Exploiting pancreatic cancer metabolism: challenges and opportunities

Pancreatic ductal adenocarcinoma (PDAC) is a highly aggressive form of pancreatic cancer, known for its challenging diagnosis and limited treatment options. The focus on metabolic reprogramming as a key factor in tumor initiation, progression, and therapy resistance has gained prominence. In this review we focus on the impact of metabolic changes on the interplay among stromal, immune, and tumor cells, as glutamine and branched-chain amino acids (BCAAs) emerge as pivotal players in modulating immune cell functions and tumor growth. We also discuss ongoing clinical trials that explore metabolic modulation for PDAC, targeting mitochondrial metabolism, asparagine and glutamine addiction, and autophagy inhibition. Overcoming challenges in understanding nutrient effects on immune-stromal-tumor interactions holds promise for innovative therapeutic strategies.

A multicenter phase Ia study of AbGn-107, a novel antibody-drug conjugate, in patients with advanced gastrointestinal cancer

AbGn-107 is an antibody-drug conjugate directed against AG-7 antigen, a Lewis A-like glycol-epitope expressed in a variety of gastrointestinal (GI) malignancies. Based on promising antitumor activity of AbGn-107 in both in vitro and in vivo preclinical studies, we performed a GI cancer-specific Phase I trial. Standard 3 + 3 dose escalation was used evaluating intravenous doses ranging from 0.1 mg/kg every 4 weeks to 1.0 mg/kg every 2 weeks. Key eligibility included chemo-refractory locally advanced, recurrent, or metastatic gastric, colorectal, pancreatic, or biliary cancer, with ECOG PS 0-1; positive AG-7 expression was not required during dose escalation phase. Patients were treated until disease progression or unacceptable toxicity, with tumor assessments every 8 weeks. Primary objectives included safety and determination of maximum tolerated dose; secondary objectives included efficacy defined by objective response rate. Thirty-nine patients were enrolled across seven dose levels during dose escalation phase. Based on safety profile and pharmacokinetic data, 1.0 mg/kg Q2W was selected as the dose schedule for cohort expansion phase, in which an additional seven patients were enrolled. Median number of lines of prior therapy was 3 (range 1-7). AbGn-107 was generally well-tolerated, with infections, cytopenias, hyponatremia, fatigue, abdominal pain, and diarrhea representing the most common grade 3 or higher treatment-emergent adverse events. One subject achieved a partial response, while 18 (46.2%) achieved a best response of stable disease. Disease control lasting > 6 months was observed in 6 subjects (13.0%), including 4 of 15 (26.7%) treated at the highest dose level. AbGn-107 showed a reasonable safety profile and modest clinical activity in this highly pretreated patient population. Further evaluation is required to assess the clinical validity of AG-7 as a suitable antigen for therapeutic targeting. Clinical Trial information: NCT02908451.

A Large-Scale Proteomics Resource of Circulating Extracellular Vesicles for Biomarker Discovery in Pancreatic Cancer

Pancreatic cancer has the worst prognosis of all common tumors. Earlier cancer diagnosis could increase survival rates and better assessment of metastatic disease could improve patient care. As such, there is an urgent need to develop biomarkers to diagnose this deadly malignancy earlier. Analyzing circulating extracellular vesicles (cEVs) using 'liquid biopsies' offers an attractive approach to diagnose and monitor disease status. However, it is important to differentiate EV-associated proteins enriched in patients with pancreatic ductal adenocarcinoma (PDAC) from those with benign pancreatic diseases such as chronic pancreatitis and intraductal papillary mucinous neoplasm (IPMN). To meet this need, we combined the novel EVtrap method for highly efficient isolation of EVs from plasma and conducted proteomics analysis of samples from 124 individuals, including patients with PDAC, benign pancreatic diseases and controls. On average, 912 EV proteins were identified per 100μL of plasma. EVs containing high levels of PDCD6IP, SERPINA12 and RUVBL2 were associated with PDAC compared to the benign diseases in both discovery and validation cohorts. EVs with PSMB4, RUVBL2 and ANKAR were associated with metastasis, and those with CRP, RALB and CD55 correlated with poor clinical prognosis. Finally, we validated a 7-EV protein PDAC signature against a background of benign pancreatic diseases that yielded an 89% prediction accuracy for the diagnosis of PDAC. To our knowledge, our study represents the largest proteomics profiling of circulating EVs ever conducted in pancreatic cancer and provides a valuable open-source atlas to the scientific community with a comprehensive catalogue of novel cEVs that may assist in the development of biomarkers and improve the outcomes of patients with PDAC.

