Megadose 90Y-ibritumomab tiuxetan prior to allogeneic transplantation is effective for aggressive large B-cell lymphoma.

Allogeneic hematopoietic cell transplantation (allo-HCT) can be curative for relapsed or refractory B-cell lymphomas (BCLs), although outcomes are worse in aggressive disease, and most patients will still experience relapse. Radioimmunotherapy using 90Y-ibritumomab tiuxetan can induce disease control across lymphoma subtypes in a dose-dependent fashion. We hypothesized that megadoses of 90Y-ibritumomab tiuxetan with reduced-intensity conditioning could safely produce deeper remissions in aggressive BCL further maintained with the immunologic effect of allo-HCT. In this phase 2 study, CD20+ BCL patients received outpatient 90Y-ibritumomab tiuxetan (1.5 mCi/kg; maximum, 120 mCi), fludarabine, and then 2 Gy total body irradiation before HLA-matched allo-HCT. Twenty patients were enrolled after a median of 4.5 prior lines of therapy, including 14 with prior autologous transplant and 4 with prior anti-CD19 chimeric T-cellular therapy. A median 90Y-ibritumomab tiuxetan activity of 113.6 mCi (range, 71.2-129.2 mCi) was administered, delivering a median of 552 cGy to the liver (range, 499-2411 cGy). The estimated 1- and 5-year progression-free survival was 55% (95% confidence interval [CI], 31-73) and 50% (95% CI, 27-69) with a median progression-free survival of 1.57 years. The estimated 1- and 5-year overall survival was 80% (95% CI, 54-92) and 63% (95% CI, 38-81) with a median overall survival of 6.45 years. Sixteen patients (80%) experienced grade 3 or higher toxicities, although nonrelapse mortality was 10% at 1 year. No patients developed secondary acute myeloid leukemia/myelodysplastic syndrome. Megadose 90Y-ibritumomab tiuxetan, fludarabine, and low-dose total body irradiation followed by an HLA-matched allo-HCT was feasible, safe, and effective in treating aggressive BCL, exceeding the prespecified end point while producing nonhematologic toxicities comparable to those of standard reduced-intensity conditioning regimens.

Yttrium-90 Anti-CD45 Immunotherapy Followed by Autologous Hematopoietic Cell Transplantation for Relapsed or Refractory Lymphoma.

Autologous hematopoietic cell transplantation (AHCT) is a standard of care for several subtypes of high-risk lymphoma, but durable remissions are not achieved in the majority of patients. Intensified conditioning using CD45-targeted antibody-radionuclide conjugate (ARC) preceding AHCT may improve outcomes in lymphoma by permitting the delivery of curative doses of radiation to disease sites while minimizing toxicity. We performed sequential phase I trials of escalating doses of yttrium-90 (90Y)-labeled anti-CD45 antibody with or without BEAM (carmustine, etoposide, cytarabine, melphalan) chemotherapy followed by AHCT in adults with relapsed/refractory or high-risk B cell non-Hodgkin lymphoma (NHL), T cell NHL (T-NHL), or Hodgkin lymphoma (HL). Twenty-one patients were enrolled (16 NHL, 4 HL, 1 T-NHL). Nineteen patients received BEAM concurrently. No dose-limiting toxicities were observed; therefore, the maximum tolerated dose is estimated to be ≥34 Gy to the liver. Nonhematologic toxicities and engraftment kinetics were similar to standard myeloablative AHCT. Late myeloid malignancies and 100-day nonrelapse deaths were not observed. At a median follow-up of 5 years, the estimates of progression-free and overall survival of 19 patients were 37% and 68%, respectively. Two patients did not receive BEAM; one had stable disease and the other progressive disease post-transplant. The combination of 90Y-anti-CD45 with BEAM and AHCT was feasible and tolerable in patients with relapsed and refractory lymphoma. The use of anti-CD45 ARC as an adjunct to hematopoietic cell transplantation regimens or in combination with novel therapies/immunotherapies should be further explored based on these and other data.

90Y-labeled anti-CD45 antibody allogeneic hematopoietic cell transplantation for high-risk multiple myeloma.

