Cilta-cel, a BCMA-targeting CAR-T therapy for patients with multiple myeloma.

INTRODUCTION: Ciltacabtagene autoleucel (cilta-cel), a BCMA-targeting CAR-T therapy, is approved in the United States and Europe for patients with relapsed/refractory multiple myeloma (RRMM) and ≥1 prior line of therapy (LOT), including a proteasome inhibitor and an immunomodulatory drug, and are lenalidomide refractory. AREAS COVERED: We examine recent long-term data in heavily pretreated RRMM (LEGEND-2, CARTITUDE-1) and earlier LOTs (CARTITUDE-4) compared with standard therapy and discuss the rationale for investigating cilta-cel as frontline therapy for transplant-eligible and transplant-ineligible patients (CARTITUDE-5, CARTITUDE-6). EXPERT OPINION: CAR-T therapies can improve outcomes for patients with MM across different LOTs. CARTITUDE-1 and CARTITUDE-4 have set a new bar for efficacy, with median PFS of 34.9 months in heavily pretreated patients (CARTITUDE-1) and a 74% relative risk reduction for progression/death versus standard care in patients with 1-3 prior LOTs (CARTITUDE-4), with manageable safety. Response rates were consistent between the two studies: 98% in CARTITUDE-1 and approaching 100% for infused patients in CARTITUDE-4. Cilta-cel could be a key treatment choice for patients with RRMM after first LOT. Clinical trials investigating frontline cilta-cel therapy will provide valuable insights into optimizing treatment pathways with the aim to potentially cure MM.

Cilta-cel or Standard Care in Lenalidomide-Refractory Multiple Myeloma.

BACKGROUND: Ciltacabtagene autoleucel (cilta-cel), a B-cell maturation antigen (BCMA)-directed CAR T-cell therapy, is effective in heavily pretreated patients with relapsed or refractory multiple myeloma. We investigated cilta-cel in earlier treatment lines in patients with lenalidomide-refractory disease. METHODS: In this phase 3, randomized, open-label trial, we assigned patients with lenalidomide-refractory multiple myeloma to receive cilta-cel or the physician's choice of effective standard care. All the patients had received one to three previous lines of treatment. The primary outcome was progression-free survival. RESULTS: A total of 419 patients underwent randomization (208 to receive cilta-cel and 211 to receive standard care). At a median follow-up of 15.9 months (range, 0.1 to 27.3), the median progression-free survival was not reached in the cilta-cel group and was 11.8 months in the standard-care group (hazard ratio, 0.26; 95% confidence interval [CI], 0.18 to 0.38; P<0.001). Progression-free survival at 12 months was 75.9% (95% CI, 69.4 to 81.1) in the cilta-cel group and 48.6% (95% CI, 41.5 to 55.3) in the standard-care group. More patients in the cilta-cel group than in the standard-care group had an overall response (84.6% vs. 67.3%), a complete response or better (73.1% vs. 21.8%), and an absence of minimal residual disease (60.6% vs. 15.6%). Death from any cause was reported in 39 patients and 46 patients, respectively (hazard ratio, 0.78; 95% CI, 0.5 to 1.2). Most patients reported grade 3 or 4 adverse events during treatment. Among the 176 patients who received cilta-cel in the as-treated population, 134 (76.1%) had cytokine release syndrome (grade 3 or 4, 1.1%; no grade 5), 8 (4.5%) had immune effector cell-associated neurotoxicity syndrome (all grade 1 or 2), 1 had movement and neurocognitive symptoms (grade 1), 16 (9.1%) had cranial nerve palsy (grade 2, 8.0%; grade 3, 1.1%), and 5 (2.8%) had CAR-T-related peripheral neuropathy (grade 1 or 2, 2.3%; grade 3, 0.6%). CONCLUSIONS: A single cilta-cel infusion resulted in a lower risk of disease progression or death than standard care in lenalidomide-refractory patients with multiple myeloma who had received one to three previous therapies. (Funded by Janssen and Legend Biotech; CARTITUDE-4 ClinicalTrials.gov number, NCT04181827.).

BCMA CAR-T induces complete and durable remission in refractory plasmablastic lymphoma.