Results from a phase 1a/1b study of botensilimab (BOT), a novel innate/adaptive immune activator, plus balstilimab (BAL; anti-PD-1 antibody) in metastatic heavily pretreated microsatellite stable colorectal cancer (MSS CRC)

LBA8

Background: BOT promotes optimized T cell priming, activation and memory formation by strengthening antigen presenting cell/T cell co-engagement. As an Fc-enhanced next-generation anti–CTLA-4 antibody, BOT also promotes intratumoral regulatory T cell depletion and reduces complement fixation. We present results from patients with MSS CRC treated with BOT + BAL in an expanded phase 1a/1b study; NCT03860272. Methods: Patients (pts) with metastatic MSS CRC received BOT 1 or 2 mg/kg every 6 weeks (Q6W) + BAL 3 mg/kg every 2 weeks. Crossover from monotherapy to combination therapy was permitted (rescue) as well as fixed-dosing (150 mg BOT Q6W + 450 mg BAL every 3 weeks). Results: Fifty-nine combination pts were evaluable for efficacy/safety (treated as of 19 May 2022 with ≥1 Q6W imaging assessment), including one rescue and one fixed-dose pt. Median pt age was 57 (range, 25-83), 58% were female, and 76% received at least three prior lines of therapy including prior immunotherapy (34%). Median follow-up was 6.4 months (range, 1.6-29.5). In all pts, objective response rate (ORR) was 22% (95% CI, 12-35), disease control rate (DCR) was 73% (95% CI, 60-84), and median duration of response (DOR) was not reached (NR), with 9/13 responses ongoing. The 12-month overall survival (OS) rate was 61% (95% CI, 42-75), with median OS NR. Of the 13 responders, 9 had RAS mutations (7 KRAS, 2 NRAS), 0 had BRAF mutations, 0/10 had a TMB of ≥10 mutations/Mb, and 1/7 was PD-L1 positive (≥1% combined positive score). A subgroup analysis was conducted by the dose of BOT received . In 1 mg/kg pts (n=8), ORR was 38% (3/8; 95% CI, 9-76) and DCR was 100% (8/8; 95% CI, 63-100); in 2 mg/kg pts (n=50), ORR was 20% (10/50; 95% CI, 10-34) and DCR was 70% (35/50; 95% CI, 55-82). All grade treatment-related adverse events (TRAEs) occurred in 88% of pts, including grade 3 in 32%, and grade 4 in 2% of pts. Diarrhea/colitis was the only grade 3/4 TRAE occurring in more than three pts (15% grade 3, 2% grade 4). The most common grade 3 TRAEs outside of diarrhea/colitis were fatigue (5%) and pyrexia (5%). There were no grade 5 TRAEs reported. Fifteen percent of pts had a TRAE leading to discontinuation of BOT alone and 12% had a TRAE leading to discontinuation of both BOT + BAL. Conclusions: In heavily pretreated metastatic MSS CRC pts, BOT + BAL continues to demonstrate promising clinical activity with durable responses and was well tolerated with no new immune-mediated safety signals. A larger pt set, analyses by subgroup, and additional translational data will be presented at the meeting. A randomized phase 2 trial in MSS CRC pts is enrolling (NCT05608044). Clinical trial information: NCT03860272 .

Facts and Hopes in Immunotherapy of Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDAC) remains one of the most challenging cancers to treat. For patients with advanced and metastatic disease, chemotherapy has yielded only modest incremental benefits, which are not durable. Immunotherapy has revolutionized the treatment of other solid tumors by leading to cures where none existed only a decade ago, yet it has made few inroads with PDAC. A host of trials with promising preclinical data have failed, except for in a small minority of patients with selected biomarkers. There is, however, a glimmer of hope, which we seek to cultivate. In this review, we discuss recent advances in the understanding of the uniquely immunosuppressive tumor microenvironment (TME) in PDAC, learnings from completed trials of checkpoint inhibitors, TME modifiers, cellular and vaccine therapies, oncolytic viruses, and other novel approaches. We go on to discuss our expectations for improved preclinical models of immunotherapy in PDAC, new approaches to modifying the TME including the myeloid compartment, and emerging biomarkers to better select patients who may benefit from immunotherapy. We also discuss improvements in clinical trial design specific to immunotherapy that will help us better measure success when we find it. Finally, we discuss the urgent imperative to better design and execute bold, but rational, combination trials of novel agents designed to cure patients with PDAC.

Priming of Sorafenib Prior to Radiofrequency Ablation Does Not Increase Treatment Effect in Hepatocellular Carcinoma

BACKGROUND

Preclinical studies have shown that modulation of the tumor microvasculature with anti-angiogenic agents decreases tumor perfusion and may increase the efficacy of radiofrequency ablation (RFA) in hepatocellular carcinoma (HCC). Retrospective studies suggest that sorafenib given prior to RFA promotes an increase in the ablation zone, but prospective randomized data are lacking.

AIMS

We conducted a randomized, double-blind, placebo-controlled phase II trial to evaluate the efficacy of a short-course of sorafenib prior to RFA for HCC tumors sized 3.5-7 cm (NCT00813293).