To improve disease control without increasing the toxicity of a reduced-intensity allogeneic hematopoietic cell transplantation (HCT) in multiple myeloma (MM), a phase I trial was performed using an antibody-radionuclide conjugate targeting CD45 (90Y-DOTA-BC8) as conditioning. 90Y-DOTA-BC8 was combined with fludarabine and low-dose TBI followed by allogeneic HCT in patients with MM and ≥1 adverse risk characteristic at diagnosis, relapse after autologous transplant, or plasma cell leukemia (PCL). The primary objective was to estimate the maximum tolerated radiation absorbed dose. Fourteen patients were treated (one with PCL, nine failed prior autologous HCT, and nine with ≥1 adverse cytogenetics). Absorbed doses up to 32 Gy to liver were delivered. No dose-limiting toxicities occurred. Non-hematologic toxicities were manageable and included primarily gastrointestinal (43%) and metabolic/electrolyte disturbances (36%). Treatment-related mortality at 100 days was 0%. At a median follow-up of 5 years, the overall survival was 71% (median not reached) and the progression-free survival was 41% (median 40.9 months). The incorporation of CD45-targeted radioimmunotherapy (RIT) into a reduced-intensity allogeneic HCT is well-tolerated and may induce long-term remissions among patients with poor-risk MM, supporting further development of RIT-augmented conditioning regimens for HCT.

Therapy of Myeloid Leukemia using Novel Bispecific Fusion Proteins Targeting CD45 and 90Y-DOTA.

Pretargeted radioimmunotherapy (PRIT) has been investigated as a multi-step approach to decrease relapse and toxicity for high-risk acute myeloid leukemia (AML). Relevant factors including endogenous biotin and immunogenicity, however, have limited the use of PRIT with an anti-CD45 antibody streptavidin conjugate and radiolabeled DOTA-biotin. To overcome these limitations we designed anti-murine and anti-human CD45 bispecific antibody constructs using 30F11 and BC8 antibodies, respectively, combined with an anti-yttrium (Y)-DOTA single-chain variable fragment (C825) to capture a radiolabeled ligand. The bispecific construct targeting human CD45 (BC8-Fc-C825) had high uptake in leukemia HEL xenografts [7.8 ± 0.02% percent injected dose/gram of tissue (% ID/g)]. Therapy studies showed that 70% of mice with HEL human xenografts treated with BC8-Fc-C825 followed by 44.4 MBq (1,200 µCi) of 90Y-DOTA-biotin survived at least 170 days after therapy, while all nontreated controls required euthanasia because of tumor progression by day 32. High uptake at sites of leukemia (spleen and bone marrow) was also seen with 30F11-IgG1-C825 in a syngeneic disseminated SJL murine leukemia model (spleen, 9.0 ± 1.5% ID/g and bone marrow, 8.1 ± 1.2% ID/g), with minimal uptake in all other normal organs (<0.5% ID/g) at 24 hours after 90Y-DOTA injections. SJL leukemia mice treated with the bispecific 30F11-IgG1-C825 and 29.6 MBq (800 µCi) of 90Y-DOTA-biotin had a survival advantage compared with untreated leukemic mice (median, 43 vs. 30 days, respectively; P < 0.0001). These data suggest bispecific antibody-mediated PRIT may be highly effective for leukemia therapy and translation to human studies.

A phase II trial evaluating the efficacy of high-dose Radioiodinated Tositumomab (Anti-CD20) antibody, etoposide and cyclophosphamide followed by autologous transplantation, for high-risk relapsed or refractory non-hodgkin lymphoma.

Radiation is the most effective treatment for localized lymphoma, but treatment of multifocal disease is limited by toxicity. Radioimmunotherapy (RIT) delivers tumoricidal radiation to multifocal sites, further augmenting response by dose-escalation. This phase II trial evaluated high-dose RIT and chemotherapy prior to autologous stem-cell transplant (ASCT) for high-risk, relapsed or refractory (R/R) B-cell non-Hodgkin lymphoma (NHL). The primary endpoint was progression free survival (PFS). Secondary endpoints were overall survival (OS), toxicity, and tolerability. Patients age < 60 years with R/R NHL expressing CD20 were eligible. Mantle cell lymphoma (MCL) patients could proceed to transplant in first remission. Patients received I-131-tositumomab delivered at ≤25Gy to critical normal organs, followed by etoposide, cyclophosphamide and ASCT. A group of 107 patients were treated including aggressive lymphoma (N = 29), indolent lymphoma (N = 45), and MCL (N = 33). After a median follow-up of 10.1 years, the 10-year PFS for the aggressive, indolent, and MCL groups were 62%, 64%, 43% respectively. The 10-year OS for the aggressive, indolent, and MCL groups were 61%, 71%, 48% respectively. Toxicities were similar to standard conditioning regimens and non-relapse mortality at 100 days was 2.8%. Late myeloid malignancies were seen in 6% of patients. High-dose I-131-tositumomab, etoposide and cyclophosphamide followed by ASCT appeared feasible, safe, and effective in treating NHL, with estimated PFS at 10-years of 43%-64%. In light of novel cellular therapies for R/R NHL, high-dose RIT-containing regimens yield comparable efficacy and safety and could be prospectively compared.

Biokinetics of Radiolabeled Monoclonal Antibody BC8: Differences in Biodistribution and Dosimetry Among Hematologic Malignancies.

