Bortezomib after dose-reduced allogeneic stem cell transplantation for multiple myeloma to enhance or maintain remission status

Allogeneic stem cell transplantation in multiple myeloma: is there still a place?

The introduction of novel agents dramatically improved response and outcomes of multiple myeloma (MM) and led to a sharp decline in the use of allogeneic hematopoietic stem-cell transplantation (allo-HSCT). Thus, recent guidelines do not recommend anymore allo-HSCT as consolidation in the first-line treatment of newly diagnosed MM, even in high-risk patients. In a relapsed/refractory setting, allo-HSCT is not routinely recommended but should only be performed within clinical trials in young and high-risk patients. Nonetheless, allo-HSCT still represents a potential curative approach that has been used for decades in the treatment of MM and plasma cell neoplasms with favorable results and may still represent a treatment option for carefully selected patients. Despite that promising results were obtained with CAR T-cell therapies and bispecific antibodies in triple- and penta-exposed/refractory MM, these patients will inevitably relapse. To date, less is known about outcomes of allo-HSCT in patients exposed to novel immunotherapeutic drugs. Therefore, allo-HSCT could represent a reasonable treatment choice for younger and high-risk patients who have relapsed after CAR T-cell therapies and bispecific antibodies as well as an alternative for patients not eligible to these treatments and in those countries where immunotherapies are not yet available. In the choice of conditioning, reduced intensity conditioning regimens are currently recommended for the lower toxicity and mortality. Moreover, the use of alternative donors, particularly haploidentical, has progressively increased in last years with results comparable to full matched donors. Finally, post-transplantation maintenance strategies are encouraged whenever feasible.

Bortezomib Maintenance After Allogeneic Transplantation in Newly Diagnosed Myeloma Patients Results in Decreased Incidence and Severity of Chronic GVHD

Allogeneic hematopoietic cell transplantation (HCT) has curative potential in myeloma but remains hampered by high rates of relapse and chronic graft-versus-host disease (GVHD). We hypothesized that bortezomib (BTZ) as maintenance therapy after allo HCT could not only decrease the incidence of relapse but also the incidence and severity of chronic GVHD. The primary endpoint of this study was to determine whether BTZ maintenance decreases the incidence and severity of chronic GVHD using National Institutes of Health (NIH) criteria. The secondary endpoints were to determine the immunosuppression burden, organ involvement and survival (overall survival, progression-free survival) in patients either receiving or not receiving BTZ. In this retrospective study, we compared the outcome of 46 myeloma patients who received BTZ after upfront tandem auto-allo HCT between 2008 and 2020 to 61 patients without maintenance. We explored the impact of BTZ maintenance on incidence and severity of chronic GVHD using the 2014 NIH criteria. At 2 years, incidences of overall (61.2% versus 83.6%; P = .001), and moderate/severe chronic GVHD (44.5% versus 77.0%; P = .001) were significantly lower in BTZ recipients who had less mouth (43% versus 67%; P = .018) and eyes (9% versus 41%; P = .001) involvement at initial diagnosis. We report a lower use of systemic steroids (45.1% versus 76.4%; P < .001), mycophenolate mofetil (15.5% versus 28.2%; P = .031) and tacrolimus (34.5% versus 70.6%; P < .001) in BTZ recipients. Probability of being alive and off systemic immunosuppressants at 3 years was 77% in BTZ recipients and 56% in controls (P = .046). To date, there is no difference in survival between both groups. In summary, BTZ maintenance improved incidence and severity of chronic GVHD and should be considered as a valid option in myeloma patients receiving upfront tandem auto-allo HCT.

PLK4 inhibitor plus bortezomib exhibits a synergistic effect on treating multiple myeloma via inactivating PI3K/AKT signaling

OBJECTIVE

The anti-tumor effect of polo-like kinase 4 (PLK4) inhibitor has been explored in several neoplasms, while its synergy with bortezomib in multiple myeloma (MM) remains elusive. Hence, the present study aimed to investigate the effect of PLK4 inhibitor on the sensitivity of MM to bortezomib treatment and its underlying mechanism.

METHODS

MM cell lines (RPMI-8226 and U266) were cultured in different concentrations of CFI-400945 (PLK4 inhibitor), bortezomib, or their combination. Subsequently, 740 Y-P (PI3K activator) was added in the combination of CFI-400945 and bortezomib. Besides, cell viability and apoptosis were measured by CCK-8 reagent and TUNEL apoptosis kit, separately; meanwhile, western blot was carried out for detecting PLK4, p-PI3K, PI3K, p-AKT, and AKT.

RESULTS

CFI-400945 and bortezomib decreased the cell viability in dose-dependent manners in MM cell lines, respectively. The combination of different concentrations of CFI-400945 and bortezomib reduced cell viability compared with monotherapy in MM cell lines (all P < 0.05). Interestingly, 200 nM CFI-400945 and 4 nM bortezomib showed the maximum synergy in MM cell lines. Furthermore, 200 nM CFI-400945 plus 4 nM bortezomib showed a better effect on decreasing cell viability and promoting cell apoptosis than CFI-400945 or bortezomib monotherapy in MM cells cell lines (all P < 0.05). Moreover, 740 Y-P alleviated the effect of bortezomib and CFI-400945 on PI3K/AKT signaling, cell viability, and apoptosis in MM cell lines.

CONCLUSIONS

PLK4 inhibitor plus bortezomib shows synergy in decreasing cell viability and enhancing cell apoptosis via repressing PI3K/AKT signaling in MM.

Allogeneic Stem Cell Transplantation in Patients with High-Risk Multiple Myeloma: Utopia or Continuous Challenge in Aiming for Cure?

