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Keywords:

  • myeloma;
  • transplantation;
  • salvage therapy;
  • toxicity

Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SOURCES
  8. REFERENCES

BACKGROUND:

High-dose chemotherapy with autologous hematopoietic cell transplant (auto-HCT) has been shown to improve survival in patients with newly diagnosed multiple myeloma. However, the role of salvage auto-HCT for relapsed patients, particularly in the era of novel therapeutics, is not well defined.

METHODS:

The authors performed a retrospective analysis of all 44 myeloma patients (24 men, 20 women) who received a second auto-HCT as salvage between January 3, 1992 and November 4, 2008 at The University of Texas MD Anderson Cancer Center.

RESULTS:

Median interval between the first and salvage auto-HCT was 30 months (range, 2-78 months). Median age at salvage HCT was 54 years (range, 38-73 years), and median number of salvage treatment regimens was 2 (range, 0-5). Eleven (25%) patients had high-risk chromosomal abnormalities on conventional cytogenetic studies between diagnosis and salvage auto-HCT. Ten patients (23%) experienced grade 3 or higher nonhematologic toxicity after the salvage auto-HCT. One patient died within 100 days, for a treatment-related mortality of 2%. Best responses after salvage chemotherapy + salvage auto-HCT were as follows: complete response (CR) + near CR, 11%; partial response, 79%; overall response rate, 90%. Eighteen (41%) patients received post auto-HCT maintenance therapy. Median follow-up from salvage HCT was 41 months. Kaplan-Meier estimates of median progression-free survival (PFS) and overall survival (OS) from time of salvage auto-HCT were 12.3 and 31.7 months, respectively. Median OS from the time of diagnosis was 75 months. In a fitted Bayesian multivariate model, shorter time to progression after first auto-HCT, greater number of prior therapies, African American race, and immunoglobulin G subtype were significantly associated with worse OS.

CONCLUSIONS:

In selected myeloma patients, a second auto-HCT for salvage therapy is well tolerated, with acceptable toxicity. The overall response rate and PFS are comparable to other salvage regimens. Cancer 2012;3549–3555. © 2011 American Cancer Society.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SOURCES
  8. REFERENCES

Multiple myeloma is the second most common hematologic malignancy in adults, with >20,000 new cases and 10,000 deaths annually in the United States.1 Several studies have supported the use of autologous hematopoietic cell transplant (auto-HCT) in the frontline setting for patients younger than 65 years with good renal function.2-4 However, this procedure is not curative, and the majority of patients inevitably relapse.

The management of patients who relapse after initial treatment with a single auto-HCT is still being debated. Novel agents such as thalidomide, lenalidomide, and bortezomib are active in the salvage setting; however, prolonged treatment can result in significant toxicities, and many current patients have already been treated with these agents in the induction phase. Numerous promising agents are in development, including newer generation immunomodulatory drugs and proteasome inhibitors, histone deacetylase inhibitors, and plasma cell-specific antibodies. However, the use of these is often limited to those patients who can participate in a clinical trial. Despite the use of approved novel agents, the progression-free survival (PFS) in a majority of patients with persistent or refractory disease is only 6 months to 14 months.5, 6 These numbers highlight the need for more effective therapy, especially in patients with good performance status. Several studies suggest that salvage auto-HCT is reasonably safe for selected patients and may grant additional PFS.7-10 In this study, we performed a retrospective review of all 44 patients who have undergone a second, salvage auto-HCT for multiple myeloma at The University of Texas MD Anderson Cancer Center through 2008.

MATERIALS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SOURCES
  8. REFERENCES

Patients

Forty-four patients received a salvage auto-HCT between January 1992 and November 2008. The information from these transplants was prospectively collected in our database and used for the current analysis. Eligible patients had a diagnosis of myeloma and had evidence of relapse (both by International Myeloma Working Group Criteria) after having undergone an auto-HCT. Patients who underwent a second transplant as part of a planned tandem regimen were not included in this study. In general, patients were eligible to receive the second transplant if they had an Eastern Cooperative Oncology Group performance status of <2 and had adequate renal (creatinine ≤2.0), cardiac (left ventricular ejection fraction >45%), pulmonary (diffusing capacity of the lung for carbon monoxide >50%), and hepatic (bilirubin, transaminases <2× upper limit of normal) function.

