Efficacy and safety of tositumomab and iodine-131 tositumomab (Bexxar) in B-cell lymphoma, progressive after rituximab

In vivo-stable bis-iminobiotin for targeted radionuclide delivery with the mutant streptavidin

Targeted delivery of radionuclides to tumors is significant in theranostics applications for precision medicine. Pre-targeting, in which a tumor-targeting vehicle and a radionuclide-loaded effector small molecule are administered separately, holds promise since it can reduce unnecessary internal radiation exposure of healthy cells and can minimize radiation decay. The success of the pre-targeting delivery requires an in vivo-stable tumor-targeting vehicle selectively binding to tumor antigens and an in vivo-stable small molecule effector selectively binding to the vehicle accumulated on the tumor. We previously reported a drug delivery system composed of a low-immunogenic streptavidin with weakened affinity to endogenous biotin and a bis-iminobiotin with high affinity to the engineered streptavidin. It was, however, unknown whether the bis-iminobiotin is stable in vivo when administered alone for the pre-targeting applications. Here we report a new in vivo-stable bis-iminobiotin derivative. The keys to success were the identification of the degradation site of the original bis-iminobiotin treated with mouse plasma and the structural modification of the degradation site. We disclosed the successful pre-targeting delivery of astatine-211 (211At), α-particle emitter, to the CEACAM5-positive tumor in xenograft mouse models.

Approaches to Reducing Normal Tissue Radiation from Radiolabeled Antibodies

Radiolabeled antibodies are powerful tools for both imaging and therapy in the field of nuclear medicine. Radiolabeling methods that do not release radionuclides from parent antibodies are essential for radiolabeling antibodies, and practical radiolabeling protocols that provide high in vivo stability have been established for many radionuclides, with a few exceptions. However, several limitations remain, including undesirable side effects on the biodistribution profiles of antibodies. This review summarizes the numerous efforts made to tackle this problem and the recent advances, mainly in preclinical studies. These include pretargeting approaches, engineered antibody fragments and constructs, the secondary injection of clearing agents, and the insertion of metabolizable linkages. Finally, we discuss the potential of these approaches and their prospects for further clinical application.

Theranostics in Hematooncology

In the early 2000s, major clinical trials provided evidence of a favorable outcome from antibody-mediated radioimmunotherapy for hematologic neoplasms, which then led to Food and Drug Administration approval. For instance, the theranostic armamentarium for the referring hematooncologist now includes ⁹⁰Y-ibritumomab tiuxetan for refractory low-grade follicular lymphoma or transformed B-cell non-Hodgkin lymphoma, as well as ¹³¹I-tositumomab for rituximab-refractory follicular lymphoma. Moreover, the first interim results of the SIERRA phase III trial reported beneficial effects from the use of ¹³¹I-anti-CD45 antibodies (Iomab-B) in refractory or relapsed acute myeloid leukemia. During the last decade, the concept of theranostics in hematooncology has been further expanded by C-X-C motif chemokine receptor 4-directed molecular imaging. Beyond improved detection rates of putative sites of disease, C-X-C motif chemokine receptor 4-directed PET/CT also selects candidates for radioligand therapy using β-emitting radioisotopes targeting the identical chemokine receptor on the lymphoma cell surface. Such image-piloted therapeutic strategies provided robust antilymphoma efficacy, along with desired eradication of the bone marrow niche, such as in patients with T- or B-cell lymphoma. As an integral part of the treatment plan, such radioligand therapy-mediated myeloablation also allows one to line up patients for stem cell transplantation, which leads to successful engraftment during the further treatment course. In this continuing education article, we provide an overview of the current advent of theranostics in hematooncology and highlight emerging clinical applications.

Incidence of second primary malignancies in relapsed/refractory B-cell non-Hodgkin's lymphoma patients in England

BACKGROUND

Treatments for relapsed/refractory (r/r) B-cell non-Hodgkin's lymphoma (NHL) may be associated with an increased risk of second primary malignancies (SPMs). Currently available SPM incidence benchmarks are unreliable due to small sample sizes.

METHODS

The Cancer Analysis System (CAS), a population-level cancer database in England, was used to identify patients with incident B-cell NHL diagnosed during 2013-2018 with evidence of r/r disease. Incidence rates (IRs) of SPMs after r/r disease diagnosis were calculated per 1000 person-years (PYs) and stratified by age, sex, and SPM type.

RESULTS

We identified 9444 patients with r/r B-cell NHL disease. Of those who were eligible for SPM analysis, nearly 6.0% (470/7807) developed at least one SPM after r/r disease diagnosis (IR: 44.7; 95% confidence interval [CI]: 40.9-48.9). Of note, 205 (2.6%) had a non-melanoma skin cancer (NMSC) SPM. IR of SPMs was the highest for patients with r/r chronic lymphocytic leukemia/small lymphocytic leukemia (80.0) and lowest for diffuse large B-cell lymphoma (DLBCL) (30.9). Patients with DLBCL had the shortest overall survival after r/r disease diagnosis.

CONCLUSIONS

This real-world data study suggests that the IR of SPM among patients with r/r B-cell NHL is 44.7 per 1000 PY and that most SPMs diagnosed after r/r disease diagnosis are NMSCs, establishing a basis for the comparison of safety outcomes for new treatments being developed for r/r B-cell NHL.

Use of imaging-based dosimetry for personalising radiopharmaceutical therapy of cancer

Theranostics - i.e., the combination of molecular imaging and radiopharmaceutical therapy of cancer targeting a common biological feature - is a rapidly expanding field owing the recent successes of novel radiopharmaceutical therapies, such as ¹⁷⁷Lu-based prostate-specific membrane antigen radioligand therapy of prostate cancer and peptide receptor radionuclide therapy of neuroendocrine tumours. Despite the ongoing technical developments in imaging-based dosimetry, the existence of tumour absorbed dose-efficacy and organ absorbed dose-toxicity relationships, as well as the high interpatient variability in absorbed doses per unit activity, radiopharmaceutical therapies are still mostly administered in a fixed-activity, one-size-fits-all fashion. This is at odds with the principles of radiation oncology, where the absorbed doses to tissues are prescribed and their delivery is carefully planned and controlled for each individual patient to maximise the clinical benefits. There is a growing body of clinical evidence that dosimetry-based radiopharmaceutical therapy allows to safely optimise tumour irradiation, which translates into improved clinical outcomes. In this narrative review, we will present the reported prospective clinical experience to date on the use of imaging-based dosimetry to personalise radiopharmaceutical therapies.

