RAPA-201 Therapy of Solid Tumors

The therapy of solid tumors has been revolutionized by immune therapy, in particular, approaches that activate immune T cells in a polyclonal manner through blockade of checkpoint pathways such as PD-1 by administration of monoclonal antibodies. In this study, the investigators will evaluate the adoptive transfer of RAPA-201 cells, which are checkpoint-deficient polyclonal T cells that represent an analogous yet distinct immune therapy treatment platform for solid tumors. The administration of polyclonal, metabolically-fit RAPA-201 cells is a novel adoptive T cell therapy approach that is suitable for regenerative medicine efforts.

RAPA-201 is a novel immunotherapy product consisting of reprogrammed autologous CD4+ and CD8+ T cells of Th1/Tc1 cytokine phenotype. RAPA-201, which have acquired resistance to the mTOR inhibitor temsirolimus, are manufactured ex vivo from peripheral blood mononuclear cells collected from solid tumor patients using a steady-state apheresis. The novel RAPA-201 manufacturing platform, which incorporates both an mTOR inhibitor (temsirolimus) and an anti-cancer Th1/Tc1 polarizing agent (IFN-alpha) generates polyclonal T cells with five key characteristics:

1. Th1/Tc1: polarization to anti-cancer Th1 and Tc1 subsets, with commensurate down-regulation of immune suppressive Th2 and regulatory T (TREG) subsets; 2. T Central Memory: expression of a T central memory (TCM) phenotype, which promotes T cell engraftment and persistence for prolonged anti-tumor effects; 3. Rapamycin-Resistance: acquisition of rapamycin-resistance, which translates into a multi-faceted anti-apoptotic phenotype that improves T cell fitness in the stringent conditions of the tumor microenvironment; 4. T Cell Quiescence: reduced T cell activation, as evidence by reduced expression of the IL-2 receptor CD25, which reduces T cell-mediated cytokine toxicities such as cytokine-release syndrome (CRS) that limit other forms of T cell therapy; and 5. Reduced Checkpoints: multiple checkpoint inhibitory receptors are markedly reduced on RAPA-201 cells (including but not limited to PD-1, CTLA4, TIM-3, LAG3, and LAIR1), which increases T cell immunity in the checkpoint-replete, immune suppressive tumor microenvironment.

This is a non-randomized, open label, multi-site, phase I/II trial of outpatient RAPA-201 immune T cell therapy in patients with advanced metastatic, recurrent, and unresectable solid tumors that have recurred or relapsed after prior immune therapy. Patients must have tumor relapse after at least one prior line of therapy and must have refractory status to the most recent regimen, which must include an anti-PD-(L)1 monoclonal antibody. Furthermore, accrual focuses upon solid tumor disease types potentially amenable to standard-of-care salvage chemotherapy consisting of the carboplatin + paclitaxel (CP) regimen that will be utilized for host conditioning prior to RAPA-201 therapy. Importantly, carboplatin and paclitaxel are "immunogenic" chemotherapy agents whereby the resultant cancer cell death mechanism is favorable for generation of anti-tumor immune T cell responses. Thus, the CP regimen that this protocol incorporates is intended to directly control tumor progression and indirectly promote anti-tumor T cell immunity.

Protocol therapy consists of six cycles of standard-of-care chemotherapy (carboplatin + paclitaxel (CP) regimen) administered in the outpatient setting every 28 days (chemotherapy administered on cycles day 1, 8, and 15). RAPA-201 cells will be administered at a target flat dose of 400 X 10\^6 cells per infusion on day 3 of cycles 2 through 6.

In the original protocol design, a sample size of up to 22 patients was selected to determine whether RAPA-201 therapy, when used in combination with the CP regimen, represents an active regimen in solid tumors that are resistant to anti-PD(L)-1 checkpoint inhibitor therapy, as defined by a response rate (≥ PR) consistent with a rate of 35%. The first stage of protocol accrual consisted of n=10 patients; to advance to the second protocol accrual stage (accrual of an additional n=12 patients), RAPA-201 therapy must result in a tumor response (≥ PR) in at least 2 out of the 10 initial patients. As described below in the detailed description, this original protocol implementation demonstrated that RAPA-201 represented an active treatment regimen for solid tumor patients, and as such, the protocol was expanded to evaluate the combination of RAPA-201 therapy followed by anti-PD1 maintenance therapy.