90Y-Daclizumab (Anti-CD25), High-Dose Carmustine, Etoposide, Cytarabine, and Melphalan Chemotherapy and Autologous Hematopoietic Stem Cell Transplant Yielded Sustained Complete Remissions in 4 Patients with Recurrent Hodgkin's Lymphoma

Background: Despite advances in therapy of Hodgkin's lymphoma (HL), a proportion of patients will not respond or relapse. The authors had previously identified CD25, IL-2Rα, as a target for systemic radioimmunotherapy of HL since most normal cells do not express CD25, but it is expressed by a minority of Hodgkin/Reed-Sternberg (HRS) cells and most Tregs rosetting around HRS cells. Study Design and Treatment: This was a single institution, nonrandomized, open-label phase I/II trial of radiolabeled ⁹⁰Y-daclizumab, an anti-CD25 monoclonal antibody, BEAM (carmustine, etoposide, cytarabine, and melphalan) conditioning treatment followed by autologous hematopoietic stem cell transplant (ASCT). Four patients with refractory and relapsed HL were treated in this trial with 3 patients receiving a single dose of 564.6-574.6 MBq ⁹⁰Y-daclizumab and the fourth patient receiving two doses of 580.9-566.1 MBq ⁹⁰Y-daclizumab followed by high-dose chemotherapy and ASCT. Results: All 4 evaluable patients treated with ⁹⁰Y-daclizumab obtained complete responses (CRs) that are ongoing 4.5-7 years following their stem cell transplant. The spectrum and severity of adverse events were mild and more importantly none of the patients, including several with multiple therapies before this treatment, developed the myelodysplastic syndrome. Discussion: Targeting by daclizumab was not directed primarily at tumor cells, but rather the nonmalignant CD25-expressing T cells adjacent to the HRS cells and ⁹⁰Y-daclizumab provided strong enough β emissions to kill CD25-negative tumor cells at a distance by a crossfire effect. Furthermore, the strong β irradiation killed normal cells in the tumor microenvironment. Conclusions: ⁹⁰Y-daclizumab (anti-CD25), high-dose BEAM chemotherapy and ASCT was well tolerated and yielded sustained complete remissions in all 4 patients with recurrent HL patients who completed their treatment. Significance: Despite advances, a proportion of patients with HL will not have a CR to their initial treatment, and some with CRs will relapse. They demonstrated that the addition of ⁹⁰Y-daclizumab into the preconditioning regimen for refractory and relapsed HL patients with high-dose BEAM chemotherapy and ASCT provided sustained CRs in the 4 patients studied. Two of these patients were highly refractory to multiple prior treatments with bulky disease at entry into this study, including 1 patient who never entered a remission and had failed 6 different therapeutic regimens. Despite the small number of patients treated in this study, the sustained clinical benefit in these patients indicates a highly effective treatment. The daclizumab was directed primarily not at HRS cells themselves but toward nonmalignant T cells rosetting around malignant cells. ⁹⁰Y provided strong β emissions that killed antigen nonexpressing tumor cells at a distance by a crossfire effect. Furthermore, the strong β radiation killed normal cells in the tumor microenvironment that nurtured the malignant cells in the lymphomatous mass. The present study supports expanded analysis of ⁹⁰Y-daclizumab as part of the regimen of ASCT in patients with refractory and relapsed HL.

90Y-daclizumab, an anti-CD25 monoclonal antibody, provided responses in 50% of patients with relapsed Hodgkin's lymphoma

Despite significant advances in the treatment of Hodgkin's lymphoma (HL), a significant proportion of patients will not respond or will subsequently relapse. We identified CD25, the IL-2 receptor alpha subunit, as a favorable target for systemic radioimmunotherapy of HL. The scientific basis for the clinical trial was that, although most normal cells with exception of Treg cells do not express CD25, it is expressed by a minority of Reed-Sternberg cells and by most polyclonal T cells rosetting around Reed-Sternberg cells. Forty-six patients with refractory and relapsed HL were evaluated with up to seven i.v. infusions of the radiolabeled anti-CD25 antibody (90)Y-daclizumab. (90)Y provides strong β emissions that kill tumor cells at a distance by a crossfire effect. In 46 evaluable HL patients treated with (90)Y-daclizumab there were 14 complete responses and nine partial responses; 14 patients had stable disease, and nine progressed. Responses were observed both in patients whose Reed-Sternberg cells expressed CD25 and in those whose neoplastic cells were CD25(-) provided that associated rosetting T cells expressed CD25. As assessed using phosphorylated H2AX (γ-H2AX) as a bioindicator of the effects of radiation exposure, predominantly nonmalignant cells in the tumor microenvironment manifested DNA damage, as reflected by increased expression of γ-H2AX. Toxicities were transient bone-marrow suppression and myelodysplastic syndrome in six patients who had not been evaluated with bone-marrow karyotype analyses before therapy. In conclusion, repeated (90)Y-daclizumab infusions directed predominantly toward nonmalignant T cells rosetting around Reed-Sternberg cells provided meaningful therapy for select HL patients.

