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Supplementary Figures 1-8

Figure S1 shows combination treatment induces splenomegaly and T cells Apoptosis Figure S2 shows PD-L1 is increased on splenic T cells with combination treatment Figure S3 shows combination treatment increases costimulatory receptors on T cells Figure S4 shows delayed anti-PD-1 and anti-PD-L1 are ineffective at tumor control Figure S5 shows sequential combination provides anti-tumor immunity in the 4T1 model. Figure S6 shows sequential combination does not induce inflammatory cytokines Figure S7 shows sequential combination does not increase costimulatory receptors Figure S8 shows combination treatment induces functional PyMT-specific T cells

Purpose: Antibodies specific for inhibitory checkpoints PD-1 and CTLA-4 have shown impressive results against solid tumors. This has fueled interest in novel immunotherapy combinations to affect patients who remain refractory to checkpoint blockade monotherapy. However, how to optimally combine checkpoint blockade with agents targeting T-cell costimulatory receptors, such as OX40, remains a critical question.Experimental Design: We utilized an anti-PD-1–refractory, orthotopically transplanted MMTV-PyMT mammary cancer model to investigate the antitumor effect of an agonist anti-OX40 antibody combined with anti-PD-1. As PD-1 naturally aids in immune contraction after T-cell activation, we treated mice with concurrent combination treatment versus sequentially administering anti-OX40 followed by anti-PD-1.Results: The concurrent addition of anti-PD-1 significantly attenuated the therapeutic effect of anti-OX40 alone. Combination-treated mice had considerable increases in type I and type II serum cytokines and significantly augmented expression of inhibitory receptors or exhaustion markers CTLA-4 and TIM-3 on T cells. Combination treatment increased intratumoral CD4+ T-cell proliferation at day 13, but at day 19, both CD4+ and CD8+ T-cell proliferation was significantly reduced compared with untreated mice. In two tumor models, sequential combination of anti-OX40 followed by anti-PD-1 (but not the reverse order) resulted in significant increases in therapeutic efficacy. Against MMTV-PyMT tumors, sequential combination was dependent on both CD4+ and CD8+ T cells and completely regressed tumors in approximately 30% of treated animals.Conclusions: These results highlight the importance of timing for optimized therapeutic effect with combination immunotherapies and suggest the testing of sequencing in combination immunotherapy clinical trials. Clin Cancer Res; 23(20); 6165–77. ©2017 AACR.See related commentary by Colombo, p. 5999

Background SARS-CoV-2 (CoV2) has precipitated a global pandemic and the effectiveness of standard vaccine strategies to induce potent and persistent immunity to CoV2 is in question, particularly for the elderly. This problem is not dissimilar to what we have struggled with in our quest to induce immunity to cancer antigens, where vaccine-induced anti-cancer immune responses can be weak. Here, we describe a novel vaccine approach which leverages electroporation (EP) of a plasmid encoding a prefusion stabilized CoV2 spike protein (CORVax). As IL-12 has been shown to augment the efficacy of immunotherapy in aged mice,1 we have initiated studies to evaluate if plasmid IL-12 (TAVO™) can similarly augment anti-CoV2 immune responses in young mice and have planned studies in aged animals. Methods A prefusion stabilized CoV2 spike plasmid expression vector was constructed, a master cell bank generated and clinical-grade plasmid manufactured. C57BL/6 and BALB/c were vaccinated via intramuscular (IM) and/or intradermal (ID) injection followed immediately by EP of plasmids encoding the CoV2 spike protein with or without plasmid-encoded murine IL-12 on days 1 and 14 or 21. Mice were followed for >120 days to assess safety. Splenocytes and serum were harvested at different time points to interrogate virus-specific cellular responses as well anti-spike IgG1/IgG2 antibody titers. A surrogate viral neutralization test (sVNT) assessed serum blockade of soluble hACE2R binding to immobilized CoV2 spike. Results Preliminary data shows that EP of CORVax alone or combined with IL-12 was safe. EP of CORVax was able to elicit anti-Spike IgG antibodies (IC50 = 1/2112), as well as IgG antibodies targeting the receptor binding domain of the Spike protein (IC50 = 1/965) approximately 40 days after the booster vaccination. In 2 of 2 experiments, CORVax combined with IL-12 significantly (P Conclusions Early preclinical data shows that EP of CORVax can induce IgG responses to CoV2 Spike and the receptor binding domain (RBD) as well as apparent viral neutralizing activity. The addition of IL-12, at least transiently, increased sVNT titer. We plan to investigate alternate vaccine boosting strategies while extending these studies into aged animals and initiate a clinical trial in the near future. References Ruby CE, Weinberg AD. OX40-Enhanced tumor rejection and effector T cell differentiation decreases with age. J Immunol2009;182:1481–9. https://doi.org/10.4049/jimmunol.182.3.1481.