We reviewed 111In-DOTA-anti-CD45 antibody (BC8) imaging and bone marrow biopsy measurements to ascertain the biodistribution and biokinetics of the radiolabeled antibody and to investigate differences based on type of hematologic malignancy. Methods: Serial whole-body scintigraphic images (4 time points) were obtained after infusion of the 111In-DOTA-BC8 (176-406 MBq) into 52 adult patients with hematologic malignancies (lymphoma, multiple myeloma, acute myeloid leukemia, and myelodysplastic syndrome). Counts were obtained for the regions of interest for spleen, liver, kidneys, testicles (in men), and 2 marrow sites (acetabulum and sacrum), and correction for attenuation and background was made. Bone marrow biopsies were obtained 14-24 h after infusion, and the percentage of administered activity was determined. Absorbed radiation doses were calculated. Results: Initial uptake in liver averaged 32% ± 8.4% (SD) of administered activity (52 patients), which cleared monoexponentially with a biologic half-time of 293 ± 157 h (33 patients) or did not clear (19 patients). Initial uptake in spleen averaged 22% ± 12% and cleared with a biologic half-time of 271 ± 185 h (36 patients) or longer (6 patients). Initial uptake in kidney averaged 2.4% ± 2.0% and cleared with a biologic half-time of 243 ± 144 h (27 patients) or longer (9 patients). Initial uptake in red marrow averaged 23% ± 11% and cleared with a biologic half-time of 215 ± 107 h (43 patients) or longer (5 patients). Whole-body retention half-time averaged 198 ± 75 h. Splenic uptake was higher in the AML/MDS group than in the lymphoma group (P ≤ 0.05) or the multiple myeloma group (P ≤ 0.10). Liver represented the dose-limiting organ. For liver uptake, no significant differences were observed among the 3 malignancy groups. Average calculated radiation absorbed doses per unit of administered activity for a therapy infusion of 90Y-DOTA-BC8 were 0.35 ± 0.20 cGy/MBq for red marrow, 0.80 ± 0.24 cGy/MBq for liver, 3.0 ± 1.4 cGy/MBq for spleen, 0.055 ± 0.014 cGy/MBq for total body, 0.21 ± 0.15 cGy/MBq for osteogenic cells, and 0.17 ± 0.15 cGy/MBq for kidneys. Conclusion:111In-DOTA-BC8 had a long retention time in liver, spleen, kidneys, and red marrow, and the highest absorbed doses were in spleen and liver. Few differences were observed by malignancy type. The exception was greater splenic uptake in the leukemia/MDS group than in the lymphoma or multiple myeloma group.

Yttrium-90-labeled anti-CD45 antibody followed by a reduced-intensity hematopoietic cell transplantation for patients with relapsed/refractory leukemia or myelodysplasia.

Outcomes of patients with persistent high-risk leukemia or myelodysplasia prior to allogeneic hematopoietic cell transplantation are dismal. We therefore conducted a phase I trial evaluating the use of CD45-targeted radiotherapy preceding hematopoietic cell transplantation with the goal of improving outcomes for this high-risk scenario. Fifteen patients, median age 62 (range 37-76) years, were treated: ten with advanced acute myeloid leukemia, five with high-risk myelodysplastic syndrome. All patients had evidence of disease prior to treatment including nine with marrow blast counts ranging from 7-84% and six with minimal residual disease. Patients received escalating doses of yttrium-90-labeled anti-CD45 antibody followed by fludarabine and 2 Gy total body irradiation prior to human leukocyte antigen-matched, related or unrelated hematopoietic cell transplantation. Although a maximum dose of 30 Gy was delivered to the liver, no dose-limiting toxicity was observed. Therefore, the maximum-tolerated dose could not be estimated. Treatment led to complete remission in 13 patients (87%). All patients engrafted by day 28. Six patients relapsed, median of 59 (range 6-351) days, after transplantation. The 1-year estimate of relapse was 41%. Eight patients (53%) are surviving with median follow up of 1.8 (range 0.9-5.9) years. Estimated overall survival at one and two years was 66% and 46%, respectively, with progression-free survival estimated to be 46% at each time point. In conclusion, the combination of 90Y-DOTA-BC8 with an allogeneic hematopoietic cell transplantation regimen was feasible and tolerable. This approach appears promising in this high-risk leukemia/myelodysplasia patient population with active disease. (Trial registered at clinicaltrials.gov identifier: NCT01300572).

Phase I Study of a CD45-Targeted Antibody-Radionuclide Conjugate for High-Risk Lymphoma.

