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

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.

Utility of Targeted Positron Emission Tomography Imaging to Predict Schwannoma Growth in a Murine Tumor Model

OBJECTIVE

To identify if targeted positron emission tomography (PET) imaging with radiolabeled antibodies can predict tumor growth rate and ultimate tumor size in a murine flank schwannoma model.

STUDY DESIGN

Animal research study.

METHODS

Rat schwannoma cells were cultured and implanted into 40 athymic nude mice. Once tumors reached 5 mm in diameter, 30 mice were injected with zirconium-89 labeled antibodies (HER2/Neu, vascular endothelial growth factor receptor 2 (VEGFR2), or IgG isotype). PET/CT was performed, and standardized uptake values (SUV) were recorded. Tumors were serially measured until mice were sacrificed per IACUC protocol. Statistical analysis was performed to measure correlations between SUV values, tumor size, and growth.

RESULTS

Mean tumor sizes in mm3 on Day 0 were 144 ± 162 for anti-HER2/Neu, 212 ± 247 for anti-VEGFR2, and 172 ± 204 for IgG isotype groups respectively. Mean growth rates in mm3 /day were 531 ± 250 for HER2, 584 ± 188 for VEGFR2, and 416 ± 163 for the IgG isotype group. For both initial tumor size and growth rates, there was no significant difference between groups. There were significant correlations between maximum tumor volume and both the SUV max in the HER2 group (p = 0.0218, R2  = 0.5020), and we observed significant correlations between growth rate, and SUV values (p = 0.0156, R2  = 0.5394). Respectively, in the anti-VEGFR2 group, there were no significant correlations.

CONCLUSION

In a murine schwannoma model, immunotargeted PET imaging with anti-HER2/Neu antibodies predicted tumor growth rate and final tumor size. Laryngoscope, 134:1372-1380, 2024.

Recent preclinical and clinical advances in radioimmunotherapy for non-Hodgkin's lymphoma

Radioimmunotherapy (RIT) is a therapy that combines a radioactive nucleotide with a monoclonal antibody (mAb). RIT enhances the therapeutic effect of mAb and reduces toxicity compared with conventional treatment. The purpose of this review is to summarize the current progress of RIT for treating non-Hodgkin's lymphoma (NHL) based on recent preclinical and clinical studies. The efficacy of RIT targeting the B-lymphocyte antigen cluster of differentiation 20 (CD20) has been demonstrated in clinical trials. Two radioimmunoconjugates targeting CD20, yttrium-90 (90Y)-ibritumomab-tiuxetan (Zevalin) and iodine-131 (131I)-tositumomab (Bexxar), have been approved in the USA Food and Drug Administration (FDA) for treating relapsed/refractory indolent or transformed NHL in 2002 and 2003, respectively. Although these two radioimmunoconjugates are effective and least toxic, they have not achieved popularity due to increasing access to novel therapies and the complexity of their delivery process. RIT is constantly evolving with the identification of novel targets and novel therapeutic strategies using newer radionuclides such as alpha-particle isotopes. Alpha-particles show very short path lengths and high linear energy transfer. These characteristics provide increased tumor cell-killing activities and reduced non-specific bystander responses on normal tissue. This review also discusses reviewed pre-targeted RIT (PRIT) and immuno-positron emission tomography (PET). PRIT potentially increases the dose of radionuclide delivered to tumors while toxicities to normal tissues are limited. Immuno-PET is a molecular imaging tracer that combines the high sensitivity of PET with the specific targeting capability of mAb. Immuno-PET strategies targeting CD20 and other antigens are currently being developed. The theragnostic approach by immuno-PET will be useful in monitoring the treatment response.

Radioimmunotherapy with 131 I-rituximab for patients with relapsed or refractory follicular or mantle cell lymphoma

AIM

This study aimed to evaluate the safety and efficacy of 131 I-rituximab in patients with relapsed or refractory follicular or mantle cell lymphoma.

METHODS

Twenty-four patients with relapsed or refractory follicular or mantle cell lymphoma were administered unlabeled rituximab (70 mg) immediately before receiving a therapeutic dose of 131 I-rituximab. Contrast-enhanced 18F-fluorodeoxyglucose positron emission tomography/computed tomography was used a month later to assess tumor response.

RESULTS

This study enrolled 24 patients between June 2012 and 2022. Depending on how they responded to radioimmunotherapy (RIT), 131 I-rituximab was administered one to five times. Of the 24 patients, 9 achieved complete response after RIT and 8 achieved partial response. The median progression-free and overall survival was 5.9 and 37.9 months, respectively. During the follow-up period of 64.2 months, three patients were diagnosed with a secondary malignancy. Among treatment-related adverse events, hematologic toxicities were common, and grade 3-4 thrombocytopenia and neutropenia were reported in 66.6% of cases.

CONCLUSION

131 I-rituximab has an effective and favorable safety profile in patients with relapsed or refractory follicular lymphoma and mantle cell lymphoma. This suggests that RIT may also be considered a treatment option for patients with relapsed or refractory follicular lymphoma and mantle cell lymphoma.

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.

Radioimmunotherapy of Non-Hodgkin B-cell Lymphoma: An update

Systemic radioimmunotherapy (RIT) is arguably the most effective and least toxic anticancer treatment for non-Hodgkin lymphoma (NHL). In treatment-naïve patients with indolent NHL, the efficacy of a single injection of RIT compares with that of multiple cycles of combination chemotherapy. However, 20 years following the approval of the first CD20-targeting radioimmunoconjugates ⁹⁰Y-Ibritumomab-tiuxetan (Zevalin) and ¹³¹I-tositumomab (Bexxar), the number of patients referred for RIT in western countries has dramatically decreased. Notwithstanding this, the development of RIT has continued. Therapeutic targets other than CD20 have been identified, new vector molecules have been produced allowing for faster delivery of RIT to the target, and innovative radionuclides with favorable physical characteristics such as alpha emitters have been more widely available. In this article, we reviewed the current status of RIT in NHL, with particular focus on recent clinical and preclinical developments.

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.

