To move forward with immunotherapy, it is important to understand how the tumor microenvironment generates systemic immunosuppression in patients with renal cell carcinoma (RCC) as well as in patients with other types of solid tumors. Even though antigen discovery in RCC has lagged behind melanoma, recent clinical trials have finally authenticated that RCC is susceptible to vaccine-based therapy. Furthermore, judicious coadministration of cytokines and chemotherapy can potentiate therapeutic responses to vaccine in RCC and prolong survival, as has already proved possible for melanoma. Although high-dose interleukin 2 immunotherapy has been superseded as first-line therapy for RCC by promiscuous receptor tyrosine kinase inhibitors (rTKIs) such as sunitinib, sunitinib itself is a potent immunoadjunct in animal tumor models. A reasonable therapeutic goal is to unite antiangiogenic strategies with immunotherapy as first-line therapy for RCC. This strategy is equally appropriate for testing in all solid tumors in which the microenvironment generates immunosuppression. A common element of RCC and pancreatic, colon, breast, and other solid tumors is large numbers of circulating myeloid-derived suppressor cells (MDSCs), and because MDSCs elicit regulatory T cells rather than vice versa, gaining control over MDSCs is an important initial step in any immunotherapy. Although rTKIs like sunitinib have a remarkable capacity to deplete MDSCs and restore normal T-cell function in peripheral body compartments such as the bloodstream and the spleen, such rTKIs are effective only against MDSCs, which are engaged in phospho-STAT3–dependent programming (pSTAT3+). Unfortunately, rTKI-resistant pSTAT3− MDSCs are especially apt to arise within the tumor microenvironment itself, necessitating strategies that do not rely exclusively on STAT3 disruption. The most utilitarian strategy to gain control of both pSTAT3+ and pSTAT3− MDSCs may be to exploit the natural differentiation pathway, which permits MDSCs to mature into tumoricidal macrophages (TM1) via such stimuli as Toll-like receptor agonists, interferon γ, and CD40 ligation. Overall, this review highlights the mechanisms of immune suppression used by the different regulatory cell types operative in RCC as well as other tumors. It also describes the different therapeutic strategies to overcome the suppressive nature of the tumor microenvironment.
109 Background: Since CPB may alter immune marker expression in key immunomodulatory populations such as myeloid-derived suppressor cells (MDSC) and CD8 + cytotoxic T lymphocytes (CTL), we evaluated PD1/PDL1 expression in longitudinal samples from mUC pts treated with CPB. Methods: Serial peripheral blood samples were collected from mUC pts who received CPB. PD1/PDL1 and VISTA expression was measured in MDSC (CD33 + HLADR − ) and CTL (CD8 + CD4 − ) from live peripheral blood mononuclear cells using flow cytometry. MDSC subsets were further defined as (G)ranulocytic (CD15 + CD14 − ), (M)onocytic (CD15 − CD14 + ), and (I)mmature (CD15 − CD14 − ). PD1/PDL1 and VISTA expression was presented as % of each MDSC subset or CTL. Wilcoxon signed-rank tests and mixed-model regression analyses were performed to assess changes in immune marker expression after CPB. Results: Of 30 CPB-treated pts with ≥ 2 blood samples for analysis, 21 received anti-PDL1 (20 atezolizumab/1 avelumab; [A]) and 9 received anti-PD1 (pembrolizumab [P]). Median age at diagnosis was 69.5 (4681), 77% men, 33% never smokers, 63% pure UC, 70% bladder primary, 20% prior intravesical BCG, 37% prior neoadjuvant chemotherapy, 63% prior cystectomy. Best overall responses to CPB were 3 PR/13 SD/5 PD (A) and 1 CR/1 PR/4 SD/3 PD (P). Successive doses of A correlated with decreased %PDL1 + M-MDSC, while those of P correlated with decreased %PD1 + M- and I- MDSC (Table). No significant changes in VISTA expression were detected. In 11 A-treated pts with samples before/after the 1st dose, %PDL1 + M- and I- MDSC decreased (median change −25.5 and −5.7; p = 0.02 and 0.03) and %PD1 + CTL increased (median change +2.4; p = 0.02) between 1st and 2nd samples. Conclusions: In this mUC pt cohort, distinct post-tx changes in %PD1/PDL1 in MDSC subsets and CTL occurred based on CPB (anti-PD1 vs anti-PDL1). Further analysis of correlations between CPB, immune marker expression, clinicopathologic factors, and outcomes is ongoing in a larger cohort. Mean absolute change in marker expression per dose in pts treated with CPB. [Table: see text]
