Regression of metastatic renal-cell carcinoma after nonmyeloablative allogeneic peripheral-blood stem-cell transplantation

BACKGROUND

Since allogeneic stem-cell transplantation can induce curative graft-versus-leukemia reactions in patients with hematologic cancers, we sought to induce analogous graft-versus-tumor effects in patients with metastatic renal-cell carcinoma by means of nonmyeloablative allogeneic peripheral-blood stem-cell transplantation.

METHODS

Nineteen consecutive patients with refractory metastatic renal-cell carcinoma who had suitable donors received a preparative regimen of cyclophosphamide and fludarabine, followed by an infusion of a peripheral-blood stem-cell allograft from an HLA-identical sibling or a sibling with a mismatch of a single HLA antigen. Cyclosporine, used to prevent graft-versus-host disease, was withdrawn early in patients with mixed T-cell chimerism or disease progression. Patients with no response received up to three infusions of donor lymphocytes.

RESULTS

At the time of the last follow-up, 9 of the 19 patients were alive 287 to 831 days after transplantation (median follow-up, 402 days). Two had died of transplantation-related causes, and eight from progressive disease. In 10 patients (53 percent) metastatic disease regressed; 3 had a complete response, and 7 had a partial response. The patients who had a complete response remained in remission 27, 25, and 16 months after transplantation. Regression of metastases was delayed, occurring a median of 129 days after transplantation, and often followed the withdrawal of cyclosporine and the establishment of complete donor-T-cell chimerism. These results are consistent with a graft-versus-tumor effect.

CONCLUSIONS

Nonmyeloablative allogeneic stem-cell transplantation can induce sustained regression of metastatic renal-cell carcinoma in patients who have had no response to conventional immunotherapy.

Allogeneic stem cell transplantation with fludarabine-based, less intensive conditioning regimens as adoptive immunotherapy in advanced Hodgkin's disease

Six patients with advanced Hodgkin's disease in which multiple conventional treatments (median prior chemotherapy regimens: seven), radiation therapy, and a prior autologous stem cell transplantation (SCT) had failed underwent allogeneic SCT following a fludarabine-based conditioning regimen. Median age was 29 years (22-30). Median time to progression after autologous SCT was 6 months (4-21). Disease status at transplant was refractory relapse (n = 3) and sensitive relapse (n = 3). Cell source was filgrastim-mobilized peripheral blood stem cells from an HLA-identical sibling (n = 4) or matched unrelated donor marrow (n = 2). Conditioning regimens were fludarabine-cyclophosphamide-antithymocyte globulin (n = 4), fludarabine-melphalan (n = 1) and fludarabine-cytarabine-idarubicin (n = 1). Myeloid recovery was prompt, with an absolute neutrophil count > or =500/microl on day 12 (11-15). Median platelet recovery to > or =20000/microl was on day 9 (0-60). Chimerism studies on day 30 indicated 100% donor-derived hematopoiesis in 4/5 evaluable patients (4/4 non-progressors). All responders (3/3) have ongoing 100% donor-derived chimerism. Acute graft-versus-host disease (GVHD) was diagnosed in 4/6 evaluable patients. Chronic GVHD was present in 2/4 evaluable patients. There were no regimen-related deaths. Overall day 100 transplant-related mortality was 2/6 (33%). Three patients have expired and three are alive and progression-free with a median follow-up of 9 months (6-26) post transplant. We conclude that allogeneic stem cell transplantation with fludarabine-based preparative regimens is feasible in these high-risk, heavily pretreated HD patients.

Second allogeneic stem cell transplantation using nonmyeloablative conditioning for patients who relapsed or developed secondary malignancies following autologous transplantation

OBJECTIVE

Second allogeneic stem cell transplants for hematological malignancies are associated with a high incidence of transplant-related mortality due to the cumulative incidence of toxicity of the high-dose chemoradiotherapy traditionally used as an essential component of the conditioning. We have demonstrated previously that nonmyeloablative conditioning for primary allogeneic transplants from both sibling and unrelated donors results in minimal transplant-related toxicity and excellent stem cell engraftment. This study explores the possibility of using nonmyeloablative conditioning to minimize transplant-related toxicity in patients who have undergone second allogeneic transplants.

PATIENTS AND METHODS

Twelve high-risk, heavily treated patients-five with acute myelogenous leukemia (AML); five with non-Hodgkin's lymphoma (NHL); one with Burkitt's lymphoma, and one with acute lymphoblastic leukemia (ALL)-underwent second allogeneic nonmyeloablative stem cell transplantation (NST) from human leukocyte antigen (HLA)-matched donors, 29 (median) (range 3-57) months following their first transplantation procedure. The conditioning consisted of fludarabine 30 mg/m(2) daily for 6 days, busulfan 4 mg/kg daily for 2 days, and anti-T-lymphocyte globulin 10 mg/kg daily for 4 days. Anti-graft-vs-host disease (anti-GVHD) prophylaxis consisted of cyclosporine A alone, 3 mg/kg.

RESULTS

Engraftment was observed in all recipients, with complete and stable chimerism. None of the patients developed veno-occlusive disease of the liver or multi-organ failure. Five very high-risk patients with NHL (n = 3), Burkitt's lymphoma (n = 1), and AML (n = 1) relapsed 2 to 6 months post-transplant, and four of them died. Six patients appear to be disease-free after median follow-up of 23 months. One additional patient died from grade IV hemorrhagic cystitis. Actuarial survival and disease-free survival at 34 months are 56% and 50% respectively, with 95% confidence interval (25-78%).

CONCLUSION

These results suggest that nonmyeloablative conditioning significantly reduces transplant-related toxicity, thus making a second transplant feasible.

Complete remission of idiopathic myelofibrosis following donor lymphocyte infusion after failure of allogeneic transplantation: demonstration of a graft-versus-myelofibrosis effect

A patient with idiopathic myelofibrosis (IM) in the osteosclerotic phase received an allogeneic stem cell transplant. Hemopoietic engraftment was rapid, and full donor chimerism was observed on day +70. However, a few months later, replacement of donor hemopoiesis by the patient's 20q- cell clone was observed, followed by reappearance of the blood IM features, marrow fibrosis and osteosclerosis. At 8 months from transplant donor lymphocytes were infused, which induced chronic GVHD. This resulted in normalization of the blood, with disappearance of the fibrosis and osteosclerosis, effects which persisted 20 months later. This case provides evidence for a graft-versus-disease effect in IM.

Successful allogeneic stem-cell transplantation with prophylactic stepwise G-CSF primed-DLIs for relapse after autologous transplantation in mantle cell lymphoma: a case report and literature review on the evidence of GVL effects in MCL

Mantle cell lymphoma (MCL) is a distinctive clinicopathologic entity and represents 2-8% of all non-Hodgkin's lymphomas. The median survival of patients with MCL is only 3 years, and none of the available conventional chemotherapy regimens appears curative. Encouraging results have been reported with high-dose chemotherapy with autologous stem-cell transplantation (autoSCT). However, a plateau in disease-free survival was not observed in relapsed MCL on the autoSCT trials. Promisingly, alloSCT appears to induce durable remissions via a graft-versus-lymphoma (GVL) effect. Donor lymphocyte infusions (DLIs), by virtue of a GVL effect, have been shown to induce durable remissions in a few cases with refractory MCL that recur after alloSCT. In this article, we review the literature on the evidence of the GVL effects in MCL and describe a patient with relapsed MCL shortly after high-dose chemotherapy with autoSCT. The patient was then successfully treated with Bu/Cy/VP-16 for an alloSCT followed by DLIs in a stepwise fashion. MNCs > 10 x 10(8)/kg were collected by two large-volume leukaphereses from the donor. Harvested stem cells from the 2(nd) day were cryopreserved for the future use as prophylactic DLIs to be given in a stepwise fashion. Cyclosporin and methotrexate were used for GVHD prophylaxis. He had achieved only a partial response by D+64 post transplant. G-CSF-primed cryopreserved DLIs were then infused on D+64 and D+92 to enhance the GVL effect. Grade 3 intestinal GVHD developed 20 days after the 2(nd) DLI and was partially controlled with the combination of cyclosporin, prednisone, and mycophenolate mofetil. Clinical complete remission was observed at D+112, and maintained until the last follow-up day (D+615). Our findings suggest that alloSCT followed by prophylactic DLIs may offer a curative approach to refractory MCL.