OPINION STATEMENT

Nowadays, several novel agents have been introduced in the treatment of multiple myeloma, not only resulting in high response rates and prolonged survival but also offering good quality of life. However, the potential of cure, especially for patients with advanced or unfavorable disease features, remains elusive. Allogeneic hematopoietic stem cell transplantation, based mainly on the graft vs. myeloma effect, can offer prolonged disease control and probability of cure but unfortunately at the cost of considerable transplant-related toxicity rates. Therefore, the role of allogeneic hematopoietic stem cell transplantation in the treatment of multiple myeloma has been called into question. Recently, several studies, particularly those with long-term follow-up, demonstrated a trend of survival superiority for allografted patients with high-risk disease. These data fuel again the interest in allogeneic stem cell transplantation for selected patients with high-risk multiple myeloma, especially if the high remission rates which can be achieved with the currently used treatment protocols could be long-life sustained through the additional exploitation of the long-lasting anti-multiple myeloma effect, originating from the allograft.

Long-term outcome after allogeneic stem cell transplantation in multiple myeloma

The role of allogeneic hematopoietic stem cell transplantation (allo-SCT) in multiple myeloma is controversial. We analyzed the results of 205 patients transplanted in one center during 2000–2017. Transplantation was performed on 75 patients without a previous autologous SCT (upfront-allo), on 74 as tandem transplant (auto-allo), and on 56 patients after relapse. Median overall survival (OS) was 9.9 years for upfront-allo, 11.2 years for auto-allo, and 3.9 years for the relapse group (p = 0.015). Progression-free survival (PFS) was 2.4, 2.4, and 0.9 years, respectively (p < 0.001). Non-relapse mortality at 5 years was 8% overall, with no significant difference between the groups. Post-relapse survival was 4.1 years for upfront-allo and auto-allo, and 2.6 years for the relapse group (p = 0.066). Survival of high-risk patients was reduced. In multivariate analysis, the auto-allo group had improved OS and chronic graft-versus-host disease was advantageous in terms of PFS, OS, and relapse incidence. Late relapses occurred in all groups. Allo-SCT resulted in long-term survival in a small subgroup of patients. Our results indicate that auto-allo-SCT is feasible and could be considered for younger patients in the upfront setting.

[Preventative and therapeutic relapse strategies after allogeneic hematopoietic stem cell transplantation: Guidelines from the Francophone society of bone marrow transplantation and cellular therapy (SFGM-TC)]

Disease relapse remains the first cause of mortality of hematological malignancies after allogeneic hematopoietic stem cell transplantation (allo-HCT). The risk of recurrence is elevated in patients with high-risk cytogenetic or molecular abnormalities, as well as when allo-HCT is performed in patients with refractory disease or with persistent molecular or radiological (PET-CT scan) residual disease. Within the frame of the 7th annual workshops of the francophone society for bone marrow transplantation and cellular therapy, the working group reviewed the literature in order to elaborate unified guidelines for the prevention and treatment of relapse after allo-HCT. For high risk AML and MDS, a post transplant maintenance strategy is possible, using hypomethylating agents or TKI anti-FLT3 when the target is present. For Philadelphia positive ALL, there was a consensus for the use of post-transplant TKI maintenance. For lymphomas, there are no strong data on the use of post-transplant maintenance, and hence a preemptive strategy is recommended based on modulation of immunosuppression, close follow-up of donor chimerism, and donor lymphocytes infusion. For multiple myeloma, even though the indication of allo-HCT is controversial, our recommendation is post transplant maintenance using bortezomib, due to its a good toxicity profile without increasing the risk of GVHD.

Tandem autologous/allogeneic hematopoietic cell transplantation with bortezomib maintenance therapy for high-risk myeloma

We evaluated tandem autologous/allogeneic hematopoietic cell transplantation followed by bortezomib maintenance therapy in a prospective phase 2 trial of treatment of high-risk multiple myeloma. The high-dose conditioning regimen for autologous hematopoietic cell transplantation consisted of melphalan 200 mg/m². The nonmyeloablative conditioning regimen for the allogeneic transplant involved low-dose total body irradiation (2 Gy) with or without fludarabine (30 mg/m² × 3 days). Among the 31 patients enrolled, 26 (84%) proceeded to HLA-matched allogeneic hematopoietic cell transplantation at a median of 61 (range, 41-168) days following the autologous transplant. Twenty-one patients (68%) started bortezomib (1.6 mg/m² IV or 2.6 mg/m² subcutaneously every 14 days for 9 months) at a median of 79 (range, 63-103) days after allogeneic transplantation. With a median follow-up of 51 (range, 16-86) months and based on intention to treat, the 2-year and 4-year progression-free survival and overall survival estimates among 24 newly diagnosed high-risk patients were 71% and 75%, and 52% and 61%, respectively. The 7 patients enrolled with relapsed or persistent disease had a 2-year and 4-year progression-free survival and overall survival rates of 14% and 43%, and 14% and 29%, respectively. These findings suggest that for patients with newly diagnosed high-risk multiple myeloma, bortezomib maintenance therapy after tandem autologous/allogeneic hematopoietic cell transplantation is safe and may prevent disease progression until full establishment of a graft-versus-myeloma effect. This benefit, however, does not extend to patients who enroll after unsuccessful prior therapy. This trial was registered at www.clinicaltrials.gov as #NCT00793572.

Allogeneic Hematopoietic Cell Transplantation for Myeloma: When and in Whom Does It Work

The growing list of available therapies for patients with multiple myeloma has resulted in tremendously high response rates and prolonged survival. However, the cure remains elusive. A continued effort at developing strategies to utilize all available treatment modalities in the most effective manner is needed. Allogeneic hematopoietic cell transplantation (allo-HCT) is a robust platform, associated with high response rates, and provides a unique foundation on which immune therapies and novel agents can be employed to improve clinical outcomes. Patients with high-risk myeloma and those relapsing after novel agent-based therapies or early after an autologous HCT should be considered for allo-HCT, ideally in a clinical trial setting. Results from several ongoing studies are expected to provide important information that will help determine the place of allo-HCT in the myeloma treatment algorithm.

