Treatment with ibritumomab tiuxetan radioimmunotherapy in patients with rituximab-refractory follicular non-Hodgkin's lymphoma

Improving the efficacy of radioimmunotherapy for non-Hodgkin lymphomas

Approximately 66,000 Americans develop non-Hodgkin lymphoma (NHL) each year. Although the use of unlabeled antibodies such as rituximab has significantly improved survival when combined with standard chemotherapy regimens, approximately two-thirds of lymphoma patients eventually develop disease recurrence and die of their disease. Novel treatments are urgently needed to cure these patients. One strategy involves the use of radiolabeled immunoconjugates that specifically localize radiation delivery to sites of lymphoma while minimizing toxicity to normal tissues. A growing number of studies support the contention that radiolabeled antibody therapy can improve overall survival of lymphoma patients and lead to durable remissions, with probable cures, in many patients. Various approaches for enhancing the effectiveness of radioimmunoconjugates have been studied, including: use in newly diagnosed lymphoma patients, combination with chemotherapy or other monoclonal antibodies, use with hematopoietic stem cell transplantation, multistep pretargeting strategies to further minimize toxicity, and simultaneous targeting of multiple B-cell antigens. This article summarizes the current knowledge supporting the use of radioimmunotherapy, an underused but effective treatment modality in NHL patients.

Bendamustine: something old, something new

BACKGROUND

Bendamustine (Treanda, Ribomustin) is a water-soluble, bifunctional chemotherapeutic agent that also has potential antimetabolite properties and only partial cross-resistance with other alkylators. Designed in 1963 and re-discovered in 1990s, this drug's unique mechanism of action and favorable side-effect profile promise a major role in the management of lymphoproliferative disorders. Bendamustine has been designated as an orphan drug in the United States, conferring prolonged market exclusivity.

OBJECTIVE

This article provides a comprehensive review of the data on efficacy and toxicity from trials investigating the use of bendamustine for the treatment of lymphoproliferative neoplasms. The pharmacology, pharmacokinetics, and pre-clinical studies with bendamustine are also reviewed.

METHODS

MEDLINE and Pubmed databases (1970-2010) were searched using the terms bendamustine, bendamustin, Treanda, Ribomustin, SDX-105, IMET-3393, and Cytostasan. All relevant articles were reviewed and references screened for additional articles. The databases of the American Society of Hematology (2004-2009) and the American Society of Clinical Oncology (1995-2009) were also searched for relevant abstracts.

RESULTS

Bendamustine induces a remission in more than three-fourths of patients with rituximab-refractory indolent B cell non-Hodgkin lymphoma (NHL). Combined with rituximab in vitro, bendamustine shows synergistic effects against various leukemia and lymphoma cell lines. Clinical trials supporting these results show that bendamustine plus rituximab is highly effective in patients with relapsed-refractory indolent lymphoma, inducing remissions in 90% or more and a median progression-free survival of 23-24 months. Bendamustine has been reasonably well tolerated in clinical trials with low propensity to induce alopecia.

CONCLUSIONS

Combination of bendamustine and rituximab has the potential to become a new standard first-line treatment option for patients with FL, MCL, and indolent lymphomas. Results of ongoing trials will help to further elucidate the optimal role of bendamustine in indolent NHL.

Bendamustine is effective therapy in patients with rituximab-refractory, indolent B-cell non-Hodgkin lymphoma: results from a Multicenter Study

BACKGROUND

Bendamustine hydrochloride is a novel alkylating agent. In this multicenter study, the authors evaluated the efficacy and toxicity of single-agent bendamustine in patients with rituximab-refractory, indolent B-cell lymphoma.

METHODS

Eligible patients (N = 100, ages 31-84 years) received bendamustine at a dose of 120 mg/m(2) by intravenous infusion on Days 1 and 2 every 21 days for 6 to 8 cycles. Histologies included follicular (62%), small lymphocytic (21%), and marginal zone (16%) lymphomas. Patients had received a median of 2 previous regimens (range, 0-6 previous regimens), and 36%were refractory to their most recent chemotherapy regimen. Primary endpoints included overall response rate (ORR) and duration of response (DOR). Secondary endpoints were safety and progression-free survival (PFS).

RESULTS

An ORR of 75% (a 14% complete response rate, a 3% unconfirmed complete response rate, and a 58% partial response rate) was observed. The median DOR was 9.2 months, and median PFS was 9.3 months. Six deaths were considered to be possibly treatment related. Grade 3 or 4 (determined using National Cancer Institute Common Toxicity Criteria [version 3.0.19]. reversible hematologic toxicities included neutropenia (61%), thrombocytopenia (25%), and anemia (10%). The most frequent nonhematologic adverse events (any grade) included nausea (77%), infection (69%), fatigue (64%), diarrhea (42%), vomiting (40%), pyrexia (36%), constipation (31%), and anorexia (24%).

CONCLUSIONS

Single-agent bendamustine produced a high rate of objective responses with acceptable toxicity in patients with recurrent, rituximab-refractory indolent B-cell lymphoma.

Radioimmunotherapy: strategies for the future in indolent and aggressive lymphoma

The conjugation of radioisotopes to monoclonal antibodies, or radioimmunotherapy (RIT), is a highly active treatment in non-Hodgkin's lymphoma. RIT has demonstrated high response rates and durable remissions in extensively pretreated patients and has proved highly effective as consolidation after induction chemotherapy in the first-line therapy of follicular lymphoma. Early-phase clinical trials have shown highly promising results using RIT as part of conditioning regimens in patients who are to undergo transplantation and as consolidation after chemotherapy in patients with aggressive lymphomas. Recent data suggest that integrating RIT with immunochemotherapy and transplant conditioning regimens may further improve outcomes for patients.

