The lysosomal degradation pathway known as autophagy has an essential homeostatic role in controlling the quality of the cytoplasm. However, this pathway has also been implicated in the pathology of an array of human disorders. Here, Rubinsztein and colleagues provide an overview of the mechanisms and regulation of autophagy, discuss the role of this pathway in disease and highlight potential strategies for therapeutic modulation.

/pdf/autophagy-modulation-as-a-potential-therapeutic-target-for-2jy1kcxaer.pdf

Autophagy modulation as a potential therapeutic target for diverse diseases

Activation of oncogenes and loss of tumour suppressors promote metabolic reprogramming in cancer, resulting in enhanced nutrient uptake to supply energetic and biosynthetic pathways. However, nutrient limitations within solid tumours may require that malignant cells exhibit metabolic flexibility to sustain growth and survival. Here, we highlight these adaptive mechanisms and also discuss emerging approaches to probe tumour metabolism in vivo and their potential to expand the metabolic repertoire of malignant cells even further.

/pdf/metabolic-pathways-promoting-cancer-cell-survival-and-growth-47qi2j2b8h.pdf

Metabolic pathways promoting cancer cell survival and growth.

Autophagy, as a type II programmed cell death, plays crucial roles with autophagy-related (ATG) proteins in cancer. Up to now, the dual role of autophagy both in cancer progression and inhibition remains controversial, in which the numerous ATG proteins and their core complexes including ULK1/2 kinase core complex, autophagy-specific class III PI3K complex, ATG9A trafficking system, ATG12 and LC3 ubiquitin-like conjugation systems, give multiple activities of autophagy pathway and are involved in autophagy initiation, nucleation, elongation, maturation, fusion and degradation. Autophagy plays a dynamic tumor-suppressive or tumor-promoting role in different contexts and stages of cancer development. In the early tumorigenesis, autophagy, as a survival pathway and quality-control mechanism, prevents tumor initiation and suppresses cancer progression. Once the tumors progress to late stage and are established and subjected to the environmental stresses, autophagy, as a dynamic degradation and recycling system, contributes to the survival and growth of the established tumors and promotes aggressiveness of the cancers by facilitating metastasis. This indicates that regulation of autophagy can be used as effective interventional strategies for cancer therapy.

https://link.springer.com/content/pdf/10.1186/s12943-020-1138-4.pdf

Autophagy and autophagy-related proteins in cancer

https://digital.csic.es/bitstream/10261/135784/1/novel%20therapeutic%20targets.pdf

Sustained proliferation in cancer: Mechanisms and novel therapeutic targets

Autophagy: The spotlight for cellular stress responses.

Autophagy is a homeostatic, catabolic degradation process whereby cellular proteins and organelles are engulfed into autophagosomes, digested in lysosomes and recycled to sustain cellular metabolism. Autophagy has dual roles in cancer, acting as both a tumor suppressor by preventing the accumulation of damaged proteins and organelles and as a mechanism of cell survival that can promote the growth of established tumors. Tumor cells activate autophagy in response to cellular stress including hypoxia and increased metabolic demands related to rapid cell proliferation. Autophagy-related stress tolerance can enable cell survival by maintaining energy production that can lead to tumor growth and therapeutic resistance, as shown in preclinical models where the inhibition of autophagy can restore chemosensitivity and enhance tumor cell death. These results established autophagy as a therapeutic target and have led to multiple early phase clinical trials in humans evaluating autophagy inhibition using hydroxychloroquine in combination with chemotherapy or targeted agents. Targeting autophagy in cancer provides new opportunities for drug development since more potent and specific inhibitors of autophagy are needed. The role of autophagy and its regulation in cancer cells continues to emerge and studies aim to define optimal strategies to modulate autophagy for therapeutic advantage.

/pdf/the-role-of-autophagy-in-cancer-therapeutic-implications-2i3ydfb9ti.pdf

The role of autophagy in cancer: therapeutic implications.

Autophagy is a homeostatic and catabolic process that enables the sequestration and lysosomal degradation of cytoplasmic organelles and proteins that is important for the maintenance of genomic stability and cell survival. Beclin 1+/− gene knockout mice are tumor prone, indicating a tumor suppressor role for autophagy. Autophagy is also a mechanism of stress tolerance that maintains cell viability and can lead to tumor dormancy, progression and therapeutic resistance. Many anticancer drugs induce cytotoxic stress that can activate pro-survival autophagy. In some contexts, excessive or prolonged autophagy can lead to tumor cell death. Inhibition of cytoprotective autophagy by genetic or pharmacological means has been shown to enhance anticancer drug-induced cell death, suggesting a novel therapeutic strategy. Studies are ongoing to define optimal strategies to modulate autophagy for cancer prevention and therapy, and to exploit it as a target for anticancer drug discovery.

