Conversion to full donor chimerism following donor lymphocyte infusion is associated with disease response in patients with multiple myeloma

Cellular Immunotherapy for Multiple Myeloma

Cellular immunotherapy for myeloma has the unique potential both to potently kill the malignant clone and to evoke a memory response to protect from relapse. Understanding the complex interactions between the malignant clone and the microenvironment that promote immune escape is critical to evoke effective antimyeloma immunity. Tremendous progress has been made in the area of cancer vaccines and adoptive T-cell therapy in recent years. Careful study of the mechanisms of response and of immune escape will be critical to developing novel combination therapies and ultimately to improve outcomes for patients with myeloma.

Recipient and donor cells in the graft-versus-solid tumor effect: It takes two to tango

Allogeneic hematopoietic stem cell transplantation (alloHSCT) produces -similar to the long-established graft-versus-leukemia effect- graft-versus-solid-tumor effects. Clinical trials reported response rates of up to 53%, occurring mostly but not invariably in association with full donor chimerism and/or graft-versus-host disease. Although donor-derived T cells are considered the principal effectors of anti-tumor immunity after alloHSCT or donor leukocyte infusion (DLI), growing evidence indicate that recipient-derived immune cells may also contribute. Whereas the role of recipient-derived antigen-presenting cells in eliciting graft-versus-host reactions and priming donor T cells following DLI is well known, resulting inflammatory responses may also break tolerance of recipient effector cells towards the tumor. Additionally, mouse studies indicated that post-transplant recipient leukocyte infusion produces anti-leukemia and anti-solid-tumor effects that were exclusively mediated by recipient-type effector cells, without graft-versus-host disease. Here, we review current preclinical and clinical evidence on graft-versus-solid-tumor effects and growing evidence on the effector role of recipient-derived immune cells in the anti-tumor effect of alloHSCT.

Allograft for Myeloma: Examining Pieces of the Jigsaw Puzzle

Multiple myeloma (MM) cure remains elusive despite the availability of newer anti-myeloma agents. Patients with high-risk disease often suffer from early relapse and short survival. Allogeneic hematopoietic cell transplantation (allo-HCT) is an “immune-based” therapy that has the potential to offer long-term remission in a subgroup of patients, at the expense of high rates of transplant-related morbidity and mortality. Donor lymphocyte infusion (DLI) upon disease relapse after allo-HCT is able to generate an anti-myeloma response suggestive of a graft-versus-myeloma effect. Allo-HCT provides a robust platform for additional immune-based therapy upon relapse including DLI and, maintenance with immunomodulatory drugs and immunosuppressive therapy. There have been conflicting findings from randomized prospective trials questioning the role of allo-HCT. However, to this date, allo-HCT remains the only potential curable treatment for MM and its therapeutic role needs to be better defined especially for patients with high-risk disease. This review examines different aspects of this treatment and summarizes ongoing attempts at improving its therapeutic index.

CAR T cell therapy for multiple myeloma: where are we now and where are we headed?

While recent progress has been made in the management of multiple myeloma, it remains a highly fatal malignancy especially among patients with relapsed-refractory disease. Immunotherapy with adoptive T cells targeting myeloma-associated antigens are at various stages of development and have brought about a new hope for cure. This is a review on the emerging field of adoptively transferred engineered T cell based approaches, with an in-depth focus on chimeric antigen receptors (CAR) targeting multiple myeloma. The recent results from CAR T cells targeting B cell maturation antigen are encouraging but eventual resistance to the CAR T cell therapies remain problematic. With newer approaches in therapies for multiple myeloma, the role of transplantation is evolved to form a platform for T cell therapies.

Donor T-cell responses and disease progression patterns of multiple myeloma

Donor T-cells transferred after allogeneic stem cell transplantation (alloSCT) can result in long-term disease control in myeloma by the graft-versus-myeloma (GvM) effect. However, T-cell therapy may show differential effectiveness against bone marrow (BM) infiltration and focal myeloma lesions resulting in different control and progression patterns. Outcomes of 43 myeloma patients who underwent T-cell-depleted alloSCT with scheduled donor lymphocyte infusion (DLI) were analyzed with respect to diffuse BM infiltration and focal progression. For comparison, 12 patients for whom a donor search was started but no alloSCT was performed, were analyzed. After DLI, complete disappearance of myeloma cells in BM occurred in 86% of evaluable patients. The probabilities of BM progression-free survival (PFS) at 2 years after start of donor search, alloSCT and DLI, were 17% (95% confidence interval 0-38%), 51% (36-66%), and 62% (44-80%) respectively. In contrast, the probabilities of focal PFS at 2 years after start of donor search, alloSCT and DLI, were 17% (0-38%), 30% (17-44%) and 28% (11-44%), respectively. Donor-derived T-cell responses effectively reduce BM infiltration, but not focal progression in myeloma, illustrating potent immunological responses in BM with only limited effect of T-cells on focal lesions.

Possible Impact of Cytomegalovirus-Specific CD8+ T Cells on Immune Reconstitution and Conversion to Complete Donor Chimerism after Allogeneic Stem Cell Transplantation

Complete donor chimerism is strongly associated with complete remission after allogeneic stem cell transplantation (allo-SCT) in patients with hematologic malignancies. Donor-derived allo-immune responses eliminate the residual host hematopoiesis and thereby mediate the conversion to complete donor chimerism. Recently, cytomegalovirus (CMV) reactivation was described to enhance overall T cell reconstitution, to increase graft-versus-host disease incidence, and to reduce the leukemia relapse risk. However, the link between CMV and allo-immune responses is still unclear. Here, we studied the relationship between CMV-specific immunity, overall T cell reconstitution, and residual host chimerism in 106 CMV-seropositive patients transplanted after reduced-intensity conditioning including antithymocyte globulin. In accordance with previous reports, the recovery of CMV-specific cytotoxic T cells (CMV-CTLs) was more frequent in CMV-seropositive recipients (R) transplanted from CMV-seropositive than from seronegative donors (D). However, once CMV-CTLs were detectable, the reconstitution of CMV-specific CTLs was comparable in CMV R+/D- and R+/D+ patients. CD3⁺ and CD8⁺ T cell reconstitution was significantly faster in patients with CMV-CTLs than in patients without CMV-CTLs both in the CMV R+/D- and R+/D+ setting. Moreover, CMV-CTL numbers correlated with CD3⁺ and CD8⁺ T cell numbers in both settings. Finally, presence of CMV-CTLs was associated with low host chimerism levels 3 months after allo-SCT. In conclusion, our data provide a first indication that CMV-CTLs in CMV-seropositive patients might trigger the reconstitution of T cells and allo-immune responses reflected by the conversion to complete donor chimerism.

Evaluation of TCR repertoire diversity in patients after hematopoietic stem cell transplantation

T-cell receptor (TCR) repertoire analyses have been widely used to identify T cell populations of interest in cancer and autoimmunity and for characterizing immune repertoire reconstitution after hematopoietic stem cell transplantation (HSCT). Several decades of development and progress have led to the use of techniques for evaluating TCR repertoires in a more comprehensive, unbiased and fast manner, and the mechanisms of T cell immune reconstitution after HSCT and the new approaches used for recovering T cell repertoire diversity post HSCT have been more exhaustively documented to some degree. To better understand and characterize this progress, here we review recent studies on TCR repertoire diversity recovery in patients with leukemia and autoimmune disease who have received HSCT, impact factors and improvements in approaches for TCR repertoire recovery after HSCT.