Outcomes of unrelated cord blood transplantation in patients with multiple myeloma: a survey on behalf of Eurocord, the Cord Blood Committee of Cellular Therapy and Immunobiology Working Party, and the Chronic Leukemia Working Party of the EBMT

Although allogeneic stem cell transplantation is not a standard therapy for multiple myeloma, some patients can benefit from this intense therapy. There are few reports on outcomes after umbilical cord blood transplantation in multiple myeloma, and investigation of this procedure is warranted. We retrospectively analyzed 95 patients, 85 with multiple myeloma and 10 with plasma cell leukemia, receiving single or double umbilical cord blood transplantation from 2001 to 2013. Median follow up was 41 months. The majority of patients received a reduced intensity conditioning. The cumulative incidence of neutrophil engraftment was 97%±3% at 60 days, and that of 100-day acute graft-versus-host disease grade II-IV was 41%±5%. Chronic graft-versus-host disease at two years was 22%±4%. Relapse and non-relapse mortality was 47%±5% and 29%±5% at three years, respectively. Three-year progression-free survival and overall survival were 24%±5% and 40%±5%, respectively. Anti-thymocyte globulin was associated with decreased incidence of acute graft-versus-host disease, higher non-relapse mortality, decreased overall and progression-free survival. Patients with high cytogenetic risk had higher relapse, and worse overall and progression-free survival. In conclusion, umbilical cord blood transplantation is feasible for multiple myeloma patients.

Bortezomib for the prevention and treatment of graft-versus-host disease after allogeneic hematopoietic stem cell transplantation

Allogeneic hematopoietic stem cell transplantation is the standard treatment for a variety of benign and malignant conditions. However, graft-versus-host disease (GvHD) continues to present a major barrier to the success and wide applicability of this procedure. Although current GvHD prevention and treatment regimens exclusively target T cells, bortezomib, a reversible proteasome inhibitor, possesses unique immune regulatory activities that span a wide variety of cellular processes of T and dendritic cells essential for the development of GvHD. Herein, we review the current understanding of the effects of bortezomib in vitro and in animal models and summarize the clinical data relevant to its use in the prevention and treatment of GvHD. We conclude with an outline of the remaining challenges and opportunities to optimize bortezomib's potential role in this setting.

Evolving paradigms in the treatment of relapsed/refractory multiple myeloma: increased options and increased complexity

The use of modern therapies such as thalidomide, bortezomib and lenalidomide coupled with upfront high-dose therapy and autologous stem cell transplant (ASCT) has resulted in improved survival in patients with newly diagnosed multiple myeloma (MM). However, patients with relapsed/refractory multiple myeloma (RRMM) often have poorer clinical outcomes and might benefit from novel therapeutic strategies. Emerging therapies, such as deacetylase inhibitors, monoclonal antibodies and new proteasome inhibitors, appear promising and may change the therapeutic landscape in RRMM. A limited number of studies has shown a benefit with salvage ASCT in patients with RRMM, although there remains ongoing debate about its timing and effectiveness. Improvement in transplant outcomes has re-ignited a debate on the timing and possible role for salvage ASCT and allogeneic stem cell transplant in RRMM. As the treatment options for management of patients with RRMM become increasingly complex, physicians must consider both disease- and patient-related factors in choosing the appropriate therapeutic approach, with the goal of improving efficacy while minimizing toxicity.

A phase II study of bortezomib plus prednisone for initial therapy of chronic graft-versus-host disease

Chronic graft-versus-host disease (GVHD) induces significant morbidity and mortality after allogeneic hematopoietic stem cell transplantation. Corticosteroids are standard initial therapy, despite limited efficacy and long-term toxicity. Based on our experience using bortezomib as effective acute GVHD prophylaxis, we hypothesized that proteasome-inhibition would complement the immunomodulatory effects of corticosteroids to improve outcomes in chronic GVHD (cGVHD). We undertook a single-arm phase II trial of bortezomib plus prednisone for initial therapy of cGVHD. Bortezomib was administered at 1.3 mg/m(2) i.v. on days 1, 8, 15, and 22 of each 35-day cycle for 3 cycles (15 weeks). Prednisone was dosed at .5 to 1 mg/kg/day, with a suggested taper after cycle 1. All 22 enrolled participants were evaluable for toxicity; 20 were evaluable for response. Bortezomib plus prednisone therapy was well tolerated, with 1 occurrence of grade 3 sensory peripheral neuropathy possibly related to bortezomib. The overall response rate at week 15 in evaluable participants was 80%, including 2 (10%) complete and 14 (70%) partial responses. The organ-specific complete response rate was 73% for skin, 53% for liver, 75% for gastrointestinal tract, and 33% for joint, muscle, or fascia involvement. The median prednisone dose decreased from 50 mg/day to 20 mg/day at week 15 (P < .001). The combination of bortezomib and prednisone for initial treatment of cGVHD is feasible and well tolerated. We observed a high response rate to combined bortezomib and prednisone therapy; however, in this single-arm study, we could not directly measure the impact of bortezomib. Proteasome inhibition may offer benefit in the treatment of cGVHD and should be further evaluated.

Current and emerging strategies for the prevention of graft-versus-host disease

Graft-versus-host disease (GVHD) represents the most serious and challenging complication of allogeneic haematopoietic stem-cell transplantation (HSCT). New insights on the role of regulatory T-cells, T cells, and antigen-presenting cells have led to an improved understanding of the pathophysiology of GVHD. However, little progress has been made since the introduction of calcineurin-inhibitor-based regimens in the mid-1980s. Despite standard prophylaxis with these regimens, GVHD still develops in approximately 40-60% of recipients. Thus, there is a need for developing newer approaches to mitigate GVHD, which may facilitate the use of allogeneic HSCT for the treatment of a wider range of haematological cancers. We discuss the rationale, clinical evidence, and outcomes of current (and widely employed) strategies for GVHD prophylaxis, namely calcineurin-inhibitor-based regimens (such as cyclosporine or tacrolimus) combined with methotrexate or mycophenolate mofetil. We assess the clinical evidence for emerging approaches in the prevention of GVHD, including therapies targeting T cells or B cells, the use of mesenchymal stem cells, chemo-cytokine antagonists (such as maraviroc, TNF-α inhibitor, IL-2 receptor antagonist, IL-6 inhibitor), and the use of novel molecular regulators that target multiple cell types simultaneously, including atorvastatin, bortezomib, and epigenetic modulators.