Quantitative PCR Analysis for Bcl-2/IgH in a Phase III Study of Yttrium-90 Ibritumomab Tiuxetan As Consolidation of First Remission in Patients With Follicular Lymphoma

Purpose

The randomized First-Line Indolent Trial (FIT) was conducted in patients with advanced follicular lymphoma (FL), to evaluate the safety and efficacy of yttrium-90 (90Y) ibritumomab tiuxetan given as consolidation of complete or partial remission. This study of minimal residual disease was undertaken in parallel, to determine the rate of conversion from bcl-2 polymerase chain reaction (PCR) –detectable to –undetectable status and the corresponding effect on progression-free survival (PFS).

Patients and Methods

Blood samples from 414 patients (90Y-ibritumomab, n = 208; control, n = 206) were evaluated using real-time quantitative polymerase chain reaction (RQ-PCR); 186 were found to have the bcl-2 rearrangement and were thus eligible for inclusion in the RQ-PCR analysis.

Results

Overall, 90% of treated patients converted from bcl-2 PCR–detectable to –undetectable disease status, compared with 36% in the control group. Treatment significantly prolonged median PFS in patients converting to bcl-2 PCR-undetectable status (40.8 v 24.0 months in the control group; P < .01, hazard ratio [HR], 0.399). In patients who had bcl-2 PCR-detectable disease at random assignment, treatment significantly prolonged median PFS (38.4 v 8.2 months in the control group; P < .01, HR, 0.293).

Conclusion

Eradication of PCR-detectable disease occurred more frequently after treatment with 90Y-ibritumomab tiuxetan and was associated with prolongation of PFS.

The distribution of saponins in vivo affects their synergy with chimeric toxins against tumours expressing human epidermal growth factor receptors in mice

BACKGROUND AND PURPOSE

Certain saponins synergize with antitumour drugs to enhance their efficacy, but the mechanisms underlying this synergy in vivo are not well studied. Here, we describe the distribution of Saponinum album (Spn) from Gypsophila paniculata L. in mice after subcutaneous injection.

EXPERIMENTAL APPROACH

The [(3)H]-labelled Spn used for in vivo experiments was biologically active, as it still increased the cytotoxicity of a chimeric toxin in vitro. Distribution of [(3)H]-Spn was measured in BALB/c mice, with or without subcutaneous tumours in the flank. Labelled Spn was subcutaneously injected in the neck, and samples of organs, blood, urine and tumour tissue were analysed for radioactivity, 5-240 min after the injection.

KEY RESULTS

The majority of [(3)H]-Spn distributed within 10 min throughout the entire animal, with high levels of radioactivity in the urine by 30 min. No preferential accumulation in tumour tissue or other organs was observed. In tumour-bearing mice, using a sequential combination of Spn (given first) and a chimeric toxin against the epidermal growth factor receptor, ErbB1, we tested two different pretreatment times for Spn. There was high antitumour efficacy (66% inhibition of tumour growth) after 60 min pre treatment with Spn, but no significant inhibition after 10 min pre treatment with Spn.

CONCLUSIONS AND IMPLICATIONS

[(3)H]-Spn was rapidly cleared from the mice after s.c. injection, and antitumour synergy with chimeric toxins was correlated with the removal of excess Spn from tissues. Disposition of Spn in vivo may critically determine antitumour synergy with chimeric toxins.

A phase 2 study of yttrium-90 ibritumomab tiuxetan (Zevalin) in patients with chronic lymphocytic leukemia

BACKGROUND

Radioimmunotherapy (RIT) with radio-labeled monoclonal antibodies to CD20 produce a high response rate in patients with relapsed lymphoma. Use of this modality in patients with chronic lymphocytic leukemia (CLL) has been hampered by the extensive marrow involvement seen in patients with CLL, which would produce a high risk for marrow aplasia after treatment with RIT. Patients with lymphoma and marrow involvement have been treated with RIT if involved marrow was less than 25% of the total marrow. Thus, we adapted this approach as consolidation therapy in patients with CLL responding to chemoimmunotherapy.

METHODS

Fourteen patients with relapsed CLL either in partial remission or in complete remission but with disease documented by flow cytometry were treated with (90)Y ibritumomab tiuxetan.

RESULTS

One patient responded and achieved a complete remission but with residual disease detected by flow cytometry. Of note was that grade 3 or 4 hematologic toxicity was seen in 12 of the 13 (92%) evaluable patients, with grade 3 or 4 thrombocytopenia noted in 11 (85%) of the patients. In addition, myelosuppression was prolonged with a median duration of grade 3 or 4 thrombocytopenia of 37 days. Five patients had persistent thrombocytopenia 3 months post-therapy.

CONCLUSIONS

Even in patients with CLL and limited marrow involvement, the use of RIT results in unacceptable hematologic toxicity.

The role of bendamustine in the treatment of indolent non-Hodgkin lymphoma

There is no consensus on recommendations for the treatment of relapsed and refractory indolent non-Hodgkin lymphoma (NHL). Bendamustine hydrochloride (bendamustine) has recently been approved for treatment of these patients. Bendamustine is a uniquely structured alkylating agent that lacks cross-resistance with other alkylators. This agent has a high degree of activity against a variety of tumor cell lines. Clinically, bendamustine has demonstrated activity against indolent NHL, chronic lymphocytic lymphoma, multiple myeloma and mantle cell lymphoma. Moreover, studies have validated its activity in patients with indolent NHL who are resistant to purine analogs and rituximab. The cytotoxic activity of bendamustine has been shown to be synergistic with rituximab in hematological malignancies. The incidence of alopecia is significantly less than with other alkylating agents. Myelosuppression is the major toxicity associated with bendamustine.