Immune escape from NY-ESO-1-specific T-cell therapy via loss of heterozygosity in the MHC

Adoptive immunotherapy of tumors with T cells specific for the cancer-testis antigen NY-ESO-1 has shown great promise in preclinical models and in early stage clinical trials. Tumor persistence or recurrence after NY-ESO-1-specific therapy occurs, however, and the mechanisms of recurrence remain poorly defined. In a murine xenograft model of NY-ESO-1⁺ multiple myeloma, we observed tumor recurrence after adoptive transfer of CD8⁺ T cells genetically redirected to the prototypic NY-ESO-1_157-165 peptide presented by HLA-A*02:01. Analysis of the myeloma cells that had escaped from T cell control revealed intact expression of NY-ESO-1 and B2M, but selective, complete loss of HLA-A*02:01 expression from the cell surface. Loss of heterozygosity in the Major Histocompatibility Complex (MHC) involving the HLA-A locus was identified in the tumor cells, and further analysis revealed selective loss of the allele encoding HLA-A*02:01. Although loss of heterozygosity involving the MHC has not been described in myeloma patients with persistent or recurrent disease after immune therapies such as allogeneic hematopoietic cell transplantation (HCT), it has been described in patients with acute myelogenous leukemia who relapsed after allogeneic HCT. These results suggest that MHC loss should be evaluated in patients with myeloma and other cancers who relapse after adoptive NY-ESO-1-specific T cell therapy.

Host lymphocyte depletion as a strategy to facilitate early full donor chimerism after reduced-intensity allogeneic stem cell transplantation

Reduced-intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (RIC-alloHSCT) is associated with lower toxicity but higher rates of prolonged mixed chimerism than myeloablative conditioning. Decreased pretransplantation host T cell numbers are associated with less graft rejection and early full donor chimerism. To compensate for variability in pretransplantation host lymphocyte numbers and facilitate the achievement of rapid full donor chimerism, we tested a strategy of targeted lymphocyte depletion (TLD) using chemotherapy at conventional doses to provide cytoreduction and lymphocyte depletion before RIC-alloHSCT. In our study, 111 patients with advanced hematologic malignancies received 1 to 3 cycles of conventional-dose chemotherapy to reduce circulating lymphocytes to a predetermined level. Patients then underwent RIC-alloHSCT from HLA-matched siblings. Patients received a median of 2 cycles of TLD chemotherapy, resulting in a median 71% decline in CD4(+) count. All patients engrafted; there were no late graft failures. By day +14, median CD3(+) chimerism was 99% donor and was significantly associated with lower post-TLD CD4(+) counts (P = .012). One- and 5-year treatment-related mortality were 15% and 21%, respectively. At 1-year follow-up, 66% of patients had achieved complete remission (CR) of which 92% were not in CR at the time of transplantation. Overall survival at 1 and 5 years post transplantation were 66% and 47%, respectively.

Donor CD3(+) lymphocyte infusion after reduced intensity conditioning allogeneic stem cell transplantation: single-center experience

Donor lymphocyte infusions (DLI) can induce remission in patients with hematologic malignancies who relapse after allogeneic stem cell transplantation. However, graft-vs-host disease (GVHD) remains a major complication of this strategy. We have used escalating doses of DLI for many years, and wanted to assess the risk factors for GVHD and transplant-related mortality as well as disease outcomes according to the reason for DLI. We analyzed 65 patients who received a total of 111 DLI for different reasons and at different intervals after transplantation. Median number of DLI was 2 (range, 1-4), median interval between transplantation and DLI was 9 months (range, 1-41 months) and median number of infused CD3(+) cells/kg recipient body weight was 2.5 × 10(7) (range, 1 × 10(6)-11.8 × 10(7)). Reasons for DLI were relapse or progression in 37 patients (57%), residual disease in 15 patients (23%), and persistence of mixed chimerism in 13 patients (20%). Seven patients (11%) developed acute GVHD grade II to IV and 5 patients (8%) developed extensive chronic GVHD. In univariate analysis, we could identify a transplantation-DLI interval ≤6 months, the dose of DLI (≥1 × 10(7)), and DLI number as predictive factors of GVHD. In multivariate analysis, these results were confirmed only for the transplantation-DLI interval (hazard ratio = 19.48; 2.23-170.34; p = 0.007). Our findings indicate that this form of adoptive immunotherapy is well tolerated and induces a low incidence of GVHD and transplant-related mortality, supporting further investigation as an upfront modality to enhance the graft-vs-tumor response in high-risk patients.

Recipient lymphocyte infusion in MHC-matched bone marrow chimeras induces a limited lymphohematopoietic host-versus-graft reactivity but a significant antileukemic effect mediated by CD8+ T cells and natural killer cells

BACKGROUND

Challenge of MHC-mismatched murine bone marrow chimeras with recipient-type lymphocytes (recipient lymphocyte infusion) produces antileukemic responses in association with rejection of donor chimerism. In contrast, MHC-matched chimeras resist eradication of donor chimerism by recipient lymphocyte infusion. Here, we investigated lymphohematopoietic host-versus-graft reactivity and antileukemic responses in the MHC-matched setting, which is reminiscent of the majority of clinical transplants.

DESIGN AND METHODS

We challenged C3H→AKR radiation chimeras with AKR-type splenocytes (i.e. recipient lymphocyte infusion) and BW5147.3 leukemia cells. We studied the kinetics of chimerism using flowcytometry and the mechanisms involved in antileukemic effects using in vivo antibody-mediated depletion of CD8(+) T and NK cells, and intracellular cytokine staining.

RESULTS

Whereas control chimeras showed progressive evolution towards high-level donor T-cell chimerism, recipient lymphocyte infusion chimeras showed a limited reduction of donor chimerism with delayed onset and long-term preservation of lower-level mixed chimerism. Recipient lymphocyte infusion chimeras nevertheless showed a significant survival benefit after leukemia challenge. In vivo antibody-mediated depletion experiments showed that both CD8(+) T cells and NK cells contribute to the antileukemic effect. Consistent with a role for NK cells, the proportion of IFN-γ producing NK cells in recipient lymphocyte infusion chimeras was significantly higher than in control chimeras.

CONCLUSIONS

In the MHC-matched setting, recipient lymphocyte infusion elicits lymphohematopoietic host-versus-graft reactivity that is limited but sufficient to provide an antileukemic effect, and this is dependent on CD8(+) T cells and NK cells. The data indicate that NK cells are activated as a bystander phenomenon during lymphohematopoietic T-cell alloreactivity and thus support a novel type of NK involvement in anti-tumor responses after post-transplant adoptive cell therapy.

Multiple myeloma patients at peripheral blood stem cell harvest: restricted usage of TCR beta variable families

The immune systems of multiple myeloma patients are suppressed by the disease itself, and this immunosuppression is further enhanced by standard therapies. The aim of our study was to evaluate the effects of initial chemotherapy and a peripheral blood mobilisation regimen on T-cell population diversity. Reverse transcription-polymerase chain reaction (RT-PCR) with a new set of primers, in combination with capillary electrophoresis, was established. The methodology was used to analyse the relative expression of 27 T-cell receptor beta variable gene families (BV families) in multiple myeloma patients undergoing peripheral blood stem cell harvest. We found that the overall BV family usage in these patients was restricted; the relative expression of 10 BV families was significantly depressed in patients compared to healthy donors. These findings demonstrate that the preparative regimen for autologous stem cell transplantation affects the T-cell population in terms of the restriction of its T-cell receptor diversity.

