Distinct cDC subsets co-operate in CD40 agonist response while suppressive microenvironments and lack of antigens subvert efficacy

Agonistic αCD40 therapy has shown to inhibit cancer progression, but only in a fraction of patients. Hence, understanding the cancer cell-intrinsic and microenvironmental determinants of αCD40 therapy response is crucial to identify responsive patient populations and design efficient combination treatments. Here, we showed that the therapeutic efficacy of αCD40 in responder melanoma tumours, relied on pre-existing cDC1-primed CD8+ T cells, however cDC1s were dispensable after αCD40 administration. Surprisingly, in response to αCD40 the abundance of activated cDCs, potentially derived from cDC2s increased, thereby further activating antitumour CD8+ T cells. Hence, distinct cDC subsets are required to induce αCD40 responses. By contrast, lung tumours, characterised by a high abundance of macrophages, were resistant to αCD40 therapy. Combining αCD40 therapy with macrophage depletion led to tumour growth inhibition only in the presence of strong neoantigens. Accordingly, treatment with immunogenic cell-death inducing chemotherapy sensitised non-immunogenic tumours to αCD40 therapy.

CCS1477, a Novel p300/CBP Bromodomain Inhibitor, Enhances Efficacy of Azacitidine and Venetoclax in Pre-Clinical Models of Acute Myeloid Leukaemia and Lymphoma

E1A binding protein (p300) and CREB binding protein (CBP) are two closely related histone acetyl transferases that co-activate key oncogenes such as MYC and IRF4 which are relevant in a number of haematological malignancies. Here we describe the effects of CCS1477, a new orally available inhibitor of the p300/CBP bromodomains, given alone or in combination with azactidine or venetoclax in pre-clinical models of AML and B-cell lymphoma. As a monotherapy, daily oral dosing with CCS1477 (5, 10 and 20mg/kg) caused a significant dose-dependent reduction in tumour growth in a MOLM-16 xenograft model of AML, with regressions observed at the highest and well tolerated dose of 20mg/kg/qd. The inhibition of tumour growth during drug treatment was accompanied by a significant reduction in tumour expression of MYC by qPCR. In murine retroviral transduction and transplantation models of human AML initiated by either MLL-AF10 or MLL-AF9, daily monotherapy by oral gavage with CCS1477 at 30mg/kg for 42 days, caused a highly significant prolongation of survival. All seven control treated mice died of AML within 160 days whereas only one of seven CCS1477 treated mice had died in each model by 300 days. In the MOLM-16 xenograft model, a sub-maximal dose of CCS1477 (10mg/kg) demonstrated superior tumour growth inhibition by comparison with azacitidine (0.5mg/kg i.p) and with significant combination benefit when these two agents were combined. In this same model venetoclax (50 or 100 mg/kg/qd oral) had no effect on tumour growth, indicating that MOLM-16 tumours are intrinsically resistant. CCS1477 dosed daily at 10mg/kg restored sensitivity to venetoclax as evidenced by significantly greater tumour growth inhibition when compared with CCS1477 given alone. In a venetoclax-sensitive xenograft model of AML (MV-4-11), CCS1477 (10mg/kg) and venetoclax (100mg/kg) resulted in a similar and partial reduction in tumour growth over a 21 day dosing period. When venetoclax and CCS1477 were combined there was a significant combination benefit compared to either drug given alone. The DOHH-2 xenograft model of B-cell lymphoma was also sensitive to venetoclax (50mg/kg) and with a similar impact on tumour growth compared with CCS1477 (10mg/kg). In this model the combination of CCS1477 and venetoclax was more profound and caused complete tumour stasis during the dosing period. These data support the clinical testing of CCS1477 in combination with azacitidine and/or venetoclax in AML and B-cell lymphomas. CCS1477 is currently in Phase I/II clinical trials in AML, Non-Hodgkin lymphoma (including B-cell lymphoma) and multiple myeloma. (NCT04068597). Disclosures Brooks: CellCentric Ltd: Current Employment, Current holder of individual stocks in a privately-held company. Knurowski: CellCentric Ltd: Current Employment, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Hughes: CellCentric Ltd: Consultancy, Current holder of individual stocks in a privately-held company, Current holder of stock options in a privately-held company. Clegg: CellCentric Ltd: Current Employment, Current holder of individual stocks in a privately-held company. West: CellCentric Ltd: Current Employment, Current holder of individual stocks in a privately-held company. Pegg: CellCentric Ltd: Current Employment, Current holder of individual stocks in a privately-held company. Somervaille: Novartis: Consultancy, Honoraria.

