Immune reconstitution following high-dose chemotherapy with stem cell rescue in patients with advanced breast cancer

Immune reconstitution and infectious complications following axicabtagene ciloleucel therapy for large B-cell lymphoma

Chimeric antigen receptor (CAR) T-cell therapy targeting CD19 has significantly improved outcomes in the treatment of refractory or relapsed large B-cell lymphoma (LBCL). We evaluated the long-term course of hematologic recovery, immune reconstitution, and infectious complications in 41 patients with LBCL treated with axicabtagene ciloleucel (axi-cel) at a single center. Grade 3+ cytopenias occurred in 97.6% of patients within the first 28 days postinfusion, with most resolved by 6 months. Overall, 63.4% of patients received a red blood cell transfusion, 34.1% of patients received a platelet transfusion, 36.6% of patients received IV immunoglobulin, and 51.2% of patients received growth factor (granulocyte colony-stimulating factor) injections beyond the first 28 days postinfusion. Only 40% of patients had recovered detectable CD19+ B cells by 1 year, and 50% of patients had a CD4+ T-cell count <200 cells per μL by 18 months postinfusion. Patients with durable responses to axi-cel had significantly longer durations of B-cell aplasia, and this duration correlated strongly with the recovery of CD4+ T-cell counts. There were significantly more infections within the first 28 days compared with any other period of follow-up, with the majority being mild-moderate in severity. Receipt of corticosteroids was the only factor that predicted risk of infection in a multivariate analysis (hazard ratio, 3.69; 95% confidence interval, 1.18-16.5). Opportunistic infections due to Pneumocystis jirovecii and varicella-zoster virus occurred up to 18 months postinfusion in patients who prematurely discontinued prophylaxis. These results support the use of comprehensive supportive care, including long-term monitoring and antimicrobial prophylaxis, beyond 12 months after axi-cel treatment.

Induction of TGF-beta 1, not regulatory T cells, impairs antiviral immunity in the lung following bone marrow transplant

Patients receiving hematopoietic stem cell transplantation or bone marrow transplantation (BMT) as therapy for various malignancies or autoimmune diseases have an increased risk for infectious complications posttransplant, especially in the lung. We have used BMT in mice and murine gammaherpesvirus, gammaHV-68, to study the efficacy of adaptive immune responses post-BMT. Five weeks posttransplant, mice have fully reconstituted their hematopoietic lineages in both the lung and periphery. When challenged with virus, however, BMT mice have a reduced ability to clear lytic virus from the lung. Defective viral control in BMT mice is not related to impaired leukocyte recruitment or defective APC function. Rather, BMT mice are characterized by defective CD4 cell proliferation, skewing of effector CD4 T cells from a Th1 to a Th17 phenotype, and an immunosuppressive lung environment at the time of infection that includes overexpression of TGF-beta1 and PGE(2) and increased numbers of regulatory T cells. Neither indomethacin treatment to block PG synthesis nor anti-CD25 depletion of regulatory T cells improved antiviral host defense post-BMT. Transplanting mice with transgenic bone marrow expressing a dominant-negative TGF-betaRII under the permissive CD4 promoter created mice in which effector CD4 and CD8 cells were unresponsive to TGF-beta1. Mice with TGF-beta1-nonresponsive effector T cells had restored antiviral immunity and improved Th1 responses post-BMT. Thus, our results indicate that overexpression of TGF-beta1 following myeloablative conditioning post-BMT results in impaired effector T cell responses to viral infection.

Significant impairment in immune recovery after cancer treatment

BACKGROUND

Although immunosuppression from cancer adjuvant therapy has been documented, how these suppressed immune responses recover to baseline values after completion of cancer adjuvant therapy has not been studied systematically.

OBJECTIVES

The objective of this study was to examine the probability of immune recovery after cancer adjuvant therapy and the potential impact of cancer adjuvant therapy type and cancer stage on immune recovery in patients with newly diagnosed breast cancer.

METHODS

In a repeated-measures design, immune responses were measured four times in 80 patients with early-stage breast cancer: before and at 2, 6, and 12 months from the beginning of cancer adjuvant therapy. Natural killer cell activity, lymphokine-activated killer cell activity, lymphocyte proliferation, CD subsets (CD4, CD8, and CD56), and cytokines (interferon-gamma, interleukin [IL]-2, IL-4, IL-6, and IL-1alpha) were selected for their relevance to breast cancer. Immune recovery was defined by the level of immune response reaching to and above baseline levels. Data were analyzed using a multivariate generalized linear mixed-model approach.

