Autologous stem cell transplantation (ASCT) has yielded favourable outcomes in a high-risk cohort of patients with relapsed/refractory Hodgkin lymphoma (HL) who had previously been treated with anti-PD-1 therapy. The results were seen even among patients who were previously chemorefractory, according to US researchers.

“Historically, patients with chemorefractory R/R HL or those who require multiple salvage regimens prior to ASCT have had poor outcomes,” wrote study authors led by Dr Reid Merryman, of the Dana-Farber Cancer Institute in Boston.

ASCT has traditionally been reserved for chemosensitive patients, but other early evidence has suggested that PD-1 blockade may result in higher-than-expected response rates to cytotoxic therapy given after the immunotherapy. The authors hypothesised that anti-PD-1 therapy could sensitise patients to high-dose chemotherapy and ASCT.

They conducted a retrospective analysis of 78 relapsed/refractor HL patients who underwent ASCT after receiving an anti-PD-1 agent, either alone or in combination, as third-line or later therapy. More than half of the cohort (54%) had chemorefractory disease.

After a median follow-up period after ASCT of 19.6 months, the 18-month progression-free survival rate was 81%, and the 18-month overall survival rate was 96%.

In patients who were refractory to two consecutive systemic therapies immediately before PD-1 blockade, the 18-month PFS rate was 78%. For those who had a positive pre-ASCT PET result, the rate was 75%, and for those who had received at least four systemic therapies prior to ASCO it was 73%.

Those who did not respond to the PD-1-targeted therapy had poorer outcomes, with an 18-month PFS rate of 51%, while those who did respond had an 18-month PFS rate of 88%.

Experts called the data interesting and important, but expressed caution based on the study’s retrospective nature:

V interesting…and challenges conventional ‘wisdom’. Would be good to see validation in a prospective study https://t.co/g0bbWLZxxd

— Christopher P Fox (@DrChrisPFox) March 23, 2021

“Our study supports the use of PD-1 blockade as salvage therapy and provides initial evidence that anti-PD-1 therapy beyond the second-line setting can serve as a bridge to ASCT,” the authors concluded, agreeing that additional studies are still needed to confirm the results.

“In the meantime, based on these data, ASCT should be considered for patients with multiply R/R HL responding to anti-PD-1 therapy, even those with previously chemorefractory disease,” they said.