Proteasome inhibitors as immunosuppressants: biological rationale and clinical experience

Accumulating evidence supports the potential of proteasome inhibitors as immunosuppressants. Proteasome inhibitors interfere with antigen processing and presentation, as well as with the signaling cascades involved in immune cell function and survival. Both myeloma and healthy plasma cells appear to be highly susceptible to proteasome inhibitors due to impaired proteasomal activity in both cell types. As a consequence, these agents can be used to reduce antibody production and thus prevent antibody-induced tissue damage. Several clinical studies have explored the potential of bortezomib, a peptide boronate proteasome inhibitor, for treating immune disorders, such as antibody-mediated organ rejection and graft-versus-host disease (GVHD), with encouraging results. Here, we discuss the biological rationale for the use of proteasome inhibitors as immunosuppressive agents and review the clinical experience with bortezomib in immune-mediated diseases.

Targeting the proteasome with bortezomib in multiple myeloma: update on therapeutic benefit as an upfront single agent, induction regimen for stem-cell transplantation and as maintenance therapy

Bortezomib is the first therapeutic inhibitor of the proteasome that has demonstrated a significant clinical response in patients with otherwise refractory or rapidly advancing disease. Bortezomib has received US Federal Drug Administration approval for the treatment of the hematologic malignancies such as multiple myeloma and mantle cell lymphoma. Herein, the use of bortezomib as an upfront therapy, as an induction regimen before stem-cell transplantation and as maintenance therapy in the treatment of multiple myeloma is discussed.

Emerging therapies in hematopoietic stem cell transplantation

Despite improvements to hematopoietic stem cell transplantation over the past several decades, further advances are necessary to achieve: improved control of toxicities like graft-versus-host disease; enhanced immunologic reconstitution posttransplantation; and reduction in relapse risk via enhancement of graft-versus-tumor responses. Achieving these disparate hematopoietic stem cell transplantation goals will likely require the introduction of novel therapeutic agents to the current armamentarium. In this article, we outline preclinical and early-phase clinical data indicating the potential of proteasome-inhibitor therapy (bortezomib), hypomethylating agent therapy (azacytidine), and histone deacetylase-inhibitor therapy (vorinostat) to help improve hematopoietic stem cell transplantation outcomes.

Lenalidomide plus donor-lymphocytes infusion after allogeneic stem-cell transplantation with reduced-intensity conditioning in patients with high-risk multiple myeloma

Myeloma relapse is the main cause of death after allogeneic stem cell transplantation. The aim of our observational study was to evaluate the anti-myeloma effect of lenalidomide followed by donor-lymphocyte infusion (DLI) as post-transplantation adoptive immunotherapy. Twelve patients with refractory myeloma were analyzed. The median age at transplantation was 56 years (range, 46-64 years). All patients received reduced-intensity conditioning. Patients were included if progressive or residual disease was observed at day +100 and if no signs of graft-vs-host disease were evident. DLIs were administered after two cycles of lenalidomide. Median dose of lenalidomide was 15 mg (range, 10-25 mg). Patients received a median of six cycles (range, 1-10 cycles). Nine patients (60%) received an escalating dose of DLI. The 1 and 2-year probability of progression-free survival was 75% and 50%, and overall survival was 83% and 69%, respectively. Median overall survival was not reached and median progression-free survival was 23 months. Lenalidomide is well tolerated after allogeneic stem cell transplantation; the combination with DLI did not cause a higher risk of graft-vs-host disease; an immunological synergistic effect was probably present with this strategy. This combination should be evaluated further in a larger cohort of patients.

Efficacy of continuous, daily, oral, ultra-low-dose 200 mg acyclovir to prevent herpes zoster events among bortezomib-treated patients: a report from retrospective study

OBJECTIVE

Herpes zoster is the most common infection in patients treated with bortezomib-containing regimens for multiple myeloma. Some clinical trials have reported on the use of acyclovir prophylaxis to decrease the incidence of herpes zoster. However, the appropriate acyclovir dose and duration of prophylaxis remain unclear. The primary objective of this study was to evaluate the efficacy of continuous oral 200 mg/day acyclovir prophylaxis and the secondary objective was to determine the risk factors for developing herpes zoster.

METHODS

We collected medical information from consecutive patients who received bortezomib with or without acyclovir prophylaxis for relapsed or refractory multiple myeloma at our hospital and retrospectively analyzed the efficacy of acyclovir prophylaxis and the parameters for predicting the risk factors for developing herpes zoster. The definition of acyclovir prophylaxis was oral continuous administration of 200 mg of once daily, without cessation, during the entire period of bortezomib treatment.

RESULTS

Six of the 33 patients in the study developed herpes zoster during bortezomib treatment. No varicella-zoster virus reactivation was observed in the 19 patients in the acyclovir prophylaxis group. The incidence of herpes zoster was significantly higher in the group that did not receive acyclovir prophylaxis (43%, 6 of 14 patients) than in the group that did (0%, 0 of 19; P = 0.003). The predictive factors for varicella-zoster virus reactivation were male sex (P = 0.035) and the use of acyclovir (P = 0.003).

CONCLUSIONS

Continuous prophylaxis by oral 200 mg/day acyclovir in multiple myeloma patients receiving bortezomib treatment is effective and sufficient in preventing herpes zoster.

Reduced-intensity allogeneic hematopoietic stem cell transplantation for multiple myeloma: a concise review

Reduced-intensity conditioning (RIC) allogeneic hematopoietic stem cell transplantation (HSCT) can result in reliable donor engraftment, relatively low treatment-related mortality, and sustained remissions in the treatment of multiple myeloma. However, substantial cytoreduction pre-allografting is often necessary because of a variable graft-versus-myeloma effect. The use of RIC allogeneic HSCT immediately after autologous HSCT provides a temporal separation between tumor reduction by high-dose chemotherapy and the graft-versus-myeloma effect. There are currently a number of prospective trials attempting to address the issue of whether this strategy leads to decreases in relapse and/or improvement in overall survival as compared with double autologous transplants. Unfortunately, similar to autografting, relapse remains the major cause of treatment failure after RIC allogeneic HSCT. To improve treatment results with allografting, consideration should be given to incorporating immunomodulatory drugs and targeted treatments to enhance pretransplantation remission status, as posttransplantation maintenance therapy, or in combination with donor lymphocyte infusions for refractory or relapsed disease. Studies exploring these strategies are ongoing.