PURPOSE: External-beam radiation is the single most effective therapy for localized lymphoma. However, toxicity limits its use for multifocal disease. We evaluated CD45 as a therapeutic target for an antibody-radionuclide conjugate (ARC) for the treatment of lymphoma based on its ubiquitous expression, infrequent antigen loss or blockade, and the ability to target minimal disease based on panhematopoietic expression. PATIENTS AND METHODS: We performed a phase I trial of escalating doses of single-agent CD45-targeted ARC based on per-patient dosimetry using the BC8 antibody labeled with iodine-131 (131I) followed by autologous stem cell support in adults with relapsed, refractory, or high-risk B-cell non-Hodgkin lymphoma (B-NHL), T-cell NHL (T-NHL), or Hodgkin lymphoma. The primary objective was to estimate the maximum tolerated radiation absorbed dose. RESULTS: Sixteen patients were enrolled: 7 patients had B-NHL, 6 had Hodgkin lymphoma, and 3 had T-NHL. Median number of prior therapies was three (range: 2-12). Absorbed doses up to 32 Gy to liver were delivered. No dose-limiting toxicities occurred. Nonhematologic toxicity was infrequent and manageable. Objective responses were seen across histologies. Fourteen patients had measurable disease at enrollment, 57% of whom achieved complete remission (CR), including all 3 with T-NHL. Three patients with B-NHL treated among the highest dose levels (26-32 Gy) remain in CR without subsequent therapy 35-41 months later. CONCLUSIONS: CD45-targeted ARC therapy is well-tolerated at doses up to at least 32 Gy to the liver. Objective responses and long-term remissions were observed in patients with relapsed/refractory lymphoma. These data validate continued evaluation of anti-CD45 ARCs in lymphoma.

The α-emitter astatine-211 targeted to CD38 can eradicate multiple myeloma in a disseminated disease model.

Minimal residual disease (MRD) has become an increasingly prevalent and important entity in multiple myeloma (MM). Despite deepening responses to frontline therapy, roughly 75% of MM patients never become MRD-negative to ≤10-5, which is concerning because MRD-negative status predicts significantly longer survival. MM is highly heterogeneous, and MRD persistence may reflect survival of isolated single cells and small clusters of treatment-resistant subclones. Virtually all MM clones are exquisitely sensitive to radiation, and the α-emitter astatine-211 (211At) deposits prodigious energy within 3 cell diameters, which is ideal for eliminating MRD if effectively targeted. CD38 is a proven MM target, and we conjugated 211At to an anti-CD38 monoclonal antibody to create an 211At-CD38 therapy. When examined in a bulky xenograft model of MM, single-dose 211At-CD38 at 15 to 45 µCi at least doubled median survival of mice relative to untreated controls (P < .003), but no mice achieved complete remission and all died within 75 days. In contrast, in a disseminated disease model designed to reflect low-burden MRD, 3 studies demonstrated that single-dose 211At-CD38 at 24 to 45 µCi produced sustained remission and long-term survival (>150 days) for 50% to 80% of mice, where all untreated mice died in 20 to 55 days (P < .0001). Treatment toxicities were transient and minimal. These data suggest that 211At-CD38 offers the potential to eliminate residual MM cell clones in low-disease-burden settings, including MRD. We are optimistic that, in a planned clinical trial, addition of 211At-CD38 to an autologous stem cell transplant (ASCT) conditioning regimen may improve ASCT outcomes for MM patients.

Polatuzumab vedotin or pinatuzumab vedotin plus rituximab in patients with relapsed or refractory non-Hodgkin lymphoma: final results from a phase 2 randomised study (ROMULUS).

