Immutep seeks revival as cancer subgroup data reveals potential path, with many caveats

Immutep, an Australian biotech company, has reported promising new data from a subset of head and neck cancer patients, aiming to counterbalance the negative impact of an earlier trial readout. This update comes from an uncontrolled cohort of their phase 2b clinical trial, focusing on their LAG3 drug candidate, eftilagimod alfa.

In June, Immutep shared data from the controlled cohorts of the trial, which involved patients with recurrent or metastatic head and neck squamous cell carcinoma. Participants either received Keytruda alone or in combination with Immutep's eftilagimod alfa as a first-line therapy. The results showed a response rate of 32.8% in the eftilagimod group compared to 26.7% in the control group receiving only Keytruda.

A focal point of the trial was patients with high PD-L1 expression. Immutep highlighted that eftilagimod outperformed Keytruda in this subgroup, achieving a response rate of 31% versus Keytruda's 18.5%. Despite this positive outcome, the initial results led to a decline in Immutep’s stock value. The company is now attempting to recover from these losses by sharing data from an uncontrolled cohort, targeting a different subgroup of patients.

In this uncontrolled cohort, researchers enrolled patients with negative PD-L1 expression—a subgroup of head and neck cancer for which Keytruda is not approved. Approximately 20% of patients with this type of cancer exhibit negative PD-L1 expression. All 31 patients in this cohort were administered a combination of eftilagimod and Keytruda. Preliminary data from April indicated a 26.9% response rate among the first 26 patients. As of Thursday, Immutep updated this figure, reporting an improved response rate of 35.5%.

Presenting at the ESMO Virtual Plenary session, Immutep compared the response rate of their cohort with existing data from other studies. They noted that PD-L1-negative patients treated with Keytruda monotherapy had a 5% response rate, whereas patients receiving Keytruda combined with chemotherapy had a 31% response rate. These comparisons aim to contextualize eftilagimod's efficacy, though differences in study design may affect the interpretations.

The response rate achieved by eftilagimod is slightly better than that seen with Keytruda plus chemotherapy and similar to results from chemotherapy combined with the anti-EGFR antibody cetuximab. Immutep suggests there could be a market for a treatment offering the same efficacy as chemotherapy-based regimens but with fewer side effects.

However, the clarity of eftilagimod's potential benefits is still obscured due to several factors. The small size of the cohort and reliance on external controls create a degree of uncertainty. Moreover, without extensive efficacy data beyond response rates, questions remain about eftilagimod's overall impact. For instance, while cetuximab exhibited a higher response rate than Keytruda, it did not lead to improved overall survival (OS). The effect of eftilagimod on OS also remains unknown.

Following the release of the updated data, Immutep's shares experienced a significant rise, climbing 16% to $2.34 in premarket trading, up from a closing price of $2.01.