Randomized Phase II Trial of Dendritic Cell/Myeloma Fusion Vaccine with Lenalidomide Maintenance after Upfront Autologous Hematopoietic Cell Transplantation for Multiple Myeloma: BMT CTN 1401.

PURPOSE: Vaccination with dendritic cell (DC)/multiple myeloma (MM) fusions has been shown to induce the expansion of circulating multiple myeloma-reactive lymphocytes and consolidation of clinical response following autologous hematopoietic cell transplant (auto-HCT). PATIENTS AND METHODS: In this randomized phase II trial (NCT02728102), we assessed the effect of DC/MM fusion vaccination, GM-CSF, and lenalidomide maintenance as compared with control arms of GM-CSF and lenalidomide or lenalidomide maintenance alone on clinical response rates and induction of multiple myeloma-specific immunity at 1-year posttransplant. RESULTS: The study enrolled 203 patients, with 140 randomized posttransplantation. Vaccine production was successful in 63 of 68 patients. At 1 year, rates of CR were 52.9% (vaccine) and 50% (control; P = 0.37, 80% CI 44.5%, 61.3%, and 41.6%, 58.4%, respectively), and rates of VGPR or better were 85.3% (vaccine) and 77.8% (control; P = 0.2). Conversion to CR at 1 year was 34.8% (vaccine) and 27.3% (control; P = 0.4). Vaccination induced a statistically significant expansion of multiple myeloma-reactive T cells at 1 year compared with before vaccination (P = 0.024) and in contrast to the nonvaccine arm (P = 0.026). Single-cell transcriptomics revealed clonotypic expansion of activated CD8 cells and shared dominant clonotypes between patients at 1-year posttransplant. CONCLUSIONS: DC/MM fusion vaccination with lenalidomide did not result in a statistically significant increase in CR rates at 1 year posttransplant but was associated with a significant increase in circulating multiple myeloma-reactive lymphocytes indicative of tumor-specific immunity. Site-specific production of a personalized cell therapy with centralized product characterization was effectively accomplished in the context of a multicenter cooperative group study. See related commentary by Qazilbash and Kwak, p. 4703.

Myeloablative versus Reduced-Intensity Conditioning for Hematopoietic Cell Transplantation in Acute Myelogenous Leukemia and Myelodysplastic Syndromes-Long-Term Follow-Up of the BMT CTN 0901 Clinical Trial.

Several prospective randomized trials comparing conditioning intensity before allogeneic hematopoietic cell transplantation (HCT) have been performed, with conflicting results. Although reduced-intensity conditioning (RIC) leads to lower treatment-related mortality (TRM), this is offset by higher rates of relapse. Long-term follow-up of randomized comparative trials are limited. Here we present long-term follow-up of a randomized comparison of myeloablative conditioning (MAC) compared with RIC before HCT for acute myelogenous leukemia (AML) or myelodysplasia (MDS). Long-term comparative analyses of overall survival, relapse, and relapse-free survival were performed. Patients age 18 to 65 years with <5% marrow myeloblasts were randomized to receive MAC (n = 135) or RIC (n = 137), followed by HCT from an HLA-matched donor. The primary endpoint of the trial was an 18-month pointwise comparison of overall survival. The analyses were performed using a proportional hazards model. The median follow-up of the entire cohort was 51 months. At 4 years, the transplant-related mortality (TRM) was 25.1% for MAC, compared with 9.9% for RIC (P < .001). Patients who received RIC had a significantly higher risk of relapse compared to those who received MAC (hazard ratio [HR], 4.06; 95% CI, 2.59 to 6.35; P < 0.001). Among the patients who relapsed after HCT, postrelapse survival was similar at 3 years (24% for MAC and 26% for RIC). Overall survival was superior for patients who received MAC compared to those who received RIC (HR, 1.54; 95% CI, 1.07 to 2.2; P = .03). Our data show that patients who received MAC were at higher risk of late TRM compared with those who received RIC; however, because of the exceedingly high rates of relapse in the RIC arm, overall survival remained significantly better for patients who received MAC. Among patients with MDS or AML eligible for either MAC or RIC regimens, long-term follow up demonstrates a survival advantage for patients who received MAC.

Mesenchymal stem cells suppress lymphocyte proliferation in vitro and prolong skin graft survival in vivo.

OBJECTIVE: Mesenchymal stem cells (MSCs), multipotential cells that reside within the bone marrow, can be induced to differentiate into various components of the marrow microenvironment, such as bone, adipose, and stromal tissues. The bone marrow microenvironment is vital to the development, differentiation, and regulation of the lymphohematopoietic system. We hypothesized that the activities of MSCs in the bone marrow microenvironment might also include immunomodulatory effects on lymphocytes. METHODS: Baboon MSCs were tested in vitro for their ability to elicit a proliferative response from allogeneic lymphocytes, to inhibit an ongoing allogeneic response, and to inhibit a proliferative response to potent T-cell mitogens. In vivo effects were tested by intravenous administration of donor MSCs to MHC-mismatched recipient baboons prior to placement of autologous, donor, and third-party skin grafts. RESULTS: MSCs failed to elicit a proliferative response from allogeneic lymphocytes. MSCs added into a mixed lymphocyte reaction, either on day 0 or on day 3, or to mitogen-stimulated lymphocytes, led to a greater than 50% reduction in proliferative activity. This effect could be maximized by escalating the dose of MSCs and could be reduced with the addition of exogenous IL-2. In vivo administration of MSCs led to prolonged skin graft survival when compared to control animals: 11.3 +/- 0.3 vs 7 +/- 0. CONCLUSIONS: Baboon MSCs have been observed to alter lymphocyte reactivity to allogeneic target cells and tissues. These immunoregulatory features may prove useful in future applications of tissue regeneration and stem cell engineering.