Hematopoietic Stem Cell Mobilization and Collection

Bone marrow or granulocyte colony-stimulating factor–primed peripheral blood progenitor cells were collected using standard mobilization protocols and apheresis techniques.11 Forty-three patients received a peripheral blood stem cell autograft, whereas 1 patient received a bone marrow–derived graft. Thirty-three patients received stem cells that had been collected before their first auto-HCT, whereas 11 patients underwent a second collection before their salvage auto-HCT. All patients signed written informed consent according to our institutional and the National Marrow Donor Program guidelines. The study was reviewed and approved by the institutional review board at The University of Texas MD Anderson Cancer Center.

Preparative Regimens and Supportive Care

Preparative regimen for the salvage transplant was high-dose melphalan alone (200 mg/m2, n = 21) or a melphalan-based combination (n = 21). Two patients received a combination of thiotepa (750 mg/m2), busulfan (various doses), and cyclophosphamide (120 mg/m2). Melphalan-based combinations used were as follows: 1) melphalan (140 mg/m2) with busulfan (520 mg/m2; n = 2), 2) melphalan (140 mg/m2) with topotecan (17.5 mg/m2) and cyclophosphamide (3 g/m2 n = 6), 3) melphalan (200 mg/m2) with arsenic trioxide (various doses; n = 9), 4) melphalan (200 mg/m2) with arsenic trioxide (various doses) and bortezomib (1 mg/m2 × 3 doses; n = 2), 5) melphalan (120 mg/m2) with busulfan (420 mg/m2) and gemcitabine (150 mg/m2 n = 1), or 6) melphalan (140 mg/m2) with total body irradiation (TBI) (n = 1). Patients received infection prophylaxis with levofloxacin or ciprofloxacin, fluconazole, and acyclovir or valacyclovir. Filgrastim 5 μg/kg was administered subcutaneously daily from day +1 after auto-HCT until the recovery of absolute neutrophil count (ANC) to >0.5 × 109/L for 3 days. Blood products were irradiated and filtered to remove leukocytes before transfusion. After recovery of neutrophil count, patients received infection prophylaxis with sulfamethoxazole-trimethoprim or pentamidine and acyclovir or valacyclovir.

Engraftment and Response

Responses were graded according to International Myeloma Working Group Criteria.12 Initial responses were assessed at approximately day 100 and final, best responses were determined at last follow-up. Neutrophil engraftment was defined as the first of 3 consecutive days with an ANC ≥0.5 × 109/L. Failure to engraft by day 30 was considered primary graft failure. Platelet engraftment was defined as the first of 7 consecutive days with a platelet count of ≥20 × 109/L without transfusion support. Adverse effects were graded according to current National Cancer Institute Common Toxicity Criteria.

Statistical Analysis

Primary endpoints were Kaplan-Meier estimates of overall survival (OS) and PFS. Secondary endpoints were response rate, treatment-related mortality (TRM), and toxicity rates. OS was measured from the day of autologous stem cell infusion (day 0) to death from any cause, with censoring performed at the date of last contact. PFS was determined from the day of stem cell infusion to the day of documented relapse or progression. Death from any cause other than relapse before day 100 was classified as TRM. Patient characteristics were summarized using the median (range) for numerical variables or frequencies (percentages) for categorical variables. Differences in the distributions of patient characteristics between groups were assessed using Wilcoxon, Kruskal-Wallis, or generalized Fisher exact tests.13, 14 Unadjusted probabilities of event times were estimated using the method of Kaplan and Meier.15 The log-rank test16 was used to compare unadjusted OS and PFS between subgroups. Bayesian exponential regression models were used to assess the joint effects of patient covariates on OS, with the best fitting model chosen from the exponential, gamma, inverse gamma, Weibull, and log normal models using the Bayesian information criterion.17 In each multivariate regression model, the covariates included age, sex, race, log(CD34+ cell dose), time to progression (TTP) after first therapy sequence, number of prior therapies before salvage auto-HCT, International Staging System (ISS) stage, immunoglobulin subtype, and date of transplant (before or after January 1, 2003). The interaction terms (race = African American) × (histology = immunoglobulin [Ig] G) and (race = African American) × log(time from first to second stem cell transplant [SCT]) were also included into the model first, but were dropped from the model because they were not significant. The exponential model for OS assumes that the mean OS takes the form μ = exp(m), where m is a linear combination of covariate effects and interactions. We assumed that each parameter in the linear term followed a noninformative normal prior distribution value with mean 0 and variance 1000, and a noninformative gamma prior distribution value for r with mean 1 and variance 1000. All statistical analyses were carried out in Splus 6.1,18 and for the Bayesian model fits, in WinBugs 1.4 (MRC Biostatistics Unit, Cambridge, UK).