Donor lymphocyte infusions for relapsed multiple myeloma after allogeneic stem-cell transplantation: predictive factors for response and long-term outcome

PURPOSE

To determine the efficacy, toxicity, and long-term outcome and prognostic factors of donor lymphocyte infusions (DLI) in patients with relapsed multiple myeloma (MM) after allogeneic stem-cell transplantation (AlloSCT).

MATERIALS AND METHODS

Twenty-seven patients received 52 DLI courses at a median of 30 months after the previous AlloSCT. Reinduction therapy was administered to 13 patients before DLI.

RESULTS

Reinduction therapy was successful in eight of 13 patients. Fourteen patients (52%) responded to DLI, including six patients (22%) who achieved a complete remission (CR). Five patients responded after T-cell dose escalation in subsequent DLIs. Four patients experienced relapse or disease progression (three from partial response and one from CR). Five patients remain in remission more than 30 months after DLI. Major toxicity was acute and chronic graft-versus-host disease (GVHD), which was present in 55% and 26% of patients, respectively. Two patients died from bone marrow aplasia. Median overall survival of all patients was 18 months. Overall survival was 11 months for DLI-resistant patients and has not been reached for the responding patients. In two patients, sustained molecular remission was observed. The factors that were correlated with response to DLI were a T-cell dose of more than 1.10(8) cells/kg, response to reinduction therapy, and chemotherapy-sensitive disease before AlloSCT.

CONCLUSION

These data confirm the potential and durable graft-versus-myeloma effect of DLI in patients with relapsed MM after AlloSCT. Future studies should be aimed at increasing response rates, especially in patients with chemoresistant disease, and reducing toxicity by limiting GVHD. Adjuvant DLI seems an attractive and promising approach for patients who do not achieve a molecular remission after AlloSCT.

Dose-reduced conditioning for allogeneic blood stem cell transplantation: durable engraftment without antithymocyte globulin

Between February 1998 and October 1999, 24 patients with advanced leukemia, lymphoma or solid tumors received G-CSF mobilized peripheral blood stem cells (PBSC) from HLA-matched sibling donors after dose-reduced conditioning therapy. Only patients with reduced performance status or major infectious complications, not eligible for standard transplant procedures, were included. The 5-day conditioning therapy consisted of 3.3 mg/kg intravenous busulphan x 2 days and 30 mg/m2 fludarabine x 5 days. GVHD prophylaxis was performed with either CsA alone (n = 5), CsA combined with short course methotrexate (n = 5) or mycophenolate mofetil (n = 14). The day 100 survival was 95.2% for the whole group. All patients engrafted after a median of 15 days (range, 11-19) and 12.5 days (range, 10-19) for neutrophils and platelets, respectively. The median time to a neutrophil count of <0.5 x 109/l was 7 days (range, 2 to 12). Acute GVHD >I was observed in six patients, whereas eight patients have signs of chronic GVHD. The prospective 12 month overall survival with a median follow-up of 7 months is 63%. Relapse of disease and toxicity associated with chronic GVHD were the main causes of death. The treatment-related mortality was 12.5%. Dose-reduced conditioning using intravenous busulphan and fludarabine allows stable engraftment without ATG in related transplants and leads to a reduction of transplant-related mortality.

Sustaining the graft-versus-tumor effect through posttransplant immunization with granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing tumor vaccines

For many cancers, autologous bone marrow transplantation (BMT) achieves a minimal residual disease state, yet relapse rates remain high. Using a syngeneic murine bone marrow transplant model, we demonstrate that vaccination with irradiated granulocyte-macrophage colony-stimulating factor (GM-CSF)-producing autologous tumor cells is effective in the post-BMT period and actually results in a greater tumor-free survival than vaccination in the nontransplant setting. Employing T cells specific for a model tumor-antigen, we find that transplantation of the tumor-bearing host results in a massive expansion and activation of tumor-specific T cells in the early posttransplant period, but this response rapidly declines in association with tumor progression. Immunization with irradiated GM-CSF tumor cells during the period of immune reconstitution results in the sustained amplification and activation of this response that closely correlates with freedom from relapse. These results demonstrate the feasibility of integrating GM-CSF vaccines in the postautologous BMT setting and suggest mechanisms that may contribute to the observed efficacy of immunization during the critical period of immune reconstitution.

Immunotherapy of hematologic malignancies and metastatic solid tumors in experimental animals and man

Following engraftment of donor hematopoietic cells and induction of host-versus-graft tolerance, immunocompetent lymphocytes of donor origin can induce graft-versus-leukemia (GVL) and graft-versus-tumor (GVT) effects. Engraftment of allogeneic bone marrow cells can be accomplished following non-myeloablative conditioning while possibly controlling graft-versus-host disease (GVHD). GVL and GVT effects may thus be successfully accomplished following non-myeloablative stem cell transplantation (NST) as shown by data derived from experimental animals and man.

New strategies in allogeneic stem cell transplantation: immunotherapy using irradiated allogeneic T cells

Recipients of T cell-depleted allogeneic bone marrow transplants have increased risks of relapse and graft rejection. The addition of donor T cells to the TCD allograft will decrease the risk of graft rejection but will increase the risk of graft-versus-host disease (GVHD). Relapse of leukemia or lymphoma following allogeneic bone marrow transplantation can be successfully treated with post-transplant infusions of donor lymphocytes. A relatively small number of donor T cells can have a profound anti-tumor effect and facilitate engraftment, but has an unpredictable potential for severe GVHD. An alternative to using viable immunocompetent donor immune cells to facilitate engraftment and to treat relapsed patients are donor lymphocytes that have been treated to limit their ability to proliferate and cause GVHD. T cells treated with irradiation retain cytotoxic activity against tumor cells and host immune cells. We have tested the hypothesis that allogeneic donor T cells treated with low-dose irradiation will facilitate engraftment and mediate an anti-leukemia effect in a mouse model of bone marrow transplantation. Multiple infusions of irradiated allogeneic donor lymphocytes in the peri-transplant period had graft-enhancing activity without resulting in GVHD. Murine recipients of irradiated allogeneic splenocytes and allogeneic bone marrow had stable donor-derived hematopoiesis without a significant contribution of irradiated donor cells to the T cell compartment. Removing T cells from the allogeneic splenocytes prior to irradiation largely eliminated their graft facilitating activity. Based upon the promising results of the pre-clinical murine studies, we initiated a phase I clinical trial of multiple infusions of irradiated allogeneic lymphocytes in patients who had relapsed after allogeneic BMT. Of 12 patients treated to date on this study, three have shown objective responses of their leukemia or lymphoma to multiple infusions of irradiated donor lymphocytes. We have initiated a new phase I clinical study to test the efficacy of multiple infusions of irradiated allogeneic cytotoxic T cells to facilitate engraftment in allogeneic transplantation. Successive cohorts of patients will be transplanted with allogeneic stem cells alone, or a combination of allogeneic stem cells and increasing numbers of irradiated allogeneic T cells. Irradiated allogeneic lymphocytes that retain short-term allo-specific cytotoxicity and lack the potential for clonal expansion in vivo can be considered as a novel form of immunotherapy with defined pharmacokinetics.

