The use of biologics (peptide and protein based drugs) has increased significantly over the past few decades. However, their development has been limited by their short half-life, immunogenicity and ...low membrane permeability, restricting most therapies to extracellular targets and administration by injection. Lipidation is a clinically-proven post-translational modification that has shown great promise to address these issues: improving half-life, reducing immunogenicity and enabling intracellular uptake and delivery across epithelia. Despite its great potential, lipidation remains an underutilized strategy in the clinical translation of lead biologics. We review how lipidation can overcome common challenges in biologics development as well as highlight gaps in our understanding of the effect of lipidation on therapeutic efficacy, where increased research and development efforts may lead to next-generation drugs.
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The genomes of cancers deficient in mismatch repair contain exceptionally high numbers of somatic mutations. In a proof-of-concept study, we previously showed that colorectal cancers with mismatch ...repair deficiency were sensitive to immune checkpoint blockade with antibodies to programmed death receptor–1 (PD-1). We have now expanded this study to evaluate the efficacy of PD-1 blockade in patients with advanced mismatch repair–deficient cancers across 12 different tumor types. Objective radiographic responses were observed in 53% of patients, and complete responses were achieved in 21% of patients. Responses were durable, with median progression-free survival and overall survival still not reached. Functional analysis in a responding patient demonstrated rapid in vivo expansion of neoantigen-specific T cell clones that were reactive to mutant neopeptides found in the tumor. These data support the hypothesis that the large proportion of mutant neoantigens in mismatch repair–deficient cancers make them sensitive to immune checkpoint blockade, regardless of the cancers’ tissue of origin.
Tumors with mismatch repair deficiency (MMR-d) are characterized by sequence alterations in microsatellites and can accumulate thousands of mutations. This high mutational burden renders tumors ...immunogenic and sensitive to programmed cell death-1 (PD-1) immune checkpoint inhibitors. Yet, despite their tumor immunogenicity, patients with MMR-deficient tumors experience highly variable responses, and roughly half are refractory to treatment. We present experimental and clinical evidence showing that the degree of microsatellite instability (MSI) and resultant mutational load, in part, underlies the variable response to PD-1 blockade immunotherapy in MMR-d human and mouse tumors. The extent of response is particularly associated with the accumulation of insertion-deletion (indel) mutational load. This study provides a rationale for the genome-wide characterization of MSI intensity and mutational load to better profile responses to anti-PD-1 immunotherapy across MMR-deficient human cancers.
Response to programmed cell death protein 1 (PD-1) blockade is often conceptualized as resulting from reinvigoration of tumor-infiltrating lymphocytes. However, recruited antitumor immunity from the ...periphery may also be an important contributor to response. A detailed assessment of the response dynamics of individual metastasis could provide insight to the systemic and local features that mediate response and resistance to immunotherapy.
Patients with metastatic non-small-cell lung cancer (NSCLC) or mismatch repair deficiency (MMRD) carcinoma treated with PD-1 monotherapy were evaluated independently. Absolute and percent change of each target lesion were quantified at each computed tomography scan using RECIST. Patterns of progression were predefined as systemic or mixed and were correlated with clinical outcomes.
A total of 761 individual lesions from 214 patients with NSCLC and 290 lesions from 78 patients with MMRD carcinoma were examined. Individual target lesion responses aligned with best overall response of each patient (85% NSCLC and 93% MMRD lesions responded in patients with partial response/complete response). In responding patients, timing of response was uniform (73% NSCLC and 76% MMRD lesions responded synchronously), and deeper responses were associated with prolonged progression-free survival and overall survival. By contrast, at progression, mixed progression was common (45% of NSCLC and 53% of MMRD) and associated with improved survival compared with those who experienced systemic progression (NSCLC hazard ratio HR, 0.58;
= .001; MMRD HR, 0.40;
= .07). Organ sites had differential responses, with lymph node and liver metastasis among the most and least responsive, respectively.
Temporal-spatial patterns of response across individual metastases tend to be uniform, favoring the role of peripheral, clonally directed antitumor immunity as a key mediator of response to PD-1 blockade. In contrast, progression is more heterogeneous, potentially revealing the clinical importance of local features and intertumoral heterogeneity.
Microsatellite instability (MSI) and high tumor mutation burden (TMB-High) are promising pan-tumor biomarkers used to select patients for treatment with immune checkpoint blockade; however, real-time ...sequencing of unresectable or metastatic solid tumors is often challenging. We report a noninvasive approach for detection of MSI and TMB-High in the circulation of patients.
We developed an approach that utilized a hybrid-capture-based 98-kb pan-cancer gene panel, including targeted microsatellite regions. A multifactorial error correction method and a novel peak-finding algorithm were established to identify rare MSI frameshift alleles in cell-free DNA (cfDNA).