Current and upcoming radionuclide therapies in the direction of precision oncology: A narrative review

As new molecular tracers are identified to target specific receptors, tissue, and tumor types, opportunities arise for the development of both diagnostic tracers and their therapeutic counterparts, termed "theranostics." While diagnostic tracers utilize positron emitters or gamma-emitting radionuclides, their theranostic counterparts are typically bound to beta and alpha emitters, which can deliver specific and localized radiation to targets with minimal collateral damage to uninvolved surrounding structures. This is an exciting time in molecular imaging and therapy and a step towards personalized and precise medicine in which patients who were either without treatment options or not candidates for other therapies now have expanded options, with tangible data showing improved outcomes. This manuscript explores the current state of theranostics, providing background, treatment specifics, and toxicities, and discusses future potential trends.

Radiotheranostics in oncology: Making precision medicine possible

A quintessential setting for precision medicine, theranostics refers to a rapidly evolving field of medicine in which disease is diagnosed followed by treatment of disease-positive patients using tools for the therapy identical or similar to those used for the diagnosis. Against the backdrop of only-treat-when-visualized, the goal is a high therapeutic index with efficacy markedly surpassing toxicity. Oncology leads the way in theranostics innovation, where the approach has become possible with the identification of unique proteins and other factors selectively expressed in cancer versus healthy tissue, advances in imaging technology able to report these tissue factors, and major understanding of targeting chemicals and nanodevices together with methods to attach labels or warheads for imaging and therapy. Radiotheranostics-using radiopharmaceuticals-is becoming routine in patients with prostate cancer and neuroendocrine tumors who express the proteins PSMA (prostate-specific membrane antigen) and SSTR2 (somatostatin receptor 2), respectively, on their cancer. The palpable excitement in the field stems from the finding that a proportion of patients with large metastatic burden show complete and partial responses, and this outcome is catalyzing the search for more radiotheranostics approaches. Not every patient will benefit from radiotheranostics; but, for those who cross the target-detected line, the likelihood of response is very high.

Precision Medicine in Therapy of Non-solid Cancer

The development and approval of the tyrosine kinase inhibitor imatinib in 2001 has heralded the advance of directed therapy options. Today, an armamentarium of targeted therapeutics is available and enables the use of precision medicine in non-solid cancer. Precision medicine is guided by the detection of tumor-specific and targetable characteristics. These include pathogenic fusions and/or mutations, dependency on specific signaling pathways, and the expression of certain cell surface markers. Within the first part, we review approved targeted therapies for the compound classes of small molecule inhibitors, antibody-based therapies and cellular therapies. Particular consideration is given to the underlying pathobiology and the respective mechanism of action. The second part emphasizes on how biomarkers, whether they are of diagnostic, prognostic, or predictive relevance, are indispensable tools to guide therapy choice and management in precision medicine. Finally, the examples of acute myeloid leukemia, chronic lymphocytic leukemia, and chronic myeloid leukemia illustrate how integration of these biomarkers helps to tailor therapy.

A Primer on Radiopharmaceutical Therapy

The goal of this article is to serve as a primer for the United States-based radiation oncologist who may be interested in learning more about radiopharmaceutical therapy (RPT). Specifically, we define RPT, review the data behind its current and anticipated indications, and discuss important regulatory considerations for incorporating it into clinical practice. RPT represents an opportunity for radiation oncologists to leverage 2 key areas of expertise, namely therapeutic radiation therapy and oncology, and apply them in a distinct context in collaboration with nuclear medicine and medical oncology colleagues. Although not every radiation oncologist will incorporate RPT into their day-to-day practice, it is important to understand the role for this modality and how it can be appropriately used in select patients.

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.

Radiolabeled Antibodies for Cancer Imaging and Therapy

Simple Summary

Monoclonal antibodies (mAbs) have the ability to specifically target tumor-cell antigens. This unique property has led to their use in the delivery of radioisotopes to tumor sites (scintigraphic imaging and radioimmunotherapy (RIT)). The choice of the radionuclide depends on its unique physical properties and intended use. Using radiolabeled mAbs with imaging techniques provides critical data that are essential for predicting side effects and determining an optimal antibody dose and treatment schedule. While RIT has been successful in the management of hematological malignancies, the treatment of solid tumors remains challenging. Various strategies are being investigated to improve the efficacy of RIT in solid tumors.

Abstract

Radioimmunoconjugates consist of a monoclonal antibody (mAb) linked to a radionuclide. Radioimmunoconjugates as theranostics tools have been in development with success, particularly in hematological malignancies, leading to approval by the US Food and Drug Administration (FDA) for the treatment of non-Hodgkin’s lymphoma. Radioimmunotherapy (RIT) allows for reduced toxicity compared to conventional radiation therapy and enhances the efficacy of mAbs. In addition, using radiolabeled mAbs with imaging methods provides critical information on the pharmacokinetics and pharmacodynamics of therapeutic agents with direct relevance to the optimization of the dose and dosing schedule, real-time antigen quantitation, antigen heterogeneity, and dynamic antigen changes. All of these parameters are critical in predicting treatment responses and identifying patients who are most likely to benefit from treatment. Historically, RITs have been less effective in solid tumors; however, several strategies are being investigated to improve their therapeutic index, including targeting patients with minimal disease burden; using pre-targeting strategies, newer radionuclides, and improved labeling techniques; and using combined modalities and locoregional application. This review provides an overview of the radiolabeled intact antibodies currently in clinical use and those in development.

Dosimetric Approaches for Radioimmunotherapy of Non-Hodgkin Lymphoma in Myeloablative Setting

Radioimmunotherapy (RIT) is a safe and active treatment available for non-Hodgkin lymphomas (NHLs). In particular, two monoclonal antibodies raised against CD20, that is Zevalin (⁹⁰Y-ibritumomab-tiuxetan) and Bexxar (¹³¹I-tositumomab) received FDA approval for the treatment of relapsing/refractory indolent or transformed NHLs. RIT is likely the most effective and least toxic anticancer agent in NHLs. However, its use in the clinical setting is still debated and, in case of relapse after optimized rituximab-containing regimens, the efficacy of RIT at standard dosage is suboptimal. Thus, clinical trials were based on the hypothesis that the inclusion of RIT in myeloablative conditioning would allow to obtain improved efficacy and toxicity profiles when compared to myeloablative total-body irradiation and/or high-dose chemotherapy regimens. Standard-activity RIT has a safe toxicity profile, and the utility of pretherapeutic dosimetry in this setting can be disputed. In contrast, dose-escalation clinical protocols require the assessment of radiopharmaceutical biodistribution and dosimetry before the therapeutic injection, as dose constrains for critical organs may be exceeded when RIT is administered at high activities. The aim of the present study was to review and discuss the internal dosimetry protocols that were adopted for non-standard RIT administration in the myeloablative setting before hematopoietic stem cell transplantation in patients with NHLs.