Approaches to relapse after allogeneic stem cell transplantation

PURPOSE OF REVIEW

Relapse has become the leading cause of death following allogeneic hematopoietic stem cell transplantation (HSCT). Despite improved understanding of the biology that underlies the graft-versus-leukemia/tumor effect the relapse rate did not decrease over the past 20 years. In general, prognosis is poor for patients who relapsed to an allograft since effective treatment options are limited. Here, we review the available and upcoming treatment approaches for relapse.

RECENT FINDINGS

Treatment of relapse after allogeneic HSCT has been rarely investigated systematically and results differ substantially from diseases. Withdrawal of immunosuppressive medication, donor lymphocyte infusions with or without chemotherapy and/or second allogeneic HSCT are the most used options. New specific cellular approaches such as disease-specific T-cells, alloreactive natural killer cells or vaccination strategies are under investigation. Novel agents such as tyrosine-kinase inhibitors, hypomethylating agents, monoclonal antibodies, immunomodulating drugs, or proteasome-inhibitors either alone or in combination with adoptive immunotherapy are upcoming promising options, but valid data are lacking so far.

SUMMARY

With some exceptions (chronic myeloid leukemia), treatment options for patients who relapse are limited. The results are poor and the majority of patients ultimately die of their disease. More effort and research is needed to prevent and treat relapse after allogeneic HSCT.

Unrelated stem cell transplantation for patients with multiple myeloma

PURPOSE OF REVIEW

The role of allogeneic stem cell transplantation (SCT) in treatment of myeloma patients is still controversial. Meanwhile, the numbers of unrelated SCT for hematological diseases in Europe are higher than for human leukocyte antigen (HLA)-identical sibling transplantations, but in multiple myeloma only 39% of the allogeneic transplantations are performed from unrelated donors and only a minority were done within prospective clinical trials.

RECENT FINDINGS

The few published data of unrelated SCT in multiple myeloma reported a higher treatment-related mortality for standard myeloablative conditioning in comparison to reduced-intensity conditioning. Despite the heterogeneous patient selection in the trial, lower nonrelapse mortality and improved survival can be achieved by careful donor selection (10/10 HLA-alleles, male donor). Natural killer-alloreactivity might play a role, but conclusive data are lacking. Transplantation in more advanced or refractory patients is associated with an inferior outcome. The results of an unrelated SCT seem to be comparable to those of HLA-identical siblings, but a direct comparison is lacking so far.

SUMMARY

Unrelated SCT in multiple myeloma is feasible, but prospective clinical trials using unrelated stem cell donors are urgently needed to define the role of an unrelated SCT in multiple myeloma in the era of novel agents.

Novel agents to improve outcome of allogeneic transplantation for patients with multiple myeloma

Over the last few decades therapy for multiple myeloma has improved remarkably. In particular, the introduction of novel agents has allowed improved response rates prior to, and after, stem cell transplantation with extension of progression-free survival in high-risk patients. Nevertheless, most patients relapse, leaving multiple myeloma an incurable disease. Despite being the only treatment option that has real curative potential, allogeneic transplantation has not shown its superiority to autologous transplantation due to its high morbidity and mortality rates. This review highlights how novel agents might help to reduce treatment-related mortality and to improve tumor control prior to and post-allogeneic stem cell transplant, which will hopefully result in significantly improved long-term disease control, and maybe a cure following this treatment modality.

NCI First International Workshop on the Biology, Prevention, and Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation: Report from the Committee on Treatment of Relapse after Allogeneic Hematopoietic Stem Cell Transplantation

Relapse is a major cause of treatment failure after allogeneic hematopoietic stem cell transplantation (alloHSCT). Treatment options for relapse have been inadequate, and the majority of patients ultimately die of their disease. There is no standard approach to treating relapse after alloHSCT. Withdrawal of immune suppression and donor lymphocyte infusions are commonly used for all diseases; although these interventions are remarkably effective for relapsed chronic myelogenous leukemia, they have limited efficacy in other hematologic malignancies. Conventional and novel chemotherapy, monoclonal antibody therapy, targeted therapies, and second transplants have been utilized in a variety of relapsed diseases, but reports on these therapies are generally anecdotal and retrospective. As such, there is an immediate need for well-designed, disease-specific trials for treatment of relapse after alloHSCT. This report summarizes current treatment options under investigation for relapse after alloHSCT in a disease-specific manner. In addition, recommendations are provided for specific areas of research necessary in the treatment of relapse after alloHSCT.

International Myeloma Working Group Consensus Statement Regarding the Current Status of Allogeneic Stem-Cell Transplantation for Multiple Myeloma

Purpose

To define consensus statement regarding allogeneic stem-cell transplantation (Allo-SCT) as a treatment option for multiple myeloma (MM) on behalf of International Myeloma Working Group.

Patients and Methods

In this review, results from prospective and retrospective studies of Allo-SCT in MM are summarized.

Results

Although the introduction of reduced-intensity conditioning (RIC) has lowered the high treatment-related mortality associated with myeloablative conditioning, convincing evidence is lacking that Allo-RIC improves the survival compared with autologous stem-cell transplantation.

Conclusion

New strategies are necessary to make Allo-SCT safer and more effective for patients with MM. Until this is achieved, Allo-RIC in myeloma should only be recommended in the context of clinical trials.

Role of allogeneic transplantation in multiple myeloma in the era of new drugs

High-dose melphalan with autologous stem cell rescue has been regarded as the standard of care for patients with newly diagnosed myeloma up to the age of 65–70 years. The recent development of agents with potent anti-tumor activity such as thalidomide, lenalidomide and bortezomib has further improved overall survival and response rates. However, relapse is a continuous risk.