Immuno-PET Imaging and Radioimmunotherapy of Lymphomas

Monoclonal antibodies (Ab) have revolutionized the management of lymphomas, the most common hematologic malignancy in adults. Indeed, incorporation of rituximab into the regimen for indolent non-Hodgkin's lymphomas (NHLs) has dramatically improved treatment response and disease outcome. Yet, newer Ab therapeutics against promising antigen targets need to be developed to treat refractory or relapsed patients. Treatment efficacy can be further enhanced by conjugating toxic molecules to the Abs. Radioimmunotherapy (RIT) harnesses Abs as vehicles for targeted delivery of therapeutic radionuclide payloads for direct killing of targeted tumor cells. Positron emission tomography (PET) with radiolabeled Abs (called immuno-PET) can facilitate the development of new Ab therapeutics and RIT by providing pharmacokinetic and pharmacodynamic information and by quantifying tumor antigen level relevant for treatment decision. Immuno-PET has recently gravitated toward labeling Abs with ⁸⁹Zr, a radiometal with a 3.3 day half-life that is trapped following Ab internalization and thus provides high-resolution PET images with excellent contrast. Immuno-PET methods against major lymphoma antigens including CD20 and other promising targets are currently under development. With continued improvements, immuno-PET has the potential to be used in lymphoma management as an imaging biomarker for patient selection and assessment of treatment response.

Individualization of Radionuclide Therapies: Challenges and Prospects

Simple Summary

Currently, patient-specific treatment plans and dosimetry calculations are not routinely performed for radionuclide therapies. In external beam radiotherapy, it is quite the opposite. As a result, a small fraction of patients receives optimal radioactivity. This conservative approach provides “radiation safety” to healthy tissues but delivers a lower than indicated absorbed dose to the tumors, resulting in a lower response rate and a higher disease relapse rate. Evidence shows that better and more predictable outcomes can be achieved with patient-individualized dose assessment. Therefore, the incorporation of individual planning into radionuclide therapies is a high priority for nuclear medicine physicians and medical physicists alike. Internal dosimetry is used in tumor therapy to optimize the absorbed dose to the target tissue. The main reasons for the difficulties in incorporating patients’ internal dosimetry into routine clinical practice are discussed. The article presents the prospects for the routine implementation of personalized radionuclide therapies.

Abstract

The article presents the problems of clinical implementation of personalized radioisotope therapy. The use of radioactive drugs in the treatment of malignant and benign diseases is rapidly expanding. Currently, in the majority of nuclear medicine departments worldwide, patients receive standard activities of therapeutic radiopharmaceuticals. Intensively conducted clinical trials constantly provide more evidence of a close relationship between the dose of radiopharmaceutical absorbed in pathological tissues and the therapeutic effect of radioisotope therapy. Due to the lack of individual internal dosimetry (based on the quantitative analysis of a series of diagnostic images) before or during the treatment, only a small fraction of patients receives optimal radioactivity. The vast majority of patients receive too-low doses of ionizing radiation to the target tissues. This conservative approach provides “radiation safety” to healthy tissues, but also delivers lower radiopharmaceutical activity to the neoplastic tissue, resulting in a low level of response and a higher relapse rate. The article presents information on the currently used radionuclides in individual radioisotope therapies and on radionuclides newly introduced to the therapeutic market. It discusses the causes of difficulties with the implementation of individualized radioisotope therapies as well as possible changes in the current clinical situation.

Evolving role of biomaterials in diagnostic and therapeutic radiation oncology

Radiation therapy to treat cancer has evolved significantly since the discovery of x-rays. Yet, radiation therapy still has room for improvement in reducing side effects and improving control of cancer. Safer and more effective delivery of radiation has led us to novel techniques and use of biomaterials. Biomaterials in combination with radiation and chemotherapy have started to appear in pre-clinical explorations and clinical applications, with many more on the horizon. Biomaterials have revolutionized the field of diagnostic imaging, and now are being cultivated into the field of theranostics, combination therapy, and tissue protection. This review summarizes recent development of biomaterials in radiation therapy in several application areas.

Phase I Study of Yttrium-90 Radiolabeled M5A Anti-Carcinoembryonic Antigen Humanized Antibody in Patients with Advanced Carcinoembryonic Antigen Producing Malignancies

Background: M5A is a humanized monoclonal antibody (mAb) directed against carcinoembryonic antigen (CEA) The purpose of this first in human phase I dose-escalation trial was to characterize the toxicities and determine the maximum tolerated dose (MTD) of yttrium-90 (90Y)-DOTA-M5A as a single agent and in combination with gemcitabine (gem). Methods: Patients with advanced metastatic CEA-producing malignancies who had progressed on standard therapies were first administered indium-111 (111In)-DOTA-M5A. If tumor targeting was observed, the patient then received the therapy dose of 90Y-DOTA-M5A. Serial scans, blood sampling, and 24 h urine collections were then performed to estimate radiation doses to organs and total body. Assays for human antihuman antibody (HAHA) responses were performed out to 6 months. Results: Of the 18 patients who received 111In-DOTA-M5A, 16 received 90Y-DOTA-M5A therapy; 1 patient at 14 mCi/m2 with gem (150 mg/m2 days 1and 3), 3 patients at 12 mCi/m2 with gem, 6 patients at 12 mCi/m2 without gem, and 6 at 10 mCi/m2 without gem. Prolonged cytopenias resulted in discontinuation of dose escalation with gemcitabine. A single agent MTD of 10 mCi/m2 was established based on dose-limiting hematopoietic toxicities. HAHA immune response was identified in 2 of 16 patients (12.5%). Stable disease at 3 months was seen in 10 patients and 2 patients demonstrated an 88% and 64% decrease in CEA back to normal levels. In 2 patients 111In-DOTA-M5A imaging revealed previously unknown brain metastases. Conclusion: This study demonstrates the potential utility of the 90Y-DOTA-M5A anti-CEA mAb as a therapeutic antibody. There is decreased immunogenicity compared with murine and chimeric mAbs, allowing for the potential of multiple administrations. Combined modality therapy approaches incorporating this agent should continue to be evaluated.

Current Development of Monoclonal Antibodies in Cancer Therapy

Exploiting the unique specificity of monoclonal antibodies has revolutionized the treatment and diagnosis of haematological and solid organ malignancies; bringing benefit to millions of patients over the past decades. Recent achievements include conjugating antibodies with toxic payloads resulting in superior efficacy and/or reduced toxicity, development of molecular imaging techniques targeting specific antigens for use as predictive and prognostic biomarkers, the development of novel bi- and tri-specific antibodies to enhance therapeutic benefit and abrogate resistance and the success of immunotherapy agents. In this chapter, we review an overview of antibody structure and function relevant to cancer therapy and provide an overview of pivotal clinical trials which have led to regulatory approval of monoclonal antibodies in cancer treatment. We further discuss resistance mechanisms and the unique side effects of each class of antibody and provide an overview of emerging therapeutic agents.