Induction of tumor immunity following allogeneic stem cell transplantation

The curative potential of allogeneic hematopoietic stem cell transplantation (allo-HSCT) for many hematologic malignancies derives in large part from reconstitution of normal donor immunity and the development of a potent graft-versus-leukemia (GVL) immune response capable of rejecting tumor cell in vivo. Elucidation of the mechanisms of GVL by studies of animal models and analysis of clinical data has yielded important insights into how clinically effective tumor immunity is generated following allo-HSCT. These studies have identified NK cells and B cells as well as T cells as important mediators of the GVL response. A variety of antigenic targets of the GVL response have also been identified, and include tumor-associated antigens as well as minor histocompatibility antigens. The principles of effective GVL can now be applied to the development of novel therapies that enhance the therapeutic benefit of allogeneic HSCT while minimizing the toxicities associated with treatment. Moreover, many components of this approach that result in elimination of tumor cells following allogeneic HSCT can potentially be adapted to enhance the effectiveness of tumor immunity in the autologous setting.

Reduced-intensity conditioning regimen using low-dose total body irradiation before allogeneic transplant for hematologic malignancies: Experience from the European Group for Blood and Marrow Transplantation

PURPOSE

The high rate of toxicity is the limitation of myeloblastive regimens before allogeneic transplantation. A reduced intensity regimen can allow engraftment of stem cells and subsequent transfer of immune cells for the induction of a graft-vs.-tumor reaction.

METHODS AND MATERIALS

The data from 130 patients (80 males and 50 females) treated between 1998 and 2003 for various hematologic malignancies were analyzed. The median patient age was 50 years (range, 3-72 years). Allogeneic transplantation using peripheral blood or bone marrow, or both, was performed in 104 (82%), 22 (17%), and 4 (3%) patients, respectively, from HLA identical sibling donors (n = 93, 72%), matched unrelated donors (n = 23, 18%), mismatched related donors (4%), or mismatched unrelated donors (6%). Total body irradiation (TBI) at a dose of 2 Gy delivered in one fraction was given to 101 patients (78%), and a total dose of 4-6 Gy was given in 29 (22%) patients. The median dose rate was 14.3 cGy/min (range, 6-16.4).

RESULTS

After a median follow-up period of 20 months (range, 1-62 months), engraftment was obtained in 122 patients (94%). Acute graft-vs.-host disease of Grade 2 or worse was observed in 37% of patients. Multivariate analysis showed three favorable independent factors for event-free survival: HLA identical sibling donor (p < 0.0001; relative risk [RR], 0.15), complete remission (p < 0.0001; RR, 3.08), and female donor to male patient (p = 0.006; RR 2.43). For relapse, the two favorable prognostic factors were complete remission (p < 0.0001, RR 0.11) and HLA identical sibling donor (p = 0.0007; RR 3.59).

CONCLUSIONS

In this multicenter study, we confirmed high rates of engraftment and chimerism after the reduced intensity regimen. Our results are comparable to those previously reported. Radiation parameters seem to have no impact on outcome. However, the lack of a statistically significant difference in terms of dose rate may have been due, in part, to the small population size in the subgroup analysis.

Allogeneic haematopoietic cell transplantation for multiple myeloma: reducing transplant-related mortality while harnessing the graft-versus-myeloma effect

Allogeneic haematopoietic cell transplantation (allo-HCT) provides effective therapy for patients with various haematological malignancies. In multiple myeloma (MM) this approach can induce response rates in 35-75% of patients. However, the outcome is hampered by high rates of treatment-related mortality (TRM). Reduced intensity conditioning to lower TRM has been successfully applied. The fact that previous clinical reports have documented graft-versus-myeloma (GVM) activity without graft-versus-host disease (GVHD) suggests that at least two distinct immunocompetent cell populations mediating GVHD and/or GVM may exist. Further characterization of effectors after allo-HCT and their targets may help to clarify the immune response that mediates the GVM effect. This review considers the clinical results with myeloablative and reduced intensity conditioning prior to allo-HCT for MM, with emphasis on attempts to prevent GVHD while preserving the GVM effect. Strategies including donor lymphocyte infusions as part of the allogeneic protocol and antigenic targets for GVM effect are reviewed.

Reconstitution of adaptive and innate immunity following allogeneic hematopoietic stem cell transplantation in humans

Allogeneic hematopoietic stem cell transplantation is a potentially curative treatment modality for a number of hematologic malignancies, as well as inherited immunodeficiencies and hemoglobinopathies, and may also have a role in selected acquired autoimmune disorders. The complete or near-complete ablation of host immunity and subsequent establishment of donor-derived immunity that is required for successful engraftment and long-term outcomes provide a major obstacle to such transplantation approaches. A delicate balance exists between the need for the reconstituted donor-derived immunity to provide both protection against pathogenic challenges and graft-versus-malignancy activity, and the potentially harmful expansion of alloreactive T-cell clones mediating GvHD. The search for interventions that would allow more rapid and selective reconstitution of beneficial immune specificities continues to be informed by the development of new tools enabling a more precise dissection of the kinetics of reconstituting populations. This review summarizes more recent data on immune reconstitution following allogeneic transplantation in humans.

CD4+CD25+ Regulatory T Cells in Hematopoietic Stem Cell Transplantation

Allogeneic hematopoietic stem cell transplantation (SCT) is a well-established treatment modality for malignant and nonmalignant hematologic diseases. High-dose radio- and/or chemotherapy eradicate the hematopoietic system of the patient and induce sufficient immunosuppression to enable donor stem cell engraftment. The replacement of the recipient's immune system with that of the donor significantly contributes to the success of this treatment, since donor immune cells facilitate stem cell engraftment, provide protection from infections, and eliminate residual malignant or nonmalignant host hematopoiesis, thereby protecting from disease relapse in patients transplanted for leukemia or lymphoma (graft-versus-leukemia effect, GVL). Mediators of these beneficial effects are mature T cells within the stem cell graft. However, donor T cells can also attack host tissues and induce a life-threatening syndrome called graft-versus-host disease (GVHD). The challenge of allogeneic SCT is to find a balance between beneficial and harmful T cell effects, which at present is only insufficiently achieved by the use of immunosuppressive drugs. In the future, it might be possible to replace or support such medications by using the intrinsic regulatory capacity of the transplanted immune system, as represented by T cell subpopulations with suppressive activity, such as CD4+ CD25+ regulatory T (Treg) cells. In various mouse model systems, these cells have been shown to suppress GVHD while preserving the GVL effect. As the characterization of their human counterparts is rapidly progressing, their application in allogeneic SCT might soon be explored in clinical trials.

Flucloxacillin-induced aplastic anaemia and liver failure

Flucloxacillin is a commonly prescribed semisynthetic penicillinase-resistant penicillin primarily used for the treatment of cutaneous staphylococcal infections. It is well-recognized that flucloxacillin may occasionally result in fatal hepatic injury. We report the case of a 40-year-old woman who developed fulminant hepatic failure and aplastic anaemia following a course of oral flucloxacillin. At the time of transplantation the patient was severely neutropenic. Post-transplant, the patient received single donor leucocyte transfusions, which resulted in a dramatic increase in neutrophil count. The patient was discharged from hospital after 120 days with normal liver function and recovered bone marrow. In this report, we discuss the care of patients with aplastic anaemia in the peritransplant setting.