Human babesiosis is a tick-borne multisystem disease, and current treatments have both adverse side effects and a significant rate of drug failure. Lawres et al. report that endochin-like quinolones, in combination with atovaquone, cure experimental babesiosis in immunodeficient mice., Human babesiosis is a tick-borne multisystem disease caused by Babesia species of the apicomplexan phylum. Most clinical cases and fatalities of babesiosis are caused by Babesia microti. Current treatment for human babesiosis consists of two drug combinations, atovaquone + azithromycin or quinine + clindamycin. These treatments are associated with adverse side effects and a significant rate of drug failure. Here, we provide evidence for radical cure of experimental babesiosis in immunodeficient mice using a combination of an endochin-like quinolone (ELQ) prodrug and atovaquone. In vivo efficacy studies in mice using ELQ-271, ELQ-316, and the ELQ-316 prodrug, ELQ-334, demonstrated excellent growth inhibitory activity against the parasite, with potency equal to that of orally administered atovaquone at 10 mg/kg. Analysis of recrudescent parasites after ELQ or atovaquone monotherapy identified genetic substitutions in the Qi or Qo sites, respectively, of the cytochrome bc1 complex. Impressively, a combination of ELQ-334 and atovaquone, at doses as low as 5.0 mg/kg each, resulted in complete clearance of the parasite with no recrudescence up to 122 d after discontinuation of therapy. These results will set the stage for future clinical evaluation of ELQ and atovaquone combination therapy for treatment of human babesiosis.

Purpose: Antibodies specific for inhibitory checkpoints PD-1 and CTLA-4 have shown impressive results against solid tumors. This has fueled interest in novel immunotherapy combinations to affect patients who remain refractory to checkpoint blockade monotherapy. However, how to optimally combine checkpoint blockade with agents targeting T-cell costimulatory receptors, such as OX40, remains a critical question.Experimental Design: We utilized an anti-PD-1–refractory, orthotopically transplanted MMTV-PyMT mammary cancer model to investigate the antitumor effect of an agonist anti-OX40 antibody combined with anti-PD-1. As PD-1 naturally aids in immune contraction after T-cell activation, we treated mice with concurrent combination treatment versus sequentially administering anti-OX40 followed by anti-PD-1.Results: The concurrent addition of anti-PD-1 significantly attenuated the therapeutic effect of anti-OX40 alone. Combination-treated mice had considerable increases in type I and type II serum cytokines and significantly augmented expression of inhibitory receptors or exhaustion markers CTLA-4 and TIM-3 on T cells. Combination treatment increased intratumoral CD4+ T-cell proliferation at day 13, but at day 19, both CD4+ and CD8+ T-cell proliferation was significantly reduced compared with untreated mice. In two tumor models, sequential combination of anti-OX40 followed by anti-PD-1 (but not the reverse order) resulted in significant increases in therapeutic efficacy. Against MMTV-PyMT tumors, sequential combination was dependent on both CD4+ and CD8+ T cells and completely regressed tumors in approximately 30% of treated animals.Conclusions: These results highlight the importance of timing for optimized therapeutic effect with combination immunotherapies and suggest the testing of sequencing in combination immunotherapy clinical trials. Clin Cancer Res; 23(20); 6165–77. ©2017 AACR.See related commentary by Colombo, p. 5999