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SOURCES
  8. REFERENCES

Patient Characteristics

Patient characteristics are shown in Table 1. Of the 44 patients, 24 were men, and 20 were women. The median age at salvage transplant was 55 years (range, 38-73 years), and the median time between the first auto-HCT and the salvage auto-HCT was 30 months (range, 2-78 years). The median number of therapies received before salvage auto-HCT was 2 (range, 0-5). Eleven patients (25%) had high-risk chromosomal abnormalities on conventional cytogenetic studies at any time between diagnosis and salvage auto-HCT.19 Patients received a mean CD34+ cell dose of 4.1 × 106/kg (standard deviation, 1.8 × 106/kg). Thirty-seven (84%) patients received thalidomide, lenalidomide, or bortezomib in the induction setting, whereas 43 (98%) patients received those agents in the relapsed setting, before the salvage transplant. Fifteen patients (34%) received thalidomide, lenalidomide, or bortezomib maintenance therapy after the second transplant. Eighteen (41%) patients received any type of maintenance therapy.

Table 1. Patient Characteristics
VariablePatients
  1. Abbreviations: HCT, hematopoietic cell transplant; Ig, immunoglobulin; SD, standard deviation.

All patients, No. (%)44 (100)
Sex, No. (%) 
 Female20 (45.5)
 Male24 (54.5)
Race, No. (%) 
 African American8 (18.2)
 Other8 (18.2)
 Caucasian28 (63.6)
Age at salvage HCT, median y [range]54.5 [37.5-72.9]
Time between first and salvage HCT, median mo [range]30 [2-78]
No. of therapies before salvage HCT (after 1st HCT), median [range]2 [0-6]
High-risk cytogenetics, No. (%)11 (25.0)
Durie-Salmon stage, No. (%) 
 I3 (7)
 II13 (26)
 III26 (59)
International staging system stage, No. (%) 
 I10 (22.7)
 II10 (22.7)
 II8 (18.2)
CD34, mean (SD)4.6 (1.8)
Histology, myeloma subtypes, No. (%) 
 IgG28 (63)
 IgA8 (18)
 κ or λ light chain6 (11.4)
 Nonsecretory1 (2.3)
Maintenance with novel agent after salvage HCT, No. (%)15 (34)

Engraftment and Toxicity

Median time to neutrophil and platelet engraftment after the salvage auto-HCT was 10 days (range, 8-14 days) and 11 days (range, 6-398 days), respectively. Of 44 patients, 1 died within 100 days of the salvage transplant, because of supraventricular tachycardia and possible pneumonia, for a TRM of 2%. Ten (23%) patients experienced a grade 3 or higher nonhematologic toxicity, with symptom distributions detailed in Table 2.

