Purpose: Argininosuccinate synthetase 1 (ASS1) silencing in carcinomas and sarcomas leads to a dependence on extracellular arginine for survival. Arginine deprivation therapies, such as PEGylated arginine deiminase (ADI-PEG20), have shown limited effectiveness, which may be due to underlying mechanisms that inhibit apoptosis.
Experimental design: The effects of ADI-PEG20 on cell-cycle regulation, apoptosis, and BCL-XL-mediated survival pathways in ASS1-deficient cancer cells were determined. The mechanism of cell death protection was determined by assessing caspase and PARP cleavage, CDK2 activity, MCL1 expression, and the interactions among BCL-XL, BAX, and BAK. In vitro synergy was determined, and in vivo efficacy was modeled.
Results: Treatment with ADI-PEG20 led to reduced CDK2 activity and inhibited cell-cycle progression but did not induce significant cell death. BCL-XL was found to bind to BAX and BAK, preventing the initiation of apoptosis despite arginine starvation. Inhibition of BCL-XL allowed proapoptotic BAX and BAK to initiate the intrinsic apoptosis pathway, leading to increased cell death. This was found to be synergistic in vitro and efficacious in combination in vivo.
Conclusions: The study identifies BCL-XL as a key factor limiting the efficacy of arginine starvation therapies. Combining BCL-XL inhibitors with arginine deprivation strategies may overcome this resistance and enhance therapeutic outcomes. These findings provide a strong preclinical rationale for testing this combination approach in phase 1 clinical trials for ASS1-deficient cancers.
On December 16, 2022, the FDA approved the adenoviral vector-based gene therapy nadofaragene firadenovec-vncg (brand name Adstiladrin) for the treatment of adult patients with high-risk Bacillus Calmette-Guérin (BCG)-unresponsive non-muscle invasive bladder cancer (NMIBC) with carcinoma in situ (CIS). The product represents the first approved adenoviral vector-based gene therapy and the first approved gene therapy for bladder cancer. Determination of efficacy was based on results from Study rAd-IFN-CS-003 (Study CS-003), a single-arm trial in 98 evaluable patients with BCG-unresponsive NMIBC with CIS who received intravesical instillations of the gene therapy product (75 mL of nadofaragene firadenovec at 3 × 1011 viral particles per mL) once every 3 months. The major efficacy outcome measures were complete response (CR) at any time and duration of response. Fifty subjects experienced CR 3 months after the initial treatment (CR = 51%; 95% confidence interval, 40.7; 61.3%), of whom 46% remained in response for ≥12 months. The median duration of response was 9.7 months (range: 3-52+). Common adverse reactions included instillation site discharge, fatigue, bladder spasm, micturition urgency, hematuria, chills, pyrexia, and dysuria. The approval of nadofaragene firadenovec provides a new therapy option for patients with BCG-unresponsive NMIBC with CIS who are ineligible for cystectomy.
Purpose: Identifying biomarkers of radiotherapy (RT) response is important for optimizing the treatment of early breast cancer. In this study, we tested the interaction between endothelial cell (EC) expression of phospho-Tyr397-FAK (pY397-FAK) and adjuvant-RT on clinical outcomes after breast-conserving surgery (BCS) within a randomized study. Preclinical data suggest an enhanced effect of RT on low EC_pY397-FAK expression.
Experimental design: We analyzed tissue microarrays from the Swedish Breast Cancer Group 91 Radiotherapy (stage I-II, lymph node-negative) breast cancer cohort, consisting of 1,178 patients randomly assigned to receive either BCS alone or BCS plus adjuvant-RT. Tissue microarray sections were immunostained for pY397-FAK, CD31, α-smooth muscle actin, and pan-cytokeratin. HALO analysis scored mean pY397-FAK intensity in CD31+ ECs, pan-cytokeratin-positive tumor epithelial cells, and α-smooth muscle actin + mural/stromal cells per core. For 822 patients, multivariable Cox regression analysis was performed for the primary and secondary 5-year endpoints, locoregional recurrence and all recurrence, respectively, as dependent variables and RT and EC_pY397-FAK as independent variables.
Results: EC_pY397-FAK expression was not predictive for the primary endpoint locoregional recurrence (P = 0.098), but the direction of the RT effect was in line with preclinical findings. For the secondary endpoint all recurrence, there was a significant interaction (P = 0.026) between EC_pY397-FAK and RT. Without RT, higher EC_pY397-FAK expression resulted in a lower risk for all recurrence (HR = 0.74 per SD; 95% confidence interval = 0.57-0.96; P = 0.026).
Conclusions: Within the first 5 years following BCS, patients with low EC_pY397-FAK expression derive greater benefit from RT than patients with high EC_pY397-FAK expression. However, without RT, low EC_pY397-FAK expression is associated with a higher risk of recurrence.
Purpose: We evaluated the noncyclic dinucleotide stimulator of IFN genes agonist MK-2118 ± pembrolizumab in participants with advanced solid tumors or lymphomas.