Comparison of Anticancer Drug Toxicities: Paradigm Shift in Adverse Effect Profile

The inception of cancer treatment with chemotherapeutics began in the 1940s with nitrogen mustards that were initially employed as weapons in World War II. Since then, treatment options for different malignancies have evolved over the period of last seventy years. Until the late 1990s, all the chemotherapeutic agents were small molecule chemicals with a highly nonspecific and severe toxicity spectrum. With the landmark approval of rituximab in 1997, a new horizon has opened up for numerous therapeutic antibodies in solid and hematological cancers. Although this transition to large molecules improved the survival and quality of life of cancer patients, this has also coincided with the change in adverse effect patterns. Typically, the anticancer agents are fraught with multifarious adverse effects that negatively impact different organs of cancer patients, which ultimately aggravate their sufferings. In contrast to the small molecules, anticancer antibodies are more targeted toward cancer signaling pathways and exhibit fewer side effects than traditional small molecule chemotherapy treatments. Nevertheless, the interference with the immune system triggers serious inflammation- and infection-related adverse effects. The differences in drug disposition and interaction with human basal pathways contribute to this paradigm shift in adverse effect profile. It is critical that healthcare team members gain a thorough insight of the adverse effect differences between the agents discovered during the last twenty-five years and before. In this review, we summarized the general mechanisms and adverse effects of small and large molecule anticancer drugs that would further our understanding on the toxicity patterns of chemotherapeutic regimens.

Monoclonal antibody based radiopharmaceuticals for imaging and therapy

The concept of personalized medicine has been steadily growing for the past decades. Monoclonal antibodies (mAbs) are undoubtedly playing an important role in the transition away from conventional medical practice to a more tailored approach to deliver the best therapy with the highest safety margin to a specific patient. In certain instances, mAbs and antibody drug conjugates (ADCs) may represent the preferred therapeutic option for several types of cancers due to their high specificity and affinity to the antigen. Monoclonal antibodies can be labeled with specific radionuclides well-suited for PET (Positron Emission Tomography) or gamma camera scintigraphy. The use of radiolabeled mAbs allows the interrogation of specific biomarkers and assessment of tumor heterogeneity in vivo by a single diagnostic imaging scan that includes the whole-body in the field-of-view. Moreover, the same mAb can then be radiolabeled with an analogous radionuclide for the delivery of beta-minus radiation or alpha-particles as part of a radioimmunotherapy (RIT) approach. However, the path to develop, validate, and implement mAb-based radiopharmaceuticals from bench-to-bedside is complex due to the extensive pre-clinical experiments and toxicological studies required, and the necessity of labor-intensive clinical trials that often require multi-time-point imaging and blood draws for internal radiation dosimetry and pharmacokinetics. As more mAb-based radiopharmaceuticals have been developed and evaluated, the opportunities and limitations offered by mAbs have become better defined. Our aim with this manuscript is therefore to provide an overview of the recent advances in the development of mAb-based radiopharmaceuticals and their clinical applications in Oncology.

Adverse events of radioimmunotherapy for non-Hodgkin lymphoma: A systematic review and meta-analysis

Non-Hodgkin's lymphoma continues to be a highly prevalent entity in the general population. Currently, there are multiple treatment schemes based on chemotherapeutic agents with a great success rate. However, there is a non-negligible percentage of patients who may relapse or be refractory. In this sense, new therapeutic options have emerged in the search for adequate responses, such as monoclonal antibodies that target the CD20 molecule. Another valid option is radioimmunotherapy (RIT), which combines using monoclonal antibodies for the specific targeting of malignant cells and radiation to destroy these cells. Despite the promising results that favor RIT in several clinical studies in different target populations and types of NHL, one situation to consider is the association of this therapy and second neoplasms (acute myeloid leukemia (AML) or myelodysplastic syndrome (MSD)). In this sense, we have proposed this meta-analysis to analyze the published information and determine the incidence of this association and determine this therapy's safety.

Ibritumomab Tiuxetan Radioimmunotherapy for Primary Gastrointestinal Follicular Lymphoma

Primary gastrointestinal follicular lymphoma (PGIFL) is characterized by localized involvement of the gastrointestinal (GI) tract. PGIFL usually runs an indolent course. External beam radiation therapy is curative in a substantial proportion of localized follicular lymphomas, but GI toxicities may discourage its use in PGIFL. Ibritumomab tiuxetan radioimmunotherapy (RIT) is a radioimmunoconjugate of anti-CD20 monoclonal antibody linked to chelator tiuxetan and radioisotope. RIT delivers confined high-intensity radiation with short path length specifically targeting lymphoma cells and sparing normal tissue. In this case series report, we included six cases of PGIFL treated with RIT. All patients had low-risk, localized, and nonbulky disease. All patients responded completely and were relapse-free for the duration of follow-up. Hematologic toxicities were seen, but none were serious. RIT is a potentially curative treatment option in PGIFL with a tolerable toxicity profile.

Immunotherapy in the treatment of lymphoma

Relapsed or refractory non-Hodgkin’s lymphomas, especially diffuse large B-cell lymphoma as well as relapsed or refractory Hodgkin lymphomas are hard-to-treat diseases. Patients who do not respond to initial therapy or experience relapse are treated with salvage regimens, and if eligible for aggressive therapy, treatment is continued with high-dose chemotherapy and autologous stem cell transplantation. Current therapy options can cure substantial numbers of patients, however for some it is still an uncurable disease. Numerous new drugs and cell therapies are being investigated for the treatment of relapsed or refractory lymphomas. Different types of immunotherapy options have shown promising results, and some have already become the standard of care. Here, we review immunotherapy options for the treatment of lymphoma and discuss the results, positions, practical aspects, and future directions of different drugs and cellular therapies for the treatment of this disease.