METHODS

Treatment consisted of sorafenib 400 mg twice daily for 10 days or matching placebo, followed by RFA on day 10. The primary objectives were to assess if priming with sorafenib increased the volume and diameter of the RFA coagulation zone and to evaluate its impact on RFA thermal parameters. Secondary objectives included feasibility, safety and to explore the relationship between tumor blood flow on MRI and RFA effectiveness.

RESULTS

Twenty patients were randomized 1:1. Priming with sorafenib did not increase the size of ablation zone achieved with RFA and did not promote significant changes in thermal parameters, although it significantly decreased blood perfusion to the tumor by 27.9% (p = 0.01) as analyzed by DCE-MRI. No subject discontinued treatment owing to adverse events and no grade 4 toxicity was observed.

CONCLUSION

Priming of sorafenib did not enhance the effect of RFA in intermediate sized HCC. Future studies should investigate whether longer duration of treatment or a different antiangiogenic strategy in the post-procedure setting would be more effective in impairing tumor perfusion and increasing RFA efficacy.

A quantitative analysis of escalating antineoplastic medication price increases

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Background: Established antineoplastic medication prices are overall increasing, yet the yearly trend and additive cost of such increases relative to overall antineoplastic spending is often unclear. Methods: We accessed the yearly reimbursement files from Medicare Part B for parenteral antineoplastic agents (codes J8501-J9999) for the years 2010-2020 and adjusted all values to 2020 USD to account for inflation. We calculated an initial inflation-adjusted price-per-claim for every medication at the time of medication entry to the database and compared that price with the yearly price-per-claim that Medicare reimbursed. For medications whose price had increased beyond the initial inflation-adjusted price, we multiplied the annual differences with the total annual claims of the medication reimbursed in order to calculate the additional cost accrued by Medicare for every affected year. We only included medications with total annual cost >10 million USD/yr in our analysis. Results: Price increases were noted in 70.9% of already established medications annually (median 74.5%, range 52.17-81.48%). This led to an average additional extra cost of 311 million USD (range 156-492 million USD) annually, for a total of 3.1 billion USD over the 10 years of observation. This extra cost represented 4.6-9.3% of the total Medicare Part B spending for antineoplastic medications annually and this percentage rose yearly by a statistically significant 0.43% (95% CI 0.14%-0.73%, P = 0.01; R2 0.59) in absolute terms (Table). Rituximab (1,003 million USD), trastuzumab (421 million USD), and bevacizumab (326 million USD) accumulated the highest extra costs. Conclusions: The majority of established parenteral antineoplastics are affected by escalating price increases beyond the rate of inflation. Year-by-year, these increases occupy a progressively larger part of overall Medicare Part B spending. Since Medicare does not negotiate medication price nor receives rebates but rather relies on average market prices, these increases likely affect other U.S. markets as well.[Table: see text]

Large scale proteomics of circulating extracellular vesicles to reveal novel biomarkers for pancreatic cancer

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Background: Robust biomarkers are urgently needed to assist in diagnosing pancreatic cancer. Earlier cancer diagnosis could increase survival rates by an estimated 5-fold and more reliable and real-time assessment of treatment effects in patients with cancer could improve quality of life and reduce healthcare costs. Isolation of circulating extracellular vesicles (cEVs) as ‘liquid biopsies’ offers an advantageous approach to diagnose and monitor disease status. Methods: We conducted a comprehensive proteomics study of cEVs from plasma samples to identify EV proteins that may be used as biomarkers for the diagnosis and prognosis of pancreatic cancer. Patients with pancreatic ductal adenocarcinoma (PDAC) of various tumor stages, chronic pancreatitis, intraductal papillary mucinous neoplasm (IPMN), and age-matched controls were enrolled. EVs were isolated directly from plasma samples using the affinity-based EVTrap method then subject to quantitation by liquid chromatography-tandem mass spectrometry. Results: A total of 124 patients (93 with PDAC, 12 with chronic pancreatitis, 8 with IPMN and 11 controls) were included in the discovery cohort. The isolation of EVs with EVtrap allowed the identification on average of 912 EV proteins per 100µL of sample. Principal component analysis of the cEV proteome showed clear separation between PDAC and benign pancreatic diseases. Individuals with IPMN were more closely related to controls, whereas chronic pancreatitis cases were more related to PDAC. At the functional level, we noted that cytokeratin, protein folding chaperons, and actin dynamics regulators were among protein clusters more highly altered in the cEV of patients with PDAC. We further identified new cEV markers associated with metastatic disease, such as PSMB4, RUVBL2, and ANKAR, as well as other EV proteins with strong correlation to prognosis, such as CRP, RALB, and CD55. Finally, we validated a 7-protein PDACEV signature in a validation cohort of 36 separate patients (24 with PDAC, 6 with chronic pancreatitis and 6 with IPMN) which yielded an 89% prediction accuracy for the diagnosis of PDAC. Conclusions: This study provides a valuable resource to the scientific community with a comprehensive catalog of novel proteins on circulating EVs that may assist in the development of novel biomarkers and improve the outcomes of patients with pancreatic cancer.