Antineoplastic effects of erufosine on Graffi myeloid tumour in hamsters

Cancer has become one of the most significant health challenges for both human and veterinary medicine. The present study examined the antineoplastic and antimetastatic activity of the novel membrane-targeting anticancer agent erufosine. The antitumour effects of erufosine on Graffi virus-induced experimental myeloid tumour in hamsters was assessed by histopathological methods and evaluation of some biometric parameters of tumour growth. Two schemes of experimental antitumour therapy were applied - one that started simultaneously with the tumour transplantation and a second one that started after the appearance of palpable tumours. The results demonstrated protective antitumour effect of erufosine, expressed by decrease of transplantability, tumour growth inhibition, suppression of metastatic activity and extension of mean survival time. The effectivity of the experimental therapy was more pronounced when it was started simultaneously with the transplantation of the tumour cells. Presented results suggest that erufosine is a promising drug candidate for treatment of haematological malignances.

Monocytes mediate Salmonella Typhimurium-induced tumour growth inhibition

The use of bacteria as an alternative cancer therapy has been re-investigated in recent years. A number of bacterial strains for this purpose have been generated, one of which is SL7207: an auxotrophic Salmonella enterica serovar Typhimurium aroA mutant with immune-stimulatory potential. Here we show that systemic administration of SL7207 induces melanoma tumour growth arrest in vivo, with greater survival of the SL7207-treated group compared to control PBS-treated mice. Administration of SL7207 is accompanied by a change in the immune phenotype of the tumour-infiltrating cells towards pro-inflammatory, with expression of the TH1 cytokines IFN-γ, TNF-α, and IL-12 significantly increased. Interestingly, Ly6C+MHCII+ monocytes were recruited to the tumours following SL7207 treatment and were pro-inflammatory. Accordingly, the abrogation of these infiltrating monocytes using clodronate liposomes prevented SL7207-induced tumour growth inhibition. These data demonstrate a previously unappreciated role for infiltrating inflammatory monocytes underlying bacterial-mediated tumour growth inhibition. This information highlights a novel role for monocytes in controlling tumour growth, contributing to our understanding of the immune responses required for successful immunotherapy of cancer.

Translational analysis from SCALOP trial: CCL5 as a prognostic biomarker and a potentially actionable target in locally advanced pancreatic cancer (LAPC).

740 Background: SCALOP was a multi-centre phase II RCT where 114 patients with LAPC were received 3 cycles of Gemcitabine and Capecitabine (GEMCAP) and those with stable/responding disease (n = 74) were randomised to Gem-RT or Cap-RT. The trial showed superiority of Cap-RT. Baseline blood samples of randomised patients were analysed for 35 circulating biomarkers. In vivo study was undertaken with candidate biomarker (CCL5) to test actionability. Methods: Patient bloods were tested using R&D multiplexed magnetic Luminex assays and IGF-1, TGF-b1 and b-NGF DuoSet ELISA. Orthotropic KrasG12D;P53R172H;PDXcre (KPC) tumors were implanted in Bl6-mice and treated with Gem, CCR5-inhibitor (CCR5i) maraviroc (MV), PD1 inhibitor (PD1i), PD1i+MV alone and in combination with MRI guided small animal Radiotherapy (RT). Immunophenotyping was performed by IHC and Aurora Cytek spectral flow cytometry. Results: Baseline biomarker data was available on 63/74 randomised patients. Of the 35 biomarkers tested, only CCL5 was found to be significantly associated with OS with a median OS of 18.5 (95% CI: 11.76-21.32) vs 11.3 (9.86-15.51) months (low vs high), and HR 1.37 (95% CI:1.04-3.65; p = 0.037) in the Cox multivariable model. Treatment of orthotopic KPC tumors revealed that combination of MV+PD1i+RT resulted in tumour growth inhibition and a switch of tumour macrophages from M2 to M1 accompanied by increase in infiltration of cytotoxic CD8+ Tcells and NK cells. Conclusions: Previous pre-clinical studies reported CCL5-CCR5 axis as a poor prognostic marker and a possible cause of immune-resistance in pancreatic cancer. Herein we have demonstrated in prospectively collected clinical trial blood samples that high circulating CCL5 is associated with poor prognosis in LAPC. CCR5 inhibitor in combination with RT+PD1i may overcome immune-resistance, and should be tested in clinical trials. Clinical trial information: 96169987 .