CLDN15 is a novel diagnostic marker for malignant pleural mesothelioma

Malignant mesothelioma is a cancer with a poor survival rate. It is difficult to diagnose mesotheliomas because they show a variety of histological patterns similar to those of various other cancers. However, since currently used positive markers for mesotheliomas may show false positives or false negatives, a novel mesothelial positive marker is required. In the present study, we screened 25 claudins and found that claudin-15 is expressed in the mesothelial cells. We made new rat anti-human claudin-15 (CLDN15) monoclonal antibodies that selectively recognize CLDN15, and investigated whether CLDN15 is a good positive marker for malignant pleural mesotheliomas (MPMs) using MPM tissue samples by immunohistochemistry and semi-quantification of the expression level using an immunoreactive score (IRS) method. Of 42 MPM samples, 83% were positive for CLDN15. The positive ratio was equal to or greater than other positive markers for MPMs including calretinin (81%), WT-1 (50%), and D2-40 (81%). In 50 lung adenocarcinoma sections, four cases were positive for CLDN15 and the specificity (92%) was comparable with other markers (90–100%). Notably, CLDN15 was rarely detected in 24 non-mesothelial tumors in the tissue microarray (12/327 cases). In conclusion, CLDN15 can be used in the clinical setting as a positive marker for MPM diagnosis.

Patient-reported long-term quality of life after tisagenlecleucel in relapsed/refractory diffuse large B-cell lymphoma

The JULIET phase 2 trial evaluated a single infusion of tisagenlecleucel in adult patients with relapsed/refractory (r/r) diffuse large B-cell lymphoma (DLBCL). The objective of the current analysis was to evaluate patient-reported health-related quality of life (HRQoL) with a median follow-up of 19.3 months among patients infused with a single dose of tisagenlecleucel. Patients enrolled were ≥18 years of age with r/r DLBCL after ≥2 lines of therapy and had either undergone a failed autologous stem cell transplant or were ineligible for the procedure. Two validated HRQoL instruments, Functional Assessment of Cancer Therapy-Lymphoma (FACT-Lym) and Short Form-36 (SF-36) Health Survey, were used to measure HRQoL at baseline and months 3, 6, 12, and 18. At data cutoff (21 May 2018), 115 patients had received tisagenlecleucel infusion. Among the 99 patients evaluated, overall response rate was 54%, and 40% of patients achieved complete response (CR). Initially, 108 patients completed the HRQoL assessments at baseline, including 57 patients who eventually achieved CR or partial response (PR). Further, 30 and 21 patients in clinical response who completed assessments at baseline also completed assessments at months 12 and 18, respectively. Patients who achieved CR or PR sustained HRQoL improvement in all FACT scores at all time points. SF-36 instruments showed improvement above the minimal clinically important differences on 5 of 8 subscales. Long-term follow-up in the phase 2 JULIET study demonstrated that patients with r/r DLBCL who respond to tisagenlecleucel therapy had sustained, clinically meaningful improvements in HRQoL. This trial was registered at www.clinicaltrials.gov as #NCT02445248.

Phase 1/2a study of 177Lu-lilotomab satetraxetan in relapsed/refractory indolent non-Hodgkin lymphoma

For patients with indolent non-Hodgkin lymphoma who fail initial anti-CD20-based immunochemotherapy or develop relapsed or refractory disease, there remains a significant unmet clinical need for new therapeutic approaches to improve outcomes and quality of life. 177Lu-lilotomab satetraxetan is a next-generation single-dose CD37-directed radioimmunotherapy (RIT) which was investigated in a phase 1/2a study in 74 patients with relapsed/refractory indolent non-Hodgkin B-cell lymphoma, including 57 patients with follicular lymphoma (FL). To improve targeting of 177Lu-lilotomab satetraxetan to tumor tissue and decrease hematologic toxicity, its administration was preceded by the anti-CD20 monoclonal antibody rituximab and the "cold" anti-CD37 antibody lilotomab. The most common adverse events (AEs) were reversible grade 3/4 neutropenia (31.6%) and thrombocytopenia (26.3%) with neutrophil and platelet count nadirs 5 to 7 weeks after RIT. The most frequent nonhematologic AE was grade 1/2 nausea (15.8%). With a single administration, the overall response rate was 61% (65% in patients with FL), including 30% complete responses. For FL with ≥2 prior therapies (n = 37), the overall response rate was 70%, including 32% complete responses. For patients with rituximab-refractory FL ≥2 prior therapies (n = 21), the overall response rate was 67%, and the complete response rate was 24%. The overall median duration of response was 13.6 months (32.0 months for patients with a complete response). 177Lu-lilotomab satetraxetan may provide a valuable alternative treatment approach in relapsed/refractory non-Hodgkin lymphoma, particularly in patients with comorbidities unsuitable for more intensive approaches. This trial was registered at www.clinicaltrials.gov as #NCT01796171.

Chemotherapy-Free Management of Follicular and Marginal Zone Lymphoma

Many patients with follicular (FL) or marginal zone lymphoma (MZL) are not eligible to receive immunochemotherapy due to advanced age or comorbidities. Recent innovations in the treatment of these indolent lymphomas provide options for multiple lines of chemotherapy-free management. More research is needed to determine which older patients are best served by a chemotherapy-free approach in the context of geriatric vulnerabilities. In the first line, regardless of disease burden, rituximab monotherapy can provide high rates of disease control with minimal toxicity, while judicious use of brief maintenance extends the duration of response. Radioimmunotherapy using ibritumomab tiuxetan is an effective and safe post-rituximab consolidation for older patients who have <25% bone marrow involvement. The combination of rituximab and lenalidomide, although “chemotherapy-free”, does not improve tolerability over immunochemotherapy. However, studies support lower doses and shorter duration of lenalidomide exposure as a means to improve safety without materially compromising efficacy for older individuals. Extranodal MZL can often be effectively controlled with low-dose radiation therapy, and splenic MZL has excellent outcomes with rituximab monotherapy. For many patients with relapsed FL/MZL, simple retreatment with anti-CD20 antibodies will prove sufficient. Other currently available options for relapsed/refractory disease include ibritumomab tiuxetan, lenalidomide with rituximab, umbralisib as a potentially less toxic PI3K inhibitor, ibrutinib (for MZL), and tazemetostat (for FL, especially with EZH2 mutation). Emerging data with novel forms of immunotherapy (antibody-drug conjugates like polatuzumab vedotin or loncastuximab tesirine; T-cell-engaging bispecific antibodies like mosunetuzumab or epcoritamab; and chimeric antigen receptor CAR T-cells like axicabtagene ciloleucel) suggest that immune-directed approaches can produce very high and potentially durable responses in FL/MZL with limited toxicities, further obviating the need for chemotherapy.