Table 2. Grade 3 or Higher Nonhematologic Toxicities During Salvage Autologous Hematopoietic Cell Transplant
Organ SystemPatients, No. (%)Details
All organs10 (23) 
Cardiovascular5 (11)2 tachycardia, 1 hypotension, 1 bradycardia, 1 other
Constitutional0 (0) 
Gastrointestinal3 (7)2 diarrhea, 1 mucositis
Infectious5 (11)5 neutropenic infections
Pulmonary2 (5)1 effusion, 1 pneumonia
Skin1 (2)1 rash
Other0 (0) 

Response and Survival

Five patients (11%) eventually achieved complete response (CR) or very good partial remission, and the best overall response rate (ORR) from the time of relapse was 90%. Two patients (5%) had stable disease, and 1 patient (2%) had progressive disease. Median follow-up time from salvage auto-HCT in surviving patients was 41 months. After salvage auto-HCT, the median PFS was 12.3 months (range, 2 months to 98 months), and the median OS was 31.7 months (range, 0-96 months; Fig. 1). The median OS from time of diagnosis was 74.9 months (range, 25-165 months). In all, 8 patients (18%) had an improvement in their disease status from salvage chemotherapy after the salvage transplant. At last follow-up, 16 patients were alive, and 8 patients were alive who had not progressed.

thumbnail image

Figure 1. Kaplan-Meier plots for overall survival (OS) and progression-free survival (PFS) are shown. Median OS is 31.7 months (95% confidence interval [CI], 21-69); median PFS is 12.3 months (95% CI, 8.3-19.9).

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Prognostic Factors

We studied the impact of age, (log)CD34+ cell dose, TTP after first therapy sequence, number of prior therapies before salvage auto-HCT, sex, race, ISS stage, immunoglobulin subtype, and date of transplant (before or after January 1, 2003) on OS after salvage auto-HCT. The fitted Bayesian multivariate regression model for OS showed that shorter TTP after first transplant, larger number of prior therapies, race being African American, and IgG subtype were significantly associated with worse OS, where a significant effect in the fitted Bayesian model was defined as having a posterior probability of a harmful effect either >.95 or <.05 (Table 3, Fig. 2). There was no significant independent impact of any other factor on the OS, which may be a reflection of a heterogeneous population and relatively small number of events in each group. Detection of high-risk chromosomal abnormalities showed a trend toward a shorter OS (P = .07, data not shown).

thumbnail image

Figure 2. Kaplan-Meier plots show overall survival by immunoglobulin (Ig) subtype and race. Median survival is 8.3 months (95% confidence interval [CI], 6.3-100) for African Americans with non-IgG, 12.2 months (95% CI, 8.1-100) for African Americans with IgG, 36.7 months (95% CI, 21.2-100) for non–African Americans with IgG, and not reached (>100 months) for non–African Americans with non-IgG.

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Table 3. Bayesian Multivariate Analysis of Overall Survival Time (Starting From Second Stem Cell Transplant) Based on the Exponential Distribution (Best Fitting Model for Overall Survival)
FactorsPosterior Quantities
BetaSEHarmful Effect, P
  1. Abbreviations: Ig, immunoglobulin; SE, standard error; TTP, time to progression.

  2. The prior distribution for all covariate parameters is N (0, 100).

Age−0.0330.031.132
Log(CD34)−0.2560.551.33
TTP after 1st−0.3570.214.038
No prior therapy0.3850.145.995
Female0.10.461.588
Black1.0220.517.968
High risk0.1370.651.596
IgG1.0580.605.971
Patients before 2003−0.1840.447.343

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SOURCES
  8. REFERENCES

Despite numerous advances, multiple myeloma remains an incurable disease. Although novel agents and high-dose chemotherapy have improved response rates, patients eventually relapse and die from their disease. Given the rapid development in the field in recent years, we are now faced with the challenge of systematically determining how to best use our tools to improve survival and quality of life.

The idea of using a second, salvage transplant is appropriate, given the data with tandem transplants. In addition, patients who had a durable response to a first transplant may fare best after the salvage transplant.7, 20 For many patients, the issue of a second transplant at relapse is important. For these patients, the results of this study suggest 2 important conclusions: 1) a salvage transplant done at the time of relapse is safe, and 2) the benefit of the salvage transplant is comparable (or potentially superior) to other salvage regimens. In addition, our survival and toxicity data are comparable to published and preliminary reports from several other institutions with similar sample sizes.9, 21-23 Combining the results of our study with those of others, it appears that the salvage transplant is a viable option for select patients.

