Post-autologous transplant maintenance therapies in lymphoma: current state and future directions

Disease relapse following high-dose chemotherapy and autologous stem cell transplant (ASCT) remains the principal cause of mortality in patients with relapsed or refractory lymphomas. In an effort to prevent post-ASCT relapse, a number of studies have evaluated the role of maintenance therapy with varying success. In diffuse large B-cell lymphoma, studies evaluating maintenance rituximab (MR) following ASCT failed to demonstrate improved outcomes. In follicular lymphoma, MR was associated with an improvement in PFS; however, no overall survival (OS) benefit was noted. Emerging data evaluating MR in mantle cell lymphoma (MCL) have demonstrated improvements in PFS, although a consistent improvement in OS has yet to be demonstrated. Given the aggressive and incurable nature of MCL, it is prudent for practitioners to weigh the risks and benefits of MR in the post-ASCT setting. Similarly, post-ASCT maintenance therapy with brentuximab vedotin in Hodgkin lymphoma, has led to improved PFS and may be considered in those with a high risk of relapse. Ongoing clinical studies evaluating a multitude of novel maintenance therapies are crucial to the efforts of further defining and optimizing the role of post-transplant maintenance therapy in lymphoma.

Brentuximab vedotin

Brentuximab vedotin (SGN-35; Adcetris®) is an anti-CD30 antibody conjugated via a protease-cleavable linker to the potent anti-microtubule agent monomethyl auristatin E (MMAE). Following binding to CD30, brentuximab vedotin is rapidly internalized and transported to lysosomes where MMAE is released and binds to tubulin, leading to cell cycle arrest and apoptosis. Several trials have shown durable antitumor activity with a manageable safety profile in patients with relapsed/refractory Hodgkin lymphoma, systemic anaplastic large cell lymphoma, or primary cutaneous CD30-positive lymphoproliferative disorders. Peripheral sensory neuropathy is a significant adverse event associated with brentuximab vedotin administration. Neuropathy symptoms are cumulative and dose-related. Multiple ongoing trials are currently evaluating brentuximab vedotin alone or in combination with other agents in relapsed/refractory patients, as well as patients with newly diagnosed disease.

Brentuximab vedotin: a new age in the treatment of Hodgkin lymphoma and anaplastic large cell lymphoma

OBJECTIVE

To review the clinical trial data, pharmacology, pharmacokinetics, and adverse effects of brentuximab vedotin.

DATA SOURCES

A literature search was performed using MEDLINE and PubMed (both 1966-October 2011), as well as the American Society of Hematology abstracts (2000-January 2012), using the primary search terms brentuximab vedotin, SGN-35, Hodgkin lymphoma (HL), and anaplastic large cell lymphoma (ALCL).

STUDY SELECTION AND DATA EXTRACTION

Published and ongoing clinical studies and abstracts in the English language that detail the pharmacology, pharmacokinetics, safety, and clinical efficacy of brentuximab vedotin in the treatment of HL and ALCL were included in this review.

DATA SYNTHESIS

Brentuximab vedotin is an antibody drug conjugate that combines the anti-CD30 antibody, cAC10, with the synthetic tubulin disrupting agent monomethyl auristatin E. A Phase 1 trial in patients with relapsed and refractory HL or systemic ALCL supported a dose of 1.8 mg/kg every 3 weeks. The drug was well tolerated, with the majority of adverse reactions being grade 1 or 2 in severity. Common toxicities included fatigue, pyrexia, diarrhea, nausea, neutropenia, and peripheral neuropathy. Phase 2 studies in the same patient populations illustrated objective response rates of 73-86% with an acceptable toxicity profile. Based on results of these Phase 2 trials, the Food and Drug Administration granted approval of brentuximab vedotin in August 2011 for the treatment of relapsed and refractory HL or ALCL.

CONCLUSIONS

Phase 1 and 2 clinical trial data indicate that brentuximab vedotin is efficacious and safe in patients with relapsed and refractory CD30-positive lymphomas. This agent is being investigated in combination with chemotherapy to further elucidate its role in lymphoma therapy.

A phase I weekly dosing study of brentuximab vedotin in patients with relapsed/refractory CD30-positive hematologic malignancies

PURPOSE

The antibody-drug conjugate (ADC) brentuximab vedotin comprises a CD30-directed antibody covalently attached to the potent antimicrotubule agent monomethyl auristatin E (MMAE) via a protease-cleavable linker. This study explored the safety, maximum-tolerated dose (MTD), and activity of weekly dosing of brentuximab vedotin in patients with relapsed or refractory CD30-positive hematologic malignancies.

EXPERIMENTAL DESIGN

In this phase I dose-escalation study, brentuximab vedotin was administered intravenously on Days 1, 8, and 15, of each 28-day cycle at doses ranging from 0.4 to 1.4 mg/kg. Forty-four patients were enrolled: 38 with Hodgkin lymphoma, five with systemic anaplastic large cell lymphoma, and one with peripheral T-cell lymphoma not otherwise specified. Doses were escalated in increments of 0.2 mg/kg until dose-limiting toxicity (DLT) was observed. Patients were monitored for antitherapeutic antibodies and pharmacokinetic parameters. Antitumor assessments were carried out every two cycles.

RESULTS

The MTD was 1.2 mg/kg. The most common adverse events were peripheral sensory neuropathy, fatigue, nausea, diarrhea, arthralgia, and pyrexia; and the majority of events were mild to moderate in severity. Tumor regression occurred in 85% of patients and the overall objective response rate was 59% (n = 24), with 34% (n = 14) complete remissions. The median duration of response was not reached at a median follow-up of 45 weeks on study.

CONCLUSIONS

Weekly administration of brentuximab vedotin resulted in tumor regression and durable remissions in patients with CD30-positive malignancies. This ADC was associated with manageable toxicity, including peripheral neuropathy. Further study in CD30-positive malignancies is warranted.