Delivery Systems for Lymphatic Targeting

The lymphatic system has a critical role in the immune system’s recognition and response to disease, and it is an additional circulatory system throughout the entire body. Most solid cancers primarily spread from the main site via the tumour’s surrounding lymphatics before haematological dissemination. Targeting drugs to lymphatic system is quite complicated because of its intricate physiology. Therefore, it tends to be an important target for developing novel therapeutics. Currently, nanocarriers have encouraged the lymphatic targeting, but still there are challenges of locating drugs and bioactives to specific sites, maintaining desired action and crossing all the physiological barriers. Lymphatic therapy using drug-encapsulated colloidal carriers especially liposomes and solid lipid nanoparticles emerges as a new technology to provide better penetration into the lymphatics where residual disease exists. Optimising the proper procedure, selecting the proper delivery route and target area and making use of surface engineering tool, better carrier for lymphotropic system can be achieved. Thus, new methods of delivering drugs and other carriers to lymph nodes are currently under investigation.

ADME of antibody-maytansinoid conjugates

The concept of treating cancer with antibody-drug conjugates (ADCs) has gained momentum with the favorable activity and safety of trastuzumab emtansine (T-DM1), SAR3419, and lorvotuzumab mertansine (IMGN901). All three ADCs utilize maytansinoid cell-killing agents which target tubulin and suppress microtubule dynamics. Each ADC utilizes a different optimized chemical linker to attach the maytansinoid to the antibody. Characterizing the absorption, distribution, metabolism, and excretion (ADME) of these ADCs in preclinical animal models is important to understanding their efficacy and safety profiles. The ADME properties of these ADCs in rodents were inferred from studies with radio-labeled ADCs prepared with nonbinding antibodies since T-DM1, SAR3419, IMGN901 all lack cross-reactivity with rodent antigens. For studies exploring tumor localization and activation in tumor-bearing mice, tritium-labeled T-DM1, SAR3419, and IMGN901 were utilized. The chemical nature of the linker was found to have a significant impact on the ADME properties of these ADCs-particularly on the plasma pharmacokinetics and observed catabolites in tumor and liver tissues. Despite these differences, T-DM1, SAR3419, and IMGN901 were all found to facilitate efficient deliveries of active maytansinoid catabolites to the tumor tissue in mouse xenograft models. In addition, all three ADCs were effectively detoxified during hepatobiliary elimination in rodents.

Antibody delivery of drugs and radionuclides: factors influencing clinical pharmacology

The therapeutic rationale of antibody conjugates is the selective delivery of a cytotoxin to tumor cells via binding and internalization of the monoclonal antibodies to a specific cell-surface antigen, thereby enhancing the therapeutic index of the cytotoxin. The key structural and functional components of an antibody conjugate are the antibody, the linker and the cytotoxin (chemical or radionuclide) with each component being critical for the successful development of the conjugate. Considerable efforts have been made in understanding the pharmacokinetics, pharmacodynamics, tissue distribution, metabolism and pharmacologic effects of these complex macromolecular entities. The purpose of this article is to discuss the properties and various structural components of antibody conjugates that influence their clinical pharmacology.

Anti-CD30 Antibodies for Hodgkin lymphoma

Treatment of refractory or relapsed classical Hodgkin lymphoma (HL) remains challenging, but targeted immunotherapy has recently emerged as a potential treatment option for these patients. Although first-generation monoclonal anti-CD30 antibodies proved disappointing, current efforts to modify anti-CD30 antibodies to improve binding of effector cells and enhance activity appears more promising, as does the development of novel antibody-drug conjugates (ADCs). ADCs offer the potential to deliver potent therapies with minimal toxicity. One highly active ADC, brentuximab vedotin (SGN-35), combines an anti-CD30 monoclonal antibody and the antitubulin agent monomethyl auristatin E. Initial phase 1 studies of brentuximab vedotin showed a 52% overall response rate in relapsed HL, with minimal toxicity. This article highlights the development of anti-CD30 antibodies and ADCs for relapsed or refractory classical HL.