Novel Methods to Improve the Efficiency of Radioimmunotherapy for Non-Hodgkin Lymphoma

Radioimmunotherapy (RIT) is a novel strategy for treating non-Hodgkin lymphoma (NHL). Several studies have shown the promising results of using RIT in NHL, which have led to FDA approval for two RIT agents in treating low grade NHL. In spite of these favorable results in low-grade NHL, most of the aggressive or relapsed/refractory NHL subjects experience relapses following RIT. Although more aggressive treatments such as myeloablative doses of RIT followed by stem cell transplantation appear to be able to provide a longer survival for some patients these approaches are associated with significant treatment-related adverse events and challenging to deliver in most centers. Therefore, it seems reasonable to develop treatment approaches that enhance the efficiency of RIT, while reducing its toxicity. In this paper, novel methods that improve the efficiency of RIT and reduce its toxicity through various mechanisms are reviewed. Further clinical development of these methods could expand the NHL patient groups eligible for receiving RIT, and even extend the use of RIT to new indications and disease groups in future.

90Y-NM600 targeted radionuclide therapy induces immunologic memory in syngeneic models of T-cell Non-Hodgkin's Lymphoma

Finding improved therapeutic strategies against T-cell Non-Hodgkin’s Lymphoma (NHL) remains an unmet clinical need. We implemented a theranostic approach employing a tumor-targeting alkylphosphocholine (NM600) radiolabeled with ⁸⁶Y for positron emission tomography (PET) imaging and ⁹⁰Y for targeted radionuclide therapy (TRT) of T-cell NHL. PET imaging and biodistribution performed in mouse models of T-cell NHL showed in vivo selective tumor uptake and retention of ⁸⁶Y-NM600. An initial toxicity assessment examining complete blood counts, blood chemistry, and histopathology of major organs established ⁹⁰Y-NM600 safety. Mice bearing T-cell NHL tumors treated with ⁹⁰Y-NM600 experienced tumor growth inhibition, extended survival, and a high degree of cure with immune memory toward tumor reestablishment. ⁹⁰Y-NM600 treatment was also effective against disseminated tumors, improving survival and cure rates. Finally, we observed a key role for the adaptive immune system in potentiating a durable anti-tumor response to TRT, especially in the presence of microscopic disease.

Hernandez et al. show the effectiveness of ⁹⁰Y for targeted radionucleotide therapy of T-cell Non-Hodgkin’s Lymphoma (NHL). This study suggests that delivering radiation to all NHL disease sites elicits minimal toxicity and induces a memory T-cell response, inviting combination therapies with immune activating agents.

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.

Cost-Effectiveness of Obinutuzumab in Combination with Bendamustine Followed by Obinutuzumab Maintenance versus Bendamustine Alone in Treatment of Patients with Rituximab-Refractory Follicular Lymphoma in Norway

AIMS

To evaluate the cost-effectiveness of obinutuzumab in combination with bendamustine followed by obinituzumab maintenance (Obin-Benda) compared to bendamustine alone (Benda) in patients with refractory follicular lymphoma (FL) in a Norwegian setting.

METHODS

A three-state area-under-the-curve (AUC) model was developed. The states included were progression-free-survival (PFS), progressed disease (PD), and death. Each state had costs and utilities assigned to it. The pivotal phase III randomized controlled trial GADOLIN was used for clinical input in the model along with Norwegian cost estimates. The trial demonstrated that Obin-Benda improved overall survival (OS), with a hazard ratio (HR) of 0.67 (95% CI 0.47-0.96), and reduced the likelihood of progression or death (HR 0.52, 95% CI 0.39-0.69) compared to Benda. The model used EQ-5D data collected in the GADOLIN trial, with UK tariffs assigned to the EQ-5D scores.

RESULTS

The total quality adjusted life-years (QALYs) for the patients on Obin-Benda were estimated to be 4.67, compared to 3.65 for Benda, while the total costs were estimated to be €98,849 and €51,570, respectively. Obin-Benda had an incremental gain of 1.02 QALYs compared to Benda, at an additional cost of €47,279. The estimated deterministic incremental cost-effectiveness ratio (ICER) was €46,438 per QALY gained, while the probabilistic ICER was €46,887 per QALY gained (95% CI €34,772-€59,443). The results were robust to changes in various sensitivity and scenario analyses.

CONCLUSIONS

The cost-effectiveness threshold in Norway is not public, but based on previous decisions it is estimated to be up to approximately €89,000 per QALY (NOK 800,000). The results of the analysis indicate that obinutuzumab in combination with bendamustine followed by obinutuzumab maintenance may be cost-effective compared to bendamustine alone in Norway.

Initial Experience with Tositumomab and I-131-Labeled Tositumomab for Treatment of Relapsed/Refractory Hodgkin Lymphoma

PURPOSE

To determine the maximum tolerated dose (MTD) of [¹³¹I]tositumomab in patients with refractory/recurrent Hodgkin lymphoma (HL) and to preliminarily determine if [¹³¹I]tositumomab has activity against HL and if positron emission tomography (PET) with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]DG) performed 6 weeks post-therapy predicted 12-week response.

PROCEDURES

Separate dose-finding studies were performed for patients with and without prior transplant. A single therapeutic total body radiation dose (TBD) of [¹³¹I]tositumomab was administered. TBD was escalated/de-escalated based on dose-limiting hematologic toxicity (DLT) using a modified continual reassessment method. [¹⁸F]DG-PET/CT scans were performed at baseline and 6 and 12 weeks post therapy.

RESULTS

Twelve patients (nine classical HL, three lymphocyte-predominant [LP] HL) completed two dosing levels (n = 3 each) in the post-transplant (55 cGy, 79 cGy) and no transplant (75 cGy, 87 cGy) groups. Hematologic toxicities were common and transient. Twelve weeks after [¹³¹I]tositumomab, 10 patients progressed and two with LPHL achieved complete response. [¹⁸F]DG-PET/CT at 6 weeks post therapy appeared more predictive than CT at 6 weeks of a response at 12 weeks.

CONCLUSIONS

Tositumomab and [¹³¹I]tositumomab was well-tolerated in patients with relapsed/refractory HL. Complete responses in LPHL support a therapeutic effect in this subtype. Early metabolic response assessments by [¹⁸F]DG-PET in HL after radioimmunotherapy appear to be more predictive than purely anatomic assessments.

