Improved Outcomes After Autologous Hematopoietic Cell Transplantation for Light Chain Amyloidosis: A Center for International Blood and Marrow Transplant Research Study

PURPOSE

Autologous hematopoietic cell transplantation, or autotransplantation, is effective in light-chain amyloidosis (AL), but it is associated with a high risk of early mortality (EM). In a multicenter randomized comparison against oral chemotherapy, autotransplantation was associated with 24% EM. We analyzed trends in outcomes after autologous hematopoietic cell transplantation for AL in North America.

PATIENTS AND METHODS

Between 1995 and 2012, 1,536 patients with AL who underwent autotransplantation at 134 centers were identified in the Center for International Blood and Marrow Transplant Research database. EM and overall survival (OS) were analyzed in three time cohorts: 1995 to 2000 (n = 140), 2001 to 2006 (n = 596), and 2007 to 2012 (n = 800). Hematologic and renal responses and factors associated with EM, relapse and/or progression, progression-free survival and OS were analyzed in more recent subgroups from 2001 to 2006 (n = 197) and from 2007 to 2012 (n = 157).

RESULTS

Mortality at 30 and 100 days progressively declined over successive time periods from 11% and 20%, respectively, in 1995 to 2000 to 5% and 11%, respectively, in 2001 to 2006, and to 3% and 5%, respectively, in 2007 to 2012. Correspondingly, 5-year OS improved from 55% in 1995 to 2000 to 61% in 2001 to 2006 and to 77% in 2007 to 2012. Hematologic response to transplantation improved in the latest cohort. Renal response rate was 32%. Centers performing more than four AL transplantations per year had superior survival outcomes. In the multivariable analysis, cardiac AL was associated with high EM and inferior progression-free survival and OS. Autotransplantation in 2007 to 2012 and use of higher dosages of melphalan were associated with a lowered relapse risk. A Karnofsky score less than 80 and creatinine levels 2 mg/m(2) or greater were associated with worsened OS.

CONCLUSION

Post-transplantation survival in AL has improved, with a dramatic reduction in early post-transplantation mortality and excellent 5-year survival. The risk-benefit ratio for autotransplantation has changed, and randomized comparison with nontransplantation approaches is again warranted.

Aldehyde dehydrogenases in cancer: an opportunity for biomarker and drug development?

Aldehyde dehydrogenases (ALDHs) belong to a superfamily of 19 isozymes that are known to participate in many physiologically important biosynthetic processes including detoxification of specific endogenous and exogenous aldehyde substrates. The high expression levels of an emerging number of ALDHs in various cancer tissues suggest that these enzymes have pivotal roles in cancer cell survival and progression. Mapping out the heterogeneity of tumours and their cancer stem cell (CSC) component will be key to successful design of strategies involving therapeutics that are targeted against specific ALDH isozymes. This review summarises recent progress in ALDH-focused cancer research and discovery of small-molecule-based inhibitors.

Tandem Autologous Stem Cell Transplantation for Multiple Myeloma Patients Based on Response to Their First Transplant-A Prospective Phase II Study

In this prospective phase II clinical trial, multiple myeloma (MM) patients were randomized to receive a second (tandem) autologous stem cell transplantation (ASCT) based on whether they achieved a partial response or worse (≤PR) following initial ASCT (ASCT1). Patients who achieved a very good partial response or better (≥VGPR) had salvage ASCT at relapse. Seventy-five patients received conditioning therapy and ASCT1. A total of 44 patients (59%) achieved ≥VGPR, whereas 31 patients entered ≤PR and were offered tandem ASCT. In all, 20 patients agreed to tandem ASCT. Demographic and clinical characteristics were similar between the two cohorts except for median lactate dehydrogenase (LDH) (P = 0.0141) and percentage of marrow plasma cells before ASCT1 (P = 0.0047), both lower in the ≥VGPR group. Intent to treat analysis showed that patients who achieved ≥VGPR to ASCT1 had a trend toward improved progression-free survival (PFS) (37 vs. 26 months, P = 0.078) and superior overall survival (OS) (not reached vs. 50 months, P = 0.0073). Patients with ≤PR who declined tandem transplantation had shortened PFS (20 vs. 28 months, P = 0.05) but similar OS (53 vs. 57.5 months, P = 0.29) compared to those who received it. Thus, a favorable clinical response to ASCT1 identifies a low-risk group with superior long-term prognosis despite similar PFS.