Novel agents for B-cell non-Hodgkin lymphoma: science and the promise

There has been tremendous insight gained in the last two decades from basic science research. New molecular targets in neoplastic cells are emerging and provide the rationale for clinical development of novel agents in non-Hodgkin lymphoma. These novel agents can be broadly categorized into two groups. The first is by immunotherapy which includes novel monoclonal antibodies and immunomodulating drugs, which takes advantage of or optimizes immune system function. The other group of drugs target small molecules that may play an important role in tumorigenesis. The mechanisms of anti-tumor activity include targeting apoptotic pathways, inhibition of proteasomes, mammalian target of rapamycin (mTOR), cyclin-dependent kinases and histone deacetylases. The purpose of this review is to focus on these novel agents and the various treatment approaches that are currently being evaluated in non-Hodgkin lymphoma.

Therapeutic potential of an anti-CD79b antibody-drug conjugate, anti-CD79b-vc-MMAE, for the treatment of non-Hodgkin lymphoma

Here we describe the generation of an antibody-drug conjugate (ADC) consisting of a humanized anti-CD79b antibody that is conjugated to monomethylauristatin E (MMAE) through engineered cysteines (THIOMABs) by a protease cleavable linker. By using flow cytometry, we detected the surface expression of CD79b in almost all non-Hodgkin lymphoma (NHL) and chronic lymphocytic leukemia patients, suggesting that anti-CD79b-vcMMAE could be widely used in these malignancies. By using NHL cell lines to simulate a patient population we discovered that a minimal cell-surface expression level of CD79b was required for in vitro activity. Within the subpopulation of cell lines above this minimal threshold, we found that sensitivity to free MMAE, mutation of cancer genes, and cell doubling time were poorly correlated with in vitro activity; however, the expression level of BCL-XL was correlated with reduced sensitivity to anti-CD79b-vcMMAE. This observation was supported by in vivo data showing that a Bcl-2 family inhibitor, ABT-263, strikingly enhanced the activity of anti-CD79b-vcMMAE. Furthermore, anti-CD79b-vcMMAE was significantly more effective than a standard-of-care regimen, R-CHOP (ie, rituximab with a single intravenous injection of 30 mg/kg cyclophosphamide, 2.475 mg/kg doxorubicin, 0.375 mg/kg vincristine, and oral dosing of 0.15 mg/kg prednisone once a day for 5 days), in 3 xenograft models of NHL. Together, these data suggest that anti-CD79b-vcMMAE could be broadly efficacious for the treatment of NHL.

Potent antibody drug conjugates for cancer therapy

Significant progress has been made in the past few years in the area of antibody drug conjugates (ADCs) for the selective delivery of cytotoxic drugs to tumors. Early work in this field incorporated clinically approved drugs and mouse monoclonal antibodies (mAbs), which had modest activities, and were generally immunogenic. The results of these studies prompted investigation that led to the identity of several key parameters that influenced activity and tolerability. These included the antigen target, the use of non-immunogenic mAb carriers, the incorporation of highly potent drugs and novel conditionally stable linker technologies, and the specific methods used to attach drugs to mAbs. As a result of these investigations, new agents with pronounced clinical activities have been developed. These include SGN-35, an ADC directed against the CD30-positive malignancies such as Hodgkin's disease and anaplastic large cell lymphoma, and trastuzumab-DM1 which has shown activity in metastatic breast carcinoma. This review details many of the technological advancements, and provides examples of promising ADCs that are currently in clinical trials.

Clinical cancer advances 2008: major research advances in cancer treatment, prevention, and screening--a report from the American Society of Clinical Oncology

A message from ASCO'S president: Nearly 40 years ago, President Richard Nixon signed the National Cancer Act, mobilizing the country's resources to make the "conquest of cancer a national crusade." That declaration led to a major investment in cancer research that has significantly improved cancer prevention, treatment, and survival. As a result, two thirds of people diagnosed with cancer today will live at least 5 years after diagnosis, compared with just half in the 1970s. In addition, there are now more than 12 million cancer survivors in the United States--up from 3 million in 1971. Scientifically, we have never been in a better position to advance cancer treatment. Basic scientific research, fueled in recent years by the tools of molecular biology, has generated unprecedented knowledge of cancer development. We now understand many of the cellular pathways that can lead to cancer. We have learned how to develop drugs that block those pathways; increasingly, we know how to personalize therapy to the unique genetics of the tumor and the patient. Yet in 2008, 1.4 million people in the United States will still be diagnosed with cancer, and more than half a million will die as a result of the disease. Some cancers remain stubbornly resistant to treatment, whereas others cannot be detected until they are in their advanced, less curable stages. Biologically, the cancer cell is notoriously wily; each time we throw an obstacle in its path, it finds an alternate route that must then be blocked. To translate our growing basic science knowledge into better treatments for patients, a new national commitment to cancer research is urgently needed. However, funding for cancer research has stagnated. The budgets of the National Institutes of Health and the National Cancer Institute have failed to keep pace with inflation, declining up to 13% in real terms since 2004. Tighter budgets reduce incentives to support high-risk research that could have the largest payoffs. The most significant clinical research is conducted increasingly overseas. In addition, talented young physicians in the United States, seeing less opportunity in the field of oncology, are choosing other specialties instead. Although greater investment in research is critical, the need for new therapies is only part of the challenge. Far too many people in the United States lack access to the treatments that already exist, leading to unnecessary suffering and death. Uninsured cancer patients are significantly more likely to die than those with insurance, racial disparities in cancer incidence and mortality remain stark, and even insured patients struggle to keep up with the rapidly rising cost of cancer therapies. As this annual American Society of Clinical Oncology report of the major cancer research advances during the last year demonstrates, we are making important progress against cancer. But sound public policies are essential to accelerate that progress. In 2009, we have an opportunity to reinvest in cancer research, and to support policies that will help ensure that every individual in the United States receives potentially life-saving cancer prevention, early detection, and treatment. Sincerely, Richard L. Schilsky, MD President American Society of Clinical Oncology.

