FDA Grants Fast Track Designation to SYS6090 in Pretreated MSS/pMMR mCRC

The FDA has granted fast track designation to SYS6090 (JMT108) for the treatment of patients with microsatellite-stable (MSS) or mismatch repair–proficient (pMMR) metastatic colorectal cancer (mCRC) that has progressed on standard systemic therapies, according to a news release from CSPC Pharmaceutical Group Limited.¹

The designation addresses a population with limited treatment options. The median overall survival (OS) for patients with MSS/pMMR mCRC who have received third-line and subsequent therapies generally remains under 12 months, according to the company. CSPC did not report specific efficacy figures for SYS6090 in support of the grant; phase 1 studies of the agent are underway in both China and the United States, including a phase 1b/2 trial (NCT07750041) evaluating SYS6090 in combination with bevacizumab (Avastin) with or without chemotherapy.^1,2

Fast track designation is intended to facilitate development and expedite the review of therapies that treat serious conditions and address an unmet medical need, and it enables more frequent interaction with the FDA, rolling review of a future application, and eligibility for priority review if relevant criteria are met.¹ CSPC said the designation will facilitate and expedite the development and approval of SYS6090 in the United States, as well as globally.

Other agents are being developed for the same difficult-to-treat setting; the CDH17-directed antibody-drug conjugate SOT109 received fast track designation for previously treated advanced unresectable or mCRC earlier in 2026.³

What is the mechanism of action of SYS6090?

SYS6090 is a first-in-class PD-1/IL-15 bispecific fusion protein that simultaneously blocks PD-1 and activates the IL-15 signaling pathway, according to CSPC. The company reported that the agent's asymmetric structure precisely directs IL-15 activity in a PD-1–dependent fashion, an approach intended to concentrate immune activation within the tumor microenvironment.¹

MSS/pMMR colorectal tumors are generally considered poorly responsive to PD-1 monotherapy, in contrast to the mismatch repair–deficient (dMMR)/microsatellite instability–high (MSI-H) subset. By pairing PD-1 blockade with IL-15–driven activation and expansion of effector T cells and natural killer cells, the agent is designed to generate antitumor immunity in a setting where checkpoint inhibition alone has shown limited activity.

How is the phase 1b/2 SYS6090 combination study designed?

The phase 1b/2 study is evaluating SYS6090 in combination with other therapies in patients with unresectable advanced or metastatic pMMR/MSS colorectal cancer.² The randomized, open-label, parallel-assignment trial plans to enroll approximately 260 patients who must be at least 18 years of age with histologically confirmed pMMR/MSS mCRC featuring at least one measurable lesion per RECIST 1.1 criteria. Patients also needed to have an ECOG performance status of 0 or 1. Those with active central nervous system metastases or interstitial lung disease are excluded.

The phase 1b portion is evaluating SYS6090 at 2 fixed doses in combination with bevacizumab in second- or third-line disease to establish the recommended phase 2 dose (RP2D). The phase 2 portion comprises a second- and third-line cohort that is randomly assigning patients to SYS6090 at the RP2D plus bevacizumab and mFOLFOX6, SYS6090 plus bevacizumab, or regorafenib (Stivarga) as a control, along with a first-line cohort comparing SYS6090 plus bevacizumab and FOLFOXIRI with bevacizumab plus FOLFOXIRI.

Primary end points include the RP2D, safety and tolerability, objective response rate (ORR) per RECIST 1.1, and progression-free survival (PFS).²

What are the next steps for SYS6090 in CRC?

The agent remains in early clinical development, with phase 1 evaluation ongoing in China and the United States.¹ CSPC noted that the fast track designation provides a framework to advance SYS6090 toward later-stage study in MSS/pMMR mCRC, a subtype that constitutes the majority of colorectal cancers and for which effective later-line options are limited.

References

1. SYS6090 (JMT108) granted fast track designation by U.S. FDA for treatment of patients with MSS/pMMR mCRC. News release. CSPC Pharmaceutical Group Limited. August 26, 2026. Accessed August 27, 2026. https://doc.irasia.com/listco/hk/cspc/announcement/a260826a.pdf
2. A phase Ib/II study to evaluate the safety, tolerability, and efficacy of SYS6090 in combination with other therapies in participants with advanced colorectal cancer. ClinicalTrials.gov. Updated August 2026. Accessed August 27, 2026. https://clinicaltrials.gov/study/NCT07750041
3. FDA grants fast track designation to SOT109 in advanced colorectal cancer. OncLive. Published July 14, 2026. Accessed August 27, 2026. https://www.onclive.com/view/fda-grants-fast-track-designation-to-sot109-in-advanced-colorectal-cancer