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Chronic graft-versus-host disease (cGVHD) is characterized by a state of profound immunodeficiency in association with alloreactive and autoimmune phenomena. These observations indicate an impairment of immunologic tolerance that could involve both central and peripheral mechanisms. Defective thymic function may contribute to dysregulation of central tolerance, but few studies have addressed peripheral tolerance. Recently a population of CD4+CD25+ T cells (Treg cells) has been characterized, which controls immunologic reactivity in vivo and which on transfer can prevent experimental acute GVHD. We investigated the number and function of peripheral blood CD4+CD25high T cells in patients more than 100 days after allogeneic hematopoietic stem cell transplantation. Patients with cGVHD had markedly elevated numbers of CD4+CD25high T cells as compared to patients without GVHD. CD4+CD25high T cells derived from patients in both groups were of donor origin, lacked markers of recent activation, and expressed intracellular CD152. In contrast to controls, CD4+CD25high T cells derived from patients with cGVHD were characterized by lower surface CD62L expression. In vitro, CD4+CD25high T cells were hyporesponsive to polyclonal stimulation and suppressed the proliferation and cytokine synthesis of CD4+CD25- cells, an effect that was independent of interleukin 10. These results indicate that chronic graft-versus-host injury does not occur as a result of Treg cell deficiency.

Killer immunoglobulin–like receptors (KIRs) regulate cell activity of natural killer (NK) cells and some T cells. The predominant ligand for inhibitory KIRs is HLA-C, which subdivides into 2 groups based on the specificity of inhibitory KIRs. The ligands for activatory KIRs are unknown. Following hematopoietic stem cell transplantation (HSCT), recipient tissues may not express a ligand for KIRs present within the graft, and the combination of donor KIR and recipient HLA-C types could influence outcome. HLA and KIR genotypes were determined in 220 donor-recipient pairs from HLA-matched sibling HSCTs performed for myeloid (n = 112) and lymphoid (n = 108) diseases. In HSCTs performed for myeloid disease, overall survival was worse in patients homozygous for group 2 HLA-C (C2) than in patients who carried a group 1 HLA-C (C1) allele (P < .005). Moreover, this effect is seen only when the donor additionally carries the activating KIR gene KIR2DS2 (P = .045). No effect was seen in patients with lymphoid disease. Thus, in HLA-matched sibling HSCT for myeloid leukemia, patients homozygous for C2 alleles receiving a graft from a donor carrying the KIR gene KIR2DS2 have a significantly reduced chance of survival.

A nonmyeloablative conditioning regimen was investigated in 47 patients with hematological malignancy receiving allogeneic progenitor cells from matched, unrelated donors. The median patient age was 44 years. The majority of patients had high-risk features, including having failed a prior transplantation (29 individuals). Twenty of the transplants were mismatched for HLA class I and/or class II alleles. Recipient conditioning consisted of 20 mg CAMPATH-1H on days −8 to −4, 30 mg/m2fludarabine on days −7 to −3, and 140 mg/m2 melphalan on day −2. Graft-versus-host disease (GVHD) prophylaxis was with cyclosporine A alone. Primary graft failure occurred in only 2 of 44 evaluable patients (4.5%). Chimerism studies in 34 patients indicated that the majority (85.3%) attained initial full donor chimerism. Only 3 patients developed grade III to IV acute GVHD, and no patients have yet developed chronic extensive GVHD. The estimated probability of nonrelapse mortality at day 100 was 14.9% (95% confidence interval [CI], 4.7%-25.1%). With a median follow-up of 344 days (range, 79-830), overall and progression-free survivals at 1 year were 75.5% (95% CI, 62.8%-88.2%) and 61.5% (95% CI, 46.1%-76.8%), respectively. In summary, a nonmyeloablative regimen incorporating in vivo CAMPATH-1H is effective in promoting durable engraftment in most patients and in reducing the risk of severe GVHD following matched unrelated donor transplantation.

Reactivation of cytomegalovirus (CMV) is a common complication following allogeneic stem cell transplantation. Genetic determinants in the host and donor that may influence the rate of reactivation are currently unknown. Viral replication is controlled by T cells and natural killer (NK) cells and these share expression of killer immunoglobulin-like receptors (KIRs). We analyzed whether activatory KIRs carried by the donor influenced the subsequent rate of CMV reactivation in the patient. In transplantations involving siblings where both donor and recipient were CMV seropositive, donors with more than one activating KIR gene were associated with a 65% reduction in CMV reactivation. Multivariate analysis confirmed a significantly reduced risk of CMV reactivation in sibling transplantations where the donor had more than one activating KIR. Reduced-intensity transplantation and graft-versus-host disease grade 2 or higher were associated with an increased risk of CMV reactivation. This observation indicates that activating KIRs play an important role in the cellular control of CMV reactivation.