RESULTS

Delayed immune recovery to pretreatment baseline levels continued to the 12-month time point in all parameters. The percentages of immune recovery ranged from 6% to 76% of the patients, varying among immune parameters. Overall, immune recovery was poorer for interferon-gamma, IL-2, IL-4, lymphocyte proliferation, and natural killer cell activity than was for CD subsets and IL-6. The type of cancer adjuvant therapy, not cancer stage, showed selective influence on immune recovery. Chemotherapy or chemotherapy and radiotherapy combination significantly delayed IL-2 recovery, whereas radiotherapy significantly delayed IL-4 recovery.

DISCUSSION

Immune recovery after breast cancer adjuvant therapy is delayed significantly for an extended time period in numerous immune parameters. The type of cancer adjuvant therapy has selective influence on immune recovery. Future investigations are warranted to elucidate the time course of immune recovery, clinical significance of poor immune recovery, and factors influencing immune recovery to develop potential interventions.

High CD8+ lymphocyte dose in the autograft predicts early absolute lymphocyte count recovery after peripheral hematopoietic stem cell transplantation

Early lymphocyte recovery (ELR) after autologous peripheral hematopoietic stem cell transplantation (ASCT) is an independent predictor for survival in patients with hematological and non-hematological cancers. Sixty-five ASCT for hematological cancers were retrospectively analyzed to identify the factors associated with ELR and to assess the impact of different mobilization regimens on the pre-collection absolute lymphocyte count (ALC). The CD8+ lymphocyte dose in the autograft and the pre-mobilization ALC were independently associated with ELR (P < 0.001 and P = 0.008, respectively). CD8+ lymphocyte doses higher than 0.1 x 10(9)/kg were strongly associated with ELR [P < 0.001, odds ratio 25.22, 95% confidence interval (CI) 4.98-127.69] and this cutoff may be used to predict ELR (P = 0.001, area under the curve 0.75, 95% CI 0.62-0.88). Mobilization with granulocyte colony-stimulating factor (G-CSF) alone, the pre-collection ALC and the number of apheresis sessions were independently associated with the CD8+ lymphocyte dose (P = 0.04, P = 0.001, and P < 0.001, respectively). The number of aphereses was the variable with the strongest correlation to the CD8+ lymphocyte dose (r(s) = 0.68, P < 0.001). Median pre-mobilization ALC was higher than pre-collection ALC in the subgroup of patients without ELR mobilized with chemotherapy followed by G-CSF (1090 vs. 758 lymphocytes/microL; P < 0.001). This reduction was not significant in the subgroup with ELR mobilized with chemotherapy plus G-CSF (1920 vs. 1539/microL, respectively; P = 0.23). These results suggest that the CD8+ lymphocyte dose in the autograft is critical for ELR after ASCT and also demonstrates that mobilization with chemotherapy followed by G-CSF significantly decreases the pre-collection ALC, especially in patients with low pre-mobilization ALC.

Development of T cell-mediated immunity after autologous stem cell transplantation: prolonged impairment of antigen-stimulated production of gamma-interferon

The conditioning regimens for autologous SCT (auto-SCT) lead to impairment of the immune system and concomitant increase in susceptibility to infections. We studied the recovery of cellular immunity by in vitro analysis of T-cell proliferation and cytokine production profiles during the first 15 months after auto-SCT in patients with multiple myeloma and non-Hodgkin's lymphoma. PBMC were collected at 6, 9 and 15 months after transplantation and stimulated with a combination of CD2 and CD28 monoclonal antibodies, with PHA or with tetanus toxoid as recall antigen. A multiplex enzyme linked immunoassay was used to determine levels of Th1 cytokines IL-2, IFN-gamma and tumour-necrosis factor-alpha (TNF-alpha), Th2 cytokines IL-4, IL-5 and IL-13, the regulatory cytokine IL-10 and the proinflammatory cytokines IL-1alpha, IL-1beta, IL-6 and the chemokine IL-8. T-cell proliferation progressively increased from 6 to 15 months after auto-SCT. Overall, cytokine production increased after auto-SCT. Production of Th2 cytokines IL-5 and IL-13 was superior to production of Th1 cytokines IFN-gamma and TNF-alpha. We hypothesize that prolonged impairment of IFN-gamma production might contribute to the relatively high incidence of viral infections after auto-SCT.