Allografting is a potentially curative treatment for a subset of multiple myeloma patients for its well documented graft-vs-myeloma effects. However, its role has been hotly debated. Even though molecular remissions have been reported up to 50% after high-dose myeloablative conditionings, their applications, given the high toxicity, have been for long limited to younger relapsed/refractory patients. These limitations have greatly been reduced through the introduction of non-myeloablative/reduced-intensity conditionings.

The introduction of new drugs, characterised by low risks of early mortality, indeed requires to define role and timing of an allograft to capture the subset of patients who may most benefit from graft-vs-myeloma effects.

Ultimately, new drugs should not be viewed as mutually exclusive with an allograft. They may be employed to achieve profound cytoreduction before and enhance graft-versus-myeloma effects as consolidation/maintenance therapy after an allograft. However, this combination should be explored only in well-designed clinical trials.

Hematopoietic stem cell transplantation for multiple myeloma beyond 2010

Autologous stem cell transplantation (ASCT) is considered the gold standard in the frontline therapy of younger patients with multiple myeloma because it results in higher complete remission (CR) rates and longer event-free survival than conventional chemotherapy. The greatest benefit from ASCT is obtained in patients achieving CR after transplantation, the likelihood of CR being associated with the M-protein size at the time of transplantation. The incorporation of novel agents results in higher pre- and posttransplantation CR rates. Induction with bortezomib-containing regimens is encouraging in patients with poor-risk cytogenetics. However, longer follow-up is required to assess the impact of this increased CR on long-term survival. The results of posttransplantation consolidation/maintenance with new drugs are encouraging. All this indicates that, in the era of novel agents, high-dose therapy should be optimized rather than replaced. Because of its high transplantation-related mortality, myeloablative allografting has been generally replaced by reduced-intensity conditioning (reduced intensity conditioning allogeneic transplantation). The best results are achieved after a debulky ASCT, with a progression-free survival plateau of 25% to 30% beyond 6 years from reduced intensity conditioning allogeneic transplantation. The development of novel reduced-intensity preparative regimens and peri- and posttransplantation strategies aimed at minimizing graft-versus-host disease, and enhancing the graft-versus-myeloma effect are key issues.

Proteasome inhibition and allogeneic hematopoietic stem cell transplantation: a review

The proteasome and its associated ubiquitin protein modification system have proved to be an important therapeutic target in the treatment of multiple myeloma and other cancers. In addition to direct antitumor effects, proteasome inhibition also exerts strong effects on nonneoplastic immune cells. This indicates that proteasome inhibition, through the use of agents like bortezomib, could be used therapeutically to modulate immune responses. In this review we explore the emerging data, both preclinical and clinical, highlighting the importance of proteasome targeting of immunologic responses, primarily in the context of allogeneic hematopoietic stem cell transplantation (HSCT), both for the control of transplant-related toxicities like acute and chronic graft-versus-host disease (aGVHD, cGHVHD), and for improved malignant disease control after allogeneic HSCT.

Proteasome inhibitors in the treatment of multiple myeloma

Targeting intracellular protein turnover by inhibiting the ubiquitin-proteasome pathway as a strategy for cancer therapy is a new addition to our chemotherapeutic armamentarium, and has seen its greatest successes against multiple myeloma. The first-in-class proteasome inhibitor, bortezomib, was initially approved for treatment of patients in the relapsed/refractory setting as a single agent, and was recently shown to induce even greater benefits as part of rationally designed combinations that overcome chemoresistance. Modulation of proteasome function is also a rational approach to achieve chemosensitization to other antimyeloma agents, and bortezomib has now been incorporated into the front-line setting. Bortezomib-based induction regimens are able to achieve higher overall response rates and response qualities than was the case with prior standards of care, and unlike these older approaches, maintain efficacy in patients with clinically and molecularly defined high-risk disease. Second-generation proteasome inhibitors with novel properties, such as NPI-0052 and carfilzomib, are entering the clinical arena, and showing evidence of antimyeloma activity. In this spotlight review, we provide an overview of the current state of the art use of bortezomib and other proteasome inhibitors against multiple myeloma, and highlight areas for future study that will further optimize our ability to benefit patients with this disease.

Role of allogeneic stem cell transplantation in multiple myeloma

High-dose chemotherapy with autologous stem cell rescue has been regarded as the standard of care for young newly diagnosed myeloma patients. Moreover, the development of new agents with potent anti-tumor activity has further improved survival. However, relapse is a continuous risk primarily due to the inability of current therapies to eradicate all myeloma cells. Allografting is the only potentially curative treatment at least for a subset of multiple myeloma patients due to its well documented graft-versus-myeloma effects. Given the high transplant mortality of the high-dose myeloablative conditionings used until recently, allografting has for a long time been limited to younger relapsed/refractory patients. These limitations have been reduced significantly by the use of reduced-intensity conditionings. Although results of recent trials are encouraging, the subset of patients who may benefit most from an allograft remains to be determined. An overview of the clinical outcomes obtained with allografting and possible future developments are reported.

Post-transplant immunotherapy with donor-lymphocyte infusion and novel agents to upgrade partial into complete and molecular remission in allografted patients with multiple myeloma

OBJECTIVE

To investigate post-transplant immunotherapy with escalating donor-lymphocyte infusions (DLI) and novel agents (thalidomide, bortezomib, and lenalidomide) to target complete remission (CR).

MATERIALS AND METHODS

Thirty-two patients with multiple myeloma who achieved only partial remission after allogeneic stem cell transplantation were treated with DLI. If no CR was achieved, one of the novel agents was added to target CR.

RESULTS

CR defined either by European Group for Blood and Marrow Transplantation criteria, flow cytometry, or molecular methods as assessed by patient-specific immunoglobulin H-polymerase chain reaction or plasma cell chimerism polymerase chain reaction was accomplished in 59%, 63%, and 50% of patients, respectively. Achievement of CR resulted in improved 5-year progressive-free and overall survival, according to European Group for Blood and Marrow Transplantation criteria (53% vs 35%; p=0.03 and 90% vs 62%; p=0.06), flow cytometry (74% vs 15%; p=0.001 and 100% vs 52%; p=0.1), or molecular methods (84% vs 38%; p=0.001 and 100% vs 71%; p=0.03).

