Development of adaptive immune effector therapies in solid tumors

State-of-the-art treatment strategies have drastically ameliorated the outcome of patients affected by cancer. However, resistant and recurrent solid tumors are generally nonresponsive to conventional therapies. A central factor in the sequence of events that lead to cancer is an alteration in antitumor immune surveillance, which results in failure to recognize and eliminate the transformed tumor cell. A greater understanding of the dysregulation and evasion of the immune system in the evolution and progression of cancer provides the basis for improved therapies. Targeted strategies, such as T-cell therapy, not only generally spare normal tissues, but also use alternative antineoplastic mechanisms that synergize with other therapeutics. Despite encouraging success in hematologic malignancies, adaptive cellular therapies for solid tumors face unique challenges because of the immunosuppressive tumor microenvironment, and the hurdle of T-cell trafficking within scarcely accessible tumor sites. This review provides a brief overview of current cellular therapeutic strategies for solid tumors, research carried out to increase efficacy and safety, and results from ongoing clinical trials.

Extracellular NK histones promote immune cell anti-tumor activity by inducing cell clusters through binding to CD138 receptor

Background

Natural killer (NK) cells are important anti-tumor cells of our innate immune system. Their anti-cancer activity is mediated through interaction of a wide array of activating and inhibitory receptors with their ligands on tumor cells. After activation, NK cells also secrete a variety of pro-inflammatory molecules that contribute to the final immune response by modulating other innate and adaptive immune cells. In this regard, external proteins from NK cell secretome and the mechanisms by which they mediate these responses are poorly defined.

Methods

TRANS-stable-isotope labeling of amino acids in cell culture (TRANS-SILAC) combined with proteomic was undertaken to identify early materials transferred between cord blood-derived NK cells (CB-NK) and multiple myeloma (MM) cells. Further in vitro and in vivo studies with knock-down of histones and CD138, overexpression of histones and addition of exogenous histones were undertaken to confirm TRANS-SILAC results and to determine functional roles of this material transferred.

Results

We describe a novel mechanism by which histones are actively released by NK cells early after contact with MM cells. We show that extracellular histones bind to the heparan sulfate proteoglycan CD138 on the surface of MM cells to promote the creation of immune-tumor cell clusters bringing immune and MM cells into close proximity, and thus facilitating not only NK but also T lymphocyte anti-MM activity.

Conclusion

This study demonstrates a novel immunoregulatory role of NK cells against MM cells mediated by histones, and an additional role of NK cells modulating T lymphocytes activity that will open up new avenues to design future immunotherapy clinical strategies.

Changing prognosis in paroxysmal nocturnal haemoglobinuria disease subcategories: an analysis of the International PNH Registry

BACKGROUND

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare disease. Although much progress has been made in the understanding of the pathophysiology of the disease, far less is known with respect to the clinical outcomes of patients with PNH. Few retrospective studies provide survival estimates, and even fewer have explored the clinical heterogeneity of the disease. Haemolytic and aplastic anaemia (AA) forms of the disease have been recognised as main disease categories, with the haemolytic form being associated with the worst prognosis by the largest studied cohort some years ago.

AIMS

To describe mortality and causes of death in PNH overall and by PNH classification and to evaluate risk factors associated with mortality.

METHODS

We analysed data of 2356 patients enrolled in the International PNH Registry with multivariate analyses, using time-dependent covariates. Patients were classified into haemolytic, AA/PNH syndrome or intermediate PNH.

RESULTS

Overall, 122 (5.2%) patients died after enrolment, the incidence according to subcategories being 5.1, 11.7, 2.0 and 4.8% for patients with haemolytic PNH, AA-PNH, intermediate and insufficient data respectively. Older age and decreased performance status also affected survival in multivariate analysis. Improved outcome of patients with haemolytic PNH suggests that eculizumab treatment in PNH may be associated with improved survival.

CONCLUSION

A detailed analysis of clinical presentations and causes of death in patients with PNH, overall and by disease subcategories, provide evidence that in the current era, patients with haemolytic PNH are no longer those who harbour the worst prognosis. This finding differs sharply from what has been previously reported.

