Patient-reported outcomes in ZUMA-7, a phase 3 study of axicabtagene ciloleucel in second-line large B-cell lymphoma.

Here, we report the first comparative analysis of patient-reported outcomes (PROs) with chimeric antigen receptor T-cell therapy vs standard-of-care (SOC) therapy in second-line relapsed/refractory large B-cell lymphoma (R/R LBCL) from the pivotal randomized phase 3 ZUMA-7 study of axicabtagene ciloleucel (axi-cel) vs SOC. PRO instruments were administered at baseline, day 50, day 100, day 150, month 9, and every 3 months from randomization until 24 months or an event-free survival event. The quality of life (QoL) analysis set comprised patients with a baseline and ≥1 follow-up PRO completion. Prespecified hypotheses for Quality of Life Questionnaire-Core 30 (QLQ-C30) physical functioning, global health status/QoL, and EQ-5D-5L visual analog scale (VAS) were tested using mixed-effects models with repeated measures. Clinically meaningful changes were defined as 10 points for QLQ-C30 and 7 for EQ-5D-5L VAS. Among 359 patients, 296 (165 axi-cel, 131 SOC) met inclusion criteria for QoL analysis. At day 100, statistically significant and clinically meaningful differences in mean change of scores from baseline were observed favoring axi-cel over SOC for QLQ-C30 global health status/QoL (estimated difference 18.1 [95% confidence interval (CI), 12.3-23.9]), physical functioning (13.1 [95% CI, 8.0-18.2]), and EQ-5D-5L VAS (13.7 [95% CI, 8.5-18.8]; P < .0001 for all). At day 150, scores significantly favored axi-cel vs SOC for global health status/QoL (9.8 [95% CI, 2.6-17.0]; P = .0124) and EQ-5D-5L VAS (11.3 [95% CI, 5.4-17.1]; P = .0004). Axi-cel showed clinically meaningful improvements in QoL over SOC. Superior clinical outcomes and favorable patient experience with axi-cel should help inform treatment choices in second-line R/R LBCL. This trial was registered at www.clinicaltrials.gov as #NCT03391466.

A Randomized Trial of Mesenchymal Stromal Cells for Moderate to Severe Acute Respiratory Distress Syndrome from COVID-19.

Rationale: There are limited therapeutic options for patients with coronavirus disease (COVID-19)-related acute respiratory distress syndrome with inflammation-mediated lung injury. Mesenchymal stromal cells offer promise as immunomodulatory agents. Objectives: Evaluation of efficacy and safety of allogeneic mesenchymal cells in mechanically-ventilated patients with moderate or severe COVID-19-induced respiratory failure. Methods: Patients were randomized to two infusions of 2 million cells/kg or sham infusions, in addition to the standard of care. We hypothesized that cell therapy would be superior to sham control for the primary endpoint of 30-day mortality. The key secondary endpoint was ventilator-free survival within 60 days, accounting for deaths and withdrawals in a ranked analysis. Measurements and Main Results: At the third interim analysis, the data and safety monitoring board recommended that the trial halt enrollment as the prespecified mortality reduction from 40% to 23% was unlikely to be achieved (n = 222 out of planned 300). Thirty-day mortality was 37.5% (42/112) in cell recipients versus 42.7% (47/110) in control patients (relative risk [RR], 0.88; 95% confidence interval, 0.64-1.21; P = 0.43). There were no significant differences in days alive off ventilation within 60 days (median rank, 117.3 [interquartile range, 60.0-169.5] in cell patients and 102.0 [interquartile range, 54.0-162.5] in control subjects; higher is better). Resolution or improvement of acute respiratory distress syndrome at 30 days was observed in 51/104 (49.0%) cell recipients and 46/106 (43.4%) control patients (odds ratio, 1.36; 95% confidence interval, 0.57-3.21). There were no infusion-related toxicities and overall serious adverse events over 30 days were similar. Conclusions: Mesenchymal cells, while safe, did not improve 30-day survival or 60-day ventilator-free days in patients with moderate and/or severe COVID-19-related acute respiratory distress syndrome.

Real-world evidence of the safety and survival with CD19 CAR-T cell therapy for relapsed/refractory solid organ transplant-related PTLD.

