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Identification of circulating tumor DNA (ctDNA) following curative intent therapies is a surrogate for microscopic residual disease for patients with metastatic colorectal cancer (mCRC). Preclinically, in micrometastatic microsatellite stable (MSS) colorectal cancer, increased TGFβ signaling results in exclusion of antitumor cytotoxic T cells from the tumor microenvironment. Bintrafusp alfa (BA) is a bifunctional fusion protein composed of the extracellular domain of the TGFβRII receptor (“TGFβ trap”) and anti-PD-L1 antibody. Patients with liver-limited, MSS mCRC and with detected ctDNA after complete resection of all known tumors and standard-of-care therapy were treated with 1,200 mg of BA intravenously every 14 days for six doses. The primary endpoint was ctDNA clearance. Radiographic characteristics at recurrence were compared using independent t tests to historical data from a similar cohort of patients with liver-limited mCRC who underwent observation. Only 4 of 15 planned patients received BA before the study was stopped early for loss of equipoise. There was no grade ≥3 adverse event. None of the patients cleared ctDNA. All patients developed radiographic recurrence by the first planned restaging. Although not detectable at prior to treatment, TGFβ3 was found in circulation in all patients at cycle 2 day 1. Compared with a historical cohort, patients administered BA developed more metastases (15 vs. 2, P = 0.005) and greater tumor volumes (9 cm vs. 2 cm, P = 0.05). Treatment with BA in patients with ctDNA-detected, liver-limited mCRC did not clear ctDNA and was associated with large-volume recurrence, highlighting the potential context-specific complexity of dual TGFβ and PD-L1 inhibition. Significance: Use of ctDNA to identify patients with micrometastatic disease for therapeutic intervention is feasible. Treatment with BA in patients with liver-limited mCRC and with detectable ctDNA after resection generated rapid progression. Approaches targeting TGFβ signaling must consider its pathway complexity in future immunotherapy combination strategies.

The benefit of radiation therapy for pancreatic ductal adenocarcinoma (PDAC) remains unclear. We hypothesized that a new mechanistic mathematical model of chemotherapy and radiation response could predict clinical outcomes a priori, using a previously described baseline measurement of perfusion from computed tomography scans, normalized area under the enhancement curve (nAUC).We simplified an existing mass transport model that predicted cancer cell death by replacing previously unknown variables with averaged direct measurements from randomly selected pathologic sections of untreated PDAC. This allowed using nAUC as the sole model input to approximate tumor perfusion. We then compared the predicted cancer cell death to the actual cell death measured from corresponding resected tumors treated with neoadjuvant chemoradiation in a calibration cohort (n = 80) and prospective cohort (n = 25). After calibration, we applied the model to 2 separate cohorts for pathologic and clinical associations: targeted therapy cohort (n = 101), cetuximab/bevacizumab + radiosensitizing chemotherapy, and standard chemoradiation cohort (n = 81), radiosensitizing chemotherapy to 50.4 Gy in 28 fractions.We established the relationship between pretreatment computed v nAUC to pathologically verified blood volume fraction of the tumor (r = 0.65; P = .009) and fractional tumor cell death (r = 0.97-0.99; P.0001) in the calibration and prospective cohorts. On multivariate analyses, accounting for traditional covariates, nAUC independently associated with overall survival in all cohorts (mean hazard ratios, 0.14-0.31). Receiver operator characteristic analyses revealed discrimination of good and bad prognostic groups in the cohorts with area under the curve values of 0.64 to 0.71.This work presents a new mathematical modeling approach to predict clinical response from chemotherapy and radiation for PDAC. Our findings indicate that oxygen/drug diffusion strongly influences clinical responses and that nAUC is a potential tool to select patients with PDAC for radiation therapy.

Background Immune checkpoint blockade (ICB) has improved outcomes for patients with microsatellite instability high (MSI-H)/deficient mismatch repair (dMMR) tumors. However, not all MSI-H/dMMR patients will exhibit the same ICB efficacy. Previous studies suggest that concomitant antibiotic use while receiving ICB may result in poorer outcomes. We aimed to evaluate this association in patients with MSI-H/dMMR metastatic colorectal cancer (mCRC). Materials and Methods A single-site, retrospective review of 57 patients with MSI-H/dMMR mCRC that received ICB was completed. Data collected included patient demographics, ICB information, and antibiotic use. Antibiotic exposure was considered from 90 days prior to ICB through 6 weeks after initiation. Primary endpoint was overall response rate (ORR). Results The majority of patients received pembrolizumab (27 [47%]) or nivolumab (17 [30%]) monotherapy as their ICB agent. Of the 57 patients, 19 (33.3%) had antibiotic exposure from 90 days prior to ICB initiation through 6 weeks after initiation with most (13 [68%]) having antibiotic use in the 30 days preceding ICB initiation. Similar ORRs were seen in both groups (P-value > .99). No difference was observed in OS (P-value .29) or PFS (P-value .36) between groups. Conclusion Our data show no association of lower response rates or survival in those MSI-H/dMMR patients with mCRC who receive antibiotics around the initiation of ICB. This information needs to be confirmed in a larger prospective cohort.

