.6 months (range 1-156 months). The mean M protein on diagnosis was 0.52 g/dl. 16 patients had pre-transplant bone marrow biopsy with a mean plasma cell percentage of 4% (range 1-9%). 14 patients had normal cytogenetics and 1 patient had Trisomy 11 and another had deletion Y. 29 patients had their serum light chain ratio checked and it was normal in 22 out of 29 patients and abnormal in 7 patients.
None of the 57 patients were diagnosed with MM during the follow up period. 1 patient developed PTLD 5 years post transplant. 14 patients died and 43 patients were still alive at the time of last follow up. Follow up on M protein was available for 35 patients with a mean follow up of 54 months (range 2-144 months) with the following observations: 19 patients (54%) had stable M protein (10 kidney, 8 liver, 1 lung), 6 patients (17%) had increase in M protein by at least 0.1 g/dl (4 kidney and 2 liver), and 10 patients had their M protein decrease or resolve (5 kidney, 4 liver, 1 Heart). Mean time to death was 18.65 months (1- 68.8 months). None of the deaths were related to MM and the causes were as follows: infection (3), GI bleed (1), malignancy (3) being Kaposi sarcoma, HCC and PTLD, liver failure (2), uremia (1), CVA (1), unknown (3). Immunosuppressants included mainly medrol, prograf, cellcept, cyclosporine and rapamune.

Conclusion
MGUS is not a contraindication to solid organ transplant as none of the patient developed MM during the follow up period and deaths were not related to progression of MGUS to MM. As 6 out of 57 patients (10.5%) had increase in M protein despite none being diagnosed with MM, we do suggest continued follow up on these patients at least once a year.

Disclosures:
No relevant conflicts of interest to declare.