Nonmyeloablative stem cell transplantation in metastatic renal cell carcinoma: delayed graft-versus-tumor effect is associated with chimerism conversion but transplantation has high toxicity

Seven out of 29 patients with metastatic renal cell carcinoma (RCC) considered eligible for allogeneic stem cell transplantation underwent nonmyeloablative stem cell transplantation (NST) from HLA-identical donors. Conditioning comprised cyclophosphamide, fludarabine and antithymocyte globulin. Prolonged mixed chimerism (MC) after engraftment converted to complete donor chimerism (CC) after infusion of donor lymphocytes and/or graft-versus-host disease (GvHD) in six patients. Five patients developed severe GvHD. Two of seven patients had a delayed tumor response after conversion to CC. After a median follow-up of 10 months (4-24 months), 5/7 patients are alive, one in very good partial remission (PR), one with stable and three with progressive disease. One of the seven patients died from sepsis in PR and 1/7 died from rapid tumor progression after sustained MC. None of the 22 nontransplanted patients responded to further therapies. Survival after 1 year was 59% in transplanted and 66% in nontransplanted patients (n.s.). A pooled data analysis from the literature suggests a graft-versus-tumor effect after transplant in patients with metastatic RCC, which becomes effective after chimerism conversion. Available data demonstrate high nonrelapse mortality in these patients. NST in RCC still has to be regarded as an investigational approach requiring careful patients' selection and longer follow-up within clinical studies.

A class II-restricted cytotoxic T-cell clone recognizes a human minor histocompatibility antigen with a restricted tissue distribution

Following a human leucocyte antigen (HLA)-identical allogeneic stem cell transplantation (allo-SCT), minor histocompatibility antigens (mHags) play an important role in the induction of graft-versus-leukaemia (GvL) and graft-versus-myeloma (GvM). Many mHags show ubiquitous tissue expression and are associated with GvL and graft-versus-host disease. Here we describe a cytotoxic CD4(+) T lymphocyte line and a cytotoxic, CD4(+) T cell clone (CTC), 3AB11, which recognized a tissue-restricted mHag. This CTC was isolated from a multiple myeloma patient with clinical GvM following an HLA-matched allo-SCT. CTC 3AB11 was activated in a HLA-DP*0401 restricted fashion and the antigen was expressed by 27% of HLA-DP*0401 positive Epstein-Barr virus (EBV)-transformed B-cell lines (EBV-B). Tissue distribution analysis of antigen 3AB11 showed it to be expressed by patient-derived EBV-transformed B cell lines (EBVp), the myeloma plasma cell-line UM9 and monocytes. It was weakly expressed by peripheral blood-derived phytohaemagglutinin-induced T-cell blasts and absent on CD40L stimulated peripheral B (CD40L B) cells and stromal cells. The relatively high prevalence of the HLA class II-restricted 3AB11 antigen, together with its apparent haematopoietic-restricted expression, makes it an antigen of interest for cellular immunotherapy.

Outcome of unrelated transplants in patients with multiple myeloma

The outcome of patients with multiple myeloma treated with standard therapy is disappointing, with a historical median survival of 3 years. Although high-dose therapy with autologous stem cell transplant has improved treatment outcomes, cure is unlikely. Allogeneic transplant provides a tumor-free graft and a graft-versus-myeloma effect. However, only a minority of patients has a compatible sibling donor. Unrelated hematopoietic stem cell transplant is another option. We analyzed the outcome of patients who received an unrelated bone marrow transplant facilitated by the National Marrow Donor Program (NMDP). Between 1989 and 2000, 71 patients received a myeloablative unrelated transplant for multiple myeloma; 70 patients consented for this analysis. The median recipient age was 44 years. A total of 31% of patients had received a prior autologous transplant. In all, 91% of patients engrafted. The 3-year cumulative incidence estimate of relapse was 34+/-10%. The incidence of Grade II-IV GVHD was 47%. The Kaplan-Meier estimate for overall survival at 5 years was 9+/-7%. The 100-day treatment-related mortality was 42%. In multivariate analysis, only a male donor was a significant predictor for survival. Better strategies are needed to treat patients with multiple myeloma, perhaps by using less-toxic, nonmyeloablative conditioning regimens.

Long-term persistent lymphopenia in hematopoietic stem cell donors after donation for donor lymphocyte infusion

OBJECTIVES

To analyze the consequences of lymphocyte donations on lymphopoiesis in donors having previously undergone hematopoietic stem cell collection for allogeneic stem cell transplantation.

METHODS

Repeated analysis of leukocyte subsets in the peripheral blood of 76 hematopoietic stem cell donors undergoing lymphocyte donation(s) for DLI.

RESULTS

Grade I/II lymphopenia was present in 22 donors (29%) just before first apheresis for lymphocyte collection, demonstrating that former stem cell donation induced prolonged lymphopenia in a subset of donors. The monocytic lineage was not affected. Older age and history of PBSC harvest constituted 2 independent factors of lymphopenia, but had no influence on monocytopenia. The first apheresis induced lymphopenia in 36 donors (47%) and monocytopenia in 23 donors (39%). Lymphopenia before first apheresis and prior history of PBSC harvest were independent factors of apheresis-induced lymphopenia while those factors had no influence on monocytopenia. A time-dependent decrease in lymphocyte counts was observed in donors undergoing repeated aphereses, resulting in persistent and prolonged lymphopenia in 50% of donors. No persistent monocytopenia over time and aphereses was observed. Kaplan-Meier estimate of the risk to develop persistent lymphopenia after multiple aphereses was 21% +/- 6% at 2 months, 38% +/- 8% at 4 months, and 64% +/- 10% at 12 months. After Cox regression analysis, previous PBSC harvest remained the unique factor associated with the risk for persistent lymphopenia.

CONCLUSIONS

Monitoring the potential long-term effects of repeated aphereses in hematopoietic stem cell donors appears important. Selecting young bone marrow donors for subsequent DLI significantly reduces the risk for acute and prolonged lymphopenias.

How and when should we monitor chimerism after allogeneic stem cell transplantation?

SUMMARY

Chimerism analysis has become an important tool for the peri-transplant surveillance of engraftment. It offers the possibility to realize impending graft rejection and can serve as an indicator for the recurrence of the underlying malignant or nonmalignant disease. Most recently, these investigations have become the basis for treatment intervention, for example, to avoid graft rejection, to maintain engraftment and to treat imminent relapse by pre-emptive immunotherapy. This invited review focuses on the clinical implications of characterization of hematopoietic chimerism in stem cell transplantation.

Addition of treosulfan to a nonmyeloablative conditioning regimen results in enhanced chimerism and immunologic tolerance in an experimental allogeneic bone marrow transplant model

Treosulfan (L-threitol-1,4-bismethanesulfonate) is an alkylating agent with routine clinical application in the treatment of ovarian cancer. In this murine study we show that this drug also has the ability to deplete primitive hematopoietic stem cells in a dose-dependent manner as determined by the cobblestone area-forming cell assay and is similar to its parent compound busulfan. Because busulfan is frequently used as part of the conditioning regimen before stem cell transplantation, we investigated an alternative nonmyeloablative protocol in an allogeneic bone marrow transplantation model in which low-dose treosulfan was added to an immune-suppressive regimen consisting of T cell-depleting antibodies, fludarabine, and thymic irradiation. Although this treatment protocol produced minimal myelosuppression, the addition of treosulfan proved to be important for allowing stable multilineage and mixed chimerism in C57BL/6 recipients of major histocompatibility complex-mismatched B10.A bone marrow without evidence of graft-versus-host disease. Donor lymphocyte infusion performed at 10 weeks after bone marrow transplantation had the effect of transforming the state of mixed chimerism to full donor-type cells, again without evidence of graft-versus-host disease. Donor-specific immunologic tolerance in the mixed chimeric animals was indicated by the acceptance of donor-type and rejection of third-party skin grafts. Thus, low-dose treosulfan may be considered as a useful component of a truly nonmyeloablative conditioning protocol in providing for mixed hematopoietic chimerism and, consequently, in establishing a platform for adoptive immunotherapy.