Allogeneic hematopoietic SCT in multiple myeloma: long-term results from a single institution

The role of allogeneic hematopoietic SCT (allo-HCT) in multiple myeloma (MM) remains controversial. A total of 58 patients received an allo-HCT (25 of them with myeloablative conditioning-allo-MAC-and 33 with reduced-intensity conditioning-allo-RIC) at our institution over a 28-year period. The CR rate for allo-MAC was 36%. The incidence of grade III-IV acute GVHD (aGVHD) and chronic GVHD (cGVHD) was 28% and 39%, respectively The TRM at any time was 60% and the main causes of death were aGVHD or infectious complications not directly related to GVHD. The estimated PFS and OS at 15 years were 8% and 15%, respectively. The CR rate with allo-RIC was 45%. The incidence of grade III-IV aGVHD and cGVHD were 24% and 41%, respectively. The TRM at any time was 33% and was mainly related to aGVHD. The estimated PFS and OS at 5 years were 22% and 38%, respectively. Despite its high TRM, a proportion of patients with high-risk myeloma (early relapse and newly diagnosed ultrahigh risk) may obtain long-term disease control with allo-HCT. New approaches aimed at decreasing the incidence of aGVHD, and consequently to decrease the TRM, are needed.

Transmissible cytotoxicity of multiple myeloma cells by cord blood-derived NK cells is mediated by vesicle trafficking

Natural killer cells (NK) are important effectors of anti-tumor immunity, activated either by the downregulation of HLA-I molecules on tumor cells and/or the interaction of NK-activating receptors with ligands that are overexpressed on target cells upon tumor transformation (including NKG2D and NKP30). NK kill target cells by the vesicular delivery of cytolytic molecules such as Granzyme-B and Granulysin activating different cell death pathways, which can be Caspase-3 dependent or Caspase-3 independent. Multiple myeloma (MM) remains an incurable neoplastic plasma-cell disorder. However, we previously reported the encouraging observation that cord blood-derived NK (CB-NK), a new source of NK, showed anti-tumor activity in an in vivo murine model of MM and confirmed a correlation between high levels of NKG2D expression by MM cells and increased efficacy of CB-NK in reducing tumor burden. We aimed to characterize the mechanism of CB-NK-mediated cytotoxicity against MM cells. We show a Caspase-3- and Granzyme-B-independent cell death, and we reveal a mechanism of transmissible cell death between cells, which involves lipid-protein vesicle transfer from CB-NK to MM cells. These vesicles are secondarily transferred from recipient MM cells to neighboring MM cells amplifying the initial CB-NK cytotoxicity achieved. This indirect cytotoxicity involves the transfer of NKG2D and NKP30 and leads to lysosomal cell death and decreased levels of reactive oxygen species in MM cells. These findings suggest a novel and unique mechanism of CB-NK cytotoxicity against MM cells and highlight the importance of lipids and lipid transfer in this process. Further, these data provide a rationale for the development of CB-NK-based cellular therapies in the treatment of MM.

Differences in cytomegalovirus replication quantified using quantitative polymerase chain reaction and antigenemia after allogeneic stem cell transplantation

Fifty percent of allogeneic stem cell recipients develop cytomegalovirus (CMV) infection in the first 100 days posttransplantation. Various methods have been used to determine CMV infections, including antigenemia assay and real-time polymerase chain reaction (RT-PCR). Although antigenemia assay has been used more frequently, this technique is less sensitive than RT-PCR. In contrast, RT-PCR has a low positive predictive value for CMV end-organ disease. Cytomegalovirus infections were analyzed in 41 peripheral blood samples from allogeneic stem cell recipients using both antigenemia assay and RT-PCR; results were discordant in 36.6% of patients. Although the antigenemia assay detected CMV replication in 29.2% of cases, RT-PCR was positive in 65.8%. In 83.3% of patients, results detected using the antigenemia assay were delayed by a median (range) of 5 (2-20) weeks compared with positive RT-PCR results. Within the first 100 days posttransplantation, higher levels of viral replication measured using RT-PCR were observed in patients with vs without antigenemia. In addition, in patients with antigenemia, viral load was significantly higher before day 100 than after (P=.01 and P=.008, respectively) compared with those without antigenemia.