Chemotherapy combined with immunotherapy has improved the treatment of certain solid tumors, but effective regimens remain elusive for pancreatic ductal adenocarcinoma (PDAC). We conducted a randomized phase 2 trial evaluating the efficacy of nivolumab (nivo; anti-PD-1) and/or sotigalimab (sotiga; CD40 agonistic antibody) with gemcitabine/nab-paclitaxel (chemotherapy) in patients with first-line metastatic PDAC (NCT03214250). In 105 patients analyzed for efficacy, the primary endpoint of 1-year overall survival (OS) was met for nivo/chemo (57.7%, P = 0.006 compared to historical 1-year OS of 35%, n = 34) but was not met for sotiga/chemo (48.1%, P = 0.062, n = 36) or sotiga/nivo/chemo (41.3%, P = 0.223, n = 35). Secondary endpoints were progression-free survival, objective response rate, disease control rate, duration of response and safety. Treatment-related adverse event rates were similar across arms. Multi-omic circulating and tumor biomarker analyses identified distinct immune signatures associated with survival for nivo/chemo and sotiga/chemo. Survival after nivo/chemo correlated with a less suppressive tumor microenvironment and higher numbers of activated, antigen-experienced circulating T cells at baseline. Survival after sotiga/chemo correlated with greater intratumoral CD4 T cell infiltration and circulating differentiated CD4 T cells and antigen-presenting cells. A patient subset benefitting from sotiga/nivo/chemo was not identified. Collectively, these analyses suggest potential treatment-specific correlates of efficacy and may enable biomarker-selected patient populations in subsequent PDAC chemoimmunotherapy trials.

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Identification of circulating tumor DNA (ctDNA) following curative intent therapies is a surrogate for microscopic residual disease for patients with metastatic colorectal cancer (mCRC). Preclinically, in micrometastatic microsatellite stable (MSS) colorectal cancer, increased TGFβ signaling results in exclusion of antitumor cytotoxic T cells from the tumor microenvironment. Bintrafusp alfa (BA) is a bifunctional fusion protein composed of the extracellular domain of the TGFβRII receptor (“TGFβ trap”) and anti-PD-L1 antibody. Patients with liver-limited, MSS mCRC and with detected ctDNA after complete resection of all known tumors and standard-of-care therapy were treated with 1,200 mg of BA intravenously every 14 days for six doses. The primary endpoint was ctDNA clearance. Radiographic characteristics at recurrence were compared using independent t tests to historical data from a similar cohort of patients with liver-limited mCRC who underwent observation. Only 4 of 15 planned patients received BA before the study was stopped early for loss of equipoise. There was no grade ≥3 adverse event. None of the patients cleared ctDNA. All patients developed radiographic recurrence by the first planned restaging. Although not detectable at prior to treatment, TGFβ3 was found in circulation in all patients at cycle 2 day 1. Compared with a historical cohort, patients administered BA developed more metastases (15 vs. 2, P = 0.005) and greater tumor volumes (9 cm vs. 2 cm, P = 0.05). Treatment with BA in patients with ctDNA-detected, liver-limited mCRC did not clear ctDNA and was associated with large-volume recurrence, highlighting the potential context-specific complexity of dual TGFβ and PD-L1 inhibition.Significance:Use of ctDNA to identify patients with micrometastatic disease for therapeutic intervention is feasible. Treatment with BA in patients with liver-limited mCRC and with detectable ctDNA after resection generated rapid progression. Approaches targeting TGFβ signaling must consider its pathway complexity in future immunotherapy combination strategies.

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PDF file - 66K, Target-matched therapy in patients with pik3ca mutations (n=17).

