Updated 3-year results for two brentuximab vedotin (Adcetris™) pivotal phase II trials in patients with relapsed/refractory Hodgkin lymphoma and systemic anaplastic large cell lymphoma both showed extended survival for these heavily pre-treated patients.

The studies were presented at the 55th American Society of Hematology meeting, held in New Orleans, LA, December 7-10, 2013.

For patients with relapsed or refractory Hodgkin lymphoma (HL), the standard of care has been salvage chemotherapy followed by auto-SCT, which induces long-term remission in approximately 50% of patients. For patients who experience relapse or progressive HL within 1 year of auto-SCT, prognosis has been poor, with a median survival of approximately 1.2 years.

In systemic anaplastic large cell lymphoma (sALCL), approximately 40-65% of patients develop recurrent disease after frontline treatment. For these patients, who have a median overall survival of 7 months, there has been no defined standard of care.

“Clearly both these patient populations represent an urgent unmet medical need,” said Prof. Anton Hagenbeck, from the Academic Medical Centre, Amsterdam.

Brentuximab vedotin is an antibody-drug conjugate (ADC) directed to CD30, a defining marker of classical HL and sALCL. The drug comprises an anti-CD30 monoclonal antibody attached by a protease-cleavable linker to a microtubule disrupting agent, monomethyl auristatin E (MMAE).

The proprietary technology employs a linker system designed to be stable in the blood stream, but to release MMAE upon internalization into CD30 expressing tumor cells.

Prof. Hagenbeck explains:

To the cancer cells this conjugate represents a wolf in sheep’s clothing. Key to success has been the strengthened linker system that prevents the complex from breaking down outside the cell resulting in less systemic toxicity and high efficacy.”

Brentuximab vedotin, the only antibody-drug conjugate (ADC) currently on the market, received accelerated approval from the FDA in August 2011, and conditional marketing authorisation from the European Commission in October 2012.

In the first study1 (abstract number 4382), Ajay Gopal from the Fred Hutchinson Cancer Research Center, Seattle, WA and colleagues set out to determine the efficacy and safety of brentuximab vedotin in 102 patients (median age 31 years) with relapsed or refractory HL following auto-SCT. The patients, received 1.8 mg/kg brentuximab vedotin every 3 weeks as 30-minute outpatient infusions for up to 16 cycles.

Results show that the median overall survival for patients receiving brentuximab vedotin was 40.5 months (95% CI: 28.7, [range, 1.8 to 48.3+ months]. This result can be compared to a retrospective multicenter series of patients relapsing after auto-SCT, which showed a median overall survival of 2.4 years (Leuk. Lymphoma 2013, 54:2531-2533).

Additionally, the estimated 3-year survival for the current study was 54% (95% CI:44-64%), and at a median of 32.7 months (range 1.8 to 48.3 months) since first dose brentuximab vedotin 50% (51 of 102) patients were alive.

Furthermore, 18 patients remained in remission according to the investigator review and 14 patients according to central independent review.

“It could even be that these patients are cured because we know in this high-risk group responders are likely to have relapsed by 2 years,” said Hagenbeck.

The most common adverse events were peripheral sensory neuropathy (47%), fatigue (46%) nausea (42%), upper respiratory tract infections (37%) and diarrhea (36%).

In the second study2 (abstract 1809), Barbara Pro, from the Fox Chase Cancer Center, Philadelphia, PA and colleagues, set out to determine the efficacy and safety of brentuximab vedotin in 58 patients (median age 52 years) with relapsed or refractory sALCL. Patients received 1.8 mg/kg IV every 21 days administered over 30 minutes in outpatients.

As previously reported, the overall response rate was 86% (50 of 58 patients) and the complete response rate was 59% (34 of 58 patients) (CI 75-94). With a median observation time from first dose of 33.4 months, the current analysis found the median duration of objective response for all patients was 13.2 months; and for patients obtaining a complete response the median duration of response was 26.3 months.

Of the 34 patients who achieved a complete response, 16 (47%) remained in remission at the time of analysis. The estimated 3-year survival rate was 63% (95% CI:51% -76%), while the median overall survival for patients obtaining a complete response has yet to be reached.

Three phase III trials of brentuximab vedotin are currently ongoing, in frontline HL, frontline mature T-cell lymphoma, and high risk post-transplant HL patients.