The FDA has granted Fast Track designation to SNB-101, a novel polymer nanoparticle anticancer drug developed by SN Bioscience, for the treatment of small cell lung cancer (SCLC). This designation aims to expedite the development and review of drugs that address serious conditions and unmet medical needs.
Innovative Nanoparticle Formulation
SNB-101 is the first anticancer drug developed using SN-38, the active metabolite of irinotecan, formulated as nanoparticles. This innovative approach utilizes SN Bioscience's proprietary dual nano-micelle technology to improve drug delivery and reduce systemic toxicity. Preclinical and early-phase clinical results indicate that SNB-101 has improved tolerability and reduced gastrointestinal adverse effects compared to conventional anticancer agents in SCLC treatment. The drug has also demonstrated efficacy in lung cancer patients through targeted delivery to the lungs.
Phase 1 Clinical Trial Results
Preliminary results from a phase 1 study (NCT04640480) of SNB-101 in advanced solid tumors were presented at the 2023 ESMO Congress. As of the data cutoff on April 28, 2023, the study included 21 patients who received SNB-101. The objective response rate (ORR) was 14.29%, with all responses being partial responses. The disease control rate (DCR) was 42.86%, the median progression-free survival (PFS) was 1.97 months, and the median overall survival (OS) was 6.83 months.
The phase 1 trial enrolled patients aged 18 years or older with histologically or cytologically confirmed, locally advanced or metastatic solid tumors that had progressed following standard systemic therapy and were not candidates for complete surgical resection. Patients had to have measurable disease according to RECIST 1.1 criteria and an ECOG performance status of 0 or 1. Intravenous SNB-101 was administered at doses ranging from 5/8 mg/m2 to 50/80 mg/m2 on days 1 and 15 of each 28-day cycle until disease progression, unacceptable toxicity, or death.
The primary endpoints of the study included safety, dose-limiting toxicities (DLTs), and determination of the maximum tolerated dose (MTD) and recommended phase 2 dose (RP2D). Secondary endpoints included ORR, PFS, OS, DCR, and pharmacokinetics.
The patient population included those with colorectal cancer (n = 7), gastric cancer (n = 5), SCLC (n = 3), non–small cell lung cancer (NSCLC; n = 2), head and neck cancer (n = 2), esophageal cancer (n = 1), and soft-tissue sarcoma (n = 1). The mean age of the overall population was 58 years (range, 42-71), and patients had previously received 2 to 10 prior lines of treatment. Nine patients had prior exposure to irinotecan.
Safety and Tolerability
SNB-101 demonstrated a manageable toxicity profile at doses between 5 mg/m2 and 50 mg/m2. The MTD was not reached during dose escalation. One patient treated with 40/64 mg/m2 of SNB-101 experienced a DLT of febrile neutropenia. The most common treatment-related adverse events (AEs) of any grade were neutropenia (61.9%), decreased white blood cell counts (28.6%), nausea (23.8%), anemia (23.8%), and decreased platelet counts (19.0%).
Regulatory Designations and Future Plans
In addition to the Fast Track designation for SCLC, SNB-101 previously received orphan drug designation from the FDA for NSCLC in July 2023 and for pancreatic cancer in February 2024. SN Bioscience plans to initiate global clinical trials upon phase 2 approval in the United States and Europe in the second half of 2024. The company also intends to expand SNB-101's indications to other solid tumor types, such as colon cancer, gastric cancer, and biliary tract cancer, through additional phase 2 clinical trials.
SCLC remains a challenging disease with significant unmet medical needs. The current first-line treatment typically involves a combination of cisplatin and etoposide, classic cytotoxic anticancer drugs. SNB-101 represents a potential advancement in SCLC therapy, offering improved tolerability and targeted efficacy.
