Use of free light chain analysis in the diagnosis, prognosis and therapy of multiple myeloma. Amitabha Mazumder, MD

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1 Use of free light chain analysis in the diagnosis, prognosis and therapy of multiple myeloma Amitabha Mazumder, MD

2 Monoclonal Gammopathies Multiple Myeloma 18% Light Chain Dep Ds < 1% AL Amyloidosis 9% Lymphoproliferative Ds 3% Plasmacytoma 2% Macroglobulinemia 2% Other 1% Smoldering myeloma 3% N = 29,528 Mayo Clinic Database MGUS 61% Katzmann JA. Clin Lab News. June Katzmann et al. Clin Chem. 2005;51:

3 Diagnosis Prognosis Monitoring Response to Treatment

4 Query Myeloma: diagnostic workup SPEP Immunofixation electrophoresis UPEP or uife on 24-h urine Serum free light chain assays Serum panels

5 Diagnosis of multiple myeloma: 1. Monoclonal plasma cells

6 Sensitivity of SPEP Myeloma 1 LCMM 2 AL Amy 3 LCDD 4 NSMM SPEP alone ~ 80% 45% 50% 25% 0% 1 Katzmann et al. Mayo Clin Proc Bradwell et al. Lancet Lachmann et al. Br J Haematol Lin et al. JASN

7 Serum Free Light Chain Assays: Polyclonal Ab to sequestered Light Chain epitopes Exposed surface Sequestered surface Kappa Exposed surface Heavy chain Antibody target Light chain Lambda

8 Principles of the sflc assays Polyclonal antibodies against epitopes in the constant region of k and l light chains which are sequestered in intact immunoglobulin Measures only free κ and λ Recognizes both monomeric and polymeric structures Far more sensitive than SPEP or IFE Nephelometric or turbidometric technique Assay has been adapted for use on most automated chemistry analyzers

9 sflc assays measure only free light chains Assay Detects bound LC? Detects free LC? Kappa range (mg/l) Lambda range (mg/l) Total κ/λ Yes Yes sflc No Yes

10 FLC concentrations in sera containing monoclonal FLCs that were difficult to detect by IFE.

11 Sensitivity of assays for Light Chains 1000 Light chain concentration (mg/l) SPEP Total κ & λ CZE Normal range in serum Normal range in urine sife sflc UPEP uife Adapted from Bradwell et al. Serum Free Light Chain Analysis. 3 rd ed The Binding Site, Ltd.

12 LCDD showing normal SPE (scanning densitometry) and IFE, but sflcs were highly abnormal (κ 294mg/L: λ 71.6mg/L and κ/λ ratio: 4.1). T: Protein stain. (Courtesy of L Guis).

13 Concentrations of sflc, total IgG and monoclonal IgG κ after high-dose melphalan. (Courtesy of G Pratt).

14 Serum Free Light Chains: normal ranges κ 95% reference interval: mg/l λ 95% reference interval: mg/l κ/λ ratio 95% reference interval: Normal range: Median 0.59 Katzmann et al. Clin Chem. 2002

15 Light Chain Metabolism Production Kappa : Lambda 60 : 40 Kappa Lambda Clearance Final Serum Concentration Kappa : Lambda ~ 1 : 2 median = 0.6

16 Reabsorption of Light Chains in PCT decreases concentration in urine 500 mg light chains produced/day 5-10 mg light chains excreted/day

17 Establishing renal reference range for FLC in CKD Hutchison et al. cjasn kappa lambda Hutchison et al, BMC Nephrol established renal reference range κ:λ in patients with renal failure and no other evidence of monoclonal protein

18 Serum and urine FLCs during the development of LCMM 50,000 50,000 Serum FLC (mg/l) 5, Serum FLC Urine FLC Overflow proteinuria Renal impairment Normal range: serum urine 5,000 2,000 1, Urine FLC (mg/l) Time (months)

19 Comparison of sflcs and UBJP Urine Lambda BJP (g/24hr) HDC ASCT Time (months) Serum Lambda FLC (mg/l) Patient 1 Urine Kappa BJP (g/24hr) Thalidomide Time (months) Serum Kappa FLC (mg/l) Patient 2 Urine Kappa BJP (g/24hr) Severe osteolytic lesions Serum Kappa FLC (mg/l) Urine Kappa BJP (g/24hr) Time (months) Time (months) Patient 3 Patient HDC ASCT Serum Kappa FLC (mg/l) sflc 24 hr urine BJP excretion Alyanakian Am J. Hematol. 2004; 75:

20 Can the sflc assay replace urine tests? The authors conclude: As no significant pathology would have been missed by replacing urine Bence Jones proteins with serum FLC, we no longer require a urine sample as part of the initial screen. Hill et al. Clin Chem. 2006

21 Light Chain Myeloma Serum lambda, mg/l Sensitivity of IFE Sensitivity of SPEP N = 224 with LCMM Normal sera Kappa LCMM Lambda LCMM Renal impairment Serum kappa, mg/l Bradwell et al. Lancet. 2003; 361:

22 Nonsecretory Myeloma Less than 3% of all patients with myeloma No paraprotein detectable on SPEP, UPEP 85% of NSMM have cytoplasmic M-protein in plasma cells by IHC 68% of NSMM detectable by sflc testing Patients now been reclassified as hyposecretory or oligosecretory Drayson et al. Blood, 2001

23 NSMM

24 Approximate diagnostic sensitivity of tests for monoclonal gammopathies. (See relevant clinical chapters for details).

25 International guidelines for diagnosis of Multiple Myeloma 1. M-protein in the serum and/or urine* by SPEP, 24h UPEP, IFE, or an abnormal serum free light chain ratio 2. 10% monoclonal plasma cells in the bone marrow and/or presence of a biopsy-proven plasmacytoma 3. Myeloma-related organ dysfunction (CRAB) Hypercalcemia Renal insufficiency Anemia Bone lesions (osteolytic lesions) or osteoporosis *If none identified, need 30% PC in BM or bx proven plasmacytoma Durie et al. Leukemia

27 Prevalence and risk of progression in MGUS Among 21,463 residents of Olmsted County, MN (77% of residents > 50 years old), MGUS was identified in 3.2 % of persons 50 years of age or older 5.3 % of persons 70 years of age or older 1 Prevalence of MGUS: 3-fold higher in African Americans 2 Rate of progression to multiple myeloma or a related malignant condition is 1% per year 3 Rate does not change with time indefinite follow-up Risk assessment strategies desirable 1 Kyle et al. N Engl J Med Landgren et al. Blood Kyle et al. N Engl J Med. 2002

28 MGUS patients with abnormal FLC ratio progress to MM more frequently 1/3 of pts with MGUS had abnormal sflc ratio at baseline n = 1148 p < Abnormal free light chain ratio Normal free light chain ratio Rajkumar et al. Blood. 2005

29 MGUS: risk stratification Low Risk M-spike < 1.5 g/dl IgG subtype Normal FLC ratio Low-intermediate Any 1 factor abnormal High-intermediate Any 2 factors abnormal High All 3 factors abnormal No. of Patients Relative Risk (95% CI) Absolute Risk at 20 yrs % % % % N = 1148 Free light chain testing not FDA cleared for this indication Rajkumar et al. Blood

30 Percentages in risk groups 58% Risk of Progression: 3 risk factors 37% Risk of Progression: 2 risk factors 20% 5% 39% 5% Risk of Progression: No risk factors 37% 21% Risk of Progression: 1 risk factor Rajkumar et al. Blood. 2005

31 Kaplan-Meier plots for time to progresssion to multiple myeloma in 116 patients with solitary bone plasmacytoma and normal (62) or abnormal (54) sflc ratios.* (Courtesy of D Dingli and American Society of Hematology).

32 Using sflc to assess risk of progression in SMM Dispenzieri et al (Blood 2008) examined risk factors in 273 SMM patients M-protein > 3g/dl and/or BMPC > 10% no end organ involvement (CRAB) Minimum potential follow up 10 years (median 12.4 years) 68% kappa; 32% lambda (3% biclonal) 245/273 patients had abnormal FLC ratio median ratio involved:uninvolved light chain: 11.2 median concentration involved light chain 74 mg/l

33 SMM patients with abnormal FLC ratio progress more rapidly Dispezieri et al. Blood 2008

34 A. Disease-specific survival of MM patients according to baseline sflc κ/λratios.* B. Disease-specific survival of MM patients according to abnormalities of baseline sflc κ/λ ratios, serum albumin or β2-microglobulin as used in the International Staging System. (Courtesy of M-C Kyrtsonis).

35 Normalization of sflcs prior to PBSCT in MM is a good indication of subsequent complete response after treatment. (Courtesy of G Tricot).