Autologous and allogeneic stem cell transplantation in multiple myeloma

Multiple myeloma is still an incurable disease. The standard conventional chemotherapy comprises melphalan and prednisone (MP). Combination chemotherapy regimens could not improve the median survival of 36 months observed with MP. In the French IFM90 study, HD therapy with TBI plus melphalan 140 mg/m2 was shown to prolong overall survival and progression-free survival compared to conventional treatment. Nonetheless, most patients eventually succumb due to disease progression. Allogeneic transplantation may induce long-term remissions and even cure, but is hampered by a high transplantation-related mortality (TRM). Currently, efforts are made to reduce this TRM and to evaluate the graft-versus-myeloma effect.

Immunization of allogeneic bone marrow transplant recipients with tumor cell vaccines enhances graft-versus-tumor activity without exacerbating graft-versus-host disease

Allogeneic bone marrow transplantation (BMT) induces 2 closely associated immune responses: graft-versus-tumor (GVT) activity and graft-versus-host disease (GVHD). We have previously shown that pretransplant immunization of allogeneic BMT donors with a recipient-derived tumor cell vaccine increases both GVT activity and lethal GVHD because of the priming of donor T cells against putative minor histocompatibility antigens (mHAgs) on the tumor vaccine cells. The work reported here tested the hypothesis that tumor cell vaccination after BMT would produce an increase in GVT activity without exacerbating GVHD. C3H.SW donor bone marrow and splenocytes were transplanted into major histocompatibility complex-matched, mHAg-mismatched C57BL/6 recipients. One month after BMT, recipients were immunized against either a C57BL/6 myeloid leukemia (C1498) or fibrosarcoma (205). Immunized recipients had a significant increase in survival and protection against tumor growth in both tumor models, and significant tumor protection was seen even in recipients with preexisting micrometastatic cancer before immunization. Alloreactivity appeared to contribute to the in vitro anti-tumor cytolytic activity, but in vivo immunity was tumor specific, and no exacerbation of GVHD was observed. Although the immunodominant mHAg B6(dom1) was shown to be expressed by all B6 tumors tested and was largely responsible for the alloreactivity resulting from tumor immunization of donors, the in vitro alloreactivity of immune recipients was more restricted and was not mediated by recognition of B6(dom1). In conclusion, post-transplant tumor immunization of allogeneic BMT recipients against either a leukemia or a solid tumor can increase GVT activity and survival without exacerbating GVHD.

Potential allogeneic graft-versus-tumor effect in a patient with ovarian cancer

A 33-year-old woman developed progressive ovarian cancer resistant to classical chemotherapy agents. We performed a bone marrow allograft after a myeloablative regimen. During hematological recovery, she developed acute graft-versus-host disease (GVHD). From this time her tumor diminished progressively. One year post transplant she has limited chronic liver GVHD and is still free of disease. The complete remission of advanced ovarian cancer was probably related to the GVHD which might therefore provide a new treatment option for this disease.

Allogeneic hematopoietic stem cell transplantation for advanced mycosis fungoides: evidence of a graft-versus-tumor effect

Allogeneic hematopoietic stem cell transplantation should be considered as a therapeutic option for patients with generalized erythoderma or tumor stage MF. Indeed, the only curative option for MF may be an allogeneic transplant. Bone Marrow Transplantation (2000) 25, 111-113.

Graft-vs.-lymphoma effect in an allogeneic hematopoietic stem cell transplantation model

It is known that an important curative benefit of allogeneic bone marrow transplantation (BAMT) in the treatment of hematolymphoid malignancies is a graft-vs.-tumor (GVT) effect. GVT activity has been attributed to mature immune cells contained within the graft because T-cell depletion of bone marrow results in increased rates of disease relapse post-transplantation. We previously demonstrated successful engraftment of highly purified hematopoietic stem cells (HSCs) transplanted across major histocompatibility complex (MHC) barriers in mice. In the present study, we have developed a preclinical model of allogeneic HSC transplantation into lymphoma-inoculated mice, allowing us to directly test whether purified HSCs have measurable GVT activity. We then performed cotransfer studies of HSCs with purified immune cells to identify which population(s) confers tumor protection and the mechanism by which such cells suppress tumor growth. MHC-mismatched donor-recipient combinations were studied. All of the GVT activity was contained in the CD8+ cell fraction and, at the doses of CD8+ cells tested, tumor protection was separable from acute graft-vs.-host disease (aGVHD). Although there appears to be no functional difference between BM- and splenic-derived CDS8+ cells with regard to GVT activity without aGVHD, this was not the case for purified CD3+ cells. CD3+ cells derived from BM were tumor protective, whereas transplantation of equivalent doses of CD3+ cells purified from spleen resulted in lethal GVHD. The mechanism by which the GVT-conferring cells protect recipient mice from tumors was studied using immune defective mice as donors. We found that an intact pathway of perforin-dependent cytolysis, as well as an intact Fas-ligand pathway, is required in order to exert maximal anti-tumor activity.

Graft-vs.-malignancy with allogeneic blood stem cell transplantation: a potential primary treatment modality

The high-dose chemotherapy and radiation typically used as the preparative regimen for bone marrow transplantation produces considerable morbidity and mortality. An alternative strategy is to utilize a low-dose, non-myeloablative, preparative regimen designed not to eradicate the malignancy, but to provide sufficient immunosuppression to achieve engraftment of an allogeneic hematopoietic graft and allow subsequent development of a graft-vs.-malignancy effect. We studied this approach in patients who were ineligible for standard myeloablative preparative regimens because of advanced age or comorbidities and demonstrated that purine analog (fludarabine or 2-CDA) containing non-myeloablative chemotherapy allows engraftment of HLA-compatible hematopoietic progenitor cells, and extended remissions were observed in approximately half of chemosensitive patients with recurrent AML or CML. Patients with CLL or lymphoma have been effectively treated using a non-myeloablative regimen of fludarabine/cyclophosphamide of fludarabine, cytarabine, cisplatin. This chemotherapy is known to be non-myeloablative and mixed chimerism was anticipated. All patients with engraftment have responded and 67% have achieved complete remission. Maximal responses are slow to develop and occur gradually over a period of several months to one year. Long-term efficacy must still be determined and controlled trials are necessary comparing this approach with alternative therapies as well as standard transplantation regimens.

Graft-versus-myeloma after withdrawal of immunosuppression following allogeneic peripheral stem cell transplantation

There is growing evidence for a graft-versus-myeloma effect following allogeneic stem cell transplantation. We add to this evidence by reporting complete remission achieved by withdrawal of immunosuppression in a patient with multiple myeloma progressing after HLA-identical sibling peripheral stem cell transplantation. De novo chronic graft-versus-host disease coincided with the anti-myeloma effect and responded to treatment. The patient remains in complete remission 3 years after transplant.

Allogeneic hematopoietic transplantation as adoptive immunotherapy. Induction of graft-versus-malignancy as primary therapy

An immune-mediated graft-versus-malignancy effect is important to prevent relapse after allogeneic bone marrow transplant for a range of hematologic malignancies and potentially some solid tumors. Graft-versus-leukemia (GVL) effects as seen in response to donor lymphocyte infusions have been most prominent against indolent malignancies including chronic myelogenous leukemia, chronic lymphocytic leukemia, and low-grade lymphoma. Acute myelogenous leukemia and multiple myeloma may also respond. An alternative strategy for allogeneic transplantation is to avoid the toxicity of high-dose chemoradiotherapy and use a relatively nontoxic, nonablative preparative regimen to achieve engraftment, allowing subsequent infusion of additional donor lymphocytes to mediate GVL. Fludarabine-based nonablative chemotherapy agents, using standard dose combinations, produce moderate myelosuppression but are sufficiently immunosuppressive to allow engraftment of an allogeneic hematopoietic transplant and generation of graft-versus-malignancy effects.