Immunity for tumors and microbes after autotransplantation: if you build it, they will (not) come

Relapses after autologous stem cell transplants for hematopoietic malignancies are frequent and post-transplant infections continue to cause significant post-transplant morbidity and even mortality. The post-transplant period is typically characterized by low lymphocyte counts and impaired immune cell function. Early restoration of immune function may contribute to better disease control and enhance protection from infections. Indeed the attainment of a 'minimal residual disease' status following high-dose therapy makes the early post-transplant period ideal for the introduction of antitumor immunotherapy. Attempts to generate immunity against tumor and microbial antigens after autotransplantation have included vaccinations, T cell infusions (both resting and activated) and combinations of vaccinations and adoptive T cell infusions. One successful strategy for generating robust immune responses against microbial antigens was the combination of pre and post-transplant immunizations along with an early (post-transplant) infusion of in vivo vaccine-primed and ex vivo co-stimulated autologous T cells. Whether this or similar strategies will lead to the generation of effective antitumor immunity is unknown. The lessons gained from efforts to rebuild immune system function in the setting of autotransplantation may also be applicable to the problem of restoring immunity in other immunodeficient groups such as patients with cancer or HIV disease and the elderly.

Diminished neo-antigen response to keyhole limpet hemocyanin (KLH) vaccines in patients after treatment with chemotherapy or hematopoietic cell transplantation

Relapse is the most common cause of treatment failure for advanced cancer, even those treated with autologous hematopoietic cell transplantation (HCT). Effective tumor-specific immunotherapy may decrease relapse, however, this will fail if the immune system is unable to respond. We developed a strategy to test immune responses with a single injection of the bona fide neo-antigen KLH. The model was first tested in 37 normal volunteers using three KLH vaccines: Intracel KLH, Biosyn KLH, and Biosyn KLH + adjuvant. Despite finding the immunogenic epitope conserved in both products, intact Intracel KLH induced a better response compared to a purified 350/390 kDA subunit of KLH contained in the Biosyn KLH product. Addition of a synthetic oil adjuvant (Montanide ISA51) restored the response to a single injection of Biosyn KLH. A quantitative readout measured by a KLH-specific cellular and humoral response with isotype switching 1 month after KLH vaccination was established. To test the integrity of the adaptive immune response in cancer patients, we vaccinated 14 patients post-HCT and 19 patients with advanced cancer with KLH vaccines that elicited a 100% response rate in normal volunteers. In marked contrast to normal subjects, both responses were significantly impaired up to 16 months after autologous HCT with an intermediate response in advanced cancer patients. KLH vaccines are safe and require only a single injection to test neo-antigen responses providing an optimal platform for definitive testing of strategies to improve diminished immune recovery after chemotherapy or post-HCT.

T-cell reconstitution and expansion after hematopoietic stem cell transplantation: 'T' it up!

Adoptive immunotherapy is the isolation and infusion of antigen-specific or nonspecific lymphocytes. Adoptive therapy with T cells may have a role in replacing, repairing, or enhancing immune function damaged by cytotoxic therapies, and rapid lymphocyte recovery may improve outcome after autologous and allogeneic stem cell transplantation (SCT). Recently, a plethora of information on the basic mechanisms of T-cell biology and regulation of cellular immune responses has emerged, permitting the development of new forms of adoptive cell therapy. Efficient ex vivo culture method for T-cell subsets affords the possibility of adoptive transfer of T cells engineered with enhanced capacity for central memory, effector cytotoxicity, Th1, Th2, veto cell, and T regulatory functions. Studies show that homeostatic T-cell proliferation is important for effective adoptive immunotherapy and pretreatment with chemotherapy may enhance the effects of infused T cells. Replicative senescence, in part due to telomere erosion, likely limits successful adoptive immunotherapy, though it may be possible to maintain T-cell pools by enforced expression of telomerase. Clinical trials now demonstrate that it is possible to enhance immune reconstitution after SCT with cytokines or infusions of ex vivo costimulated expanded T cells. These data all support the premise that adoptive therapy can accelerate reconstitution of cellular immunity with enhanced antitumor effects following SCT.

