Affimed tries to convince with seven patients

Affimed had raised market expectations that some 20 patients’ worth of data might be forthcoming when it revealed the first cut of its Luminice-203 lymphoma trial of acimtamig, but in the event this morning’s brief update comprised a subset of just seven, from the 12 treated in the trial’s first two cohorts.

The company had cautioned in March that enrolment into these cohorts had been slower than hoped, citing Luminice-203’s staggered design, but still promised a second-quarter update from the 12 subjects in cohorts 1 and 2, plus a “certain number of patients” from cohorts 3 and 4. Given Luminice-203’s importance to Affimed, any hint of selective disclosure won’t help the company’s case.

Lumince-203 is a key test of whether acimtamig, a CD30-directed NK cell engager, can repeat the promising result seen in an MD Anderson study in Hodgkin’s lymphoma, and thus gain accelerated approval. Design differences mean that a positive result isn’t assured; MD Anderson pre-complexed acimtamig with fresh NK cells, while Luminice-203 gives acimtamig plus AB-101 NK cells with no pre-complexing, and co-administers IL-2.

Broadly similar?

Such differences don’t appear to have made Luminice-203’s first results significantly different from the academic study – at least based on the seven-patient subset Affimed toplined today.

Affimed says four of these seven have gone into complete remission, in addition to partial responses seen in two patients. The resulting 86% ORR appears broadly comparable to the 97% MD Anderson reported in 32 patients given a recommended phase 2 dose, though the CR rate, which Affimed has highlighted as a key metric, was higher in the academic trial, at 78%.

One factor that might account for any efficacy fall-off is dosing, but it’s unclear whether there are meaningful differences. The MD Anderson data concerned 100 million NK cells per kg and up to four cycles of acimtamig, whereas the first two Luminice-203 cohorts give 2 billion NK cells and up to three cycles of acimtamig; some Luminice-203 patients have only received two cycles so far.

Any numerical fall-off between the two trials aside, the response rates Affimed cited today look promising in light of the fact that this was a post-Adcetris and post-checkpoint setting. The company previously suggested that established therapies would be expected to yield CR rates of 5-34% in late-line Hodgkin’s lymphoma.

Wait for Q3

Still, Affimed is effectively asking investors to wait a little longer for more data, now saying efficacy from all 12 patients in cohorts 1 and 2 will come in the third quarter. There’s also no indication of how durable the acimtamig treatment might be, and there won’t be until the end of 2024.

Notably, cohorts 1 and 2 are fully enrolled, but the remaining five subjects are either mid-treatment cycle or are awaiting independent response assessment, Affimed told an investor call today. Curiously, all seven subjects reported on today had refractory Hodgkin’s, whereas Luminice-203 enrols patients with relapsed as well as refractory disease. Affimed wouldn't say how many Luminice-203 patients had been dosed so far.

It seems that, having promised a second-quarter Luminice-203 update, the company didn’t want to disappoint so toplined whatever data it had rather than delay again and wait until all 12 patients were evaluable. However, this strategy has raised as many questions as it has given answers. 

Affimed stock climbed 25% in early trade, before closing up just 5%; investors are in for another three months’ wait.

Acimtamig, the key data so far

Source: ASH presentation & Affimed press release.

This story has been updated.