Cardio-Oncology: Cancer Therapy-related Cardiovascular Complications in a Molecular Targeted Era: New Concepts and Perspectives

Cardio-oncology is a medical discipline that identifies, prevents, and treats the cardiovascular complications related to cancer therapy. Due to the remarkable proliferation of new cancer therapies causing cardiovascular complications, such as hypertension, heart failure, vascular complications, and cardiac arrhythmia, we provide an extensive, comprehensive revision of the most up-to-date scientific information available on the cardiovascular complications associated with the use of newer, novel chemotherapeutic agents, including their reported incidence, suggested pathophysiology, clinical manifestations, potential treatment, and prevention. The authors consider this topic to be relevant for the clinicians since cardiovascular complications associated with the administration of recently approved drugs are relatively underappreciated. The purpose of this article is to provide a state-of-the-art review of cardiovascular complications associated with the use of newer, novel chemotherapeutic agents and targeted therapies, including their reported incidence, suggested pathophysiology, clinical manifestations, potential treatment, and prevention.  Ongoing efforts are needed to provide a better understanding of the frequency, mechanisms of disease, prevention, and treatment of cardiovascular complications induced by the newer, novel chemotherapeutic agents. Development of a cardio-oncology discipline is warranted in order to promote task forces aimed at the creation of oncology patient-centered guidelines for the detection, prevention, and treatment of potential cardiovascular side effects associated with newer cancer therapies.

Induction of potent apoptosis by an anti-CD20 aptamer via the crosslink of membrane CD20 on non-Hodgkin's lymphoma cells

An anti-CD20 DNA aptamer was successfully generated by cell-SELEX, the crosslink of which can induce potent apoptosis in target cells.

The Role of Autologous and Allogeneic Stem Cell Transplantation in Follicular Lymphoma in The New Drugs Era

Follicular lymphoma (FL) is the second most common histotype of non-Hodgkin’s lymphoma, and it is generally characterized by a heterogeneous clinical course. Despite recent therapeutic and diagnostic improvements, a significant fraction of FL patients still relapsed. In younger and/or fit FL relapsed patients bone marrow transplant (BMT) has represented the main salvage therapy for many years. Thanks to the ability of high-dose chemotherapy to overcome the lymphoma resistance and refractoriness, autologous stem cell transplantation (ASCT) can achieve a high complete remission rate (CR) and favorable outcome regarding progression-free survival (PFS) and overall survival (OS). Allogeneic stem cell transplantation (alloSCT) combines the high dose chemotherapy effect together with the immune reaction of the donor immune system against lymphoma, the so-called ‘graft versus lymphoma’ (GVL) effect. Considering the generally higher transplant-related mortality (TRM), alloSCT is mostly indicated for FL relapsed after ASCT. During the last years, there have been a great spread of novel effective and feasible drugs Although these and future novel drugs will probably change our current approach to FL, the OS post-BMT (ASCT and alloSCT) has never been reproduced by any novel combination. In this scenario, it is important to correctly evaluate the disease status, the relapse risk and the comorbidity profile of the relapsed FL patients in order to provide the best salvage therapy and eventually transplant consolidation.

Targeted Cancer Therapy Using Radiolabeled Monoclonal Antibodies

Radioimmunotherapy (RIT) combines the advantages of targeted radiation therapy and specific immunotherapy using monoclonal antibodies. RIT can be used either to target tumor cells or to specifically suppress immunocompetent host cells in the setting of allogeneic transplantation. The choice of radionuclide used for RIT depends on its distinct radiation characteristics and the type of malignancy or cells targeted. Beta-emitters with their lower energy and longer path length are more suitable to target bulky, solid tumors whereas α-emitters with their high linear energy transfer and short path length are better suited to target hematopoietic cells (normal or malignant). Different approaches of RIT such as the use of stable radioimmunoconjugates or of pretargeting strategies are available. Encouraging results have been obtained with RIT in patients with hematologic malignancies. The results in solid tumors are somewhat less favorable but new strategies for patients with minimal residual disease using adjuvant and locoregional treatment are evolving. This report outlines basic principles of RIT, gives an overview of available radionuclides and radioimmunoconjugates, and discusses clinical results with special emphasis on their use in hematologic malignancies including use in conditioning regimens for bone marrow transplantation.

Obinutuzumab plus bendamustine versus bendamustine monotherapy in patients with rituximab-refractory indolent non-Hodgkin lymphoma (GADOLIN): a randomised, controlled, open-label, multicentre, phase 3 trial

BACKGROUND

Patients with indolent non-Hodgkin lymphoma who fail to achieve adequate disease control with rituximab-based treatment have few treatment options and a poor prognosis. We aimed to assess a combination of obinutuzumab (GA101), a novel glyco-engineered type II anti-CD20 monoclonal antibody, and bendamustine in this patient population.

METHODS

In this open-label, randomised, phase 3 study (GADOLIN), patients aged 18 years or older with histologically documented, CD20-positive indolent non-Hodgkin lymphoma refractory to rituximab were enrolled at 83 hospital and community sites in 14 countries in Europe, Asia, and North and Central America. Patients were randomly assigned (1:1) using a hierarchical dynamic randomisation scheme stratified by indolent non-Hodgkin lymphoma subtype, rituximab-refractory type, number of previous therapies, and geographical region, to receive induction treatment (six 28-day cycles) with obinutuzumab plus bendamustine or bendamustine monotherapy, both given intravenously. Obinutuzumab plus bendamustine dosing was obinutuzumab 1000 mg (days 1, 8, and 15, cycle 1; day 1, cycles 2-6) plus bendamustine 90 mg/m(2) per day (days 1 and 2, cycles 1-6), and bendamustine monotherapy dosing was 120 mg/m(2) per day (days 1 and 2, all cycles). Non-progressing patients in the obinutuzumab plus bendamustine group received obinutuzumab maintenance (1000 mg every 2 months) for up to 2 years. The primary endpoint was progression-free survival in all randomised patients, as assessed by an independent review committee. Safety was assessed in all patients who received any amount of obinutuzumab or bendamustine. This study is registered with ClinicalTrials.gov, number NCT01059630, and has stopped recruiting patients.

FINDINGS

Between April 15, 2010, and Sept 1, 2014, when the study was stopped after a pre-planned interim analysis, 396 patients were randomly assigned (194 to obinutuzumab plus bendamustine and 202 to bendamustine monotherapy). After a median follow-up time of 21·9 months (IQR 12·1-31·0) in the obinutuzumab plus bendamustine group and 20·3 months (9·5-29·7) in the bendamustine monotherapy group, progression-free survival was significantly longer with obinutuzumab plus bendamustine (median not reached [95% CI 22·5 months-not estimable]) than with bendamustine monotherapy (14·9 months [12·8-16·6]; hazard ratio 0·55 [95% CI 0·40-0·74]; p=0·0001). Grade 3-5 adverse events occurred in 132 (68%) of 194 patients in the obinutuzumab plus bendamustine group and in 123 (62%) of 198 patients in the bendamustine monotherapy group. The most frequent grade 3 or worse adverse events were neutropenia (64 [33%] in the obinutuzumab plus bendamustine group vs 52 [26%] in the bendamustine monotherapy group), thrombocytopenia (21 [11%] vs 32 [16%]), anaemia (15 [8%] vs 20 [10%]) and infusion-related reactions (21 [11%] vs 11 [6%]). Serious adverse events occurred in 74 patients (38%) in the obinutuzumab plus bendamustine group and in 65 patients (33%) in the bendamustine monotherapy group, and deaths due to adverse events occurred in 12 patients (6%) and 12 patients (6%), respectively. Three (25%) of 12 adverse event-related deaths in the obinutuzumab plus bendamustine group and five (42%) of 12 in the bendamustine monotherapy group were treatment related.