The use of CD19 chimeric antigen receptor T-cell (CAR-T) therapy for relapsed/refractory solid organ transplantation (SOT)-related post-transplant lymphoproliferative disorder (PTLD) is not well studied. We conducted a multicentre, retrospective analysis of adults with relapsed/refractory SOT-associated PTLD. Among 22 relapsed/refractory SOT-PTLD patients, the pathology was monomorphic B cell. Prior SOTs included 14 kidney (64%), three liver (14%), two heart (9%), one intestinal (5%), one lung (5%), and one pancreas after kidney transplant (5%). The median time from SOT to PTLD diagnosis was 107 months. Pre-CAR-T bridging therapy was used in 55% of patients, and immunosuppression was stopped completely before CAR-T infusion in 64%. Eighteen (82%) patients experienced cytokine release syndrome: one (5%) each grade (G) 3 and G4. The immune effector cell-associated neurotoxicity syndrome was observed in 16 (73%) patients: six (27%) G3 and two (9%) G4. The overall response rate was 64% (55% complete response). Three patients (14%) experienced allograft rejection after CAR-T. The two-year progression-free survival and overall survival rates were 35% and 58%, respectively. Additionally, the achievement of CR post-CAR-T was strongly associated with survival. Collectively, the safety and efficacy of CD19 CAR-T therapy in relapsed/refractory SOT-related PTLD appeared similar to pivotal CAR-T data, including approximately one-third of patients achieving sustained remission.

Mesenchymal stromal cell therapy for acute respiratory distress syndrome due to coronavirus disease 2019.

BACKGROUND AIMS: The acute respiratory distress syndrome (ARDS) resulting from coronavirus disease 2019 (COVID-19) is associated with a massive release of inflammatory cytokines and high mortality. Mesenchymal stromal cells (MSCs) have anti-inflammatory properties and have shown activity in treating acute lung injury. Here the authors report a case series of 11 patients with COVID-19-associated ARDS (CARDS) requiring mechanical ventilation who were treated with remestemcel-L, an allogeneic MSC product, under individual patient emergency investigational new drug applications. METHODS: Patients were eligible if they were mechanically ventilated for less than 72 h prior to the first infusion. Patients with pre-existing lung disease requiring supplemental oxygen or severe liver or kidney injury were excluded. Each patient received two infusions of remestemcel-L at a dose of 2 million cells/kg per infusion given 48-120 h apart. RESULTS: Remestemcel-L infusions were well tolerated in all 11 patients. At the end of the 28-day follow-up period, 10 (91%, 95% confidence interval [CI], 59-100%) patients were extubated, nine (82%, 95% CI, 48-97%) patients remained liberated from mechanical ventilation and were discharged from the intensive care unit and two (18%, 95 CI%, 2-52%) patients died. The median time to extubation was 10 days. Eight (73%, 95% CI, 34-100%) patients were discharged from the hospital. C-reactive protein levels significantly declined within 5 days of MSC infusion. CONCLUSIONS: The authors demonstrate in this case series that remestemcel-L infusions to treat moderate to severe CARDS were safe and well tolerated and resulted in improved clinical outcomes.

Myocardial Amyloid Quantification with Look-Locker Magnetic Resonance Sequence in Cardiac Amyloidosis. Diagnostic Accuracy in Clinical Practice and Histological Validation.

BACKGROUND: Cardiac magnetic resonance (CMR) has demonstrated its utility in the noninvasive diagnosis of cardiac amyloidosis (CA). Our aim was to evaluate the ability of standard Look-Locker sequences to quantify amyloid deposition in CA. METHODS AND RESULTS: Consecutive patients referred for CMR for possible CA were retrospectively evaluated. Positive cardiac biopsy and/or typical pattern of late gadolinium enhancement were required for the diagnosis of CA. Postcontrast T1 values were obtained from Look-Locker sequences and correlated with markers of severity of disease and major events. When cardiac biopsies were available, histological validation was determined. A total of 174 patients were included. A final diagnosis of CA was reached in 37.4%. Myocardial and endocardial T1 times, as well as the respective ratios with blood and skeletal muscle, were lower among patients with CA and demonstrated good diagnostic performance. The best parameters were myocardial/blood (area under the curve 0.83; P < .001) and endocardial/blood (area under the curve 0.84; P < .001) T1 ratios. Among patients with CA, no associations were found between T1 ratios either with markers of amyloid burden or with prognostic variables. However, all T1 indexes showed significant correlations with histological quantification of amyloid deposition. CONCLUSIONS: Look-Looker derived postcontrast T1 shows good diagnostic accuracy to detect CA and correlation with histological amyloid burden.

Hematopoietic Stem Cell Transplantation for Multiple Myeloma: Guidelines from the American Society for Blood and Marrow Transplantation.