Through analysis of cfDNA derived from a combination of healthy donors and patients with metastatic cancer, the error correction and peak-finding approaches produced a specificity of >99% (
= 163) and sensitivities of 78% (
= 23) and 67% (
= 15), respectively, for MSI and TMB-High. For patients treated with PD-1 blockade, we demonstrated that MSI and TMB-High in pretreatment plasma predicted progression-free survival (hazard ratios: 0.21 and 0.23,
= 0.001 and 0.003, respectively). In addition, we analyzed cfDNA from longitudinally collected plasma samples obtained during therapy to identify patients who achieved durable response to PD-1 blockade.
These analyses demonstrate the feasibility of noninvasive pan-cancer screening and monitoring of patients who exhibit MSI or TMB-High and have a high likelihood of responding to immune checkpoint blockade.
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Approximately 10% of patients with mismatch repair-proficient (MMRp) colorectal cancer showed clinical benefit to anti-PD-1 monotherapy (NCT01876511). We sought to identify biomarkers that delineate ...patients with immunoreactive colorectal cancer and to explore new combinatorial immunotherapy strategies that can impact MMRp colorectal cancer.
We compared the expression of 44 selected immune-related genes in the primary colon tumor of 19 patients with metastatic colorectal cancer (mCRC) who responded (
= 13) versus those who did not (
= 6) to anti-PD-1 therapy (NCT01876511). We define a 10 gene-based immune signature that could distinguish responder from nonresponder. Resected colon specimens (
= 14) were used to validate the association of the predicted status (responder and nonresponder) with the immune-related gene expression, the phenotype, and the function of tumor-infiltrating lymphocytes freshly isolated from the same tumors.
Although both IL17
and IL17
immunoreactive MMRp colorectal cancers are associated with intratumor correlates of adaptive immunosuppression (CD8/IFNγ and PD-L1/IDO1 colocalization), only IL17
MMRp tumors (3/14) have a tumor immune microenvironment (T
ME) that resembles the T
ME in primary colon tumors of patients with mCRC responsive to anti-PD-1 treatment.
The detection of a preexisting antitumor immune response in MMRp colorectal cancer (immunoreactive MMRp colorectal cancer) is not sufficient to predict a clinical benefit to T-cell checkpoint inhibitors. Intratumoral IL17-mediated signaling may preclude responses to immunotherapy. Drugs targeting the IL17 signaling pathway are available in clinic, and their combination with T-cell checkpoint inhibitors could improve colorectal cancer immunotherapy.
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Immune checkpoint blockade (ICB) has been a remarkable clinical advance for cancer; however, the majority of patients do not respond to ICB therapy. We show that metastatic disease in the pleural and ...peritoneal cavities is associated with poor clinical outcomes after ICB therapy. Cavity-resident macrophages express high levels of Tim-4, a receptor for phosphatidylserine (PS), and this is associated with reduced numbers of CD8+ T cells with tumor-reactive features in pleural effusions and peritoneal ascites from patients with cancer. We mechanistically demonstrate that viable and cytotoxic anti-tumor CD8+ T cells upregulate PS and this renders them susceptible to sequestration away from tumor targets and proliferation suppression by Tim-4+ macrophages. Tim-4 blockade abrogates this sequestration and proliferation suppression and enhances anti-tumor efficacy in models of anti-PD-1 therapy and adoptive T cell therapy in mice. Thus, Tim-4+ cavity-resident macrophages limit the efficacy of immunotherapies in these microenvironments.
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•Metastatic involvement of the serous body cavities portends worse ICB outcomes•Tim-4 levels on human macrophages correlate with reduced CD8+ CD39+ T cells•Tim-4+ macrophages sequester and impair proliferation of CD8+ T cells•Tim-4 blockade enhances the efficacy of ICB and adoptive T cell therapy in mice
Chow et al. demonstrate that metastatic involvement of the pleural and peritoneal cavities is associated with poor ICB efficacy in patients with cancer. Tim-4+ cavity-resident macrophages directly impair CD8 T cell function, and Tim-4 blockade enhances the efficacy of ICB and adoptive T cell therapy in mice.