CONCLUSIONS

Our finding demonstrates the clinical relevance of posttransplantation therapies to upgrade remission, and of remission's depth for long-term survival in myeloma patients.

A Phase II trial of autologous stem cell transplantation followed by mini-allogeneic stem cell transplantation for the treatment of multiple myeloma: an analysis of Eastern Cooperative Oncology Group ECOG E4A98 and E1A97

Conventional allogeneic hematopoietic stem cell transplantation (HSCT) for multiple myeloma is associated with high transplantation-related mortality (TRM). Nonmyeloablative allogeneic transplantation (NST) uses the well-known graft-versus-myeloma (GVM) effect to eradicate minimal residual disease. The Eastern Cooperative Oncology Group conducted a Phase II trial of autologous HSCT followed by NST to provide maximal tumor cytoreduction to allow for a subsequent GVM effect. Patients received melphalan 200 mg/m(2) with autologous HSCT, followed by fludarabine 30 mg/m(2) in 5 daily doses and cyclophosphamide 1 g/m(2) in 2 daily doses with matched sibling donor NST. Graft-versus-host disease (GVHD) prophylaxis included cyclosporine and corticosteroids. The primary endpoints were TRM, graft failure, acute GVHD, progression-free survival (PFS), and overall survival (OS). Thirty-two patients were enrolled into the study; 23 patients completed both transplantations (72%). Best responses post-NST were 7 (30%) complete remission (CR), 11 (48%) partial remission (PR), 2 (9%) no response, and 3 (13%) not evaluable. Acute grade III-IV GVHD was observed in 4 patients (17%), and chronic GVHD was seen in 13 patients (57%; 7 limited, 6 extensive). Chronic GVHD resulted in the following responses: 3 (23%) CR, 1 continuing CR, and 6 (46%) PR. Two patients (8.7%) had early TRM. With a median follow up of 4.6 years, the median PFS was 3.6 years, and the 2-year OS was 78%. Our findings indicate that autologous HSCT followed by NST is feasible, with a low early TRM in a cooperative group setting. The overall response rate was 78%, including 30% CR, similar to other reports for autologous HSCT-NST. Because a plateau in PFS or OS was not observed with this treatment approach even in patients achieving CR, we suggest that future studies use posttransplantation maintenance therapy.

Nonmyeloablative allografting for newly diagnosed multiple myeloma: the experience of the Gruppo Italiano Trapianti di Midollo

Despite recent advances, allografting remains the only potential cure for myeloma. From July 1999 to June 2005, 100 newly diagnosed patients younger than 65 years were enrolled in a prospective multicenter study. First-line treatment included vincristin, adriamycin, and dexamethasone (VAD)-based induction chemotherapy, a cytoreductive autograft (melphalan 200 mg/m(2)) followed by a single dose of nonmyeloablative total body irradiation and allografting from an human leukocyte antigen (HLA)-identical sibling. Primary end points were the overall survival (OS) and event-free survival (EFS) from diagnosis. After a median follow-up of 5 years, OS was not reached, and EFS was 37 months. Incidences of acute and chronic graft-versus-host disease (GVHD) were 38% and 50%, respectively. Complete remission (CR) was achieved in 53% of patients. Profound cytoreduction (CR or very good partial remission) before allografting was associated with achievement of posttransplantation CR (hazard ratio [HR] 2.20, P = .03) and longer EFS (HR 0.33, P < .01). Conversely, development of chronic GVHD was not correlated with CR or response duration. This tandem transplantation approach allows prolonged survival and long-term disease control in patients with reduced tumor burden at the time of allografting. We are currently investigating the role of "new drugs" in intensifying pretransplantation cytoreduction and posttransplantation graft-versus-myeloma effects to further improve clinical outcomes. (http://ClinicalTrials.gov; NCT-00702247.).

Long-term outcome of patients with multiple myeloma after autologous hematopoietic cell transplantation and nonmyeloablative allografting

Autologous hematopoietic cell transplantation (HCT) followed by nonmyeloablative allogeneic HCT (auto/alloHCT) provides cytoreduction and graft-versus-myeloma effects. We report on long-term outcomes of 102 patients with multiple myeloma who received auto/alloHCT with a median follow-up of 6.3 years. Treatment consisted of high-dose melphalan and autograft followed by 2-Gy total body irradiation, with or without fludarabine, and alloHCT from human leukocyte antigen-identical siblings. Postgrafting immunosuppressive agent was cyclosporine or tacrolimus and mycophenolate mofetil. Forty-two percent of patients developed grade 2 to 4 acute graft-versus-host disease (GVHD) and 74% extensive chronic GVHD. Five-year nonrelapse mortality after allografting was 18%, 95% related to GVHD or infections. Among 95 patients with detectable disease, 59 achieved complete remissions. Median time to progression was 5 years. Median overall survival (OS) was not reached. Median progression-free survival (PFS) was 3 years. Five-year OS and PFS were 64% and 36%, respectively. Seventy-three patients receiving autoHCT within 10 months from treatment initiation had 5-year OS of 69% and PFS of 37%. In multivariate analysis, beta-2-microglobulin of more than 3.5 microg/mL at diagnosis and auto/alloHCT more than 10 months after treatment initiation correlated with shorter OS (P = .03 and P = .02) and PFS (P = .04 and P = .03), whereas Karnofsky scores less than 90% at allotransplantation correlated with shorter PFS only (P = .005). Long-term disease control and GVHD remain key issues.

Analysis of herpes zoster events among bortezomib-treated patients in the phase III APEX study

PURPOSE

The aim of this subset analysis was to determine if bortezomib treatment is associated with increased incidence of varicella-zoster virus (VZV) reactivation in patients with relapsed multiple myeloma (MM).

PATIENTS AND METHODS

Incidence of herpes zoster was evaluated in 663 patients with relapsed MM from the phase III APEX trial comparing single-agent bortezomib with high-dose dexamethasone.