Potent antitumor activity of the anti-CD19 auristatin antibody drug conjugate hBU12-vcMMAE against rituximab-sensitive and -resistant lymphomas

Despite major advances in the treatment of non-Hodgkin lymphoma (NHL), including the use of chemotherapeutic agents and the anti-CD20 antibody rituximab, the majority of patients eventually relapse, and salvage treatments with non-cross-resistant compounds are needed to further improve patient survival. Here, we evaluated the antitumor effects of the microtubule destabilizing agent monomethyl auristatin E (MMAE) conjugated to the humanized anti-CD19 antibody hBU12 via a protease-sensitive valine-citrulline (vc) dipeptide linker. hBU12-vcMMAE induced potent tumor cell killing against rituximab-sensitive and -resistant NHL cell lines. CD19 can form heterodimers with CD21, and high levels of CD21 were reported to interfere negatively with the activity of CD19-targeted therapeutics. However, we observed comparable internalization, intracellular trafficking, and drug release in CD21(low) and CD21(high), rituximab-sensitive and -refractory lymphomas treated with hBU12-vcMMAE. Furthermore, high rates of durable regressions in mice implanted with these tumors were observed, suggesting that both rituximab resistance and CD21 expression levels do not impact on the activity of hBU12-vcMMAE. Combined, our data suggest that hBU12-vcMMAE may represent a promising addition to the treatment options for rituximab refractory NHL and other hematologic malignancies, including acute lymphoblastic leukemia.

SGN-30: a basis for the effective treatment of CD30 positive hematopoietic malignancies

BACKGROUND

Patients with high-risk, relapsed or refractory Hodgkin lymphoma, those with systemic anaplastic large-cell lymphoma, and those with primary cutaneous CD30-positive disorders are in need of novel therapies. CD30, a common marker in these malignancies, is a reasonable immunologic target given its restricted expression in normal states. SGN-30 is a chimeric antibody targeting CD30.

OBJECTIVE

Review of data regarding SGN-30, including structure, mechanism of action, pharmacokinetics, efficacy in different patient groups, safety, and tolerability.

METHOD

The medical literature and available abstracts regarding SGN-30 are reviewed.

CONCLUSION

SGN-30 may be efficacious through multiple mechanisms of action. The most efficacious dose has yet to be determined. Given the long drug half-life, short infusions may be administered every 2 - 3 weeks. The highest response rate was seen in patients with primary cutaneous CD30-positive lymphoproliferative disease and encouraging results were seen in patients with relapsed or refractory systemic anaplastic large-cell lymphoma. Most responses in Hodgkin lymphoma were stable disease. Despite a majority of patients having had stem cell transplantation, the drug was well tolerated. There are in vivo and in vitro data that SGN-30 may be synergistic with chemotherapy.

Management of Hodgkin lymphoma in relapse after autologous stem cell transplant

Recurrence of Hodgkin lymphoma (HL) occurs in about 50% of patients after autologous stem cell transplantation (ASCT), usually within the first year, and represents a significant therapeutic challenge. The natural history of recurrent HL in this setting may range from a rapidly progressive to a more indolent course. Patients in this setting are often young, without comorbidities and able to tolerate additional therapies: expectations are often still high. The approach to treatment depends on clinical variables (time to relapse, perceived sensitivity to additional cytotoxic therapy, disease stage), prior history of radiation therapy, the availability of an HLA-identical donor, and the availability of new agents via clinical trials. Although very few of these patients can be cured, results from reported series, albeit often small and sometimes with relatively short follow-up, document that excellent disease control can be achieved with radiation, single or multiagent chemotherapy, and reduced-intensity allogeneic transplantation. The results of these approaches will be reviewed, and a treatment algorithm incorporating the use of standard or investigational agents or approaches will be discussed.