Multiple myeloma in bisphosphonate-affected jaws--a diagnostic challenge: case report

OBJECTIVE

To discuss the challenges in diagnosis and appropriate management of critical underlying pathoses if a patient presents with signs and symptoms indicative of different conditions that may coexist.

SUMMARY

This case features clinical and radiographic challenges in reaching a diagnosis in a middle- aged man undergoing bisphosphonate therapy for multiple myeloma. The patient had history of bisphosphonaterelated osteonecrosis of the jaw (BRONJ) in the mandible. The patient presented with pain and swelling in the anterior maxilla, associated with paresthesia of upper lip. The radiographic features were suggestive of BRONJ and invasive fungal sinusitis. MRI appearance was suggestive of malignant involvement by plasmacytoma or lymphoma. Although biopsy is usually not advocated in bisphosphonate-affected jaws, it was advised in this case and was positive for multiple myeloma. Vigilance is required to correlate clinical and radiologic findings and further investigations must be considered if malignancy is suspected.

Oral squamous cell carcinoma positive for p16/human papilloma virus in post allogeneic stem cell transplantation: 2 cases and review of the literature

Complications of allogeneic hematopoietic stem cell transplantation (allo-HSCT) includes the risk of secondary malignancies. This may be related to mechanisms including radiation and chemotherapy regimens, chronic graft-versus-host disease, inflammation, and prolonged imunosuppression. Oral squamous cell carcinoma (OSCC) is a complication associated with chronic graft-versus-host disease after allo-HSCT. Although human papillomavirus (HPV) is known to be associated with OSCC, the role of HPV in development of OSCC in post-HSCT patients has not been studied. We identified 2 cases of OSCC in allo-HSCT recipients. Both biopsy specimens tested positive for p16(INK4A), a surrogate marker for HPV. We propose that the association of OSCC and HPV in patients after allo-HSCT may not be incidental. Clinical implications of these cases may imply the need for a HPV screening, early intervention, and consideration of anti-HPV vaccination in this population. The effectiveness of such interventions could be validated in a prospective clinical study.

Salvage second hematopoietic cell transplantation in myeloma

Autologous hematopoietic cell transplantation (AHCT) as initial therapy of patients with multiple myeloma (MM) improves survival. However, data to support this approach for relapsed/progressive disease after initial AHCT (AHCT1) are limited. Using Center for International Blood and Marrow Transplant Research data, we report the outcomes of 187 patients who underwent a second AHCT (AHCT2) for the treatment of relapsed/progressive MM. Planned tandem AHCT was excluded. Median age at AHCT2 was 59 years (range, 28 to 72), and median patient follow-up was 47 months (range, 3 to 97). Nonrelapse mortality after AHCT2 was 2% at 1 year and 4% at 3 years. Median interval from AHCT1 to relapse/progression was 18 months, and median interval between transplantations was 32 months. After AHCT2, the incidence of relapse/progression at 1 and 3 years was 51% and 82%, respectively. At 3 years after AHCT2, progression-free survival was 13%, and overall survival was 46%. In multivariate analyses, those relapsing ≥36 months after AHCT1 had superior progression-free (P = .045) and overall survival (P = .019). Patients who underwent AHCT2 after 2004 had superior survival (P = .026). AHCT2 is safe and feasible for disease progression after AHCT1. In this retrospective study, individuals relapsing ≥36 months from AHCT1 derived greater benefit from AHCT2 compared with those with a shorter disease-free interval. Storage of an adequate graft before AHCT1 will ensure that the option of a second autologous transplantation is retained for patients with relapsed/progressive MM.

Outcomes of salvage autologous versus allogeneic hematopoietic cell transplantation for relapsed multiple myeloma after initial autologous hematopoietic cell transplantation

BACKGROUND

Standard therapy for multiple myeloma (MM) includes initial autologous hematopoietic cell transplantation (autoHCT1) but this is not curative and most patients will relapse. Role of salvage autoHCT2 or allogeneic HCT (alloHCT2) is undefined.

