Abstract 757P
Background
For patients (pts) with advanced sarcomas in the relapsed/refractory setting, few effective treatment options exist. The likelihood of response or tumor control diminishes with each subsequent line of therapy. Monotherapy of PD-L1 inhibitors has shown modest to no activity in sarcomas, especially in tumors with low or no PD-L1 expression. Natural killer (NK) cells have been implicated in the antitumor response to immune checkpoint inhibitors (CIs) with evidence suggesting a role in PD-L1-negative tumors. SNK01 is a first-in-kind, autologous nongenetically modified NK cell therapy with highly enhanced cytotoxicity and over 90% activating receptor expression which can be consistently produced from heavily pre-treated pts.
Methods
Single pt INDs in eight pts with metastatic sarcoma using SNK01 (2 x 109) and 200 mg pembrolizumab (P-SNK) or 240 mg nivolumab (N-SNK) were authorized by the USFDA CBER and Western IRB for compassionate use. All pts were PD-L1 negative or had <10% PD-L1 expression. Many had progressed on prior CIs. Pts received P-SNK Q3W (n=6) or N-SNK Q2W (n=2) until progression or unacceptable toxicity.
Results
Pts had a median of 5 prior therapies (range 3-8). Subtypes included leiomyosarcoma, small round cell sarcoma, endometrial stomal sarcoma, Ewing’s sarcoma, radiation induced chondrosarcoma, and osteosarcoma. As of April 30, 2022, three pts are alive at 21, 28, and 29 months from initiation of treatment. There were no grade 2 or 3 adverse events. Best objective response by RECIST 1.1 was CR in 1 pt, who continues on P-SNK over 28 months, and PR in two pts (ORR 37.5%). Of pts who progressed, some reported improvement in their QoL and became eligible to be treated with salvage chemotherapy, resulting in additional clinical response.
Conclusions
SNK01 combined with CIs appears to be safe and demonstrates clinical activity against several types of heavily pre-treated advanced sarcoma, independent of PD-L1 status. It may also keep rapidly progressing disease stable enough to allow additional cytotoxic chemotherapy. This intriguing combo data warrants further study.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
NKGen Biotech.
Funding
NKGen Biotech.
Disclosure
S.P. Chawla: Financial Interests, Personal, Funding: NKGen Biotech. B. Gibson: Financial Interests, Personal, Full or part-time Employment: NKGen Biotech. P. Chang: Financial Interests, Personal, Full or part-time Employment: NKGen Biotech. P.Y. Song: Financial Interests, Personal, Stocks/Shares: NKGen Biotech. All other authors have declared no conflicts of interest.