Phase II Study of Yttrium-90–Ibritumomab Tiuxetan in Patients With Relapsed or Refractory Mantle Cell Lymphoma

Purpose

This phase II trial evaluated the safety and efficacy of yttrium-90 (90Y)–ibritumomab tiuxetan in patients with relapsed or refractory mantle cell lymphoma (MCL).

Patients and Methods

Patients with relapsed or refractory MCL were eligible for the study if they had adequate major organ function and performance status. Those with CNS disease, pleural effusion, circulating lymphoma cells ≥ 5,000/μL, or history of stem-cell transplant were ineligible. Patients with a platelet count ≥ 150,000/μL received a dose of 0.4 mCi/kg of90Y–ibritumomab tiuxetan, whereas those with a platelet count less than 150,000/μL received a dose of 0.3 mCi/kg.

Results

Thirty-four patients with a median age of 68 years (range, 52 to 79 years) received the therapeutic dose. The patients had received a median of three prior treatment regimens (range, one to six treatment regimens), including those that contained rituximab (n = 32) and bortezomib (n = 7). Of the 32 patients with measurable disease, 10 (31%) achieved complete or partial remission. After a median follow-up of 22 months (range, 2 to 72+ months), an intent-to-treat analysis revealed a median event-free survival (EFS) duration of 6 months and an overall survival duration of 21 months. The median EFS for those who achieved partial or complete remission was 28 months, while it was 3 months for those whose disease did not respond (P < .0001); it was 9 months for patients whose tumor measured less than 5 cm in the largest diameter before treatment and 3 months for those whose tumor measured ≥ 5 cm (P = .015).

Conclusion

The single-agent activity of90Y–ibritumomab tiuxetan and its favorable safety profile warrant its further development for the treatment of MCL.

Review of Y-ibritumomab tiuxetan as first-line consolidation radio-immunotherapy for B-cell follicular non-Hodgkin's lymphoma

Several studies have indicated that radioimmunotherapy is an effective and clinically relevant complementary therapeutic approach for patients with B-cell non-Hodgkin's lymphoma (NHL) and may convert partial to complete response when given as consolidation after induction chemotherapy. Yttrium-90((90)Y)-ibritumomab tiuxetan ((90)Y-IT, Zevalin(®), Y2B8) has documented efficacy for both indolent and aggressive NHL. Patients considered eligible for (90)Y-IT treatment should satisfy several screening criteria. A recently completed randomized study for patients with follicular lymphoma has demonstrated that (90)Y-ibritumomab consolidation also produced a marked prolongation of the median time to progression from 13.5 to 37 months, while partial responders seem to derive relatively more benefit. Other published and ongoing studies explore a similar use for patients with aggressive lymphoma. Studies are comparing the use of (90)Y-IT consolidation with the anti-CD20 antibody rituximab maintenance, which is also gaining acceptance. In conclusion, the documented benefit of radioimmunotherapy should be viewed in the context of the goals of treatment and the changing standards of care for lymphoma.

Immunotherapy of cancer

Major advances have been made in the field of immunology in the past two decades. A better understanding of the molecular and cellular mechanisms controlling the immune system has opened the door to many innovative and promising new cancer therapies that manipulate the immune response. For instance, toll-like receptor agonists have been shown to boost immune responses toward tumors. Also, a wide array of cell-based immunotherapies utilizing T cells, NK cells, and dendritic cells have been established. Furthermore, a rapidly expanding repertoire of monoclonal antibodies is being developed to treat tumors, and many of the available antibodies have demonstrated impressive clinical responses. Here, we examine some of these immunotherapeutic approaches currently in use or testing to treat cancer, and we examine available evidence with regards to mechanism and efficacy of these treatments.

The novel expanded porphyrin, motexafin gadolinium, combined with [90Y]ibritumomab tiuxetan for relapsed/refractory non-Hodgkin's lymphoma: preclinical findings and results of a phase I trial

PURPOSE

Therapeutic strategies to enhance the efficacy of radioimmunotherapy have not been explored. Motexafin gadolinium is a novel anticancer agent that targets redox-dependent pathways and enhances sensitivity of tumor cells to ionizing radiation.

EXPERIMENTAL DESIGN

We did preclinical studies examining motexafin gadolinium combined with rituximab and/or radiation in lymphoma cells. We subsequently completed a phase I clinical trial combining escalating doses of motexafin gadolinium concurrently with standard [(90)Y]ibritumomab tiuxetan for patients with relapsed/refractory non-Hodgkin's lymphoma.

RESULTS

In HF1 lymphoma cells, motexafin gadolinium and rituximab resulted in synergistic cytotoxicity (combination index, 0.757) through a mitochondrial-mediated caspase-dependent pathway, whereas cell death in Ramos and SUDHL4 cells was additive. Motexafin gadolinium/rituximab combined with radiation (1-3 Gy) resulted in additive apoptosis. Twenty-eight of 30 patients were evaluable on the phase I clinical trial. Median age was 65 years (47-87 years), and histologies were marginal-zone (n = 1), mantle-cell (n = 3), diffuse large cell (n = 6), and follicular lymphoma (n = 18). Of all patients, 86% were rituximab refractory. Therapy was well tolerated, and no dose-limiting toxicity was seen. Overall response rate was 57% [complete remission (CR), 43%], with median time-to-treatment failure of 10 months (1-48+ months) and median duration-of-response of 17 months. Of note, all responses were documented at 4 weeks. Furthermore, in rituximab-refractory follicular lymphoma (n = 14), overall response rate was 86% (CR, 64%), with a median time-to-treatment failure of 14 months (2-48+ months).

CONCLUSIONS

This represents the first report of a novel agent to be combined safely concurrently with radioimmunotherapy. Furthermore, tumor responses with [(90)Y]ibritumomab tiuxetan/motexafin gadolinium were prompt with a high rate of CRs, especially in rituximab-refractory follicular lymphoma.