Another pressing issue facing myeloma physicians is having a long-term treatment plan, as our patients are living longer with their disease. In this setting, it is crucial to offer patients therapies that strike a balance between intensity and duration, such that toxicities can be limited. Although the salvage transplant does have an initial risk of significant toxicity, the potential of having a year or longer without treatment or with low-dose maintenance treatment may be appealing to many patients. In addition, other preparative regimens that build on melphalan may offer an opportunity to enhance the benefit of a salvage auto-HCT. Phase 2 studies combining melphalan with other agents in this patient population are ongoing at our institution.

In interpreting the results from this retrospective analysis, there are certainly limitations. The most obvious of these is a selection bias; more favorable patients were likely recommended for salvage auto-HCT, and thus these results may not be applicable to all patients. In addition, the sample size is small and distributed over >15 years. However, most of the patients did receive novel therapeutics at some point, making these results more pertinent to the contemporary patient population.

Given the relatively small sample size, it is not surprising that most of the prognostic factors studied did not affect OS significantly. The negative impact of shorter TTP and greater number of therapies is consistent with the known biology of the disease. However, the association between African American race and shorter OS is interesting. Although it is known that African Americans are disproportionately affected by multiple myeloma in incidence,24 there is debate over whether there is a difference in outcome in the era of auto-SCT. Preliminary analysis at our institution of all myeloma patients (including those not undergoing auto-SCT) in the era of novel therapeutics suggests that African Americans have a similar OS in comparison to Caucasian patients, but that fewer African Americans undergo auto-SCT.25 Although this is only a small analysis, one could hypothesize that an as yet undetermined factor is linked both to accessibility and success of auto-SCT, which might explain our current and previous findings in African American patients.

Our finding that IgG subtype was associated with a worse OS was also surprising. Although there are few studies examining the prognostic significance of Ig subtype, at least 1 retrospective analysis suggests that IgG subtype is not a poor prognostic indicator in myeloma patients as a whole.26 The relevance of subtype in the setting of second, salvage auto-HCT is less clear and may be an artifact of small sample size.

In deciding whether a salvage transplant for relapsed myeloma is the best treatment choice in comparison with other salvage regimens, the answer remains unclear. The ORR of the second auto-HCT in our study (90%) is comparable to that reported with lenalidomide/dexamethasone27, 28 or bortezomib-containing regimens29-36 for relapsed patients—although the chance of obtaining a CR or very good partial remission is likely greater with lenalidomide or bortezomib chemotherapy combinations. Our ORR also suggests that salvage pharmacotherapy and salvage auto-HCT are not mutually exclusive. The use of novel agents in combination with salvage auto-HCT may offer patients the best chance of response, because 98% of patients received a novel agent as part of their salvage regimen. The PFS in our study is also comparable to those achieved in the lenalidomide and bortezomib combination studies. However, it is hazardous to compare results between all of these studies, as there is marked heterogeneity in how many patients had previously been treated with thalidomide, lenalidomide, or bortezomib.

The ideal study to answer the question of salvage chemotherapy versus salvage auto-HCT would randomize patients to receive either combination chemotherapy only (for example bortezomib/dexamethasone/oral cyclophosphamide) or combination chemotherapy and a second, salvage transplant. In the absence of prospective, multicenter studies, we can turn to smaller, single-center studies. One British group study found no difference in outcomes whether relapsed patients received salvage chemotherapy or salvage auto-HCT.20 However, only a minority of these patients received thalidomide or bortezomib (none received lenalidomide) as part of their salvage therapy.

In conclusion, a second, salvage auto-HCT appears to be a safe and feasible treatment option for select patients with relapsed myeloma. This intervention can yield a durable remission and survival. Thus, patients with relapsed myeloma after a single auto-HCT should be considered for a salvage auto-HCT in an effort to provide an opportunity for a therapy-free interval.