Organoid Sensitivity Correlates with Therapeutic Response in Patients with Pancreatic Cancer

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) remains a significant health issue. For most patients there are no options for targeted therapy and existing treatments are limited by toxicity. The HOPE trial (Harnessing Organoids for PErsonalized Therapy) was a pilot feasibility trial aiming to prospectively generate patient derived organoids (PDOs) from patients with PDAC and test their drug sensitivity and correlation with clinical outcomes.

EXPERIMENTAL DESIGN

PDOs were established from a heterogeneous population of patients with PDAC including both basal and classical PDAC subtypes.

RESULTS

A method for classifying PDOs as sensitive or resistant to chemotherapy regimens was developed to predict the clinical outcome of study subjects. Drug sensitivity testing on PDOs correlated with clinical responses to treatment in individual patients.

CONCLUSION

These data support the investigation of PDOs to guide treatment in prospective interventional trials in PDAC.

CTIM-18. LUMINOS-101: INITIAL SAFETY AND TOLERABILITY OF PVSRIPO AND PEMBROLIZUMAB COMBINATION THERAPY IN RECURRENT GLIOBLASTOMA

BACKGROUND

Recurrent glioblastoma (rGBM) is rapidly fatal with current therapies. PVSRIPO is an intratumoral immunotherapy targeting CD155 on antigen-presenting and malignant cells of solid tumors. Preclinically, PVSRIPO treatment leads to systemic, tumor antigen-specific, polyfunctional T-cell–mediated anti-tumor response, predominately driven by type I/III interferons. This inflammatory signature generates anti-tumor immunity and upregulates the programmed death (PD)-1 immune checkpoint in the tumor microenvironment. Preclinical models (including GBM) have shown that PVSRIPO+anti-PD-1/L1 therapy was more efficacious than either agent alone, warranting further investigation.

METHODS

Adults with histologically confirmed rGBM (1-2 prior progressions), Karnofsky performance status (KPS) ≥70, and an active, supratentorial, contrast-enhancing lesion (1-5.5 cm), received PVSRIPO (5x107 TCID50) intratumorally via convection-enhanced delivery (Day 1), followed by 200 mg pembrolizumab IV at week 2, given every 3 weeks for up to 24 months, to evaluate the safety/efficacy of the combination. A safety lead-in period (n=3-6) with a minimum 21–28-day delay before treatment of subsequent patients was planned, with a data safety monitoring board (DSMB) evaluating safety/tolerability prior to expansion (up to N=30).

RESULTS

The first 3 patients enrolled (ages 55-60, KPS 90-100) all received PVSRIPO followed by pembrolizumab (1-5 cycles), as planned. At cutoff (26-106 days of follow-up), there were no dose-limiting toxicities, treatment-emergent (TE) serious adverse events (SAE), or TEAEs necessitating a delay in initial/subsequent pembrolizumab treatments. All patients experienced a related TEAE, all grade 1 or 2 in severity. One patient experienced an AE of special interest (peritumoral edema, resulting in headache and hemiparesis), successfully managed with low-dose bevacizumab and corticosteroids. The DSMB unanimously recommended the study proceed without modification.

CONCLUSIONS

Intratumoral PVSRIPO+pembrolizumab was reasonably well tolerated, warranting continued investigation of the safety and efficacy of this combination in patients with rGBM.

CTIM-06. CLINICAL EFFICACY AND BIOMARKER ASSESSMENT OF VT1021, A CD36/CD47 DUAL-TARGETING AGENT, IN RECURRENT GLIOBLASTOMA

Glioblastoma (GBM) is the most common and aggressive primary brain malignancy in adults and recurs after treatment in >90% of all patients. Prognosis of patients with recurrent GBM (rGBM) is poor with a median progression free survival of ~1.8 months and median overall survival of 8-10 months. VT1021, a cyclic peptide derived from prosaposin, induces the expression of thrombospondin-1 (TSP-1) in myeloid derived suppressor cells (MDSCs), which are heavily recruited to the tumor microenvironment. Following completion of the Phase 1 Dose Escalation study and determination of the RP2D, an expansion study was conducted in a heavily pretreated rGBM population. The results of the expansion study reveal that VT1021 is safe and well tolerated in rGBM. Pharmacodynamic response to VT1021 was observed by induction of TSP-1 in circulating MDSCs and in the tumor microenvironment. VT1021 demonstrated significant single agent activity. Among 22 evaluable GBM subjects, 3 had complete response (CR), 1 had partial response (PR), and 7 had stable disease (SD) with an average study duration of over 120 days. The overall disease control rate (DCR) was 50%. Among the 3 CR, 2 showed complete radiological regression of the target lesion, the third was found to have no evidence of disease upon pathological examination following surgery. Nine of the 19 (47%) evaluable subjects with available biopsy samples showed high expression levels of both CD36 AND CD47. Among these 9 subjects, 3 achieved CR, representing an overall response rate of 33.3%, with another 3 patients achieving SD for a DCR of 67%. In conclusion, VT1021 demonstrates promising single-agent clinical activity in rGBM, particularly in subjects with high expression levels of CD36 and CD47. Additional clinical studies have been planned to further investigate the efficacy of VT1021 in rGBM and other solid tumor indications.