With the recent success of cancer immunotherapies targeting specific inhibitory receptors like PD-1 and CTLA-4, there is great interest in how to combine these drugs with other novel therapies targeting costimulatory receptors that could further augment an anti-tumor response. Recently, we observed that orthotopically-transplanted MMTV-PyMT tumor-bearing mice that received anti-OX40 treatment saw a significant delay in tumor growth (p < 0.001) compared to untreated mice. However when combined concurrently with anti-PD-1 blockade, instead of a synergistic effect, we noted no additive benefit, and in fact saw a significant attenuation (p < 0.05) in survival. These results fit a similar pattern to what we have seen in the 4T1 tumor model, where the anti-tumor effect provided by vaccine plus anti-OX40, was significantly attenuated (p < 0.001) when anti-PD-1 was added concurrently. We hypothesized that treating with anti-PD-1 antibody would be more effective during the contraction phase of the T cell boost generated by anti-OX40. Thus we delayed anti-PD-1 treatment until after anti-OX40 dosing was complete and saw a significant delay (p < 0.01) in tumor growth and subsequent increase (p < 0.01) in survival in the PyMT transplant model (compared to anti-OX40 alone), with some of the tumors reaching full regression. We had also previously seen a similar significant antitumor effect (p < 0.001) in the 4T1 tumor model. These results were reproduced using delayed treatment with an anti-PD-L1 antibody combined with anti-OX40, demonstrating that blocking either side of the PD-1-PD-L1 interaction is sufficient. Also supporting this hypothesis, we noted a significant increase (p < 0.05 compared to untreated) in PD-1 expression on CD4+ T cells during and after anti-OX40 treatment. Investigating the effects of the concurrent combination, we noticed a striking increase in IFN-γ in the serum compared to treatment with single agent (p < 0.001 after 3 doses). Serum levels of other cytokines TNF, IL-4, IL-6, and IL-10 were also elevated in the combination treated group compared to anti-OX40 alone. Interestingly, we observed a large increase in PD-L1 expression on both CD4+ and CD8+ T cells and we also noted significant increases (p < 0.05) in inhibitory receptors LAG3, TIM3 and CTLA4 on CD4+ and CD8+ splenic T cells. These may provide additional escape mechanisms for the tumor to evade immune destruction and potentially offer other targets to enhance combination therapy. Our results demonstrate that the sequence of antibody treatment targeting both costimulatory and inhibitory receptors is critical to success of the combined therapy. These data offer a strong rationale for delaying PD-1 blockade until after costimulation has provided an initial immune boost. Citation Format: David J. Messenheimer, Zipei Feng, Keith W. Wegmann, Shawn M. Jensen, Carlo B. Bifulco, Bernard A. Fox. Timing of PD-1 blockade is critical to successful synergy with OX40 costimulation in preclinical mammary tumor models. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4361.

Sontochin was the original chloroquine replacement drug, arising from research by Hans Andersag 2 years after chloroquine (known as “resochin” at the time) had been shelved due to the mistaken perception that it was too toxic for human use. We were surprised to find that sontochin, i.e., 3-methyl-chloroquine, retains significant activity against chloroquine-resistant strains of Plasmodium falciparum in vitro . We prepared derivatives of sontochin, “pharmachins,” with alkyl or aryl substituents at the 3 position and with alterations to the 4-position side chain to enhance activity against drug-resistant strains. Modified with an aryl substituent in the 3 position of the 7-chloro-quinoline ring, Pharmachin 203 (PH-203) exhibits low-nanomolar 50% inhibitory concentrations (IC 50 s) against drug-sensitive and multidrug-resistant strains and in vivo efficacy against patent infections of Plasmodium yoelii in mice that is superior to chloroquine. Our findings suggest that novel 3-position aryl pharmachin derivatives have the potential for use in treating drug resistant malaria.