Abstract 3007FN2 Background: Epstein-Barr virus (EBV) associated post-transplant lymphoproliferative disease (PTLD) is an important complication of allogeneic stem cell transplantation (alloSCT). Quantitative PCR monitoring of EBV genomes in blood and pre-emptive administration of Rituximab in patients with high viral load is emerging as a strategy to reduce mortality from PTLD. However, factors predicting for response in this patient population are not well understood. Aim: To report the frequency and characteristics of patients treated for EBV reactivation and to identify factors predicting outcome. Methods: This retrospective analysis examined all patients needing treatment with Rituximab for EBV reactivation after undergoing alloSCT at University Hospital Birmingham, UK between June 2009 and February 2011. A total of 92 T-deplete and 9 cord blood transplant patients were monitored weekly with quantitative EBV PCR testing of whole blood for a minimum of 6 months. Patients with EBV reactivation were given Rituximab pre-emptively when viral DNAemia exceeded 30, 000 copies/ml, whereas patients presenting with PTLD were treated irrespective of viral load. A maximum of 4 weekly doses of Rituximab 375mg/m2 were given until PCR negativity or resolution of symptoms. Cases of PTLD were either biopsy-proven or diagnosed as probable PTLD if viral DNAemia was associated with clinicoradiologic evidence of disease. Results: Of 101 patients undergoing alloSCT monitored by quantitative EBV PCR testing 24 (24%) were treated with Rituximab for EBV reactivation. The median age of treated patients was 58 years and 75% were male. Two patients received myeloablative and 22 received reduced intensity conditioning. Donor stem cells were sibling in 6, unrelated in 14 and cord blood in 4 patients. EBV DNAemia over 30, 000 copies/ml occurred in 23 of 24 treated patients. Of these, 14 had no evidence of PTLD whilst 9 of 23 had evidence of either probable (6 cases) or biopsy-proven (3 cases) PTLD at the time of initiating treatment. One patient was treated for biopsy-proven PTLD with a viral load that never exceeded 30, 000 copies/ml. The median interval from alloSCT to first PCR positivity was 99 days (IQR 70 – 146 days) and the median interval from first PCR positivity to exceeding the 30, 000 copies/ml threshold was only 7 days (IQR 0 – 14 days). Notably, treated patients with PTLD became PCR positive significantly earlier after alloSCT than those without PTLD (median 71 vs. 119 days; p=0.01*). Median viral loads at first PCR positivity, at the 30, 000 copies/ml threshold and at peak viral load were 1.1×104, 8.2×104 and 2.2×105 copies/ml respectively, of which peak viral load was significantly higher in patients with PTLD (median 1.1×106 vs. 1.4×105 copies/ml; p=0.01*). Patients reactivating EBV without PTLD received a median of 3 doses of Rituximab whilst patients with PTLD received a median of 4 doses. Complete response (defined by PCR negativity and clinioradiologic resolution of disease) was seen in 13/14 (93%) patients without PTLD versus 6/10 (60%) patients with PTLD. Notably, among patients who achieved PCR negativity the median interval from initiation of treatment to PCR negativity was significantly longer in those with PTLD (median 28 vs. 13 days; p=0.005*). All 4 patients with Rituximab-refractory PTLD died despite further treatment with chemotherapy in 3 cases. All-cause mortality for treated patients was 10/24 (42%). Regarding predictors of response to Rituximab, a diagnosis of PTLD at treatment initiation showed a clear tendency to significance (p=0.056**) whilst raised CRP >30 was highly significant (p=0.003**). Other variables including age, sex, conditioning, donor type, viral load, LDH and albumin were not significant. Conclusions: Focussing exclusively on alloSCT patients treated with Rituximab under a pre-emptive management strategy, this study demonstrates that patients who require treatment typically display an early and vigorous EBV DNAemia. Notably, among patients treated for EBV reactivation those with PTLD become EBV PCR positive earlier, have higher peak viral loads and take longer to reach PCR negativity after treatment. Rituximab responsiveness is a key determinant of outcome, as patients with refractory disease have poor survival irrespective of chemotherapy. Among patients who reactivate, those with PTLD or with raised CRP experience inferior outcomes. *Mann-Whitney U Test **Fisher's Exact Test Disclosures: No relevant conflicts of interest to declare.