Target-matched treatment with PI3K/AKT/mTOR pathway inhibitors in patients with diverse advanced cancers with PIK3CA mutations have shown promise. Tumors from patients with colorectal cancer were analyzed for PIK3CA, KRAS, and BRAF mutations. PIK3CA-mutated tumors were treated, whenever feasible, with agents targeting the PI3K/AKT/mTOR pathway. Of 194 patients analyzed, 31 (16%) had PIK3CA mutations and 189 (97%) were assessed for KRAS mutations. Patients with PIK3CA mutations had a higher prevalence of simultaneous KRAS mutations than patients with wild-type PIK3CA (71%, 22/31 vs. 43%, 68/158; P = 0.006). Of 31 patients with PIK3CA mutations, 17 (55%) were treated with protocols containing PI3K/AKT/mTOR pathway inhibitors [median age, 57 years; median number of prior therapies, 4; mTORC1 inhibitors (11), phosphoinositide 3-kinase (PI3K) inhibitors (5), or an AKT inhibitor (1)]. None (0/17) had a partial or complete response (PR/CR) and only 1 [6%, 95% confidence interval (CI), 0.01–0.27] had stable disease 6 months or more, which was not significantly different from a stable disease ≥6 month/PR/CR rate of 16% (11/67; 95% CI, 0.09–0.27) in patients with colorectal cancer without PIK3CA mutations treated with PI3K/AKT/mTOR pathway inhibitors (P = 0.44). Median progression-free survival was 1.9 months (95% CI, 1.5–2.3). In conclusion, our data provide preliminary evidence that in heavily pretreated patients with PIK3CA-mutant advanced colorectal cancer, protocols incorporating PI3K/AKT/mTOR inhibitors have minimal activity. PIK3CA mutations are associated with simultaneous KRAS mutations, possibly accounting for therapeutic resistance. Mol Cancer Ther; 12(12); 2857–63. ©2013 AACR.

Purpose: Aberrant activation of the intracellular tyrosine kinase Src has been implicated as a mechanism of acquired chemotherapy resistance in metastatic colorectal cancer (mCRC). Here, the oral tyrosine kinase Src inhibitor, dasatinib, was investigated in combination with FOLFOX and cetuximab.Experimental Design: We performed a phase IB/II study of 77 patients with previously treated mCRC. Primary objectives were to determine the maximum tolerated dose, dose-limiting toxicities (DLT), pharmacodynamics, and efficacy. Using a 3 + 3 design, patients received FOLFOX6 with cetuximab and escalating doses of dasatinib (100, 150, 200 mg daily), followed by a 12-patient expansion cohort at 150 mg. Phase II studies evaluated FOLFOX plus dasatinib 100 mg in KRAS c12/13mut patients or in combination with cetuximab if KRAS c12/13WT. FAK and paxillin were utilized as surrogate blood biomarkers of Src inhibition, and paired biopsies of liver metastases were obtained in patients in the expansion cohort.Results: In phase IB, the DLTs were grade 3/4 fatigue (20%) and neutropenia (23%). In phase II, grade 3/4 fatigue (23%) and pleural effusions (11%) were present. Response rates were 20% (6 of 30) in the phase IB escalation and expansion cohort and 13% (3 of 24) and 0% (0 of 23) in the KRAS c12/13WT and mutant cohorts of phase II, respectively. Median progression-free survival was 4.6, 2.3, and 2.3 months, respectively. There was no evidence of Src inhibition based on surrogate blood biomarkers or paired tumor biopsies.Conclusions: The combination of dasatinib plus FOLFOX with or without cetuximab showed only modest clinical activity in refractory colorectal cancer. This appears to be primarily due to a failure to fully inhibit Src at the achievable doses of dasatinib. The combination of dasatinib plus FOLFOX with or without cetuximab did not show meaningful clinical activity in refractory colorectal cancer due to failure to fully inhibit Src. Clin Cancer Res; 23(15); 4146–54. ©2017 AACR.

Purpose:Molecular profiling has been used to select patients for targeted therapy and determine prognosis. Noninvasive strategies are critical to hepatocellular carcinoma (HCC) given the challenge of obtaining liver tissue biopsies.Experimental Design:We analyzed blood samples from 206 patients with HCC using comprehensive genomic testing (Guardant Health) of circulating tumor DNA (ctDNA).Results:A total of 153/206 (74.3%) were men; median age, 62 years (range, 18–91 years). A total of 181/206 patients had ≥1 alteration. The total number of alterations was 680 (nonunique); median number of alterations/patient was three (range, 1–13); median mutant allele frequency (% cfDNA), 0.49% (range, 0.06%–55.03%). TP53 was the common altered gene [>120 alterations (non-unique)] followed by EGFR, MET, ARID1A, MYC, NF1, BRAF, and ERBB2 [20–38 alterations (nonunique)/gene]. Of the patients with alterations, 56.9% (103/181) had ≥1 actionable alterations, most commonly in MYC, EGFR, ERBB2, BRAF, CCNE1, MET, PIK3CA, ARID1A, CDK6, and KRAS. In these genes, amplifications occurred more frequently than mutations. Hepatitis B (HBV)-positive patients were more likely to have ERBB2 alterations, 35.7% (5/14) versus 8.8% HBV-negative (P = 0.04).Conclusions:This study represents the first large-scale analysis of blood-derived ctDNA in HCC in United States. The genomic distinction based on HCC risk factors and the high percentage of potentially actionable genomic alterations suggests potential clinical utility for this technology.