Plasmablastic lymphoma (PBL) is a rare subtype of aggressive large B-cell lymphoma, with a dismal prognosis despite aggressive therapies. New approaches are needed for those with refractory disease. PBL expresses antigens similar to multiple myeloma (MM), including B-cell maturation antigen (BCMA). Chimeric antigen receptor T-cell (CAR-T) therapy directed against BCMA has shown efficacy for the treatment of heavily pretreated MM with low rates of grades 3 and 4 cytokine release syndrome (CRS) and immune effector cell-associated neurotoxicity syndrome (ICANS) in a phase Ib/II trial (A Study of JNJ-68284528, a CAR-T Directed Against BCMA in Participants With Relapsed or Refractory Multiple Myeloma (CARTITUDE-1), NCT03548207). However, data for the use of BCMA CAR-T for treating PBL are lacking.We report a challenging case of multiple refractory PBL that emerged from B-cell acute lymphoblastic leukemia in an adolescent who failed to respond to an allogeneic hematopoietic cell transplant. The patient developed rapidly advancing disease despite withdrawal of immunosuppression, treatment with etoposide, ibrutinib, and daratumumab, prompting consideration of BCMA CAR-T (under emergency investigational new drug (eIND)). The patient achieved a complete remission (CR), without recurrent acute graft versus host disease (GVHD), CRS or ICANS after BCMA CAR-T therapy. BCMA CAR-T expansion was detected in vivo, peaking on day 15. The patient remains in CR for more than a year post CAR-T therapy, supporting consideration of immunotherapy for future patients with refractory PBL, a disease with few treatment options.

Continuous induction with lenalidomide/dexamethasone versus autologous stem cell transplantation in newly diagnosed multiple myeloma: a case for response-adapted approach.

Although upfront autologous stem cell transplantation (ASCT) generally improves progression-free survival (PFS) in newly diagnosed multiple myeloma (NDMM), the overall survival (OS) benefit and optimal timing of ASCT are not well established. Patients with early response may be able to safely continue induction and avoid ASCT without compromised outcomes. We report an extended follow-up analysis of a phase 2 trial that randomized transplant-eligible patients with NDMM who responded to induction (50/65 patients) to continued induction or ASCT; median follow-up was 8.0 years. Patients had similar 8-year PFS (55% vs. 43%), 8-year OS (83% vs. 72%), and rates of at least very good partial response (72% vs. 84%) whether continuing induction of lenalidomide and dexamethasone (Ld arm) or receiving ASCT (Ld + ASCT arm) (p = 0.5). Notably, over 50% of patients receiving continuous Ld had PFS of 5-10 years. These results suggest the need for prospective trials incorporating response-adapted therapeutic approaches to NDMM.STATEMENT OF PRIOR PRESENTATIONPresented in abstract form (interim analysis) at the 56th annual meeting of the American Society of Hematology (San Francisco, CA, 6 December 2014) and at the 57th annual meeting of the American Society of Hematology (Orlando, FL, 3 December 2015).

Incidence and management of CAR-T neurotoxicity in patients with multiple myeloma treated with ciltacabtagene autoleucel in CARTITUDE studies.

Chimeric antigen receptor (CAR) T-cell therapies are highly effective for multiple myeloma (MM) but their impressive efficacy is associated with treatment-related neurotoxicities in some patients. In CARTITUDE-1, 5% of patients with MM reported movement and neurocognitive treatment-emergent adverse events (MNTs) with ciltacabtagene autoleucel (cilta-cel), a B-cell maturation antigen-targeted CAR T-cell therapy. We assessed the associated factors for MNTs in CARTITUDE-1. Based on common features, patients who experienced MNTs were characterized by the presence of a combination of at least two variables: high tumor burden, grade ≥2 cytokine release syndrome (CRS) or any grade immune effector cell-associated neurotoxicity syndrome (ICANS) after cilta-cel infusion, and high CAR T-cell expansion/persistence. Strategies were implemented across the cilta-cel development program to monitor and manage patients with MNTs, including enhanced bridging therapy to reduce baseline tumor burden, early aggressive treatment of CRS and ICANS, handwriting assessments for early symptom detection, and extended monitoring/reporting time for neurotoxicity beyond 100 days post-infusion. After successful implementation of these strategies, the incidence of MNTs was reduced from 5% to <1% across the cilta-cel program, supporting its favorable benefit-risk profile for treatment of MM.

Stem Cell Mobilization and Autograft Minimal Residual Disease Negativity with Novel Induction Regimens in Multiple Myeloma.

