OUP accepted manuscript

BACKGROUND

The antiangiogenic tyrosine kinase inhibitor regorafenib provides a survival benefit in patients with previously treated metastatic colorectal cancer (CRC). Antiangiogenic therapy causes hypoxic stress within tumor cells, which activates autophagy as a survival mechanism. The histone deacetylase inhibitor (HDAC) entinostat increases dependence on autophagy through epigenetic mechanisms. Hydroxychloroquine (HCQ) blocks autophagy by blunting lysosomal acidification. We hypothesized that HCQ and entinostat would be tolerable with regorafenib and potentiate the antitumor response.

METHODS

This was a 3+3 phase I trial of HCQ and entinostat with regorafenib in patients with metastatic CRC. The primary objective was safety, and the secondary objective was clinical efficacy.

RESULTS

Twenty patients received study therapy. Six evaluable patients were enrolled at each of the three planned dose levels, one patient at an intermediate dose level, and one additional patient withdrew consent after 4 days to receive treatment closer to home. One dose-limiting toxicity was noted in the study at dose level 2 (grade 3 fatigue). Seven patients discontinued therapy due to related toxicities; rapid weight loss was near universal, with a median weight loss of 4.4 kg (range 1.5-12.2 kg) in the first 2 weeks of treatment. No objective responses were observed.

CONCLUSION

The combination of regorafenib, HCQ, and entinostat was poorly tolerated without evident activity in metastatic CRC.

CLINICALTRIALS.GOV IDENTIFIER

NCT03215264.

Phase I trial of regorafenib, hydroxychloroquine, and entinostat in metastatic colorectal cancer

e15580

Background: The antiangiogenic tyrosine kinase inhibitor regorafenib provides a survival benefit in patients with previously treated metastatic colorectal cancer. Antiangiogenic therapy causes hypoxic stress within tumor cells, which activate autophagy as a survival mechanism. Entinostat, a histone deacetylase (HDAC) inhibitor, increases dependence on autophagy through epigenetic mechanisms. Hydroxychloroquine (HCQ) blocks autophagy by blunting lysosomal acidification and is synergistic with antiangiogenic therapies. We hypothesized that HCQ and entinostat would be tolerable with regorafenib and potentiate the antitumor response. Methods: This was a 3+3 phase I trial to find the recommended phase II dose (RP2D) of HCQ and entinostat with regorafenib in patients with metastatic colorectal cancer previously treated with a fluoropyrimidine, oxaliplatin, and irinotecan. No prior regorafenib or HDAC inhibitor therapy was permitted. Regorafenib was dosed at 160mg daily on days 1-21 of 28-day cycles, with provision to lower the starting dose to 80mg if toxicity was excessive. Entinostat was dosed at 3mg weekly in dose level 1 and at 5mg weekly in dose levels 2 and 3 while HCQ was dosed at 200mg qAM and 400mg qPM in dose levels 1 and 2 and at 600mg BID at dose level 3. Expansion was planned at the RP2D with a primary endpoint of objective response rate. Results: Twenty-eight patients were screened, and 20 patients were enrolled from November 2017 to January 2020. Six patients were treated at dose level 1 with no dose-limiting toxicity. The starting regorafenib dose was reduced to 80mg after 3 patients discontinued therapy early due to fatigue or rash due to regorafenib. At dose level 2, 7 patients were enrolled to achieve 6 evaluable patients. One DLT (G3 fatigue) was noted and one patient withdrew consent after 14 days due to fever and tumor pain flare possibly related to treatment. Six patients enrolled at dose level 3; no DLTs were seen. One additional patient received HCQ 400mg BID instead of 600mg BID due to a clerical error. Weight loss (60%), fatigue (50%), and anorexia (50%) were the most common toxicities. Thirteen grade 3 toxicities were noted, with rash (15%), fatigue (10%), and alkaline phosphatase elevation (10%) the most common. No grade 4 toxicities were observed. Seven patients discontinued therapy early due to toxicity. Nearly all patients experienced rapid weight loss, with a range of 1.5 lbs to 27.1 lbs and a median weight loss of 9.5 lbs at two weeks. No objective responses were observed. The median PFS was 1.8 months, the median OS was 5.2 months, and no patient remained on study longer than 4 months. Expansion was not pursued due to toxicity and lack of efficacy. Conclusions: The combination of regorafenib, HCQ, and entinostat was poorly tolerated without evident activity in metastatic colorectal cancer. The substantial weight loss suggests a potential adverse metabolic interaction between these drugs. Clinical trial information: NCT03215264.