INTERPRETATION

Obinutuzumab plus bendamustine followed by obinutuzumab maintenance has improved efficacy over bendamustine monotherapy in rituximab-refractory patients with indolent non-Hodgkin lymphoma, with manageable toxicity, and is a new treatment option for patients who have relapsed after or are no longer responding to rituximab-based therapy.

FUNDING

F Hoffmann-La Roche Ltd.

Therapeutic radionuclides in nuclear medicine: current and future prospects

The potential use of radionuclides in therapy has been recognized for many decades. A number of radionuclides, such as iodine-131 ((131)I), phosphorous-32 ((32)P), strontium-90 ((90)Sr), and yttrium-90 ((90)Y), have been used successfully for the treatment of many benign and malignant disorders. Recently, the rapid growth of this branch of nuclear medicine has been stimulated by the introduction of a number of new radionuclides and radiopharmaceuticals for the treatment of metastatic bone pain and neuroendocrine and other malignant or non-malignant tumours. Today, the field of radionuclide therapy is enjoying an exciting phase and is poised for greater growth and development in the coming years. For example, in Asia, the high prevalence of thyroid and liver diseases has prompted many novel developments and clinical trials using targeted radionuclide therapy. This paper reviews the characteristics and clinical applications of the commonly available therapeutic radionuclides, as well as the problems and issues involved in translating novel radionuclides into clinical therapies.

Development of Novel Anti-Cd20 Monoclonal Antibodies and Modulation in Cd20 Levels on Cell Surface: Looking to Improve Immunotherapy Response

Rituximab has been revolutionized and validated CD20 targeting monoclonal antibody. Although, it is widely used for lymphoma therapy and many patients have been benefited. However significant numbers of patients are refractory or developed resistance to current therapies due to low level of CD20 expression and/or availability on cells surface. Thus development of novel anti-CD20 mAbs with great cell killing ability and enhance CD20 levels on cell surface can potentially exploit lymphoma therapy. In this scenario, we are summarizing the recently developed mAbs against CD20 and compounds that have ability to induce CD20 expression at significant level. We also are providing information regarding combination strategy for use of radiation and anti-CD20 mAbs in vitro. However, it will need to be determined by rigorous at pre-clinical and clinic testing. We hope this review will be beneficial for current research in the area of immunotherapy or radio-immunotherapy.

An open-label expanded-access trial of bendamustine in patients with rituximab-refractory indolent non-Hodgkin lymphoma or previously untreated chronic lymphocytic leukemia: BEND-ACT

BACKGROUND

Bendamustine is a bifunctional alkylating agent with unique properties that distinguish it from other agents in its class. Bendamustine is used as monotherapy or in combination with other agents to treat patients with non-Hodgkin lymphoma (nhl) and chronic lymphocytic leukemia (cll).

METHODS

The prospective interventional open-label bend-act trial evaluated bendamustine in patients with rituximab-refractory indolent nhl (inhl) and previously untreated cll. Study objectives were to assess the safety and tolerability of bendamustine monotherapy and to provide patients with access to bendamustine before Health Canada approval. The study aimed to enrol up to 100 patients. All patients with inhl received an intravenous dose of bendamustine 120 mg/m(2) over 60 minutes on days 1 and 2 for up to eight 21- or 28-day treatment cycles. All patients with cll received an intravenous dose of bendamustine 100 mg/m(2) over 30 minutes on days 1 and 2 for up to six 28-day treatment cycles.

RESULTS

Of 90 patients treated on study (16 with cll and 74 with inhl), 35 completed the study (4 with cll and 31 with inhl). The most common treatment-emergent adverse events (teaes) were nausea (70%), fatigue (57%), vomiting (40%), and diarrhea (33%)-mostly grades 1 and 2. Ondansetron was the most common supportive medication used in the patients (63.5% of those with inhl and 68.8% of those with cll). Neutropenia (32%), anemia (23%), and thrombocytopenia (21%) were the most frequent hematologic teaes, with neutropenia being the most common grade 3 or 4 teae leading to dose modification. Dose delays occurred in 28 patients (31.3%) because of grade 3 or 4 teaes, with a higher incidence of dose delays being observed in inhl patients on the 21-day treatment cycle than in those on the 28-day treatment cycle (50.0% vs. 24.1%). During the study, 33 patients (36.7%) experienced at least 1 serious adverse event, and 4 deaths were reported (all in patients with inhl).

CONCLUSIONS

The type and frequency of the teaes reported accorded with observations in earlier clinical trials and post-marketing experiences, thus confirming the acceptable and manageable safety profile of bendamustine.

Phosphorus-32, a clinically available drug, inhibits cancer growth by inducing DNA double-strand breakage

Radioisotopes that emit electrons (beta particles), such as radioiodine, can effectively kill target cells, including cancer cells. Aqueous ³²P[PO₄] is a pure beta-emitter that has been used for several decades to treat non-malignant human myeloproliferative diseases. ³²P[PO₄] was directly compared to a more powerful pure beta-emitter, the clinically important ⁹⁰Y isotope. In vitro, ³²P[PO₄] was more effective at killing cells than was the more powerful isotope ⁹⁰Y (P ≤ 0.001) and also caused substantially more double-stranded DNA breaks than did ⁹⁰Y. In vivo, a single low-dose intravenous dose of aqueous elemental ³²P significantly inhibited tumor growth in the syngeneic murine cancer model (P ≤ 0.001). This effect is exerted by direct incorporation into nascent DNA chains, resulting in double-stranded breakage, a unique mechanism not duplicatable by other, more powerful electron-emitting radioisotopes. ³²P[PO₄] should be considered for human clinical trials as a potential novel anti-cancer drug.

Radioimmunotherapy of human tumours

The eradication of cancer remains a vexing problem despite recent advances in our understanding of the molecular basis of neoplasia. One therapeutic approach that has demonstrated potential involves the selective targeting of radionuclides to cancer-associated cell surface antigens using monoclonal antibodies. Such radioimmunotherapy (RIT) permits the delivery of a high dose of therapeutic radiation to cancer cells, while minimizing the exposure of normal cells. Although this approach has been investigated for several decades, the cumulative advances in cancer biology, antibody engineering and radiochemistry in the past decade have markedly enhanced the ability of RIT to produce durable remissions of multiple cancer types.