Distinct phases in recovery of reconstituted innate cellular-mediated immunity after murine syngeneic bone marrow transplantation

Defects in immune reconstitution after hematopoietic stem cell transplantation confer extreme infection risk on to the transplant recipient. Perturbations in adaptive immune reconstitution have been well characterized, yet defects in reconstituted innate cellular-mediated immunity remain largely unstudied. Recovery in innate effector cells was defined by using an established murine model of autologous bone marrow transplantation. Cytokine induction after cell culture and systemic stimulation with pathogen-associated molecular patterns was also measured for control, transplant-recipient, and irradiated-only animals. Early reconstitution (7 to 14 days) of donor-derived macrophages, dendritic cells, and polymorphonuclear cells was associated with recovery in interleukin (IL)-12p70 and IL-6 production. Later reconstitution (21 days) of natural killer cells was associated with interferon (IFN)-gamma recovery. Hence, splenocyte innate cellular-mediated immunity recovered to normal levels in cellularity and IL-12p70, IFN-gamma, and IFN-alpha production by 21 days after transplantation. In contrast, levels of systemic cytokine production from transplant-recipient and irradiated-only animals were preserved despite incomplete or absent hematopoietic reconstitution. These results suggest that innate immune responses to systemic inflammatory challenges are largely intact after autologous bone marrow transplantation, whereas local innate cellular-mediated immunity within reconstituting lymphoid organs may be impaired. The disparate effects of autologous hematopoietic stem cell transplantation on host immune function may translate to differences in susceptibility to local versus systemic infectious challenges.

Immune restoration following hematopoietic stem cell transplantation: an evolving target

Hematopoietic stem cell transplantation (HSCT) is the definitive cure for many malignant and nonmalignant diseases. However, delays in immune reconstitution (IR) following HSCT significantly limit the success of transplantation and increase the risk for infection and disease relapse in the transplant recipient. Therefore, ways to measure and to manipulate immune recovery following HSCT are emerging and their success depends directly upon an enhanced understanding for the underlying mechanisms responsible for reconstituted immunity and hematopoiesis. Recent discoveries in the activation, function, and regulation of dendritic cell (DC), natural killer (NK) cell, and T-lymphocyte subtypes have been critical in developing immunotherapies used to prevent graft-versus-host disease and to enhance graft-versus-leukemia. For example, regulatory T cells that induce tolerance and NK receptor-tumor ligand disparities that result in tumor lysis are being used to minimize GVHD and tumor burden, respectively. Furthermore, expansion and modulation of immune effector cells are being used to augment hematopoietic and immune recovery and to decrease transplant-related toxicity in the transplant recipient. Specifically, DC expansion and incorporation into antitumor and anti-microbial vaccines is fast approaching application into clinical trials. This paper will review our current understanding for IR following HSCT and the novel ways in which to restore immune function and decrease transplant-related toxicity in the transplant recipient.

Therapeutic potential of a tumor-specific, MHC-unrestricted T-cell receptor expressed on effector cells of the innate and the adaptive immune system through bone marrow transduction and immune reconstitution

T-cell receptor (TCR) with unique major histocompatibility complex (MHC)-unrestricted antigen-binding properties was isolated from a human T-cell clone specific for the tumor antigen MUC1. This TCR binds its epitope on the MUC1 protein without the requirement of processing and presentation. A single-chain Valpha/Vbeta/Cbeta (scTCR) was fused to a CD3 zeta (zeta) chain to allow expression on the surface of cells of the innate (granulocytes, macrophages, natural killer [NK] cells) as well as the adaptive (T and B cells) immune system. To test the ability of the cells of the innate immune system to reject a tumor when provided with a tumor antigen-specific TCR, we reconstituted severe combined immunodeficiency (SCID) mice with bone marrow cells transduced with a retroviral vector encoding this receptor and challenged them with a MUC1-positive human tumor. These mice controlled the growth of the tumor significantly better than the control mice. We performed a similar experiment in immunocompetent mice transgenic for human MUC1. Expression of the TCR on large percentages of cells did not result in infiltration or destruction of tissues expressing MUC1. Reconstituted mice controlled the outgrowth of a MUC1-transfected but not the parental control tumor. scTCR expression appears lifelong, suggesting a successful transduction of the self-renewing stem cells.