Abstract The ability to induce T-cell apoptosis is one mechanism by which tumors evade the immune system, although the molecules involved remain controversial. We found that renal cell carcinoma (RCC)–induced T-cell apoptosis was inhibited by >50% when cocultures were performed with ganglioside-depleted tumor cells, caspase-8–negative lymphocytes, or anti–tumor necrosis factor-α (TNFα) antibodies, suggesting that tumor gangliosides synergize with signals delivered through TNFα death receptors to mediate T-cell killing. The synergy between tumor-derived TNFα and the RCC-overexpressed ganglioside GM1 for killing resting T cells is corroborated by studies using purified GM1 and rTNFα, which indicate that a 48-hour pretreatment with the ganglioside optimally sensitizes the lymphocytes to a TNFα-induced apoptotic death. However, activated T cells, which synthesize TNFα themselves, can be killed by exogenous GM1 alone. RelA-overexpressing lymphocytes are protected from GM1 plus TNFα-mediated apoptosis, a finding consistent with our previous studies indicating that gangliosides inhibit nuclear factor-κB activation. These results are clinically relevant because, similar to T-cells cocultured with GM1-overexpressing RCC lines, T cells isolated from the peripheral blood of patients with metastatic RCC are also heavily coated with that tumor-shed ganglioside. This population of patient cells, unlike T cells isolated from normal donors, is highly susceptible to apoptosis induced by rTNFα or by metastatic patient sera, which contain elevated levels of the cytokine. This report thus extends our previous studies by demonstrating that tumor-derived TNFα enhances RCC apoptogenicity not only by inducing ganglioside synthesis but also by initiating receptor-dependent apoptosis in T cells in which the nuclear factor-κB activation pathway has been inhibited by GM1. [Cancer Res 2008;68(6):2014–23]
PURPOSE Based on preclinical evidence that the antitumor effects of the combination of interleukin-2 (IL-2) and interferon alfa (IFN alpha) are greater than those of either cytokine alone, we have performed a phase I trial of recombinant IL-2 (rIL-2) and recombinant human IFN alpha 2a (rHuIFN alpha 2a) in patients with refractory malignancies. This study was an extension of an earlier trial that identified reversible myelosuppression as the dose-limiting toxicity of this combination. The present trial used modified definitions of unacceptable toxicity to allow exploration of higher doses of rIL-2. PATIENTS AND METHODS Both rHuIFN alpha 2a 10.0 x 10(6) U/m2 intramuscularly (IM) and rIL-2 were administered three times weekly for 4 consecutive weeks. IL-2 was given by intravenous (IV) bolus injection at doses that were escalated in successive cohorts of four to six patients, provided that toxicity at the preceding dose level was acceptable. Unacceptable toxicity was defined as an elevation of the serum creatinine level to greater than 5 mg/dL, an elevation of the serum bilirubin level to greater than 5 mg/dL, dyspnea at rest, hypotension refractory to pressors, altered mental status, or other toxicities of grade 3 to 4, using the National Cancer Institute (NCI) Common Toxicity Criteria. The doses of rIL-2 administered were 4.0 x 10(6), 6.0 x 10(6), 8.0 x 10(6), 10.0 x 10(6), 12.0 x 10(6), 14.0 x 10(6), 18.0 x 10(6), 22.0 x 10(6), and 26.0 x 10(6) BRMP (Hoffman-LaRoche) U/m2. At a dose of rIL-2 10.0 x 10(6) BRMP U/m2, patients were also treated with doses of rHuIFN alpha 2a of 1.0 x 10(6) and 0.1 x 10(6) U/m2. RESULTS A total of 57 patients were treated. Intolerable side effects (hypotension, pulmonary, and CNS toxicity) were produced by rIL-2 26.0 x 