Nanomedicine in cancer therapy: challenges, opportunities, and clinical applications

Cancer is a leading cause of death worldwide. Currently available therapies are inadequate and spur demand for improved technologies. Rapid growth in nanotechnology towards the development of nanomedicine products holds great promise to improve therapeutic strategies against cancer. Nanomedicine products represent an opportunity to achieve sophisticated targeting strategies and multi-functionality. They can improve the pharmacokinetic and pharmacodynamic profiles of conventional therapeutics and may thus optimize the efficacy of existing anti-cancer compounds. In this review, we discuss state-of-the-art nanoparticles and targeted systems that have been investigated in clinical studies. We emphasize the challenges faced in using nanomedicine products and translating them from a preclinical level to the clinical setting. Additionally, we cover aspects of nanocarrier engineering that may open up new opportunities for nanomedicine products in the clinic.

Autologous transplant for relapsed follicular lymphoma: impact of pre-transplant rituximab sensitivity

Patients with rituximab-refractory follicular lymphoma (FL) have limited options. Before the rituximab era, autologous stem cell transplant (ASCT) was shown to improve outcomes in chemotherapy-sensitive, relapsed FL, but the impact of rituximab-sensitivity on these results is unknown. We analyzed 194 consecutive relapsed patients with FL who underwent ASCT at out center and categorized them as rituximab-sensitive (RS, n = 35), rituximab-refractory (RR, n = 65) or no rituximab (NoR, n = 94) if transplanted before rituximab was used. Progression-free survival at 3 years was 85% in RS and 35% in RR patients (p = 0.0004). Only rituximab-sensitivity was significant on multivariate analysis with improved overall survival (OS) (hazard ratio [HR] 0.24, p = 0.01) and progression-free survival (PFS) (HR 0.35, p = 0.006) in RS patients and increased relapse in RR patients (HR 2.11, p = 0.01). Pre-transplant rituximab-sensitivity is a strong independent predictor of post-transplant outcomes in relapsed FL, although one-third of RR patients achieved a PFS of over 3 years with ASCT.

The safety and treatment response of combination therapy of radioimmunotherapy and radiofrequency ablation for solid tumor: a study in vivo

OBJECTION

To investigate the safety and treatment response of radioimmunotherapy (RIT) in combination with radiofrequency ablation (RFA) for the treatment of VX2 tumor on rabbit.

MATERIALS AND METHODS

A total of 36 rabbits bearing VX2 tumor on the thigh were randomly assigned into 3 groups (group I: 1-2 cm; group II: 2-3 cm; group III: 3-4 cm) and 4 subgroups (A: as control, just puncture the tumor using the RFA electrode without power output; B: RFA alone; C: 131I-chTNT intratumoral injection alone; D: RFA+131I-chTNT intratumoral injection 3 days later). The variation of blood assay, weight and survival among different groups and subgroups were used to assess the treatment safety. Ultrasound (US) was used to monitor and assess the tumor response after treatment.

RESULTS

According to the results of the weight and the blood assay among different groups, subgroups, and at two time points (one day before and the 16th day after treatment), no damages to the liver, kidney function and myelosuppression resulting from the treatment were found. No significant differences in survivals among the four subgroups (p = 0.087) were found. In addition, 131I-chTNT did not show significant inhibition effect on VX2 tumor progression according to US measurements.

CONCLUSION

131I-chTNT intratumoral injection alone or in combination with RFA is relatively safe for rabbit without significant toxicity and shows no significant effect on the survival. The treatment response is not as satisfactory as anticipated.

Prolonged progression-free survival and preserved quality of life in the Canadian prospective study of tositumomab and iodine(131)-tositumomab for previously treated, rituximab-exposed, indolent non-Hodgkin lymphoma

Radioimmunotherapy offers a unique treatment modality for indolent non-Hodgkin lymphoma (iNHL). We report 5-year outcomes and quality of life (QoL) in tositumomab and iodine(131)-tositumomab (TST/I(131)-TST) treated patients with iNHL previously treated with rituximab. Ninety-three patients with ≥ 2 lines of therapy, responding to last treatment, were enrolled at 12 Canadian centers. Median age, disease duration and number of prior therapies (#PTx) were 59 years, 4.9 years and 5, respectively. Outcomes were response rate (43.0%), median progression-free survival (mPFS) (12.0 months), 5-year PFS (27%) and median overall survival (OS) (59.8 months). In responders, median response duration and mPFS were not reached. Improvements in QoL were seen by week 7. In univariate and multivariate analyses, hemoglobin, disease bulk and body surface area (BSA) predicted OS, whereas lactate dehydrogenase (LDH), bulk, BSA and #PTx predicted PFS. Most common adverse events (AEs) were fatigue and nausea. Two cases of myelodysplastic syndrome (MDS) were reported. TST/I(131)-TST was associated with durable responses, and prolonged OS and PFS in heavily pretreated iNHL.

Long term follow-up of BEAM-autologous and BEAM-alemtuzumab allogeneic stem cell transplantation in relapsed advanced stage follicular lymphoma

This is an analysis in 171 patients comparing BEAM-Auto and BEAM-Allo (alemtuzumab)-hematopoietic stem cell transplantation in relapsed follicular lymphoma. BEAM-Allo group had a lower 10 years cumulative incidence of relapse(31.4% vs 55.1%, p=0.042), a trend to a plateau in survival but no statistical differences in OS or DFS, and a TRM of 24%. When transplanted in CR BEAM-Allo patients had better OS and DFS. Incidence of acute and chronic GVHD was 16.6% and 22%. 29% of BEAM-Allo patients received DLI (all but two remain in CR and alive). Our data supports Allo-HSCT as a potential curative treatment for selected patients with FL.

PI3Kδ inhibition by idelalisib in patients with relapsed indolent lymphoma

BACKGROUND

Phosphatidylinositol-3-kinase delta (PI3Kδ) mediates B-cell receptor signaling and microenvironmental support signals that promote the growth and survival of malignant B lymphocytes. In a phase 1 study, idelalisib, an orally active selective PI3Kδ inhibitor, showed antitumor activity in patients with previously treated indolent non-Hodgkin's lymphomas.

METHODS

In this single-group, open-label, phase 2 study, 125 patients with indolent non-Hodgkin's lymphomas who had not had a response to rituximab and an alkylating agent or had had a relapse within 6 months after receipt of those therapies were administered idelalisib, 150 mg twice daily, until the disease progressed or the patient withdrew from the study. The primary end point was the overall rate of response; secondary end points included the duration of response, progression-free survival, and safety.

