Evorpacept alone and in combination with pembrolizumab or trastuzumab in patients with advanced solid tumours (ASPEN-01): a first-in-human, open-label, multicentre, phase 1 dose-escalation and dose-expansion study

BACKGROUND

Both innate and adaptive immune responses are important components of anticancer immunity. The CD47-SIRPα interaction could represent an important pathway used by tumour cells to evade immune surveillance. We aimed to evaluate the safety, pharmacokinetics, pharmacodynamics, and anticancer activity of evorpacept (also known as ALX148), a high-affinity CD47-blocking protein with an inactive IgG Fc region in patients with solid tumours.

METHODS

We did a first-in-human, open-label, multicentre, phase 1 dose-escalation and dose-expansion study at nine hospitals and one clinic in the USA and Korea. Eligible patients for the dose-escalation and safety lead-in phases were aged 18 years or older with histological or cytological diagnosis of advanced or metastatic solid tumours with no available standard therapy, measurable or unmeasurable disease according to the Response Evaluation Criteria in Solid Tumors version 1.1, and an Eastern Cooperative Oncology Group performance status score of 0 or 1. In the dose-escalation phase, which used a 3 + 3 design, patients received intravenous evorpacept at either 0·3, 1, 3, or 10 mg/kg once per week in 21-day cycles, or 30 mg/kg once every other week in 28-day cycles. In the safety lead-in phase, patients were given the maximum tolerable dose of evorpacept from the dose-escalation phase plus either intravenous pembrolizumab (200 mg administered once every 3 weeks) or intravenous trastuzumab (8 mg/kg loading dose followed by 6 mg/kg once every 3 weeks). In the dose-expansion phase, additional patients aged 18 years or older with second-line or later-line advanced malignancies were enrolled into three parallel cohorts: those with head and neck squamous cell carcinoma (HNSCC) and those with non-small-cell lung cancer (NSCLC) were given the maximum tolerated dose of evorpacept plus intravenous pembrolizumab (200 mg administered once every 3 weeks), and patients with HER2-positive gastric or gastroesophageal junction cancer were given the maximum tolerated dose of evorpacept plus intravenous trastuzumab (8 mg/kg loading dose followed by 6 mg/kg once every 3 weeks) until disease progression, voluntary withdrawal from the study, or unacceptable toxicity. The primary endpoint was the maximum tolerated dose of evorpacept administered as a single agent and in combination with pembrolizumab or trastuzumab, measured by the occurrence of dose-limiting toxicities during the first cycle, and was assessed in all patients who had received at least one dose of evorpacept. Secondary outcomes included the safety, tolerability, and antitumour activity of evorpacept, alone or in combination with pembrolizumab or trastuzumab. The primary outcome, safety, and tolerability were assessed in all patients who had received at least one dose of evorpacept, and antitumour activity was assessed in those who recieved at least one dose of study treatment and underwent at least one post-baseline tumor assessment. This trial is registered with ClinicalTrials.gov, NCT03013218.

FINDINGS

Between March 6, 2017, and Feb 21, 2019, 110 patients received single-agent evorpacept (n=28), evorpacept plus pembrolizumab (n=52), or evorpacept plus trastuzumab (n=30), and were included in the safety analysis. Median follow-up was 29·1 months (95% CI not calculable [NC]-NC) in the single-agent cohort, 27·0 months (25·1-28·8) in the evorpacept plus pembrolizumab cohort, and 32·7 months (27·0-32·7) in the evorpacept plus trastuzumab cohort. Two (7%) dose-limiting toxicities in the first cycle were reported in patients who received single-agent evorpacept; neutropenia with an associated infection in one patient with gastroesophageal junction cancer who received 3 mg/kg once per week, and thrombocytopenia with associated bleeding in one patient with pancreatic cancer who received 30 mg/kg once every other week. No maximum tolerated dose was reached; the maximum administered doses were 10 mg/kg once per week or 30 mg/kg once every other week. The 10 mg/kg once per week dose was used in the expansion cohorts in combination with pembrolizumab or trastuzumab. The most common grade 3 or worse treatment-related adverse events were thrombocytopenia with single-agent evorpacept (two [7%] patients) and evorpacept plus pembrolizumab (two [4%]), and thrombocytopenia (two [7%]) and neutropenia (two [7%]) with evorpacept plus trastuzumab. In patients who received single-agent evorpacept, four treatment-related serious adverse events were reported. Five serious treatment-related adverse events related to evorpacept plus pembrolizumab were reported, and one serious adverse event related to evorpacept plus trastuzumab was reported. In response-evaluable patients in the dose-escalation phase (n=15) receiving single-agent evorpacept once per week, four (27%) had a best overall response of stable disease (two received 0·3 mg/kg, one received 3 mg/kg, and one received 10 mg/kg); in the 11 patients who received single-agent evorpacept at the highest dose of 30 mg/kg once every other week, two (18%) had stable disease. In the dose-expansion cohort, overall responses were recorded in four (20·0%; 95% CI 5·7-43·7) of 20 patients with HNSCC who received evorpacept plus pembrolizumab, in one (5·0%; 0·1-24·9) of 20 patients with NSCLC who received evorpacept plus pembrolizumab, and in four (21·1%; 6·1-45·6) of 19 patients with gastric or gastroesophageal junction cancer who received evorpacept plus trastuzumab.

INTERPRETATION

The safety findings support the use of evorpacept in combination with pembrolizumab or trastuzumab for patients with advanced solid tumours. Preliminary antitumour activity results support future investigation of evorpacept combined with pembrolizumab or trastuzumab in patients with HNSCC, gastric or gastroesophageal junction cancer, and NSCLC.

FUNDING

ALX Oncology.