Abstract 2361 Introduction: Reduced intensity allogeneic transplants represent a potentially curative therapy in older patients with haematological malignancies. However the upper age limit for transplantation using a sibling or unrelated donor is unclear and few studies have addressed this important issue. In the UK in vivo T cell depletion utilising alemtuzumab is commonly used as a strategy to reduce the risk of acute and chronic graft-versus-host disease (GVHD) but this manoeuvre impairs immune reconstitution and may pose a particular problem in older patients. Aim: We analysed the outcome of patients over the age of 60 after an alemtuzumab based reduced intensity allograft from five UK Transplant Centres with the aim of identifying factors determining long term outcome and also factors affecting the duration of inpatient admission during the first 100 days post transplant. A modified Charlson's comorbidity index score (Sorror modified HCT comorbidity index) was applied to analyse the transplant outcomes of these patients according to the presence of transplant co-morbidities. Patients and Methods: We have studied the outcome of 161 patients (89 male, 72 female) after an alemtuzumab conditioned reduced allograft allograft for a haematological malignancy. The median age of the patients was 62 years(range 60–72). 115 patients had a transplant for myeloid malignancies (87 acute myeloid leukaemia, 21 myelodysplastic syndrome, 2 chronic myeloid leukaemia, 5 myelofibrosis) and 46 for lymphoid malignancies (18 Non_Hodgkin's lymphoma, 14 chronic lymphocytic leukaemia, 4 T-prolymphocytic leukaemia, 7 multiple myeloma and 3 acute lymphoblastic leukaemia). 93 patients received an unrelated donor transplant and 68 had a sibling transplant. The great majority of patients were transplanted using a Fludarabine/Melphalan conditioning regimen(n=118) whilst 13 received a combination of fludarabine and busulphan, 21 BEAM (BCNU, cytarabine, etoposide, melphalan) and 9 a combination of BEAM and fludarabine. The median follow up was 19.1 months (range 2–94 months). Results: The one year overall survival for the whole group was 52% and the predicted two year OS 46%. The transplant related mortality (TRM) was 19% in the first 100 days post transplant and 23% in the first year post transplant. 40 patients (25%) relapsed. 25 patients (21%) developed Grade III-IV acute GvHD and 16 (10%) patients developed chronic extensive GvHD. There was a weakly negative correlation between Age and Bed Days(p:0.05843) but the correlation between high comorbidity index (3 or greater than 3) and increased bed days is significant(P:0.0013). Transplant outcomes were affected by Sorror modified comorbidity index for HCT.A score of 3 and above was significantly associated with decreased overall survival (P:0.001) and interestingly with decreased disease free survival (P:0.02). CMV status and stem cell dose did not have any impact on overall survival and disease free survival and CR1 at transplantation was showed a trend towards increased overall survival(P:0.05). Conclusions: Reduced intensity alemtuzumab based stem cell transplant can be delivered safely in patients above the age of 60. It appears that a Sorror comorbidity score of 3 and above has a negative impact on overall survival and disease free survival of these patients and significantly increases inpatient days.These observations require confirmation in a larger cohort of patients but suggest that the selection of patients above the age of 60 for a reduced intensity transplants will be facilitated by incorporation of the Sorror HCI comorbidity index into a transplant algorithm. Disclosures: No relevant conflicts of interest to declare.