Monocyte-mediated T-cell suppression and augmented monocyte tryptophan catabolism after human hematopoietic stem-cell transplantation

T-cell dysfunction after human hematopoietic stem-cell transplantation (HSCT) is generally attributed to intrinsic T-cell defects. Here we show that the characteristic impaired proliferative responses to polyclonal stimulation of post-HSCT peripheral blood mononuclear cells (PB-MCs) were markedly (4-fold) improved by T-cell enrichment. Conversely, addback of post-HSCT monocytes to these enriched T cells dampened their proliferative responses, suggesting that post-HSCT monocytes effectively mediate T-cell suppression. As a mechanism possibly contributing to monocyte-mediated T-cell suppression, we investigated monocyte tryptophan catabolism by indoleamine 2,3-dioxygenase into kynurenine, which has been implicated in regulating T-cell responses. Compared with controls, all post-HSCT monocyte-containing cell cultures (total PBMCs, monocytes, and monocyte/T-cell cocultures), but not monocyte-depleted populations, secreted elevated amounts of kynurenine. Blockade of tryptophan catabolism improved the proliferative responses. The slightly increased kynurenine release and substantial release of neopterin by unstimulated post-HSCT monocytes suggests that they were in a state of continuous activation. Superimposed on this state, stimulation of these cells caused a striking, additional increase (10-fold) in kynurenine release, and they triggered marked apoptosis of autologous post-HSCT T cells. We conclude that the amplified kynurenine release by post-HSCT monocytes, particularly induced upon stimulation, may underlie their suppressor activity, which in turn may contribute to the depressed T-cell immune responses after HSCT.

Fusion cell vaccination of patients with metastatic breast and renal cancer induces immunological and clinical responses

PURPOSE

Dendritic cells (DCs) are potent antigen-presenting cells that are uniquely capable of inducing tumor-specific immune responses. We have conducted a Phase I trial in which patients with metastatic breast and renal cancer were treated with a vaccine prepared by fusing autologous tumor and DCs.

EXPERIMENTAL DESIGN

Accessible tumor tissue was disrupted into single cell suspensions. Autologous DCs were prepared from adherent peripheral blood mononuclear cells that were obtained by leukapheresis and cultured in granulocyte macrophage colony-stimulating factor, interleukin 4, and autologous plasma. Tumor cells and DCs were cocultured in the presence of polyethylene glycol to generate the fusions. Fusion cells were quantified by determining the percentage of cells that coexpress tumor and DC markers. Patients were vaccinated with fusion cells at 3-week intervals and assessed weekly for toxicity, and tumor response was assessed at 1, 3, and 6 months after completion of vaccination.

RESULTS

The vaccine was generated for 32 patients. Twenty-three patients were vaccinated with 1 x 10(5) to 4 x 10(6) fusion cells. Fusion cells coexpressed tumor and DC antigens and stimulated allogeneic T-cell proliferation. There was no significant treatment-related toxicity and no clinical evidence of autoimmunity. In a subset of patients, vaccination resulted in an increased percentage of CD4 and CD8+ T cells expressing intracellular IFN-gamma in response to in vitro exposure to tumor lysate. Two patients with breast cancer exhibited disease regressions, including a near complete response of a large chest wall mass. Five patients with renal carcinoma and one patient with breast cancer had disease stabilization.

CONCLUSIONS

Our findings demonstrate that fusion cell vaccination of patients with metastatic breast and renal cancer is a feasible, nontoxic approach associated with the induction of immunological and clinical antitumor responses.

Prognostic analysis of early lymphocyte recovery in patients with advanced breast cancer receiving high-dose chemotherapy with an autologous hematopoietic progenitor cell transplant

PURPOSE

The purpose of this study was to evaluate the prognostic effect of early posttransplant lymphocyte recovery in patients with advanced breast cancer receiving high-dose chemotherapy with autologous hematopoietic progenitor cell transplantation.

EXPERIMENTAL DESIGN

We analyzed the effect of the absolute lymphocyte count on day +15 posttransplant on freedom from relapse and overall survival in patients with high-risk primary breast cancer or metastatic breast cancer, enrolled between 1990 and 2001 in prospective high-dose chemotherapy trials, using a uniform regimen of cyclophosphamide, cisplatin, and 1,3-bis(2-chloroethyl)-1-nitrosourea.

