Rubius Therapeutics, Inc. announced updated clinical data from the ongoing monotherapy Phase 1 arm of the Phase 1/2 clinical trial of RTX-240 in patients with advanced solid tumors at the American Association for Cancer Research Annual Meeting. Updated Data from the Phase 1 Trial of RTX-240 in Patients with Advanced Solid Tumors: Nine dose cohorts (n=34) were completed in the monotherapy solid tumor arm of the trial at the time of the data cutoff on March 4, 2022, with 34 patients evaluable for safety (primary outcome measure) and 27 patients evaluable for efficacy (secondary outcome measure). Enrollment continues in the 5e10 Q3W dose cohort.

As of the cutoff date, disease control was observed in 10 patients (1 partial response, 2 unconfirmed partial responses and 7 with stable disease), 9 of whom had experienced disease progression on prior anti-PD-1/anti-PD-L1 therapy. There were three best responses of partial response (PR) in non-small cell lung cancer (NSCLC), anal cancer and uveal melanoma patients: An unconfirmed PR (uPR) with 41% decrease of all target lesions and a notable decrease of an external protruding chest wall mass in a patient with non-small cell lung cancer (NSCLC) whose disease had progressed on prior anti-PD-L1 therapy; A confirmed PR with a 54% reduction in the target lesions in a patient with metastatic anal cancer whose disease had progressed on anti-PD-L1 therapy; and An uPR with 100% decrease of the target hepatic lesion and resolution of multiple non-target hepatic lesions in a patient with metastatic uveal melanoma whose disease had progressed on anti-PD-1 therapy. Stable disease was observed in 5 patients, including 3 with metastatic NSCLC and 2 with renal cell carcinoma (RCC) across the 3e10 cohorts, supporting the Company's decision to expand the Phase 1 arm of RTX-240 plus pembrolizumab to NSCLC and RCC patients.

One patient each with NSCLC and RCC remained on monotherapy treatment with SD greater than 6 months as of the cutoff date. As of the cutoff date, RTX-240 has been shown to have been generally well tolerated with no treatment-related or investigator-identified immune-related Grade 3/4 adverse events (AEs) and no dose-limiting toxicities. Based on the totality of clinical, tolerability and pharmacodynamic data, a recommended monotherapy Phase 2 dose of 5e10 cells administered every 3 weeks was selected.

This dose will be further explored in the combination expansion cohort of NSCLC and RCC patients. Rubius also announced final clinical results from the Phase 1 arm of monotherapy RTX-240 in relapsed/refractory AML. As of the cutoff date of March 4, 2022, seventeen patients were enrolled across 4 dose levels.

No DLTs were observed and there were 3 treatment-related Grade 3/4 adverse events. There were no investigator-reported immune-related AEs. Five patients had SD greater than 3 months, and 1 patient had a significant blast count reduction (53% to 6%).

Upcoming Anticipated Milestones: To evaluate the full potential of RTX-240, Rubius' other oncology programs and the RED PLATFORM, Rubius plans to execute several critical milestones within the next 12 months and has sufficient cash runway into the second half of 2023: Report initial Phase 1 clinical results for RTX-321 for the treatment of HPV 16-positive cancers during the second half of 2022; Report initial Phase 1 clinical results for RTX-240 in combination with pembrolizumab in advanced solid tumors and data from the additional NSCLC and RCC patients in the second half of 2022; Select a clinical candidate for the first autoimmune program in type 1 diabetes during the second half of 2022; and Report initial Phase 1 clinical results for RTX-224 for the treatment of advanced solid tumors during the first quarter of 2023.