BACKGROUND: Antibody-drug conjugates (ADCs) polatuzumab vedotin (pola) and pinatuzumab vedotin (pina) showed clinical activity and tolerability in phase 1 trials. The aim of this multicentre, open-label, phase 2 study was to compare rituximab plus pola (R-pola) or pina (R-pina) in patients with relapsed or refractory diffuse large B-cell lymphoma and follicular lymphoma. METHODS: In this phase 2 randomised study at 39 investigational sites in six countries, patients were randomly assigned (1:1), by use of a dynamic hierarchical randomisation scheme, to receive R-pola or R-pina (375 mg/m2 rituximab plus 2·4 mg/kg ADCs) every 21 days until disease progression or unacceptable toxicity up to 1 year. Treatment allocations were not masked to the investigator, patients or sponsor after the patients were enrolled and randomly assigned. The primary objectives were safety and tolerability, and antitumour response. The study is registered with ClinicalTrials.gov, number NCT01691898, and is closed to accrual. FINDINGS: 81 patients with diffuse large B-cell lymphoma and 42 with follicular lymphoma were recruited between Sept 27, 2012, and Oct 10, 2013, and were assigned to treatment. 81 patients with diffuse large B-cell lymphoma and 41 patients with follicular lymphoma were eligible for analysis. Of the 42 patients with diffuse large B-cell lymphoma who received R-pina, 25 (60%, 95% CI 43-74) achieved an objective response and 11 (26%, 95% CI 14-42) achieved a complete response. Of the 39 patients in this cohort who received R-pola, 21 (54%, 95% CI 37-70) achieved an objective response, and eight (21%, 95% CI 9-36) achieved a complete response. Of the 21 patients in the follicular lymphoma cohort who received R-pina, 13 (62%, 95% CI 38-82) achieved an objective response, and one (5%, 95% CI 0·1-24) achieved a complete response. Of the 20 patients in this cohort who received R-pola, 14 (70%, 95% CI 46-88) achieved an objective response, and nine (45%, 95% CI 23-68) achieved a complete response. In the diffuse large B-cell lymphoma cohort, grade 3-5 adverse events occurred in 33 (79%) of 42 patients receiving R-pina (most common were neutropenia [29%] and hyperglycaemia [10%]; nine [21%] grade 5 adverse events, five of which were infection-related), and in 30 (77%) of 39 patients receiving R-pola (most common were neutropenia [23%], anaemia [8%] and diarrhoea [8%]; no grade 5 adverse events). In the follicular lymphoma cohort, grade 3-5 adverse events occurred in 13 (62%) of 21 patients receiving R-pina (most common were neutropenia [29%] and hyperglycaemia [14%]; no grade 5 adverse events) and in ten (50%) of 20 patients receiving R-pola (most common were neutropenia [15%] and diarrhoea [10%]; one grade 5 adverse event). INTERPRETATION: R-pina and R-pola are potential treatment options in patients with relapsed or refractory diffuse large B-cell lymphoma and follicular lymphoma. Pola was selected by the study funder for further development in non-Hodgkin lymphoma, partly because of longer durations of response than pina, and an overall benefit-risk favouring R-pola. FUNDING: F Hoffmann-La Roche.

Long-Term Follow-Up of 90Y-Ibritumomab Tiuxetan, Fludarabine, and Total Body Irradiation-Based Nonmyeloablative Allogeneic Transplant Conditioning for Persistent High-Risk B Cell Lymphoma.

Nonmyeloablative allogeneic hematopoietic cell transplantation (HCT) can provide prolonged remissions in patients with advanced B cell lymphoma (B-NHL) via the graft-versus-lymphoma effect, although inferior results are seen in patients with chemoresistant, bulky, or aggressive disease. Radioimmunotherapy can safely induce responses in B-NHL with minimal nonhematologic toxicity. Initial results of 90Y-ibritumomab tiuxetan-based allografting demonstrated early safety and disease control in nonremission patients but with short follow-up. Here we report the long-term outcomes of patients treated on this study with specific emphasis on patients achieving early remissions. Eleven of 40 patients were alive at a median follow-up of 9 years (range, 5.3 to 10.2). Fourteen (35%) deaths were due to disease progression and 14 (35%) deaths to complications from HCT. One patient died of a Merkel cell carcinoma. The 5-year overall and progression-free survival for patients with indolent B-NHL was 40% and 27.5%, respectively. None of the patients with diffuse large B cell lymphoma was a long-term disease-free survivor regardless of early remission status. 90Y-ibritumomab tiuxetan-based allografting represents a viable option in patients with indolent histologies. Improved strategies are needed for aggressive B-NHL. The original trial was registered at www.clinicaltrials.gov as NCT00119392.

Bendamustine, etoposide, and dexamethasone to mobilize peripheral blood hematopoietic stem cells for autologous transplantation in non-Hodgkin lymphoma.

BACKGROUND: Bendamustine is a chemotherapeutic agent that has shown broad activity in patients with lymphoid malignancies. It contains both alkylating and nucleoside analog moieties, and thus, is not commonly used for stem cell mobilization due to concerns that it may adversely affect stem cell collection. Here we describe the lymphoma subset of a prospective, non-randomized phase II study of bendamustine, etoposide, and dexamethasone (BED) as a mobilization agent for lymphoid malignancies. METHODS: This subset analysis includes diffuse large B-cell lymphoma (N=3), follicular lymphoma (N=1), primary mediastinal B-cell lymphoma (N=1), and NK/T-cell lymphoma (N=1). Patients received bendamustine (120 mg/m2 IV d 1, 2), etoposide (200 mg/m2 IV d 1-3), and dexamethasone (40 mg PO d 1-4) followed by filgrastim (10 mcg/kg/d sc. through collection). RESULTS: We successfully collected stem cells from all patients, with a median of 7.9×106/kg of body weight (range, 4.4 to 17.3×106/kg) over a median of 1.5 days (range, 1 to 3) of apheresis. All patients who received transplants were engrafted using kinetics that were comparable to those of other mobilization regimens. Three non-hematologic significant adverse events were observed in one patient, and included bacterial sepsis (grade 3), tumor lysis syndrome (grade 3), and disease progression (grade 5). CONCLUSION: For non-Hodgkin lymphoma, mobilization with bendamustine is safe and effective.

cGMP production of astatine-211-labeled anti-CD45 antibodies for use in allogeneic hematopoietic cell transplantation for treatment of advanced hematopoietic malignancies.