Chimerism and clinical outcomes of 110 recipients of unrelated donor bone marrow transplants who underwent conditioning with low-dose, single-exposure total body irradiation and cyclophosphamide.

We hypothesized that low-dose (550-cGy), single-exposure, high dose rate (30 cGy/min) total body irradiation (TBI) with cyclophosphamide as conditioning for HLA-compatible unrelated donor (URD) bone marrow transplantation (BMT) would result in donor chimerism (DC) with a low risk for serious organ toxicity and treatment-related mortality (TRM). Twenty-six patients with good risk diagnoses (acute leukemia in first complete remission [CR] and chronic-phase chronic myelogenous leukemia [CML]) and 84 with poor risk diagnoses underwent this regimen and URD BMT. Unsorted marrow nucleated cells were assessed for chimerism using VNTR probes. All DC occurred in 78 (86%) of 91 evaluable patients at 1 or more follow-up points. Graft failure occurred in 7 (7.7%) patients. Fatal organ toxicity occurred in only 2% of patients. TRM rates through 2 years of follow-up were 19% and 42% in those with good and poor risk diagnoses, respectively. Overall and disease-free survival rates in the good risk group were 47% and 40%, respectively, and in the poor risk group they were 25% and 21%, respectively, at a median follow-up for living patients of 850 days (range, 354-1588 days). This regimen resulted in 100% DC in most patients undergoing URD BMT with a relatively low risk for fatal organ toxicity and TRM.

Primary amyloidosis patients with significant organ dysfunction tolerate autologous transplantation after conditioning with single-dose total body irradiation alone: a feasibility study.

High-dose melphalan has been commonly used as conditioning for amyloidosis with considerable toxicity. We hypothesized that the novel conditioning regimen of 550 cGy total body irradiation (TBI) alone for autologous peripheral blood stem cell transplantation would have reduced organ toxicity and thus permit safer transplantation of primary amyloidosis patients, even those with poor risk disease. The comprehensive regimen included pretransplantation chemotherapy, single-dose TBI alone (550 cGy at 30 cGy/min) conditioning, and post-transplantation interferon-alpha maintenance. Thirteen patients were enrolled in this feasibility study. Patients with multiorgan involvement were included; 10 patients had poor or intermediate risk disease. Cardiac toxicity was significant. Treatment-related mortality through 100 days post-transplantation was 15% and was caused by cardiac mortality. One patient died from arrhythmia after receiving TBI; 2 patients had grade IV cardiac toxicity (with subsequent complete recovery). One patient died 1 month after mobilization from progressive cardiomyopathy and never received conditioning. However, noncardiac organ toxicity was mild. No patient required parenteral nutrition support; no patient developed mucositis; and no patient experienced gastrointestinal bleeding following transplantation. The complete hematologic remission rate was 45%, with pretransplantation chemotherapy being the most active part of the regimen. Survival estimates from enrollment to 1 and 2 years post-transplantation were 66% and 47%, respectively. Causes of death were disease progression (6), myelodysplasia (1), arrhythmia following TBI (1), and congestive heart failure after mobilization (1). In this cohort of primary amyloidosis patients, the transplantation regimen of 550 cGy TBI was feasible and associated with modest treatment-related mortality. Efficacy with TBI conditioning may be reduced compared with high-dose melphalan, but this should be explored in a future trial with a larger cohort of patients.

Phase II study of autologous transplantation with interleukin-2-incubated peripheral blood stem cells and posttransplantation interleukin-2 in relapsed or refractory non-Hodgkin lymphoma.

Previous work suggested that interleukin (IL)-2 can be used for eradicating residual disease in autologous grafts and for preventing recurrence. We report a phase II study of autologous peripheral blood stem cell transplantation with in vitro IL-2 incubation of peripheral blood stem cells and posttransplantation IL-2 in patients with recurrent or refractory non-Hodgkin lymphoma. Salvage chemotherapy consisted of ifosfamide and etoposide. Responding patients underwent autologous peripheral blood stem cell transplantation. IL-2-incubated stem cells were infused on day 0. IL-2 1 mIU/m2 was given from day 1 until day 28. Four monthly maintenance cycles of IL-2 4 mIU/m2 subcutaneously twice daily days 1 to 5 and days 8 to 11 were administered thereafter. Eighty-four evaluable patients were enrolled, and 60 proceeded to transplantation, of which 56 received IL-2-incubated stem cells. The average received dose of posttransplantation IL-2 was 30% to 50% of planned. Only 42 patients received maintenance IL-2. The average received maintenance dose of IL-2 was also approximately 30% of planned. Most dose reductions were due to toxicity or patient refusal. Three-year survival and progression-free survival for all registered patients were 43% (95% confidence interval [CI], 33%-53%) and 31% (95% CI, 21%-41%), respectively. For the 60 patients undergoing transplantation, they were 59% (95% CI, 46%-72%) and 44% (95% CI, 31%-57%), respectively. There was no relation between the dose of IL-2 received and outcome. Survival and disease-free survival of the study group were similar to those of a previous study cohort that received unmanipulated stem cells and no systemic IL-2. Administration of IL-2-incubated peripheral blood stem cells and intensive posttransplantation IL-2 was associated with considerable but rapidly reversible toxicity. No effect on long-term outcome was observed.