Molecular Analysis of T-Cell Repertoire in Patients with Graft-Versus-Host Disease after Allogeneic Stem Cell Transplantation

Complementarity-determining region (CDR3) size spectratyping has often been used to analyze the clonal expansion of T-cells. CDR3 size spectratyping has been useful in the analysis of the oligoclonal expansion of T-cells in virus infection, graft-versus-leukemia effect (GVL), graft-versus-host disease (GVHD), and immune reconstitution of T-cells after allogeneic stem cell transplantation (allo-SCT). We analyzed 26 T cell receptor (TCR)-beta-chain subfamilies (VB) in 25 patients who underwent allo-SCT. Fifteen of these patients developed acute GVHD (aGVHD). Many TCR-VB were skewed in the early stage. In these TCR-VB subfamilies, VB6 was most often skewed at the time of skin aGVHD. We then analyzed the average score of the complexity of 26 TCR-VB spectratypings in patients with or without cGVHD. The patients who developed chronic GVHD (cGVHD) had a lower average score of TCR-VB complexity than that of patients without cGVHD (P = 0.010). In particular. the patients who developed the quiescent type and de novo type of cGVHD from 4 months after allo- SCT had a lower average score of TCR-VB complexity at 3 months than that of the patients who had no cGVHD (P = 0.0055). These results suggest that we might be able to consider a possible development of cGVHD by analyzing TCR-VB spectratyping after allo-SCT.

Adoptive immunotherapy with donor lymphocyte infusions after allogeneic hematopoietic cell transplantation following nonmyeloablative conditioning

This study retrospectively analyzed data from 446 patients given hematopoietic cell transplants from HLA-matched related or unrelated donors after conditioning with 2 Gy total body irradiation with or without fludarabine and postgrafting immunosuppression with mycophenolate mofetil and cyclosporine following grafting. Fifty-three of 446 patients received donor lymphocyte infusion (DLI) with a median CD3 dose of 1 × 107 cells/kg. Their diagnoses included myelodysplastic syndrome (n = 10), acute leukemia (n = 10), chronic leukemia (n = 11), multiple myeloma (n = 9), lymphoma (n = 9), and solid tumors (n = 4). Patients received DLI for persistent disease (n = 8), disease relapse (n = 17), progressive disease (n = 12), low donor chimerism with disease (n = 11), or low chimerism with disease remission (n = 5). Seventeen of the 53 patients (32%) are alive with a median follow-up of 30 months; 5 are in complete remission (CR), 2 are in partial remission (PR), and 10 have stable or progressive disease. Nine of 53 patients (17%) developed grades II to IV acute graft-versus-host disease. Of 48 patients receiving DLI for treatment of disease, 7 achieved CR and 5 PR, with an overall response rate of 25%. Six of 16 patients who received DLI for chimerism had increases in donor chimerism leading to sustained engraftment, whereas 10 eventually rejected their grafts. In conclusion, DLI is a potential treatment strategy, with acceptable toxicity, for patients with persistent, relapsed, or progressive disease after nonmyeloablative hematopoietic cell transplantation.

Hematopoietic cell transplantation: five decades of progress

During the past 50 years, the role of allogeneic hematopoietic cell transplantation (HCT) has changed from a desperate therapeutic maneuver plagued by apparently insurmountable complications to a curative treatment modality for thousands of patients with hematologic diseases. Now, cure rates following human leukocyte antigen (HLA) allogeneic HCT with matched siblings exceed 85% for some otherwise lethal diseases, such as chronic myeloid leukemia, aplastic anemia, or thalassemia. In addition, the recent development of non-myeloablative conditioning and stem cell transplantation has opened the way to include elderly patients with a wide variety of hematologic malignancies. Further progress in adoptive transfer of T cell populations with relative tumor specificity would make the transplant procedure more effective and would extend the use of allogeneic HCT for treatment of non-hematopoietic malignancies.

Low T-cell chimerism is not followed by graft rejection after nonmyeloablative stem cell transplantation (NMSCT) with CD34-selected PBSC

We investigate the feasibility of CD34-selected peripheral blood stem cell (PBSC) transplantation followed by pre-emptive CD8-depleted donor lymphocyte infusions (DLI) after a minimal conditioning regimen. Six patients with advanced hematological malignancies ineligible for a conventional myeloablative transplant (n=5) or metastatic renal cell carcinoma (n=1), and with an HLA-identical (n=4) or alternative (n=2) donor were included. The nonmyeloablative conditioning regimen consisted in 2 Gy TBI alone (n=4), 2 Gy TBI and fludarabine (RCC patient, n=1) or cyclophosphamide and fludarabine (patient who had previously received 12 Gy TBI, n=1). Post transplant immunosuppression was carried out with cyclosporin (CyA) and mycophenolate mofetil (MMF). Initial engraftment was achieved in all patients. One out of six patients (17%) experienced grade > or =2 acute GVHD only after abrupt cyclosporin discontinuation and alpha interferon therapy for life-threatening tumor progression. T-cell chimerism was 23% (19-30) on day 28, 32% (10-35) on day 100, 78% (49-95) on day 180 and 99.5% (99-100) on day 365. Three out of four patients who had measurable disease before the transplant experienced a complete response. We conclude that CD34-selected NMSCT followed by CD8-depleted DLI is feasible and preserves engraftment and apparently also the graft-versus-leukemia (GVL) effect. Further studies are needed to confirm this encouraging preliminary report.

Molecular assessment of erythroid lineage chimerism following nonmyeloablative allogeneic stem cell transplantation

OBJECTIVE

Nonmyeloablative conditioning regimens for allogeneic stem cell transplantation are now commonly used in the treatment of patients with hematologic malignancies. Since this treatment often results in the establishment of mixed hematopoietic chimerism, this approach may also prove to be useful in the treatment of nonmalignant disorders, such as sickle cell disease and thalassemia major. To apply this approach to these diseases, it will be necessary to determine the levels of donor erythropoiesis required to correct hemolysis and ameliorate disease symptoms. Current methods for measuring hematopoietic chimerism are based on DNA polymorphisms that distinguish recipient from donor. These methods accurately measure donor leukocyte engraftment but do not quantify the relative contributions of recipient and donor erythropoiesis following transplant.

METHODS

To specifically measure erythroid-lineage chimerism, we used pyrosequencing of the sickle cell mutation to quantify the relative levels of normal and sickle beta-globin mRNA in patient samples. Results of beta-globin RNA chimerism were compared to assessment of beta-globin DNA chimerism as well as analysis of short tandem repeat (STR) polymorphisms, cytogenetics, and hemoglobin electrophoresis.

RESULTS

Donor engraftment was measured in two adult patients following nonmyeloablative stem cell transplant for sickle cell disease. In Patient 1, 25 to 30% of peripheral leukocytes were donor derived after day 41. In contrast, more than 55% of peripheral blood beta-globin mRNA was of donor origin, and these results correlated with posttransplant clinical improvement. Patient 2 achieved 40 to 50% donor leukocyte engraftment from day 33 onward. This was associated with 70 to 100% peripheral blood donor beta-globin mRNA.