The objective of this study was to translate reaction conditions and quality control methods used for production of an astatine-211(211At)-labeled anti-CD45 monoclonal antibody (MAb) conjugate, 211At-BC8-B10, from the laboratory setting to cGMP production. Five separate materials were produced in the preparation of 211At-BC8-B10: (1) p-isothiocyanato-phenethyl-closo-decaborate(2-) (B10-NCS), (2) anti-CD45 MAb, BC8, (3) BC8-B10 MAb conjugate, (4) [211At]NaAt, and (5) 211At-BC8-B10. The 211At-labeling reagent, B10-NCS, was synthesized as previously reported. BC8 was produced, then conjugated with B10-NCS under cGMP conditions to form BC8-B10. [211At]NaAt was produced by α-irradiation of Bi targets, followed by isolation of the 211At using a "wet chemistry" method. The clinical product, 211At-BC8-B10, was prepared by reacting [211At]NaAt with BC8-B10 in NH4OAc buffer (pH 5.5) for 2 min at room temperature, followed by size-exclusion chromatography purification. Quality control tests conducted on the 211At-BC8-B10 included evaluations for purity and identity, as well as pyrogen and sterility tests. Stability of the 211At-BC8-B10 in 25 mg/mL sodium ascorbate solution was evaluated at 1, 2, 4, 6 and 21 h post isolation. For qualification, three consecutive 211At-BC8-B10 clinical preparations were successfully conducted in the cGMP suite, and an additional cGMP clinical preparation was carried out to validate each step required to deliver 211At-BC8-B10 to a patient. These cGMP preparations provided 0.80-1.28 Gbq (21.5-34.5 mCi) of 211At-BC8-B10 with radiochemical purity of >97%. The preparations were found to be sterile and have a pyrogen level <0.50 EU/mL. Cell binding was retained by the 211At-BC8-B10. 211At-BC8-B10 in ascorbic acid solution demonstrated a radiochemical stability of >95% for up to 21 h at room temperature. The experiments conducted have defined conditions for translation of 211At-BC8-B10 production from the laboratory to cGMP suite. This study has allowed the initiation of a phase I/II clinical trial using 211At-BC8-B10 (NCT03128034).

R-CHOP, radioimmunotherapy, and maintenance rituximab in untreated follicular lymphoma (SWOG S0801): a single-arm, phase 2, multicentre study.

BACKGROUND: Despite an abundance of therapeutic options, advanced-stage follicular lymphoma remains incurable. Furthermore, the ideal sequence and absolute benefit of post-induction therapy is unclear. We designed SWOG S0801 to assess the efficacy and safety of consolidative radioimmunotherapy and sequential maintenance rituximab following chemoimmunotherapy. METHODS: For this single-arm, phase 2, multicentre study, we enrolled patients aged 18 years and older with a diagnosis of stage III, IV, or bulky stage II follicular lymphoma, grades 1, 2, or 3a, who had not received previous therapy, from from 20 institutions within the United States National Cancer Institute Clinical Trials Network. Patients were assigned to a 5-year treatment plan consisting of R-CHOP (rituximab plus cyclophosphamide [750 mg/m2], doxorubicin [50 mg/m2], vincristine [1·4 mg/m2], and prednisone or prednisolone [100 mg]) every 21 days for up to six cycles, with rituximab 375 mg/m2 given on day 1 of cycles 1-4, followed by 131iodine tositumomab radioimmunotherapy and subsequent maintenance rituximab 375 mg/m2 within 12 weeks after the sixth cycle of R-CHOP, every 3 months for up to 4 years. The primary endpoint was 3-year progression-free survival in the intention-to-treat population. Efficacy and safety analyses were done in the intention-to-treat population and the per-protocol population. This trial was registered with ClinicalTrials.gov, number NCT00770224. FINDINGS: Between April 1, 2009, and Dec 15, 2010, we enrolled 84 evaluable patients, of whom 73 completed R-CHOP and radioimmunotherapy. Of 69 patients who registered to maintenance therapy, only 41 completed the 4-year rituximab maintenance treatment. Progression-free survival at 3 years was 90% (95% CI 82-95). The most common grade 3 or worse adverse events included neutropenia in 48 (57%) patients, leucopenia in 34 (40%) patients, thrombocytopenia in 17 (20%) patients, and febrile neutropenia in 14 (17%) patients. Nine patients had possible treatment-related deaths during the study from secondary or unknown causes (n=3), cirrhosis (n=1), cardiac arrest (n=1), and secondary malignancies (n=4). Secondary malignancies occurred in seven patients, including two sarcomas, two colorectal carcinomas, two acute myelogenous leukaemias, and one case of renal-cell carcinoma. INTERPRETATION: SWOG S0801 showed near universal responses following chemoimmunotherapy and radioimmunotherapy. However, most discontinuations occurred during maintenance therapy, suggesting that rituximab over a 4-year span is not feasible for many patients. Nonetheless, this sequential therapeutic strategy resulted in good overall outcomes for patients, including a low incidence of early disease progression. FUNDING: The National Cancer Institute and GlaxoSmithKline.