Thorium-227-Labeled Anti-CD22 Antibody (BAY 1862864) in Relapsed/Refractory CD22-Positive Non-Hodgkin Lymphoma: A First-in-Human, Phase I Study

Background: BAY 1862864 is an α-particle emitting thorium-227-labeled CD22-targeting antibody. This first-in-human dose-escalation phase I study evaluated BAY 1862864 in patients with CD22-positive relapsed/refractory B cell non-Hodgkin lymphoma (R/R-NHL). Materials and Methods: BAY 1862864 intravenous injections were administered at the starting thorium-227 radioactivity dose of 1.5 MBq (2 or 10 mg antibody), and the radioactivity dose escalated in ∼1.5 MBq increments (10 mg antibody) until the maximum tolerated dose (MTD) was reported. The primary objective was to determine the safety, tolerability, and MTD. Results: Twenty-one patients received BAY 1862864. Two dose-limiting toxicities (grade 3 febrile neutropenia and grade 4 thrombocytopenia) were reported in one patient in the 4.6 MBq (10 mg antibody) cohort. The MTD was not reached. Ten (48%) patients reported grade ≥3 treatment-emergent adverse events, with the most common being neutropenia, thrombocytopenia, and leukopenia, each occurring in 3 (14%) patients. Pharmacokinetics demonstrated the dose proportionality and stability of BAY 1862864 in the blood. The objective response rate (ORR) was 25% (5/21 patients) according to the LUGANO 2014 criteria, including 1 complete and 4 partial responses. The ORR was 11% (1/9) and 30% (3/10) in patients with relapsed high- and low-grade lymphomas, respectively. Conclusions: BAY 1862864 was safe and tolerated in patients with R/R-NHL. The Clinical Trial Registration numbers: NCT02581878 and EudraCT 2014-004140-36.

Perspectives on metals-based radioimmunotherapy (RIT): moving forward

Radioimmunotherapy (RIT) is FDA-approved for the clinical management of liquid malignancies, however, its use for solid malignancies remains a challenge. The putative benefit of RIT lies in selective targeting of antigens expressed on the tumor surface using monoclonal antibodies, to systemically deliver cytotoxic radionuclides. The past several decades yielded dramatic improvements in the quality, quantity, recent commercial availability of alpha-, beta- and Auger Electron-emitting therapeutic radiometals. Investigators have created new or improved existing bifunctional chelators. These bifunctional chelators bind radiometals and can be coupled to antigen-specific antibodies. In this review, we discuss approaches to develop radiometal-based RITs, including the selection of radiometals, chelators and antibody platforms (i.e. full-length, F(ab')2, Fab, minibodies, diabodies, scFv-Fc and nanobodies). We cite examples of the performance of RIT in the clinic, describe challenges to its implementation, and offer insights to address gaps toward translation.

Richter Syndrome

PURPOSE OF REVIEW

Richter syndrome (RS) is an uncommon but aggressive evolution of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL). RS is an unmet clinical need in the field of CLL. Recent advances in understanding the biology of this condition provide the rationale for testing new therapeutic concepts in order to improve the outcome of patients developing RS, which is so far poor. In this review, we summarize disease characteristics and available therapeutic options for RS.

RECENT FINDINGS

Current regimens with novel agents in monotherapy have shown little impact on survival. Nevertheless, the better reported outcome for RS has been achieved with the combination of chemo-immunotherapy with a novel agent, confirming the synergistic effect of the approaches. Still, the frailty of this population may impose a less toxic management leaving most patients with no reasonable therapeutic option. Treatment options for RS need to be further expanded. Preclinical models in current development may allow to explore actionable pathways and identify new drug targeted combinations.

Delta-like 1 homolog (DLK1) as a possible therapeutic target and its application to radioimmunotherapy using 125I-labelled anti-DLK1 antibody in lung cancer models (HOT1801 and FIGHT004)

OBJECTIVES

Delta-like 1 homolog (DLK1) is a non-canonical Notch ligand known to be expressed in several cancers but whose role in lung cancer is not yet fully understood. We sought to confirm DLK1 expression in small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC), and to examine DLK1's clinical significance. Furthermore, we examined the possible utility of DLK1 as a novel target in radioimmunotherapy (RIT).

METHODS

We retrospectively assessed the correlation between clinical features and DLK1 expression by immunohistochemistry in resected specimens from 112 patients with SCLC and 101 patients with NSCLC. Moreover, we performed cell and animal experiments, and examined the possibility of RIT targeting DLK1 in SCLC using iodine-125 (¹²⁵I) -labeled anti-DLK1 antibody, knowing that ¹²⁵I can be replaced with the alpha-particle-emitter astatine-211 (²¹¹At).

RESULTS

In SCLC and NSCLC, 20.5 % (23/112) and 16.8 % (17/101) of patients (respectively) had DLK1-positive tumors. In NSCLC, DLK1 expression was associated with recurrence-free survival (P < 0.01) but not with overall survival. In SCLC, there was no association between DLK1 expression and survival. In addition, ¹²⁵I-labeled anti-DLK1 antibody specifically targeted DLK1 on human SCLC tumor cell lines. Furthermore, ¹²⁵I-labeled anti-DLK1 antibody was incorporated into tumor tissue in a mouse model.

CONCLUSION

A proportion of SCLC and NSCLC exhibits DLK1 expression. As a clinical feature, DLK1 expression could be a promising prognostic factor for recurrence in patients with resected NSCLC. In addition, DLK1 could serve as a new therapeutic target, including RIT, as suggested by our pilot study using a radiolabeled anti-DLK1 antibody in SCLC.