CONCLUSIONS

These studies demonstrate that relatively low levels of donor leukocyte engraftment can be associated with higher levels of donor erythropoiesis and with significant clinical improvement. Pyrosequencing of lineage-specific mRNA directly measures functional reconstitution of donor cells and provides valuable information that can affect clinical decisions in patients with nonmalignant diseases following allogeneic transplant.

Reduced-intensity transplantation with in vivo T-cell depletion and adjuvant dose-escalating donor lymphocyte infusions for chemotherapy-sensitive myeloma: limited efficacy of graft-versus-tumor activity

Reduced-intensity conditioning regimens allow application of allogeneic stem cell transplantation to greater numbers of patients with myeloma by reducing transplantation-related mortality. We prospectively evaluated the role of an approach incorporating in vivo T-cell depletion and subsequent adjuvant donor lymphocyte infusions (DLIs) as part of front-line therapy for chemotherapy-sensitive multiple myeloma. Twenty patients with HLA-matched related (n = 12) or unrelated (n = 8) donors entered the study. None had previously undergone autologous transplantation. Acute graft-versus-host disease (GVHD) following transplantation was minimal (3 grade II and no grade III or IV). Nonrelapse mortality rate was relatively low (15%) compared with conventional myeloablative allogeneic transplantation series, although it remained significantly higher than in the autologous setting. Disease responses by 6 months posttransplantation were modest (2 in complete remission, 4 in partial remission, 2 were minimally responsive, 6 had no change, 3 had progressive disease, and 3 were not evaluable). Fourteen patients received escalating-dose DLI for residual/progressive disease. Three developed acute GVHD and 2 developed limited chronic GVHD. Seven demonstrated further disease responses, which appeared to be more common in those developing GVHD (5 of 5 versus 2 of 9; P =.02). All responses were associated with conversion from mixed to full donor T-cell chimerism. Response durations were disappointing (5 <12 months) and progression often occurred despite persisting full donor chimerism. Two-year estimated overall survival and current progression-free survival rates (intention to treat with DLI from 6 months) were 71% and 30%, respectively. The current approach incorporating T-cell depletion appears excessively immunosuppressive despite attempts to restore immune function with DLI. Dose escalation failed to allow convincing dissociation of graft-versus-myeloma from GVHD. Attempts to hasten immune reconstitution and to focus and amplify appropriate components of allogeneic T-cell responses will be required to increase complete remission rates and response durations.

Factors predicting response and graft-versus-host disease after donor lymphocyte infusions: a study on 593 infusions

In the present study, we analyze factors predicting graft-versus-host disease (GvHD) and response after donor lymphocyte infusions (DLI). A total of 100 patients received 593 DLI between June 1990 and December 2000 in a bulk dose (n=14) or in escalating dose infusions (n=86). Patients were analyzed after stratification for type of relapse: (1). molecular relapse (n=6), (2). cytogenetic relapse (n=20), (3). chronic phase of chronic myeloid leukemia (CML) or complete remission of other disease post chemotherapy (n=24), (4). CML in accelerated/blastic phase (n=14), (5). resistant disease not responding to chemotherapy (n=36). The proportion of responders to DLI in these five groups was 100, 90, 75, 36 and 0% (P<0.0001). Factors predicting response by multivariate analysis were type of relapse (P<0.0001), post-DLI GvHD (P=0.005), pancytopenia (P=0.008), and a diagnosis of CML (P=0.04). Acute GvHD (grades II-IV) occurred in 21 patients (21%), and correlated in multivariate analysis with pancytopenia and less than four DLI. Other predictors of GvHD were the number of CD3+cells/infusion and serum levels of gamma-glutamyl transferase (gammaGT). The actuarial probability of treatment-related mortality was 9% for HLA identical siblings and 44% for alternative donor transplants (P=0.006). Response to DLI is predicted by tumor burden and is associated with GvHD and pancytopenia.

Minor histocompatibility antigens as targets of graft-versus-leukemia reactions

The main advantage of allogeneic stem cell transplantation over autologous stem cell transplantation for hematologic malignancies is the ability to perform cellular immunotherapy using donor-derived immune effector cells after transplantation. In HLA-matched allogeneic stem cell transplantation, the beneficial graft-versus-leukemia effect of donor lymphocytes appears to be caused mainly by alloreactive T cells that are capable of recognizing minor histocompatibility antigens on the malignant cell population from the patient. The tissue distribution of minor histocompatibility antigens probably determines the clinical result of T-cell responses against these antigens. Whereas T cells recognizing broadly expressed antigens cause not only graft-versus-leukemia but also graft-versus-host disease, T cells recognizing minor histocompatibility antigens specifically expressed on hematopoietic cells may mainly eliminate hematopoietic cells from the recipient, including the malignant cells, without affecting donor hematopoiesis or normal nonhematopoietic tissues. Graft-versus-host disease may still occur because of the induction of inflammatory responses against hematopoietic cells in the tissues. Vaccination of patients after transplantation or vaccination of stem cell donors before transplantation using minor histocompatibility antigen-specific peptides, production of minor histocompatibility antigen-specific T cells, and redirection of T-cell specificity by gene transfer of T-cell receptors may be strategies to eradicate specifically the malignant cells after allogeneic stem cell transplantation.

Allogeneic stem cell transplantation for multiple myeloma

The sensitivity of myeloma cells to high dose chemotherapy has led to the use of allogeneic hematopoietic stem cell transplantation (HSCT) as a therapeutic modality in this disease. In addition to providing more effective chemotherapy, the transplantation of allogeneic stem cells also initiates the development of an allogeneic immune response directed against residual myeloma cells. Direct evidence for a graft vs. myeloma (GVM) effect is provided by the ability of donor lymphocyte infusion (DLI) to induce significant responses in 30-50% of patients with myeloma who have relapsed after allogeneic HSCT. Nevertheless, allogeneic stem cell transplantation is also associated with a high incidence of transplant related toxicities, including regimen-related toxicities, graft vs. host disease (GVHD) and opportunistic infections. DLI has been shown to enhance immune reconstitution after allogeneic HSCT in addition to inducing a GVM response. Current efforts are directed at reducing the toxicities associated with allogeneic HSCT, identification of the target antigens of GVM and the development of new strategies to selectively enhance the immune response to myeloma cells.

Crucial role of timing of donor lymphocyte infusion in generating dissociated graft-versus-host and graft-versus-leukemia responses in mice receiving allogeneic bone marrow transplants

A murine model of minor histocompatibility antigen-mismatched bone marrow transplantation (BMT) was used to study the role of timing of donor lymphocyte infusion (DLI) in eliciting graft-versus-host (GVH) and graft-versus-leukemia (GVL) reactivity. We gave DLI at weeks 3 and 12 after BMT and related its ability to induce a GVL effect with (1) evolution of T cell chimeric status and (2) the extent to which DLI could elicit lymphohematopoietic GVH (LHGVH) reactivity. All mice remained free of GVH disease, but only week 3 DLI chimeras exhibited a significant GVL response when challenged with host-type leukemia cells. In these week 3 DLI chimeras, host-reactive T cells were found to proliferate in vivo (5- [and-6]-carboxyfluorescein diacetate, succinimidyl esther [CFSE]-labeled DLI inocula, TCR-Vbeta6(+) T-cell frequency) and T-cell chimerism rapidly converted from mixed into complete donor type, indicating the occurrence of LHGVH reactivity. In week 12 chimeras, DLI elicited none of the activities noted at week 3. Yet, in both instances, splenocytes, recovered following DLI, generated an equally strong antihost proliferative response in a mixed lymphocyte reaction, thereby arguing against a decisive role of regulatory cells. The lack of in vivo LHGVH reactivity after week 12 DLI was associated with a substantially increased level of pre-existing host-type T-cell chimerism. We conclude that elicitation of a GVL effect may require LHGVH reactivity and that the reason why timing of DLI was critical for obtaining LHGVH reactivity and the desired GVL effect may lie in the evolution of chimeric status. A possible direct involvement of residual host-type antigen-presenting cells in eliciting LHGVH reactivity after DLI should be studied using models that allow chimerism analysis in non-T-cell lineages.