Continued Excellent Outcomes in Previously Untreated Patients With Follicular Lymphoma After Treatment With CHOP Plus Rituximab or CHOP Plus 131I-Tositumomab: Long-Term Follow-Up of Phase III Randomized Study SWOG-S0016.

Purpose SWOG S0016 was a phase III randomized study that compared the safety and efficacy of R-CHOP (rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone) with CHOP-RIT (CHOP followed by consolidation with iodine-133-tositumomab radioimmunotherapy) for previously untreated patients with follicular lymphoma. Understanding the long-term outcome of patients provides a benchmark for novel treatment regimens for FL. Patients and Methods Between 2001 and 2008, 531 previously untreated patients with FL were randomly assigned to receive either six cycles of R-CHOP or six cycles of CHOP-RIT. Patients with advanced-stage disease (bulky stage II, III, or IV) of any pathologic grade (1, 2, or 3) were eligible. Results After a median follow-up of 10.3 years, 10-year estimates of progression-free and overall survival were 49% and 78% among all patients, respectively. Patients in the CHOP-RIT arm had significantly better 10-year progression-free survival compared with patients in the R-CHOP arm (56% v 42%; P = .01), but 10-year overall survival was not different between the two arms (75% v 81%; P = .13). There was no significant difference between the CHOP-RIT and R-CHOP arms in regard to incidence of second malignancies (15.1% v 16.1%; P = .81) or myelodysplastic syndrome or acute myeloid leukemia (4.9% v 1.8%; P = .058). The estimated 10-year cumulative incidences of death resulting from second malignancies were not different (7.1% v 3.2%; P = .16), but cumulative incidence of death resulting from myelodysplastic syndrome or acute myeloid leukemia was higher in the CHOP-RIT arm compared with the R-CHOP arm (4% v 0.9%; P = .02). Conclusion Given these outstanding outcomes, immunochemotherapy should remain the standard induction approach for patients with high-risk FL until long-term follow-up of alternative approaches demonstrates superiority.

Bendamustine with rituximab, etoposide and carboplatin (T(R)EC) in relapsed or refractory aggressive lymphoma: a prospective multicentre phase 1/2 clinical trial.

We sought to develop a safe and effective outpatient salvage regimen by replacing ifosfamide within the (R)ICE (rituximab, ifosfomide, carboplatin, etoposide) regimen with bendamustine (T(R)EC) via a multicentre phase I/II study for patients with relapsed or refractory diffuse large B cell lymphoma (DLBCL) and classic Hodgkin lymphoma (HL). Therapy consisted of 60-120 mg/m2 per day bendamustine on days 1 and 2 in combination with carboplatin, etoposide and rituximab (only for CD20+ lymphoma) used in the (R)ICE regimen for up to 2 cycles. The objectives were to define a maximally tolerated dose (MTD) of bendamustine, determine safety and toxicity, assess efficacy, and evaluate impact on stem cell collection. Forty-eight patients were treated of which 71% had refractory disease. No dose-limiting toxicities were observed. The recommended phase II dose of bendamustine was 120 mg/m2 per day on days 1 and 2. Response rates were 85% (70% complete response, CR) in HL, and 65% (40% CR) in DLBCL. Stem cell collection was successful in 30 of 32 patients. The most common non-haematological toxicities ≥grade 3 were febrile neutropenia (8%) and dehydration (8%). The T(R)EC regimen safely yields high response rates, successfully mobilizes peripheral blood stem cells and compares favourably to RICE, offering an effective outpatient treatment option for patients with relapsed or refractory DLBCL and HL.

CD38-bispecific antibody pretargeted radioimmunotherapy for multiple myeloma and other B-cell malignancies.