METHODS

MM patients who relapsed after autoHCT1 and had salvage autoHCT2 (N = 27) or alloHCT2 (N = 19) between 1995 - 2011 at our institution were studied retrospectively.

RESULTS

Complete and very good partial remission (CR/VGPR) improved from 7% to 56% after autoHCT2 and from 26% to 37% after alloHCT2. Nonrelapse mortality (NRM) at 3 years was 3.7% for autoHCT2 and 5.3% for alloHCT2 (P = 0.901). Median progression free survival (PFS) and overall survival (OS) for autoHCT2 (19 months, 23 months) and alloHCT2 (6 months, 19 months) were not significantly different. On multivariate analysis, time from autoHCT1 to relapse ≥ 1year (HR 24.81, 95% CI 2.4 - 249.9) and maintenance therapy after autoHCT2 (HR 12.19, 95% CI 2.5 - 249.9) impacted OS after autoHCT2. Time from autoHCT1 to relapse < 1 year vs. ≥ 1 year (HR 18.55, 95% CI 2.28 - 150.57) impacted PFS after autoHCT2. For alloHCT2, no factors impacted NRM, PFS or OS. For those with relapse from autoHCT1 < 1 year vs. ≥ 1 year undergoing autoHCT2, median OS was 15 months (range, 1 - 53) vs. not yet reached at 143 months and median PFS was 5 months (range, 1 - 49) vs. not yet reached at 88 months.

CONCLUSIONS

Salvage autoHCT2 and alloHCT2 are both feasible for post autoHCT1 MM relapse. Relapse ≥ 1 year from autoHCT1 predicts for better PFS and OS after autoHCT2. Maintenance therapy after autoHCT2 is beneficial.

Abstract 3762: The role of aldehyde dehydrogenase isoenzymes in cancer cell proliferation, migration and drug resistance

Aldehyde dehydrogenase (ALDH) proteins are a superfamily of 19 human genes that play crucial role in epithelial cell homeostatsis. Several of these enzymes have been studied in cancer and were shown to protect cells against cytotoxic drugs and oxidative stress in addition to the promotion of cancer cell proliferation and invasion. Our study focuses on 5 less studied isoenzymes (ALDH1B1, ALDH3B1, ALDH4A1, ALDH5A1, and ALDH7A1) using lentiviral mediated overexpression of the enzymes in H1299 lung cancer cell line which is previously known to have negligible amount of ALDH activity. H1299 wild type cells (WT) and cells expressing GFP or RFP were used as controls. Expression of the proteins was confirmed by Western blots and ALDH enzymatic activity assay. We used cell culture, colorimetric MTT assay, wound healing assay, aldefluor assay, colony-forming assay, and in vitro treatment with doxorubicin (Doxo) and 4-hydroperoxycyclophosphaimde (4-HC). All the proteins were highly expressed and resulted in increased ALDH activity detected by using propionaldehyde or benzaldehyde as substrates with NAD+ as a co-factor. The activity of ALDH4A1, 5A1 and 7A1 was not detected by aldefluor flow cytometry assay. Cells expressing ALDH1B1, ALDH4A1 or ALDH7A1 had delayed wound healing at 6 hr, while overall cell proliferation was depressed for ALDH1B1, ALDH3B1 and ALDH5A1 and normal for the other isoenzymes. Cells overexpressing ALDH4A1 or ALDH7A1 showed higher clonal efficiency as well. Only ALDH1B1 and ALDH7A1 showed significant protection against the toxicity of 4-HC (10 μM for 72 hrs) as measured by MTT assay with an increase in average cell survival of 52 and 23%, respectively. Cells overexpressing ALDH5A1 showed significantly increased sensitivity to Doxo (1 and 10 μM for 72 hrs). There was a trend for ALDH7A1 to be protective against Doxo toxicity but did not reach statistical significance. In conclusion, the overexpression of ALDH isoenzymes in this manner may contribute to better understanding of their role in cancer biology and may lead to new cancer treatment approaches that incorporate specific inhibition or stimulation of these enzymes. This is an important goal especially in view of the high ALDH activity in cancer stem cells and their potential contribution to cancer recurrence.