Lenalidomide oral monotherapy produces durable responses in relapsed or refractory indolent non-Hodgkin's Lymphoma

PURPOSE

Lenalidomide is a novel immunomodulatory agent with antiproliferative activities. Given its efficacy in a wide range of hematologic malignancies, we conducted a phase II trial (NHL-001) of single-agent lenalidomide in indolent non-Hodgkin's lymphoma (NHL).

PATIENTS AND METHODS

Patients with relapsed/refractory indolent NHL were eligible, with no limit on the number of previous therapies. Oral lenalidomide 25 mg was self-administered once daily on days 1 to 21 of every 28-day cycle for up to 52 weeks as tolerated, or until disease progression. The primary end point was objective response rate (ORR), with secondary end points of duration of response (DR), progression-free survival (PFS), and safety.

RESULTS

Forty-three enrolled patients were assessable for response and safety. Patients received a median of three prior systemic therapies (range, 1 to 17) and half were refractory to last therapy. ORR was 23% (10 of 43), including a 7% complete response (CR) or unconfirmed CR rate. Twenty-seven percent (six of 22) of patients with follicular lymphoma grade 1 or 2, and 22% (four of 18) with small lymphocytic lymphoma responded to therapy. Median DR was not reached, but was longer than 16.5 months with seven of 10 responses ongoing at 15 to 28 months. Median PFS for the whole group was 4.4 months (95% CI, 2.5 to 10.4 months). Adverse events were predictable and manageable; the most common grade 3 or 4 adverse events were neutropenia (30% and 16%, respectively) and thrombocytopenia (14% and 5%, respectively).

CONCLUSION

Oral lenalidomide monotherapy produces durable responses with manageable adverse events in patients with relapsed/refractory indolent NHL, warranting further investigation of treatment for indolent NHL.

Phase I trial of fludarabine, bortezomib and rituximab for relapsed and refractory indolent and mantle cell non-Hodgkin lymphoma

Based on the hypothesis that bortezomib may potentiate fludarabine activity by inhibiting DNA repair, we designed a phase I trial using this combination with rituximab in patients with relapsed and refractory indolent and mantle cell non-Hodgkin lymphoma. Twenty-four patients were enrolled. Non-Hodgkin lymphoma subtypes included 12 patients with follicular lymphoma, four with marginal zone lymphoma, three with lymphoplasmacytic lymphoma, three with mantle cell lymphoma and two with small lymphocytic/chronic lymphocytic leukaemia. Fludarabine and bortezomib were escalated in cohorts of three patients. Rituximab was added to the maximum tolerated dose of fludarabine and bortezomib and added significant dose-limiting myelosuppression. The maximum tolerated dose was fludarabine 25 mg/m(2) on days 1-3, bortezomib 1.3 mg/m(2) on days 1, 4, 8, 11, with rituximab 375 mg/m(2) on day 1 administered every 21 d. Clinical responses were observed in 11 patients, five of whom were refractory to their most recent treatment regimen. Six additional patients had stable disease for a median of 10 months (range 4-30+). Cumulative myelosuppression and neuropathy was observed. The combination of fludarabine, bortezomib, and rituximab appears to be an active regimen with manageable toxicity for relapsed NHL.

Pre-therapy 18F-FDG PET quantitative parameters help in predicting the response to radioimmunotherapy in non-Hodgkin lymphoma

PURPOSE

Radioimmunotherapy (RIT) is a new treatment option for patients with non-Hodgkin lymphoma (NHL). Response to RIT currently remains difficult to predict using conventional prognostic factors and could be refined using functional imaging. The goal of this work is to evaluate the value of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET) in predicting response to Yttrium 90-labeled monoclonal antibodies for patients with NHL.

METHODS

Thirty-five patients with NHL who had undergone (18)F-FDG PET prior to RIT with either (90)Y-ibritumomab tiuxetan (group A; n = 17) or (90)Y-epratuzumab tetraxetan (group B; n = 18) were included in this retrospective study. Four functional criteria were determined for each tumour lesion in a given patient: maximum and mean standard uptake values (SUVmax and SUVmean), functional lesion volume (LVol) and total lesion glycolysis (TLG, product of the volume and the SUVmean). For each patient, we determined highest SUVmax and SUVmean, cumulative TLG (TLGcum) and sum of all LVol (TVol) and compared their predictive value on response (complete or partial response according to IWC) to RIT with those of conventional prognostic factors in group A and B.

RESULTS

A total of 154 lesions were analysed. Nineteen patients (54%) responded to RIT according to IWC. In group A, response rate was 54, 75 and 75% in patients with a SUV max <20 g/ml, a TVol <100 ml and a TLGcum <1060 g, respectively while no patient above these thresholds responded (p < 0.005). In group B, the response rate was 93% for with SUVmax <15 g/ml while no patient above this threshold responded. With TLGcum below 1,360 g, 100% of the patient responded, compared with 37% of patients whose TLGcum was above this threshold (p < 0.05). By contrast, conventional prognostic factors failed to predict response.

CONCLUSIONS

Our preliminary results indicate that pre-therapy (18)F-FDG PET functional parameters such as SUVmax and TLG may help predicting more accurately response to single agent Y90 based RIT.