Mathematical model simulation of low delta tumor growth (lambda = 0.2)

Purpose:Pancreatic ductal adenocarcinoma (PDAC) is a heterogeneous disease with variable presentations and natural histories of disease. We hypothesized that different morphologic characteristics of PDAC tumors on diagnostic computed tomography (CT) scans would reflect their underlying biology.Experimental Design:We developed a quantitative method to categorize the PDAC morphology on pretherapy CT scans from multiple datasets of patients with resectable and metastatic disease and correlated these patterns with clinical/pathologic measurements. We modeled macroscopic lesion growth computationally to test the effects of stroma on morphologic patterns, hypothesizing that the balance of proliferation and local migration rates of the cancer cells would determine tumor morphology.Results:In localized and metastatic PDAC, quantifying the change in enhancement on CT scans at the interface between tumor and parenchyma (delta) demonstrated that patients with conspicuous (high-delta) tumors had significantly less stroma, higher likelihood of multiple common pathway mutations, more mesenchymal features, higher likelihood of early distant metastasis, and shorter survival times compared with those with inconspicuous (low-delta) tumors. Pathologic measurements of stromal and mesenchymal features of the tumors supported the mathematical model's underlying theory for PDAC growth.Conclusions:At baseline diagnosis, a visually striking and quantifiable CT imaging feature reflects the molecular and pathological heterogeneity of PDAC, and may be used to stratify patients into distinct subtypes. Moreover, growth patterns of PDAC may be described using physical principles, enabling new insights into diagnosis and treatment of this deadly disease.

Supplementary Figure from Phase II Study of Ramucirumab in Advanced Biliary Tract Cancer Previously Treated By Gemcitabine-Based Chemotherapy

Validation of peripheral blood mononuclear cells as a biomarker of Src inhibition. Freshly collected peripheral blood mononuclear cells from a healthy volunteer were treated ex-vivo with dasatinib 300 nM or hydrogen peroxide 0.05 mM. The peripheral blood mononuclear cell lysates were generated and immunoblotted for phosphoFAK [Y861] and phophopaxillin [Y118].

Univariate logistic regression models for deleterious mutation among 133 sequenced subjects (n = 26 with deleterious mutation).

Operating characteristics. A summary of the probability of stopping the trial early for the indicated true response rates.

Supplementary Figure 2

Purpose: We sought to determine whether phosphoinositide 3-kinase (PI3K) pathway mutation or activation state and rapamycin-induced feedback loop activation of Akt is associated with rapamycin sensitivity or resistance.Experimental Design: Cancer cell lines were tested for rapamycin sensitivity, Akt phosphorylation, and mTOR target inhibition. Mice injected with breast or neuroendocrine cancer cells and patients with neuroendocrine tumor (NET) were treated with rapalogs and Akt phosphorylation was assessed.Results: Thirty-one cell lines were rapamycin sensitive (RS) and 12 were relatively rapamycin resistant (RR; IC50 > 100 nmol/L). Cells with PIK3CA and/or PTEN mutations were more likely to be RS (P = 0.0123). Akt phosphorylation (S473 and T308) was significantly higher in RS cells (P < 0.0001). Rapamycin led to a significantly greater pathway inhibition and greater increase in p-Akt T308 (P < 0.0001) and p-Akt S473 (P = 0.0009) in RS cells. Rapamycin and everolimus significantly increased Akt phosphorylation but inhibited growth in an in vivo NET model (BON). In patients with NETs treated with everolimus and octreotide, progression-free survival correlated with p-Akt T308 in pretreatment (R = 0.4762, P = 0.0533) and on-treatment tumor biopsies (R = 0.6041, P = 0.0102). Patients who had a documented partial response were more likely to have an increase in p-Akt T308 with treatment compared with nonresponders (P = 0.0146).Conclusion: PIK3CA/PTEN genomic aberrations and high p-Akt levels are associated with rapamycin sensitivity in vitro. Rapamycin-mediated Akt activation is greater in RS cells, with a similar observation in patients with clinical responses on exploratory biomarker analysis; thus feedback loop activation of Akt is not a marker of resistance but rather may function as an indicator of rapamycin activity. Clin Cancer Res; 18(6); 1777–89. ©2012 AACR.