Citation Format: Jan S. Moreb, Mahmoud Mona, Lung-Ji Chang, Yu-Ling Yeh, John Amory, Alex Goldstein. The role of aldehyde dehydrogenase isoenzymes in cancer cell proliferation, migration and drug resistance. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3762. doi:10.1158/1538-7445.AM2013-3762

Regulation of in vitro human T cell development through interleukin-7 deprivation and anti-CD3 stimulation

BACKGROUND

The role of IL-7 and pre-TCR signaling during T cell development has been well characterized in murine but not in human system. We and others have reported that human BM hematopoietic progenitor cells (HPCs) display poor proliferation, inefficient double negative (DN) to double positive (DP) transition and no functional maturation in the in vitro OP9-Delta-like 1 (DL1) culture system.

RESULTS

In this study, we investigated the importance of optimal IL-7 and pre-TCR signaling during adult human T cell development. Using a modified OP9-DL1 culture ectopically expressing IL-7 and Fms-like tyrosine kinase 3 ligand (Flt3L), we demonstrated enhanced T cell precursor expansion. IL-7 removal at various time points during T cell development promoted a slight increase of DP cells; however, these cells did not differentiate further and underwent cell death. As pre-TCR signaling rescues DN cells from programmed cell death, we treated the culture with anti-CD3 antibody. Upon pre-TCR stimulation, the IL-7 deprived T precursors differentiated into CD3+TCRαβ+DP cells and further matured into functional CD4 T cells, albeit displayed a skewed TCR Vβ repertoire.

CONCLUSIONS

Our study establishes for the first time a critical control for differentiation and maturation of adult human T cells from HPCs by concomitant regulation of IL-7 and pre-TCR signaling.

Detection of Skeletal Lesions by Whole Body Multidetector Computed Tomography in Multiple Myeloma has no Impact on Long-Term Outcomes Post Autologous Hematopoietic Cell Transplantation

BACKGROUND

Multiple myeloma (MM), a plasma cell malignancy, is the most common cancer to involve the skeleton. Skeletal related events such as pathologic fractures and lytic bone lesions have been associated with poor prognosis. Whole body multidetector computed tomography (WBCT) has been shown to be the most sensitive imaging modality in detecting small osteolytic lesions (< 5 mm) in the spine. The significance of lytic lesions detected only by CT is unknown as is their impact on overall survival of MM. The aim of this study was to evaluate the impact of lytic bone lesions seen only by WBCT on progression free survival (PFS) and overall survival (OS) in MM patients after hematopoietic cell transplantation (HCT).

METHODS

We evaluated 72 patients who had WBCT and conventional radiographic skeletal survey (CSS) after initial or salvage chemotherapy prior to HCT.

RESULTS

Forty-one patients (57%) had more findings on WBCT than CSS, 31 patients (43%) had no differences in the two imaging techniques, 9 patients had no bone lesions on either modality, and 5 patients had lesions only identified by WBCT and not on CSS. PFS and OS were similar in patients with lesions seen by CSS irrespective of whether additional lesions were noted by WBCT; similarly, in patients without lesions on CSS, OS and PFS were better than patients with lytic lesions, but detection of occult lesions by WBCT did not adversely affect PFS or OS.

CONCLUSIONS

Our study shows that although WBCT is more sensitive in defining existing myelomatous bony disease in MM, these additional findings may not have any impact on PFS and OS of MM patients. Only patients without any bone lesions on conventional skeletal survey had significantly better PFS and OS. This suggests CSS remains the gold standard for evaluating myeloma bone disease.

Lenalidomide after stem-cell transplantation for multiple myeloma

BACKGROUND

Data are lacking on whether lenalidomide maintenance therapy prolongs the time to disease progression after autologous hematopoietic stem-cell transplantation in patients with multiple myeloma.

METHODS

Between April 2005 and July 2009, we randomly assigned 460 patients who were younger than 71 years of age and had stable disease or a marginal, partial, or complete response 100 days after undergoing stem-cell transplantation to lenalidomide or placebo, which was administered until disease progression. The starting dose of lenalidomide was 10 mg per day (range, 5 to 15).