Neoadjuvant treatment of localized pancreatic adenocarcinoma

Pancreatic adenocarcinoma is one of the deadliest malignancies worldwide and its incidence is rising in the United States. The only potential curative treatment for this disease is surgical resection, however, due to the lack of an effective screening strategy, the majority of patients present with advanced or metastatic disease which preclude resectability. Further, the best clinical outcomes occur in those patients that receive multimodality treatment with surgical resection combined with chemotherapy with or without the addition of radiation therapy. Despite decades of innovation in treatment modalities, including chemotherapy, radiation therapy and advancements in surgical techniques, the long term outcomes for this disease remain poor with high rates of both local and distant recurrence despite curative intent treatment. The dismal outcomes of this disease highlight the dire need for more effective treatment strategies and therapeutics. This review focuses on the treatment of localized pancreatic adenocarcinoma with an in depth review of the literature to support the use of chemotherapy in the adjuvant and neoadjuvant setting in this disease and exploration and discussion of the growing paradigm shift to neoadjuvant treatment. Further, this review highlights the ongoing and planned clinical trials evaluating neoadjuvant treatment strategies and novel therapeutics in localized pancreatic adenocarcinoma.

Impact of neoadjuvant chemotherapy and stereotactic body radiation therapy (SBRT) on R0 resection rate for borderline resectable and locally advanced pancreatic cancer

BACKGROUND

The role of neoadjuvant stereotactic body radiation therapy (SBRT) in patients with borderline resectable pancreas cancer (BRPC) and locally advanced pancreas cancer (LAPC) remains controversial.

METHODS

We retrospectively evaluated BRPC and LAPC patients treated at our institution who underwent 2-3 months of chemotherapy followed by SBRT to a dose of 30-33 Gy. Overall survival (OS) and recurrence-free survival (RFS) were estimated and compared by Kaplan-Meier and log-rank methods.

RESULTS

We identified 103 (85 BRPC and 18 LAPC) patients treated per our neoadjuvant paradigm between 2011 and 2018, with resectability based on NCCN definitions. Median follow up was 25 months. Of patients completing neoadjuvant therapy, 73 (71%) underwent definitive resection. Seventy-one (97%) patients with definitively resected tumors had R0 resection and 5 (7%) had a complete pathologic response CR to neoadjuvant therapy. The median overall survival (OS) of the cohort was 24 months. Those with a complete or marked pathologic response had significantly better OS than those with a moderate response (41 vs 24 months, p < 0.02) and patients unable to undergo definitive surgery (17 months, p < 0.0003). Six resected patients experienced grade ≥3 surgical complications.

CONCLUSIONS

Neoadjuvant chemotherapy and SBRT are associated with promising pathologic response rates and R0 resection rates, with acceptable perioperative morbidity.

Outcome of neoadjuvant treatment for pancreatic cancer in elderly patients: comparative, observational cohort study

BACKGROUND

Use of neoadjuvant therapy for elderly patients with pancreatic cancer has been debatable. With FOLFIRINOX (folinic acid, 5-fluorouracil, irinotecan, oxaliplatin) or gemcitabine plus nab-paclitaxel (GnP) showing tremendous effects in improving the overall survival of patients with borderline resectable and locally advanced pancreatic cancer, there is no definitive consensus regarding the use of this regimen in the elderly.

METHODS

This study evaluated the eligibility of elderly patients with borderline resectable or locally advanced pancreatic cancer for neoadjuvant therapy. Patients registered in the database of pancreatic cancer at the University of Colorado Cancer Center, who underwent neoadjuvant treatment between January 2011 and March 2019, were separated into three age groups (less than 70, 70-74, 75 or more years) and respective treatment outcomes were compared.

RESULTS

The study included 246 patients with pancreatic cancer who underwent neoadjuvant treatment, of whom 154 and 71 received chemotherapy with FOLFIRINOX and GnP respectively. Among these 225 patients, 155 were younger than 70 years, 36 were aged 70-74 years, and 34 were aged 75 years or older. Patients under 70 years old received FOLFIRINOX most frequently (124 of 155 versus 18 of 36 aged 70-74 years, and 12 of 34 aged 75 years or more; P < 0.001). Resectability was similar among the three groups (60.0, 58.3, and 55.9 per cent respectively; P = 0.919). Trends towards shorter survival were observed in the elderly (median overall survival time 23.6, 18.0, and 17.6 months for patients aged less than 70, 70-74, and 75 or more years respectively; P = 0.090). After adjusting for co-variables, age was not a significant predictive factor.

CONCLUSION

The safety and efficacy of multiagent chemotherapy in patients aged 75 years or over were similar to those in younger patients. Modern multiagent regimens could be a safe and viable treatment option for clinically fit patients aged at least 75 years.

Tissue tumor mutational burden (TMB) as a biomarker of efficacy with immune checkpoint inhibitors (ICI) in metastatic gastrointestinal (mGI) cancers

e14559

Background: While TMB is very dependent on methodology, tissue TMB-H (≥10 mutations/megabase) may predict benefit with ICIs. Pembrolizumab received tissue-agnostic approval for TMB-H unresectable cancers in 2020, but little is known about TMB as a predictive biomarker in mGI cancers. We hypothesized that tissue TMB will correlate with efficacy of ICIs in mGI cancers. Methods: A retrospective chart review identified patients with mGI cancers who received an anti-PD-(L)1 drug and had known TMB at a single academic center from 2012 to 2020. The association of TMB with objective response rate (ORR), progression-free survival (PFS), and overall survival (OS) was analyzed using the Fisher’s exact and Log-rank tests. Survival curves were generated using the Kaplan-Meier method. Cox proportional hazard and logistic regression models were used to adjust for microsatellite status. Significance was prespecified at 0.05. Results: 83 patients were identified and included. The most common cancer types were colorectal adenocarcinoma (AC, n = 29), esophageal/gastric AC (n = 21) and SCC (n = 4), cholangiocarcinoma (n = 11), anal SCC (n = 7), and pancreas AC (n = 7). Average age was 61, average number of lines of prior systemic therapy for advanced disease was 1.3 (range 0-4), and 37% of patients were treated on a clinical study. All patients received an anti-PD-(L)1 drug; 6%, 2%, and 36% also received ipilimumab, cytotoxic chemotherapy, and other combinations, respectively. Among those with esophageal/gastric cancer, 76% had known PD-L1 CPS (84% ≥1, 63% ≥5, 42% ≥10). TMB was primarily determined by Foundation One CDx (87%). TMB ranged from 0 to 54; n = 22 (27%) were TMB-H (of these, n = 10 were microsatellite instability-high (MSI-H)), and n = 61 were TMB-L ( < 10 mutations/megabase; of these, n = 2 were MSI-H). The prevalence of TMB-H and microsatellite stable (MSS) was 14.4%. TMB-L, compared to TMB-H, was associated with inferior ORR (3.5% vs 55.6%; odds ratio (OR) 0.045; p < 0.001) and PFS (median 12.7 vs 29.3 weeks; hazard ratio (HR) 2.70; p = 0.001), but not OS (HR 1.20; p = 0.60). In patients with MSS disease, TMB-L, compared to TMB-H, was associated with inferior ORR (OR 0.13; p = 0.04) but not PFS (HR 1.76; p = 0.07) or OS (HR 0.89; p = 0.79). In subgroup analyses, ORR was not significantly associated to tumor type in all or MSS patients. TMB as a continuous variable, in patients with MSS disease, was positively correlated with ORR (p = 0.02) and PFS (p = 0.04), but not OS (p = 0.59). Among all patients, PFS and OS data is immature (median follow-up 13 and 31 weeks). Conclusions: In a single center retrospective study of patients with mGI cancers treated with ICIs, TMB-H was associated with improved ORR and PFS compared to TMB-L. In patients with MSS disease, ORR remained significant. PFS and OS data are immature. TMB as a biomarker of efficacy with ICIs in mGI cancers warrants further study to guide clinical use.

