Eric L. Sievers

Brentuximab Vedotin (SGN-35) for Relapsed CD30-Positive Lymphomas

BACKGROUND Hodgkins lymphoma and anaplastic large-cell lymphoma are the two most common tumors expressing CD30. Previous attempts to target the CD30 antigen with monoclonal-based therapies have shown minimal activity. To enhance the antitumor activity of CD30-directed therapy, the antitubulin agent monomethyl auristatin E (MMAE) was attached to a CD30-specific monoclonal antibody by an enzyme-cleavable linker, producing the antibody-drug conjugate brentuximab vedotin (SGN-35). METHODS In this phase 1, open-label, multicenter dose-escalation study, we administered brentuximab vedotin (at a dose of 0.1 to 3.6 mg per kilogram of body weight) every 3 weeks to 45 patients with relapsed or refractory CD30-positive hematologic cancers, primarily Hodgkins lymphoma and anaplastic large-cell lymphoma. Patients had received a median of three previous chemotherapy regimens (range, one to seven), and 73% had undergone autologous stem-cell transplantation. RESULTS The maximum tolerated dose was 1.8 mg per kilogram, administered every 3 weeks. Objective responses, including 11 complete remissions, were observed in 17 patients. Of 12 patients who received the 1.8-mg-per-kilogram dose, 6 (50%) had an objective response. The median duration of response was at least 9.7 months. Tumor regression was observed in 36 of 42 patients who could be evaluated (86%). The most common adverse events were fatigue, pyrexia, diarrhea, nausea, neutropenia, and peripheral neuropathy. CONCLUSIONS Brentuximab vedotin induced durable objective responses and resulted in tumor regression for most patients with relapsed or refractory CD30-positive lymphomas in this phase 1 study. Treatment was associated primarily with grade 1 or 2 (mild-to-moderate) toxic effects. (Funded by Seattle Genetics; ClinicalTrials.gov number, NCT00430846.).

Results of a Pivotal Phase II Study of Brentuximab Vedotin for Patients With Relapsed or Refractory Hodgkin's Lymphoma

PURPOSE Brentuximab vedotin is an antibody-drug conjugate (ADC) that selectively delivers monomethyl auristatin E, an antimicrotubule agent, into CD30-expressing cells. In phase I studies, brentuximab vedotin demonstrated significant activity with a favorable safety profile in patients with relapsed or refractory CD30-positive lymphomas. PATIENTS AND METHODS In this multinational, open-label, phase II study, the efficacy and safety of brentuximab vedotin were evaluated in patients with relapsed or refractory Hodgkins lymphoma (HL) after autologous stem-cell transplantation (auto-SCT). Patients had histologically documented CD30-positive HL by central pathology review. A total of 102 patients were treated with brentuximab vedotin 1.8 mg/kg by intravenous infusion every 3 weeks. In the absence of disease progression or prohibitive toxicity, patients received a maximum of 16 cycles. The primary end point was the overall objective response rate (ORR) determined by an independent radiology review facility. RESULTS The ORR was 75% with complete remission (CR) in 34% of patients. The median progression-free survival time for all patients was 5.6 months, and the median duration of response for those in CR was 20.5 months. After a median observation time of more than 1.5 years, 31 patients were alive and free of documented progressive disease. The most common treatment-related adverse events were peripheral sensory neuropathy, nausea, fatigue, neutropenia, and diarrhea. CONCLUSION The ADC brentuximab vedotin was associated with manageable toxicity and induced objective responses in 75% of patients with relapsed or refractory HL after auto-SCT. Durable CRs approaching 2 years were observed, supporting study in earlier lines of therapy.

Efficacy and Safety of Gemtuzumab Ozogamicin in Patients With CD33-Positive Acute Myeloid Leukemia in First Relapse

PURPOSE Three open-label, multicenter trials were conducted to evaluate the efficacy and safety of single-agent Mylotarg (gemtuzumab ozogamicin; CMA-676; Wyeth Laboratories, Philadelphia, PA), an antibody-targeted chemotherapy agent, in patients with CD33-positive acute myeloid leukemia (AML) in untreated first relapse. PATIENTS AND METHODS The study population comprised 142 patients with AML in first relapse with no history of an antecedent hematologic disorder and a median age of 61 years. All patients received Mylotarg as a 2-hour intravenous infusion, at a dose of 9 mg/m(2), at 2-week intervals for two doses. Patients were evaluated for remission, survival, and treatment-emergent adverse events. RESULTS Thirty percent of patients treated with Mylotarg obtained remission as characterized by 5% or less blasts in the marrow, recovery of neutrophils to at least 1,500/microL, and RBC and platelet transfusion independence. Although patients treated with Mylotarg had relatively high incidences of myelosuppression, grade 3 or 4 hyperbilirubinemia (23%), and elevated hepatic transaminase levels (17%), the incidences of grade 3 or 4 mucositis (4%) and infections (28%) were relatively low. There was a low incidence of severe nausea and vomiting (11%) and no treatment-related cardiotoxicity, cerebellar toxicity, or alopecia. Many patients received Mylotarg on an outpatient basis (38% and 41% of patients for the first and second doses, respectively). Among the 142 patients, the median total duration of hospitalization was 24 days; 16% of patients required 7 days of hospitalization or less. CONCLUSION Administration of the antibody-targeted chemotherapy agent Mylotarg to patients with CD33-positive AML in first relapse induces complete remissions with what appears to be a favorable safety profile.