Antitumour Property of Pterocarpus santalinus Seeds Against DMBA-Induced Breast Cancer in Rats

Breast cancer has been one of the most common form of malignancy globally among women, for more than a decade. Despite various preventive and treatment measures, it remains associated with high incidence and mortality rate. Pterocarpus santalinus Linn. f. has been extensively used in Indian medicine system Ayurveda, due to its various medicinal properties. However, despite various research works on the anticancer activity of P santalinus, no studies have been reported on animal model. Therefore, this study was aimed to decipher the antitumour activity of ethanolic seeds extract of P santalinus on DMBA (7,12-dimethylbenz(a)-anthracene)-induced breast cancer in rats. Fifty-five-days-old weighed (150 ± 10 g) female Charles Foster rats (12 females) were used for the study. The rats were divided into 3 groups of 4 rats each. 7,12-Dimethylbenz(a)-anthracene (single dose of 20 mg/mL dissolved in olive oil) was induced orally, to develop breast tumour. After the development of breast tumours (about 0.5 cm), the rats were treated with P santalinus ethanolic seeds extract (300 mg/kg body weight/day) orally for 5 weeks and then volume of tumour was measured. Oral administration of P santalinus extract resulted in about 49.5% tumour growth inhibition in the final week of treatment in DMBA + P santalinus group as compared with the DMBA group. Pterocarpus santalinus administration also significantly reduced ( P < .0001) the serum malondialdehyde level from 58.81 ± 4.09 nmol/mL in DMBA group to 10.87 ± 1.20 nmol/mL in the DMBA + P santalinus group. Serum tumour necrosis factor-α level reduced significantly ( P < .0001) from 80.43 ± 2.45 pg/mL in DMBA group to 28.30 ± 3.24 pg/mL in the DMBA + P santalinus group. The blood serum glucose level also reduced significantly ( P < .0001) from 205.9 ± 22.22 mg/dL in DMBA group to 86.44 ± 8.36 in DMBA + P santalinus group. There was significant ( P < .0001) improvement in the both the liver and kidney serum biomarkers level after P santalinus administration. The histological study of mammary tissues of rats shows that, in the DMBA group immature fibrocytes are completely replacing the normal adipocytes suggestive of fibroma molle, whereas in the DMBA + P santalinus group mature fibrocytes with multilayer glandular cells were seen denoting fibroadenoma. Thus, the P santalinus ethanolic seed extract possesses antitumorigenic, antioxidant and hypoglycaemic properties as well as hepato-renal protective effect. Hence, it may be concluded that P santalinus has therapeutic role against DMBA-induced breast cancer in rats and has a greater potential to develop as a chemotherapeutic agent in breast cancer treatment.

Novel dihydroartemisinin dimer containing nitrogen atoms inhibits growth of endometrial cancer cells and may correlate with increasing intracellular peroxynitrite

In the present study, a novel dimer, SM1044, selected from a series of dihydroartemisinin (DHA) derivatives containing nitrogen atoms comprising simple aliphatic amine linkers, showed strong growth inhibition in six types of human endometrial cancer (EC) cells, with half maximal inhibitory concentration (IC50) and 95% confidence interval (CI) < 3.6 (1.16~11.23) μM. SM1044 evoked apoptosis and activated caspase-3, −8 and −9 in a concentration- and time-dependent manner, and these effects were manifested early in RL95-2 compared to KLE cells, possibly correlated with the induction of intracellular ONOO−. Catalase and uric acid attenuated the growth inhibitory effects of SM1044 on EC cells, but sodium pyruvate did not. In vivo, the average xenograft tumour growth inhibition rates ranged from 35.8% to 49.9%, respectively, after 2.5 and 5.0 mg/kg SM1044 intraperitoneal treatment, and no obvious behavioural and histopathological abnormalities were observed in SM1044-treated mice in this context. SM1044 predominantly accumulated in the uteri of mice after a single injection. SM1044 displayed efficacy as a tumour suppressor with distinct mechanism of action and unique tissue distribution, properties that distinguish it from other artemisinin analogues. Our findings provide a new clue for artemisinin analogue against cancer.

Signalling involving MET and FAK supports cell division independent of the activity of the cell cycle-regulating CDK4/6 kinases

Deregulation of the cyclin-dependent kinases 4 and 6 (CDK4/6) is highly prevalent in cancer yet inhibitors against these kinases currently show use in restricted tumour contexts. The extent to which cancers depend on CDK4/6 and what may undermine such dependency is poorly understood. Here we report that signalling engaging the MET proto-oncogene receptor tyrosine kinase/focal adhesion kinase (FAK) axis leads to CDK4/6-independent CDK2-activation, involving as a critical mechanistic events loss of the CDK inhibitor p21CIP1 and gain of its regulator, the ubiquitin ligase subunit SKP2. Combined inhibition of MET/FAK and CDK4/6 eliminates proliferation capacity of cancer cells in culture, and enhances tumour growth inhibition in vivo. Activation of the MET/FAK axis is known to arise through cancer extrinsic and intrinsic cues. Our work predicts that such cues support cell division independent of the activity of the cell cycle-regulating CDK4/6 kinases and identifies MET/FAK as a tractable route to broaden the utility of CDK4/6 inhibitor-based therapies in the clinic.