Novel biologically based therapeutic strategies in myeloma

Multiple myeloma remains incurable despite advances in conventional chemotherapy and wider applicability of high dose chemotherapy with single and/or tandem autologous peripheral blood stem cell transplantation. Although a complete remission rate of 41% and an event-free survival of 43 months have been reported after tandem transplantation, it is highly unlikely that further improvements in the outcome of multiple myeloma will be achieved by escalating cytotoxic chemotherapy alone. Novel biologically based therapies are therefore urgently required. Targeted therapeutic approaches based on: identification of genetic abnormalities in malignant plasma cells; interrupting growth of myeloma cells; triggering apoptotic signaling cascades in tumor cells; modulating growth and survival of multiple myeloma cells in the bone marrow microenvironment, i.e. angiogenesis and cytokine networks; enhancing allogeneic and autologous antimyeloma immunity; and characterizing newer myeloma antigens for serotherapy are under development. These therapies offer great promise, used alone/or in combination with conventional treatment approaches, to improve the outcome in this disease in newly diagnosed/refractory or relapsed patients with multiple myeloma.

Analysis of T-cell repertoire and mixed chimaerism in a patient with aplastic anaemia after allogeneic bone marrow transplantation

We analysed 26 T-cell receptor (TCR) beta chain subfamilies (VB) of a patient with aplastic anaemia (AA) who underwent allogeneic bone marrow transplantation (allo-BMT). The patient developed pancytopenia at d 80. The patient's T cells were skewed in 10 of 26 TCR-VB on d 83. These TCR-VB, especially VB15, which were almost entirely CD8-positive cells, were skewed throughout her clinical course. Chimaerism analysis of the CD8-positive cells indicated that they were of recipient origin. Therefore, some immune responses induced by the recipient CD8-positive T cells had an important role in pancytopenia in AA patients after allo-BMT.

Immunologic effects of prophylactic donor lymphocyte infusion after allogeneic marrow transplantation for multiple myeloma

Reconstitution of T-cell immunity after bone marrow transplantation (BMT) is often delayed, resulting in a prolonged period of immunodeficiency. Donor lymphocyte infusion (DLI) has been used to enhance graft-versus-leukemia activity after BMT, but the effects of DLI on immune reconstitution have not been established. We studied 9 patients with multiple myeloma who received myeloablative therapy and T-cell-depleted allogeneic BMT followed 6 months later by infusion of lymphocytes from the same donor. DLI consisted of 3 x 10(7) CD4(+) donor T cells per kilogram obtained after in vitro depletion of CD8(+) cells. Cell surface phenotype of peripheral lymphocytes, T-cell receptor (TCR) V beta repertoire, TCR rearrangement excision circles (TRECs), and hematopoietic chimerism were studied in the first 6 months after BMT and for 1 year after DLI. These studies were also performed in 7 patients who received similar myeloablative therapy and BMT but without DLI. Phenotypic reconstitution of T and natural killer cells was similar in both groups, but patients who received CD4(+) DLI developed increased numbers of CD20(+) B cells. TCR V beta repertoire complexity was decreased at 3 and 6 months after BMT but improved more rapidly in patients who received DLI (P =.01). CD4(+) DLI was also associated with increased numbers of TRECs in CD3(+) T cells (P <.001) and with conversion to complete donor hematopoiesis (P =.05). These results provide evidence that prophylactic infusion of CD4(+) donor lymphocytes 6 months after BMT enhances reconstitution of donor T cells and conversion to donor hematopoiesis as well as promoting antitumor immunity.

Donor lymphocyte infusions to treat hematologic malignancies in relapse after allogeneic blood or marrow transplantation

BACKGROUND

Patients with hematologic malignancies in relapse after allogeneic bone marrow transplantation can be treated by infusing leukocytes from the original stem cell donor.

METHODS

The published literature on donor lymphocyte infusion (DLI) was reviewed.

RESULTS

DLI induces complete remissions in the majority of patients with chronic myeloid leukemia (CML) in early-stage relapse and in less than 30% of patients with relapsed acute leukemia, myelodysplasia, and multiple myeloma. DLI-induced remissions of chronic phase CML are durable, but as many as half of patients with other diseases ultimately relapse. Complications of DLI include acute and chronic graft-vs-host disease (GVHD) and aplasia, which induce profound immunosuppression and susceptibility to opportunistic infections. There is a strong correlation of GVHD and disease response.

CONCLUSIONS

Novel methods of augmenting the antitumor efficacy of DLI and of dissociating the graft-vs-leukemia effect from GVHD are needed. These studies will require an improved understanding of the cellular and molecular mechanisms of alloreactivity and the development of novel agents to control the nature and intensity of the alloimmune response.

Exploiting graft-versus-tumour responses using donor leukocyte infusions

Allogeneic stem cell transplantation (SCT) has become the treatment of choice for some patients with haematological malignancies, allowing dose escalation of chemo-radiotherapy beyond the limits imposed by bone marrow toxicity. However, it is now apparent that dose escalation alone does not eradicate the malignancy in many cases and that an associated immune-mediated graft-versus-malignancy effect may be equally important. Its presence is supported by the following observations: anecdotal reports that patients with relapsed leukaemia following SCT may re-enter remission after withdrawal of immunosuppressive drugs; the lower risk of relapse associated with the development of graft-versus-host-disease (GVHD); and an increased risk of relapse in patients receiving syngeneic transplants or T-cell depleted allogeneic marrow grafts. More directly compelling evidence has been provided by the efficacy of donor lymphocyte infusions, particularly for relapsed chronic-phase CML. Issues that remain to be resolved include the precise nature of the effector cells and their target antigens, the best strategies for separating graft-versus-malignancy from GVHD, the role of adjuvant chemotherapy/cytokines, and the role of non-myeloablative transplantation.

Cellular therapy: donor lymphocyte infusion

The dose escalation of chemoradiotherapy that is achievable with stem cell transplantation is often insufficient to eradicate malignancy, and an associated immune-mediated graft-versus-malignancy effect may be equally important for many diseases. The most directly compelling evidence for its presence is the efficacy of donor lymphocyte infusions in generating anti-tumor responses, particularly for relapsed chronic-phase chronic myeloid leukemia. Response rates and durability appear lower with myeloma and acute myeloid leukemia and myelodysplasia syndrome, and minimal with acute lymphoblastic leukemia. There is relatively little data on indolent lymphoid malignancies. Issues that remain to be resolved include the precise nature of the effector cells and their target antigens, the best strategies for separating graft-versus-malignancy from graft-versus-host disease (GVHD) and their effect on the durability of responses, and the role of adjuvant chemotherapy/cytokines. Similar issues surround routine combination with nonmyeloablative transplantation protocols and preliminary data suggests that GVHD may continue to provide a major obstacle.