[Effect of activated donor-type NK cells on allogeneic bone marrow transplantation in mice]

OBJECTIVE

To study the effect of activated donor-type NK cells on allogeneic bone marrow transplantation(BMT).

METHODS

Four hours before or 72 hours after transfusing bone marrow cells(containing T cells), the activated donor-type NK cells were injected into tumor-bearing mice conditioned by irradiation. The effect of these NK cells were assessed by CFU-S, CFU-GM, survival, body weight, histopathology and lung metastases in the recipients.

RESULTS

The transfusion of activated donor-type NK cells markedly increased CFU-S and CFU-GM numbers. When these NK cells were transfused 4 hours before BMT, they augmented GVT yet inhibited GVHD as evidenced by increases in survival duration and body weight, reduction in grade of histopathological changes and decrease in lung metastases. However, when activated donor-type NK cells were transfused 72 hours after BMT, they exacerbated GVHD.

CONCLUSIONS

The activated donor-type NK cells could prevent GVHD and produce significant GVT effects and also resulted in greater hematopoietic reconstitution if they were at the initial stage of allogeneic BMT in mice. Thereafter, the activated donor-type NK cells were detrimental and could exacerbate the subsequent GVHD, these results also demonstrated that GVT and GVHD could be dissociable phenomena.

Hematopoietic donor chimerism and graft-versus-myeloma effect in relapse of multiple myeloma after allogeneic bone marrow transplantation

A large group of patients relapsing after allogeneic bone marrow transplantation (BMT) have obtained remission after infusion of leukocytes from their original donor, suggesting a graft-versus-myeloma effect. However, side effects such as graft-versus-host disease and myelosuppression are severe, and sometimes fatal, complications of this therapeutic approach. Previously we demonstrated that patients with leukemia who lack donor hematopoiesis in relapse after BMT experience severe and lasting aplasia after infusion of donor leukocytes. In two patients - one with extramedullary and one with marrow relapse after a sex-mismatched transplantation - we analyzed hematopoietic chimerism by cell sorting and bone marrow cultures. CD34-positive cells, CD4-CD8-positive cells, committed progenitors, and LTC-IC were of donor origin, as demonstrated by two-color fluorescence in situ hybridization (FISH). Additionally, in relapse complete donor T-cell chimerism was seen. In contrast, plasma cells were of recipient origin in the patient who had a relapse in the bone marrow. Both patients were treated with infusions of donor leukocytes from their original donor. Neither patient suffered myelosuppression, and one achieved a stable complete remission.

T-cell depletion plus salvage immunotherapy with donor leukocyte infusions as a strategy to treat chronic-phase chronic myelogenous leukemia patients undergoing HLA-identical sibling marrow transplantation

T-cell depletion (TCD) of the donor marrow graft has been shown to reduce the severity of graft-versus-host disease (GVHD) in patients with chronic-phase (CP) chronic myelogenous leukemia (CML) undergoing HLA-identical sibling allogeneic marrow transplantation. However, there has been a corresponding reduction in the graft-versus-leukemia effect so that any decrease in GVHD-related mortality has been offset by an increased rate of disease relapse. Therapy of recurrent disease with donor leukocyte infusions (DLI) has been proven to be effective salvage therapy for the majority of patients who relapse after allogeneic BMT with CP CML. However, the overall impact of salvage DLI therapy on the survival of CP CML patients initially transplanted with TCD marrow grafts is not defined. To address this question, we have evaluated a clinical strategy of TCD followed by targeted adoptive immunotherapy with DLI in 25 CP CML patients undergoing allogeneic BMT from HLA-identical siblings. All patients received a standardized preparative regimen along with ex vivo TCD and posttransplant cyclosporine as GVHD prophylaxis. Durable engraftment was observed in all 25 patients. The incidence of grade II to IV acute GVHD was 8%. The cumulative incidence of transplant-related mortality (TRM) was 4%, and the 1-year probability of overall survival was 96%. The 3-year cumulative relapse incidence was 49%. All relapsed patients received DLI to reinduce remission. The total T-cell dose administered to these patients varied from 0.1 to 5.0 x 10(8) T cells/kg. Complete responses were observed in 12 of 14 patients, with 1 additional patient still too early to evaluate. Three patients died of GVHD after DLI, and 1 relapsed into blast crisis after a transient cytogenetic remission. Of the remaining 10 patients, 8 are in molecular remission, 1 is alive in relapse, and 1 is receiving DLI treatment. The median follow-up after infusion of surviving DLI patients in remission is 5.3 years. The probability of overall 5-year survival for the entire population is 80%, with a median follow-up of 6.4 years. We conclude that the clinical strategy of TCD followed by targeted adoptive immunotherapy with DLI for those patients with evidence of recurrent disease is a viable transplant strategy for CP CML, resulting in 80% survival and a low risk of acute GVHD and transplant-related mortality.

Antileukemic effect of interleukin-2-transduced murine bone marrow after autologous transplantation

Myeloablative chemotherapy or radiation therapy supported by autologous stem cell transplantation (SCT) for the treatment of hematologic malignancies such as acute leukemia, lymphoma, and myeloma is associated with high rates of relapse. The reasons for this are 1) autologous transplantation lacks the in vivo graft-vs.-tumor (GVT) effect associated with allogeneic SCT, which is effective in controlling or eliminating residual malignant cells remaining in the body after high-dose therapy, and 2) contaminating malignant cells in the autologous graft are reinfused into the body. Some researchers have attempted to administer immunomodulatory cytokines to simulate a GVT effect, and although this has shown some efficacy, it has several disadvantages. These include high toxicity associated with systemic administration, a short in vivo half-life, and insufficient levels reaching the site of residual disease. As an alternative, we investigated whether delivery of the cytokine interleukin (IL)-2 to the bone marrow can exert an antileukemic effect while avoiding the problems associated with systemic administration. We describe the delivery of IL-2 to the bone marrow by transplantation of syngeneic bone marrow, retrovirally transduced with the gene for IL-2, into lethally irradiated mice. We were able to efficiently transduce murine bone marrow with the IL-2 gene without adversely affecting clonogenic output from hematopoietic progenitors, and we were able to achieve expression of the transgene in transplanted animals. However, IL-2 transduction inhibited hematopoietic reconstitution in lethally irradiated mice. Marrow transduced with high-titer, high-expressing IL-2 retrovirus failed to engraft, and a low-titer, low-expressing IL-2 retrovirus also demonstrated reduced engraftment, although engraftment was sufficient to support survival of transplanted mice. Long-term, low-level expression of the IL-2 transgene was detectable in these mice and was effective in exerting an antileukemic effect. Mice transplanted with control marrow and challenged with leukemic cells suffered 100% mortality within 70 days, whereas mice transplanted with IL-2-transduced marrow exhibited 50% survival over the 175-day duration of this study. The work shows that delivery of immunomodulatory cytokines to the bone marrow can be achieved by transplantation of genetically modified hematopoietic cells. Furthermore, low-level IL-2 expression can exert an antileukemic effect. These data suggest that this may be an effective immunotherapeutic strategy to reduce relapse after autologous transplantation, but the selection and expression of the cytokine must be carefully considered to minimize adverse effects on hematopoiesis.