Epstein-Barr virus (EBV)-associated lymphoproliferative disease (LPD) is an uncommon but potentially fatal complication of allogeneic haematopoietic stem cell transplantation (SCT), usually presenting within 6 months post-transplant. Diagnosis of LPD may be difficult as the clinical picture can mimic sepsis or severe GvHD without obvious lymphadenopathy. High blood EBV load is a useful diagnostic feature but in isolation has limited positive predictive value for LPD. We report 2 patients in whom expansion of CD38+ activated B cells in peripheral blood was an important diagnostic feature of EBV-associated LPD developing early after T- deplete myeloablative allogeneic SCT. The first patient, a 39 year old female with relapsed acute lymphoblastic leukaemia, presented 4 months after an unrelated donor SCT with a febrile illness in association with EBV and adenovirus reactivation (5.7 x 105 and 2.6 x 106 copies/ml of blood respectively). There was no evidence of lymphadenopathy either clinically or on imaging. Following Cidofovir treatment there was a log reduction in the adenovirus load but EBV load increased coupled with a rising peripheral blood lymphocyte (PBL) count from 0.2 x 109/l to 3.2 x 109/l. The patient died soon after from multi-organ failure. The second patient, a 19 year old female with acute myeloid leukaemia, presented 2 months after a haplo-identical SCT with a similar clinical picture and EBV load of 2 x 107 copies. Her PBL count increased rapidly from 0.5 x 109/l to 11.3 x 109/l. Cell marker studies in both patients revealed B-lymphoproliferation with CD19+ B cells constituting 80% of PBL with a profound reduction in NK and T cell numbers. The B cells displayed an abnormal activated phenotype with strong CD38 expression and were CD20+, CD22+, CD79b+, CD5neg, CD10neg, and CD103neg. Concomitant CD23 expression was noted in a proportion of B cells and a minority expressed CD34. Clonal IgH gene rearrangement was noted in the second patient; furthermore, elispot assays demonstrated a complete absence of EBV-specific CD8 T cell immunity. This patient received 2 doses of Rituximab with a log reduction in EBV load, but succumbed to overwhelming sepsis-like syndrome. In both patients, a rising PBL count due to expansion of activated CD38+ B cells was an important manifestation of EBV-associated LPD in the absence of obvious lymphadenopathy or organomegaly. This response pattern is in sharp contrast to that seen in immunocompetent patients with infectious mononucleosis (IM) where lymphocytosis is due to proliferation of CD8+ T rather than B cells. Interestingly, our recent work on tonsils from IM patients has identified CD38 expression as a useful marker for B cells activated by EBV infection and it is likely that the abnormal B cells noted in the above two patients represent the same. Our experience emphasises the usefulness of peripheral blood cell marker studies in evaluating patients with suspected early onset PTLD following SCT. An expansion of CD38+ activated B cells and absence of T cell response can be useful diagnostic features which can aid in making treatment decisions in this difficult situation.

SGN-30 is a monoclonal antibody directed against the CD30 antigen expressed on some hematologic malignancies. Based on encouraging phase I data, a multicenter phase II study was conducted treating patients with refractory or recurrent CD30-positive ALCL with an ECOG performance status of ≤ 2. Thirty-nine patients (24M, 15F) with ALCL were enrolled, with a median age of 57 (range 23–82) and a median of 3 prior therapies (range 2–5). Nine patients had previously received a stem cell transplant. Eighty-five percent of tumors were negative for ALK, a poor prognostic factor. SGN-30 was administred at 6 mg/kg/wk (90 minute infusion, premedications were not required) for 6 consecutive weeks. After 24 patients were enrolled, the dose was escalated to 12 mg/kg/wk in subsequent patients. (Patients with stable disease or objective response were eligible to receive additional cycles of SGN-30. Five patients received ≥ 2 cycles of SGN-30.) Response assessments, as determined by CT scans, were performed 2 weeks after the last infusion. Best response is shown below: CR PR SD PD Pending Eval ORR *Both CRs have ongoing durations of >365 days; both patients received additional cycles of SGN-30. **PRs had durations of 27, 53, 139 and 167 days; two additional patients have ongoing durations of 86+ and 25+ days. ***Three SDs have ongoing durations of 96+, 365+, and 365+ days. Two additional patients had SD for 71 and 174 days. 2* 6** 5*** 24 2 21% Three drug-related toxicities ≥ Grade 3 were reported (each was considered possibly related to SGN-30): 1) lymphopenia, 2) catheter related infection and 3) urticaria. No other significant hematologic or biochemical toxicities have been observed. There was one definitely related serious adverse event (Grade 2) in a patient who experienced a transient exacerbation of his cutaneous lesions after 2 doses of SGN-30 but achieved a partial response after continuing on study. This phase II study represents one of the largest prospectively designed trials in relapsed/refractory ALCL and demonstrates good tolerability and clinically meaningful antitumor activity of SGN-30, especially in ALK negative patients who have a particularly poor prognosis.

