Advances in rational combination chemotherapy

Efficacy and Safety of Corticosteroid in Combination with 5-Fluorouracil in the Treatment of Keloids and Hypertrophic Scars: A Systematic Review and Meta-analysis

BACKGROUND

Addressing hypertrophic scars and keloids poses a significant challenge in the realm of preventive and curative medicine. Combination corticosteroid with 5-fluorouracil (5-FU) is presumed to enhance the treatment of hypertrophic scars and keloids, although supportive evidence is lacking. This study is aimed at comparing the efficacy and safety profile of a combined corticosteroid and 5-FU regimen in treating hypertrophic scars and keloids.

METHODS

A comprehensive search was conducted for pertinent studies across various databases, including Web of Science, PubMed, Google Scholar, Cochrane Library, and Medline. The calculation of weighted mean difference (WMD), risk ratios (RR), odds ratios (OR), and 95% confidence intervals (CIs) was executed. Additionally, the Cochrane Collaboration's Risk of Bias Tool was utilized to evaluate potential bias risks.

RESULTS

A total of 15 studies were involved. The effectiveness based on patient self-assessment and the effectiveness based on observer assessment were significantly higher in the corticosteroid+5-FU group compared to those treated with control. A meta-analysis of scar height showed that the corticosteroid+5-FU group performed better than the control group (WMD = -0.38, 95% CI -0.58 to -0.18). There was no significant difference between the corticosteroid+5-FU group and the control group in improving scar vascularity, pliability and pigmentation. The result revealed that the corticosteroid+5-FU group of patients had less adverse effect of hypopigmentation, skin atrophy and telangiectasia than the control group.

CONCLUSION

The combined use of corticosteroids and 5-FU appears to be a more effective strategy for the treatment and prevention of hypertrophic scars and keloids, as evidenced by greater improvements in scar height and overall effectiveness, coupled with a reduced incidence of side effects.

LEVEL OF EVIDENCE II

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Additivity predicts the efficacy of most approved combination therapies for advanced cancer

Most advanced cancers are treated with drug combinations. Rational design aims to identify synergistic combinations, but existing synergy metrics apply to preclinical, not clinical data. Here we propose a model of drug additivity for progression-free survival (PFS) to assess whether clinical efficacies of approved drug combinations are additive or synergistic. This model includes patient-to-patient variability in best single-drug response plus the weaker drug per patient. Among US Food and Drug Administration approvals of drug combinations for advanced cancers (1995-2020), 95% exhibited additive or less than additive effects on PFS times. Among positive or negative phase 3 trials published between 2014-2018, every combination that improved PFS was expected to succeed by additivity (100% sensitivity) and most failures were expected to fail (78% specificity). This study shows synergy is neither a necessary nor common property of clinically effective drug combinations. The predictable efficacy of approved combinations suggests that additivity can be a design principle for combination therapies.

Synergistic antitumor activity of regorafenib and rosuvastatin in colorectal cancer

Introduction: Colorectal cancer is one of the most prevalent life-threatening malignant tumors with high incidence and mortality. However, the efficacy of current therapeutic regimens is very limited. Regorafenib has been approved for second- or third-line treatment of patients who are refractory to standard chemotherapy diagnosed with metastatic colorectal cancer, but its clinical efficacy needs to be further improved. Accumulating evidence demonstrates that statins also possess potent anticancer activities. However, whether regorafenib and statins pose synergistic anticancer effects in colorectal cancer is still unclear. Methods: Sulforhodamine B (SRB) assays were applied to evaluate the anti-proliferative activity of regorafenib or/and rosuvastatin in vitro, and immunoblotting analysis were applied to detect the effects of regorafenib/rosuvastatin combined treatment on mitogen-activated protein kinase (MAPK) signaling and apoptosis-related proteins. MC38 tumors were applied to investigate the synergistic anticancer effects of regorafenib in combination with rosuvastatin in vivo. Results: We found that regorafenib in combination with rosuvastatin exerted significant synergistic inhibition against colorectal cancer growth in vitro and in vivo. Mechanistically, regorafenib and rosuvastatin combination synergistically suppressed MAPK signaling, a crucial signaling pathway promoting cell survival, as indicated by the reduction of phosphorylated MEK/ERK. In addition, regorafenib in combination with rosuvastatin synergistically induced the apoptosis of colorectal cancer in vitro and in vivo. Discussion: Our study demonstrated the synergistic anti-proliferative and pro-apoptotic effects of regorafenib/rosuvastatin combined treatment in colorectal cancer in vitro/vivo and might potentially be evaluated as a novel combination regimen for clinical treatment of colorectal cancer.