Sialoadhesin-positive host macrophages play an essential role in graft-versus-leukemia reactivity in mice

We recently established an effective immune T-cell-mediated graft-versus-leukemia (GVL) murine model system in which complete tumor remissions were achievable even in advanced metastasized cancer. We now describe that this T-cell-mediated therapy is dependent on host macrophages expressing the lymphocyte adhesion molecule sialoadhesin (Sn). Depletion of Kupffer cells in tumor-bearing mice during adoptive immunotherapy (ADI) or the treatment of these animals with anti-Sn monoclonal antibodies led to complete or partial inhibition of the immune T-cell-mediated therapeutic effect. Furthermore, Sn+ host macrophages in livers formed clusters during ADI with donor CD8 T cells. To test for a possible antigen presentation function of these macrophages, we used as an in vitro model the antigen beta-galactosidase for which a dominant major histocompatibility complex (MHC) class I Ld-restricted peptide epitope is known to be recognized by specific CD8 cytotoxic T lymphocytes (CTL). We demonstrate that purified Sn+ macrophages can process exogenous beta-galactosidase and stimulate MHC class I peptide-restricted CTL responses. Thus, Sn+ macrophages, which are significantly increased in the liver after ADI, may process tumor-derived proteins via the MHC class I pathway as well as via the MHC class II pathway, as shown previously, and present respective peptide epitopes to CD8 as well as to CD4 immune T cells, respectively. The synergistic interactions observed before between immune CD4 and CD8 T cells during ADI could thus occur in the observed clusters with Sn+ host macrophages.

Granulocyte colony-stimulating factor-mobilized allogeneic stem cell transplantation maintains graft-versus-leukemia effects through a perforin-dependent pathway while preventing graft-versus-host disease

Minimization of graft-versus-host disease (GVHD) with preservation of the graft-versus-leukemia (GVL) effect is a crucial step to improve the overall survival of allogeneic bone marrow transplantation (BMT) for patients with hematological malignancies. We and other investigators have shown that granulocyte colony-stimulating factor (G-CSF)-mobilized allogeneic peripheral stem cell transplantation (PBSCT) reduces the severity of acute GVHD in murine models. In this study, we investigated whether G-CSF-mobilized PBSC maintain their GVL effect in a murine allogeneic transplant model (B6 --> B6D2F1). B6 mice (H-2(b)) were injected subcutaneously with human G-CSF (100 micrograms/kg/d) for 6 days and their splenocytes were harvested on day 7 as a source of PBSC. G-CSF mobilization dramatically improved transplant survival compared with nonmobilized controls (95% v 0%, P <.001). Systemic levels of lipopolysaccharide and tumor necrosis factor-alpha were markedly reduced in recipients of allogeneic G-CSF-mobilized donors, but cytolytic T lymphocyte (CTL) activity against host tumor target cells p815 was retained in those recipients. When leukemia was induced in recipients by coinjection of p815 tumor cells (H-2(d)) at the time of transplantation, all surviving recipients of G-CSF-mobilized B6 donors were leukemia-free at day 70 after transplant, whereas all mice who received T-cell-depleted (TCD) splenocytes from G-CSF-mobilized B6 donors died of leukemia. When splenocytes from G-CSF-mobilized perforin-deficient (pfp-/-) mice were used for transplantation, 90% of recipients died of leukemia, demonstrating that perforin is a crucial pathway mediating GVL effects after G-CSF-mobilized PBSCT. These data illustrate that G-CSF-mobilized allogeneic PBSCT separate GVL from GVHD by preserving perforin-dependent donor CTL activity while reducing systemic inflammation.

Graft-versus-lymphoma effect after allogeneic peripheral blood stem cell transplantation for primary central nervous system lymphoma

Allogeneic peripheral blood stem cell transplantation (allo PBSCT) is a recognized treatment modality for hematological malignancies resistant to conventional chemoradiotherapy. The post-transplant immune-mediated graft-versus-leukemia effect has major curative potential. In this case presentation, the allogeneic approach to resistant recurrent primary central nervous system (CNS) lymphoma using peripheral blood stem cells from an HLA identical sibling after immuno-suppressive non-myeloablative conditioning, was examined clinically. The patient in question had relapsing refractory primary CNS lymphoma and is the first to be treated with this modality. She developed early skin and liver-localized grade II graft-versus-host disease after allo PBSCT, which then responded to short-term treatment. Chimeric studies at the time showed 100% donor cells and repeated magnetic resonance imaging of the brain revealed gradual shrinkage of the tumor. Three months after transplant the cerebral mass was no longer evident and currently, 30 months after transplantation, the patient continues to be disease free. The absence of any signs of malignancy suggests the development of a durable graft-versus-lymphoma effect in this brain tumor and indicates that this effect may be achieved even after non-myeloablative conditioning.

Prophylactic reinfusion of T cells for T cell-depleted allogeneic bone marrow transplantation

To increase the graft-vs.-leukemia (GVL) effect while maintaining a low mortality from graft-vs.-host disease (GVHD), we conducted a prospective study of T cell titration for 144 patients (90 related, 54 unrelated) between June 1994 and June 1997. Following infusion of a T cell-depleted marrow graft, predetermined doses of T cells, based on the risk factors for GVHD, were administered up to 3 times if greater than a grade II acute GVHD was not seen. Graft failure occurred in three unrelated recipients (2%). Cumulative grades II-IV acute GVHD were seen in 58 +/- 9% of all recipients; 52 +/- 11% related and 75 +/- 13% unrelated. The incidence of grades II-IV acute GVHD following the third add-back (AB) of T cells 78 median days after marrow infusion was lower than that of the earlier ABs: first AB, 36 +/- 8%; second AB, 32 +/- 11%; third AB, 15 +/- 12% (p < 0.05). Chronic GVHD occurred in 56 +/- 12% of related and 79 +/- 16% of unrelated patients. Six died of acute GVHD and two died of chronic GVHD, with an overall GVHD mortality of 6 +/- 4%. In multivariate analyses, unrelated recipients and patients at low risk for GVHD who received a larger number of T cells were identified as patient groups with significant risk for acute and chronic GVHD (both p < 0.05). Unrelated transplant is also shown to be significant for GVHD-related death (p < 0.01). Relapse-free survival of patients with leukemia was shown to be most dependent on chronic GVHD and grades II-IV acute GVHD (both p < 0.01). Anti-leukemic activity independent of GVHD was not observed.

Extramedullary relapse despite graft-versus-leukemia effect after bone marrow transplantation in a girl with juvenile myelomonocytic leukemia

A 12 year-old girl with juvenile myelomonocytic leukemia (JMML) and monosomy 7 underwent allogeneic bone marrow transplantation (BMT) from her HLA-matched brother. To monitor the engraftment and the course of the disease we used fluorescence in situ hybridization (FISH) with probes specific for the centromeres of chromosomes X, Y and 7. Complete hematological remission was achieved and confirmed by the virtually exclusive presence of normal male cells in the bone marrow (BM). Acute graft-versus host disease (GvHD) was treated with prednisone and cyclosporine A (CSA) and female cells with monosomy 7 reoccurred in the peripheral blood (PB) and BM. After discontinuation of the immunosuppressive therapy, the leukemic cells with monosomy 7 disappeared again from these compartments. One year after transplantation, isolated extramedullary relapses occurred in lymph nodes and skin, followed by dissemination of blast cells into the BM, whereas the PB cells remained of donor origin. The fact that the leukemic cells fluctuated with the intensity of the immunosuppressive treatment provides evidence of a graft versus leukemia (GvL) effect in this unusually old girl with JMML with a unique extramedullary disease progression.