Autologous stem cell transplantation (ASCT) remains the standard of care for transplantation-eligible patients with multiple myeloma (MM). Bortezomib with lenalidomide and dexamethasone (VRD) is the most common triplet regimen for newly diagnosed MM in the United States. Carfilzomib with lenalidomide and dexamethasone (KRD) has shown promising efficacy and may supplant VRD. We compared stem cell yields and autograft minimal residual disease (MRD)-negativity after VRD and KRD induction. Deeper responses (ie, very good partial response or better) were more common with KRD. Precollection bone marrow (BM) cellularity, interval from the end of induction therapy to start of stem cell collection, and method of stem cell mobilization were similar for the 2 cohorts. Days to complete collection was greater with KRD (2.2 days, versus 1.81 days with VRD), which more often required ≥3 days of apheresis. Precollection viable CD34+ cell content was greater with VRD, as was collection yield (11.11 × 106, versus 9.19 × 106 with KRD). Collection failure (defined as <2 × 106 CD34+ cells/kg) was more frequent with KRD (5.4% versus .7% with VRD). The difference in stem cell yield between VRD and KRD is associated with the degree of lenalidomide exposure. Age ≥70 years predicted poorer collection for both cohorts. Stem cell autograft purity/MRD-negativity was higher with KRD (81.4%, versus 57.1% with VRD). For both cohorts, MRD-negativity was attained in a larger fraction of autografts than in precollection BM. For patients proceeding to ASCT, the time to neutrophil/platelet engraftment was comparable in the 2 study arms. In summary, our data demonstrate that KRD induces deeper clinical responses and greater autograft purity than VRD without compromising stem cell yield or post-transplantation engraftment kinetics.

A dose-finding Phase 2 study of single agent isatuximab (anti-CD38 mAb) in relapsed/refractory multiple myeloma.

A Phase 2 dose-finding study evaluated isatuximab, an anti-CD38 monoclonal antibody, in relapsed/refractory multiple myeloma (RRMM; NCT01084252). Patients with ≥3 prior lines or refractory to both immunomodulatory drugs and proteasome inhibitors (dual refractory) were randomized to isatuximab 3 mg/kg every 2 weeks (Q2W), 10 mg/kg Q2W(2 cycles)/Q4W, or 10 mg/kg Q2W. A fourth arm evaluated 20 mg/kg QW(1 cycle)/Q2W. Patients (N = 97) had a median (range) age of 62 years (38-85), 5 (2-14) prior therapy lines, and 85% were double refractory. The overall response rate (ORR) was 4.3, 20.0, 29.2, and 24.0% with isatuximab 3 mg/kg Q2W, 10 mg/kg Q2W/Q4W, 10 mg/kg Q2W, and 20 mg/kg QW/Q2W, respectively. At doses ≥10 mg/kg, median progression-free survival and overall survival were 4.6 and 18.7 months, respectively, and the ORR was 40.9% (9/22) in patients with high-risk cytogenetics. CD38 receptor density was similar in responders and non-responders. The most common non-hematologic adverse events (typically grade ≤2) were nausea (34.0%), fatigue (32.0%), and upper respiratory tract infections (28.9%). Infusion reactions (typically with first infusion and grade ≤2) occurred in 51.5% of patients. In conclusion, isatuximab is active and generally well tolerated in heavily pretreated RRMM, with greatest efficacy at doses ≥10 mg/kg.

"Please Keep Mom Alive One More Day"-Clashing Directives of a Dying Patient and Her Surrogate.

All medical care providers are legally and ethically bound to respect their patients' wishes. However, as patients lose decision-making capacity and approach end of life, their families or surrogates, who are confronted with grief, fear, self-doubt, and/or uncertainty, may ask physicians to provide treatment that contradicts the patients' previously stated wishes. Our work discusses the legal and ethical issues surrounding such requests and provides guidance for clinicians to ethically and compassionately respond-without compromising their professional and moral obligations to their patients.

Pilot Study of Bortezomib and Dexamethasone Pre- and Post-Risk-Adapted Autologous Stem Cell Transplantation in AL Amyloidosis.