Astatine-211 labelled a small molecule peptide: specific cell killing in vitro and targeted therapy in a nude-mouse model

Extensive interest in the development of α-emitting radionuclides astatine-211 (211At) stems from the potential superiority for the treatment of smaller tumors, disseminated disease, and metastatic disease. VP2, a small molecule fusion peptide, can specifically bind to the VPAC1 receptor which is over-expressed in malignant epithelial tumors. In our recent study, we performed the preparation of 211At labelled VP2 through a one-step method. In this work, we explored the targeted radionuclide therapy with [211At]At-SPC-VP2 in vitro and in vivo. The cytotoxicity and specific cell killing of [211At]At-SPC-VP2 were evaluated using the CCK-8 assay. Compared with the [211At]NaAt, the VPAC1-targeted radionuclide compound [211At]At-SPC-VP2 showed more effective cytotoxicity in vitro. Targeted radioactive therapy trial was carried out in non-small-cell lung cancer (NSCLC) xenograft mice. For the therapy experiment, 4 groups of mice were injected via the tail vein with 370 kBq, 550 kBq, 740 kBq, 3 × ∼246 kBq of [211At]At-SPC-VP2, of which the second and third injections were given 4 and 8 days after the first injection, respectively. As controls, animals were treated with saline or 550 kBq [211At]NaAt. The body weight and tumor size of mice were monitored before the administration and every 2 days thereafter. Cytotoxic radiation of partial tissue samples such as kidneys, liver and stomach of mice were assessed by immunohistochemical examination. The tumor growth was inhibited and significantly improved survival was achieved in mice treated with [211At]At-SPC-VP2, two-fold prolongation of survival compared with the control group, which received normal saline or 550 kBq [211At]NaAt. No renal or hepatic toxicity was observed in the mice receiving [211At]At-SPC-VP2, but gastric pathological sections showed 211At uptake in stomach resulting in later toxicity, highlighting the importance of further enhancing the stability of labelled compounds.

Skin-Associated B Cells in the Pathogenesis of Cutaneous Autoimmune Diseases-Implications for Therapeutic Approaches

B lymphocytes are crucial mediators of systemic immune responses and are known to be substantial in the pathogenesis of autoimmune diseases with cutaneous manifestations. Amongst them are lupus erythematosus, dermatomyositis, systemic sclerosis and psoriasis, and particularly those driven by autoantibodies such as pemphigus and pemphigoid. However, the concept of autoreactive skin-associated B cells, which may reside in the skin and locally contribute to chronic inflammation, is gradually evolving. These cells are believed to differ from B cells of primary and secondary lymphoid organs and may provide additional features besides autoantibody production, including cytokine expression and crosstalk to autoreactive T cells in an antigen-presenting manner. In chronically inflamed skin, B cells may appear in tertiary lymphoid structures. Those abnormal lymph node-like structures comprise a network of immune and stromal cells possibly enriched by vascular structures and thus constitute an ideal niche for local autoimmune responses. In this review, we describe current considerations of different B cell subsets and their assumed role in skin autoimmunity. Moreover, we discuss traditional and B cell-associated approaches for the treatment of autoimmune skin diseases, including drugs targeting B cells (e.g., CD19- and CD20-antibodies), plasma cells (e.g., proteasome inhibitors, CXCR4 antagonists), activated pathways (such as BTK- and PI3K-inhibitors) and associated activator molecules (BLyS, APRIL).

Chemotherapy combinations for B-cell lymphoma and chemo-free approach in elderly patients: an update on best practice

INTRODUCTION

Elderly patients represent a consistent portion of new diagnoses of B cell Non-Hodgkin Lymphoma (B-NHL). The treatment approach in this setting can be challenging for clinicians due to treatment toxicities and patients' comorbidities to deal with. Immunochemotherapy still represents the main option in the front-line setting for diffuse large B cell lymphoma (DLBCL), follicular lymphoma (FL), and mantle cell lymphoma (MCL), with different options to choose depending on patient characteristics. In the last decade, a number of new drugs and combinations have been investigated, demonstrating efficacy and safety even in the older population and extending the spectrum of treatment choices for this setting.

AREAS COVERED

This article reviews the majority data in literature on immunochemotherapy regimens and chemo-free approaches available for DLBCL, FL, and MCL in the elderly, both in front-line and relapse/refractory setting, the incoming drugs and how to identify the best option for each patient.

EXPERT OPINION

The therapeutic approach for elderly B-NHL is challenging and a tailored approach guided by a geriatric assessment is mandatory, in order to optimize efficacy and minimize treatment-related toxicities. The more extended use of biological drugs may potentially lead to prolonged survival with reduction of toxicities and improved quality of life.

Preclinical Characterization of the Radioimmunoconjugate 111In or 90Y-FF-21101 Against a P-Cadherin-Expressing Tumor in a Mouse Xenograft Model and a Nonhuman Primate

P-cadherin is overexpressed in various cancers and can be a target for radioimmunotherapy. We investigated the preclinical pharmacokinetics and pharmacology of FF-21101, an ¹¹¹In- or ⁹⁰Y-conjugated monoclonal antibody against P-cadherin, to evaluate its clinical applications. Methods: The radiochemical purity, binding affinity, and in vitro serum stability of ¹¹¹In or ⁹⁰Y-labeled FF-21101 were evaluated. The pharmacokinetics of ¹¹¹In or ⁹⁰Y-FF-21101 were compared in normal mice. Tumor accumulation after ¹¹¹In-FF-21101 administration was investigated in mice bearing subcutaneous tumors with high (NCI-H1373), moderate (EBC-1), or no (A549) P-cadherin expression. The tumor suppression effect after a single intravenous injection of ⁹⁰Y-FF-21101 was assessed in NCI-H1373 and EBC-1 mouse xenograft models. The relationship between antibody dose and tumor accumulation was investigated in the NCI-H1373 mouse xenograft model. The absorbed radiation dose in humans after injection of ⁹⁰Y-FF-21101 was estimated using γ-camera images of cynomolgus monkeys. Results: The radiochemical purities of ¹¹¹In- and ⁹⁰Y-FF-21101 were 98.2% ± 2.5% (n = 9) and 99.3% ± 0.6% (n = 5), respectively. The dissociation constants were 1.083 nM for ¹¹¹In-FF-21101 and 1.367 nM for ⁹⁰Y-FF-21101. Both ¹¹¹In- and ⁹⁰Y-FF-21101 were stable in human serum after 96 h of incubation and exhibited similar pharmacokinetics in normal mice. The tumor accumulation of ¹¹¹In-FF-21101 was closely related to the intensity of P-cadherin expression in the cells. ⁹⁰Y-FF-21101 showed significant tumor growth inhibition, indicating that NCI-H1373 and EBC-1 recurrence was not observed after intravenous administration of 3.7 and 7.4 MBq, respectively of ⁹⁰Y-FF-21101 per animal. Tumor uptake in the mouse xenograft model and estimated absorbed radiation doses in the spleen of monkeys decreased with increasing antibody doses of ¹¹¹In-FF-21101. Conversely, the estimated absorbed radiation dose in the red marrow increased with increasing antibody dose. An antibody dose of 4.8 mg/m² was considered appropriate for humans, on the basis of efficacy and safety. The maximum tolerated administered activity of ⁹⁰Y-FF-21101 was estimated to be 2,886 MBq/human. Conclusion: FF-21101 radioimmunotherapy exhibited high antitumor affinity and antitumor efficacy in mouse xenograft models. Extrapolation of the pharmacokinetics in monkeys to humans suggests the potential for clinical application of FF-21101 for treating P-cadherin–expressing tumor.