Therapeutic strategies for multiple myeloma (MM) have changed dramatically over the past decade. Thus, the role of hematopoietic stem cell transplantation (HCT) must be considered in the context of this evolution. In this evidence-based review, we have critically analyzed the data from the most recent clinical trials to better understand how to incorporate HCT and when HCT is indicated. We have provided our recommendations based on strength of evidence with the knowledge that ongoing clinical trials make this a dynamic field. Within this document, we discuss the decision to proceed with autologous HCT, factors to consider before proceeding to HCT, the role of tandem autologous HCT, post-HCT maintenance therapy, and the role of allogeneic HCT for patients with MM.

Identification of markers that functionally define a quiescent multiple myeloma cell sub-population surviving bortezomib treatment.

BACKGROUND: The mechanisms allowing residual multiple myeloma (MM) cells to persist after bortezomib (Bz) treatment remain unclear. We hypothesized that studying the biology of bortezomib-surviving cells may reveal markers to identify these cells and survival signals to target and kill residual MM cells. METHODS: We used H2B-GFP label retention, biochemical tools and in vitro and in vivo experiments to characterize growth arrest and the unfolded protein responses in quiescent Bz-surviving cells. We also tested the effect of a demethylating agent, 5-Azacytidine, on Bz-induced quiescence and whether inhibiting the chaperone GRP78/BiP (henceforth GRP78) with a specific toxin induced apoptosis in Bz-surviving cells. Finally, we used MM patient samples to test whether GRP78 levels might associate with disease progression. Statistical analysis employed t-test and Mann-Whitney tests at a 95% confidence. RESULTS: We report that Bz-surviving MM cells in vitro and in vivo enter quiescence characterized by p21(CIP1) upregulation. Bz-surviving MM cells also downregulated CDK6, Ki67 and P-Rb. H2B-GFP label retention showed that Bz-surviving MM cells are either slow-cycling or deeply quiescent. The Bz-induced quiescence was stabilized by low dose (500nM) of 5-azacytidine (Aza) pre-treatment, which also potentiated the initial Bz-induced apoptosis. We also found that expression of GRP78, an unfolded protein response (UPR) survival factor, persisted in MM quiescent cells. Importantly, GRP78 downregulation using a specific SubAB bacterial toxin killed Bz-surviving MM cells. Finally, quantification of Grp78(high)/CD138+ MM cells from patients suggested that high levels correlated with progressive disease. CONCLUSIONS: We conclude that Bz-surviving MM cells display a GRP78(HIGH)/p21(HIGH)/CDK6(LOW)/P-Rb(LOW) profile, and these markers may identify quiescent MM cells capable of fueling recurrences. We further conclude that Aza + Bz treatment of MM may represent a novel strategy to delay recurrences by enhancing Bz-induced apoptosis and quiescence stability.

Phase 1 study combining elotuzumab with autologous stem cell transplant and lenalidomide for multiple myeloma.

BACKGROUND: Autologous stem cell transplantation (ASCT) after induction therapy improves disease-free survival for patients with multiple myeloma (MM). While the goal of ASCT is to render a minimal disease state, it is also associated with eradication of immunosuppressive cells, and we hypothesize that early introduction of immunotherapy post-ASCT may provide a window of opportunity to boost treatment efficacy. METHODS: We conducted a phase 1 clinical trial to investigate the application of autologous lymphocyte infusion and anti-SLAMF7 monoclonal antibody, elotuzumab, after ASCT in patients with newly diagnosed MM previously treated with induction therapy. In addition to CD34+ stem cells, peripheral blood mononuclear cells were harvested prior to transplant and infused on day 3 after stem cell infusion to accelerate immune reconstitution and provide autologous natural killer (NK) cells that are essential to the mechanism of elotuzumab. Elotuzumab was administered starting on day 4 and then every 28 days after until 1 year post-ASCT. Cycles 4-12 were administered with standard-of-care lenalidomide maintenance. RESULTS: All subjects were evaluated for safety, and 13 of 15 subjects completed the treatment protocol. At 1 year post-ASCT, the disease status of enrolled subjects was as follows: five stringent complete responses, one complete response, six very good partial responses, one partial response, and two progressive diseases. The treatment plan was well tolerated, with most grade 3 and 4 AEs being expected hematologic toxicities associated with ASCT. Correlative analysis of the immune microenvironment demonstrated a trend toward reduced regulatory T cells during the first 3 months post-transplant followed by an increase in NK cells and monocytes in patients achieving a complete remission. CONCLUSIONS: This phase 1 clinical trial demonstrates that early introduction of immunotherapy after ASCT is well tolerated and shows promising disease control in patients with MM, accompanied by favorable changes in the immune microenvironment. TRIAL REGISTRATION NUMBER: NCT02655458.