Functional metabolomics reveal the role of AHR/GPR35 mediated kynurenic acid gradient sensing in chemotherapy-induced intestinal damage

Intestinal toxicity induced by chemotherapeutics has become an important reason for the interruption of therapy and withdrawal of approved agents. In this study, we demonstrated that chemotherapeutics-induced intestinal damage were commonly characterized by the sharp upregulation of tryptophan (Trp)−kynurenine (KYN)−kynurenic acid (KA) axis metabolism. Mechanistically, chemotherapy-induced intestinal damage triggered the formation of an interleukin-6 (IL-6)−indoleamine 2,3-dioxygenase 1 (IDO1)−aryl hydrocarbon receptor (AHR) positive feedback loop, which accelerated kynurenine pathway metabolism in gut. Besides, AHR and G protein-coupled receptor 35 (GPR35) negative feedback regulates intestinal damage and inflammation to maintain intestinal integrity and homeostasis through gradually sensing kynurenic acid level in gut and macrophage, respectively. Moreover, based on virtual screening and biological verification, vardenafil and linagliptin as GPR35 and AHR agonists respectively were discovered from 2388 approved drugs. Importantly, the results that vardenafil and linagliptin significantly alleviated chemotherapy-induced intestinal toxicity in vivo suggests that chemotherapeutics combined with the two could be a promising therapeutic strategy for cancer patients in clinic. This work highlights GPR35 and AHR as the guardian of kynurenine pathway metabolism and core component of defense responses against intestinal damage.

Metabolic interaction between amino acid deprivation and cisplatin synergistically reduces phosphoribosyl-pyrophosphate and augments cisplatin cytotoxicity

Cisplatin is a mainstay of cancer chemotherapy. It forms DNA adducts, thereby activating poly(ADP-ribose) polymerases (PARPs) to initiate DNA repair. The PARP substrate NAD⁺ is synthesized from 5-phosphoribose-1-pyrophosphate (PRPP), and we found that treating cells for 6 h with cisplatin reduced intracellular PRPP availability. The decrease in PRPP was likely from (1) increased PRPP consumption, because cisplatin increased protein PARylation and PARP1 shRNA knock-down returned PRPP towards normal, and (2) decreased intracellular phosphate, which down-regulated PRPP synthetase activity. Depriving cells of a single essential amino acid decreased PRPP synthetase activity with a half-life of ~ 8 h, and combining cisplatin and amino acid deprivation synergistically reduced intracellular PRPP. PRPP is a rate-limiting substrate for purine nucleotide synthesis, and cisplatin inhibited de novo purine synthesis and DNA synthesis, with amino acid deprivation augmenting cisplatin’s effects. Amino acid deprivation enhanced cisplatin’s cytotoxicity, increasing cellular apoptosis and DNA strand breaks in vitro, and intermittent deprivation of lysine combined with a sub-therapeutic dose of cisplatin inhibited growth of ectopic hepatomas in mice. Augmentation of cisplatin’s biochemical and cytotoxic effects by amino acid deprivation suggest that intermittent deprivation of an essential amino acid could allow dose reduction of cisplatin; this could reduce the drug’s side effects, and allow its use in cisplatin-resistant tumors.

Experimental chemotherapy against canine mammary cancer xenograft in SCID mice and its prediction of clinical effect

The effectiveness of 6 antitumor agents has been evaluated for canine mammary gland tumor (CMG-6) serially transplanted into severe combined immunodeficiency (SCID) mice. CMG-6 diagnosed as a solid carcinoma was subcutaneously transplanted into SCID mice and six antitumor agents were intravenously given to the mice as a single injection. The effectiveness was evaluated by Treatment group/Control group percent (T/C %) and statistical significance determined by Mann-Whitney's U-test in tumor volume. The minimum effective doses (MEDs; mg/kg) of mice were as follows; cyclophosphamide (CPM) 65, doxorubicin (DXR) 6, cisplatin (CDDP) 5, vincristine (VCR) 1.6, vinblastine (VLB) more than 5.5, 5-fluorouracil (5-FU) 105. Clinical effects of the drugs were predicted based on area under the curve (AUC) of dogs given a clinical dose (AUCdog)/AUC of mice given a MED (AUCmouse) ratios from published references. The AUC ratios were as follows; CPM 2.24, DXR 0.19, CDDP 1.20, VCR 0.04, VLB <1.24 and 5-FU 1.15. Drugs indicating more than 1.0 in AUCdog/AUCmouse ratio were CPM, CDDP and 5-FU, and would be suggested as effective in the original patient with CMG-6. The combination chemotherapy using clinically equivalent doses in CDDP and CPM, which were the two highest values in AUCdog/AUCmouse ratio by single agent therapy, was performed and shown to have additional effects as compared to the responsiveness of each agent against CMG-6.