Clinical utility of real-time polymerase chain reaction to quantify cytomegalovirus replication in allogeneic stem cell transplant recipients with different prevention strategies

Cytomegalovirus (CMV) end-organ disease is a serious, frequent complication after allogenic stem cell transplantation (Allo-SCT). There are two prevention strategies: universal prophylaxis and preemptive therapy. Preemptive therapy is administered based on the results of sensitive techniques that detect the viral infection. We analyzed 41 peripheral blood Allo-SCT recipients: 34 received prophylaxis and seven preemptive treatment. Viral infections determined using real-time polymerase chain reaction (RT-PCR) assays occurred at an overall incidence of 65.8%. The viral loads quantified by RT-PCR were compared among the prophylaxis versus the preemptive group. Overall, the median viral load was significantly higher in the preemptive compared with the prophylaxis group (P=.002). Furthermore, within the first 100 days posttransplantation, viral load values were higher among patients undergoing preemptive therapy (P=.009).

Results of the EBMT activity survey 2005 on haematopoietic stem cell transplantation: focus on increasing use of unrelated donors

This EBMT activity report documents the haematopoietic stem cell transplantation (HSCT) activity in Europe in 2005. It provides numbers of HSCT by indication, donor type and stem cell source, lists the new practice of planned double transplants with allogeneic after autologous HSCT and concentrates on the increasing role of unrelated transplants over the last years. In 2005, there were 24,168 first HSCT, 8890 allogeneic (37%), 15,278 autologous (63%) and 3773 additional re- or multiple transplants reported from 597 centres in 43 participating countries. Main indications were leukaemias (7404 (31%; 82% allogeneic)); lymphomas (13,825 (57%; 89% autologous)); solid tumours (1655 (7%; 92% autologous)) and non-malignant disorders (1131 (5%; 93% allogeneic)). A total of 671 planned allogeneic after autologous HSCT were reported; the majority for myeloma (52%), lymphoma (28%) and acute myeloid leukaemia (11%). Compared to 2004, there was a 20% increase in allogeneic HSCT; numbers of autologous HSCT remained constant. The most noticeable increase was in unrelated HSCT, which comprise 41% of all allogeneic HSCT. Unrelated HSCT were preferentially performed for leukaemias and in countries with high income according to World Bank criteria. These data illustrate the current experience in Europe and form the basis for patient counselling and decisions making at health care institutions.

EBMT activity survey 2004 and changes in disease indication over the past 15 years

This fifteenth annual European Group for Blood and Marrow Transplantation activity report lists the transplant activity in Europe in 2004 and documents the changes in indication over the past 15 years. In 2004, there were 22 216 first hematopoetic stem cells (HSCT), 7407 allogeneic (33%), 14 809 autologous (67%) and 4378 additional re- or multiple transplants reported from 592 centres in 38 European and five affiliated countries. Main indications were leukemias (7045 (32%; 78% allogeneic)); lymphomas (12 310 (55%; 94% autologous)); solid tumors (1759 (8%; 93% autologous)) and nonmalignant disorders (1015 (5%; 92% allogeneic)). In comparison, 145 teams from 20 countries performed 4234 HSCT (2137 allogeneic, 50%; 2097 autologous, 50%) in 1990. The overall increase was accompanied by major changes. Stem cell source changed from bone marrow to peripheral blood. More than one-third of allogeneic HSCT are now from unrelated donors. Reduced intensity conditioning is employed for one-third of allogeneic HSCT. Leukemias for allogeneic and lymphoproliferative disorders for autologous HSCT continue to increase. The decline in HSCT for chronic myeloid leukemia appears to level off for the first time since 1999. These data are informative for patient counselling and decision making for health care professionals.

G-CSF increases the number of peripheral blood dendritic cells CD16+ and modifies the expression of the costimulatory molecule CD86+

