Rain Enhancement Technologies Holdco, Inc. Q1 FY2022 earnings call

• Milademetan program progress: The Phase III MANTRA study for milademetan in liposarcoma is progressing well, with enrollment expected to complete by the end of 2023 and top line pivotal Phase III data anticipated in the first half of 2023 (earlier than previously guided). The Phase II tumor-agnostic MANTRA-2 study is proceeding as planned, with an interim data readout expected in the fourth quarter of 2022 on approximately the first 10 patients. Two additional studies, MANTRA-3 in Merkel cell carcinoma and MANTRA-4 combining milademetan with atezolizumab, are planned to start in the fourth quarter of 2022.
• Clinical trial details: The MANTRA study is global, with enrollment across the U.S., Europe, and Asia. The MANTRA-2 basket trial will evaluate milademetan in 65 patients with solid tumors exhibiting high MDM2 gene amplification. The MANTRA-3 study will focus on Merkel cell carcinoma patients resistant or refractory to checkpoint inhibitor therapy. The MANTRA-4 study will assess the combination of milademetan and atezolizumab in p53 wild-type advanced solid tumors with CDKN2A loss.
• Scientific updates: Rain presented data at the AACR Annual Meeting on tumors harboring high-level MDM2 gene amplification. Preclinical data on milademetan in Merkel cell carcinoma PDX models was presented, and an abstract on the MANTRA-4 study will be presented at ASCO.

For the first quarter of 2022, Rain Therapeutics reported a net loss of $17.4 million compared to a net loss of $6.8 million in the first quarter of 2021. Research and development expenses were $13.6 million in Q1 2022 versus $5.3 million in Q1 2021. General and administrative expenses were $3.9 million in Q1 2022 compared to $1.5 million in Q1 2021. As of March 31, 2022, Rain had $123.2 million in cash, cash equivalents, and short-term investments.

• Anticipate completion of enrollment in the MANTRA Phase III study by the end of 2023 with top line data in the first half of 2023. Cash runway extends into the first half of 2024, avoiding immediate need for additional equity financing. - Interim data readout for the MANTRA-2 study is expected in the fourth quarter of 2022 on approximately 10 evaluable patients. - Plan to start the MANTRA-3 and MANTRA-4 studies in the fourth quarter of 2022.

Forward-looking statements are subject to risks described in Rain’s annual report on Form 10-K for the year ended December 31, 2021, and subsequent SEC filings, including uncertainties in clinical trial outcomes, regulatory approvals, and potential differences between actual results and forward-looking expectations.

Q: Corinne Jenkins from Goldman Sachs asked about the cohort size for the MANTRA-2 tumor-agnostic basket study and what the FDA might require for accelerated approval.

A: Robert Doebele responded that prior examples for accelerated approval in diagnostic settings involve approximately 50 to 60 patients, depending on benefit magnitude and response rate, and Rain will follow data from other targeted therapies seeking agnostic approvals.

Q: Soumit Roy from Jones Trading asked about biomarkers in the MANTRA trial and Merkel cell carcinoma.

A: Richard Bryce said they are looking at MIC-1 as a surrogate biomarker in MANTRA, and Avanish Vellanki noted Merkel cell carcinoma has protein overexpression of MDM2 rather than gene amplification.

Q: Carly Kenselaar from Citi asked about MANTRA trial enrollment and frontline strategy.

A: Avanish Vellanki mentioned the BI study is for dose selection, and if MANTRA is successful, they would evaluate the first-line setting; Robert Doebele confirmed MANTRA-2 enrollment is on track with ~1.2% of patients meeting criteria.

Q: Yige Guo from Guggenheim Securities asked about MANTRA enrollment geography and tumor reduction kinetics.

A: Richard Bryce said MANTRA enrollment is global, and Robert Doebele stated response kinetics in MANTRA-2 are not yet determined from available data.