Radiopharmaceutical therapy in cancer: clinical advances and challenges

Radiopharmaceutical therapy (RPT) is emerging as a safe and effective targeted approach to treating many types of cancer. In RPT, radiation is systemically or locally delivered using pharmaceuticals that either bind preferentially to cancer cells or accumulate by physiological mechanisms. Almost all radionuclides used in RPT emit photons that can be imaged, enabling non-invasive visualization of the biodistribution of the therapeutic agent. Compared with almost all other systemic cancer treatment options, RPT has shown efficacy with minimal toxicity. With the recent FDA approval of several RPT agents, the remarkable potential of this treatment is now being recognized. This Review covers the fundamental properties, clinical development and associated challenges of RPT.

Radiopharmaceutical therapy is emerging as a safe and effective approach for the treatment of cancer, offering several advantages over existing therapeutic strategies. Here, Sgouros and colleagues provide an overview of the fundamental properties of radiopharmaceutical therapy, discuss agents in use and in clinical development and highlight the associated translational challenges.

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

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

ImmunoPET in Multiple Myeloma-What? So What? Now What?

Despite constant progress over the past three decades, multiple myeloma (MM) is still an incurable disease, and the identification of new biomarkers to better select patients and adapt therapy is more relevant than ever. Recently, the introduction of therapeutic monoclonal antibodies (mAbs) (including direct-targeting mAbs and immune checkpoint inhibitors) appears to have changed the paradigm of MM management, emphasizing the opportunity to cure MM patients through an immunotherapeutic approach. In this context, immuno-positron emission tomography (immunoPET), combining the high sensitivity and resolution of a PET camera with the specificity of a radiolabelled mAb, holds the capability to cement this new treatment paradigm for MM patients. It has the potential to non-invasively monitor the distribution of therapeutic antibodies or directly monitor biomarkers on MM cells, and to allow direct observation of potential changes over time and in response to various therapeutic interventions. Tumor response could, in the future, be anticipated more effectively to provide individualized treatment plans tailored to patients according to their unique imaging signatures. This work explores the important role played by immunotherapeutics in the management of MM, and focuses on some of the challenges for this drug class and the significant interest of companion imaging agents such as immunoPET.

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

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

Radioimmunotherapy in Non-Hodgkin's Lymphoma: Retrospective Adverse Event Profiling of Zevalin and Bexxar

The development of monoclonal antibodies has dramatically changed the outcome of patients with non-Hodgkin’s lymphoma (NHL), the most common hematological malignancy. However, despite the satisfying results of monoclonal antibody treatment, only few NHL patients are permanently cured with single-agent therapies. In this context, radioimmunotherapy, the administration of radionuclides conjugated to monoclonal antibodies, is aimed to augment the single-agent efficacy of immunotherapy in order to deliver targeted radiation to tumors, particularly CD20+ B-cell lymphomas. Based on evidence from several trials in NHL, the radiolabeled antibodies ⁹⁰Y-ibritumomab tiuxetan (Zevalin, Spectrum Pharmaceuticals) and ¹³¹I-tositumomab (Bexxar, GlaxoSmithKline) received FDA approval in 2002 and 2003, respectively. However, none of the two radioimmunotherapeutic agents has been broadly applied in clinical practice. The main reason for the under-utilization of radioimmunotherapy includes economic and logistic considerations. However, concerns about potential side effects have also been raised. Driven by these developments, we performed retrospective analysis of adverse events reporting Zevalin or Bexxar, extracted from the FDA’s Adverse Event Reporting System (FAERS) and the World Health Organization’s VigiBase repository. Our results indicate that the two radioimmunotherapeutic agents have both related and distinct side effect profiles and confirm their known toxicological considerations. Our work also suggests that computational analysis of real-world post-marketing data can provide informative clinical insights. While more prospective studies are necessary to fully characterize the efficacy and safety of radioimmunotherapy, we expect that it has not yet reached its full therapeutic potential in modern hematological oncology.

Multicenter, Open-Label, Phase II Study of Bendamustine and Rituximab Followed by 90-Yttrium (Y) Ibritumomab Tiuxetan for Untreated Follicular Lymphoma (Fol-BRITe)

PURPOSE

Bendamustine and rituximab (BR) has been established as a superior frontline therapy over R-CHOP in the treatment of follicular lymphoma (FL). Yttrium-90 Ibritumomab tiuxetan (⁹⁰YIT) is an effective consolidation strategy after chemotherapy induction. This prospective, single-arm, multicenter, phase II trial evaluated the response rate, progression-free survival (PFS), and tolerability of BR followed by consolidation with ⁹⁰YIT in patients with untreated FL.

PATIENTS AND METHODS

The study included grade 1 to 3a FL patients aged ≥18 years, chemotherapy-naïve, and requiring treatment for stage II-IV disease. Study treatment included an initial rituximab treatment, followed by four cycles of BR. Patients were eligible for consolidation with ⁹⁰YIT, 6 to 12 weeks after BR, if they obtained at least a partial response after induction had adequate count recovery and bone marrow infiltration < 25%.

