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3229 Light Chain Deposition Disease: First Analysis of an International Study in 359 Patients

Program: Oral and Poster Abstracts
Session: 653. Myeloma/Amyloidosis: Therapy, excluding Transplantation: Poster III
Hematology Disease Topics & Pathways:
multiple myeloma, Diseases, Plasma Cell Disorders, Lymphoid Malignancies, Clinically relevant
Monday, December 7, 2020, 7:00 AM-3:30 PM

Paolo Milani, MD, PhD1, Nelson Leung, MD2, Efstathios Kastritis, MD3*, Stefan Schönland, MD4*, Ute Hegenbart, MD5*, Frank Bridoux, MD6*, Florent Joly, MD7*, Sascha A Tuchman, MD8, Victor Jimenez-Zepeda, MD9, Sriram Ravichandran, MBBS, MRCP, FRCPath10*, Holly Lee, MD11, Tamara Berno, MD12*, Giampaolo Merlini, MD13, Giovanni Palladini, MD, PhD14 and Ashutosh D. Wechalekar, MBBS, FRCP, FRCPath, DM15

1Amyloidosis Research and Treatment Center, Department of Molecular Medicine, Foundation IRCCS Policlinico San Matteo, Pavia, Italy
2Mayo Clinic Rochester, Division of Hematology, Rochester, MN
3Department of Clinical Therapeutics, National and Kapodistrian University of Athens, School of Medicine, ATHENS, Greece
4Medical Department V, Amyloidosis Center, Heidelberg University Hospital, Heidelberg, Germany
5Medicine V, University of Heidelberg, Heidelberg, Germany
6CHU Poitiers, Poitiers, FRA
7Department of Nephrology and Renal Transplantation, INSERM CIC 1402, Poitiers University Hospital, POITIERS, France
8University of North Carolina, Chapel Hill, NC
9Tom Baker Cancer Center, Department of Hematology, University of Calgary, Calgary, AB, Canada
10National Amyloidosis Centre, Royal Free Hospital, Leighton Buzzard, ENG, United Kingdom
11Department of Internal Medicine, University of Calgary, Calgary, AB, Canada
12Hematology and Clinical Immunology, Department of Medicine, Padua University School of Medicine, Padova, ITA
13Amyloidosis Research and Treatment Center, Fondazione IRCCS Policlinico San Matteo, and Department of Molecular Medicine, University of Pavia, Pavia, Italy
14Amyloidosis Research and Treatment Center, Fondazione IRCCS Policlinico San Matteo, and Department of Molecular Medicine, University of Pavia, Pavia, PV, Italy
15University College London, Guildford, United Kingdom

Introduction: Light chain deposition disease (LCDD) is a rare complication of monoclonal gammopathies, defined by non-amyloid linear monoclonal light chain (most commonly kappa) deposits in the kidney and other organs. The rarity of LCDD has hampered clinical studies and staging systems and response criteria are lacking. The International Kidney Myeloma Working Group (IKMG) started a clinical data collection from all participating centers in order to define the natural history of LCDD, and to establish prognostic factors and response criteria in a large, international, unselected patient population.

Methods: Eight referral centers have yet participated in the data collection at the data lock of July 31, 2020. Patient inclusion is ongoing and expected accrual is 500 patients. The diagnosis of LCDD had to be biopsy-proven. The patients were diagnosed between 1992 to 2020. Response was assessed 6 months after treatment initiation according to the criteria used in light chain (AL) amyloidosis. Renal survival (RS) was defined as time from diagnosis to dialysis or last follow-up. Patients who died without requiring dialysis were censored at the time of death. The analysis of factors predicting RS was performed in patients whose baseline estimated glomerular filtration rate (eGFR) was >15 mL/min. The cutoffs of baseline variables, as well as the cutoffs measured at the time of response, best predicting RS or OS at 12 months were identified by means of Receiver Operator Characteristics (ROC) analyses. All patients gave written informed consent for their clinical data to be used for research purposes.