The use of short-duration intensive combination chemotherapy protocols has improved survival in adults with Burkitt/Burkitt-like leukaemia and lymphoma (BL). Systemic methotrexate (MTX) is an integral component of these regimens, but the dosage varies between treatment schedules, and the precise dose required to optimise tumour-kill without causing severe toxicity is not known. In this study of 66 adults with sporadic BL, we have investigated whether the dosing intensity of MTX can influence treatment failure (defined as disease relapse or resistance to treatment, or death due to therapy). There were 49 males and 17 females in the cohort (median age 36 years, range 16–69y), including 9 with HIV disease and 2 organ-transplant recipients. Majority of patients (66%) had St Jude stage III/IV disease. The median increase in serum LDH level relative to normal (adjusted LDH) was 1.4 (range 1–65). Patients were treated with a combination of CNS-directed and systemic chemotherapy comprising of a pre-phase [fractionated (Fr) cyclophosphamide and prednisolone], followed by a possible total of 6 cycles of alternating Fr ifosfamide, dexamethasone, vincristine, cytarabine and etoposide [Cycle A], with Fr cyclophosphamide, dexamethasone, vincristine and adriamycin [Cycle B] as outlined by the German BFM paediatric protocols. Patients received a 24h intravenous infusion of MTX on d1 of each cycle of treatment. Based on the mean MTX dose administered per cycle, patients were stratified into three dosage groups: low (1.5–3g/m2, n=34). There were 3 toxic deaths, disease was refractory in 8 patients and 9 experienced disease relapse. Durable complete responses following BFM were observed in 46/66 (70%) patients. A significantly lower proportion of patients receiving high-dose MTX (17%) experienced treatment failure compared to 45% and 50% in the intermediate and low-dose groups respectively (Fisher’s Exact p=0.01). Risk stratification on the basis of pre-treatment stage and bulk of disease, adjusted LDH and ECOG score was however unable to identify patients who may benefit from intensifying MTX dosage. These data thus uniquely highlight the impact of MTX dose in influencing outcomes in adult BL as well as the need for novel biological markers to identify patients requiring additional therapeutic strategies.

Background. Varicella zoster virus (VZV) reactivation is a common occurrence after allogeneic haematopoietic stem cell transplant (HSCT) and a cause of significant morbidity. We have recently demonstrated the protective effect of donor KIR genotpye against cytomegalovirus (CMV) reactivation- specifically the protective effect of the broad ’B’ haplotype containing multiple activating KIR genes1. This retrospective study was designed to investigate whether donor KIR genotype confers an equivalent protective effect against VZV reactivation. Method. 152 patients who underwent allogeneic HSCT at a single centre were identified. Those with pre-transplant serology consistent with previous exposure to VZV were defined as at risk of VZV reactivation. All patients received aciclovir 800mg daily as routine prophylaxis. The diagnosis of VZV reactivation was made clinically. Cases of VZV reactivation were identified by examination of the case records. KIR genotyping was performed on donor DNA using PCR-SSP. The individual KIR genes KIR2DL1, 2DL2, 2DL3, 2DL5, 3DL1, 2DS1, 2DS2, 2DS3, 2DS4, 2DS5 and 3DS1, as well as the broad KIR haplotypes ’A’ and ’B’, were assessed by univariate and multivariate analysis for an effect on VZV reactivation. Also assessed was the impact of recipient HLA-C type, recipient HLA-Bw4/Bw6, donor type (sex-matched sibling, sex-mismatched sibling, volunteer unrelated), reduced intensity conditioning (RIC) regimen, the use of alemtuzemab as in vivo T cell depletion, CMV reactivation, and grade 2 or greater GVHD requiring steroid therapy. Results. 128 (84.2%) patients had evidence of past infection and thus were deemed at risk of VZV reactivation. Of these, 47 (36.7%) had clinical evidence of reactivation. 60% of transplants were from a donor possessing the broad ’B’ haplotype. The rate of reactivation in the presence of donor ’B’ haplotype was 40% compared to 32% when no donor ’B’ haplotype was present (p=0.237). None of the individual donor KIRs were shown to significantly reduce the rate of VZV reactivation. Neither the use of a RIC regimen nor the presence of alemtuzemab in the conditioning regimen were shown to have an impact. None of the other factors analysed were associated with an increased rate of zoster reactivation. Conclusion. Donor KIR genotype does not influence VZV reactivation after allogeneic HSCT. This contrasts with the findings for CMV reactivation. No influence of donor type, conditioning or GVHD could be demonstrated. This suggests 1) that there are differing mechanisms that control the reactivation of different Herpes viruses after transplantation and 2) that KIRs may have specificity for CMV.