CD19-Targeted Chimeric Antigen Receptor T-cell Therapy for Concomitant Diffuse Large B-cell Lymphoma and Multiple Myeloma.

Multiple myeloma (MM) and diffuse large B-cell lymphoma (DLBCL) comprise a large fraction of hematologic malignancies diagnosed each year. However, the co-occurrence of these conditions in the same patient is rare. CD19- and B-cell maturation antigen-targeted chimeric antigen receptor (CAR) T-cell therapies have been approved in recent years with promising responses. Here, we present a patient who presented following a bone marrow biopsy that revealed MM with 20% lambda-restricted plasma cells with no evidence of lymphoma involvement in the marrow. A subsequent lymph node biopsy of a right thigh mass was done and revealed DLBCL. The patient received CD19-targeted CAR T-cell therapy and has no detectable MM or DLBCL. To our knowledge, this is the first case report in the literature describing a patient with concomitant MM and DLBCL who received CD19-targeted CAR T-cell therapy.

Sustained expansion of NKT cells and antigen-specific T cells after injection of alpha-galactosyl-ceramide loaded mature dendritic cells in cancer patients.

Natural killer T (NKT) cells are distinct glycolipid reactive innate lymphocytes that are implicated in the resistance to pathogens and tumors. Earlier attempts to mobilize NKT cells, specifically, in vivo in humans met with limited success. Here, we evaluated intravenous injection of monocyte-derived mature DCs that were loaded with a synthetic NKT cell ligand, alpha-galactosyl-ceramide (alpha-GalCer; KRN-7000) in five patients who had advanced cancer. Injection of alpha-GalCer-pulsed, but not unpulsed, dendritic cells (DCs) led to >100-fold expansion of several subsets of NKT cells in all patients; these could be detected for up to 6 mo after vaccination. NKT activation was associated with an increase in serum levels of interleukin-12 p40 and IFN-gamma inducible protein-10. In addition, there was an increase in memory CD8+ T cells specific for cytomegalovirus in vivo in response to alpha-GalCer-loaded DCs, but not unpulsed DCs. These data demonstrate the feasibility of sustained expansion of NKT cells in vivo in humans, including patients who have advanced cancer, and suggest that NKT activation might help to boost adaptive T cell immunity in vivo.

Combining FDG-PET/CT with laboratory data yields superior results for prediction of relapse in multiple myeloma.

OBJECTIVES: The precise role of positron emission tomography (PET/CT) for predicting relapse/progression in multiple myeloma remains uncertain. We compared the predictive values of PET/CT, concurrent laboratory testing (labs), and their combination in prediction of 12-month progression, as determined by current International Myeloma Working Group (IMWG) criteria. METHODS: PET/CT and labs (serum chemistry, ß2-microglobulin, immunofixation, bone marrow biopsy, serum free light chains) were reviewed, and date of relapse/progression was determined by IMWG criteria. RESULTS: The median time from therapy to PET/CT imaging was 12.0 months (1.0-110) and median time to progression (TTP) was 29.8 months (1.6-130+). Overall survival and survival-without-progression at last follow-up were 84% and 49%, respectively. Sensitivity of PET/CT for predicting relapse/progression was lower than that of labs (0.67 vs. 0.89, ns), but PET/CT was more specific (0.89 vs. 0.79, ns). When labs and PET/CT data were combined, a positive result for either test was 89% sensitive and a positive result for both tests was 100% specific for predicting 12-month progression of disease. Kaplan-Meier analysis showed significantly greater TTP for those with a negative vs. positive PET/CT (P = 0.0005), negative vs. positive labs (P < 0.0001), and both tests negative vs. both tests positive (P < 0.0001). CONCLUSIONS: Combining PET/CT with laboratory data improves the accuracy of prediction of relapse/progression within 12 months compared with each test alone. Thus, integration of PET/CT into myeloma follow-up is recommended, and the impact of this approach on management should be explored.

Vigorous premalignancy-specific effector T cell response in the bone marrow of patients with monoclonal gammopathy.