Dendritic cells (DC) play a key role in initiating immune reactions after allogeneic stem cell transplantation. The two main peripheral blood DC populations are myeloid (DC1) and lymphoplasmacytoid (DC2). A new subset of myeloid DC, expressing CD16, has been identified. We analyzed the number and CD86 expression of DC subsets in peripheral blood of 18 healthy donors, before and after granulocyte colony-stimulating factor (G-CSF) and in the inoculum of allogeneic peripheral blood transplants (allo-PBT; n=100) and allogeneic bone marrow transplants (allo-BMT; n=22). Granulocyte colony-stimulating factor administration increased the median number of DC1 (P=0.0007), of DC2 (P<0.0001) and of DC CD16+ (P=0.0001). Granulocyte colony-stimulating factor administration was also associated with a significant decrease of CD86 expression on DC1 (P=0.0003) and with a trend for an increase on DC CD16+ (P=0.07). Recipients of allo-PBT received similar quantities of DC1 and higher doses of DC2 and DC CD16+ than recipients of allo-BMT (P=0.5; P=0.0001; P<0.0001, respectively). Granulocyte colony-stimulating factor modifies the number of DC in peripheral blood and the expression of the costimulatory molecule CD86. This resulted in a different composition of DC2 and especially of DC CD16+ in the harvests, which might explain some of the differences observed in allogeneic reactions after allo-PBT with respect to allo-BMT.

Allogeneic and autologous transplantation for haematological diseases, solid tumours and immune disorders: definitions and current practice in Europe

The Accreditation Subcommittee of the EBMT regularly publishes special reports on current practice of haemopoietic stem cell transplantation for haematological diseases, solid tumours and immune disorders in Europe. Major changes have occurred since the first report was published in 1996. Haemopoietic stem cell transplantation today includes grafting with allogeneic and autologous stem cells derived from bone marrow, peripheral blood and cord blood. With reduced intensity conditioning regimens in allogeneic transplantation, the age limit has increased, permitting the inclusion of older patients. New indications have emerged such as autoimmune disorders and AL amyloidosis for autologous, and solid tumours for allogeneic transplants. The introduction of alternative therapies has challenged well-established indications such as imatinib for chronic myeloid leukaemia. An updated report with revised tables and operating definitions is presented here.

Change in stem cell source for hematopoietic stem cell transplantation (HSCT) in Europe: a report of the EBMT activity survey 2003

This EBMT activity survey presents the status of hematopoietic stem cell transplantation (HSCT) in Europe 2003 and focuses on changes in stem cell source over the last decade. There were 21 028 first HSCT, 7091 allogeneic (34%), 13 937 autologous (66%) and 4179 additional re- or multiple transplants reported from 597 centers in 42 European countries in the year 2003. Main indications were leukemias (6613 (31%; 78% allogeneic)); lymphomas (11 571 (55%; 93% autologous)); solid tumors (1792 (9%; 92% autologous)) and nonmalignant disorders (898 (5%; 93% allogeneic)). In 1991, the vast majority of autologous and all allogeneic HSCT were still bone marrow (BM) transplants. Stem cell source changed rapidly to peripheral blood (PB) for autologous HSCT between 1992 and 1996. In 2003, 97% of autologous HSCT were PB derived. The change to PB for allogeneic HSCT followed 3 years later and occurred at a lower rate. In 2003, 65% of all allogeneic HSCT were PB derived. The change in stem cell source was not homogeneous. It was associated with donor type, main diagnosis, disease stage and it differed between European countries. In 2003, bone marrow remains a significant source of stem cells in some European countries for autologous HSCT and for nonmalignant disorders in allogeneic HSCT.

Transmission of donor illness by stem cell transplantation: should screening be different in older donors?

With increasing donor age, the potential of transmitting diseases from donor to recipient reaches new dimensions. Potentially transmittable diseases from donors include infections, congenital disorders, and acquired illnesses like autoimmune diseases or malignancies of hematological or nonhematological origin. While established nonmalignant or malignant diseases might be easy to discover, early-stage hematological diseases like CML, light-chain multiple myelomas, aleukemic leukemias, occult myelodysplastic syndromes and other malignant and nonmalignant diseases might not be detectable by routine screening but only by invasive, new and/or expensive diagnostic tests. In the following article, we propose recommendations for donor work-up, taking into consideration the age of the donors. In contrast to blood transfusions, stem cells from donors with abnormal findings might still be acceptable for HCT, when no other options are available and life expectancy is limited. This issue is discussed in detail in relation to the available donor and stem cell source. Finally, the recommendations presented here aim at harmonized worldwide work-up for donors to insure high standard quality.

