Naptumomab is a cancer drug consisting of a superantigen and an antibody part targeting the tumour antigen 5T4. NeoTX is sponsoring two trials with this candidate; the other one is in breast cancer with docetaxel (chemotherapy). New results have been published in the trial combining naptumomab with durvalumab, a PD-L1 checkpoint inhibitor.  The trial is a standard 3+3 dose expansion study designed to find a recommended phase II dose (RP2D), which was found to be 10 micrograms per kilo. 59 patients were enrolled with various types of cancers (many of them aggressive and difficult to treat) with a median of three prior lines of treatment. Patients were pre-treated with obinutuzumab to prevent the formation of antibodies against naptumomab. The most common adverse event was infusion-related reactions, with 85% reporting grade 1-2 (not severe), and 10% grade 3. 95% of these events occurred early and were rapidly reversed. 7% of patients discontinued treatment due to toxicities at doses above the RP2D, while no patients discontinued at RP2D. 23 patients were treated with the recommended phase II dose.

There were some promising anti-tumour results. Two patients had a complete response (no measurable tumours), two had a partial response and four had stable disease, which is equivalent to a disease control rate of 19% based on 42 evaluable patients. These results are difficult to judge given the challenging population recruited and different doses administered. Further evaluation in earlier lines of treatment with a patient population more likely to respond is warranted. Another positive conclusion from the study is the fact that neutralisation with binutuzumab appears to have worked. We do not change our valuation of the project based on these results. Our Base Case of Active Biotech remains SEK3.