Background CMV reactivation is the commonest viral complication following allogeneic stem cell transplantation (SCT) and is a direct consequence of immunodeficiency. Natural killer (NK) and T-cells are the primary effector populations that suppress CMV replication. Killer immunoglobulin-like receptors (KIRs) are expressed on the surface of NK cells and T-cell subsets. Inhibitory KIRs have specificity for defined alleles of class I HLA and deliver an inhibitory signal to the cell. Activating KIRs bind weakly to HLA molecules and their true ligands remain unknown. KIR genes are polymorphic. Two broad haplotypes exist which differ in the number of activatory KIR genes that they contain. Haplotype A has 1 activatory KIR gene whereas haplotype B contains additional activatory genes. Methods We studied 107 patients undergoing allogeneic SCT at 3 UK Institutions to evaluate the effect of activating KIRs on CMV reactivation. Two thirds received standard myeloablative conditioning with TBI/Cy or Bu/Cy. One third received non-myeloablative conditioning. Recipient/donor CMV sero-status was determined by ELISA. Reactivation was defined as two successive PCR assays detecting >400 copies/ml. KIR genotyping was performed by PCR-SSP. Results In CMV seropositive recipients, the CMV reactivation rate was 50% in transplants from sibling donors and 64% in transplants from unrelated or HLA non-identical donors. In sibling transplants where both donor and recipient were CMV seropositive and the donor was homozygous for KIR Haplotype A (group A) the CMV reactivation rate was 65% .In contrast if the donor possessed at least one KIR haplotype B (group B) the reactivation rate was reduced to 27.5% (p=0.014). The protective effect of group B donors was seen only in patients who received a myeloablative non-T-depleted transplant. Here, the reactivation rate was 70.6% (12 from 17) when transplanted from a group A donor compared with 23.8% (5 from 21) when transplanted from a group B donor (p=0.0039). If a group B donor was used no reactivation was seen after 41 days, whereas in transplants from group A donors the risk of reactivation continued until day 100 (figure 1,p=0.018). The donor KIR genotype did not influence CMV reactivation rates in patients who received T-depleted grafts from sibling, unrelated or haploidentical donors. Conclusion In T-cell replete sibling donor transplants the use of a donor with multiple activating KIRs significantly reduces the risk of CMV reactivation when both donor and recipient are CMV seropositive. This is the first direct evidence of activating KIRs exerting a controlling effect on CMV in humans.

Proteins from the family known as ‘cancer-testis antigens’ (CTAg) are expressed in some cases of multiple myeloma and subsets of acute myeloid leukaemia. CTAg can stimulate CD8+ T cell responses in patients with melanoma but there are no reports of CTAg-specific immune response in patients with haematological malignancy. Such information is critical to assess whether or not these antigens act as targets for tumour-specific immunity or if they could be used as targets for immunotherapy. We have used twelve peptide epitopes from a range of cancer-testis antigens which have been previously defined as epitopes for CD8+ T cells. These were used to screen for tumour-specific T-cells in blood of patients with multiple myeloma at various stages of their disease. The IFNγ cytokine secretion assay was used to detect functional responses and magnetic selection was employed to increase the sensitivity of detection. FACS analysis was used to quantitate the frequency of responding cells. 37 patients were screened with an age range of between 45 and 88 years. Blood samples were taken at monthly intervals and the percentage of CD8+ T cells responding to each peptide was calculated. 13 patients responded to 1 or more of the peptides with a range between 0.01% and 0.7% of the total CD8+ T cell pool. The frequency of the tumour-specific response fluctuated during treatment in individual patients. Analysis of the CTAg-specific immune response in relation to disease course revealed that the immune response was generally correlated with tumour burden as revealed by the paraprotein level. CTAg HLA-peptide tetramers incorporating peptides from LAGE-1 and MAGE-2 were able to directly visualize CTAg-reactive T cells in PBMC. CTAg-specific CD8+ T cells may have been primed and expanded by expression of CTAg on tumour cells or following ‘cross presentation’ through dendritic cells. In conclusion, T cells specific for cancer-testis antigens are present in the blood of a subset of patients with multiple myeloma. The clinical significance of this observation is currently being addressed.