RESULTS

Bortezomib was associated with a significantly higher incidence of herpes zoster compared with dexamethasone treatment (13%, 42 of 331 v 5%, 15 of 332; P = .0002). Most herpes zoster infections were grade 1/2; incidences of grade 3/4 events (1.8% v 1.5%) and infections considered serious adverse events (1.5% v 0.9%) were similar between treatment arms, and no herpes zoster-related deaths occurred. Neither the time to onset of the herpes event nor the patients' absolute lymphocyte counts at baseline differed significantly between arms. VZV reactivation was the only herpes viral event noted to be significantly elevated in the bortezomib treatment group compared with the dexamethasone treatment group (P = .0002). The incidence of non-VZV-related herpes viral infections was comparable between arms. No additional risk factors for herpes zoster reactivation were identified.

CONCLUSION

Further studies are needed to explain these observations and their implications; however, for patients treated with bortezomib or bortezomib-containing regimens, the risk of VZV reactivation should be monitored and routine use of antiviral prophylaxis considered.

Role of stem cell transplantation

Hematopoietic stem cell transplantation (SCT) was introduced in the treatment of multiple myeloma in the 1980s. In the autologous setting, the use of peripheral blood stem cells instead of bone marrow has markedly improved feasibility. In fit patients who have normal renal function and are younger than 65 years of age, randomized studies have shown the superiority of autologous stem cell transplantation (ASCT) compared with conventional chemotherapy. ASCT is now considered the standard of care in this population of patients. It is currently challenged, however, by the introduction of novel agents, such as thalidomide, bortezomib, and lenalidomide. The role of allogenic SCT remains controversial, even with reduced intensity conditionings. Prospective studies still are needed to evaluate the impact of both autologous and allogeneic SCT in this new era.

Stem-Cell Transplantation for Multiple Myeloma in the Era of Novel Drugs

The treatment of multiple myeloma (MM) is changing rapidly. During the last 10 years, higher rates of complete response (CR) and prolonged progression-free and overall survival have been seen with high-dose chemotherapy plus autologous stem-cell transplantation (HDT-ASCT). Achievement of CR and good partial response have been shown to be key prognostic factors for prolonged survival, with eradication of minimal residual disease seeming crucial to long-term disease-free survival. Until recently, high rates of CR and other major responses were primarily seen with HDT-ASCT, but insights into the biology of MM have led to the development and approval of new drugs with significant activity, and new induction regimens based on these novel agents are offering improved responses. Thalidomide, bortezomib, and lenalidomide have been combined with corticosteroids, alkylators, and anthracyclines in front-line MM treatment. Phase II studies have indicated that high rates of response and CR may be achieved. The substantial activity seen with these new drug combinations has prompted a re-examination of the role of SCT in MM treatment. Will achievement of major responses with these new regimens translate into improved survival after consolidation with transplantation? Will these improved induction regimens reduce the need for tandem transplantation, or does achievement of CR obviate the need for front-line transplantation altogether? To help address these questions, randomized trials are needed, as well as tests with improved sensitivity to better define depth of remission.

Reduced intensity conditioning with thiotepa, fludarabine, and melphalan is effective in advanced multiple myeloma

Fifty-three patients with multiple myeloma (MM) underwent an allogeneic stem cell transplant (HSCT) from their HLA identical siblings using a reduced-intensity conditioning consisting of thioteopa 5 mg/kg, fludarabine 90 mg/m(2), and melphalan 80 mg/m(2). Their median age was 52 years (range 38 - 68) and the interval from diagnosis 12 months. Forty-three patients (82%) had advanced disease and 33 had previously been treated with high-dose therapy with one (N = 21), or more (N = 12) autologus transplants. Ten (18%) had their allograft programmed after induction chemotherapy. The majority (N = 44) received peripheral blood as stem cell source. Acute graft-versus-host disease (GVHD) grade II - IV developed in 45%, but grade III - IV in only 5%. Cumulative incidence of chronic GVHD was 64%. Sixty-two per cent were in complete remission (CR) following transplantation. Transplant-related mortality was 13%. Relapse incidence was 32%. With a median follow-up of 22 months, 3-year overall survival is 45% and progression free survival (PFS) 37%. The thiotepa, fludarabine, and melphalan conditioning regimen can produce remissions in the majority of MM patients with a limited transplant mortality rate. When used as first line treatment the results of transplantation appear even more encouraging.

Targeted treatments to improve stem cell outcome: old and new drugs

Thalidomide, lenalidomide and bortezomib have been approved for the treatment of relapsed or refractory multiple myeloma in the recent years. These agents are now being increasingly integrated into therapeutic regimens for newly diagnosed patients. First data are available on the promising activity of these novel agents in induction therapy, as well as maintenance treatment to improve outcome after stem cell transplantation. Whether these early results will lead to prolonged overall survival and thereby ultimately redefine the role of stem cell transplantation in first-line treatment of multiple myeloma will be one of the most important questions to be answered in the coming years. Bone Marrow Transplantation (2007) 40, 1129-1137; doi:10.1038/sj.bmt.1705829; published online 3 September 2007.

The allogeneic dilemma

The place of allogeneic SCT in the management of multiple myeloma remains controversial. Although it may induce long-term clinical and molecular remissions, the very high transplant-related toxicity after a myeloablative preparative regimen has limited its role to younger patients as first-line treatment option. Even with this limited indication, toxic death rate related to infections and GVHD is considered too high and this strategy has been almost abandoned. Reduced intensity conditioning (RIC) regimens look promising, as the transplant-related mortality is low even with matched unrelated donors and can be considered for older patients up to the age of 65 years. However when used in patients with a high tumor burden or with chemo-resistant disease, the immunologic effect of the graft is not sufficient to avoid relapses. Therefore, RIC allotransplantation is currently used after tumor mass reduction with high-dose therapy followed by autologous SCT. A recently published Italian study shows that this strategy induces better event-free survival than double autologous SCT due to a reduced relapse rate. The questions raised by this encouraging result are discussed in this paper.