Immutep has spotted a potential niche for its LAG3 drug candidate, reporting phase 2b data in a subset of head and neck cancer patients to partly wipe away the stain left by an earlier readout.
The Australian biotech reported data from the controlled cohorts of the trial in June. People with recurrent or metastatic head and neck squamous cell carcinoma received either Keytruda as a single agent or the checkpoint inhibitor in combination with Immutep’s LAG3 drug candidate eftilagimod alfa as a first-line therapy. The response rate was 32.8% in the eftilagimod cohort and 26.7% in the control arm.
Immutep picked out data in patients with high PD-L1 expression as a positive, stating that eftilagimod beat Keytruda’s response rate by 31% to 18.5% in the subgroup, but investors still sent the stock down. Now, the biotech is trying to regain some of the lost ground by sharing data from an uncontrolled cohort.
Investigators enrolled patients with negative PD-L1 expression in the uncontrolled cohort. One-fifth of patients with the cancer type have negative PD-L1 expression, and Keytruda isn’t approved in the subpopulation, Immutep said.
All 31 patients in the uncontrolled cohort received eftilagimod and Keytruda in combination. Immutep reported a preliminary 26.9% response rate in the first 26 patients enrolled in the cohort in April. The biotech updated the data Thursday, telling investors that the response rate now stands at 35.5%.
Presenting at the ESMO Virtual Plenary session, Immutep compared (PDF) the response rate to the 5% seen in PD-L1-negative patients who received Keytruda as a monotherapy and the 31% seen in people who took the checkpoint inhibitor on top of chemotherapy. The figures come from other studies and, as such, may give a misleading impression of how eftilagimod shapes up against existing treatment options.
The response rate is barely better than the Keytruda-chemo result and in line with that seen in patients who take chemotherapy in combination with the anti-EGFR antibody cetuximab. However, there may be a market for a treatment that provides the same efficacy as chemotherapy-based regimens without their side effects.
It is unclear from Immutep’s data whether eftilagimod is such a treatment. As well as the uncertainty created by the relatively small cohort and reliance on external controls, the lack of efficacy data beyond response rates leaves unanswered questions. Cetuximab had a higher response rate than Keytruda, but that failed to translate into improved overall survival (OS). It is unclear what effect eftilagimod has on OS.
Immutep's shares rose 16% to $2.34 in premarket trading Friday, compared to a closing price $2.01.