Most approaches targeting the immune system against tumors have focused on patients with established tumors. However, whether the immune system can recognize preneoplastic stages of human cancer is not known. Here we show that patients with preneoplastic gammopathy mount a vigorous T cell response to autologous premalignant cells. This preneoplasia-specific CD4+ and CD8+ T cell response is detected in freshly isolated T cells from the BM. T cells from myeloma marrow lack this tumor-specific rapid effector function. These data provide direct evidence for tumor specific immune recognition in human preneoplasia and suggest a possible role for the immune system in influencing the early growth of transformed cells, long before the development of clinical cancer.

Non-myeloablative conditioning and allogeneic transplantation for multiple myeloma.

In multiple myeloma (MM), allogeneic stem cell transplantation (alloHCT) carries a lower relapse risk than autologous transplantation but a greater transplant-related mortality. Nonmyeloablative conditioning for allogeneic transplantation (NST) reduces transplant-related toxicity. Results are encouraging when used during first remission in low-risk patients, but less-so in relapsed or refractory disease. This is a single-center retrospective analysis of 20 previously treated MM patients who underwent NST from matched-related or matched-unrelated donors from 2000-2006. Median age was 52.7 years (37.2-68.0). Twenty-five percent had advanced or high-risk disease. Eleven still had active disease prior to NST. Conditioning was total body irradiation 200 cGy on a single fraction on day -5, followed by antithymocyte globulin (ATG) 1.5 mg/kg/day and fludarabine 30 mg/m(2)/day on days -4 to -2. All received immunosuppression, most commonly with oral mycofenylate mofetil and cyclosporine beginning on day -5. At day 100, 50% had achieved complete remission. Transplant-related mortality was 25%. Median overall survival (OS) was 21.2 months (0.6-90+) and progression-free survival (PFS) 6.6 months (0.6-90+). Both OS and PFS were 24% at 3 years. OS was significantly greater for patients with age <52 years (median 27 months vs. 7.9 months, P = 0.031), and there was a trend toward greater OS for those with beta2 microglobulin <2.5 mg/l (median 27 months vs. 7.7 months, P = 0.08). Donor characteristics and Ig type had no significant effect on survival. These data suggest a benefit of NST in relapsed/refractory MM. Randomized trials must be performed to confirm and further qualify this benefit.

Bendamustine With Dexamethasone in Relapsed/Refractory Systemic Light-Chain Amyloidosis: Results of a Phase II Study.

PURPOSE: No established treatments exist for relapsed/refractory systemic light-chain (AL) amyloidosis. Bendamustine has shown potential in the treatment of multiple myeloma. We conducted a phase II, multicenter trial to assess the efficacy and safety of bendamustine with dexamethasone (ben-dex) in patients with persistent or progressive AL amyloidosis after ≥ 1 prior therapy. METHODS: The trial enrolled 31 patients who received bendamustine on days 1 and 2 (100 mg/m2 intravenously) with 40 mg of weekly dexamethasone in 28-day cycles until disease progression or up to 6 cycles after complete hematologic response. The primary objective was the rate of partial hematologic response (PR) or better. RESULTS: Patients received a median of 4 cycles (range, 2-12 cycles) with 57% of patients achieving a PR or better (11% complete response, 18% very good PR). The overall organ response was 29% among the 24 patients who had measurable organ involvement. Treatment was well tolerated with no grade 5 treatment-related adverse events (AEs). Sixty-five percent of patients had a therapy-related grade 3-4 AE. The most common AEs included myelosuppression, fatigue, and nausea/vomiting. The median overall survival was 18.2 months (95% CI, 11.3 to 43.8 months), and hematologic response was associated with prolonged survival (P = .0291). The median progression-free survival was 11.3 months (95% CI, 5.0 to 15.4 months). CONCLUSION: Overall, ben-dex is a viable treatment option with substantial efficacy and limited toxicity for patients with pretreated AL amyloidosis who have limited therapeutic options. This trial was registered at (ClinicalTrials.gov identifier: NCT01222260).

Combined bone marrow and peripheral blood progenitor cell autografts for patients with poor mobilization.

