Panbela Therapeutics, Inc. announced the presentation of interim clinical data from its Phase 1b combination therapy study of SBP-101, a proprietary polyamine analogue, with gemcitabine and nab-paclitaxel in patients with metastatic pancreatic ductal adenocarcinoma (PDA), at the American Society of Clinical Oncology (ASCO) Gastrointestinal (GI) Meeting that took place January 20-22, 2022. At the Phase 1b dose and schedule (N=30), CA19-9 levels decreased 60-99% in 70% of evaluable patients, with 1/29 (3%) achieving a complete remission, 13/29 evaluable patients achieving partial responses (45%) and 10/29 achieving stable disease at 8 weeks (34%). PFS was 6.0 months.

While PFS may be confounded by SBP-101 dosing holds implemented to investigate potential toxicity, the rates for 6-month PFS was 52% and for 12 month PFS was 10%. Nine subjects are in survival follow up as of the date the poster was presented at the ASCO GI meeting. Median OS is 12.0 months and is not final.

The safety population includes all subjects who received at least one dose of SBP-101 (N=50). The most common Grade =3 adverse events (AEs) related to any study medication were neutropenia in 20 subjects (19 attributed to G+A and 1 attributed to all 3) and elevated liver function tests in 14 subjects (5 attributed to SBP-101 and 9 attributed to all 3). SBP-101-related increases in LFTs were asymptomatic in all but 2 subjects and reversed in all subjects when SBP-101 administration was interrupted and dose-reduced or discontinued.

Additionally, seven subjects experienced serious vision adverse events (4 possibly related to SBP-101, 1 related to gemcitabine and 2 related to all 3 based on PI assessment). All were considered by the sponsor to be possibly related to SBP-101; 5 had findings consistent with retinopathy. The company has just begun a randomized trial to study SBP-101, as an addition to first-line treatment for metastatic PDA, will begin a neoadjuvant pancreatic trial this quarter and will begin an Ovarian Cancer program mid-year.

SBP-101 is a proprietary polyamine analogue designed to induce polyamine metabolic inhibition (PMI) by exploiting an observed high affinity of the compound for pancreatic ductal adenocarcinoma and other tumors. The molecule has shown potential signals of tumor growth inhibition in clinical studies of US and Australian metastatic pancreatic cancer patients, suggesting potential complementary activity with an existing FDA-approved standard chemotherapy regimen, if SPB-101 receives approval in the US. In data evaluated from clinical studies to date, SBP-101 has not shown exacerbation of bone marrow suppression and peripheral neuropathy, which can be chemotherapy-related adverse events.

Serious visual adverse events observed in the Company's recently completed Phase 1a/1b clinical trial have been evaluated and patients with a history of retinopathy or at risk of retinal detachment will be excluded from future SBP-101 studies. The safety data and PMI profile observed in the current Panbela sponsored clinical trial provides support for continued evaluation of SBP-101 in a randomized clinical trial.