Brentuximab Vedotin (SGN-35) in Patients With Relapsed or Refractory Systemic Anaplastic Large-Cell Lymphoma: Results of a Phase II Study

PURPOSE Systemic anaplastic large-cell lymphoma (ALCL) is an aggressive subtype of T-cell lymphoma characterized by the uniform expression of CD30. The antibody-drug conjugate brentuximab vedotin delivers the potent antimicrotubule agent monomethylauristatin E to CD30-positive malignant cells. A phase II multicenter trial was conducted to evaluate the efficacy and safety of brentuximab vedotin in patients with relapsed or refractory systemic ALCL. PATIENTS AND METHODS Patients with systemic ALCL and recurrent disease after at least one prior therapy received brentuximab vedotin 1.8 mg/kg intravenously every 3 weeks over 30 minutes as an outpatient infusion. The primary end point of the study was overall objective response rate as assessed by independent central review. RESULTS Of 58 patients treated in the study, 50 patients (86%) achieved an objective response, 33 patients (57%) achieved a complete remission (CR), and 17 patients (29%) achieved a partial remission. The median durations of overall response and CR were 12.6 and 13.2 months, respectively. Grade 3 or 4 adverse events in ≥ 10% of patients were neutropenia (21%), thrombocytopenia (14%), and peripheral sensory neuropathy (12%). CONCLUSION Brentuximab vedotin induced objective responses in the majority of patients and CRs in more than half of patients with recurrent systemic ALCL. Targeted therapy with this CD30-directed antibody-drug conjugate may be an effective treatment for relapsed or refractory systemic ALCL and warrants further studies in front-line therapy.

Antibody-Drug Conjugates in Cancer Therapy

An antibody-drug conjugate (ADC) provides the possibility of selectively ablating cancer cells by combining the specificity of a monoclonal antibody (mAb) for a target antigen with the delivery of a highly potent cytotoxic agent. ADC target antigens are typically highly expressed on the surface of cancer cells compared to normal cells. The tumor target, the cytotoxic agent, and the manner in which the agent is attached to the antibody are key determinants of clinical activity and tolerability. Recently, several clinical trials have demonstrated that ADCs achieve higher clinical response rates than unconjugated mAbs targeting the same cell surface antigen. Brentuximab vedotin represents one such ADC that has recently been approved for the treatment of relapsed Hodgkin and systemic anaplastic large cell lymphomas--both characterized by high expression of the target antigen, CD30, on the surface of malignant cells. This review summarizes key characteristics of current, clinically active ADCs and highlights recent clinical data illustrating the benefit of antibody-targeted delivery of cytotoxic agents to cancer cells.

The discovery and development of brentuximab vedotin for use in relapsed Hodgkin lymphoma and systemic anaplastic large cell lymphoma

Progress has been made recently in developing antibody-drug conjugates (ADCs) that can selectively deliver cancer drugs to tumor cells. In principle, the idea is simple: by attaching drugs to tumor-seeking antibodies, target cells will be killed and nontarget cells will be spared. In practice, many parameters needed to be addressed to develop safe and effective ADCs, including the expression profiles of tumor versus normal tissues, the potency of the drug, the linker attaching the drug and placement of the drug on the antibody, and the pharmacokinetic and stability profiles of the resulting ADC. All these issues had been taken into account in developing brentuximab vedotin (Adcetris), an ADC that recently received accelerated approval by the US Food and Drug Administration for the treatment of relapsed Hodgkin lymphoma and systemic anaplastic large cell lymphoma (ALCL). Research is under way to extend the applications of brentuximab vedotin and to advance the field by developing other ADCs with new linker and conjugation strategies.

Final report of the efficacy and safety of gemtuzumab ozogamicin (Mylotarg) in patients with CD33-positive acute myeloid leukemia in first recurrence

In this study, the authors analyzed the efficacy and safety of gemtuzumab ozogamicin (GO) (Mylotarg®), an antibody‐targeted chemotherapy for CD33‐positive acute myeloid leukemia (AML).