479 AGEN1181, an Fc-enhanced anti-CTLA-4 antibody, alone and in combination with balstilimab (anti-PD-1) in patients with advanced solid tumors: Initial phase I results

Background

AGEN1181 is a novel anti-CTLA-4 antibody with enhanced FcyR-dependent functionality, engineered to bind high and low binding alleles of FcyRIIIA, promoting superior T cell priming, memory responses, and depletion of intratumoral T regulatory cells. Further, AGEN1181 avoids complement recruitment, predictive of better tolerability. Here we report initial safety and efficacy findings from a phase I/Ib study of AGEN1181 as monotherapy and in combination with balstilimab (BAL; anti-PD-1).

Methods

Eligible patients (pts) had advanced solid tumors refractory to standard therapies. AGEN1181 was dosed Q3W (0.1–3 mg/kg) or Q6W (1–2 mg/kg) as monotherapy, or Q6W (0.1–2 mg/kg) in combination with BAL Q2W (3 mg/kg).

Results

As of July 16th 2021, 102 pts received AGEN1181 (43 monotherapy, 59 combination). Median age, 63 years (29–83); 50.5% with ≥3 prior lines of therapy. MTD not yet reached with AGEN1181 dosing up to 3 mg/kg Q3W as monotherapy and 2 mg/kg in combination with BAL. The most common treatment-related adverse events (TRAEs) of any grade were fatigue (34.3%), diarrhea (32.4%), and nausea (19.6%) with grade ≥3 events in 21.6% (diarrhea/colitis, 11.8%, fatigue, 2.9%). Notably, no immune-related hypophysitis or pneumonitis has been observed. Discontinuation from AGEN1181 due to TRAEs occurred in 15% of pts. Grade 5 TRAEs occurred in two pts (colitis [chronic], intestinal perforation). The disease control rate in evaluable pts (completed ≥1 on-treatment scan) defined as best overall response of CR, PR, or SD ≥6 weeks was 48.1% for AGEN1181 monotherapy ≥1 mg/kg (1 CR, 3 PR, 9 SD) and 70% for combination (3 PR, 6 unconfirmed PR [uPR], 19 SD). Monotherapy responders include individual pts with MSS endometrial cancer (CR), PD-1-relapsed/refractory cervical cancer (PR), PD-1-relapsed/refractory melanoma (PR), and pancreatic cancer (PR). Enrollment is continuing in several disease expansion cohorts with combination therapy. For MSS CRC, 2 PR, 2 uPR, and 7 SD have been seen in 17 evaluable ≥1 mg/kg patients to date. In the ovarian cohort (n=6), 2 PRs and 3 SD are noted. Additional combination responders include one PR and uPR in MSS endometrial cancer, two uPRs in visceral angiosarcoma (uPRs) and one uPR in PD-1-relapsed/refractory NSCLC (uPR); the majority of the responses are recent and ongoing.

Conclusions

AGEN1181 alone and in combination with BAL demonstrates favorable tolerability and compelling clinical activity, notably in poorly immunogenic tumor types and PD-1-refractory pts. These results underscore the significant potential of AGEN1181 to expand benefit of anti-CTLA-4 therapy to a broader patient population.

Trial Registration

NCT03860272

Ethics Approval

The study obtained ethics approval at each participating center (UT Health Sciences Center at San Antonio, University of Colorado Cancer Center, St John’s Cancer Institute, and HonorHealth under WIRB Study number 1256391; USC Norris Comprehensive Cancer Center, Beth Israel Deaconess Medical Center, and MD Anderson Cancer Center, approval numbers HS19-00277, 19–132, and 140346, respectively). All patients provided written informed consent in accordance with federal, local, and institutional guidelines.

Motixafortide and Pembrolizumab Combined to Nanoliposomal Irinotecan, Fluorouracil, and Folinic Acid in Metastatic Pancreatic Cancer: The COMBAT/KEYNOTE-202 Trial

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is largely unresponsive to checkpoint inhibitors. Blockade of the CXCR4/CXCL12 axis increases intratumoral trafficking of activated T cells while restraining immunosuppressive elements. This study evaluates dual blockade of CXCR4 and PD1 with chemotherapy in PDAC.