We report improved NADPH flux and xylitol biosynthesis in engineered E. coli. Xylitol is produced from xylose via an NADPH dependent reductase. We utilize 2-stage dynamic metabolic control to compare ...two approaches to optimize xylitol biosynthesis, a stoichiometric approach, wherein competitive fluxes are decreased, and a regulatory approach wherein the levels of key regulatory metabolites are reduced. The stoichiometric and regulatory approaches lead to a 20-fold and 90-fold improvement in xylitol production, respectively. Strains with reduced levels of enoyl-ACP reductase and glucose-6-phosphate dehydrogenase, led to altered metabolite pools resulting in the activation of the membrane bound transhydrogenase and an NADPH generation pathway, consisting of pyruvate ferredoxin oxidoreductase coupled with NADPH dependent ferredoxin reductase, leading to increased NADPH fluxes, despite a reduction in NADPH pools. These strains produced titers of 200 g/L of xylitol from xylose at 86% of theoretical yield in instrumented bioreactors. We expect dynamic control over the regulation of the membrane bound transhydrogenase as well as NADPH production through pyruvate ferredoxin oxidoreductase to broadly enable improved NADPH dependent bioconversions or production via NADPH dependent metabolic pathways.
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•Decreases in NADPH pools lead to increased NADPH fluxes.•Pyruvate ferredoxin oxidoreductase coupled with NADPH-ferredoxin reductase improves NADPH production in vivo.•Dynamic reduction in acyl-ACP/CoA pools alleviate inhibition of membrane bound transhydrogenase and improve NADPH flux.•Xylitol titers >200 g/L in fed batch fermentations with xylose as a sole feedstock.
Two studies in previously treated metastatic pancreatic cancer have been completed combining GVAX pancreas vaccine (GM-CSF-secreting allogeneic pancreatic tumor cells) with cyclophosphamide (Cy) and ...CRS-207 (live, attenuated
-expressing mesothelin). In the current study, we compared Cy/GVAX followed by CRS-207 with (Arm A) or without nivolumab (Arm B).
Patients with pancreatic adenocarcinoma who received one prior therapy for metastatic disease and RECIST measurable disease were randomized 1:1 to receive treatment on Arm A or Arm B. The primary objective was to compare overall survival (OS) between the arms. Additional objectives included assessment of progression-free survival, safety, tumor responses, CA19-9 responses, and immunologic correlates.
Ninety-three patients were treated (Arm A, 51; Arm B, 42). The median OS in Arms A and B were 5.9 95% confidence interval (CI), 4.7-8.6 and 6.1 (95% CI, 3.5-7.0) months, respectively, with an HR of 0.86 (95% CI, 0.55-1.34). Objective responses were seen in 3 patients using immune-related response criteria (4%, 2/51, Arm A; 2%, 1/42, Arm B). The grade ≥3 related adverse event rate, whereas higher in Arm A (35.3% vs. 11.9%) was manageable. Changes in the microenvironment, including increase in CD8
T cells and a decrease in CD68
myeloid cells, were observed in long-term survivors in Arm A only.
Although the study did not meet its primary endpoint of improvement in OS of Arm A over Arm B, the OS was comparable with standard therapy. Objective responses and immunologic changes in the tumor microenvironment were evident.
Background
Epigenetic abnormalities are manifold in all solid tumors and include changes in chromatin configuration and DNA methylation. The authors designed a phase 1 study to evaluate the oral DNA ...methyltransferase inhibitor CC‐486 combined with the histone deacetylase inhibitor romidepsin in advanced solid tumors with dose expansion to further evaluate pharmacodynamics and possible clinical benefit of the recommended phase 2 dose (RP2D).
Methods
This was a phase 1 study with a 3 + 3 dose‐escalation design and an expansion phase for patients with virally mediated cancers. The disease control rate (DCR) was the primary outcome for the expansion cohort. Correlative studies included long interspersed nucleotide element 1 (LINE‐1) methylation and drug exposure in blood samples (clinicaltrials.gov identifier NCT01537744).
Results
Fourteen patients were enrolled in the dose‐escalation portion at 3 dose levels. Three patients experienced dose‐limiting toxicities; the RP2D was oral CC‐486 300 mg daily on days 1 through 14 and romidepsin 8 mg/m2 on days 8 and 15. Because of slow accrual into the expansion phase, the trial was closed after 4 patients enrolled. Common toxicities of the combination included nausea (83.3%), anorexia (72.2%), fatigue (61.1%), and constipation (55.6%). There were 12 patients evaluable for response, 5 with stable disease, of whom 2 received >4 cycles; there were no responses. Exposure to CC‐486 and romidepsin was consistent with prior data. LINE‐1 methylation on C1D8 was significantly reduced (mean, −6.23; 95% CI, −12.23, −0.24; P = .04).
Conclusions
Although, at the RP2D, the combination of CC‐486 and romidepsin was tolerable, no significant anticancer activity was observed. Significant demethylation in post‐treatment circulating tumor DNA and biopsies provided proof of target acquisition.
The combination of CC‐486 and romidepsin is safe and tolerable; however, although pharmacodynamic data confirm on‐target effects, no significant anticancer activity is observed. Further development in combination with other antineoplastic therapies may be feasible.
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