Treatment for AL amyloidosis aims to eradicate clonal plasma cells, thereby disrupting the amyloid deposition causing organ damage. Risk-adapted high-dose melphalan plus autologous stem cell transplantation (RA-ASCT) is an effective therapy. We conducted a prospective pilot analysis of a comprehensive approach using bortezomib and dexamethasone (BD) before and after RA-ASCT in 19 patients. BD induction (up to 3 cycles of bortezomib 1.3 mg/m2 i.v. and dexamethasone 40 mg orally [p.o.] or i.v. on days 1, 4, 8, and 11) was followed by RA-ASCT and then BD consolidation (6 cycles of bortezomib 1.3 mg/m2i.v. and dexamethasone 20 mg p.o. or i.v. weekly for 4 weeks, every 12 weeks). The overall hematologic response rate (partial response or better) was 95%, including 37% minimal residual disease negative [MRD(-)] complete response (CR) by flow cytometry (sensitivity up to 1/106 cells). At 2 years, progression-free survival (PFS) and overall survival were 68% (95% confidence interval [CI], 50% to 93%) and 84% (95% CI, 69% to 99%), respectively, with median duration of follow-up in survivors of 61 months (range, 42 to 84 months). In a landmark analysis, patients achieving MRD(-) CR had superior PFS (P= .008). This approach is safe and yields deep and durable remissions promoting organ recovery. Each treatment phase deepened the response. Future aims include improving the efficacy and toxicity of each phase.

Belantamab mafodotin for relapsed or refractory multiple myeloma (DREAMM-2): a two-arm, randomised, open-label, phase 2 study.

BACKGROUND: Belantamab mafodotin (GSK2857916), an immunoconjugate targeting B-cell maturation antigen, showed single-agent activity in the phase 1 DREAMM-1 study in heavily pre-treated patients with relapsed or refractory multiple myeloma. We further investigated the safety and activity of belantamab mafodotin in the DREAMM-2 study. METHODS: DREAMM-2 is an open-label, two-arm, phase 2 study done at 58 multiple myeloma specialty centres in eight countries. Patients (aged ≥18 years) with relapsed or refractory multiple myeloma with disease progression after three or more lines of therapy and who were refractory to immunomodulatory drugs and proteasome inhibitors, and refractory or intolerant (or both) to an anti-CD38 monoclonal antibody with an Eastern Cooperative Oncology Group performance status of 0-2 were recruited, centrally randomly assigned (1:1) with permuted blocks (block size 4), and stratified by previous lines of therapy (≤4 vs >4) and cytogenetic features to receive 2·5 mg/kg or 3·4 mg/kg belantamab mafodotin via intravenous infusion every 3 weeks on day 1 of each cycle until disease progression or unacceptable toxicity. The intention-to-treat population comprised all randomised patients, regardless of treatment administration. The safety population comprised all patients who received at least one dose of belantamab mafodotin. The primary outcome was the proportion of randomly assigned patients in the intention-to-treat population who achieved an overall response, as assessed by an independent review committee. This study is registered with ClinicalTrials.gov, NCT03525678, and is ongoing. FINDINGS: Between June 18, 2018, and Jan 2, 2019, 293 patients were screened and 196 were included in the intention-to-treat population (97 in the 2·5 mg/kg cohort and 99 in the 3·4 mg/kg cohort). As of June 21, 2019 (the primary analysis data cutoff date), 30 (31%; 97·5% CI 20·8-42·6) of 97 patients in the 2·5 mg/kg cohort and 34 (34%; 23·9-46·0) of 99 patients in the 3·4 mg/kg cohort achieved an overall response. The most common grade 3-4 adverse events in the safety population were keratopathy (in 26 [27%] of 95 patients in the 2·5 mg/kg cohort and 21 [21%] of 99 patients in the 3·4 mg/kg cohort), thrombocytopenia (19 [20%] and 33 [33%]), and anaemia (19 [20%] and 25 [25%]); 38 (40%) of 95 patients in the 2·5 mg/kg cohort and 47 (47%) of 99 in the 3·4 mg/kg cohort reported serious adverse events. Two deaths were potentially treatment related (one case of sepsis in the 2·5 mg/kg cohort and one case of haemophagocytic lymphohistiocytosis in the 3·4 mg/kg cohort). INTERPRETATION: Single-agent belantamab mafodotin shows anti-myeloma activity with a manageable safety profile in patients with relapsed or refractory multiple myeloma. FUNDING: GlaxoSmithKline.

Antibody-drug conjugate, GSK2857916, in relapsed/refractory multiple myeloma: an update on safety and efficacy from dose expansion phase I study.