FUNDING SOURCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SOURCES
  8. REFERENCES

No specific funding was disclosed.

CONFLICT OF INTEREST DISCLOSURES

The authors made no disclosures.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. MATERIALS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. FUNDING SOURCES
  8. REFERENCES
  • 1
    Cancer Facts and Figures. Atlanta, GA: American Cancer Society; 2006.
  • 2
    Attal M, Harousseau JL, Stoppa AM, et al. A prospective, randomized trial of autologous bone marrow transplantation and chemotherapy in multiple myeloma. Intergroupe Francais du Myelome. N Engl J Med. 1996; 335: 91-97.
  • 3
    Child JA, Morgan GJ, Davies FE, et al. High-dose chemotherapy with hematopoietic stem-cell rescue for multiple myeloma. N Engl J Med. 2003; 348: 1875-1883.
  • 4
    Palumbo A, Bringhen S, Petrucci MT, et al. Intermediate-dose melphalan improves survival of myeloma patients aged 50 to 70: results of a randomized controlled trial. Blood. 2004; 104: 3052-3057.
  • 5
    Kumar A, Kharfan-Dabaja MA, Glasmacher A, Djulbegovic B. Tandem versus single autologous hematopoietic cell transplantation for the treatment of multiple myeloma: a systematic review and meta-analysis. J Natl Cancer Inst. 2009; 101: 100-106.
  • 6
    Kyle RA, Rajkumar SV. Multiple myeloma. Blood. 2008; 111: 2962-2972.
  • 7
    Tricot G, Jagannath S, Vesole DH, Crowley J, Barlogie B. Relapse of multiple myeloma after autologous transplantation: survival after salvage therapy. Bone Marrow Transplant. 1995; 16: 7-11.
  • 8
    Qazilbash MH, Saliba R, De Lima M, et al. Second autologous or allogeneic transplantation after the failure of first autograft in patients with multiple myeloma. Cancer. 2006; 106: 1084-1089.
  • 9
    Olin RL, Vogl DT, Porter DL, et al. Second auto-SCT is safe and effective salvage therapy for relapsed multiple myeloma. Bone Marrow Transplant. 2009; 43: 417-422.
  • 10
    Mehta J, Tricot G, Jagannath S, et al. Salvage autologous or allogeneic transplantation for multiple myeloma refractory to or relapsing after a first-line autograft? Bone Marrow Transplant. 1998; 21: 887-892.
  • 11
    Rosenbeck LL, Srivastava S, Kiel PJ. Peripheral blood stem cell mobilization tactics. Ann Pharmacother. 2010; 44: 107-116.
  • 12
    Durie BG, Harousseau JL, Miguel JS, et al. International uniform response criteria for multiple myeloma. Leukemia. 2006; 20: 1467-1473.
  • 13
    Randles R, Wolfe D. Introduction to the Theory of Nonparametric Statistics: New York, NY: John Wiley & Sons; 1979.
  • 14
    Fisher R. On the interpretation of χ2 from contingency tables, and the calculation of P. J R Stat Soc. 1922; 85: 87-94.
  • 15
    Kaplan E, Meier P. Nonparametric estimator from incomplete observations. J Am Stat Assoc. 1958; 53: 457-481.
  • 16
    Mantel N. Evaluation of survival data and 2 new rank order statistics arising in its consideration. Cancer Chemother Rep. 1966; 50: 163-170.
  • 17
    Schwarz G. Estimating the dimension of a model. Ann Stat. 1978; 6: 461-464.
  • 18
    Venables WN, Ripley BD. Modern Applied Statistics With S-PLUS. 3rd ed. New York, NY: Springer; 1999.
  • 19
    Munshi NC, Anderson KC, Bergsagel PL, et al. Guidelines for risk stratification in multiple myeloma: report of the International Myeloma Workshop Consensus Panel 2. Blood. 2011; 117: 4696-4700.
  • 20
    Alvares CL, Davies FE, Horton C, Patel G, Powles R, Morgan GJ. The role of second autografts in the management of myeloma at first relapse. Haematologica. 2006; 91: 141-142.
