Conference Coverage

Applying ECHELON-2 results to clinical practice


 

EXPERT ANALYSIS FROM TCLF 2019

– Results from the ECHELON-2 trial led to the U.S. approval of brentuximab vedotin (BV) in combination with cyclophosphamide, doxorubicin, and prednisone (CHP), but there are still questions about how to apply the trial results to practice.

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At the annual T-cell Lymphoma Forum, trial investigators and other physicians debated the best use of this combination.

BV-CHP is approved to treat patients with previously untreated systemic anaplastic large-cell lymphoma (sALCL) or other CD30-expressing peripheral T-cell lymphomas (PTCLs), including angioimmunoblastic T-cell lymphoma (AITL) and PTCL not otherwise specified (NOS).

Patients who received BV-CHP in ECHELON-2 had superior progression-free survival (PFS) and overall survival (OS) compared to patients who received cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP).

These results were initially presented at the 2018 annual meeting of the American Society of Hematology and simultaneously published in The Lancet (2019 Jan 19;393[10168]:229-40).

ECHELON-2 investigator Owen O’Connor, MD, PhD, of Columbia University Medical Center in New York, also presented details on the trial at the T-cell Lymphoma Forum. His presentation was followed by a discussion with meeting attendees about applying the trial results to clinical practice.

CD30 expression

One of the issues discussed was the importance of CD30 expression in deciding which patients should receive BV.

For a patient to be eligible for ECHELON-2, the diagnostic biopsy had to show at least 10% of the neoplastic cells were CD30-positive. However, the Food and Drug Administration (FDA) has not made a similar requirement for prescribing BV. PTCL patients with any level of CD30 expression are eligible for treatment with BV-CHP, according to the FDA.

“[I]t’s still a matter of great debate and controversy as to whether we have good enough data to suggest that there’s a threshold effect with regard to the expression of CD30 and responsiveness or sensitivity to brentuximab vedotin,” Dr. O’Connor said.

“This has been an issue from the very first day with this drug, which is, ‘Just how much CD30 do you need to get a response?’ I can’t speak on behalf of the FDA, but I think they are not absolutely convinced that there’s a threshold. They take [CD30-] positive as ‘good enough’ across the board.”

“The FDA has said, ‘The data we’ve seen says there’s a lot of heterogeneity [with biopsies].’ You may do a biopsy and find 30% [of cells are CD30-positive], and you may do another biopsy [in the same patient] and find less than 10%. I don’t think the regulatory agencies are convinced that a single biopsy looking at CD30 ... is representative of the entire tumor burden.”

Andrei Shustov, MD, an ECHELON-2 investigator from the University of Washington in Seattle, questioned whether CD30 expression should be considered when deciding on the use of BV in PTCL.

“Is CD30 staining relevant at all, or should we default back to studies, say, in colon cancer where we didn’t even care about EGFR because we might be missing it by current techniques?” Dr. Shustov asked. “Should we even worry about CD30 expression ... because we cannot reliably detect low levels of CD30?”

Some attendees echoed this sentiment, questioning the utility of assessing CD30 expression. Other attendees said they would defer to the trial data and only treat patients with BV-CHP if they had at least 10% CD30.

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