Background Rapamycin, a potent immune modulator, is used to treat transplant rejection and some autoimmune diseases. Uveitis is a potentially severe inflammatory eye disease, and 2 clinical trials of treating uveitis with rapamycin are under way. Unexpectedly, recent research has demonstrated that low dose rapamycin enhances the memory T cell population and function. However, it is unclear how low dose rapamycin influences the immune response in the setting of uveitis. Design and Methods B10.RIII mice were immunized to induce experimental autoimmune uveitis (EAU). Ocular inflammation of control and rapamycin-treated mice was compared based on histological change. ELISPOT and T cell proliferation assays were performed to assess splenocyte response to ocular antigen. In addition, we examined the effect of rapamycin on activation-induced cell death (AICD) using the MitoCapture assay and Annexin V staining. Results Administration of low dose rapamycin exacerbated EAU, whereas treating mice with high dose rapamycin attenuated ocular inflammation. The progression of EAU by low dose rapamycin coincided with the increased frequency of antigen-reactive lymphocytes. Lastly, fewer rapamycin-treated T cells underwent AICD, which might contribute to exaggerated ocular inflammation and the uveitogenic immune response. Conclusion These data reveal a paradoxical role for rapamycin in uveitis in a dose-dependent manner. This study has a potentially important clinical implication as rapamycin might cause unwanted consequences dependent on dosing and pharmacokinetics. Thus, more research is needed to further define the mechanism by which low dose rapamycin augments the immune response.

Multiple Ag peptides (MAPs) containing eight proteolipid protein (PLP)139–151 peptides arranged around a dendrimeric branched lysine core were used to influence the expression and development of relapsing experimental allergic encephalomyelitis (EAE) in SJL mice. The PLP139–151 MAPs were very efficient agents in preventing the development of clinical disease when administered after immunization with the PLP139–151 monomeric encephalitogenic peptide in CFA. The treatment effect with these MAPs was peptide specific; irrelevant multimeric peptides such as guinea pig myelin basic protein GPBP72–84 MAP (a dendrimeric octamer composed of the 72–84 peptide) and PLP178–191 MAP (a dendrimeric octamer composed of the PLP178–191 peptide) had no treatment effect on PLP139–151-induced EAE. PLP139–151 MAP treatment initiated after clinical signs of paralysis also altered the subsequent course of EAE; it limited developing signs of paralysis and effectively limited the severity and number of disease relapses in MAP-treated mice over a 60-day observation period. PLP139–151 MAP therapy initiated before disease onset acts to limit the numbers of Th17 and IFN-γ-producing cells that enter into the CNS. However, Foxp3+ cells entered the CNS in numbers equivalent for nontreated and PLP139–151 MAP-treated animals. The net effect of PLP139–151 MAP treatment dramatically increases the ratio of Foxp3+ cells to Th17 and IFN-γ-producing cells in the CNS of PLP139–151 MAP-treated animals.

The adoptive transfer of clinical and histopathologic signs of experimental allergic encephalomyelitis (EAE) requires MHC compatibility between cell donor and cell recipient. The results of adoptive transfer studies using F1 to parent bone marrow chimeras as recipients of parental-derived BP-sensitive spleen cells indicate that this restriction is not expressed at the level of the endothelial cell but is confined to the cells of bone marrow derivation. Furthermore, these results indicate that the development of EAE is not dependent on the activity of MHC-restricted cytotoxic cells.

In the presence of IL-6, transforming growth factor (TGF)-beta1 induces differentiation of T helper (Th) 17 cells in mice. Interleukin (IL)-23, a heterodimeric cytokine composed of IL-23p19 and IL-12/23p40 subunits, stimulates the growth and expansion of Th17 cells, and has been implicated in psoriasis pathogenesis. To study the associations between TGF-beta1, the IL-23/Th17 inflammatory pathway, and psoriasis, we investigated inflammatory skin disease in transgenic mice that constitutively overexpress human TGF-beta1 in basal keratinocytes (K5.hTGF-beta1 transgenic mice); these mice had previously been reported as having a psoriasis-like disease. K5.hTGF-beta1 transgenic mice had high levels of TGF-beta1 mRNA and protein in both skin and serum. Levels of cytokines involved in IL-23/Th17-mediated inflammation were not elevated in lesional skin compared with those in non-lesional and wild-type skin. It is noteworthy that IL-4 and IgE were markedly elevated in inflamed skin and serum, respectively, of transgenic mice. Monoclonal antibodies (mAbs) specifically directed against IL-23p19 or IL-12/23p40 had no clinical effect on established inflammatory skin disease in K5.hTGF-beta1 transgenic mice, whereas the same mAbs were able to block the development of murine experimental autoimmune encephalomyelitis, an IL-23/Th17-mediated disease. In summary, the IL-23/Th17 inflammatory pathway is not responsible for the maintenance of inflammatory skin disease in K5.hTGF-beta1 transgenic mice.