Autophagy modulation for cancer therapy

https://www.gastro.theclinics.com/article/S0889-8553(10)00059-2/pdf

Targeted Therapeutic Agents for Colorectal Cancer

Abstract Background Hepatocellular carcinoma (HCC) remains difficult to treat due to limited effective treatment options. While the proteasome inhibitor bortezomib has shown promising preclinical activity in HCC, clinical trials of bortezomib showed no advantage over the standard-of-care treatment sorafenib, highlighting the need for more clinically relevant therapeutic strategies. Here, we propose that rational drug combination design and validation in patient-derived HCC avatar models such as patient-derived xenografts (PDXs) and organoids can improve proteasome inhibitor-based therapeutic efficacy and clinical potential. Methods HCC PDXs and the corresponding PDX-derived organoids (PDXOs) were generated from primary patient samples for drug screening and efficacy studies. To identify effective proteasome inhibitor-based drug combinations, we applied a hybrid experimental-computational approach, Quadratic Phenotypic Optimization Platform (QPOP) on a pool of nine drugs comprising proteasome inhibitors, kinase inhibitors and chemotherapy agents. QPOP utilizes small experimental drug response datasets to accurately identify globally optimal drug combinations. Results Preliminary drug screening highlighted the increased susceptibility of HCC PDXOs towards proteasome inhibitors. Through QPOP, the combination of second-generation proteasome inhibitor ixazomib (Ixa) and CDK inhibitor dinaciclib (Dina) was identified to be effective against HCC. In vitro and in vivo studies demonstrated the synergistic pro-apoptotic and anti-proliferative activity of Ixa + Dina against HCC PDXs and PDXOs. Furthermore, Ixa + Dina outperformed sorafenib in mitigating tumor formation in mice. Mechanistically, increased activation of JNK signaling mediates the combined anti-tumor effects of Ixa + Dina in HCC tumor cells. Conclusions Rational drug combination design in patient-derived avatars highlights the therapeutic potential of proteasome and CDK inhibitors and represents a feasible approach towards developing more clinically relevant treatment strategies for HCC. 

/pdf/rational-drug-combination-design-in-patient-derived-avatars-23vgy72b.pdf

Rational drug combination design in patient-derived avatars reveals effective inhibition of hepatocellular carcinoma with proteasome and CDK inhibitors

1574 Background: Most treatment guidelines recommend chemotherapy at maximum tolerated doses, which does not always lead to optimal efficacy, but implicitly results in toxicity. To overcome this challenge, we developed CURATE.AI, a small data, AI-derived platform that harnesses only a patient’s own prospectively/longitudinally acquired data to dynamically identify their own optimal and personalized doses. We subsequently harnessed CURATE.AI to dynamically modulate individualized chemotherapy doses for patients in a prospective clinical trial. Methods: We conducted an open-label, multi-center, single-arm, prospective feasibility trial in patients diagnosed with advanced solid tumors and treated with single-agent capecitabine, XELOX or XELIRI (+/- biologics) (NCT04522284). The standard-of-care (SOC) capecitabine dose was 1000 mg/m2, unless adjusted by clinician to account for patient’s comorbidities and organ dysfunction. Using an AI-discovered second-order correlation between patient-specific variation of capecitabine doses and corresponding tumor marker (CEA, CA19-9 or CA-125) readouts for each cycle, CURATE.AI generated individualized patient digital avatars and recommended bespoke dose for the subsequent cycle. The clinicians were permitted to accept CURATE.AI dose recommendations, or reject the recommendations and dose based on clinical judgement. Results: Since August 2020 we recruited ten patients: single-agent capecitabine (n = 1), XELOX (n = 6), and XELIRI (n = 3). As of 20 Jan 2022, one patient remains on the trial. The prescribed dose was on average reduced by 20 % (± 13.8 %) as compared to the projected SOC dose. The nine reported patients completed 3.9 cycles (± 2.2 cycles), with the longest participation lasting 8 cycles. CURATE.AI recommendations were considered in 27 out of 40 total dosing decisions and accepted for prescription in 26 of those decisions. The reasons for not considering CURATE.AI included insufficient time from patient recruitment to the first dose administration and complex medical circumstances at the time of the dosing decisions. Conclusions: CURATE.AI has been successfully incorporated into the clinical workflow of dynamic dose selection in the treatment of solid tumors under a clinical trial. Prospective validation of CURATE.AI led to a reduction of an average prescribed capecitabine dose, which alongside additional preliminary findings may eventually play an important role in improving patient response rates and durations compared to SOC. Results from the PRECISE CURATE.AI trial support the initiation of a randomized clinical trial and potential expansion towards other oncologic indications. Clinical trial information: NCT04522284.

Cheng E. Chee

Papers

The role of autophagy in cancer: therapeutic implications.

Autophagy modulation for cancer therapy

Targeted Therapeutic Agents for Colorectal Cancer

Rational drug combination design in patient-derived avatars reveals effective inhibition of hepatocellular carcinoma with proteasome and CDK inhibitors

PRECISE CURATE.AI: A prospective feasibility trial to dynamically modulate personalized chemotherapy dose with artificial intelligence.