Should we move beyond VEGF inhibition in metastatic colorectal cancer? Lessons from early phase clinical trials

Modulation of autophagy: a Phase II study of vorinostat plus hydroxychloroquine versus regorafenib in chemotherapy-refractory metastatic colorectal cancer (mCRC)

BACKGROUND

In metastatic colorectal cancer (mCRC), regorafenib (RGF), a multi-kinase inhibitor with angiogenic inhibition has modest effects on survival. We reported that autophagy modulation using hydroxychloroquine (HCQ), enhances the anticancer activity of the histone deacetylase inhibitor, vorinostat (VOR), in mCRC, is well tolerated, and has comparable activity to RGF. Thus, we conducted a prospective study of VOR/HCQ versus RGF in mCRC.

METHODS

This is a randomised, controlled trial of VOR 400 mg and HCQ 600 mg orally daily versus RGF 160 mg orally daily (3 weeks on/1 week off), every 4 weeks, in patients with mCRC.

PRIMARY ENDPOINT

median progression-free survival (mPFS). Secondary endpoints: median overall survival (mOS); adverse events; pharmacodynamic analyses.

RESULTS

From 2/2015-10/2017, 42 patients were randomised to VOR/HCQ and RGF. Median age was 58.4 years. mPFS on VOR/HCQ was 1.9 months versus 4.35 months with RGF (P = 0.032). There was no difference in mOS (P = 0.9). Treatment was tolerated in both arms. In both arms, there was improved anti-tumour immunity.

CONCLUSIONS

VOR/HCQ had an inferior PFS when compared to RGF, although there was an increase in anti-tumour immunity in mCRC. VOR/HCQ has a favourable safety profile, and immune or tumour biomarkers may be used to identify clinical benefit of autophagy modulation in mCRC.

CLINICAL TRIAL REGISTRATION

NCT02316340.

Stroma-derived HGF drives metabolic adaptation of colorectal cancer to angiogenesis inhibitors

The role of paracrine Hepatocyte Growth Factor (HGF) in the resistance to angiogenesis inhibitors (AIs) is hidden in xenograft models because mouse HGF fails to fully activate human MET. To uncover it, we compared the efficacy of AIs in wild-type and human HGF knock-in SCID mice bearing orthotopic human colorectal tumors. Species-specific HGF/MET signaling dramatically impaired the response to anti-angiogenic agents and boosted metastatic dissemination. In cell-based assays mimicking the consequences of anti-angiogenic therapy, colorectal cancer cells were completely resistant to hypoxia but extremely sensitive to nutrient deprivation. Starvation-induced apoptosis could be prevented by HGF, which promoted GLUT1-mediated glucose uptake, sustained glycolysis and activated autophagy. Pharmacological inhibition of GLUT1 in the presence of glucose killed tumor cells as effectively as glucose deprivation, and this effect was antagonized by HGF. Concomitant targeting of GLUT1 and HGF potently suppressed growth and dissemination of AI-resistant human tumors in human HGF knock-in SCID mice without exacerbating tumor hypoxia. These data suggest that stroma-derived HGF protects CRC cells against glucose starvation-induced apoptosis, promoting resistance to both AIs and anti-glycolytic agents. Combined inhibition of glucose metabolism and HGF/MET signaling (‘anti-METabolic therapy’) may represent a more effective CRC treatment compared to utterly blocking tumor blood supply.

Immunotherapy in colorectal cancer: for the select few or all?

Over the past few years, the role of immunotherapy in colorectal cancer (CRC) has expanded, specifically in subsets of CRC with microsatellite instability (MSI) for which newer agents, such as programmed death-1 (PD-1) inhibitors, are efficacious. While other immunotherapeutic agents are more immature in development, they have the potential to enhance the efficacy of PD-1 inhibitors and play a role in the treatment algorithm for all subsets of CRC patients. In this review, we will discuss immunotherapeutic agents in development in patients with CRC. We will review the later phase studies that elucidate the role of immunotherapy in CRC and provide hope for changing the treatment paradigm for CRC in the future.

Vorinostat and hydroxychloroquine improve immunity and inhibit autophagy in metastatic colorectal cancer

Hydroxychloroquine (HCQ) enhances the anti-cancer activity of the histone deacetylase inhibitor, vorinostat (VOR), in pre-clinical models and early phase clinical studies of metastatic colorectal cancer (mCRC). Mechanisms could include autophagy inhibition, accumulation of ubiquitinated proteins, and subsequent tumor cell apoptosis. There is growing evidence that autophagy inhibition could lead to improved anti-cancer immunity. To date, effects of autophagy on immunity have not been reported in cancer patients. To address this, we expanded an ongoing clinical study to include patients with advanced, refractory mCRC to evaluate further the clinical efficacy and immune effects of VOR plus HCQ. Refractory mCRC patients received VOR 400 milligrams orally with HCQ 600 milligrams orally daily, in a 3-week cycle. The primary endpoint was median progression-free survival (mPFS). Secondary endpoints include median overall survival (mOS), adverse events (AE), pharmacodynamic of inhibition of autophagy in primary tumors, immune cell analyses, and cytokine levels. Twenty patients were enrolled (19 evaluable for survival) with a mPFS of 2.8 months and mOS of 6.7 months. Treatment-related grade 3-4 AEs occurred in 8 patients (40%), with fatigue, nausea/vomiting, and anemia being the most common. Treatment significantly reduced CD4+CD25hiFoxp3+ regulatory and PD-1+ (exhausted) CD4+ and CD8+ T cells and decreased CD45RO-CD62L+ (naive) T cells, consistent with improved anti-tumor immunity. On-study tumor biopsies showed increases in lysosomal protease cathepsin D and p62 accumulation, consistent with autophagy inhibition. Taken together, VOR plus HCQ is active, safe and well tolerated in refractory CRC patients, resulting in potentially improved anti-tumor immunity and inhibition of autophagy.