Results: Overall, 359 patients have been included in this first analysis. Sixteen (4%) subjects had concomitant cast nephropathy. The main clinical characteristics are reported in the Table. Median overall survival (OS) was 13 years and RS was 12 years (Figure1 A and 1B) and median survival of living patients is 4.5 years. At univariate analysis the only baseline variables predicting RS were proteinuria [best cutoff 2.5 g/24h, HR 2.25 (95%CI 1.13-4.60), P=0.02], and eGFR [best cutoff >30 mL/min, HR 0.50 (95%CI 0.26-0.96) P=0.037], but at multivariate analysis only proteinuria predicted RS [HR 2.17 (95% CI 1.08, 4.33), P=0.027]. At univariate analysis, a higher bone marrow plasma cell infiltrate (best cutoff ≥20%) at diagnosis was associated with a significantly lower OS [HR 1.96 (95% CI 1.23-3.13) P=0.004], as was having end stage renal disease (ESRD) defined as an eGFR <15 mL/min [HR 1.81 (95%CI 1.11-2.92) P=0.015]. We then tested the ability of the hematologic response criteria for AL amyloidosis to discriminate groups with different survival after treatment in a 6 months landmark analysis. Our choice of adopting the amyloidosis response criteria was corroborated by the results of the ROC analysis showing that the difference between involved and uninvolved free light chains (dFLC) cutoff (40 mg/L) used in AL amyloidosis to define very good partial response (VGPR) had 87% sensitivity and 65% specificity in identifying patients who needed dialysis within 12 months. Partial response (PR, 19% requiring dialysis at 3 years) was not associated with a RS benefit over no-response (29% requiring dialysis at 3 years, P=0.511). However, VGPR conferred a significant RS advantage (10% requiring dialysis at 3 years) over PR (P=0.002). No significant difference in RS was seen between complete response (CR, 0% requiring dialysis at 3 years) and VGPR (P=0.178). Thus, achieving VGPR or CR by amyloidosis response criteria [post-treatment dFLC<40 mg/L (VGPR by AL criteria), with or without negative serum and urine immunofixation and normal FLC-ratio (CR by AL criteria)] was adopted as a provisional criterion for hematologic response in LCDD (Figure 1D). LCDD response was also associated with prolonged OS (Figure 1C).

Conclusions: Almost one-third of patients with LCDD are diagnosed when they already have ESRD resulting in shorter OS. The degree of proteinuria and of bone marrow plasma cell infiltration predict RS and OS, respectively. Achievement of post treatment dFLC <40 mg/L or negative serum and urine immunofixation at 6 months is proposed as a provisional criterion for hematologic response, being able to predict both improved RS and OS. Planned expanded recruitment might allow a validation analysis of the results, the analysis of organ response data and the evaluation of different time-points for response assessment.

Disclosures: Milani: Celgene: Other: Travel support; Janssen: Other: Speaker honoraria; Pfizer: Other: Speaker honoraria. Kastritis: Pfizer: Consultancy, Honoraria; Janssen: Consultancy, Honoraria, Research Funding; Takeda: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Genesis Pharma: Consultancy, Honoraria. Schönland: Janssen, Prothena, Takeda: Honoraria, Other: travel support to meetings, Research Funding. Bridoux: Baxter: Consultancy; Janssen: Honoraria; Celgene: Honoraria. Tuchman: Celgene: Honoraria, Research Funding, Speakers Bureau; Oncopeptides: Consultancy; Amgen: Research Funding; Caelum: Honoraria; Sanofi: Honoraria, Research Funding; Janssen: Research Funding; Roche: Research Funding; Karyopharm: Honoraria, Research Funding. Jimenez-Zepeda: Janssen, Celgene, Amgen, Takeda: Honoraria. Palladini: Celgene: Other: Travel support; Jannsen Cilag: Honoraria, Other. Wechalekar: Celgene: Honoraria; Caelum: Other: Advisory; Janssen: Honoraria, Other: Advisory; Takeda: Honoraria, Other: Travel.

*signifies non-member of ASH