  • 21
    Mikhael JR, Samiee S, Stewart K, et al. Second autologous stem cell transplant (ASCT) as salvage therapy in patients with relapsed multiple myeloma: improved outcomes in patients with longer disease free interval after first ASCT [abstract]. Blood. 2007; 110. Abstract 946.
  • 22
    Simpson L, Verma R, Kumar S, Lacy M, et al. Outcome after second stem cell transplantation for relapsed multiple myeloma [abstract]. J Clin Oncol. 2007; 25. Abstract 8118.
  • 23
    Burzynski JA, Toro JJ, Patel RC, et al. Toxicity of a second autologous peripheral blood stem cell transplant in patients with relapsed or recurrent multiple myeloma. Leuk Lymphoma. 2009: 50: 1442-1447.
  • 24
    Ries LAG, Melbert D, Krapcho M, et al. SEER Cancer Statistics Review, 1975-2005. Bethesda, MD: National Cancer Institute; 2008.
  • 25
    Shah N, Weber D, Alexanian R, et al. Survival disparities between African-American and Caucasian patients with multiple myeloma are blunted in the era of novel therapeutics and autologous stem cell transplantation. Paper presented at: American Society of Hematology Annual Meeting; December 5-8, 2009; New Orleans, La.
  • 26
    Sirohi B, Powles R, Kulkarni S, et al. Comparison of new patients with Bence-Jones, IgG and IgA myeloma receiving sequential therapy: the need to regard these immunologic subtypes as separate disease entities with specific prognostic criteria. Bone Marrow Transplant. 2001; 28: 29-37.
  • 27
    Weber DM, Chen C, Niesvizky R, et al. Lenalidomide plus dexamethasone for relapsed multiple myeloma in North America. N Engl J Med. 2007; 357: 2133-2142.
  • 28
    Dimopoulos M, Spencer A, Attal M, et al. Lenalidomide plus dexamethasone for relapsed or refractory multiple myeloma. N Engl J Med. 2007; 357: 2123-2132.
  • 29
    Richardson PG, Sonneveld P, Schuster MW, et al. Bortezomib or high-dose dexamethasone for relapsed multiple myeloma. N Engl J Med. 2005; 352: 2487-2498.
  • 30
    Richardson PG, Barlogie B, Berenson J, et al. A phase 2 study of bortezomib in relapsed, refractory myeloma. N Engl J Med. 2003; 348: 2609-2617.
  • 31
    Jagannath S, Barlogie B, Berenson J, et al. A phase 2 study of 2 doses of bortezomib in relapsed or refractory myeloma. Br J Haematol. 2004; 127: 165-172.
  • 32
    Orlowski RZ, Nagler A, Sonneveld P, et al. Randomized phase III study of pegylated liposomal doxorubicin plus bortezomib compared with bortezomib alone in relapsed or refractory multiple myeloma: combination therapy improves time to progression. J Clin Oncol. 2007; 25: 3892-3901.
  • 33
    Berenson JR, Yang HH, Vescio RA, et al. Safety and efficacy of bortezomib and melphalan combination in patients with relapsed or refractory multiple myeloma: updated results of a phase 1/2 study after longer follow-up. Ann Hematol. 2008; 87: 623-631.
  • 34
    Davies FE, Wu P, Jenner M, Srikanth M, Saso R, Morgan GJ. The combination of cyclophosphamide, velcade and dexamethasone induces high response rates with comparable toxicity to velcade alone and velcade plus dexamethasone. Haematologica. 2007; 92: 1149-1150.
  • 35
    Kropff M, Bisping G, Schuck E, et al. Bortezomib in combination with intermediate-dose dexamethasone and continuous low-dose oral cyclophosphamide for relapsed multiple myeloma. Br J Haematol. 2007; 138: 330-337.
  • 36
    Reece DE, Rodriguez GP, Chen C, et al. Phase I-II trial of bortezomib plus oral cyclophosphamide and prednisone in relapsed and refractory multiple myeloma. J Clin Oncol. 2008; 26: 4777-4783.