Client counseling for cancer: considerations for making a professional and skillful presentation of treatment options, risks, and therapeutic goals

Each veterinary oncology patient is different, yet the verbal presentation of therapeutic options to the owner contains many similar concepts. Helping a client choose a treatment option and adjust to that therapy is an exchange process between the veterinarian and the client in which each party is responsible for certain duties. To review the principles presented in this article, a list of responsibilities for each participant, essential to facilitate a decision about cancer therapy for the pet, is presented in Table 1.

Antibiotic C3368-A, a fungus-derived nucleoside transport inhibitor, potentiates the activity of antitumor drugs

Antibiotic C3368-A (CA) is produced by a fungus strain from a soil sample collected in Antarctica. CA markedly inhibited radiolabeled thymidine and uridine transport in mouse Ehrlich carcinoma cells, its 50% inhibitory concentration (IC50) being 4.6 and 7.7 microM, respectively. In clonogenic assay, CA displayed a synergistic effect with methotrexate (MTX), mitomycin C (MMC), 5-fluorouracil (5FU), and Adriamycin (ADR) against human oral epidermoid carcinoma KB cells. CA also markedly enhanced the inhibitory effect of 5FU and ADR on the proliferation of human hepatoma BEL-7402 cells as determined by the p-nitrophenyl-N-acetyl-beta-D-glucosaminide (NAG) enzyme-reaction assay. 5FU or ADR cytotoxicity was not augmented by CA in human fetal lung 2BS cells. In vivo, CA significantly potentiated the inhibitory effect of MMC against colon carcinoma 26 in mice. No significant augmentation of toxicity by the combination was found in treated mice. The results suggest that CA, the newly found nucleoside-transport inhibitor, may be useful in potentiation of the effect of antitumor drugs.

Antileukemic activity studies and cellular pharmacology of the analogues of 2-hydroxy-1H-isoindole-1,3-dione (HISD) alone and in combination with cytosine arabinoside (ara-C) against human leukemia cells CEM/0

The 2-hydroxy-1H-isoindole-1,3-dione (HISD) derivatives are inhibitors of ribonucleotide reductase (RR). Among the seven new compounds of the PL series, three were found to be active in cell lines sensitive (CEM/0) or resistant to ara-C (CEM/ara-C/7A; CEM/dCk[-]. The compounds PL4, PL7 and PL8 exhibited IC50 values in micromolar range against the three CEM cell lines. The 3 compounds showed 100- to 1000-fold higher cytotoxicity compared to HU against all three CEM cell lines. Combination of each of the three active PL compounds with ara-C showed high degree of synergism in comparison to the combinations of HU with ara-C against both CEM/0 and CEM/ara-C/7A cell lines. The DNA synthetic capacity of CEM/0 cells treated with 10 microM PL4 for 24 or 48 h was inhibited > or = 99.8% simultaneously the cellular NTP pools were severely depleted. Treatment of CEM/0 cells with 10 microM PL4 showed steady depletion in all the dNTP pools at 1 or 2 h and complete depletion by 4 h. The enzyme activity did not recover up to 48 h in presence of the drug suggesting irreversible inhibition of RR.

Synthesis and testing of new antileukemic Schiff bases of N-hydroxy-N'-aminoguanidine against CCRF-CEM/0 human leukemia cells in vitro and synergism studies with cytarabine (Ara-C)