Utility of chemotherapy given before and/or after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy for appendiceal adenocarcinoma with peritoneal metastases

e16276

Background: Appendiceal adenocarcinoma is relatively rare and often diagnosed incidentally during operations for acute appendicitis. It is commonly associated, either at time of initial presentation or upon recurrence, with peritoneal metastases. A typical treatment strategy for patients with peritoneal disease includes cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC). Extrapolating largely from literature in colorectal cancer, chemotherapy is frequently given before and/or after CRS/HIPEC though high-level evidence to support this is lacking. We sought to evaluate the effect of systemic chemotherapy on survival. Methods: Utilizing a database of CRS/HIPEC procedures at University of Colorado Hospital from 2008 to present we retrospectively reviewed cases of appendiceal adenocarcinoma. Data collected included staging, histologic grade, chemotherapy given, surgical outcomes, and time to disease recurrence. Patients without adequate information regarding treatment, or without at least 1 year of clinical follow-up, were excluded. Associations between administration of chemotherapy or histologic grade and 1-year DFS were analyzed using Fisher’s exact test, and logistic regression was used to assess whether 1-year DFS were different in chemotherapy-treated patients when adjusted for histologic grade. Results: In total, 117 cases reviewed indicated an appendiceal pathology. Of these, 54 cases in a total of 51 patients met the specified criteria for pathology and completeness and length of follow-up information. The average age was 58 years (range 26-81 years). Adenocarcinoma was graded as low in 15 (28%) cases, intermediate in 18 (33%) cases, and high in 21 (39%) cases. 23 (43%) patients received no chemotherapy while 31 (57%) received chemotherapy before and/or after surgery. In the overall population, there was no significant effect of chemotherapy on survival, with 1-year DFS demonstrated in 74.2% of patients receiving some chemotherapy and 70% in patients not receiving chemotherapy (p = 0.765). One-year DFS was achieved in 86% of low-grade cases, 61% of intermediate-grade cases, and 71% of high-grade cases, though this was also not statistically significant (p = 0.254). Furthermore, when 1-year DFS between chemotherapy and non-chemotherapy patients was adjusted for grade, there was again no significant interaction (odds ratio = 0.48, 95% C.I. (0.13-1.64), p = 0.763). Conclusions: In this small, single-institution experience of patients with peritoneal appendiceal adenocarcinoma, there was no significant effect of chemotherapy administration on 1-year DFS. These findings are likely affected by significant confounding with the small sample size and retrospective nature of the data. Further investigation on a larger scale is warranted.

Preliminary clinical and biologic results of GB1275, a first-in-class oral CD11b modulator, alone and with pembrolizumab, in advanced solid tumors (KEYNOTE A36)

2505

Background: GB1275 is a first-in-class, oral CD11b modulator that reduced myeloid-derived suppressor cells (MDSCs) and tumor associated macrophages (TAMs), repolarized M2 immunosuppressive TAMs to an M1 phenotype, resulting in increased tumor infiltration of activated CD8+ T cells and antitumor efficacy in preclinical models. Here, we report preliminary results from an ongoing, first-in-human dose-escalation study in specific advanced tumors using GB1275 alone or with pembrolizumab. (NCT04060342) Methods: Phase 1 comprises dose escalation and expansion. During dose escalation, cohorts of 3 to 6 subjects were sequentially assigned to ascending dose levels of GB1275 from 100 mg to 1200 mg BID in one of two dosing regimens: Regimen A [GB1275 monotherapy orally (PO) twice a day (BID)] and Regimen B [GB1275 PO BID plus pembrolizumab 200 mg IV every 3 weeks (q3wks)]. Dose escalation was based on safety including dose-limiting toxicities (DLTs). Following dose escalation, up to 40 subjects with specific tumor types are to be treated in expansion with the selected GB1275 dose plus pembrolizumab to assess safety, pharmacokinetics, and preliminary clinical and biomarker activity. Results: As of January 8, 2021, 45 subjects were treated [44 in dose escalation: 23, Regimen A; 21, Regimen B. 1 in expansion, Regimen B], with median (range) GB1275 exposure of 42.0 days (4-263). No DLTs were reported. GB1275-related adverse events occurred in 24/45 (53.3%) subjects; photosensitivity reaction (20.0%), dysesthesia (13.3%) and pruritus (13.3%) were most frequent (≥10%). Stable disease was reported in 6/19 (31.6%) response-evaluable subjects in Regimen A and 9/16 (56.3%) in Regimen B. In Regimen B (800 mg), one partial response was reported in a subject with MSS-CRC treated for 263 days, and one prolonged stable disease (227 days) was reported in a gastric cancer (GC) subject previously treated with pembrolizumab plus bavituximab for less than 3 months due to progression; both subjects are continuing study treatment. A dose-dependent increase in GB1275 systemic exposure was observed up to 800 mg BID. Down-regulation of peripheral MDSCs was seen with both regimens. Regimen-dependent gene clusters in whole blood were noted. An increase in tumor infiltrating lymphocyte (TIL) counts was noted in both Regimens A and B. Conclusions: Dose escalation of GB1275, up to 1200 mg in Regimens A and B, demonstrated tolerability as monotherapy and combined with pembrolizumab in subjects with advanced cancers. Encouraging antitumor activity in Regimen B (800 mg) was observed in subjects with MSS-CRC and GC. Biological activity reflected by MDSC modulations in blood and TIL Increases in tumor biopsies with GB1275 alone and with pembrolizumab supports the mechanism of GB1275. GB1275 800 mg BID plus pembrolizumab 200 mg IV q3wks was selected for evaluation in the expansion phase. Clinical trial information: NCT04060342.