Haematopoietic stem cell transplantation (HSCT) in Europe 2002. Changes in indication and impact of team density. A report of the EBMT activity survey

This 2002 European Group for Blood and Marrow Transplantation (EBMT) activity survey concentrates on current status, increase and decrease in haematopoietic stem cell transplantation (HSCT) activity in Europe and investigates the association of transplant rates with team density. In 2002, there were 20 207 HSCT, 6915 allogeneic (34%), 13 292 autologous (66%) and 3947 additional re- or multiple transplants collected from 586 centres in 39 European countries. Main indications were leukaemias (6523 (32%; 76% allogeneic)); lymphomas (10 760 (53%; 92% autologous)); solid tumours (1913 (9%; 92% autologous)) and nonmalignant disorders (874 (4%; 92% allogeneic)). Compared to 2001, there were increases (>10%) for AML, ALL 1st CR, CML not 1st cP, MDS, SAA and CLL in allogeneic HSCT and for MDS, Ewing's sarcoma, soft-tissue sarcoma and ovarian cancer in autologous HSCT. Decreases (>10%) were observed in autologous HSCT for acute leukaemias beyond 1st CR, CML cP, glioma, breast cancer and lung cancer. Correlation of transplant rates (number of transplants per 10 million inhabitants) with team density (number of transplant teams per 10 million inhabitants) suggests different diffusion patterns for autologous compared to allogeneic HSCT. These data describe current practice for blood and marrow transplantation in Europe and give some hints about mechanisms involved in HSCT rates.

Elderly age and prior autologous transplantation have a deleterious effect on survival following allogeneic peripheral blood stem cell transplantation with reduced-intensity conditioning: results from the Spanish multicenter prospective trial

Over a 3-year period, 145 patients ineligible for myeloablative conditioning underwent reduced-intensity conditioning (RIC) hematopoietic stem cell transplantation (SCT) from an HLA-identical sibling in a prospective study. The median age was 54 years, 88 patients were male and 61 patients were beyond the early-intermediate phase of their disease. The 100-day probability of developing grade II-IV acute graft-versus-host disease (GVHD) was 34%, and the 1-year probability of developing chronic extensive GVHD was 41%. The 1-year probabilities of transplant-related mortality (TRM), overall (OS) and progression-free survival were 20, 60 and 52%, respectively. Multivariate analyses found a better OS in: (i) patients <60 years; and (ii) recipients of a first SCT; and a higher TRM in: (i) age >60 years, (ii) recipients of a prior autologous SCT, and (iii) an ECOG performance status >1. The 1-year TRM in patients with 0 or 1 and >2 of the above-mentioned adverse prognostic factors were 17 vs 53%, respectively (P<0.001). In summary, our study shows that elderly patients have a higher TRM following an RIC protocol. However, age by itself should not preclude these RIC transplants, since TRM appears to be unacceptably high only in the presence of additional adverse factors.

Hematopoetic stem cell transplantation for solid tumors in Europe

BACKGROUND

Hematopoetic stem cell transplants (HSCT) are discussed as treatment options for patients with solid tumors. Transplant numbers have changed substantially over the last decade, few controlled studies are available and different opinions prevail. Objective information on current practice is needed.

PATIENTS AND METHODS

Data from 27 902 HSCT for solid tumors (2% allogeneic, 98% autologous), collected by the European Group for Blood and Marrow Transplantation (EBMT) activity survey from 1991 to 2002 were used to assess trends, transplant rates and coefficient of variation of transplant rates in Europe.

RESULTS

Transplant numbers increased from 536 in 1991 to 4154 in 1997 and decreased to 1913 in 2002. Indications were neuroblastoma (2504 HSCT; 9%), glioma (662 HSCT; 2%), soft tissue sarcoma (1253 HSCT; 4%), germ cell cancer (3291 HSCT; 12%), breast cancer (13 524 HSCT; 48%), Ewing's sarcoma (1896 HSCT; 7%), lung cancer (387 HSCT; 1%), ovarian cancer (845 HSCT; 3%) and other solid tumors (3540 HSCT; 14%). Allogeneic cells were used in <20 cases up to 1997; since then allogeneic HSCT increased to 159 in 2002, mainly for renal cell carcinoma. Low coefficients of variation in transplant rates (<60%) are observed for Ewing's sarcoma (<56.5%), suggesting consensus for this indication.

CONCLUSIONS

These data give an overview on current practice of HSCT for solid tumors in Europe. They provide objective information for health-care providers and patient counselling.