RESULTS

The median age of the patients was 64 years (range, 33 to 87); patients had received a median of four prior therapies (range, 2 to 12). Subtypes of indolent non-Hodgkin's lymphoma included follicular lymphoma (72 patients), small lymphocytic lymphoma (28), marginal-zone lymphoma (15), and lymphoplasmacytic lymphoma with or without Waldenström's macroglobulinemia (10). The response rate was 57% (71 of 125 patients), with 6% meeting the criteria for a complete response. The median time to a response was 1.9 months, the median duration of response was 12.5 months, and the median progression-free survival was 11 months. Similar response rates were observed across all subtypes of indolent non-Hodgkin's lymphoma, though the numbers were small for some categories. The most common adverse events of grade 3 or higher were neutropenia (in 27% of the patients), elevations in aminotransferase levels (in 13%), diarrhea (in 13%), and pneumonia (in 7%).

CONCLUSIONS

In this single-group study, idelalisib showed antitumor activity with an acceptable safety profile in patients with indolent non-Hodgkin's lymphoma who had received extensive prior treatment. (Funded by Gilead Sciences and others; ClinicalTrials.gov number, NCT01282424.).

Toxicity of targeted therapeutic agents in lymphoma and management: part 1: monoclonal antibodies and radioimmunotherapy

SUMMARY This two-part review strives to comprehensively characterize common toxicities associated with targeted therapies in lymphoma and their management. Current targeted therapies for lymphoma include monoclonal antibodies, radioimmunotherapy and histone deacteylase inhibitors. New drugs that are expected to significantly alter the therapeutic landscape include PI3K, Bruton’s tyrosine kinase and BCL2 inhibitors. This manuscript focuses on the toxicities and associated management recommendations of monoclonal antibodies and radioimmunotherapy. In the second part of this review, we will focus on the toxicities and management pertaining to targeted therapeutic agents including histone deacteylase, PI3K/AKT and Bruton’s tyrosine kinase and BCL2 inhibitors.

Treatment challenges in the management of relapsed or refractory non-Hodgkin's lymphoma - novel and emerging therapies

Over the last few decades, advances in immunochemotherapy have led to dramatic improvement in the prognosis of non-Hodgkin's lymphoma (NHL). Despite these advances, relapsed and refractory disease represents a major treatment challenge. For both aggressive and indolent subtypes of NHL, there is no standard of care for salvage regimens, with prognosis after relapse remaining relatively poor. Nevertheless, there are multiple emerging classes of targeted therapies for relapsed/refractory disease, including monoclonal antibodies, antibody- drug conjugates, radioimmunotherapy, small-molecule inhibitors of cell-growth pathways, and novel chemotherapy agents. This review will discuss treatment challenges of NHL, current available salvage regimens for relapsed/refractory NHL, and the safety and efficacy of novel emerging therapies.

What is the Role of the Bystander Response in Radionuclide Therapies?

Radionuclide therapy for cancer is undergoing a renaissance, with a wide range of radionuclide and clinical delivery systems currently under investigation. Dosimetry at the cellular and sub-cellular level is complex with inhomogeneity and incomplete targeting of all cells such that some tumor cells will receive little or no direct radiation energy. There is now sufficient preclinical evidence of a Bystander response which can modulate the biology of these un-irradiated cells with current research demonstrating both protective and inhibitory responses. Dependence upon fraction of irradiated cells has also been found and the presence of functional gap junctions appears to be import for several Bystander responses. The selection of either high or low LET radionuclides may be critical. While low LET radionuclides appear to have a Bystander response proportional to dose, the dose-response from high LET radionuclides are more complex. In media transfer experiments a “U” shaped response curve has been demonstrated for high LET treatments. However this “U” shaped response has not been seen with co-culture experiments and its relevance remains uncertain. For high LET treatments there is a suggestion that dose rate effects may also be important with inhibitory effects noted with 125I labelling study and a stimulatory seen with 123I labelling in one study.

Radioimmunotherapy of B-Cell Non-Hodgkin's Lymphoma

This manuscript reviews current advances in the use of radioimmunotherapy (RIT) for the treatment of B-cell non-Hodgkin's lymphoma (NHL). RIT has been in use for more than 20 years and has progressed significantly with the discovery of new molecular targets, the development of new stable chelates, the humanization of monoclonal antibodies (MAbs), and the use of pretargeting techniques. Today, two products targeting the CD20 antigen are approved: (131)I-tositumomab (Bexxar(®)), and (90)Y-ibritumomab tiuxetan (Zevalin(®)). (131)I-tositumomab is available in the United States, and (90)Y-ibritumumab tiuxetan in Europe, the United States, Asia, and Africa. RIT can be integrated in clinical practice using non-ablative activities for treatment of patients with relapsed or refractory follicular lymphoma (FL) or as consolidation after induction chemotherapy in front-line treatment in FL patients. Despite the lack of phase III studies to clearly define the efficacy of RIT in the management of B lymphoma in the era of rituximab-based therapy, RIT efficacy in NHL has been demonstrated. In relapsing refractory FL and transformed NHL, RIT as a monotherapy induces around 30% complete response with a possibility of durable remissions. RIT consolidation after induction therapy significantly improves the quality of the response. Dose-limiting toxicity of RIT is hematological, depending on bone marrow involvement and prior treatment. Non-hematological toxicity is generally low. Different studies have been published assessing innovative protocols of RIT or new indications, in particular treatment in patients with aggressive lymphomas. High-dose treatment, RIT as consolidation after different therapeutic induction modalities, RIT in first-line treatment or fractionated RIT showed promising results. New MAbs, in particular humanized MAbs, or combinations of naked and radiolabeled MAbs, also appear promising. Personalized dosimetry protocols should be developed to determine injected activity.

A phase I trial of immunostimulatory CpG 7909 oligodeoxynucleotide and 90 yttrium ibritumomab tiuxetan radioimmunotherapy for relapsed B-cell non-Hodgkin lymphoma

Radioimmunotherapy (RIT) for relapsed indolent non-Hodgkin lymphoma produces overall response rates (ORR) of 80% with mostly partial remissions. Synthetic CpG oligonucleotides change the phenotype of malignant B-cells, are immunostimulatory, and can produce responses when injected intratumorally and combined with conventional radiation. In this phase I trial, we tested systemic administration of both CpG and RIT. Eligible patients had biopsy-proven previously treated CD20+ B-cell NHL and met criteria for RIT. Patients received rituximab 250 mg/m(2) days 1,8, and 15; (111) In-ibritumomab tiuxetan days 1, 8; CpG 7909 days 6, 13, 20, 27; and 0.4 mCi/kg of (90) Y-ibritumomab tiuxetan day 15. The doses of CpG 7909 tested were 0.08, 0.16, 0.32 (six patients each) and 0.48 mg/kg (12 patients) IV over 2 hr without dose limiting toxicity. The ORR was 93% (28/30) with 63% (19/30) complete remission (CR); median progression free survival of 42.7 months (95% CI 18-NR); and median duration of response (DR) of 35 months (4.6-76+). Correlative studies demonstrated a decrease in IL10 and TNFα, and an increase in IL1β, in response to therapy. CpG 7909 at a dose of 0.48 mg/kg is safe with standard RIT and produces a high CR rate and long DR; these results warrant confirmation.