Supplemental material

Univariate Cox proportional hazards model for overall survival among all 233 patients (n deaths=211).

Lack of correlation between Src activity in PBMCs and hepatic tumors. For the patients in the expansion cohort, the change in the expression of pSrc and total Src was not correlated with a change in the phosphorlyation of the Src substrate paxillin. Patients with no change or a decrease in the expression of pSrc or Src from baseline to C2D8 were included in the "no increase" category.

Chemotherapy Response Rate by Mutation Status of Sequenced Cohort (n = 133)

Patient characteristics with statistical comparison between sequenced and unsequenced cohorts among 233 patients.

Additional methods

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Variants of Unknown Significance Identified in Study Cohort

Multivariable logistic regression model for deleterious mutation among 133 sequenced subjects (n = 26 with deleterious mutation).

Purpose: Research biopsies are frequently incorporated within clinical trials in oncology and are often a mandatory requirement for trial enrollment. However, limited information is available regarding the extent and completeness of research biopsy reporting.Experimental Design: We identified a cohort of therapeutic clinical trials where research biopsies were performed between January 2005 and October 2010 from an IR database at our institution. Clinical trial protocols were compared with the highest level of corresponding publication as a manuscript or registry report.Results: A total of 866 research biopsies were performed across 46 clinical trials, with a median of 8 patients biopsied/trial and 19 biopsies collected/trial. After a median follow-up time of 4.3 years from trial completion, 36 of 46 trials (78%) reported trial results: published manuscripts (n = 35), or registry report (n = 1). A total of 635 conducted biopsies were reported in 18 of the 46 trials (39%). Six (33%) of these 18 trials underreported the number of biopsies performed. Of 33 trials with mandatory research biopsies, 13 (39%) trials reported on these biopsies. Biopsy complications occurred in 8 trials [n = 39 patients, 6 grade 3/4 adverse events (AE)] but only 1 trial reported these. Factors associated with biopsy reporting included a larger number of biopsies (P ≤ 0.001) and serial biopsies (P < 0.001). Twelve of 16 (75%) trials with >12 biopsies performed reported on these biopsies compared with only 20% (6/30) that performed ≤12 biopsies.Conclusions: Despite ethical obligations to report research biopsies, the majority (61%) of trials do not report results from research biopsies. Complications are rarely reported in these studies. Improved reporting of results and AEs from research biopsies is needed. Clin Cancer Res; 23(21); 6450–7. ©2017 AACR.

Characteristics and Reporting by Trial

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Purpose:VEGF receptor-2 (VEGFR-2)–mediated angiogenesis contributes to pathogenesis of biliary tract cancers (BTC). We investigated ramucirumab, a mAb targeting VEGFR-2 for treatment of advanced, chemorefractory BTC.Patients and Methods:This is a phase II, single-arm trial for advanced, unresectable, pre-treated patients with BTC with ECOG 0/1, adequate liver, renal, and marrow functions. Ramucirumab was administered at 8 mg/kg, 2 weekly with restaging performed 8 weekly. Primary endpoint was progression-free survival (PFS). Secondary endpoints were overall response rate (ORR), disease control rate (DCR), overall survival (OS), and toxicity. Exploratory endpoints included correlation of tumor mutational status with PFS and OS.Results:61 patients were enrolled: the median age was 58.5 years; 59 with stage IV disease; 62%, intrahepatic cholangiocarcinoma; 22%, gallbladder cancer; and 16%, extrahepatic cholangiocarcinoma. All received prior chemotherapy: 52% had 1 prior, and rest ≥2 prior lines. Median treatment duration was 10.1 weeks (range, 2.1–86). Median PFS was 3.2 months [95% confidence interval (CI), 2.1–4.8]; median OS, 9.5 months (95% CI, 5.8–13.6). One (1.7%) patient achieved partial response; 26 (43.3%), stable disease; and 25 (41.7%), disease progression; DCR, 45%. Median 6-month PFS and OS rates were 32% (95% CI, 0.22–0.46) and 58% (95% CI, 0.47–0.72). The majority of toxicities were grade 1 or 2; grade 3 proteinuria (1, 2%), hypertension (13, 22%), and pulmonary embolism (1, 2%), and grade 4 gastrointestinal bleeding (1, 2%) occurred.Conclusions:Ramucirumab was well tolerated and resulted in PFS similar to that achieved with other chemotherapy regimens used historically for chemorefractory BTC.

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Factors Correlating with Research Biopsy Reporting from Published Manuscripts

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Univariate Cox proportional hazards model for overall survival among 133 patients (n deaths = 130).

Prespecified dose modifications for adverse events related to study drug in Phase IB and Phase II.

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