PATIENTS AND METHODS

Multicenter, single-arm, phase II study to evaluate the safety and efficacy of motixafortide and pembrolizumab combined with chemotherapy in patients with de novo metastatic PDAC and disease progression on front-line gemcitabine-based therapy (NCT02826486). Subjects received a priming phase of motixafortide daily on days 1-5, followed by repeated cycles of motixafortide twice a week; pembrolizumab every 3 weeks; and nanoliposomal irinotecan, fluorouracil, and leucovorin every 2 weeks (NAPOLI-1 regimen). The primary objective was objective response rate (ORR). Secondary objectives included overall survival (OS), progression-free survival (PFS), disease control rate (DCR), safety, and tolerability.

RESULTS

A total of 43 patients were enrolled. The ORR according to RECISTv1.1 was 21.1% with confirmed ORR of 13.2%. The DCR was 63.2% with median duration of clinical benefit of 5.7 months. In the intention-to-treat population, median PFS was 3.8 months and median OS was 6.6 months. The triple combination was safe and well tolerated, with toxicity comparable with the NAPOLI-1 regimen. Notably, the incidence of grade 3 or higher neutropenia and infection was 7%, lower than expected for this chemotherapy regimen.

CONCLUSIONS

Triple combination of motixafortide, pembrolizumab, and chemotherapy was safe and well tolerated, and showed signs of efficacy in a population with poor prognosis and aggressive disease.

Abstract CT177: A multi-center phase 2a trial of the CXCR4 inhibitor motixafortide (BL-8040) (M) in combination with pembrolizumab (P) and chemotherapy (C), in patients with metastatic pancreatic adenocarcinoma (mPDAC)

Background: Improving outcomes of PDAC with checkpoint inhibitors (CPIs) have been ineffective, underscoring the need to co-target alternative pathways. Preclinical data showed that CXCR4-SDF1 axis modulates the tumor microenvironment (TME) in PDAC and that CXCR4 inhibition enhances T cell access to the TME, increasing tumor sensitivity to CPIs. This was confirmed in the COMBAT Cohort 1 (CC1) study showing that the dual combination M+P increases activated CD8+ T cells and decreases myeloid derived suppressor cells (MDSCs) within the TME. Moreover, our pre-clinical studies showed that adding C to M+P resulted in improved efficacy vs C alone. The COMBAT Cohort 2 (CC2) aims to test the safety and efficacy of the triple combination of M+P+C in 2L mPDAC. Methods: Single arm phase 2a study in mPDAC. In cohort 2, patients with stage IV PDAC at diagnose who had progressed to 1L gemcitabine-based C received 5 days M priming, followed by M BIW + P Q3W plus C [Irinotecan liposomal injection/5-FU/LV (OFL)] Q2W. The primary endpoint was RR. Results: A total of 43 patients with stage 4 PDAC, 98% of whom were diagnosed with stage 4 disease, were enrolled. Median age was 68 (40-85) and 74.4% had liver disease. The safety profile was consistent with the individual profiles of each treatment alone. Of note, the incidence of ≥G3 neutropenia (G3Neu) was 7% and ≥G3 infection was 7%, which is lower than expected for C (OFL) alone (20% and 17%, respectively). The levels of T-cells increased during M priming and returned to normal values, which remained stable across the study despite the OFL treatment. For the evaluable patients (N=38) the ORR was 21.1% with a 13.2% confirmed ORR (defined as two consecutive assessments showing PR) and a 63.2% DCR (PR+SD). Median duration of clinical benefit was 5.6 months. Median OS and PFS were 6.5 months and 4.0 months, respectively (6.6 months and 3.8 months, respectively, for the ITT population). Conclusions: The triple combination of M+P+C is tolerable and shows encouraging results with cORR 13.2%, mPFS 4.0 months and mOS 6.5 months (compared to 7.7%, ~3 months and 4.7 months, respectively, on a historical basis for OFL alone in the stage 4 diagnosis subpopulation). SD of 42.1% and DCR of 63.2% were also higher than historical data on SoC chemotherapy used in 2L patients. The incidence of severe neutropenia and infections is lower than the historical data on C. The results from the CC2 suggest that M+P may expand the efficacy and safety benefit of OFL in PDAC, and warrants further investigation in a randomized study.

Citation Format: Manuel Hidalgo, Teresa Macarulla, Valerya Semenisty, Erkut Borazanci, Jaime Feliu, Mariano Ponz-Sarvise, David Gutierrez Abad, Paul Oberstein, Angela Alistar, Andres Muñoz, Ravit Geva, Carmen Guillén-Ponce, Mercedes Salgado Fernandez, Amnon Peled, Marya Chaney, Irit Glicko-Kabir, Liron Shemesh-Darvish, Debby Ickowicz, Ella Sorani, Shaul E. Kadosh, Abi Vainstein-Haras, Bruno Bockorny. A multi-center phase 2a trial of the CXCR4 inhibitor motixafortide (BL-8040) (M) in combination with pembrolizumab (P) and chemotherapy (C), in patients with metastatic pancreatic adenocarcinoma (mPDAC) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT177.