Effectiveness of Fludarabine, Idarubicin and Cyclophosphamide (FLUIC) Combination Regimen for Young Patients with Untreated Non-Follicular Low-Grade Non-Hodgkin's Lymphoma

In the last years, fludarabine (FLU) alone or in combination with other drugs has been reported to be effective in the treatment of previously untreated low-grade non-Hodgkin's lymphomas (LG-NHL). We report on the therapeutic efficacy and toxicity of a combination of FLU, idarubicin and cyclophosphamide (FLUIC regimen) in untreated non-follicular LG-NHL. We administered a three-drug combination of FLU (25 mg/m2 i.v. on days 1 to 3), idarubicin (14 mg/m2 i.v. on day 1) and cyclophosphamide (200 mg/m2 i.v. on days 1 to 3) to treat 41 young, previously untreated patients with non-follicular LG-NHL. Chemotherapy was repeated every 4 weeks for a total of 6 cycles. Among 41 patients, 24 (59%) were diagnosed with small lymphocytic, 10 (24%) with immnocytoma, and 7 (17%) with marginal zone subtypes. Nineteen (46%) patients achieved complete response (CR) and 21 (51%) partial response, while the remaining 1 (3%) showed no benefit from the treatment. With respect to histology, we observed CR rates of 38% for the small lymphocytic subtype, 40% for the immunocytoma subtype, and 86% for the marginal zone subtype. Estimated 42-month overall survival and relapse-free survival rates were 64% and 100%, respectively. Hematologic grade 3-4 toxicity was seen in 9 (22%) patients; no opportunistic infection or death was associated with administration of the FLUIC regimen. These preliminary data suggest that FLUIC is a very active, well-tolerated regimen for young, untreated patients with advanced non-follicular LG-NHL.

Recent advances in the treatment of follicular lymphoma

The success of anti-CD20 monoclonal antibody therapy for follicular lymphoma has encouraged efforts to identify new target molecules, and a new generation of more potent antibodies is now being developed, targeting either CD20 or other molecules. At the same time, other agents that were developed to treat other kinds of malignancies have turned out to be effective against this disease. In both treatment approaches, using either antibodies or chemical compounds, data on such trials are accumulating. In this mini-review these agents are introduced, and it is noted that clinical trials of these new agents are also ongoing in Japan.

Radioimmunotherapy and stem-cell transplantation in the treatment of aggressive B-cell lymphoma

High-dose chemotherapy and autologous stem-cell transplantation (ASCT) have an established therapeutic role in the treatment of chemo-sensitive relapsed aggressive lymphoma, but has limited success in chemo-refractory disease or in heavily pretreated, multiple relapsed patients. Recurrent disease is the major cause of treatment failure in all patient subsets and the majority is not cured. Methods for better eradication of underlying lymphoma are needed to improve outcome. Radioimmunotherapy (RIT) combines radiation delivered by radio-isotopes with the targeting effect of monoclonal antibodies. Two radioimmunoconjugates are currently approved for relapsed/resistant low-grade or transformed lymphoma: iodine-131 tositumomab and yttrium-90 ibritumomab tiuxetan. These agents are also effective in aggressive lymphoma. Radio-labeled antibodies are ideal candidates to combine with high-dose chemotherapy and ASCT. Their major toxicity is myelosuppression, which is easily reversed by ASCT and they can target disease sites with almost no added toxicity to normal tissues. RIT has been used in escalated doses as the sole treatment prior to ASCT or in standard or escalated doses combined with standard high-dose chemotherapy regimens. RIT was also combined with reduced-intensity conditioning and allogeneic SCT. Preliminary results are promising and suggest improved disease control with no added toxicity; however randomized studies are needed to confirm these initial observations.

Yttrium 90 ibritumomab tiuxetan in lymphoma

Radioimmunoconjugates are radioisotope-bound monoclonal antibodies that target radiation specifically to sites of lymphoma involvement. Initial studies of 90Y-ibritumomab tiuxetan in non-Hodgkin's lymphoma (NHL) have suggested benefit in patients with relapsed or refractory indolent disease. However, the routine adoption of this agent is tempered by concerns of associated toxicities and unclear long-term benefit. A comprehensive search for studies on 90Y-ibritumomab tiuxetan use in lymphoma was completed. The aims of this systematic review were to summarize and evaluate the evidence on: (1) the benefits and risks of this novel therapy; (2) predictors for response and toxicity; and (3) the role of dosimetry and imaging studies prior to treatment. A total of twenty trials investigating the use of 90Y-ibritumomab tiuxetan for the treatment of adult patients with NHL were identified. In trials of patients with relapsed or refractory indolent NHL, overall response rates ranged from 67 - 83%. In patients with follicular NHL refractory to the monoclonal antibody, rituximab, response rates remained high (74%). However, in rituximab-naïve patients with relapsed or refractory indolent or transformed NHL, the higher response rate seen with 90Y-ibritumomab tiuxetan therapy compared to rituximab monotherapy has not translated into clear improvements in time-to-progression or survival. 90Y-ibritumomab tiuxetan is an active agent in relapsed and refractory non-Hodgkin's lymphoma that should be considered in select patients.

Treatment with yttrium 90 ibritumomab tiuxetan at early relapse is safe and effective in patients with previously treated B-cell non-Hodgkin's lymphoma

Yttrium 90 ((90)Y) ibritumomab tiuxetan (Zevalin), a radiolabeled monoclonal antibody against the CD20 antigen, is indicated for the treatment of patients with relapsed or refractory low-grade, follicular, or transformed B-cell non-Hodgkin's lymphoma (NHL), including patients with rituximab-refractory follicular NHL. Data on 211 patients treated in four clinical trials were analysed to compare the efficacy and safety of (90)Y ibritumomab tiuxetan when it was used after the first relapse of NHL and when it was used after two or more prior therapies. Sixty-three patients (30%) were treated with (90)Y ibritumomab tiuxetan after their first relapse and 148 (70%) after two or more prior therapies. Demographics, disease characteristics and the frequency of adverse events were similar in all groups, with the exception of a higher rate of marrow involvement in first-relapse patients than in patients with two or more prior therapies (57% vs. 39%; P < 0.05). The complete response rate [confirmed (CR) and unconfirmed (Cru)] was higher in first-relapse patients (49% vs. 28%; P < 0.01), and the median time to progression (TTP) was longer (12.6 vs. 7.9 months; P < 0.05). In patients with follicular NHL, the differences were even more pronounced (CR/CRu: 51% vs. 28%; P < 0.01; TTP: 15.4 vs. 9.2 months; P < 0.05). (90)Y ibritumomab tiuxetan has substantial clinical benefits as a second-line therapy, especially in patients with follicular NHL. The quality of disease remissions obtained when (90)Y ibritumomab tiuxetan is administered after first relapse appears to be comparable with that observed with most chemotherapy regimens in first-relapse patients.