RESULTS

The study-drug assignments were unblinded in 2009, when a planned interim analysis showed a significantly longer time to disease progression in the lenalidomide group. At unblinding, 20% of patients who received lenalidomide and 44% of patients who received placebo had progressive disease or had died (P<0.001); of the remaining 128 patients who received placebo and who did not have progressive disease, 86 crossed over to lenalidomide. At a median follow-up of 34 months, 86 of 231 patients who received lenalidomide (37%) and 132 of 229 patients who received placebo (58%) had disease progression or had died. The median time to progression was 46 months in the lenalidomide group and 27 months in the placebo group (P<0.001). A total of 35 patients who received lenalidomide (15%) and 53 patients who received placebo (23%) died (P=0.03). More grade 3 or 4 hematologic adverse events and grade 3 nonhematologic adverse events occurred in patients who received lenalidomide (P<0.001 for both comparisons). Second primary cancers occurred in 18 patients who received lenalidomide (8%) and 6 patients who received placebo (3%).

CONCLUSIONS

Lenalidomide maintenance therapy, initiated at day 100 after hematopoietic stem-cell transplantation, was associated with more toxicity and second cancers but a significantly longer time to disease progression and significantly improved overall survival among patients with myeloma. (Funded by the National Cancer Institute; ClinicalTrials.gov number, NCT00114101.).

Selective purging of human multiple myeloma cells from autologous stem cell transplantation grafts using oncolytic myxoma virus

Autologous stem cell transplantation and novel therapies have improved overall survival of patients with multiple myeloma; however, most patients relapse and eventually succumb to their disease. Evidence indicates that residual cancer cells contaminate autologous grafts and may contribute to early relapses after autologous stem cell transplantation. Here, we demonstrate that ex vivo treatment with an oncolytic poxvirus called myxoma virus results in specific elimination of human myeloma cells by inducing rapid cellular apoptosis while fully sparing normal hematopoietic stem and progenitor cells. The specificity of this elimination is based on strong binding of the virus to myeloma cells coupled with an inability of the virus to bind or infect CD34(+) hematopoietic stem and progenitor cells. These 2 features allow myxoma to readily identify and distinguish even low levels of myeloma cells in complex mixtures. This ex vivo rabbit-specific oncolytic poxvirus called myxoma virus treatment also effectively inhibits systemic in vivo engraftment of human myeloma cells into immunodeficient mice and results in efficient elimination of primary CD138(+) myeloma cells contaminating patient hematopoietic cell products. We conclude that ex vivo myxoma treatment represents a safe and effective method to selectively eliminate myeloma cells from hematopoietic autografts before reinfusion.

Extramedullary disease in plasma cell myeloma: the iceberg phenomenon

Extramedullary (EM) plasmacytomas (EMPs) that are not progression of intramedullary (IM) plasma cell myeloma (PCM) are usually indolent. In contrast, EM spread of IM PCM is associated with a poor prognosis. The recently introduced Durie-Salmon PLUS staging system includes EM disease in the poor prognosis category. One study noted an increase in EM disease both at diagnosis and during follow-up of PCM in 2000-2007 compared with previous years raising concerns that adoption of novel agents (thalidomide, lenalidomide and bortezomib) and greater use of hematopoietic cell transplantation (HCT) might be contributory to this. It is uncertain if this is a true increase or merely greater detection due to the increasing use of more sensitive imaging techniques (computerized tomography, magnetic resonance imaging and ¹⁸F-fluorodeoxyglucose positron emission tomography) or a reflection of the evolving natural history of PCM in an era when patients are living longer (median overall survival before 1996 was 29.9 months vs 44.8 months after 1996). Recent studies suggest there are important biological differences between PCM with or without EM spread that are offering clues that might explain the propensity for dissemination and a more aggressive clinical course. For example, EM relapse in PCM with and without deletion 13 was 30.8 vs 5.6%, suggesting the biology of a plasma cell subclone before HCT can affect the nature of the relapse after HCT. This article will explore the clinical, biological and treatment implications of EM spread of PCM. In addition, the impact of extramedullary disease on the outcomes of autologous and allogeneic HCT for PCM will be analyzed. Allogeneic HCT early in the course of high-risk PCM with EM disease is a consideration since graft vs myeloma effects may be essential to achieve maximal survival benefits.