First-in-human phase 1 trial (DRAGON) of SRK-181, a potential first-in-class selective latent TGFβ1 inhibitor, alone or in combination with anti-PD-(L)1 treatment in patients with advanced solid tumors

TPS3146

Background: Transforming growth factor-beta 1 (TGFβ1) is a key mediator of primary resistance to programmed cell death protein 1 (PD-1) pathway blockade. SRK-181 is a fully human, highly potent and selective monoclonal antibody that inhibits latent TGFβ1 activation. SRK-181 has minimal or no binding to latent TGFβ2 and TGFβ3 isoforms or to active TGFβ growth factors. In mouse tumor models (bladder, melanoma, and breast cancer), SRK-181 in combination with anti-PD1 therapy overcame primary anti-PD-1 resistance and showed survival benefit. No cardiotoxicities (valvulopathy) were observed with SRK-181 in 4-week GLP nonclinical toxicology studies. Thus, the potency and selectivity of SRK-181 may overcome PD-1 inhibitor resistance and toxicity of non-selective TGFβ pathway approaches. Methods: The DRAGON trial NCT04291079 is an ongoing multicenter, open-label, phase 1 study of SRK-181 administered by IV infusion every 3 weeks (Q3W) alone or in combination with anti-PD-(L)1 in patients (pts) with locally advanced or metastatic solid tumors. The study comprises 3 parts: Part A of the study follows a standard 3+3 dose escalation trial design to evaluate safety, tolerability, pharmacokinetics (PK), pharmacodynamics (PD) and antitumor activity of SRK-181 alone (Part A1) or in combination with the anti-PD-(L)1 agent that is approved for the respective tumor indication (Part A2). Part A1 and Part A2 will determine maximum tolerated dose (MTD) or maximum administered dose and Recommended Phase 2 Dose (RP2D) for Part B. Part B (expansion phase) will evaluate combination treatment of SRK-181 with anti-PD-(L)1 in pts with non-small cell lung cancer, urothelial carcinoma (UC), melanoma or other advanced solid tumors, to confirm the tolerability of the RP2D and to evaluate the antitumor activity of combination treatment. Pts in Part A2 and Part B must have previously received an anti-PD-(L)1 therapy approved in their tumor indication and considered non-responders (best response of stable disease or disease progression) to anti-PD-(L)1 monotherapy. Pts in Part B must have received the most recent dose of the prior anti-PD-(L)1 within 6 months of study enrollment (9 months for UC cohort). Safety, PK, PD and efficacy data will be collected and monitored throughout the study. Detailed translational PD and predictive biomarker studies for SRK-181 will include a novel digital pathology analysis of CD8 to assess the alteration of immune profile in tumor microenvironment and TGFb pathway biomarkers, such as quantitative analysis of tumor phospho-Smad2 and circulating levels of TGFb1 ligand. As of Feb 01 2021, dose escalation has proceeded to the highest planned dose of 2400 mg Q3W in Part A1 (monotherapy) and to 800 mg Q3W in Part A2 (anti-PD-(L)1 combination). Additional planned doses in Part A2 are 1600 mg and 2400 mg Q3W. Clinical trial information: NCT04291079.

PDX-derived organoids model in vivo drug response and secrete biomarkers

Patient-derived organoid models are proving to be a powerful platform for both basic and translational studies. Here we conduct a methodical analysis of pancreatic ductal adenocarcinoma (PDAC) tumor organoid drug response in paired patient-derived xenograft (PDX) and PDX-derived organoid (PXO) models grown under WNT-free culture conditions. We report a specific relationship between area under the curve value of organoid drug dose response and in vivo tumor growth, irrespective of the drug treatment. In addition, we analyzed the glycome of PDX and PXO models and demonstrate that PXOs recapitulate the in vivo glycan landscape. In addition, we identify a core set of 57 N-glycans detected in all 10 models that represent 50%-94% of the relative abundance of all N-glycans detected in each of the models. Last, we developed a secreted biomarker discovery pipeline using media supernatant of organoid cultures and identified potentially new extracellular vesicle (EV) protein markers. We validated our findings using plasma samples from patients with PDAC, benign gastrointestinal diseases, and chronic pancreatitis and discovered that 4 EV proteins are potential circulating biomarkers for PDAC. Thus, we demonstrate the utility of organoid cultures to not only model in vivo drug responses but also serve as a powerful platform for discovering clinically actionable serologic biomarkers.