A series of eight new N-hydroxy-N'-aminoguanidine (HAG) Schiff bases [ArCH = NNHC(= NH)NHOH.tosylate] was synthesized as potential antitumor agents through the inhibition of the enzyme ribonucleotide reductase (EC 1.17.4.1). Five of the HAG derivatives (LK02 through LK06) were designed to contain an orthohydroxy group on the phenyl ring of ArCH = to increase the stability of the Schiff base formed. In addition, two compounds with a substituted quinoline [LK10; ArCH = (4-hydroxy-7-trifluoromethylquinolin-3-yl)methylene] or isoquinoline (LK11; ArCH = (5-nitroisoquinolin-1-yl)methylene] moiety were synthesized through multiple-step reactions involving reduction and/or oxidation. The IC50 values of the newly synthesized HAG Schiff bases were determined against human leukemic CCRF-CEM/0 cells in culture. The IC50 values of two previously reported HAG derivatives [ATL25; ArCH = (5-nitro-isoquinolin-1-yl)methylene] and [LW02; ArCH = 2-hydroxy-3-allyl-benzylidene)] were also determined for the first time against CCRF-CEM/0 cells. Among the compounds tested, LK11 was found to be the most potent (IC50, 2.95 +/- 0.1 microM) and the 4-methoxy-2-hydroxyphenyl derivative (LK02) to be the least potent (IC50, 121 +/- 16 microM). LK11 was about 15-fold more potent against CCRF-CEM/0 cells compared to the parent compound hydroxyguanidine sulfate (IC50, 46 +/- 7.1 microM) and was about 32 times more potent than LK10 (IC50, 97.6 +/- 0.9 microM). LK11 in combination was incubated in sequence with cytarabine (ara-C) at various molar ratios against CCRF-CEM/0 cells for 48 hr. The results were analyzed using both the isobologram and the median-effect methods.(ABSTRACT TRUNCATED AT 250 WORDS)

Combination chemotherapy tested in a short-term thymidine incorporation assay in primary cultures of ovarian adenocarcinomas

Fifty-six tumor specimens from patients with ovarian adenocarcinoma were tested for sensitivity to single and combination drug regimens in a short-term antimetabolic assay measuring inhibition of thymidine incorporation. Response in primary cultures to drug combinations was compared with response to each component drug: cisplatinum, chlorambucil, adriamycin, etoposide and activated cyclophosphamide. Using cut-off criteria previously shown to correlate with "sensitive" and "resistant" tumors for single drugs, 11% of tumors showed increased sensitivity to a combination compared with the single drugs, but 10% showed decreased sensitivity to a combination. The majority of tumors remained in the same "sensitive" or "resistant" categories obtained with the single drugs. Analysis by isobolograms demonstrated synergy, addition or antagonism with the same combination on different tumors. No significant difference between combinations and the best single drug used alone was found in 70% of assays. Overall thymidine incorporation inhibition by the combination and by the best single drug was highly correlated. It is suggested that the best single drug predicts the effectiveness of its combination regimens.

Potentiation of antimetabolite antitumor activity in vivo by dipyridamole and amphotericin B

Previous studies have shown that dipyridamole (DP), a potent nucleoside transport inhibitor blocking the rescue effect of exogenous nucleosides, markedly potentiates the cytotoxicity of antimetabolites. However, no enhancement of the chemotherapeutic effect of antimetabolites by DP in vivo has yet been reported. This study provided evidence that the combination of DP and amphotericin B (AmB) significantly potentiated the inhibitory effect of 5-fluorouracil (FU) or methotrexate (MTX) against a panel of transplantable tumors including sarcoma 180, cervical carcinoma U14, and Lewis lung carcinoma in mice. No significant increase in toxicity was induced by this combination in treated mice. Our results indicate that the combination of DP and AmB with antimetabolites is potentially useful in cancer chemotherapy.

A rapid in vitro screening system for the identification and evaluation of anticancer drugs

We report the development of an in vitro screening system that can be used to identify new anticancer drugs that are specifically cytotoxic for dividing cells. The screening system takes advantage of the potential of many cell lines, including tumor cells, to stop dividing when they are plated at high cell density. The cytotoxic effects of anticancer drugs on dividing (i.e., cells plated at low cell density) and nondividing cells (i.e., cells plated at high cell density) is measured by the incorporation of 51Cr. This in vitro system was evaluated by measuring the cytotoxic effects of the anticancer drugs cisplatin, thiotepa, doxorubicin, methotrexate, and vinblastine on the cell lines B/C-N, ME-180, and MCF-7. In this in vitro system the concentrations of the anticancer drugs that produced significant cytotoxicity on only dividing cells are similar to the concentrations that are used clinically. The fact that this in vitro system is rapid, simple, applicable to many cell types, and able to predict effective concentrations of anticancer drugs should make it useful for the screening of new anticancer drugs and for the design of preclinical studies.