10(6) BRMP U/m2 and rHuIFN alpha 2a 10.0 x 10(6) U/m2. Two of 21 patients with renal cell carcinoma showed objective responses, and five of 17 patients with malignant melanoma responded. Two of these responses in melanoma were complete and continue to be longlasting. CONCLUSIONS When given with rHuIFN alpha 2a 10.0 x 10(6) U/m2 as described above, the maximum-tolerated dose of rIL-2 is 22.0 x 10(6) BRMP U/m2. This dose of rIL-2 is equivalent to 50 to 60 MIU/m2, depending on the conversion factor used. Based on this experience and other trials, we favor phase II trials in renal cell carcinoma using an alternative dose schedule of this cytokine combination, in which rIL-2 is administered by continuous infusion. We suggest that phase II trials of this combination in patients with melanoma use an rIL-2 dose of 8.0 x 10(6) BRMP U/m2 by IV bolus injection three times weekly in combination with rHuIFN alpha 2a 10.0 x 10(6) U/m2 IM three times weekly.
Eph receptors and their ligands, ephrins, are known to play important roles in organ development (formation of tissue boundaries, neural crest cell migration, axon guidance) and angiogenesis. In particular, EphA2 has recently attracted interest in the field of cancer research. Many observations, including our own, have demonstrated that most cancers, such as renal cell carcinoma (RCC), overexpress the EphA2 protein. EphA2 overexpression/dysregulation is associated with carcinogenesis, metastasis, and poor clinical prognosis. Indeed EphA2 is not just a marker of metastatic potential, but its overexpression is directly linked to an aggressive tumor phenotype. As a consequence, EphA2 represents a potential target for therapeutic intervention in the setting of EphA2+ cancer histologies, with several agents being developed with clinical intent. Several strategies can be contemplated in this regard, including: (1) selected promotion of EphA2 degradation or to reduce EphA2 expression and signaling (via the application of agonistic antibody, ephrin-A1 Fc fusion protein, siRNA against EphA2, or protein tyrosine phosphatases (PTP) that regulate EphA2 expression or specific EphA2 kinase inhibitors); (2) antagonism of EphA2 receptor-ligand binding (by provision of mimetic peptides or EphA2 Fc fusion protein); and/or (3) vaccination against EphA2 (using specific peptide-, protein-, or gene-based methods) to elicit specific T-cell- or Ig-mediated immunity. In this chapter, we will discuss the basic immunobiology of tumor-associated EphA2 and potential therapeutic interventions directed against EphA2 that may yield clinical benefit in the setting of (renal cell) cancer.
This study examines the antigen that stimulate production or release of a soluble helper factor(s) involved in development of cytotoxic T lymphocytes (CTL). Antigens associated with the Mls locus, I and K/D regions of the MHC were all capable of stimulating responder cells in MLC to produce helper factor. These supernatant fluids were all capable of providing "help" for the generation of cytotoxic T lymphocytes in MLC in which spleen cells are stimulated by allogeneic heat-treated thymocytes or splenocytes. Previous reports from our laboratory as well as others have shown that heat-treated cells do not stimulate a cytotoxic response. Heat-treatment of Mls, I, and H-2K/H-2D region incompatible stimulatory cells in MLC eliminated their ability to induce responder cells to produce helper factor, suggesting this is the mechanism whereby heat-treatment reduces the ability of cells to stimulate cell-mediated lympholysis (CML). The inability of supernatant fluids, from MLCs in which heat-treated cells were the stimulators, to assist in the generation of cytotoxic T cells did not appear to be the result of any suppressive factor induced by such treatment. Further, the antigens that stimulate pre-killer cells appear functionally distinct from those heat labile antigens (Mls, I, H-2K/H-2D associated) that stimulate helper factor production since heat-treated allogeneic cells served as stimulators of cytotoxicity provided helper activity was added to the MLC.
