BioAtla, Inc. Q1 FY2024 earnings call

Bruce Mackle introduced the BioAtla team. Jay Short discussed progress in clinical programs, including positive data for CAB-ROR2-ADC in head and neck cancer with 38% response and 86% disease control rate, plans to meet with FDA for registrational trial guidance. Eric Sievers talked about the CAB CTLA-4 IO antibody Phase 1/2 trial progressing well with manageable safety, Sheri Lydick highlighted market opportunities for CTLA-4 and ROR2 ADC assets, and Richard Waldron reviewed first quarter financials with R&D expenses down, net loss lower, and cash burn expectations.

Expect operating cash burn of approximately $20 million for Q2 2024 and continuing to decrease in H2 2024. Plan to meet with FDA in H2 2024 for guidance on registrational trial for CAB-ROR2-ADC. On track to clear DLT observation period with 1 gram dose of CAB CTLA-4 IO antibody later in Q2 2024.

Uncertainties in clinical trial results and timing. Regulatory approval uncertainties. Cash burn and sufficiency of funds to support operations.

Q: Elaborate on duration of confirmed responses with ROR2 ADC in head and neck A: Thanks, Brian. I’ll let Eric take a crack at this one. Thank you. Eric Sievers: Thanks, Brian. So we definitely need further follow-up to estimate our duration of response, but I will refer you to Slide 29 of our updated corporate deck, the swimmers plot gives you a sense of the confirmed responses and addresses the question you asked, particularly the patients that were treated at the every other week dosing. I will note that those patients were dosed first and then after completing that effort, we then went on to employ the days one and aid [ph] regimen. So we have a bit longer follow-up for the patients in blue on Slide 29. Jay Short: And I’ll just add there are eight patients still on treatment and that are ongoing of which two have responses that could confirm, and there’s also two with decreasing tumor volume.

Q: Provide color on median follow-up for AXL ADC and recruiting plans A: Jay Short: Thank you. Yes. Because we’ve completed the dosing that we intended for the first portion of the potentially registrational trial, our main goal here is to achieve multiple scans for each of those patients, which we think should readily occur in the second half of this year. And so our current thinking, assuming we got encouraging – continue to get encouraging data that we would have an opportunity to start that next portion of the – remaining portion of the registrational trial in late 2024.

Q: Feedback from physicians on ROR2 ADC data, competitive landscape A: Eric Sievers: Thanks, Kaveri. It’s Eric answering. So, first, your question about the feedback we’ve gotten from physicians, I’ll just give you some anecdotes. We received a call from the PI at USC indicating how pleased he was to report a complete response, and that’s now confirmed and enabling the patient to go back to work. And that’s a patient that we review in our corporate deck. We were also pleased to hear from Memorial Sloan Kettering, where two of the investigators spoke about several patients on treatment, particularly emphasizing the tolerability and the rapidity of response. They felt that it really was serving an unmet need in this second, third and fourth line, head and neck cancer, which is exceptionally challenging, and so many patients having clinical progression as they’re getting these therapies. And then you asked the question about did prior treatment with one of the other auristatin based ADCs. When I looked through the prior treatments, all patients had received a PD-1 blocking agent. Many received either a platinum or – and/or a taxane regimen. I didn’t see any anecdotes of people that had received prior ADCs, but it’s certainly an interesting question with regard to the studies that are ongoing. Sheri Lydick: Yes. And Kaveri, this is Sheri. I can – if I could take the question on the competitive landscape. Obviously, within the existing competitive landscape, there remains a profound unmet need and patients who fail frontline options, as you know, in second line cetuximab is often used with an ORR 13%. So we think – within the existing therapeutic landscape that there remains an unmet need. And even if you look at the future competitive landscape, we have a different mechanism of action than those that are in development. And we think that the profile that’s emerging in this very heavily pre-treated patient population, really, really provides the opportunity for us to benefit patients in the second line setting within the existing as well as the future competitive landscape.

Q: Dosing regimens for ROR2 and CTLA-4, HPV correlation, CTLA-4 data A: Jay Short: I’ll just start off by saying and I’ll let Eric finish this, but I just want to say, I’ll remind us all that we did use the 2Q3W in Phase 1, so it’s not that new. It’s certainly one we’ve looked at. But with respect to 2Q3W, certain characteristics, I’ll let Eric add to this. Eric Sievers: Sure. Thanks, Jay. So I’ll emphasize that both of the regimens, I think, are exceptionally well tolerated. I’ll refer everyone to Slide 35 of our corporate deck, where we’ve summarized the every other week dosing the 2Q3W, which is days one and eight of a three week cycle, and then for melanoma as well. And in here, we’re having very few instances of related AEs leading to treatment discontinuation. And so tolerability is excellent with both regimens. We are seeing in the head and neck data in particular, I think you can see from the spider plot on Slide 28 just a sense that we get more rapid disease control in the red, which is the more intensive regimen than the blue. And it is interesting with the blue patients, they did have longer exposure because we did those patients first. There are quite a few patients. There are the two instances of patients that are at many, many weeks of therapy, one passing 35 weeks and one passing 45 weeks on study. So I think both regimens well tolerated and the PK/PD, no surprises there. So looking good. Eric Sievers: Yes, it’s a great question, Arthur. We have not seen a correlation with HPV expression. It’s something that we’re going to continue to look at very closely. Those patients receive therapy that’s a little bit different. There’s some recent data suggesting they can deescalate the aggressive early therapy. And so we’ve been guided by our investigators to think of them as a little bit different than the HPV negative population. But right now, not seeing any obvious correlations. And I’ll just add that we’re also not seeing obvious correlations with the ROR2 expression, because that’s often a question that people ask us, and so we’re not needing a companion diagnostic at this time.