Feasibility of immunotherapy of relapsed leukemia with ex vivo-generated cytotoxic T lymphocytes specific for hematopoietic system-restricted minor histocompatibility antigens

Allogeneic bone marrow transplantation (BMT) is a common treatment of hematologic malignancies. Recurrence of the underlying malignancy is a major cause of treatment failure. Donor-derived cytotoxic T lymphocytes (CTLs) specific for patients' minor histocompatibility antigens (mHags) play an important role in both graft-versus-host disease (GVHD) and graft-versus-leukemia (GVL) reactivities. mHags HA-1 and HA-2 induce HLA-A*0201-restricted CTLs in vivo and are exclusively expressed on hematopoietic cells, including leukemic cells and leukemic precursors, but not on fibroblasts, keratinocytes, or liver cells. The chemical nature of the mHags HA-1 and HA-2 is known. We investigated the feasibility of ex vivo generation of mHag HA-1- and HA-2-specific CTLs from unprimed mHag HA-1- and/or HA-2-negative healthy blood donors. HA-1 and HA-2 synthetic peptide-pulsed dendritic cells (DCs) were used as antigen-presenting cells (APC) to stimulate autologous unprimed CD8(+) T cells. The ex vivo-generated HA-1- and HA-2-specific CTLs efficiently lyse leukemic cells derived from acute myeloid leukemia (AML) and acute lymphoid leukemia (ALL) patients. No lytic reactivity was detected against nonhematopoietic cells. Sufficient numbers of the CTLs can be obtained for the adoptive immunotherapy purposes. In conclusion, we present a feasible, novel therapy for the treatment for relapsed leukemia after BMT with a low risk of GVHD.

Relapse of chronic myeloid leukaemia 14 years after allogeneic bone marrow transplantation

Allogeneic bone marrow transplantation (BMT) is the treatment of choice for patients with chronic myeloid leukaemia (CML) who are relatively young and have suitable donors. Relapse is rare more than 5 years after allografting. We describe a patient who relapsed with myeloid blast transformation 14 years after allografting. This case suggests that leukaemia stem cells may on occasion remain quiescent for long periods and emphasises the importance of long-term follow-up after transplantation for CML.

Enhancement of graft-versus-tumor activity and graft-versus-host disease by pretransplant immunization of allogeneic bone marrow donors with a recipient-derived tumor cell vaccine

Allogeneic bone marrow transplantation (BMT) can be accompanied by a beneficial T cell-mediated antitumor immune response known as graft-versus-tumor (GVT) activity. However, BMT donor T cells are not exposed to target antigens of GVT activity until transfer to the host, where tumor antigen presentation may be suboptimal. This study tested in a murine model the hypothesis that immunization of MHC-matched allogeneic donors with a recipient-derived tumor cell vaccine would substantially increase GVT activity and extend survival of BMT recipients with preexisting micrometastatic tumor. C3H.SW and C57BL/10 mice were immunized against a C57BL/6-derived fibrosarcoma or leukemia, and they were used as BMT donors. Recipients were H-2-matched, minor histocompatibility antigen-mismatched C57BL/6 mice with previously established micrometastatic tumors. Donor immunization led to a significant increase in GVT activity that was T cell dependent and cell dose dependent. In some settings, donor immunization also prolonged survival of recipients with preexisting micrometastatic tumors. However, donor immunization significantly increased the incidence of fatal graft-versus-host disease such that long-term survival was uncommon. In vitro cytotoxicity assays indicated that donor immunization induced both tumor-selective and alloreactive cytolytic T-cell populations. In vivo cross-protection assays showed that a substantial portion of the GVT effect was mediated by alloreactive cells not specific for the immunizing tumor. In conclusion, immunization of allogeneic BMT donors with a recipient-derived whole tumor cell vaccine substantially increases GVT activity but also exacerbates graft-versus-host disease.

Allogenic bone marrow transplantation as a treatment for adult T-cell leukemia

We performed allogenic bone marrow transplantation (BMT) in two adult T-cell leukemia (ATL) patients with HLA-identical siblings as donors. One patient, with acute ATL, relapsed 3 months after BMT. The other, with chronic ATL, has become free of disease over 18 months after the BMT from his human T-cell lymphotropic virus type 1 (HTLV-1)-negative sibling, and we were unable to detect HTLV-1 in the patient's peripheral blood. Based on our results and those of others, although there have been limited numbers of patients, BMT may represent the only potentially curative treatment for ATL, and the presence of graft-vs.-host disease tends to be related to good results, which suggests the possibility that graft-vs.-leukemia effects may play an important role in allogenic BMT for ATL.

Allogeneic cell-mediated immunotherapy for eradication of minimal residual disease: comparison of T-cell and IL-2 activated killer (LAK) cell-mediated adoptive immunotherapy in murine models

In the course of allogeneic bone marrow transplantation (BMT), avoiding graft-versus-host disease (GVHD) while retaining the antileukemic effects of the T cells remains a major challenge. T-cell depletion (TCD) reduces the incidence of GVHD but increases the relapse rate after allogeneic BMT. We attempted to develop a regimen that would retain or increase the graft-versus-leukemia effect induced by donor T cells while preventing GVHD. Immunosuppressed mice were given immunocompetent donor cells, i.e., fresh lymphocytes or lymphokine-activated killer (LAK) cells differing from the host in major (MHC) or minor (MiHC) histocompatibility antigens. Engraftment of donor cells was documented by polymerase chain reaction analysis. Administration of MHC- and MiHC-incompatible allogeneic LAK cells, especially in conjunction with recombinant interleukin-2 (rIL-2), increased disease manifestations and mortality associated with GVHD. On the other hand, irradiated LAK cells or TCD-LAK cells prevented GVHD in both mice models studied. Phenotypic analysis of LAK cells demonstrated that CD8(+)-equivalent (Lyt-2) T cells are of significance in aggravation of GVHD. The in vitro cytotoxic capacity of LAK cells against MHC-nonrestricted target cells was not reduced by either irradiation or TCD. These results provide the background for designing improved protocols for immunotherapy of residual disease after BMT. In addition, the data imply that antitumor effects may be retained by irradiated rIL-2-activated allogeneic cells without causing GVHD. Whereas unmodified allogeneic LAK cells can induce more effective graft-versus-leukemia effects at the cost of GVHD, irradiated allogeneic donor LAK cells might play some role in eradication of minimal residual disease following autologous or allogeneic BMT without causing GVHD.

Ex vivo depletion of T cells from bone marrow grafts with CAMPATH-1 in acute leukemia: graft-versus-host disease and graft-versus-leukemia effect

BACKGROUND

Preventing graft-versus-host disease (GVHD) by depletion of T lymphocytes from the stem cell graft for transplantation remains controversial, mainly because of the perceived increase in disease recurrence.

METHODS

We retrospectively analyzed the outcome of 50 consecutive individuals in remission of acute lymphoblastic leukemia (n=13; 8 in complete remission [CR]1) or acute myeloblastic leukemia (n=37; 33 in CR1), who had received marrow grafts from HLA-identical siblings. The conditioning regimen included six 2-Gy fractions of total body irradiation, succeeded by cyclophosphamide at 120 mg/kg (with mesna) followed by four fractions of 1.5 Gy to lymphoid areas. Bone marrow (n=38) or peripheral blood mobilized donor mononuclear cells (n=12) were exposed ex vivo to CAMPATH-1 (IgM and complement, or IgG; antiCD52) antibodies, without any further posttransplantation immunosuppression.

RESULTS

Median patient age was 31 (range 14-51) years; 12 patients were 40 or older. Thirty-two patients were male. One patient died of pulmonary hemorrhage on day 10; another died on day 29 of interstitial pneumonitis. Except for one early death, all patients engrafted. Ten (21%) of the remaining 48 who were at risk, developed GVHD. In none was it greater than grade II. Eight patients developed serious viral infections. Four died of cytomegalovirus pneumonia, adenovirus hepatitis, and human immunodeficiency. Overall, 11 patients (22%) relapsed (4 of 33 acute myeloblastic leukemia in CR1) at a median of 235 (range 46-528) days. Mean posttransplantation follow-up was 1062 (median 560; range 10-4177) days. Thirty-three patients (66%) remained disease free at a mean of 1,118 (median 1439; range 159-4,177) days. For all patients, the performance status was between 82% and 100% (median 100).