BACKGROUND AIMS: Peripheral blood progenitor cell (PBPC) autografts with low CD34(+) cell content provide inadequate platelet (Plt) and red blood cell (RBC) reconstitution. Repeat collection and bone marrow (BM) harvesting are used in this situation. Minimum cell contents for BM-PBPC combined grafts are undefined. METHODS: A retrospective analysis of 19 autologous stem cell transplants (ASCT) with combined BM-PBPC for poor initial PBPC collection was carried out. Mobilization was with filgrastim (10 microg/kg/day) alone for 5 days or after chemotherapy. BM was harvested if PBPC collections were CD34+<2.5 x 10(6)/kg. RESULTS: The median age was 55 years (range 19-74). The diagnoses were multiple myeloma (7), non-Hodgkin's lymphoma (7), Hodgkin's disease (4) and acute myeloid leukemia (1). The median cell content (CD34+/kg x 10(6)) was 1.1 (0.3-2.7) for BM, 1.2 (0.04-2.8) for PBPC and 2.2 (1.4-4.9) combined. Eight grafts contained <2.0 x 10(6) CD34+/kg (1.4-1.8). The median engraftment in days (range) was: absolute neutrophil count (ANC) > 500, 12 (9-39); Plt > 20 000, 25 (15-70); RBC transfusion independence, 17 (6-93). Six patients died of progressive disease (58-293 days post-ASCT), one of infection on day 141 and one of AML on day 11. All patients except one maintained ANC > 1000 without filgrastim support beyond day 19. One patient had cholecystitis and delayed graft failure on day 90. PBPC CD34+ content did not predict CD34+ BM content but correlated with ANC > 500 (r= - 0.64, P=0.003). BM and combined CD34+ and BM TNC/kg did not correlate with engraftment or outcomes. Combined CD34+/kg < or > = 2.0 x 10(6) produced similar engraftment and mortality. CONCLUSIONS: After a failed PBPC collection, BM harvest is a reliable option for obtaining an adequate combined autograft. Combined BM-PBPC autografts with <2.0x10(6) CD34+/kg can produce satisfactory engraftment.

Graft versus host disease after stem cell allotransplantation with low-dose total body irradiation, fludarabine, and antithymocyte globulin.

BACKGROUND: We previously showed that antithymocyte globulin (ATG) given with total body irradiation (TBI) 200 cGy and fludarabine results in high rate of donor engraftment. Its influence on acute and chronic graft versus host disease (GVHD) and on graft versus tumor effect is less known. METHODS: Sixty-five patients underwent nonmyeloablative stem cell transplant with ATG, TBI 200 cGy, and fludarabine. GVHD prophylaxis was mycophenolate mofetil and cyclosporine. Forty-two patients (pts) (65%) had match related donors, 18 (27%) match unrelated, 1 (1.5%) mismatch related, and 4 (6%) mismatch unrelated donors. RESULTS: At a median follow-up of 862 days, 24 patients (37%) developed GVHD. The median age of the patients with and without GVHD was 56 years respectively. Acute GVHD grade II-IV developed in 19 pts (29%). Fatal GVHD of liver and/or gut occurred in nine pts (14%). Forty-one pts survived more than 100 days. Five pts (12%) had chronic GVHD, two had extensive, and three had limited involvement. Relapsed disease was observed in 22 pts (34%). Infections occurred in 15 pts (23%) and were fatal in 13 (20%). CONCLUSIONS: The addition of ATG to TBI 200cGy and fludarabine resulted in a modest incidence of GVHD. The best transplant outcomes were observed in pts with lymphoid malignancies.

Expression of cancer/testis (CT) antigens MAGE-A1, MAGE-A3, MAGE-A4, CT-7, and NY-ESO-1 in malignant gammopathies is heterogeneous and correlates with site, stage and risk status of disease.

Cancer/testis (CT) antigens are expressed in several malignant tumors, but not in normal tissues except for testicular germ cells. The expression of CT antigenic proteins in malignant gammopathies has not been characterized. We examined the expression of a panel of CT antigenic proteins in 29 patients with malignant gammopathies by immunohistochemistry using the following monoclonal antibodies (mAbs): mAb MA454 to MAGE-A1, mAb M3H67 to MAGE-A3, mAb 57B to MAGE-A4, mAb CT7-33 to CT7/MAGE-C1 and mAb ES121 to NY-ESO-1. We could detect at least one CT antigen in tumors from 27 of 29 patients. The expression pattern of MAGE-A1, -A3, -A4 and NY-ESO-1 is heterogeneous in most cases, revealing staining in <25% of the tumor cells. Monoclonal antibodies CT7-33 and M3H67 show the highest incidence of immunoreactivity. Importantly, CT-7 can also be detected on the surface of some myeloma cells by flow cytometry, and in one plasmacytoma case by immunohistochemistry. Expression of CT antigens is greater in patients with stage III extramedullary plasmacytoma or high-risk myeloma relative to other cohorts. These data suggest that CT antigens may have important biological implications in malignant gammopathies and that CT-7 may be a suitable target for T cell-based and possibly antibody-mediated immunotherapy of myeloma.