Innate Immune Checkpoint Inhibitors: The Next Breakthrough in Medical Oncology?

While immunotherapy has revolutionized the treatment of many types of advanced cancer, most patients still do not derive benefit. The currently available immune checkpoint inhibitors target the adaptive immune system, generating a T-cell antitumor response. However, an antitumor immune response depends on a complex interplay of both innate and adaptive immune cells. The innate immune system is a promising new target, and innate immune checkpoint inhibitors can disrupt inhibitory interactions ("don't eat me" signals) between tumor and both phagocytes and natural killer cells. The checkpoint inhibitor may also provide a stimulatory interaction ("eat me" signal), or this can be achieved through use of combination therapy. This generates antitumor effector functions including phagocytosis, natural cytotoxicity, antibody-dependent effects, and synergistic activation of the adaptive immune system via antigen presentation. This is a rapidly expanding area of drug development, either alone or in combination (with anticancer antibodies or adaptive immune checkpoint inhibitors). Here, we comprehensively review the mechanism of action and up-to-date solid tumor clinical trial data of the drugs targeting phagocytosis checkpoints (SIRPα/CD47, LILRB1/MHC-I, and LILRB2/MHC-I) and natural killer-cell checkpoints (TIGIT/CD112 + CD155, PVRIG/CD112, KIRs/MHC-I, and NKG2A-CD94/HLA-E). Innate immune checkpoint inhibitors could once again revolutionize immune-based cancer therapies.

Response to radiotherapy in pancreatic ductal adenocarcinoma is enhanced by inhibition of myeloid-derived suppressor cells using STAT3 anti-sense oligonucleotide

Pancreatic ductal adenocarcinoma (PDAC) has a heterogeneous tumor microenvironment (TME) comprised of myeloid-derived suppressor cells (MDSCs), tumor-associated macrophages, neutrophils, regulatory T cells, and myofibroblasts. The precise mechanisms that regulate the composition of the TME and how they contribute to radiotherapy (RT) response remain poorly understood. In this study, we analyze changes in immune cell populations and circulating chemokines in patient samples and animal models of pancreatic cancer to characterize the immune response to radiotherapy. Further, we identify STAT3 as a key mediator of immunosuppression post-RT. We found granulocytic MDSCs (G-MDSCs) and neutrophils to be increased in response to RT in murine and human PDAC samples. We also found that RT-induced STAT3 phosphorylation correlated with increased MDSC infiltration and proliferation. Targeting STAT3 using an anti-sense oligonucleotide in combination with RT circumvented RT-induced MDSC infiltration, enhanced the proportion of effector T cells, and improved response to RT. In addition, STAT3 inhibition contributed to the remodeling of the PDAC extracellular matrix when combined with RT, resulting in decreased collagen deposition and fibrotic tissue formation. Collectively, our data provide evidence that targeting STAT3 in combination with RT can mitigate the pro-tumorigenic effects of RT and improve tumor response.

Testing Cancer Immunotherapy in a Human Immune System Mouse Model: Correlating Treatment Responses to Human Chimerism, Therapeutic Variables and Immune Cell Phenotypes

Over the past decade, immunotherapies have revolutionized the treatment of cancer. Although the success of immunotherapy is remarkable, it is still limited to a subset of patients. More than 1500 clinical trials are currently ongoing with a goal of improving the efficacy of immunotherapy through co-administration of other agents. Preclinical, small-animal models are strongly desired to increase the pace of scientific discovery, while reducing the cost of combination drug testing in humans. Human immune system (HIS) mice are highly immune-deficient mouse recipients rtpeconstituted with human hematopoietic stem cells. These HIS-mice are capable of growing human tumor cell lines and patient-derived tumor xenografts. This model allows rapid testing of multiple, immune-related therapeutics for tumors originating from unique clinical samples. Using a cord blood-derived HIS-BALB/c-Rag2nullIl2rγnullSIRPαNOD (BRGS) mouse model, we summarize our experiments testing immune checkpoint blockade combinations in these mice bearing a variety of human tumors, including breast, colorectal, pancreatic, lung, adrenocortical, melanoma and hematological malignancies. We present in-depth characterization of the kinetics and subsets of the HIS in lymph and non-lymph organs and relate these to protocol development and immune-related treatment responses. Furthermore, we compare the phenotype of the HIS in lymph tissues and tumors. We show that the immunotype and amount of tumor infiltrating leukocytes are widely-variable and that this phenotype is tumor-dependent in the HIS-BRGS model. We further present flow cytometric analyses of immune cell subsets, activation state, cytokine production and inhibitory receptor expression in peripheral lymph organs and tumors. We show that responding tumors bear human infiltrating T cells with a more inflammatory signature compared to non-responding tumors, similar to reports of "responding" patients in human immunotherapy clinical trials. Collectively these data support the use of HIS mice as a preclinical model to test combination immunotherapies for human cancers, if careful attention is taken to both protocol details and data analysis.