CONCLUSION

T-cell depletion with CAMPATH-1 effectively prevents GVHD, particularly the severe acute forms, without leading to excessive risk of relapse in acute leukemia.

Rejection of an MHC class II negative tumor following induction of murine syngeneic graft-versus-host disease

Cyclosporin A (CsA) has been used clinically to induce graft-versus-host disease following autologous bone marrow transplantation in an attempt to destroy residual leukemia cells and reduce relapse. To analyze the antitumor potential of murine syngeneic graft-versus-host disease (SGVHD), C3H/HeN mice were lethally irradiated, reconstituted with T cell-depleted syngeneic bone marrow (ATBM) and treated with CsA for 21 days. Graft-versus-leukemia activity was assessed by challenging groups of olive oil-treated control ATBM (OO-ATBM) and CsA-treated (CsA-ATBM) mice 1 week after CsA therapy with graded doses of the syngeneic 38C13 B cell lymphoma. Following CsA treatment, up to 70% of CsA-ATBM developed SGVHD and more than 70% of the animals injected with 500 38C13 cells exhibited long-term survival (MST >80 days). In contrast, none of the OO-ATBM control mice developed SGVHD, and more than 75% of these mice died following injection of 500 38C13 tumor cells (MST = 34 days). Long-term survivors were not resistant to tumor challenge suggesting that tumor-specific immunity did not develop. Finally, class II negative 38C13 cells cultured in IL-4 or IL-10 were not inducible for MHC class II molecules, demonstrating that class II-independent antitumor mechanisms exist in SGVHD mice.

Donor-recipient polymorphism of the proteinase 3 gene: a potential target for T-cell alloresponses to myeloid leukemia

The curative effect of allogeneic bone marrow transplantation (BMT) is in part due to an alloresponse of donor lymphocytes against recipient leukemia termed the graft versus leukemia (GvL) effect. To identify target antigens for the GvL response on leukemia cells, we looked for polymorphism of proteinase 3, a primary granule protein overexpressed in myeloid leukemias. The study was carried out in 10 patients with hematologic diseases and their HLA-identical marrow donors. By polymerase chain reaction (PCR)-single strand conformation polymorphism assay, followed by direct sequencing of the PCR products, we found seven DNA polymorphisms. One of them encodes for either an isoleucine or a valine at position 119 of the amino acid sequence. Peptides that span the polymorphic site, at amino acids 115-124, were shown to bind in vitro to the HLA-A2 molecule. We screened 23 HLA-A2 patients with myeloid leukemia and their HLA-identical donors for this polymorphism. No relapse was found in the group of 4 evaluable patients who possessed at least one allele absent in their donor, whereas 7 of the 15 remaining evaluable patients relapsed. These data support the possibility that T-cell responses to allelic differences of proteinase 3 could be used as a basis for designing leukemia-specific adoptive T-cell therapy in acute and chronic myeloid leukemias.

Graft-versus-leukemia reactivity involves cluster formation between superantigen-reactive donor T lymphocytes and host macrophages

T-cell-mediated antitumor effects play an important role clinically in allogeneic graft-versus-leukemia (GvL) reactivity, whereas T-cell-mediated antihost effects are associated with a risk of developing graft-versus-host (GvH) disease. GvL and GvH were compared in an animal tumor model system after the systemic transfer of allogeneic antitumor immune T lymphocytes from B10.D2 [H-2d; minor lymphocyte-stimulating antigen (Mls)b] mice into ESb-MP tumor-bearing or normal DBA/2 (H-2d; Mls(a)) mice. Here we demonstrate that this T-cell-mediated therapy involves the formation of clusters of donor CD4 and CD8 T cells with host macrophages, in particular, with a subpopulation expressing the lymphocyte adhesion molecule sialoadhesin. DBA/2 mice and the derived tumor ESb-MP express viral superantigen 7 (Mls(a)), an endogenous viral superantigen that is absent from B10.D2 mice. To test the contribution of viral superantigen 7-reactive Vbeta6 donor T cells in the GvL-mediated eradication of liver metastases, we performed immunohistological and transmission electron microscopy studies. Vbeta6+ CD4 and CD8 T cells from B10.D2 donors formed tight clusters with host sialoadhesin-positive macrophages, and transmission electron microscopy pictures revealed direct membrane-membrane interactions between T cells and macrophages. Clusters were more abundant and consisted of more cells in tumor-bearing hosts (GvL model) than in non-tumor-bearing hosts (GvH model). In addition, Vbeta6 T cells within the clusters showed a strong proliferation activity, indicating stimulation. Moreover, in an in vitro tumor cytostasis assay, primed as well as nonprimed purified Vbeta6 T cells from donor mice were able to inhibit the proliferation of superantigen-expressing ESb-MP lymphoma cells. This suggests that the transferred superantigen-reactive Vbeta6 T cells contribute to the eradication of metastases. The observed cell clusters might be sites for antigen presentation and the activation of tumor-reactive T cells.

Graft-versus-host disease and graft-versus-leukemia effect in mice grafted with peripheral newborn blood

We previously used peripheral newborn blood (NBB) as a possible in vivo experimental model for cord blood (CB) transplantation and showed that B10.D2 NBB cells successfully reconstituted adult (DBA/2 x B10.D2)F1 mice without causing graft-versus-host disease (GVHD), probably because of their phenotypic and functional immaturity. Here we investigated the influence of T-cell maturation occurring in NBB cells during the early postbirth period on the degree of engraftment, the incidence of GVHD, and the graft-versus-leukemia (GVL) potential. These parameters were compared in recipients grafted with bone marrow (BM) cells. We observed an increased percentage of CD4(+) mature T cells accompanied by the acquisition of proliferative responses to phytohemagglutinin (PHA) and to allogeneic cells of day-5 NBB cells. The capacity of day-2 NBB to engraft was moderately reduced and recipients developing GVHD were occasionally observed after the graft of day-5 NBB cells. No GVL effect was evidenced regardless of the time of postbirth blood collection. However, the GVL effect can be obtained by the delayed infusion of donor mature T cells to recipients grafted with day-0 NBB, without causing GVHD. In contrast, the same protocol applied to mice grafted with BM cells induced GVHD mortality of all recipients. Interleukin (IL)-10 but not IL-2 messenger RNA was expressed in NBB cells as opposed to BM cells. These findings suggest that, in terms of GVHD incidence, delayed infusion of mature T cells as post-transplant tumor immunotherapy would be more effective when applied after CB than after BM transplantation.

Kinetics of the graft-versus-leukemia response after donor leukocyte infusions for relapsed chronic myeloid leukemia after allogeneic bone marrow transplantation

Little is known about the mechanisms and the kinetics of the so-called graft-versus-leukemia (GVL) response induced by donor lymphocyte infusions (DLI) in patients with leukemic relapse after allogeneic bone marrow transplantation (BMT). We sought to elucidate this problem by sequentially studying three patients with relapsed chronic myeloid leukemia after sex-mismatched BMT from time before donor leukocyte infusion until achievement of complete molecular remission. Lineage-specific chimerism was assessed longitudinally by a combined fluorescent immunophenotyping and sex chromosome-specific in situ hybridization approach. Results were related to quantitative detection of bcr-abl transcripts by competitive differential reverse transcriptase-polymerase chain reaction (RT-PCR), qualitative bcr-abl RT-PCR, and multiplex PCR-based DNA donor/recipient chimerism. All patients had predominant donor lymphopoiesis at the time of DLI, suggesting a state of tolerance to recipient leukemic and/or normal cells. In contrast, granulopoiesis and erythropoiesis were mainly recipient derived in both patients with hematologic relapse and partly recipient derived in the patient with molecular relapse. Eighty percent, 90%, and 8% of CD34(+) cells, respectively, were found to be of recipient origin at relapse, and few donor stem cells predicted for cytopenia post-DLI. Responses were seen after a time lag of 5 to 13 weeks after DLI and resulted in reversal to full donor chimerism within a critical switch period of 4 to 5 weeks. A sudden decrease in recipient cells was paralleled by a sharp decrease in bcr-abl transcript numbers detectable several weeks before achievement of molecular remission and onset of clinical graft-versus-host disease (GVHD). This response pattern was confirmed by retrospective RT-PCR analysis in an additional five patients. Prospective monitoring of stem cell chimerism and response may enable us to individually tailor adoptive immunotherapy in the future.