Retreatment with yttrium-90 ibritumomab tiuxetan in patients with B-cell non-Hodgkin's lymphoma

There is no data on safety and efficacy of a second course of ibritumomab tiuxetan. In this work, data on patients with B-cell NHL who were treated with two courses of ibritumomab tiuxetan were analyzed. Eighteen such patients were analyzed (age: 58 years, 48 - 91), with a median of four prior regimens (1 - 7), stem cell transplantation (n = 5), and radiation therapy (n = 6). After the first course, G3/4 neutropenia and thrombocytopenia was 35% and 41%; overall response rate (ORR) was 89%; time between courses was 16.6 months (6.0 - 42.7). After the second course, the incidence of G3/4 neutropenia and thrombocytopenia was 28% and 44%; and ORR 77%. There were no infectious or bleeding complications, secondary myelodysplastic syndromes, or leukemias. Retreatment with the ibritumomab tiuxetan regimen was well tolerated, with a safety profile similar to that of the first course. To conclude, patients who benefited from the first course of ibritumomab tiuxetan can benefit from retreatment.

Phase I trial of 90Y-ibritumomab tiuxetan in patients with relapsed B-cell non-Hodgkin's lymphoma following high-dose chemotherapy and autologous stem cell transplantation

Between January 2001 and September 2005, 19 patients with progressive B-cell non-Hodgkin's lymphoma were treated with a cohort-specific dose of yttrium-90 ibritumomab tiuxetan (0.10 - 0.20 mCi/kg) to determine appropriate dosing in patients who had previously received high-dose chemotherapy and autologous stem cell transplantation (ASCT). Patients were required to have adequate end organ function and bone marrow status. Patients had been treated with a median of three prior therapies (range, 1 - 9). The median time from ASCT to radioimmunotherapy was 28 months. Hematologic toxicities were dose-limiting and included grade 3 - 4 thrombocytopenia (53%), neutropenia (32%), and anemia (21%). The majority of grade 3 - 4 events occurred at the 0.2 mCi/kg dose level. Nine patients responded (complete response, complete response unconfirmed, or partial response) to the therapy. At a median follow-up of 37 months, the 1-year event-free and overall survival rates were 26% and 57%, respectively. A dose of 0.2 mCi/kg ibritumomab tiuxetan is safe and effective for patients with progressive disease after high-dose chemotherapy and ASCT.

Yttrium-90-ibritumomab tiuxetan in combination with intravenous busulfan, cyclophosphamide, and etoposide followed by autologous stem cell transplantation in patients with relapsed or refractory B-cell non-Hodgkin's lymphoma

BACKGROUND

Radiolabelled immunotherapy agents have an increasingly significant role in autologous stem cell transplantation (ASCT) by improving the tolerability and increasing the efficacy of the conditioning regimen, thereby reducing the relapse risk. We evaluated the efficacy and safety of yttrium-90-ibritumomab tiuxetan ((90)Y-ibritumomab) combined with intravenous busulfan, cyclophosphamide, and etoposide (Bu/Cy/E) followed by ASCT in patients with relapsed or refractory B-cell non-Hodgkin's lymphoma (NHL).

METHODS

Each patient received a single dose of (90)Y-ibritumomab (0.4 mCi/kg on day -14) with Bu/Cy/E as a conditioning regimen.

RESULTS

The patient cohort consisted of 19 individuals (ten males), of median age 51 years (range, 25-63 years). Sixteen patients had received two or more chemotherapy regimens before transplantation. Histologies were diffuse large B-cell (n = 14), follicular (n = 2), mantle cell (n = 2), and Burkitt lymphoma (n = 1). All patients engrafted. The median time to neutrophil engraftment was 10 days and time to platelet engraftment was 10 days. Nineteen patients were evaluable for response. The objective overall response rate was 84.2% (16/19): continued CR, 36.8% (7/19); induced CR, 36.8% (7/19); and PR, 10.5% (2/19). With a median follow-up of 29.4 months (13.4-36.6), the estimated 3-year overall survival and event-free survival rates were 52.6% (95% confidence interval [CI] 45.8-59.4) and 26.3% (95% CI 19.8-32.8), respectively. Adverse events were similar to those seen historically with Bu/Cy/E alone, and there were no treatment related deaths.

CONCLUSION

In conclusion, (90)Y-ibritumomab with Bu/Cy/E and ASCT is feasible in patients with relapsed or refractory B-cell NHL, without increased toxicity.

Absorbed dose and biologically effective dose in patients with high-risk non-Hodgkin's lymphoma treated with high-activity myeloablative 90Y-ibritumomab tiuxetan (Zevalin)

PURPOSE

The aim of this study was to carry out two different dose estimation approaches in patients with non-Hodgkin's lymphoma (NHL) treated with a myeloablative amount of (90)Y-labelled ibritumomab tiuxetan (Zevalin(R)) in an open-label dose escalation study.