The outcome of reduced intensity allogeneic stem cell transplantation and autologous stem cell transplantation when performed as a first transplant strategy in relapsed follicular lymphoma: an analysis from the Lymphoma Working Party of the EBMT

Both auto-SCT and reduced intensity allo-SCT (RIST) are employed in the treatment of relapsed follicular lymphoma (FL). We have analysed the outcome of these two transplant procedures when used as a first transplant in this setting. We conducted a retrospective comparison of 726 patients who underwent an auto-SCT and 149 who underwent a RIST as a first transplant procedure for relapsed FL as reported to the Lymphoma Working Party of the European Bone Marrow Transplant. The non-relapse mortality (NRM) was significantly worse for patients undergoing a RIST (relative risk (RR) 4.0, P<0.001). The 1-year NRM was 15% for those undergoing a RIST compared with 3% for those undergoing an auto-SCT. Disease relapse or progression were significantly worse for those receiving an auto-SCT (RR 3.1, P<0.001). Patients undergoing a RIST had a 5-year relapse rate of 20% compared with 47% for those undergoing an auto-SCT. The PFS at 5 years was 57% for patients receiving a RIST compared with 48% for those receiving an auto-SCT. There was no significant difference in OS between the two groups. RIST is associated with a higher NRM and lower relapse rate in patients with relapsed FL.

Managing lymphoma with non-FDG radiotracers: current clinical and preclinical applications

Nuclear medicine imaging modalities such as positron emission tomography (PET) and single-photon emission computed tomography (SPECT) have played a prominent role in lymphoma management. PET with [(18)F]Fluoro-2-deoxy-D-glucose (FDG) is the most commonly used tool for lymphoma imaging. However, FDG-PET has several limitations that give the false positive or false negative diagnosis of lymphoma. Therefore, development of new radiotracers with higher sensitivity, specificity, and different uptake mechanism is in great demand in the management of lymphoma. This paper reviews non-FDG radiopharmaceuticals that have been applied for PET and SPECT imaging in patients with different types of lymphoma, with attention to diagnosis, staging, therapy response assessment, and surveillance for disease relapse. In addition, we introduce three radiolabeled anti-CD20 antibodies for radioimmunotherapy, which is another important arm for lymphoma treatment and management. Finally, the relatively promising radiotracers that are currently under preclinical development are also discussed in this paper.

Diffuse large B-cell lymphoma

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoid malignancy in adults accounting for 31% of all NHL in Western Countries. Following, morphological, biological and clinical studies have allowed the subdivision of DLBCLs into morphological variants, molecular and immunophenotypic subgroups and distinct disease entities. However, a large number of cases still remain biologically and clinically heterogeneous, for which there are no clear and accepted criteria for subclassification; these are collectively termed DLBCL, not otherwise specified (NOS). DLBCL-NOS occurs in adult patients, with a median age in the seventh decade, but the age range is broad, and it may also occur in children. Clinical presentation, behaviour and prognosis are variable, depending mainly of the extranodal site when they arise. These malignancies present in localized manner in approximately 20% of patients. Disseminated extranodal disease is less frequent, and one third of patients have systemic symptoms. Overall, DLBCLs are aggressive but potentially curable malignancies. Cure rate is particularly high in patients with limited disease with a 5-year PFS ranging from 80% to 85%; patients with advanced disease have a 5-year PFS ≈ 50%. The International Prognostic Index (IPI) and age adjusted IPI (aaIPI) are the benchmarks of DLBCL prognosis. First-line treatment for patients with DLBCL is based on the individual IPI score and age, and three major subgroups should be considered: elderly patients (>60 years, aaIPI=0-3); young patients with low risk (<60 years, aaIPI=0-1); young patients with high risk (<60 years, aaIPI=2-3). The combination of the anti-CD20 monoclonal antibody rituximab and CHOP chemotherapy, every 14 or 21 days, is the standard treatment for DLBCL patients. Recent randomized trials suggest that high-dose chemotherapy supported by autologous stem cell transplant (HDC/ASCT) should not be used as upfront treatment for young high-risk patients outside prospective clinical trials. HDC/ASCT is actually recommended in young patients who did not achieve CR after first-line chemotherapy. Consolidation radiotherapy should be reserved to patients with bulky disease who did not achieve CR after immunochemotherapy. Patients with high IPI score, which indicates increased LDH serum level and the involvement of more than one extranodal site, and patients with involvement of certain extranodal sites (a.e., testes and orbit) should receive CNS prophylaxis as part of first-line treatment. HDC/ASCT should be considered the standard therapy for DLBCL patients with chemotherapy-sensitive relapse. Overall results in patients who cannot be managed with HDC/ASCT due to age or comorbidity are disappointing. New effective and less toxic chemotherapy drugs or biological agents are also worth considering for this specific and broad group of patients. Several novel agents are undergoing evaluation in DLBCL; among other, immunomodulating agents (lenalidomide), m-TOR inhibitors (temsirolimus and everolimus), proteasome inhibitors (bortezomib), histone deacetylase inhibitors (vorinostat), and anti-angiogenetic agents (bevacizumab) are being investigated in prospective trials.

Changing role of stem cell transplantation in follicular lymphoma

Patients with advanced follicular lymphoma (FL) have numerous treatment options, including observation, radiotherapy, single-agent or combination chemotherapy, mAbs, and radioimmunoconjugates. These therapies can extend progression-free survival but none can provide a cure. Allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curable therapy for FL, with the field shifting more toward the use of reduced-intensity conditioning regimens because of the lower associated nonrelapse mortality compared with myeloablative regimens. However, GVHD and infection are still problematic in the allo-HSCT population. Autologous HSCT (auto-HSCT) confers high response rates and prolongs progression-free survival in relapsed patients who are chemosensitive, and an increasing amount of data suggest that auto-HSCT may be curative if offered to relapsed patients who are not heavily pretreated. Auto-HSCT has no role as consolidation therapy for patients in first remission based on the results from 3 large randomized trials. Novel conditioning regimens with radioimmunoconjugates have been used in both auto-HSCT and allo-HSCT regimens and results have shown efficacy even in chemorefractory patients. Therefore, with the exception of patients in first remission, the optimal timing for HSCT remains controversial. However, the outcomes seen after auto-HSCT and allo-HSCT continue to improve, and HSCT represents a treatment modality that should be considered in all FL patients, especially while their disease remains chemoresponsive.