The enzymatic activity of human aldehyde dehydrogenases 1A2 and 2 (ALDH1A2 and ALDH2) is detected by Aldefluor, inhibited by diethylaminobenzaldehyde and has significant effects on cell proliferation and drug resistance

There has been a new interest in using aldehyde dehydrogenase (ALDH) activity as one marker for stem cells since the Aldefluor flow cytometry-based assay has become available. Diethylaminobenzaldehyde (DEAB), used in the Aldeflour assay, has been considered a specific inhibitor for ALDH1A1 isoform. In this study, we explore the effects of human ALDH isoenzymes, ALDH1A2 and ALDH2, on drug resistance and proliferation, and the specificity of DEAB as an inhibitor. We also screened for the expression of 19 ALDH isoenzymes in K562 cells using TaqMan Low Density Array (TLDA). We used lentiviral vectors containing the full cDNA length of either ALDH2 or ALDH1A2 to over express the enzymes in K562 leukemia and H1299 lung cancer cell lines. Successful expression was measured by activity assay, Western blot, RT-PCR, and Aldefluor assay. Both cell lines, with either ALDH1A2 or ALDH2, exhibited higher cell proliferation rates, higher clonal efficiency, and increased drug resistance to 4-hydroperoxycyclophosphamide and doxorubicin. In order to study the specificity of known ALDH activity inhibitors, DEAB and disulfiram, we incubated each cell line with either inhibitor and measured the remaining ALDH enzymatic activity. Both inhibitors reduced ALDH activity of both isoenzymes by 65-90%. Furthermore, our TLDA results revealed that ALDH1, ALDH7, ALDH3 and ALDH8 are expressed in K562 cells. We conclude that DEAB is not a specific inhibitor for ALDH1A1 and that Aldefluor assay is not specific for ALDH1A1 activity. In addition, other ALDH isoenzymes seem to play a major role in the biology and drug resistance of various malignant cells.

Severe neutropenia following a prolonged course of vancomycin that progressed to agranulocytosis with drug reexposure

OBJECTIVE

To report a case of severe neutropenia after discontinuing prolonged treatment with vancomycin that progressed to agranulocytosis with vancomycin reexposure.

CASE SUMMARY

A 78-year-old woman presented with severe neutropenia (absolute neutrophil count [ANC] 37 cells/μL) and hypocellular bone marrow with absence of myeloid elements 8 weeks after discontinuing a 3-week treatment course of vancomycin 750 mg every 12 hours. Filgrastim 300 μg daily was started for neutropenia and vancomycin 750 mg every 12 hours and aztreonam 1 g every 8 hours were initiated for catheter-related acute thrombophlebitis of the upper extremity. The patient's ANC decreased to 10 cells/μL within 3 days of starting vancomycin. We suspected an autoimmune process, potentially related to vancomycin exposure, and began treatment with methylprednisolone 1 mg/kg daily. The ANC precipitously dropped to 0 cells/μL despite treatment with steroids and an increased filgrastim dose of 480 μg/day. All antibiotics were discontinued on the fifth day of hospitalization. Within 48 hours, her neutrophil count showed recovery (white blood cell count 500 cells/μL; 10% neutrophils).

DISCUSSION

Idiosyncratic drug-induced agranulocytosis is an uncommon phenomenon but is often associated with serious consequences such as sepsis. We believe this case is unique because of the unusually late neutropenia discovered several weeks after finishing a prolonged course of vancomycin. Furthermore, agranulocytosis developed after unintentional rechallenge with vancomycin. According to the Naranjo probability scale, this case illustrates a probable adverse event caused by vancomycin.

CONCLUSIONS

This case demonstrates a serious adverse event potentially associated with vancomycin use, and calls attention to the safety of rechallenging with vancomycin during a possible drug-induced neutropenia.