Minor histocompatibility antigens as targets for T-cell therapy after bone marrow transplantation

In allogeneic bone marrow transplantation, differences between donor and recipient at minor histocompatibility loci, which encode allelic proteins containing variant peptide sequences, may result in adverse immune reactions such as graft-versus-host disease (GVHD), or graft rejection, but also a beneficial graft versus leukemia (GVL) response. Some minor H antigens are restricted in their expression to hematopoietic cells, including leukemic progenitors, suggesting it may be possible to separate GVHD and GVL responses. The antigenic peptides for a few human minor H antigens have been identified, and efforts to identify the genes encoding minor H antigens are being pursued. These advances promise to provide a more detailed understanding of the immunobiology and pathogenesis of GVHD and GVL responses and opportunities to selectively augment T-cell responses that promote a GVL effect by adoptive immunotherapy with T-cell clones specific for defined minor H determinants.

Graft-versus-myeloma

Whereas patients with multiple myeloma continue to relapse after autologous transplantation and are unlikely to be cured, the probability of progression is less after allogeneic transplantation and a proportion of patients may be cured. This is attributable to an immunologically mediated graft-versus-myeloma (GVM) effect which is akin to the well-known graft-versus-leukemia effect. The available clinical and experimental evidence strongly support the existence of GVM, but it is not known whether GVM is separable from graft-versus-host disease (GVHD) in practice. The best way to exploit GVM reactions is unclear, and the morbidity and mortality associated with GVHD undermine long-term survival. There is usually a time lag of a few weeks between immune intervention and disease response. There is a propensity for extramedullary disease recurrence in patients whose marrow disease is controlled with immunologic manipulation. Exploration of GVM outside conventional allogeneic transplantation or after autologous transplantation is necessary to increase the number of patients likely to benefit from this phenomenon and to make it safer. This article reviews the currently available literature on the subject.

Hematopoietic stem cell transplantation for chronic lymphocytic leukemia

Conventional therapies for chronic lymphocytic leukemia are not likely to provide a cure, prompting the use of more aggressive approaches. High-dose therapy with autologous and allogeneic bone marrow or blood stem cell transplantation appear to induce a prolonged period of disease-free survival in selected patients with this indolent disease. Significant questions were raised, however, in terms of survival benefit, the value of purging, the presence of graft-versus-leukemia effect, and the timing of transplantation. The survey presents the main results obtained in the area of transplantation for chronic lymphocytic leukemia and critically discusses them in light of the current debate.

Herpes simplex virus thymidine kinase gene transfer for controlled graft-versus-host disease and graft-versus-leukemia: clinical follow-up and improved new vectors

We previously demonstrated that severe graft-versus-host disease (GvHD), associated with the therapeutic infusion of donor lymphocytes after allogeneic marrow transplantation (BMT), can be efficiently controlled by the SFCMM-2-mediated expression of the herpes simplex virus thymidine kinase (HSV-tk) suicide gene into the allogeneic lymphocytes. This was achieved by selective elimination of transduced lymphocytes by ganciclovir (GCV) infusion. Despite the positive results of the pilot clinical trial, two vector-related limitations were observed. The induction of a strong immune response against genetically modified cells was observed in two patients. In addition, the only patient who developed chronic GvHD showed only partial response to ganciclovir treatment. In an attempt to overcome these limitations, we developed a new generation of vectors. The neomycin resistance (neoR) gene was removed from the SFCMM-3 and SFCMM-4 retroviral vectors. These vectors are less immunogenic and able to confer higher ganciclovir sensitivity to transduced human lymphocytes. All the vectors carry a modified form of the low-affinity nerve growth factor receptor cDNA, as cell surface selectable marker (deltaLNGFR). The vectors were compared in terms of gene transfer efficiency, and ability to confer high and specific sensitivity to ganciclovir. The SFCMM-3 vector, carrying the entire HSV-tk gene driven by the LTR promoter, allows efficient transduction of human T lymphocytes and confers the highest GCV sensitivity to transduced lymphocytes with a high and a low proliferation index. The expression of the deltaLNGFR marker allows an easier in vitro manipulation and a faster immune selection of transduced cells compared with neoR selection. Finally, the elimination of the neoR gene removes a potent immunogen from transduced lymphocytes.

Low incidence of acute graft-versus-host disease and recurrent leukaemia in patients undergoing allogeneic haemopoietic stem cell transplantation from sibling donors with methotrexate and dose-monitored cyclosporin A prophylaxis

One of the major aims of allogeneic haemopoietic stem cell transplantation has been the effective suppression of graft-versus-host disease (GVHD) without loss of a graft-versus-leukaemia effect. For GVHD suppression, one of the most frequently used regimens has been the combination of cyclosporin (CsA) and a short course of methotrexate (MTX) although the optimal usage of these agents remains unclear. Here, we report the results of 55 patients with standard risk leukaemia who have undergone allogeneic transplantation using either bone marrow (n = 48) or G-CSF mobilised peripheral blood stem cells (n = 7) using CsA and MTX for GVHD prophylaxis where the dosage of CsA was regularly adjusted to maintain a trough whole blood level of 95-205 ng/ml for the first 50 days post-transplant. To achieve this level of CsA in the immediate post-transplant period, over 40% of patients required dose adjustments of CsA as a result of sub-therapeutic levels on day +1 post-transplant. The achievement of CsA levels within the therapeutic range was expedited following the introduction of a sliding scale for dose adjustment. With this regimen we have observed a low incidence of acute GVHD with only 11% of patients developing > or =grade II disease. With a median follow-up of 66 months (range 8-132) the probability of relapse is only 6.6%. The disease-free survival probability for all patients was 72% at 5 years. These results demonstrate that effective GVHD prevention with CsA and MTX can be achieved without a high risk of recurrent leukaemia provided that rapid attainment of therapeutic CsA levels is achieved and maintenance within a low therapeutic range may help to maximise this effect.

Autologous reconstitution with BCR-ABL-negative haematopoiesis after T cell-depleted allogeneic BMT for CML

We report a patient with Ph chromosome-positive CML who underwent an HLA-identical T cell-depleted BMT from a sibling donor. DNA polymorphism analysis showed complete donor chimaerism after BMT, followed by mixed chimaerism of granulocytes, natural killer cells and B lymphocytes, with T lymphocytes host-derived at day +120 post BMT. From month +20 haematopoiesis was exclusively of host origin in all cell lineages. RT-PCR was used in order to detect residual disease, but at the time, analysis did not show BCR-ABL transcripts. This case is unusual in that non-malignant stem cells of recipient origin survived the transplant and reconstituted haematopoiesis after BMT. Two years post transplant, no molecular or haematological relapse was documented. The observation that subsequent recipient recovery without molecular relapse implies that, at least in this case, the GVL effect can occur in the absence of donor T cells.