Patients and methods: This first-in-human study (NCT03249792) enrolled participants with refractory, advanced solid tumors or lymphomas. Participants received intratumoral (IT) MK-2118 100 to 20,000 μg (arm 1), IT MK-2118 900 to 15,000 μg plus intravenous (IV) pembrolizumab 200 mg every 3 weeks (arm 2), or subcutaneous (SC) MK-2118 5,000 to 150,000 μg plus IV pembrolizumab 200 mg every 3 weeks (arm 4); arm 3 (visceral injection of MK-2118) was not pursued. IT dosing used an accelerated titration design and modified toxicity probability interval method; SC dosing (arm 4) was started subsequent to arms 1 and 2. The primary objectives were safety/tolerability. MK-2118 pharmacokinetics was a secondary endpoint; objective responses and biomarkers were exploratory endpoints.
Results: A total of 140 participants were enrolled (arm 1, n = 27; arm 2, n = 57; arm 4, n = 56). Grade 3/4 treatment-related adverse events occurred in 22%, 23%, and 11% of participants, respectively, but no maximum tolerated dose was identified up to MK-2118 20,000, 15,000, and 150,000 μg across the three arms. Dose-dependent increases in MK-2118 systemic exposure were observed following IT and subcutaneous administration. Objective responses were seen in 0%, 6%, and 4% of participants, respectively. IT MK-2118 led to dose-dependent changes in stimulator of interferon genes-based blood RNA expression levels, IFNγ, IFNγ-induced protein 10, and IL6; SC MK-2118 did not generate dose-related immune responses.
Conclusions: IT MK-2118 ± pembrolizumab and SC MK-2118 plus pembrolizumab had manageable toxicity and limited antitumor activity. IT but not SC administration demonstrated systemic immune effects.
Hypoxia is a common feature of solid tumors and is associated with a poor response to anticancer therapies. Hypoxia also induces metabolic changes, such as a switch to glycolysis. This glycolytic switch causes acidification of the tumor microenvironment (TME), thereby attenuating the anticancer immune response. A promising therapeutic strategy to reduce hypoxia and thereby sensitize tumors to irradiation and/or antitumor immune responses is pharmacological inhibition of oxidative phosphorylation (OXPHOS). Several OXPHOS inhibitors (OXPHOSi) have been tested in clinical trials. However, moderate responses and/or substantial toxicity have hampered clinical implementation. OXPHOSi tested in clinical trials inhibit the oxidative metabolism in tumor cells as well as healthy cells. Therefore, new strategies are needed to improve the efficacy of OXPHOSi while minimizing side effects. To enhance the therapeutic window, available OXPHOSi have, for instance, been conjugated to triphenylphosphonium to preferentially target the mitochondria of cancer cells, resulting in increased tumor uptake compared with healthy cells, as cancer cells have a higher mitochondrial membrane potential. However, OXPHOS inhibition also induces reactive oxygen species and subsequent antioxidant responses, which may influence the efficacy of therapies, such as platinum-based chemotherapy and radiotherapy. Here, we review the limitations of the clinically tested OXPHOSi metformin, atovaquone, tamoxifen, BAY 87-2243, and IACS-010759 and the potential of mitochondria-targeted OXPHOSi and their influence on reactive oxygen species production. Furthermore, the effect of the mitochondria-targeting moiety triphenylphosphonium on mitochondria is discussed as it affects mitochondrial bioenergetics.
Purpose: We aimed to investigate the efficacy and safety of anlotinib as adjuvant targeted therapy for completely resected localized high-grade soft-tissue sarcomas (STS).
Patients and methods: Patients with localized high-grade STS after complete resection were randomly assigned in a 1:1 ratio to receive either oral 12 mg anlotinib or placebo once daily on days 1 to 14 every 21 days as a cycle, with up to six cycles until disease relapse, unmanageable toxicity, or death. The efficacy and safety were analyzed. This trial was the first trial exploring adjuvant targeted therapy for STS (NCT03951571).
Results: Between June 2019 and November 2023, 88 patients were randomly assigned to receive anlotinib (n = 44) or placebo (n = 44). With a median follow-up of 30.95 months, the 1- and 2-year disease-free survival rates were 88% and 77% in the anlotinib group compared with 64% and 58% in the placebo group, respectively. Compared with patients treated with surgery alone, patients receiving adjuvant anlotinib combined with surgery had a reduced risk of disease recurrence [HR, 0.47; 95% confidence interval (CI), 0.22-1.00; P = 0.0445]. Based on the tumor histology, the reduced risk of disease recurrence with anlotinib versus placebo was observed in patients with myxofibrosarcoma (HR, 0.54; 95% CI, 0.17-1.65; P = 0.2698) and undifferentiated pleomorphic sarcoma (HR, 0.58; 95% CI, 0.12-2.87; P = 0.4971). Four patients discontinued anlotinib: two for proteinuria/hematuria (2/44, 5%) and two for poor healing of surgical wound (2/44, 5%).
Conclusions: Compared with surgery alone, adjuvant anlotinib following surgery reduces the incidence of disease relapse in localized high-grade STS, with acceptable toxicity.