WEE1 Inhibition in Combination With Targeted Agents and Standard Chemotherapy in Preclinical Models of Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal cancer with high incidences of p53 mutations. AZD1775 (adavosertib, previously MK-1775) is a small molecule WEE1 inhibitor that abrogates the G2M checkpoint and can potentially synergize with DNA damaging therapies commonly used in PDAC treatment. The purpose of this study was to identify combination partners for AZD1775, including standard chemotherapy or targeted agents, in PDAC preclinical models. Low powered preliminary screens demonstrated that two of the four PDX models responded better to the combinations of AZD1775 with irinotecan or capecitabine than to either single agent. Following the screens, two full powered PDAC PDX models of differing p53 status were tested with the combinations of AZD1775 and irinotecan or capecitabine. The combinations of AZD1775 and SN38 or 5-FU were also tested on PDAC cell lines. Cellular proliferation was measured using an IncuCyte Live Cell Imager and apoptosis was measured using a Caspase-Glo 3/7 assay. Flow cytometry was conducted to measure alterations in cell cycle distribution. Western blot analysis was used to determine the effects of the drug combinations on downstream effectors. In PDX models with mutated p53 status, there was significant tumor growth inhibition from the combination of AZD1775 with irinotecan or capecitabine (P ≤ 0.03), while PDX models with wild type p53 did not show anti-tumor synergy from the same combinations (P ≥ 0.08). The combination of AZD1775 with SN38 or 5-FU significantly decreased proliferation in all PDAC cell lines, and enhanced apoptosis in multiple cell lines. Cell cycle distribution was disrupted from the combination of AZD1775 with SN38 or 5-FU which was recorded as G2M arrest and decreased G1 phase. AZD1775 inhibited phospho-CDC2 and increased the expression of γH2AX that was either maintained or enhanced after combination with SN38 or 5-FU. The combination of AZD1775 with irinotecan/SN38 or capecitabine/5-FU showed anti-tumor effects in vivo and in vitro in PDAC models. These results support further investigation for these combination strategies to enhance outcomes for PDAC patients.

Sacituzumab govitecan, a Trop-2-directed antibody-drug conjugate, for patients with epithelial cancer: final safety and efficacy results from the phase I/II IMMU-132-01 basket trial

BACKGROUND

Sacituzumab govitecan (SG), a trophoblast cell surface antigen-2 (Trop-2)-directed antibody-drug conjugate, has demonstrated antitumor efficacy and acceptable tolerability in a phase I/II multicenter trial (NCT01631552) in patients with advanced epithelial cancers. This report summarizes the safety data from the overall safety population (OSP) and efficacy data, including additional disease cohorts not published previously.

PATIENTS AND METHODS

Patients with refractory metastatic epithelial cancers received intravenous SG (8, 10, 12, or 18 mg/kg) on days 1 and 8 of 21-day cycles until disease progression or unacceptable toxicity. Endpoints for the OSP included safety and pharmacokinetic parameters with investigator-evaluated objective response rate (ORR per RECIST 1.1), duration of response, clinical benefit rate, progression-free survival, and overall survival evaluated for cohorts (n > 10 patients) of small-cell lung, colorectal, esophageal, endometrial, pancreatic ductal adenocarcinoma, and castrate-resistant prostate cancer.

RESULTS

In the OSP (n = 495, median age 61 years, 68% female; UGT1A1∗28 homozygous, n = 46; 9.3%), 41 (8.3%) permanently discontinued treatment due to adverse events (AEs). Most common treatment-related AEs were nausea (62.6%), diarrhea (56.2%), fatigue (48.3%), alopecia (40.4%), and neutropenia (57.8%). Most common treatment-related serious AEs (n = 75; 15.2%) were febrile neutropenia (4.0%) and diarrhea (2.8%). Grade ≥3 neutropenia and febrile neutropenia occurred in 42.4% and 5.3% of patients, respectively. Neutropenia (all grades) was numerically more frequent in UGT1A1∗28 homozygotes (28/46; 60.9%) than heterozygotes (69/180; 38.3%) or UGT1A1∗1 wild type (59/177; 33.3%). There was one treatment-related death due to an AE of aspiration pneumonia. Partial responses were seen in endometrial cancer (4/18, 22.2% ORR) and small-cell lung cancer (11/62, 17.7% ORR), and one castrate-resistant prostate cancer patient had a complete response (n = 1/11; 9.1% ORR).

CONCLUSIONS

SG demonstrated a toxicity profile consistent with previous published reports. Efficacy was seen in several cancer cohorts, which validates Trop-2 as a broad target in solid tumors.

Colon Cancer, Version 2.2021, NCCN Clinical Practice Guidelines in Oncology

This selection from the NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines) for Colon Cancer focuses on systemic therapy options for the treatment of metastatic colorectal cancer (mCRC), because important updates have recently been made to this section. These updates include recommendations for first-line use of checkpoint inhibitors for mCRC, that is deficient mismatch repair/microsatellite instability-high, recommendations related to the use of biosimilars, and expanded recommendations for biomarker testing. The systemic therapy recommendations now include targeted therapy options for patients with mCRC that is HER2-amplified, or BRAF V600E mutation-positive. Treatment and management of nonmetastatic or resectable/ablatable metastatic disease are discussed in the complete version of the NCCN Guidelines for Colon Cancer available at NCCN.org. Additional topics covered in the complete version include risk assessment, staging, pathology, posttreatment surveillance, and survivorship.

Induction of ADAM10 by Radiation Therapy Drives Fibrosis, Resistance, and Epithelial-to-Mesenchyal Transition in Pancreatic Cancer

Stromal fibrosis activates prosurvival and proepithelial-to-mesenchymal transition (EMT) pathways in pancreatic ductal adenocarcinoma (PDAC). In patient tumors treated with neoadjuvant stereotactic body radiation therapy (SBRT), we found upregulation of fibrosis, extracellular matrix (ECM), and EMT gene signatures, which can drive therapeutic resistance and tumor invasion. Molecular, functional, and translational analysis identified two cell-surface proteins, a disintegrin and metalloprotease 10 (ADAM10) and ephrinB2, as drivers of fibrosis and tumor progression after radiation therapy (RT). RT resulted in increased ADAM10 expression in tumor cells, leading to cleavage of ephrinB2, which was also detected in plasma. Pharmacologic or genetic targeting of ADAM10 decreased RT-induced fibrosis and tissue tension, tumor cell migration, and invasion, sensitizing orthotopic tumors to radiation killing and prolonging mouse survival. Inhibition of ADAM10 and genetic ablation of ephrinB2 in fibroblasts reduced the metastatic potential of tumor cells after RT. Stimulation of tumor cells with ephrinB2 FC protein reversed the reduction in tumor cell invasion with ADAM10 ablation. These findings represent a model of PDAC adaptation that explains resistance and metastasis after RT and identifies a targetable pathway to enhance RT efficacy. SIGNIFICANCE: Targeting a previously unidentified adaptive resistance mechanism to radiation therapy in PDAC tumors in combination with radiation therapy could increase survival of the 40% of PDAC patients with locally advanced disease.See related commentary by Garcia Garcia et al., p. 3158 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/81/12/3255/F1.large.jpg.