A Pilot Study of Galunisertib plus Stereotactic Body Radiotherapy in Patients with Advanced Hepatocellular Carcinoma

TGFβ is a pleiotropic cytokine with immunosuppressive activity. In preclinical models, blockade of TGFβ enhances the activity of radiation and invokes T-cell antitumor immunity. Here, we combined galunisertib, an oral TGFβ inhibitor, with stereotactic body radiotherapy (SBRT) in patients with advanced hepatocellular carcinoma (HCC) and assessed safety, efficacy, and immunologic correlatives. Patients (n = 15) with advanced HCC who progressed on, were intolerant of, or refused sorafenib were treated with galunisertib (150 mg orally twice a day) on days 1 to 14 of each 28-day cycle. A single dose of SBRT (18-Gy) was delivered between days 15 to 28 of cycle 1. Site of index lesions treated with SBRT included liver (9 patients), lymph node (4 patients), and lung (2 patients). Blood for high-dimensional single cell profiling was collected. The most common treatment-related adverse events were fatigue (53%), abdominal pain (46.6%), nausea (40%), and increased alkaline phosphatase (40%). There were two instances of grade 2 alkaline phosphatase increase and two instances of grade 2 bilirubin increase. One patient developed grade 3 achalasia, possibly related to treatment. Two patients achieved a partial response. Treatment with galunisertib was associated with a decrease in the frequency of activated T regulatory cells in the blood. Distinct peripheral blood leukocyte populations detected at baseline distinguished progressors from nonprogressors. Nonprogressors also had increased CD8⁺PD-1⁺TIGIT⁺ T cells in the blood after treatment. We found galunisertib combined with SBRT to be well tolerated and associated with antitumor activity in patients with HCC. Pre- and posttreatment immune profiling of the blood was able to distinguish patients with progression versus nonprogression.

Peripheral blood immune correlates associated with TGF-β inhibition (galunisertib) and stereotactic body radiotherapy (SBRT) in patients with advanced hepatocellular carcinoma (HCC)

4575

Background: TGF-β is a pleiotropic cytokine with immunosuppressive activity. In mouse models, blockade of TGF-β signaling enhances the activity of radiation and invokes T cell dependent anti-tumor immunity. We previously reported preliminary safety and efficacy results from a pilot study combining galunisertib (LY2157299), an oral TGF-β inhibitor, with SBRT for the treatment of patients with advanced HCC. Here, we investigate immunological mechanisms and potential biomarkers associated with therapeutic activity. Methods: Patients with advanced HCC who had progressed on or refused sorafenib were treated with galunisertib (150 mg PO BID) on days 1-14 of each 28-day cycle. SBRT (18 Gy) was delivered in a single dose between days 15-28 of cycle 1. Blood was collected at baseline, following two weeks of galunisertib and following SBRT for high-dimensional analysis using a 37-marker CyTOF panel. Patients were dichotomized based on best response as either progressor (PD) or non-progressor (PR+SD). The frequency of immune subsets was compared between groups. Results: Fifteen patients were enrolled and treated. One patient was not evaluable. The most common adverse event was grade 1 or 2 fatigue in 53% of patients. The only possibly-related grade 3 event was achalasia in one patient which coincided with disease progression. Two patients achieved a PR and six patients had SD (DCR 57%) with a median progression-free survival of 3.7 months and a median overall survival of 9.0 months. For most patients, regardless of outcome, galunisertib treatment was associated with a decrease in activated Ki67+ Treg cells. However, pre-treatment immune composition within the blood of progressors and non-progressors was distinct. At baseline, progressors had an increased frequency of naive-like CD8+ T cells, whereas non-progressors had an increased frequency of non-classical monocytes. After combination therapy, only non-progressors showed a significant increase in CD8+PD1+TIGIT+ T cells. Conclusions: Galunisertib combined with SBRT was well-tolerated with modest efficacy. Immune profiling of the blood revealed distinct pre- and post-treatment signatures that differentiated patients with progression versus non-progression. These findings show that the combination of anti-TGF-β therapy with radiation can mediate disease control and identify potential correlates of efficacy. Clinical trial information: NCT02906397 .