METHODS

Twenty-seven patients with relapsed/refractory or de novo high-risk NHL receiving one myeloablative dose of (90)Y-ibritumomab tiuxetan followed by tandem stem cell reinfusion were evaluated for dose estimate. The injected activity was 30 MBq/kg in 12 patients and 45 MBq/kg in 15 patients. Dose estimation was performed 1 week prior to (90)Y-ibritumomab tiuxetan by injection of (111)In-ibritumomab tiuxetan (median activity: 200 MBq). The absorbed dose (D) and the biologically effective dose (BED) were calculated.

RESULTS

The absorbed doses per unit activity (Gy/GBq) were [median (range)]: heart wall 4.6 (2.5-9.7), kidneys 5.1 (2.8-10.5), liver 6.1 (3.9-10.4), lungs 2.9 (1.5-6.8), red marrow 1.0 (0.5-1.7), spleen 7.0 (1.5-14.4) and testes 4.9 (2.9-16.7). The absorbed dose (Gy) for the 15 patients treated with 45 MBq/kg were: heart wall 17.0 (8.7-25.4), kidneys 17.1 (7.9-22.4), liver 20.8 (15.4-28.3), lungs 8.1 (5.4-11.4), red marrow 3.1 (2.0-4.0), spleen 26.2 (17.0-35.6) and testes 17.3 (9.0-28.4). At the highest activities the acute haematological toxicity was mild or moderate and of very short duration, and it was independent of the red marrow absorbed dose. No secondary malignancy or treatment-related myelodysplastic syndrome was observed. No non-haematological toxicity (liver, kidney, lung) was observed during a follow-up period of 24-48 months.

CONCLUSION

The use of 45 MBq/kg of (90)Y-ibritumomab tiuxetan in association with stem cell autografting resulted in patients being free of toxicity in non-haematological organs. These clinical findings were in complete agreement with our dose estimations, considering both organ doses and BED values.

A phase I study of a combination of yttrium-90-labeled anti-carcinoembryonic antigen (CEA) antibody and gemcitabine in patients with CEA-producing advanced malignancies

PURPOSE

To determine the maximum tolerated dose of combined therapy using an yttrium-90-labeled anti-carcinoembryonic antigen (CEA) antibody with gemcitabine in patients with advanced CEA-producing solid tumors.

EXPERIMENTAL DESIGN

The chimeric human/murine cT84.66 is an anti-CEA intact IgG1, with high affinity and specificity to CEA. This was given at a fixed yttrium-90-labeled dose of 16.6 mCi/m(2) to subjects who had and an elevated CEA in serum or in tumor by immunohistochemistry. Also required was a tumor that imaged with an (111)In-labeled cT84.66 antibody. Patients were treated with escalating doses of gemcitabine given i.v. over 30 minutes on day 1 and 3 after the infusion of the yttrium-90-labeled antibody. Patients were treated in cohorts of 3. The maximum tolerated dose was determined as the highest level at which no >1 of 6 patients experienced a dose limiting toxicity.

RESULTS

A total of 36 patients were enrolled, and all but one had prior systemic therapy. The maximum tolerated dose of gemcitabine in this combination was 150 mg/m(2). Dose limiting toxicities at a gemcitabine dose of 165 mg/m(2) included a grade 3 rash and grade 4 neutropenia. One partial response was seen in a patient with colorectal cancer, and 4 patients had a >50% decrease in baseline CEA levels associated with stable disease. Human antichimeric antibody responses were the primary reason for stopping treatment in 12 patients.

CONCLUSIONS

Feasibility of combining gemcitabine with an yttrium-90-labeled anti-CEA antibody is shown with preliminary evidence of clinical response.

[New clinical technologies in drug development]

The integration of functional imaging and therapeutic nuclear medicine technologies mainly in the early phases of drug development (clinical technologies implementation, CTI) is a relatively young option, which has amply influenced drug development concepts in the pharmaceutical industry. Over the past 15 years, the greatest risk reduction in drug development decision making has resulted from the earlier involvement of drug metabolism in the optimization stage of drug design rather than the late-stage characterization of target molecules. Go/no-go decisions of drug development programs and drug dosage can also be inferred from these techniques, which lead to decreases in time and costs. Not only is CTI effectively used in early drug development, but also in later clinical study phases (phases 3b/4) as a therapy monitoring or follow-up instrument. In addition, CTI is interesting and promising for the development of new therapy concepts in nuclear medicine which involve the application of monoclonal antibodies and peptides for treatment of different hematologic-oncologic diseases.

Bendamustine: Rebirth of an Old Drug

Bendamustine is a unique cytotoxic agent with structural similarities to alkylating agents and antimetabolites, but which is non–cross-resistant with alkylating agents and other drugs in vitro and in the clinic. Early clinical studies conducted in the German Democratic Republic more than 30 years ago suggested promising activity in indolent non-Hodgkin's lymphoma (NHL). Two North American trials reported responses in more than 70% of patients with chemotherapy- and rituximab-refractory disease, suggesting that bendamustine may be the most effective drug available for this patient population. Response rates of 90% to 92%, with complete remission in 55% to 60%, have been reported in patients with follicular and mantle-cell lymphoma with the combination of bendamustine and rituximab. Superiority over chlorambucil in previously untreated patients with chronic lymphocytic leukemia (CLL) led to its recent approval for this disease in the United States. Bendamustine is approved in Germany for the treatment of patients with indolent NHL, CLL, and multiple myeloma. Activity has also been noted in patients with breast cancer and small-cell lung cancer. Questions related to the optimization of bendamustine therapy, including dose and schedule, role relative to other available agents, and management of toxicities, are being investigated. However, the availability of bendamustine provides another effective treatment option for patients with lymphoid malignancies.