RESULTS

Thirty-nine patients were treated. Eighty-two percent had an intermediate or high-risk Follicular Lymphoma International Prognostic Index score, and 6 of 39 (15%) were grade 3a. The response rate was 94.8%, and the complete response(CR)/CR unconfirmed (CRu) rate was 77% in the intention-to-treat analysis. The conversion rate from PR to CR/Cru after ⁹⁰YIT was 81%. After median follow-up of 45 months, the PFS was 0.71 (95% confidence interval, 0.57-0.89).

CONCLUSIONS

This report demonstrates that four cycles of BR followed by consolidation with ⁹⁰YIT achieve high response rates that are durable. In addition, consolidation with ⁹⁰YIT results in a high conversion rate of PR to CR/CRu. A short course of BR followed by ⁹⁰YIT is a safe and effective regimen for frontline treatment of FL.

Development of Bispecific NT-PSMA Heterodimer for Prostate Cancer Imaging: A Potential Approach to Address Tumor Heterogeneity

Prostate cancer is a heterogeneous disease with a poor survival rate at late stage. In this report, a dual targeting PET agent was developed to partially address the tumor heterogeneity issue. The heterodimer F-BCN-PSMA-NT was designed to target PSMA and neurotensin receptor1 (NTR1), both of which have demonstrated great potential in prostate cancer management. The heterodimer was synthesized through the conjugation of Glu-urea-lys(Ahx) (PSMA targeting motif) and NT20.3 (NTR1 targeting motif) to a symmetric trifunctional linker, bearing an azide group for further modification. Radio-labeling was performed using strain promoted azide-alkyne click reaction with high yield. Cell based assays suggested that F-BCN-PSMA-NT has comparable or only slightly reduced binding affinity with the corresponding monomers. Small animal PET clearly demonstrated that the heterodimer probe has prominent uptake not only in NTR1 positive/PSMA negative PC-3 tumors (1.4 ± 0.3%ID/g), but also in the PSMA positive/NTR1 negative LnCap tumors (1.3 ± 0.2%ID/g). The tracer showed comparable tumor to background ratio with each monomer. In summary, prostate cancer is a heterogeneous disease in need of improved diagnostics and treatments. The PSMA-NT heterodimer represents a new class of molecules that can be used to target two distinct antigens related to prostate cancer. In addition to the imaging applications demonstrated in this study, the agent also holds great potential on the treatment of heterogeneous prostate cancer.

Consolidation with 90Y ibritumomab tiuxetan radioimmunotherapy in mantle cell lymphoma patients ineligible for high dose therapy: results of the phase II multicentre Polish Lymphoma Research Group trial, after 8-year long follow-up

Polish Lymphoma Research Group performed a phase-II trial to test whether ⁹⁰Y ibritumomab tiuxetan radioimmunotherapy (Y90) may constitute an alternative consolidation for mantle cell lymphoma patients unfit for high-dose therapy. Forty-six patients were consolidated with Y90 following response to the 1st (n = 34) or 2nd line (n = 12) (immuno)chemotherapy. Majority of the patients had advanced disease (stage IV and presence of B-symptoms in 85% and 70%, respectively) and high MIPI (5.8, range 4-7). Consolidation with Y90 increased the complete remission (CR) rate obtained by the 1st line therapy from 41% to 91% and allowed for median PFS of 3.3 and OS of 6.5 years. In the first relapse, CR rate increased from 16% to 75%, while median PFS and OS totaled 2.2 and 6.5 years, respectively. At 8 years, 30% of patients, consolidated in the 1st line CR were alive, without relapse. Toxicity associated with Y90 is manageable, more severe after fludarabine-based regimens.

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.

Novel treatment approaches and future perspectives in follicular lymphoma

Follicular lymphoma (FL) is a common B-cell malignancy characterized by relatively indolent growth and incurability with an expected lifetime course of serial intermittent treatment courses. Many patients with FL have lives shortened by the disease and despite a relatively favorable prognosis relative to other incurable systemic malignancies, optimal management of FL has not been achieved. This review focuses on identifying both patients for whom novel therapies might be most beneficial as well as systematically reviewing novel strategies at various levels of investigation. Prognostic markers incorporating clinical measurements and tumor genetics are discussed, yet at the time of diagnosis do not yet powerfully discriminate patients for whom specific strategies are beneficial. Reassessment of prognosis after evaluating the response to initial therapy is the most powerful identifier of those in need of novel management strategies. For initial therapy of high burden systemic disease, anti-CD20 antibody along with chemotherapy or immunomodulators all offer relatively similar effects on overall survival with subtly different effects on progression-free survival and quality of life. Several new agents currently under investigation in the upfront setting are discussed. Perhaps the best testing ground for novel therapies is in patients with early relapse following initial immunochemotherapy. Ongoing research in multiple therapy classes including, novel monoclonal antibodies, antibody drug conjugates, immunomodulatory agents, intracellular pathway inhibitors, immune checkpoint inhibitors, and epigenetic regulators are discussed herein.

90 Y-ibritumomab-tiuxetan as a therapeutic alternative for follicular lymphoma (FL): A single-center experience

BACKGROUND

Follicular lymphoma (FL) is the most frequent indolent lymphoma subtype in adults. Maintenance therapy with rituximab is frequently applied to FL patients with complete or partial response following initial chemoimmunotherapy. However, radioimmunotherapy with ⁹⁰ Y-ibritumomab-tiuxetan represents a therapeutic alternative.

METHODS

To compare the clinical and the prognostic impact of both therapies, a study collective of n = 56 patients diagnosed with indolent B-cell lymphoma was retrospectively investigated. The study collective was subdivided into two groups: n = 36 patients treated with rituximab maintenance therapy vs n = 20 patients treated with ⁹⁰ Y-ibritumomab-tiuxetan.

RESULTS

No prognostic differences for performance status, FLIPI score, gender, or B-symptoms were found for ⁹⁰ Y-ibritumomab-tiuxetan or rituximab maintenance therapy. Overall survival rates and progression-free survival did not differ between both maintenance therapies.

CONCLUSION

Our retrospective single-center analysis of two patient groups without major differences in prognostic parameters revealed similar outcome with two different maintenance therapies. Hence, ⁹⁰ Y-ibritumomab-tiuxetan therapy might offer a valuable alternative treatment option for FL patients with partial response. However, large prospective trials are needed to confirm the reported findings.