Pretargeted radioimmunotherapy (PRIT) has demonstrated remarkable efficacy targeting tumor antigens, but immunogenicity and endogenous biotin blocking may limit clinical translation. We describe a new PRIT approach for the treatment of multiple myeloma (MM) and other B-cell malignancies, for which we developed an anti-CD38-bispecific fusion protein that eliminates endogenous biotin interference and immunogenic elements. In murine xenograft models of MM and non-Hodgkin lymphoma (NHL), the CD38-bispecific construct demonstrated excellent blood clearance and tumor targeting. Dosimetry calculations showed a tumor-absorbed dose of 43.8 Gy per millicurie injected dose of 90Y, with tumor-to-normal organ dose ratios of 7:1 for liver and 15:1 for lung and kidney. In therapy studies, CD38-bispecific PRIT resulted in 100% complete remissions by day 12 in MM and NHL xenograft models, ultimately curing 80% of mice at optimal doses. In direct comparisons, efficacy of the CD38 bispecific proved equal or superior to streptavidin (SA)-biotin-based CD38-SA PRIT. Each approach cured at least 75% of mice at the highest radiation dose tested (1200 µCi), whereas at 600- and 1000-µCi doses, the bispecific outperformed the SA approach, curing 35% more mice overall (P < .004). The high efficacy of bispecific PRIT, combined with its reduced risk of immunogenicity and endogenous biotin interference, make the CD38 bispecific an attractive candidate for clinical translation. Critically, CD38 PRIT may benefit patients with unresponsive, high-risk disease because refractory disease typically retains radiation sensitivity. We posit that PRIT might not only prolong survival, but possibly cure MM and treatment-refractory NHL patients.

Total Body Irradiation Is Safe and Similarly Effective as Chemotherapy-Only Conditioning in Autologous Stem Cell Transplantation for Mantle Cell Lymphoma.

Autologous stem cell transplant (ASCT) consolidation has become a standard approach for patients with mantle cell lymphoma (MCL), yet there is little consensus on the role of total body irradiation (TBI) as part of high-dose transplantation conditioning. We analyzed 75 consecutive patients with MCL who underwent ASCT at our institution between 2001 and 2011 with either TBI-based (n = 43) or carmustine, etoposide, cytarabine, melphalan (BEAM; n = 32) high-dose conditioning. Most patients (97%) had chemosensitive disease and underwent transplantation in first remission (89%). On univariate analysis, TBI conditioning was associated with a trend toward improved PFS (hazard ratio [HR], .53; 95% confidence interval [CI], .28-1.00; P = .052) and similar OS (HR, .59; 95% CI, .26-1.35; P = .21), with a median follow-up of 6.3 years in the TBI group and 6.6 years in the BEAM group. The 5-year PFS was 66% in the TBI group versus 52% in the BEAM group; OS was 82% versus 68%, respectively. However, on multivariate analysis, TBI-based conditioning was not significantly associated with PFS (HR, .57; 95% CI .24-1.34; P = .20), after controlling for age, disease status at ASCT, and receipt of post-transplantation rituximab maintenance. Likewise, early toxicity, nonrelapse mortality, and secondary malignancies were similar in the 2 groups. Our data suggest that both TBI and BEAM-based conditioning regimens remain viable conditioning options for patients with MCL undergoing ASCT.

Preclinical Optimization of a CD20-specific Chimeric Antigen Receptor Vector and Culture Conditions.

Chimeric antigen receptor (CAR)-based adoptive T-cell therapy is a highly promising treatment for lymphoid malignancies, and CD20 is an ideal target antigen. We previously developed a lentiviral construct encoding a third generation CD20-targeted CAR but identified several features that required additional optimization before clinical translation. We describe here several improvements, including replacement of the immunogenic murine antigen-binding moiety with a fully human domain, streamlining the transgene insert to enhance lentiviral titers, modifications to the extracellular IgG spacer that abrogate nonspecific activation resulting from binding to Fc receptors, and evaluation of CD28, 4-1BB, or CD28 and 4-1BB costimulatory domains. We also found that restimulation of CAR T cells with an irradiated CD20 cell line boosted cell growth, increased the fraction of CAR-expressing cells, and preserved in vivo function despite leading to a reduced capacity for cytokine secretion in vitro. We also found that cryopreservation of CAR T cells did not affect immunophenotype or in vivo antitumor activity compared with fresh cells. These optimization steps resulted in significant improvement in antitumor activity in mouse models, resulting in eradication of established systemic lymphoma tumors in 75% of mice with a single infusion of CAR T cells, and prolonged in vivo persistence of modified cells. These results provide the basis for clinical testing of a lentiviral construct encoding a fully human CD20-targeted CAR with CD28 and 4-1BB costimulatory domains and truncated CD19 (tCD19) transduction marker.