RESULTS

Four hundred and seventy-six patients (264 high-risk primary breast cancer and 212 metastatic breast cancer patients) were evaluated at median follow-up of 8 years (range, 1.5-11 years). The disease-free survival and overall survival rates in the high-risk primary breast cancer group were 67% and 70%, respectively. Patients with metastatic breast cancer patients had 21.8% disease-free survival and 31.5% overall survival rates. Day +15 absolute lymphocyte count correlated with freedom from relapse (P = 0.007) and overall survival (P = 0.04) in the metastatic breast cancer group, but not in the high-risk primary breast cancer group (P = 0.5 and 0.8, respectively). The prognostic effect of absolute lymphocyte count in metastatic breast cancer was restricted to those patients receiving unmanipulated peripheral blood progenitor cells (P = 0.04). In contrast, absolute lymphocyte count had no significant effect in those metastatic breast cancer patients receiving bone marrow or a CD34-selected product. In multivariate analyses, the prognostic effect of day +15 absolute lymphocyte count in metastatic breast cancer was independent of other predictors, such as disease status, pre-high-dose chemotherapy treatment, number of tumor sites, or HER2.

CONCLUSIONS

Early lymphocyte recovery is an independent outcome predictor in metastatic breast cancer patients receiving high-dose chemotherapy and an autologous peripheral blood progenitor cell transplant. These observations suggest that immune strategies targeting minimal posttransplant residual disease may prove worthwhile.

Resolution of late-onset asthma following high-dose chemotherapy

We describe a patient with moderately severe (British Thorax Society Step IV/V) asthma requiring regular inhaled and oral corticosteroids to control symptoms who experienced resolution of her asthma following high-dose chemotherapy and autologous stem cell transplantation for breast cancer. As far as the authors are aware this is the first reported case.

Cellular immunotherapy after autologous hematopoietic stem cell transplantation: experimental strategies and clinical experiences

Recurrence of disease after autologous hematopoietic stem cell transplantation is at least partly due to contamination of the reinfused transplant with tumor cells, thereby limiting the clinical outcome after transplantation. On the other hand, immunological effector cells are capable of purging bone marrow transplants in vitro and of destroying disseminated tumor cells in vivo. Cellular immunotherapy subsequent to autologous stem cell transplantation is therefore expected to have a major impact on recurrence rates of the disease. In this review, we present various strategies utilizing immunologic effector cells for elimination of disseminated tumor cells and discuss the advantages and limitations of cellular immunotherapy after autologous hematopoietic stem cell transplantation.

Treatment of breast cancer with chemotherapy in combination with filgrastim: approaches to improving therapeutic outcome

Chemotherapy improves disease-free and overall survival in breast cancer, and its benefit is directly related to the percentage of the planned dose that is actually administered. In all current chemotherapeutic regimens, a substantial proportion of patients have reductions and/or delays in dosage due to side effects. In about half such cases, the delays or reductions are related to neutropenia. Overall, approximately 30% of patients have a reduction to less than 85% of the planned dosage. Women aged > or = 50 years are more likely to experience a reduction or delay in dose. Dose-intense regimens (excluding myeloablative high-dose chemotherapy) which increase the dose of chemotherapy or reduce the interval between cycles, or both, are a promising approach now under investigation. The human granulocyte colony-stimulating factor filgrastim reduces the incidence of neutropenia and facilitates adherence to full dose intensity in both standard and dose-intensified regimens. A model based on the first-cycle absolute neutrophil count nadir has been developed and validated to determine which patients should receive filgrastim. A cost benefit associated with the use of filgrastim in patients with breast cancer has been realised. This may lead to a re-evaluation of the current treatment guidelines.

Impact of high-dose chemotherapy on antigen-specific T cell immunity in breast cancer patients. Application of new flow cytometric method

