Satsuma Pharmaceuticals, Inc. announced positive safety, tolerability and efficacy results from its recent analysis of the Company's ongoing STS101 ASCEND Phase 3 open-label, long-term safety trial. The primary objective of the ASCEND trial is to assess the safety and tolerability of STS101 in the acute treatment of migraine attacks over 6 and 12 months. Satsuma expects the results from this analysis, in addition to Phase 1 trial data and results from its ongoing SUMMIT Phase 3 efficacy trial, which the Company expects to announce in the fourth quarter of 2022, to support submission of a new drug application (NDA) with the U.S. Food and Drug Administration (FDA) planned for the first quarter of 2023.

Satsuma intends to seek marketing approval for and, if approved, commercialize STS101Mk2, which incorporates the improved, second-generation nasal delivery device. A secondary objective of the ASCEND open-label trial is to assess the efficacy of STS101 in the acute treatment of migraine attacks over time. In addition, exploratory post-hoc analyses were performed to assess the clinical performance of STS101Mk2 versus STS101Mk1.

STS101 demonstrated a favorable safety and tolerability profile, consistent with Phase 1 and Phase 3 clinical experience to date: Among 344 subjects who self-administered at least one dose of STS101Mk2, and in total more than 6,900 doses, to treat their migraine attacks on an as-needed basis for up to approximately 18 months (as of June 30, 2022), safety and tolerability results were as follows: No clinically relevant nasal safety or tolerability findings, clinically relevant systemic safety findings, or unexpected treatment-related serious adverse events were reported Treatment-related, treatment-emergent adverse events (TEAEs) reported among 5% or more of subjects or in 5% or more of attacks treated with STS101Mk2 were as follows: nasal discomfort, which occurred in 11% of subjects and 6.1% of treated attacks; and dysgeusia, which occurred in 7.6% of subjects and in 2.8% of treated attacks TEAEs were typically mild (82.7%) and transient Nausea or vomiting attributed to treatment with STS101Mk2 occurred infrequently: 1.7% of subjects reported nausea in 0.2% of total treated attacks, and 1.2% of subjects reported vomiting in 0.1% of total treated attacks A low proportion of subjects (4.1%) cited an adverse event as the reason for discontinuing participation in the trial Subject exposures over time STS101Mk2 exceed FDA requirement to support NDA filing and potential marketing approval: The number of subjects (n=166) who treated an average of at least two migraine attacks per month for at least six months with STS101Mk2 exceeded the 150-subject exposure-over-time requirement communicated to the Company by the FDA as necessary to support the planned NDA filing and potential marketing approval. STS101Mk2 efficacy observations: Among 172 trial participants who treated 1,932 migraine attacks exclusively with STS101Mk2: Freedom from pain by 2 hours post-treatment (2hPF response) was achieved in 34.2% of all treated attacks Freedom from most-bothersome-symptom by 2 hours post-treatment (2hMBS response) was achieved in 53.4% of all treated attacks In more than 81% of treated attacks, subjects did not report utilizing an allowed second dose of STS101Mk2 within 48 hours of administering the first dose In more than 94% of treated attacks, subjects did not report utilizing any rescue medications within 48 hours of administering STS101Mk2 A high proportion of treated attacks were characterized by baseline symptoms predictive of inadequate response to treatment, such as severe pain (47% of attacks), photophobia (97% of attacks), phonophobia (94% of attacks) and nausea (65% of attacks) Exploratory post-hoc analyses of STS101Mk2 versus STS101MK1 clinical performance: Among subjects who treated their first migraine attack following trial enrollment with STS101Mk2, the 2hPF and 2hMBS response rates for the first treated attack were respectively 7.8% and 6.9% greater, in absolute percentage points, than the corresponding 2hPF and 2hMBS response rates reported by subjects who treated their first migraine attack in the trial with STS101Mk1. The Company believes the higher first-treated-attack 2hPF and 2hMBS response rates achieved in the ASCEND trial with STS101Mk2 may reflect its demonstrated improved drug delivery performance versus STS101Mk1.

STS101Mk2 is being evaluated for efficacy and safety in the ongoing SUMMIT Phase 3, placebo-controlled trial. STS101 ASCEND Phase 3 Long-term Safety Trial: The STS101 ASCEND Phase 3 long-term safety trial is a multi-center, open-label trial in subjects with migraine that is being conducted in the United States. The primary objective of the ASCEND trial is to assess the safety and tolerability of STS101 in the acute treatment of migraine attacks over 6 and 12 months.

A secondary objective the trial is to assess the efficacy of STS101 in the acute treatment of migraine attacks over time. The trial is designed to meet the subject exposure-over-time requirements communicated by the FDA to Satsuma, and in accordance with recommendations contained in the FDA's current guidance document for industry. Initiated in August 2020, the ASCEND trial enrolled more than 480 subjects, 466 of whom self-administered at least one dose of either STS101Mk1 or STS101Mk2 study medication.

The Company completed a transition of study medication from STS101Mk1 to STS101Mk2 in the first half of 2021. As of June 30, 2022, study participants had treated more than 8,000 migraine attacks with more than 10,000 doses of STS101, and approximately 100 subjects remained active in the trial. Approximately 19% of subjects who enrolled in the trial were discontinued by the Company due to having an insufficient number of migraine attacks to contribute toward attainment of the exposure-over-time objectives for the trial.

STS101 is administered intermittently in the ASCEND trial to reflect the episodic nature of migraine and mimic the way in which patients often experience and treat migraine attacks. After establishing full eligibility, ASCEND trial participants are instructed to treat their migraine attacks with a single dose of STS101, and may do so for as long as approximately 18 months. Trial participants have the option of taking a second dose of STS101 or rescue medication to treat a nonresponding migraine or migraine recurrence, subject to a maximum of twelve doses of STS101 per month.

Programming of the electronic diary device utilized by ASCEND subjects may result in early efficacy data entry by trial participants. As in the previously-reported EMERGE Phase 3 efficacy trial, ASCEND subjects self-reported efficacy results using an electronic diary device that was programmed with an alarm to prompt study subjects to enter their efficacy results into the device prior to the nominal post-treatment timepoints.