A single-institution experience using total neoadjuvant therapy to treat locally advanced rectal cancer

64

Background: The management of locally advanced rectal cancer has historically included preoperative chemoradiation followed by surgery and then adjuvant chemotherapy. Recently there has been an increasing utilization of preoperative chemotherapy in addition to standard chemoradiation, a strategy known as total neoadjuvant therapy (TNT). TNT has been offered to patients at the University of Colorado Cancer Center since 2015. Methods: Records of all patients presenting to the University of Colorado colorectal multidisciplinary clinic since 2015 were screened for treatment with TNT. Data collected on these patients included demographic information, diagnosis and initial staging, preoperative treatment received, and surgical outcomes including treatment response and pathological stage. TNT included preoperative chemotherapy with oxaliplatin combined with either 5-FU (FOLFOX) or capecitabine (CAPOX) as well as chemoradiation, generally given with concurrent capecitabine. Patients then underwent surgical resection; if a complete clinical response was achieved with TNT, non-operative management (NOM) was offered. Results: A total of 81 patients thus far have undergone TNT followed by resection or, if complete clinical response and preferred by the patient, NOM. The mean age of patients was 56 years, ranging from 23 to 87, and 60% of patients were male. The majority of patients (67) had stage III disease at presentation while 1 had stage 1 (T2N0) disease, 11 had stage II disease and 2 patients had oligometastatic disease. Ultimately 13 patients (16%) opted for non-operative management after being found to have a complete clinical response following TNT. Of the 68 patients who underwent surgical resection, 21 (31%) had a pathological complete response, with another 14 (21%) with near-complete response. 28 patients (41%) had a partial treatment response and 5 (7%) had no treatment response. In total, the rate of complete clinical or pathologic response was 42%. Treatment was overall well-tolerated with 90% of patients receiving the full planned dose of radiation and 98% of patients completing all planned cycles of chemotherapy, though most of them with typical dose reductions needed. Of the patients who underwent surgery, 49 (72%) had low anterior resection and 19 (28%) had an abdominoperineal resection. Of patients with temporary ileostomies, 85% of them had their ileostomy reversed within 10 weeks of surgery. Conclusions: Treatment of locally advanced rectal cancer by a total neoadjuvant approach is well-tolerated and results in a high rate of clinical and pathological complete response.

Preclinical and Dose-Finding Phase I Trial Results of Combined Treatment with a TORC1/2 Inhibitor (TAK-228) and Aurora A Kinase Inhibitor (Alisertib) in Solid Tumors

PURPOSE

The purpose of this study was to evaluate the rational combination of TORC1/2 inhibitor TAK-228 and Aurora A kinase inhibitor alisertib in preclinical models of triple-negative breast cancer (TNBC) and to conduct a phase I dose escalation trial in patients with advanced solid tumors.

EXPERIMENTAL DESIGN

TNBC cell lines and patient-derived xenograft (PDX) models were treated with alisertib, TAK-228, or the combination and evaluated for changes in proliferation, cell cycle, mTOR pathway modulation, and terminal cellular fate, including apoptosis and senescence. A phase I clinical trial was conducted in patients with advanced solid tumors treated with escalating doses of alisertib and TAK-228 using a 3+3 design to determine the maximum tolerated dose (MTD).

RESULTS

The combination of TAK-228 and alisertib resulted in decreased proliferation and cell-cycle arrest in TNBC cell lines. Treatment of TNBC PDX models resulted in significant tumor growth inhibition and increased apoptosis with the combination. In the phase I dose escalation study, 18 patients with refractory solid tumors were enrolled. The MTD was alisertib 30 mg b.i.d. days 1 to 7 of a 21-day cycle and TAK-228 2 mg daily, continuous dosing. The most common treatment-related adverse events were neutropenia, fatigue, nausea, rash, mucositis, and alopecia.

CONCLUSIONS

The addition of TAK-228 to alisertib potentiates the antitumor activity of alisertib in vivo, resulting in increased cell death and apoptosis. The combination is tolerable in patients with advanced solid tumors and should be evaluated further in expansion cohorts with additional pharmacodynamic assessment.

High incidence of prolonged rectal bleeding and advanced stage cancer in early-onset colorectal cancer patients

Background: We examined characteristics of early-onset colorectal cancer (CRC) patients to identified factors, which may lead to earlier diagnosis. Materials & methods: This is a retrospective study with inclusion criteria: CRC diagnosed between 2012 and 2018 and age at diagnosis <50 years. Results: A total of 209 patients were included (mean age 41.8 years). Of those patients 42.5% had rectal cancer and 37.8% were stage IV at initial diagnosis. Of patients with data available for rectal bleeding history (n = 173), 50.8% presented with rectal bleeding and median time from onset of bleeding to diagnosis was 180 days (interquartile range 60–365), with longer duration noted in advanced cancer. Conclusion: Prolonged rectal bleeding history was noted in a significant proportion of early-onset CRC patients, with longer duration of rectal bleeding noted in stage IV patients. Patients and primary care physicians should be made aware of this finding in order to facilitate timely referral for diagnostic workup.

Bitter melon juice intake with gemcitabine intervention circumvents resistance to gemcitabine in pancreatic patient-derived xenograft tumors

Chemoresistance to gemcitabine (GEM)-a frontline chemotherapeutic, resulting from its dysfunctional uptake and metabolism in cancer cells, is a major contributing factor for failed therapy in pancreatic cancer (PanC) patients. Therefore, there is an urgent need for agents that could reverse GEM resistance and allow continued chemosensitivity to the drug. We employed natural nontoxic agent (with anti-PanC potential) bitter melon juice (BMJ) and GEM to examine their combinatorial benefits against tumorigenesis of PanC patient-derived xenograft (PDX)-pancreatic ductal adenocarcinomas explants PDX272 (wild-type KRAS), PDX271 (mutant KRAS and SMAD4), and PDX266 (mutant KRAS). Anti-PanC efficacy of single agents vs combination in the three tumor explants, both at the end of active dosing regimen and following a drug-washout phase were compared. In animal studies, GEM alone treatment significantly inhibited PDX tumor growth, but effects were not sustained, as GEM-treated tumors exhibited regrowth posttreatment termination. However, combination-regimen displayed enhanced and sustained efficacy. Mechanistic assessments revealed that overcoming GEM resistance by coadministration with BMJ was possibly due to modulation of GEM transport/metabolism pathway molecules (ribonucleotide reductase regulatory subunit M1, human equilibrative nucleoside transporter 1, and deoxycytidine kinase). Study outcomes, highlighting significantly higher and sustained efficacy of GEM in combination with BMJ, make a compelling case for a clinical trial in PanC patients, wherein BMJ could be combined with GEM to target and overcome GEM resistance. In addition, given their specific effectiveness against KRAS-mutant tumors, this combination could be potentially beneficial to a broader PanC patient population.