Interim analyses of a phase I study with GSK2857916, an antibody-drug conjugate against B cell maturation antigen, have previously reported a 60% overall response and 7.9 months progression-free survival in relapsed/refractory multiple myeloma (MM). We provide updated safety and efficacy results of the BMA117159 trial following an additional 14 months' follow-up. This open-label, first-in-human, phase I study was conducted at nine centres in the USA, Canada and the UK, and included adults with MM and progressive disease after stem cell transplantation, alkylators, proteasome inhibitors, and immunomodulators. In part 1, the recommended dose of 3.4 mg/kg was identified; in part 2, patients received GSK2857916 3.4 mg/kg once every 3 weeks. Selected part 2 safety/tolerability and efficacy endpoints are reported. Twenty-one (60.0%; 95% confidence interval (CI) 42.1-76.1) of 35 patients achieved partial response or better, including two stringent complete responses and three complete responses. The median progression-free survival was 12 months and median duration of response was 14.3 months. Thrombocytopenia and corneal events were commonly reported; no new safety signals were identified. GSK2857916 was well tolerated and demonstrated a rapid, deep and durable response in heavily pre-treated patients with relapsed/refractory MM, consolidating the interim analyses conclusions that GSK2857916 is a promising treatment for these patients.

Autologous Lymphocyte Infusion Supports Tumor Antigen Vaccine-Induced Immunity in Autologous Stem Cell Transplant for Multiple Myeloma.

Autologous stem cell transplant (autoSCT), the standard consolidation therapy for multiple myeloma, improves disease-free survival, but is not curative. This could be an ideal setting for immunologic therapy. However, the immune milieu is impaired after autoSCT. We hypothesized that autologous lymphocyte infusion would restore immune competence, allowing immunotherapies such as cancer vaccines to elicit tumor antigen-specific immunity in the setting of autoSCT. In this pilot study (NCT01380145), we investigated safety, immunologic, and clinical outcomes of autologous lymphocyte infusion combined with peri-autoSCT immunotherapy with recombinant MAGE-A3 (a multiple myeloma-associated antigen) and adjuvant. Thirteen patients with multiple myeloma undergoing autoSCT were enrolled. Autologous lymphocyte infusion and MAGE vaccination were well tolerated. Combination immunotherapy resulted in high-titer humoral immunity and robust, antigen-specific CD4+ T-cell responses in all subjects, and the responses persisted at least one year post-autoSCT. CD4+ T cells were polyfunctional and Th1-biased. CD8+ T-cell responses were elicited in 3 of 13 subjects. These cells recognized naturally processed MAGE-A3 antigen. Median progression-free survival was 27 months, and median overall survival was not reached, suggesting no differences from standard-of-care. In 4 of 8 subjects tested, MAGE-A protein expression was not detected by IHC in multiple myeloma cells at relapse, suggesting therapy-induced immunologic selection against antigen-expressing clones. These results demonstrated that autologous lymphocyte infusion augmentation of autoSCT confers a favorable milieu for immunotherapies such as tumor vaccines. This strategy does not require ex vivo manipulation of autologous lymphocyte products and is an applicable platform for further investigation into combination immunotherapies to treat multiple myeloma.

Targeting B-cell maturation antigen with GSK2857916 antibody-drug conjugate in relapsed or refractory multiple myeloma (BMA117159): a dose escalation and expansion phase 1 trial.

