PLUS THERAPEUTICS, INC. Q1 FY2023 earnings call

• Clinical and regulatory progress: GBM Phase 2b trial actively enrolling with goal to complete enrollment of 31 patients by end 2024; Phase 1 GBM dose escalation trial has enrolled 27 patients; LM Phase 1 Part A completed with no dose limiting toxicities observed; plan to submit updated IND for pediatric brain cancer trial; working on supply chain expansion and commercial planning; ongoing dialogue with FDA on RNL BAM technology designation.
• Financials: Benefits from grant awards of $3 million from NIH and $17.6 million from CPRIT; has access to at least $49 million via ATM and equity line of credit.

As of March 31, 2023, cash and cash equivalents were $12.7 million compared to $18.1 million as of December 31, 2022. Grant revenue of $506,000 was recognized in Q1 2023 from CPRIT for funding part of the LM clinical program. Total operating expenses were $5.2 million in Q1 2023 vs. $3.9 million in the prior year, driven by a $750,000 licensed payment and increased clinical expenses. Net loss for Q1 2023 was $4.8 million or $0.14 per share.

• Intend to publish Phase 1 GBM data in peer-reviewed journal in 2023.
• Plan to present safety and efficacy data from GBM and LM trials in second half of 2023.
• Intend to initiate LM Phase 1 Part B in second half of 2023 after FDA Type C meeting.
• Aim to complete GBM Phase 2b enrollment by end 2024.
• Plan to initiate pediatric brain cancer trial in 2023.
• Intend to determine RNL BAM technology regulatory designation.
• Plan to complete preclinical drug combination studies and submit grant applications.

Q: Radiopharmaceuticals seems to be in the spotlight with notable commercial success in imaging and therapy and prostate cancer. Any comments on the evolving development landscape for radiopharmaceuticals in brain cancer? And as a follow up to that, can you remind us of the potential benefits of your approach versus molecularly targeted and/or systemic approaches in the context of brain cancer?

A: Norman LaFrance discussed that radiopharmaceuticals like PSMA and serotonin products have their own requirements, but our approach leverages convection enhanced delivery catheters to directly deliver the isotope to the tumor, allowing it to stay localized, differentiating from systemic therapies that face blood brain barrier challenges.

Q: It's great to see the addition of Northwestern Memorial Hospital as a trial site. Can you provide any color on how easy or challenging it is to onboard new sites? And then do you have a sense of how that could translate to potential commercial success down the line? And what type of sites do you imagine these assets could be administered at e.g. only top centers versus any hospital with a working radio pharmacy?

A: Norman LaFrance said getting sites on board is straightforward with well-defined protocols involving neuro oncology, neurosurgery, and nuclear medicine collaboration; sites are evolving post-COVID, and the assets could be administered at elite sites as well as larger commercial hospitals with working radio pharmacies.

Q: Based on your updates, you're obviously keeping pace with enrollment. Can you comment on investigator and patient enthusiasm that you've encountered?

A: Norman LaFrance mentioned investigators are enthusiastic, citing examples like a Hopkins neuro oncologist being motivated to get involved, and patients expressing gratitude for the opportunity and positive experiences like a GBM patient returning to playing softball after treatment.

Q: My first question is on the GBM side. I know you mentioned that the study for treating larger tumors has been going well, and you will be able to test the higher doses of RN. I was wondering whether it's something that you consider roll into your potential future Phase 3 in GBM, or would you keep the two separate, like the regular dose and higher dose?

A: Marc Hedrick said it depends on the data from analyzing cohorts 7 and 8, and they will continue tweaking delivery parameters as they go forward.

Q: My second question is on the LM study. You mentioned that you were testing in particular looking to with melanoma patients, that's one way why melanoma is and if there's something you see or you think, in other cases, you that makes it particularly well suited for [end treatment] [ph]?

A: Norman LaFrance said LM can be caused by various tumors, but melanoma is an example of a disease indication with potential for combination therapy, as melanoma has shown systemic therapeutic effects with immunotherapy, and there's an opportunity for combination treatment with their product.

Q: My final question is on the upcoming pediatric study, just wondering whether you had to make specific adjustments to your delivery method? Because I know the uses the connection catheters, is it going to be any different than what you've done so far with adults?

A: Norman LaFrance said the approach will be the same, with pediatric neurologists accustomed to using catheters for epilepsy evaluations, and while larger volumes in ependymoma may require evaluation, the basic delivery method remains the same.

Q: My question is on the CPRIT grant. Are there any restrictions to where you can look at your sites or any other requirements that you guys have when you're running these clinical trials?

A: Marc Hedrick said there are no restrictions on where clinical sites can be, though there are some restrictions around having sites in Texas and related employee/office spaces.