The present study analyses the influence of high-dose chemotherapy (HD) and autologous stem cell transplantation on natural and vaccine-induced specific immunity in breast cancer patients. Peripheral blood was collected from five breast cancer patients at serial time points in connection with treatment and in a follow-up period of 1 year. The frequencies of CD8+ and CD4+ T cells responsive to cytomegalovirus (CMV), varicella zoster virus (VZV), and tetanus in antigen-activated whole blood were determined by flow cytometric analysis of CD69, TNF alpha, IFN gamma and IL-4 expression. Mononuclear cells were labelled with PKH26 dye and the CMV, VZV, and tetanus toxoid-specific proliferation of T cell subpopulations was analysed by flow cytometry. In none of the patients did the treatment result in loss of overall T cell reactivity for any of the antigens. Prior to chemotherapy 5/5 patients possessed TNF alpha expressing T cells specific for CMV, 4/5 for VZV, and 3/5 for tetanus. One year after stem cell transplantation all patients possessed TNF alpha expressing T cells specific for CMV, VZV and tetanus. The highest percentages of cytokine-responding T cells were seen after stimulation with CMV antigen. In general, the lowest reactivity (close to zero) was measured in G-CSF-mobilised blood at the time of leukapheresis. In spite of a continuously reduced CD4 to CD8 ratio after transplantation, recovery of CD4+ T cells usually occurred prior to CD8+ recovery and often to a higher level. The study demonstrates that natural as well as vaccine-induced specific immunity established prior to HD can be regained after stem cell transplantation. These data indicate that introduction of a preventive cancer vaccination in combination with intensive chemotherapy may be a realistic treatment option.

Blood stem cell transplantation for breast cancer: new approaches using pre- peri- post-transplant immunotherapy

Autologous peripheral blood stem cell transplantation (auto-PBSCT) after high dose chemotherapy is usually offered to breast cancer patients carrying a high risk of relapse or having chemosensitive metastatic disease. Whether progression free and overall survival of such patients is improved after auto-PBSCT compared to conventional chemotherapy is a matter of debate. Currently available results of randomised trials could not uniformly prove or disprove auto-PBSCT being advantageous. Yet such studies have not employed any manipulation of the stem cell graft or any post-transplant immunomodulation exploiting the unique immunological environment for tumour eradication which exists only after auto-PBSCT. Preliminary data have discussed the ex vivo and in vivo generation of cytotoxic effector cells employing IL-2 and/or IFN-alpha/gamma in the auto-PBSCT setting. Other cytokines such as IL-12, IL-15 and prolactin have likewise been considered. Several anticancer vaccine protocols after auto-PBSCT are ongoing using monovalent vaccines or anti-idiotypic antibodies. Polyvalent anticancer vaccines, cytokine secreting tumour cells, tumour pulsed or hybridised dendritic cells (DC) enhanced with cytokines are studied. Monoclonal antibodies (mAb) could assist: unlabelled for pretransplant exvivo purging, post-transplant for enhancing antibody-dependent cell mediated cytotoxicity (ADCC) or radioimmunoconjugated as an additive cytotoxic part of the conditioning regimen. Autologous graft versus host induction and allogeneic stem cell transplantation (probably with non-myeloablative conditioning followed by donor lymphocyte infusions) are other approaches. Evaluation of successful combinations, optimal dosages and appropriate timing schedules is the subject of future investigations. Since breast cancer patients belong to countless subgroups, a large number of protocols need to be addressed in order to avoid over treatment and prevent relapse.

Prolonged survival associated with early lymphocyte recovery after autologous hematopoietic stem cell transplantation for patients with metastatic breast cancer

Early absolute lymphocyte count (ALC) recovery at day 15 post-autologous stem cell transplantation (ASCT) is a powerful prognostic indicator for survival in multiple myeloma and non-Hodgkin's lymphoma. The relationship of ALC with clinical outcomes in metastatic breast cancer is unknown. We evaluated all 29 patients with metastatic breast cancer who underwent ASCT at the Mayo Clinic, Rochester, Minnesota, from 1994 to 1999. The ALC threshold was set at 500 cells/microl on day 15 post-ASCT based on previous experience with hematologic malignancies. All patients were followed for a minimum of 2 years or until death, with a median follow-up for living patients of 2.25 years. Of the 29 patients, 17 have died with disease progression, two are alive and have progressed, and 10 are alive without progression. The median overall and progression-free survival times were significantly better for the 20 patients with ALC > or = 500 cells/microl compared with the nine patients with ALC <500 cells/microl (not reached vs 14 months, P < 0.0001; 24 vs 7 months, P < 0.0015, respectively). In conclusion, ALC > or = 500 cells/microl on day 15 post-ASCT was associated with significantly better survival in patients with metastatic breast cancer, suggesting the importance of early immune recovery post-ASCT in these patients.