BACKGROUND: B-cell maturation antigen (BCMA) is a cell-surface receptor of the tumour necrosis superfamily required for plasma cell survival. BMCA is universally detected on patient-derived myeloma cells and has emerged as a selective antigen to be targeted by novel treatments in multiple myeloma. We assessed the safety, tolerability, and preliminary clinical activity of GSK2857916, a novel anti-BCMA antibody conjugated to microtubule-disrupting agent monomethyl auristatin F, in patients with relapsed and refractory multiple myeloma. METHODS: We did an international, multicentre, open-label, first-in-human phase 1 study with dose escalation (part 1) and dose expansion (part 2) phases, at nine centres in the USA, Canada, and the UK. Adults with histologically or cytologically confirmed multiple myeloma, Eastern Cooperative Oncology Group performance status 0 or 1, and progressive disease after stem cell transplantation, alkylators, proteasome inhibitors, and immunomodulators were recruited for this study. In part 1, patients received GSK2857916 (0·03-4·60 mg/kg) through 1 h intravenous infusions once every 3 weeks. In part 2, patients received the selected recommended phase 2 dose of GSK2857916 (3·40 mg/kg) once every 3 weeks. Primary endpoints were maximum tolerated dose and recommended phase 2 dose. Secondary endpoints for part 2 included preliminary anti-cancer clinical activity. All patients who received one or more doses were included in this prespecified administrative interim analysis (data cutoff date June 26, 2017), which was done for internal purposes. This study is registered with ClinicalTrials.gov, number NCT02064387, and is ongoing, but closed for recruitment. FINDINGS: Between July 29, 2014, and Feb 21, 2017, we treated 73 patients: 38 patients in the dose-escalation part 1 and 35 patients in the dose-expansion part 2. There were no dose-limiting toxicities and no maximum tolerated dose was identified in part 1. On the basis of safety and clinical activity, we selected 3·40 mg/kg as the recommended phase 2 dose. Corneal events were common (20 [53%] of 38 patients in part 1 and 22 [63%] of 35 in part 2); most (18 [47%] in part 1 and 19 [54%] in part 2) were grade 1 or 2 and resulted in two treatment discontinuations in part 1 and no discontinuations in part 2. The most common grade 3 or 4 events were thrombocytopenia (13 [34%] of 38 patients in part 1 and 12 [34%] of 35 in part 2) and anaemia (6 [16%] in part 1 and 5 [14%] in part 2). There were 12 treatment-related serious adverse events and no treatment-related deaths. In part 2, 21 (60·0%; 95% CI 42·1-76·1) of 35 patients achieved an overall response. INTERPRETATION: At the identified recommended phase 2 dose, GSK2857916 was well tolerated and had good clinical activity in heavily pretreated patients, thereby indicating that this might be a promising candidate for the treatment of relapsed or refractory multiple myeloma. FUNDING: GlaxoSmithKline.

Ibrutinib alone or with dexamethasone for relapsed or relapsed and refractory multiple myeloma: phase 2 trial results.

Novel therapies with unique new targets are needed for patients who are relapsed/refractory to current treatments for multiple myeloma. Ibrutinib is a first-in-class, once-daily, oral covalent inhibitor of Bruton tyrosine kinase, which is overexpressed in the myeloma stem cell population. This study examined various doses of ibrutinib ± low-dose dexamethasone in patients who received ≥2 prior lines of therapy, including an immunomodulatory agent. Daily ibrutinib ± weekly dexamethasone 40 mg was assessed in 4 cohorts using a Simon 2-stage design. The primary objective was clinical benefit rate (CBR; ≥minimal response); secondary objectives included safety. Patients (n = 92) received a median of 4 prior regimens. Ibrutinib + dexamethasone produced the highest CBR (28%) in Cohort 4 (840 mg + dexamethasone; n = 43), with median duration of 9·2 months (range, 3·0-14·7). Progression-free survival was 4·6 months (range, 0·4-17·3). Grade 3-4 haematological adverse events included anaemia (16%), thrombocytopenia (11%), and neutropenia (2%); grade 3-4 non-haematological adverse events included pneumonia (7%), syncope (3%) and urinary tract infection (3%). Ibrutinib + dexamethasone produced notable responses in this heavily pre-treated population. The encouraging efficacy, coupled with the favourable safety and tolerability profile of ibrutinib, supports its further evaluation as part of combination treatment.

Treatment of multiple myeloma with monoclonal antibodies and the dilemma of false positive M-spikes in peripheral blood.

OBJECTIVES: To characterize the effect of three humanized IgG κ monoclonal antibodies (daratumumab, isatuximab, and elotuzumab) on the interpretation of results generated by protein electrophoresis, immunofixation, free light chain, and heavy/light chain assays performed on human serum. METHODS: Healthy volunteer serum and serum from multiple myeloma patients were supplemented with clinically relevant concentrations of each of the three monoclonal antibodies. These specimens then underwent analysis via serum protein electrophoresis, immunofixation, serum free light chain quantification, heavy/light chain quantification, total IgG, and total protein. In addition, serum specimens from patients who had undergone treatment with elotuzumab for multiple myeloma underwent similar analysis. RESULTS: Addition of the study drugs to serum from both the healthy donor as well as multiple myeloma patients resulted in a visible and quantifiable M-protein on SPEP and a visible IgGκ band by IFE. Increases were also noted in total IgG, IgGκ, and IgGκ/IgGλ-ratios. Analysis of serum from multiple myeloma patients receiving study drug showed similar findings with an additional IgGκ band and quantifiable M-protein with similar migration patterns in specimens drawn after administration. CONCLUSION: The treatment of multiple myeloma patients with monoclonal antibodies results in a visible and quantifiable M-protein that has the potential to falsely indicate poor response to therapy.