Intracellular Activation of SGN-35, a Potent Anti-CD30 Antibody-Drug Conjugate

Purpose: SGN-35 is an antibody-drug conjugate (ADC) containing the potent antimitotic drug, monomethylauristatin E (MMAE), linked to the anti-CD30 monoclonal antibody, cAC10. As previously shown, SGN-35 treatment regresses and cures established Hodgkin lymphoma and anaplastic large cell lymphoma xenografts. Recently, the ADC has been shown to possess pronounced activity in clinical trials. Here, we investigate the molecular basis for the activities of SGN-35 by determining the extent of targeted intracellular drug release and retention, and bystander activities. Experimental Design: SGN-35 was prepared with 14C-labeled MMAE. Intracellular ADC activation on CD30+ and negative cell lines was determined using a combination of radiometric and liquid chromatograhpy/mass spectrometry-based assays. The bystander activity of SGN-35 was determined using mixed tumor cell cultures consisting of CD30+ and CD30− lines. Results: SGN-35 treatment of CD30+ cells leads to efficient intracellular release of chemically unmodified MMAE, with intracellular concentrations of MMAE in the range of 500 nmol/L. This was due to specific ADC binding, uptake, MMAE retention, and receptor recycling or resynthesis. MMAE accounts for the total detectable released drug from CD30+ cells, and has a half-life of retention of 15 to 20 h. Cytotoxicity studies with mixtures of CD30+ and CD30− cell lines indicated that diffusible released MMAE from CD30+ cells was able to kill cocultivated CD30− cells. Conclusions: MMAE is efficiently released from SGN-35 within CD30+ cancer cells and, due to its membrane permeability, is able to exert cytotoxic activity on bystander cells. This provides mechanistic insight into the pronounced preclinical and clinical antitumor activities observed with SGN-35. Clin Cancer Res; 16(3); 888–97

Brentuximab vedotin as consolidation therapy after autologous stem-cell transplantation in patients with Hodgkin's lymphoma at risk of relapse or progression (AETHERA): a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND High-dose therapy followed by autologous stem-cell transplantation is standard of care for patients with relapsed or primary refractory Hodgkins lymphoma. Roughly 50% of patients might be cured after autologous stem-cell transplantation; however, most patients with unfavourable risk factors progress after transplantation. We aimed to assess whether brentuximab vedotin improves progression-free survival when given as early consolidation after autologous stem-cell transplantation. METHODS We did this randomised, double-blind, placebo-controlled, phase 3 trial at 78 sites in North America and Europe. Patients with unfavourable-risk relapsed or primary refractory classic Hodgkins lymphoma who had undergone autologous stem-cell transplantation were randomly assigned, by fixed-block randomisation with a computer-generated random number sequence, to receive 16 cycles of 1·8 mg/kg brentuximab vedotin or placebo intravenously every 3 weeks, starting 30-45 days after transplantation. Randomisation was stratified by best clinical response after completion of salvage chemotherapy (complete response vs partial response vs stable disease) and primary refractory Hodgkins lymphoma versus relapsed disease less than 12 months after completion of frontline therapy versus relapse 12 months or more after treatment completion. Patients and study investigators were masked to treatment assignment. The primary endpoint was progression-free survival by independent review, defined as the time from randomisation to the first documentation of tumour progression or death. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT01100502. FINDINGS Between April 6, 2010, and Sept 21, 2012, we randomly assigned 329 patients to the brentuximab vedotin group (n=165) or the placebo group (n=164). Progression-free survival by independent review was significantly improved in patients in the brentuximab vedotin group compared with those in the placebo group (hazard ratio [HR] 0·57, 95% CI 0·40-0·81; p=0·0013). Median progression-free survival by independent review was 42·9 months (95% CI 30·4-42·9) for patients in the brentuximab vedotin group compared with 24·1 months (11·5-not estimable) for those in the placebo group. We recorded consistent benefit (HR <1) of brentuximab vedotin consolidation across subgroups. The most frequent adverse events in the brentuximab vedotin group were peripheral sensory neuropathy (94 [56%] of 167 patients vs 25 [16%] of 160 patients in the placebo group) and neutropenia (58 [35%] vs 19 [12%] patients). At time of analysis, 28 (17%) of 167 patients had died in the brentuximab vedotin group compared with 25 (16%) of 160 patients in the placebo group. INTERPRETATION Early consolidation with brentuximab vedotin after autologous stem-cell transplantation improved progression-free survival in patients with Hodgkins lymphoma with risk factors for relapse or progression after transplantation. This treatment provides an important therapeutic option for patients undergoing autologous stem-cell transplantation. FUNDING Seattle Genetics and Takeda Pharmaceuticals International.

A Phase II study of SGN‐30 (anti‐CD30 mAb) in Hodgkin lymphoma or systemic anaplastic large cell lymphoma

SGN‐30, a chimeric anti‐CD30 monoclonal antibody, has demonstrated potent preclinical antitumour activity in both Hodgkin lymphoma (HL) and anaplastic large cell lymphoma (ALCL). We conducted an open‐label, Phase II study to determine the safety and objective response rate of SGN‐30 in 79 patients with refractory/recurrent HL (n = 38) or systemic ALCL (n = 41). Each course of SGN‐30 comprised 6 weekly intravenous infusions, followed by a 2‐week treatment‐free period. Patients had received a median of 3 (range 1–5) prior regimens of chemotherapy or systemic therapy. The initial 40 patients received 6 mg/kg weekly; the latter 39 patients received 12 mg/kg weekly. In the ALCL group, two patients achieved a complete response and five additional patients achieved a partial response, with response durations ranging from 27 to 1460+ d. No objective responses were observed in the HL group; however, 11 patients (29%) had stable disease (duration 62–242 days). Although adverse events were common, most were mild or moderate, and no specific pattern of adverse events was observed in either disease group. These results demonstrate that weekly administration of SGN‐30 is safe, with modest clinical activity in patients with ALCL.