Small Bowel Adenocarcinoma, Version 1.2020, NCCN Clinical Practice Guidelines in Oncology

Small bowel adenocarcinoma (SBA) is a rare malignancy of the gastrointestinal tract that has increased in incidence across recent years. Often diagnosed at an advanced stage, outcomes for SBA are worse on average than for other related malignancies, including colorectal cancer. Due to the rarity of this disease, few studies have been done to direct optimal treatment, although recent data have shown that SBA responds to treatment differently than colorectal cancer, necessitating a separate approach to treatment. The NCCN Guidelines for Small Bowel Adenocarcinoma were created to establish an evidence-based standard of care for patients with SBA. These guidelines provide recommendations on the workup of suspected SBA, primary treatment options, adjuvant treatment, surveillance, and systemic therapy for metastatic disease. Additionally, principles of imaging and endoscopy, pathologic review, surgery, radiation therapy, and survivorship are described.

Abstract 6387: Therapeutic targeting of lipid oxidation and apoptosis in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is currently the fourth leading cause of cancer deaths with more than 56,000 new cases estimated to be diagnosed in 2019. Current treatment options for PDAC include radiation and chemotherapeutic regimens, however these targeted therapies are ineffective for patients with advanced disease progression. Additionally, the dense stromal nature of PDAC tumors create challenges to target the cancer cells resulting in incomplete cell killing and eventual drug resistance. Recent evidence has shown that CPT1A, an enzyme that regulates the entry of lipids into mitochondria for β-oxidation, is strongly expressed in several cancers. CPT1A is located on the mitochondrial membrane and potentially interacts with BCL-2, an anti-apoptotic protein that promotes tumor maintenance and metastasis. Metabolic stress can activate the anti-apoptotic effects of BCL-2, reprograming metabolism to use fat oxidation for cancer survival. Therefore, a co-inhibition using the selective BCL-2 inhibitor, venetoclax, with agents that inhibit CPT1A and β-oxidation, could be a novel strategy for PDAC. There are few studies considering CPT1A as a therapeutic target for PDAC. Current available drugs to target these pathways include the anti-anginal ranolazine, and CPT1A inhibitors etomoxir and perhexiline. Previous studies have shown that expression of BCL-2 by tumor cells is necessary for BCL-2 inhibitors to be effective. We initially wanted to determine the expression of BCL-2 and CPT1A in PDAC cells utilizing western blot and rtPCR, and to confirm their proximity using a proximity ligation assay (PLA). PDAC cells were then plated in 96 well plates and Cell Titer-Glo assays were performed to determine effective concentrations of single agent venetoclax, etomoxir, and perhexiline. The effects of these drugs in combination were then evaluated using a clonogenic assay, which was analyzed using the ImageJ colony area plugin. PDAC cells were then exposed to the combinations and western blots were performed to evaluate changes downstream effectors. We have confirmed the expression of BCL-2 and CPT1A on the mitochondrial membrane using Westerns, rtPCR, and a PLA on several PDAC lines. Though single agent drugs had little effect on cell viability, the combination of venetoclax with CPT1A and β-oxidation inhibitors decreased colony formation in some PDAC cell lines. Western blot analysis revealed the drug combinations affected the phosphorylation of AKT and 4E-BP1 and expression of the pro-apoptotic protein BID. These data suggest that co-targeting BCL-2 and CPT1A have potential for anti-tumor effects in PDAC. Additional research into the role of CPT1A in PDAC biology will elucidate the optimal dosing concentrations and mechanisms for further studies.

Citation Format: Sarah J. Hartman, Nathalie Nadales, Stacey M. Bagby, Betelehem W. Yacob, Brian L. Gittleman, Adriana Estrada-Bernal, Anh T. Le, Christopher H. Lieu, S. Lindsey Davis, Alexis D. Leal, Jennifer R. Diamond, Wells A. Messersmith, Isabel R. Schlaepfer, Todd M. Pitts. Therapeutic targeting of lipid oxidation and apoptosis in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6387.

Abstract 6647: Sensitizing microsatellite stable colorectal cancer to immune checkpoint therapy utilizing Wnt pathway inhibition

Immunotherapies that target immune regulatory checkpoints such as CTLA-4 and PD-1 are widely used among many cancer types and have shown positive results in CRC with high microsatellite instability. However, in microsatellite stable (MSS) CRC there is a dismal response rate of 0%. The limited efficacy has shown to be partially due to the lack of T-cells in the tumor microenvironment and/or no activation/regulation of paramount cells in the immune system. The Wnt pathway is the most commonly altered pathway in CRC and is highly involved in driving tumor initiation and progression. Recent evidence also demonstrates the Wnt pathway is involved in T-lymphocyte development, maturation/activation of CD8+ effector T cells and recruitment of dendritic cells. Therefore, targeting the Wnt pathway utilizing a Porcupine (PORCN) inhibitor (ETC-159) in MSS CRC may be a promising strategy to sensitize tumors to immune checkpoint inhibition.

Human Immune System BRGS (BALB/c, Rag2−/−, IL2RγC−/−, NODSIRPα) mice were engrafted with MSS CRC PDX (hPDX). The hPDX were randomized according to human chimerism into the following drug treatments groups: Vehicle, ETC-159, nivolumab, and the combination. Treatments began when tumors reached 100-300mm3 and tumors were measured twice weekly. At the end of study, sera, lymph nodes, spleen, and tumor tissue were collected for immunohistochemistry, single cell suspensions, and flow cytometry analysis.