Update on the rational use of Y-ibritumomab tiuxetan in the treatment of follicular lymphoma

The development of radiolabeled antibodies against CD20 has facilitated targeted treatment of follicular lymphoma (FL). By using (90)Y-ibritumomab tiuxetan (Zevalin((R))), a radionuclide (yttrium-90, linked by the chelator tiuxetan to the antibody ibritumomab) is brought into the vicinity of lymphoma cells. By the so-called cross-fire effect, this beta emitter has the capacity to destroy not only the lymphoma cells having bound the antibody, but also neighboring lymphoma cells. Currently this antibody is licensed in the European Union for use in relapsed or refractory FL. It is anticipated that this drug will also be approved for use as consolidation therapy after successful first-line treatment. Here we first will review the published literature supporting the use of (90)Y-ibritumomab tiuxetan in the aforementioned indications and emerging data showing applicability of ibritumomab tiuxetan as sole first-line therapy for FL, as well as in the transplant setting. Possible strategies of incorporating ibritumomab tiuxetan into the treatment algorithm of FL are discussed.

Treatment of follicular lymphoma: current status

With the recent proliferation of treatment options for patients with follicular lymphoma (FL), median survival has been shown to have improved, from 84 months between 1983 and 1989 to 93 months between 1993 and 1999. Nevertheless, relapse is common in this patient group, and treatment options that extend the duration of remission without increased toxicity are still required. Rituximab has made a major contribution to the treatment of patients with FL, improving outcomes and making new treatment schedules possible. It is now a standard practice to administer rituximab with first-line combination chemotherapy in patients with FL. In addition, a number of current trials are examining the potential role of rituximab maintenance therapy in improving outcomes in FL. However, at present it is not clear which schedules or combinations are the most effective, and further randomised controlled trials of treatment strategies incorporating rituximab are needed to provide the evidence that will allow clinicians to maximise the potential of this drug. Second-line options for the treatment of FL include allogeneic stem cell transplantation, radioimmunotherapy targeted to CD20 and, in selected patients, autologous stem cell transplantation. New treatment approaches for FL currently being investigated in the second-line setting include the proteasome inhibitor, bortezomib and novel anti-CD20 monoclonal antibodies.

A comparative analysis of conventional and pretargeted radioimmunotherapy of B-cell lymphomas by targeting CD20, CD22, and HLA-DR singly and in combinations

Relapsed B-cell lymphomas are currently incurable with conventional chemotherapy and radiation treatments. Radiolabeled antibodies directed against B-cell surface antigens have emerged as effective and safe therapies for relapsed lymphomas. We therefore investigated the potential utility of both directly radiolabeled 1F5 (anti-CD20), HD39 (anti-CD22), and Lym-1 (anti-DR) antibodies (Abs) and of pretargeted radioimmunotherapy (RIT) using Ab-streptavidin (SA) conjugates, followed by an N-acetylgalactosamine dendrimeric clearing agent and radiometal-labeled DOTA-biotin, for treatment of lymphomas in mouse models using Ramos, Raji, and FL-18 human lymphoma xenografts. This study demonstrates the marked superiority of pretargeted RIT for each of the antigenic targets with more complete tumor regressions and longer mouse survival compared with conventional one-step RIT. The Ab-SA conjugate yielding the best tumor regression and progression-free survival after pretargeted RIT varied depending upon the lymphoma cell line used, with 1F5 Ab-SA and Lym-1 Ab-SA conjugates yielding the most promising results overall. Contrary to expectations, the best rates of mouse survival were obtained using optimal single Ab-SA conjugates rather than combinations of conjugates targeting different antigens. We hypothesize that clinical implementation of pretargeted RIT methods will provide a meaningful prolongation of survival for patients with relapsed lymphomas compared with currently available treatment strategies.

Follicular lymphoma: clinical features and treatment

Follicular lymphoma (FL) is the second most common subtype of non-Hodgkin's lymphoma (NHL) in the Western world, constituting up to 22% of the total cases of NHL. This article describes the clinical characteristics of FL, its prognostic indicators, and its clinical course, including transformation to an aggressive lymphoma. Primary management and therapies for recurrent FL are detailed.

Phase II trial of short-course CHOP-R followed by 90Y-ibritumomab tiuxetan and extended rituximab in previously untreated follicular lymphoma

PURPOSE

Radioimmunotherapy has been approved for relapsed follicular lymphoma (FL), including rituximab-refractory FL. This study was designed to determine the CR rate with short-course chemoimmunotherapy with cyclophosphamide, doxorubicin, vincristine, prednisone, and rituximab (CHOP-R) followed by 90-Y ibritumomab tiuxetan (RIT) with extended rituximab as first-line treatment.

EXPERIMENTAL DESIGN

Between March 2004 and February 2007, 60 patients with stage II to IV symptomatic or bulky FL from a single institution supported by a large community network entered this phase II trial. Patients received CHOP-R for three treatment cycles before RIT followed by four additional weekly treatments with rituximab. Response was determined using fusion [(18) F] fluorodeoxyglucose-positron emission tomography (PET)-computed tomography (CT) imaging.

RESULTS

Of the 60 patients entering this trial, 55 patients completed all protocol therapy. The median follow up was 19.7 months (range, 0.26-35.9 months). For intent-to-treat analysis, the complete response (CR) rate after CHOP-R, as assessed by CT and PET imaging, was 40% and 46%, respectively. After RIT, the CR rate improved, as assessed by CT and PET imaging, to 82% and 89%, respectively. Ten patients have progressed, including eight from best response of CR. Seven of 18 patients who were PET positive after CHOP-R progressed compared with 3 of 37 patients who were PET negative (P=0.010).

CONCLUSIONS

In patients with previously untreated, symptomatic or bulky FL, short-course chemoimmunotherapy and consolidation RIT and extended rituximab resulted in a high CR rate. Failure to achieve an early PET CR after CHOP-R indicated high risk of relapse.