IMS 2025 | Results from part one of the Phase I/II DREAMM-20 trial of belantamab in RRMM

So at this IMS meeting I had the privilege of presenting the first look of part one of the DREAMM-20, a study of belantamab in patients with relapsed/refractory multiple myeloma. Now to set the scene belantamab is not the same as belantamab mafodotin. It is a monoclonal antibody that’s naked targeting BCMA and unlike belantamab mafodotin it is not conjugated to the monomethyl auristatin F that is thought to correlate with corneal toxicity. So in the DREAMM-20 study we enrolled patients who were triple class exposed and had at least three prior lines of therapy. Prior BCMA target therapies were allowed. Belantamab was given intravenously on days 1 and 15 every 28 days until disease progression in escalating doses of 300 mg, 900 mg and 2000 mg and treatment was until disease progression. 18 patients were enrolled, 6 in each of the 3 dose escalations and these patients were heavily pre-treated with a median of four and up to 18 prior lines of therapy. So what did we see? Belantamab from an efficacy point of view is very well tolerated. The most common adverse event was infusion reaction that occurred in only four out of the 18 patients, so 22%, but all these were mild. They were easily manageable by paracetamol and did not recur again upon re-challenge. Haematological toxicities were low, neutropenia, anaemia and thrombocytopenia only occurred in a handful of patients and there was no significant signal at all for infections. What about corneal adverse events that everyone seems to be talking about? Well interestingly we saw two patients with grade two or more corneal adverse events but neither of these patients were attributed to belantamab itself. And in fact, the corneal adverse events improved spontaneously and did not recur upon re-challenge with the same dose of belantamab. And all the other lower grade corneal findings seemed to be reflective of the baseline corneal abnormalities that we see in elderly patients as opposed to treatment-related toxicity. In terms of efficacy, we saw responses in 5 out of 18 patients giving an overall response rate of 28% with a VGPR in 3 patients. But what was really striking was the durability of response. Four out of these five patients responded for over one year, including one patient who was still responding more than one and a half years on. There was one patient who stopped treatment after six months having achieved a VGPR and that was out of her own choice. And so just to summarise, even without the monomethyl auristatin F payload, belantamab still demonstrated meaningful efficacy in multiple myeloma and with a very favourable safety profile, in particular, no treatment-related severe ocular toxicity and no significant signal for haematological toxicities or infections. The DREAMM-20 is currently underway, exploring the combination of belantamab with belantamab mafodotin, leveraging on the clinical activity of belantamab to allow us to perhaps use a lower and less frequent dose of mafodotin with the overall aim of improving outcome and minimizing the corneal toxicity. Now, I think it’s really early days, but it is exciting, and I think it does open up new possibilities for BCMA target therapies in multiple myeloma.

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