37 Monitoring response to Rx Immunoglobulin Half Life Isotype Half Life IgG days IgA 6 days IgM 6 8 days free Kappa 2 4 hours free Lambda 3 6 hours Total Kappa or Lambda: half life dependent on Ig isotype

38 Responsiveness of FLC measurements in a patient with IgGκ myeloma κ/λ ratio V V V V V V Normal κ/λ κ/λ ratio IgG Time, days Normal IgG Total IgG, g/l

39 Intact Ig MM: Monitoring treatment response Serum Lambda FLC (mg/l) Chemotherapy ABCM Lambda FLC IgG Lambda NR λ NR IgG (g/l) Time from presentation (days)

40 Patient with Kappa Myeloma monitored weekly using FLC Assays: response to Rx Radiation Thalidomide Dex Bortezomib 1000 Kappa, mg/l Normal Range Kappa 1

41 Serum Free Light Chain assays predict CR earlier than SPEP Stage II/III MM, N = 42 at Memorial Sloan Kettering 1 Dox/Dex 2 3 cycles thal/dex 2 cycles Serum free light chain assays performed q cycle RR 91% 7 CR, 9 ncr, 22 PR Normalization of serum free light chain ratio after 1 or 2 cycles was significantly associated with subsequent CR or ncr (p = 0.003) May allow addition of alternative treatment at an early stage if free light chain ratio remains abnormal Univ of Arkansas monitoring q cycle 2 1 Hassoun et al. Br J Haematol van Rhee et al. Blood

42 sflc can identify residual disease 1000 Serum λ FLC (mg/l) Normal sera IFE negative MM: Normal κ/λ Abnormal κ/λ Serum κ FLC (mg/l)

43 Serum FLCs and IFE during relapse of patients with MM. (Courtesy of N Kroger).

44 Early tumor recurrence identified from rising λ sflc levels while IgGλ continued to fall. Tumor relapse occurred before IgGλ had stabilized.

45 Extramedullary relapse and Light Chain escape 3 patients with IIgMM (2 IgAk, 1 IgGk) Ig levels correlated with disease activity until relapse No IgA/IgG at relapse Marked FLC appearance at relapse. Multiple extramedullary sites of disease at relapse 1. 4 cycles CY/Ida/Dex 2. Thalidomide begun 3. Thalidomide stopped 4. Relapse Patients were negative for light chains by upe and uife at diagnosis of throughout follow up Dawson et al. Haematologica 2007

46 Light Chain Escape Kuhenmund et al (J. Cancer Res., 2008) 10 MM (of 407, 2.46%) patients with apparently stable disease developed severe organ failure Patients treated with SCT and/or thalidomide LCE occurred months after diagnosis Median 6 cycles therapy before LCE occurred

47 International Uniform Response Criteria in Myeloma Stringent CR Normal free light chain ratio Absence of clonal PC in BM by IHC or IF Complete response (CR) Serum and urine IFE negative BM bx 5% PC Disappearance of soft tissue plasmacytoma Normalization of FLC ratio in pts not measurable using above 2 methods VGPR IF positive but SPEP negative or 90% in serum M protein, and urine M protein < 100 mg/24 h Partial response (PR) in serum M protein by 50% and in urine M protein by 90% or to < 200 mg/24 h and in plasmacytoma size by 50% (if present) Non secretory MM: 50% in BM PC 50% in difference between involved and uninvolved [sflc] Stable disease: not meeting criteria for CR, scr, PR or PD Durie et al. Leukemia. 2006

48 Serum Free Light Chain Assays Diagnosis: More sensitive than SPEP or IFE Enhanced diagnostic capability when used in conjuction with either SPE or IFE When combined with SPEP, obviates need for BJP testing Prognosis: Risk stratification models for MGUS, SMM, newly diagnosed MM Monitoring response to therapy Shorter half-life of FLC provides more rapid response indicator than monitoring intact Ig Abnormal ratio can detect underlying disease when SPE or IFE normalize

49 Diagram illustrating the mechanism of antigen excess. The light scattering signal falls in antigen excess because of smaller immune complexes.

50 Limitations of serum free light analysis 1). sflc assays will not measure intact mono Ig 2). Oligoclonal banding, biclonal and polyclonal sflc 3). Urine FLC immunoassays may yield higher values 4). Nonlinearity of sflc on dilution (polymerization or fragments, nonspecific assay interference lipid, hgb) 5). Ratio may be 0 or infinite mathematically 6). Need for international standards and materials

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