Plerixafor in non-Hodgkin’s lymphoma and multiple myeloma patients undergoing autologous stem cell transplantation

Autologous stem cell transplantation (ASCT) is the standard of care for multiple myeloma (MM) and relapsing non-Hodgkin’s lymphoma (NHL) patients. Peripheral blood stem cells (PBSC) have become the main source of grafts for ASCT due to several advantages over bone marrow grafts. Poor PBSC mobilization and inadequate collection of CD34+ cell dose for safe engraftment is a reality for significant proportion of these patients. For this review, we conducted a PubMed search using the titles plerixafor and AMD3100 as well as poor stem cell mobilization. English-language articles were selected and data were extracted with focus on clinical studies of PBSC mobilization in MM and NHL patients. We discuss predictors of poor PBSC mobilization, the impact of poor mobilization on ASCT outcomes, the available agents that have been routinely used to enhance mobilization to achieve optimal CD34+ cell dose, and the role of plerixafor, the first CXCR4 antagonist to be approved for stem cell mobilization. Studies have shown that plerixafor is effective and safe when given with G-CSF either upfront or as a rescue for patients with MM or NHL. Currently, more patients are getting transplanted because of plerixafor. The challenge now is how to use the drug in the most cost effective way. Several scenarios on how to use the drug in proven or predicted poor mobilizers are proposed in this manuscript; however, validation for some of these approaches is still needed.

Plerixafor in non-Hodgkin’s lymphoma and multiple myeloma patients undergoing autologous stem cell transplantation

Autologous stem cell transplantation (ASCT) is the standard of care for multiple myeloma (MM) and relapsing non-Hodgkin’s lymphoma (NHL) patients. Peripheral blood stem cells (PBSC) have become the main source of grafts for ASCT due to several advantages over bone marrow grafts. Poor PBSC mobilization and inadequate collection of CD34+ cell dose for safe engraftment is a reality for significant proportion of these patients. For this review, we conducted a PubMed search using the titles plerixafor and AMD3100 as well as poor stem cell mobilization. English-language articles were selected and data were extracted with focus on clinical studies of PBSC mobilization in MM and NHL patients. We discuss predictors of poor PBSC mobilization, the impact of poor mobilization on ASCT outcomes, the available agents that have been routinely used to enhance mobilization to achieve optimal CD34+ cell dose, and the role of plerixafor, the first CXCR4 antagonist to be approved for stem cell mobilization. Studies have shown that plerixafor is effective and safe when given with G-CSF either upfront or as a rescue for patients with MM or NHL. Currently, more patients are getting transplanted because of plerixafor. The challenge now is how to use the drug in the most cost effective way. Several scenarios on how to use the drug in proven or predicted poor mobilizers are proposed in this manuscript; however, validation for some of these approaches is still needed.

Abstract LB-157: Overcoming T-regulatory effects towards developing a more effective immunotherapy targeting multiple myeloma

Recent progress in dendritic cell (DC) and T cell therapies has offered a new avenue in treating multiple myeloma (MM). We have reported that MM patients' DCs cannot effectively present MM antigens and, instead, preferrentially activate T regulatory cells (Tregs). Furthermore, the MM cells actively suppress patients' DC and T cell functions (Han et al. 2008 Mol Ther. 16, 269–279). Therefore, an effective immunotherapy must overcome immune tolerance to the cancer cells and effectively expand functional MM-specific effector cells. To obtain critical data about MM patient's immune status, a longitudinal study of Treg cells before and after treatments of twenty MM patients was conducted. Patients' bone marrow (BM) and peripheral blood (PB) specimens were collected in the first visit and the follow up visits during treatment. Treg cell populations were examined using antibodies against CD4, CD25, CD127 and Foxp3. At the same time, naïve versus memory phenotype was assessed using antibodies against CD45RA, CCR7 and CD27. Besides the above markers, the surface molecule KLRG1 reflecting T cell senescence and longivity was also detected by flow cytometry. Analysis of Tregs at different time points showed a clear trend of gradual increase in Treg population both in the BM and PB of the MM patients; compared with healthy donors, MM patients' Tregs expand more than two to three folds. Surface marker analysis suggests that the expanded Tregs are mostly memory effector cells, which coincides with a decrease in the ratio of naïve Tregs. Analysis of MM-specific T cell responses by examining effector cytokines and cytolytic activities against autologous tumor cells revealed that BM contained more cytotoxic T cells than did PB. Increased expansion of MM-specific immune effector cells in culture was observed when Treg activities were suppressed using various immune modulators. Further understanding of Treg-mediated cancer tolerance will be essential to develop clinically more effective immunotherapy towards improved survival of MM patients.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-157. doi:10.1158/1538-7445.AM2011-LB-157