Combination therapy resulted in a significant decrease in tumor volume compared to both single agents and vehicle. Flow cytometric analysis demonstrated an increase in human immune cells, in particular human CD4 and CD8 cells in the combination compared to the vehicle and nivolumab treated groups. Additionally, these T-cells showed increased signs of activation and effector function, as indicated by increased CD69+ expression, effector memory subsets, and granzyme B+ cells in the TILs, with a further reduction in Treg populations, suggesting an overall increase in inflammation. An increase in MHC II expression on tumor cells was observed in the ETC-159 single agent with a statistically significant increase in the combination treated tumors demonstrating enhanced antigen presentation. Furthermore, PD-1 expression was upregulated on CD4+ T-cells in the ETC-159 single agent. Lastly, VECTRA analysis corroborates the flow cytometry data showing a changing tumor immune landscape through an increase in CD4+ and CD8+ T cells in the tumor and surrounding stroma.

Our data demonstrates the combination treatment of ETC-159 + nivolumab in MSS CRC hPDX show increased tumor infiltration of human immune cells. Further preclinical data is compulsory but these results support further development of this combination in clinical trials.

Citation Format: Stacey M. Bagby, Sarah J. Hartman, Natalie M. Navarro, Betelehem W. Yacob, Jeremy Shulman, Jessica Barkow, Christopher H. Lieu, S. Lindsey Davis, Alexis D. Leal, Wells A. Messersmith, Angela Minic, Kimberly R. Jordan, Julie Lang, Todd M. Pitts. Sensitizing microsatellite stable colorectal cancer to immune checkpoint therapy utilizing Wnt pathway inhibition [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 6647.

NCCN Guidelines Updates: Management of Metastatic Colorectal Cancer

In the last year, several impactful updates have been added to the NCCN Guidelines for Colorectal Cancer (CRC) for the management of metastatic disease, including additional options for BRAF-mutated advanced CRC and the inclusion of combination immunotherapy (PD-1 and CTLA-4) for deficient mismatch repair/microsatellite instability (MSI)-high advanced CRC. According to Dr. Wells A. Messersmith, targeted therapies (ie, VEGFR, EGFR, multitargeted tyrosine kinase inhibitors) play an important role in CRC management, but none of them have been successful in the adjuvant setting (although checkpoint inhibition is now being tested in MSI-high stage III CRC). Reliable predictive biomarkers for most agents are still greatly lacking, highlighting the importance of investing in CRC biomarker studies.

NCCN Guidelines Insights: Rectal Cancer, Version 6.2020

The NCCN Guidelines for Rectal Cancer provide recommendations for the diagnosis, evaluation, treatment, and follow-up of patients with rectal cancer. These NCCN Guidelines Insights summarize the panel discussion behind recent important updates to the guidelines. These updates include clarifying the definition of rectum and differentiating the rectum from the sigmoid colon; the total neoadjuvant therapy approach for localized rectal cancer; and biomarker-targeted therapy for metastatic colorectal cancer, with a focus on new treatment options for patients with BRAF V600E- or HER2 amplification-positive disease.

First-in-Class Inhibitors of Oncogenic CHD1L with Preclinical Activity against Colorectal Cancer

Since the discovery of CHD1L in 2008, it has emerged as an oncogene implicated in the pathology and poor prognosis of a variety of cancers, including gastrointestinal cancers. However, a mechanistic understanding of CHD1L as a driver of colorectal cancer has been limited. Until now, there have been no reported inhibitors of CHD1L, also limiting its development as a molecular target. We sought to characterize the clinicopathologic link between CHD1L and colorectal cancer, determine the mechanism(s) by which CHD1L drives malignant colorectal cancer, and discover the first inhibitors with potential for novel treatments for colorectal cancer. The clinicopathologic characteristics associated with CHD1L expression were evaluated using microarray data from 585 patients with colorectal cancer. Further analysis of microarray data indicated that CHD1L may function through the Wnt/TCF pathway. Thus, we conducted knockdown and overexpression studies with CHD1L to determine its role in Wnt/TCF-driven epithelial-to-mesenchymal transition (EMT). We performed high-throughput screening (HTS) to identify the first CHD1L inhibitors. The mechanism of action, antitumor efficacy, and drug-like properties of lead CHD1L inhibitors were determined using biochemical assays, cell models, tumor organoids, patient-derived tumor organoids, and in vivo pharmacokinetics and pharmacodynamics. Lead CHD1L inhibitors display potent in vitro antitumor activity by reversing TCF-driven EMT. The best lead CHD1L inhibitor possesses drug-like properties in pharmacokinetic/pharmacodynamic mouse models. This work validates CHD1L as a druggable target and establishes a novel therapeutic strategy for the treatment of colorectal cancer.

A phase 1b dose escalation study of Wnt pathway inhibitor vantictumab in combination with nab-paclitaxel and gemcitabine in patients with previously untreated metastatic pancreatic cancer

Vantictumab is a fully human monoclonal antibody that inhibits Wnt pathway signaling through binding FZD1, 2, 5, 7, and 8 receptors. This phase Ib study evaluated vantictumab in combination with nab-paclitaxel and gemcitabine in patients with untreated metastatic pancreatic adenocarcinoma. Patients received vantictumab at escalating doses in combination with standard dosing of nab-paclitaxel and gemcitabine according to a 3 + 3 design. A total of 31 patients were treated in 5 dosing cohorts. Fragility fractures attributed to vantictumab occurred in 2 patients in Cohort 2 (7 mg/kg every 2 weeks), and this maximum administered dose (MAD) on study was considered unsafe. The dosing schedule was revised to every 4 weeks for Cohorts 3 through 5, with additional bone safety parameters added. Sequential dosing of vantictumab followed by nab-paclitaxel and gemcitabine was also explored. No fragility fractures attributed to vantictumab occurred in these cohorts; pathologic fracture not attributed to vantictumab was documented in 2 patients. The study was ultimately terminated due to concerns around bone-related safety, and thus the maximum tolerated dose (MTD) of the combination was not determined. The MAD of vantictumab according to the revised dosing schedule was 5 mg/kg (n = 16).