Activation-induced T cell apoptosis by monocytes from stem cell products

We recently found that mobilized peripheral blood stem cell (PSC) products (from both cancer patients and normal donors) contain high levels of CD14+ monocytes, which can inhibit the proliferation of allogeneic and autologous T cells. We found in our studies that using CD14+ monocytes from mobilized PSC products (from normal and cancer patient donors), normal apheresis products or normal peripheral blood (PB) can affect lymphocyte function and apoptosis-dependent T cell activation. However, it appears that the apoptosis is dependent on the frequency of monocytes, which is increased by both mobilization and apheresis. Both phytohemagglutinin (PHA)- and interleukin (IL)-2-induced proliferation of steady-state peripheral blood mononuclear cells (PBMC) were markedly inhibited by co-culture with irradiated CD14+ monocytes, although inhibition was significantly greater with PHA than with IL-2 stimulation. IL-2 (predominately CD56+ NK cells) or anti-CD3 monoclonal antibody (mAb) and IL-2-expanded lymphocytes (activated T cells) were inhibited by PSC monocytes to a significantly greater level as compared to steady-state lymphocytes. Indeed, no inhibition of T cell proliferation was observed when lymphocytes were co-cultured in the absence of mitogenic or IL-2 stimulation. In contrast, an increased proliferation was observed in co-cultures of CD14+ monocytes and steady-state or activated lymphocytes without mitogenic stimulation. Cell cycle analysis by flow cytometry revealed a significant increase in hypodiploid DNA, in a time-dependent manner, following co-culture of monocytes and PBMC in PHA, suggesting that T cell apoptosis occurred during PHA-induced activation. These results demonstrate that PSC-derived monocytes inhibit T cell proliferation by inducing the apoptosis of activated T cells and NK cells, but not steady-state cells. This suggests a potential role for monocytes in the induction of peripheral tolerance following stem cell transplantation.

Interim analysis of the use of the anti-idiotype breast cancer vaccine 11D10 (TriAb) in conjunction with autologous stem cell transplantation in patients with metastatic breast cancer

The anti-idiotype monoclonal antibody breast cancer vaccine 11D10 (TriAb) was administered before and after autologous stem cell transplantation (ASCT) in 45 patients with metastatic breast cancer whose disease was responsive to conventional chemotherapy. Evidence of a positive anti-anti-idiotype antibody (Ab3) humoral response was noted at a median of 1.76 months post-ASCT (range, before ASCT-6 months) with this strategy. Maximal Ab3 levels and idiotype-specific T-cell proliferative responses were observed at a median of 3 and 4 months, respectively, after ASCT. The achievement of rapid immune responses after ASCT, during a known period of decreased immunoresponsiveness, opens the possibility of an additional antitumor effect at a time when the tumor burden is relatively small. Moreover, in this interim analysis, patients with the most vigorous humoral and cellular immune responses had a significant improvement in progression-free survival. Further follow-up and evaluation of this approach is warranted.

Mechanisms of immune dysfunction in stem cell transplantation

High dose therapy (HDT) and stem cell transplantation (SCT) results in alterations in the immunologic network, thymic re-education and the induction of peripheral tolerance. The changes to the immunoregulatory cascade and tolerance induction associated with autotransplants have been investigated in a series of studies focused on leukocyte reconstitution and function following HDT and autologous SCT. In these studies, we observed a significant decrease in the CD4:CD8 T cell ratio post-transplantation compared to normal peripheral blood (PB) donors due to a decrease in CD4+ cells. In addition, T cell function (phytohemagglutinin (PHA) mitogenesis) was consistently depressed compared to samples obtained from normal PB donors. The loss of T cell function was associated with an increased frequency of circulating monocytes, their expression of Fas ligand (FasL) and a high frequency of apoptotic CD4+ T cells. Indeed, 28-51% of circulating CD4+ T cells were observed to be apoptotic during the first 100 days following HDT and SCT. These studies suggest that 'primed' or activated Fas+ CD4+ lymphocytes interact with FasL+ monocytes, resulting in apoptosis, leading to the preferential deletion of CD4+ T cells, a decrease in the CD4:CD8 T cell ratio and depressed T cell function. Further, as discussed herein, the T cells are activated with a predominantly type 2 phenotype, which may also contribute to the maintenance of the immunosuppressive condition. Therefore, there is the potential to regulate immune recovery by stem cell product manipulation or post-transplantation cytokine administration.