Recent publications in hematological oncology

In order to keep subscribers up-to-date with the latest developments in their field, John Wiley & Sons are providing a current awareness service in each issue of the journal. The bibliography contains newly published material in the field of hematological oncology. Each bibliography is divided into 14 sections: 1 Books, Reviews & Symposia; 2 General; Leukemias: 3 Lymphoblastic; 4 Myeloid & Myelodysplastic Syndromes; 5 Chronic; 6 Others; Lymphomas: 7 Hodgkin's; 8 Non-Hodgkin's; 9 Plasmacytomas/Multiple Myelomas; 10 Others; 11 Bone Marrow Transplantation; 12 Cytokines; 13 Diagnosis; 14 Cytogenetics. Within each section, articles are listed in alphabetical order with respect to author. If, in the preceding period, no publications are located relevant to any one of these headings, that section will be omitted.

Targeted therapy for multiple myeloma

Multiple myeloma (MM) remains incurable with conventional treatment approaches, and novel biologically based therapies are therefore urgently needed. Targeted therapies are either under development or already undergoing clinical evaluation predicated upon: identifying genetic abnormalities in myeloma cells to enhance chemoradiosensitivity; interrupting growth or triggering apoptotic signaling cascades in tumor cells; treating both the tumor cell and its microenvironment; enhancing allogeneic and autologous antimyeloma immunity; and characterizing new myeloma antigens for serotherapy. These therapies, alone or in combination with conventional treatments, offer great promise to improve the outcome for patients with MM.

Nonablative allogeneic hematopoietic stem cell transplantation

During the past few years there has been an explosion of knowledge in nonablative allogeneic stem cell transplantation. This approach to transplantation relies more on the creation of "immunologic space" for engraftment rather than the more traditional approach of creating "physical space" by the application of either intensive radiation or chemical therapy. Nonablative allogeneic stem cell transplantation holds the promise of allowing powerful alloimmune responses to eradicate disease processes while minimizing the initial treatment-related morbidity and mortality, and it appears to be the necessary enabling platform by which to apply allogeneic cellular therapy. Intuitively, this approach should broaden the eligibility for potentially curative allogeneic transplantation in various disease categories, reduce initial hospitalization costs, and at the same time have a positive impact on quality of life. We review the current published data relating to this approach including the underlying principles, the preparative regimen, disease indications, preliminary results in hematologic and solid malignancies, and certain correlative immunologic evaluations.

Multiple Myeloma: New Insights and Therapeutic Approaches

This review discusses the evolution of novel diagnostic and treatment strategies for multiple myeloma based upon increased understanding of basic disease pathogenesis. Although myeloma has remained an incurable illness to date, these new developments will derive treatments to improve outcome and achieve eventual cure.

In Section I, Dr. Kyle reviews the results of current therapy for multiple myeloma, including high dose therapy and stem cell transplantation which have proven to achieve improved response rates, event-free, and overall survival. Supportive therapy, such as erythropoietin to treat disease-related anemia, and methods of prophylaxis against infection, which both lessen toxicities of treatment and improve quality of life for patients, are also addressed.

In Section II, Dr. Dalton with Drs. Landowski, Shain, Jove and Hazlehurst discusses mechanisms of drug resistance in myeloma, with emphasis on novel treatment approaches to prevent development of drug resistance and to overcome drug resistance. Laboratory studies delineating mechanisms whereby myeloma cells resist drug-induced apoptosis provide the framework for related treatment protocols for patients with refractory disease.

In Section III, Dr. Berenson reviews the management of complications in bone, which occur in the majority of patients with myeloma and are the major cause of decreased quality of life. New insights into the mediators of bone resorption and new bone formation in the marrow milieu have already derived effective bisphosphonate therapy. These drugs not only reduce bone complications and related pain, thereby improving quality of life, but also may have intrinsic anti-tumor activity by virtue of inducing tumor cell adherence to marrow, reducing interleukin-6 secretion, inducing tumor cell apoptosis, or inhibiting angiogenesis.

In the last section, Dr. Anderson explores the potential for future therapies which offer great promise to improve patient outcomes. First, drugs which alter the marrow microenvironment include thalidomide and its derivative immunomodulatory drugs, which act directly on tumor cells to induce apoptosis or G1 growth arrest, alter tumor cell adhesion to marrow stroma, inhibit angiogenesis, and trigger a cellular anti-tumor response. The proteasome inhibitors both act directly on tumor cells and also inhibit the transcription factor NFκB-dependent upregulation of IL-6 secretion triggered by tumor cell adhesion. Second, delineation of both growth and apoptotic pathways has derived novel treatment strategies. Third, the preclinical basis and early clinical trial results using vaccination and adoptive immunotherapy to harness autoimmune and alloimmune anti-myeloma responses are presented. This review sets the stage for an evolving new biologically based treatment paradigm in myeloma targeting both the tumor and its microenvironment to improve outcome and achieve eventual cure.

Multiple Myeloma: New Insights and Therapeutic Approaches

This review discusses the evolution of novel diagnostic and treatment strategies for multiple myeloma based upon increased understanding of basic disease pathogenesis. Although myeloma has remained an incurable illness to date, these new developments will derive treatments to improve outcome and achieve eventual cure.

In Section I, Dr. Kyle reviews the results of current therapy for multiple myeloma, including high dose therapy and stem cell transplantation which have proven to achieve improved response rates, event-free, and overall survival. Supportive therapy, such as erythropoietin to treat disease-related anemia, and methods of prophylaxis against infection, which both lessen toxicities of treatment and improve quality of life for patients, are also addressed.

In Section II, Dr. Dalton with Drs. Landowski, Shain, Jove and Hazlehurst discusses mechanisms of drug resistance in myeloma, with emphasis on novel treatment approaches to prevent development of drug resistance and to overcome drug resistance. Laboratory studies delineating mechanisms whereby myeloma cells resist drug-induced apoptosis provide the framework for related treatment protocols for patients with refractory disease.

In Section III, Dr. Berenson reviews the management of complications in bone, which occur in the majority of patients with myeloma and are the major cause of decreased quality of life. New insights into the mediators of bone resorption and new bone formation in the marrow milieu have already derived effective bisphosphonate therapy. These drugs not only reduce bone complications and related pain, thereby improving quality of life, but also may have intrinsic anti-tumor activity by virtue of inducing tumor cell adherence to marrow, reducing interleukin-6 secretion, inducing tumor cell apoptosis, or inhibiting angiogenesis.

In the last section, Dr. Anderson explores the potential for future therapies which offer great promise to improve patient outcomes. First, drugs which alter the marrow microenvironment include thalidomide and its derivative immunomodulatory drugs, which act directly on tumor cells to induce apoptosis or G1 growth arrest, alter tumor cell adhesion to marrow stroma, inhibit angiogenesis, and trigger a cellular anti-tumor response. The proteasome inhibitors both act directly on tumor cells and also inhibit the transcription factor NFκB-dependent upregulation of IL-6 secretion triggered by tumor cell adhesion. Second, delineation of both growth and apoptotic pathways has derived novel treatment strategies. Third, the preclinical basis and early clinical trial results using vaccination and adoptive immunotherapy to harness autoimmune and alloimmune anti-myeloma responses are presented. This review sets the stage for an evolving new biologically based treatment paradigm in myeloma targeting both the tumor and its microenvironment to improve outcome and achieve eventual cure.