Abstract CT119: Organoid sensitivity in pancreatic cancer correlates with clinical response to treatment and reveals utility for reducing toxicity: Preliminary results from the HOPE trial

The HOPE trial (Harnessing Organoids for PErsonalized Therapy) was a pilot study to test the feasibility of generating patient derived organoids (PDOs) from patients with pancreatic cancer under real world conditions, test drug sensitivity against these PDOs, and correlate these findings with clinical outcomes. Biopsies were obtained primarily during routine clinical care from surgical specimens, ascites, fine needle biopsies (FNB) of primary tumors, and IR guided core biopsies of liver and lymph node metastases. PDOs were grown in WNT free media according to our previously published methods. PDO drug sensitivity testing was performed on a panel of drugs, AUC calculated, and sensitivity ranked. Patients were followed clinically and assessed for disease control. At data cutoff (January 2020), we enrolled a total of 76 subjects representing all stages of disease. Drug testing was performed successfully on PDOs generated from 12 of these subjects (16%). Factors contributing to success obtaining sufficient cells for PDO generation included modality, body part, and tumor cellularity. H&E and IHC corresponded in matched PDOs and donor tumors, as did DNA alterations. Transcriptomes of PDOs were classified as both ‘basal' and ‘classical' subtypes. When AUC values were annotated with clinical data, the Jenks break of 1.69 segregated matched PDO/AUC values into disease control and progressive disease. We estimated that a PDO AUC value <1.66 yields a > 99% probability of disease control from a regimen that contains this drug, whereas if all drugs in a regimen had an AUC > 2.75 there is a > 80% probability of accurately predicting resistance. To illustrate the potential of PDO testing to tailor treatment for an individual patient, we described a case of a subject with stage IV PDAC with a KRAS mutation and ERBB2 amplification. The subject had disease control with FOLFIRINOX, which was held for toxicity. The PDO showed resistance to oxaliplatin and the patient subsequently had an extended period of disease control with regimens which did not include oxaliplatin, highlighting the potential of PDO drug sensitivity testing to exclude ineffective treatments from combination chemotherapy and limit toxicity. In conclusion, we have shown the feasibility of collecting material via real-world clinical practice sufficient to develop PDOs suitable for rapidly screening multiple drugs, and have shown a high degree of correlation between clinical outcomes in patients with PDAC and matched PDO drug sensitivity. We determined preliminary criteria based on the AUC of individual drugs in PDOs to predict drug sensitivity in subjects. These results highlight the potential of PDOs to personalize therapy and allow for the exclusion of ineffective drugs from combination regimens thereby reducing toxicity. We anticipate this approach will be used in future trials to prospectively inform treatment selection for patients with PDAC.

Citation Format: Joseph Elan Grossman, Ling Huang, Lakshmi Muthuswamy, Sofia Perea, Dipikaa Akshinthala, Raul Gonzalez, Leo Tsai, Jonah Cohen, Mandeep Sawhney, Douglas Pleskow, Tyler M. Berzin, Bruno Bockorny, Andrea Bullock, Benjamin Schlechter, Mary Linton B. Peters, Catherine Conahan, Supraja Narasimhan, Christine Lim, Roger Davis, Robert Besaw, Martin Smith, Tara Kent, Mark Callery, Senthil K. Muthuswamy, Manuel Hidalgo. Organoid sensitivity in pancreatic cancer correlates with clinical response to treatment and reveals utility for reducing toxicity: Preliminary results from the HOPE trial [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 CT119.

Discovery of New Targets to Control Metastasis in Pancreatic Cancer by Single-cell Transcriptomics Analysis of Circulating Tumor Cells

Metastasis development is the leading cause of cancer-related mortality in pancreatic ductal adenocarcinoma (PDAC) and yet, few preclinical systems to recapitulate its full spreading process are available. Thus, modeling of tumor progression to metastasis is urgently needed. In this work, we describe the generation of highly metastatic PDAC patient-derived xenograft (PDX) mouse models and subsequent single-cell RNA-sequencing (RNA-seq) of circulating tumor cells (CTC), isolated by human HLA sorting, to identify altered signaling and metabolic pathways, as well as potential therapeutic targets. The mouse models developed liver and lung metastasis with a high reproducibility rate. Isolated CTCs were highly tumorigenic, had metastatic potential, and single-cell RNA-seq showed that their expression profiles clustered separately from those of their matched primary and metastatic tumors and were characterized by low expression of cell-cycle and extracellular matrix-associated genes. CTC transcriptomics identified survivin (BIRC5), a key regulator of mitosis and apoptosis, as one of the highest upregulated genes during metastatic spread. Pharmacologic inhibition of survivin with YM155 or survivin knockdown promoted cell death in organoid models as well as anoikis, suggesting that survivin facilitates cancer cell survival in circulation. Treatment of metastatic PDX models with YM155 alone and in combination with chemotherapy hindered the metastatic development resulting in improved survival. Metastatic PDX mouse model development allowed the identification of survivin as a promising therapeutic target to prevent the metastatic dissemination in PDAC.

BL-8040, a CXCR4 antagonist, in combination with pembrolizumab and chemotherapy for pancreatic cancer: the COMBAT trial

Programmed cell death 1 (PD-1) inhibitors have limited effect in pancreatic ductal adenocarcinoma (PDAC), underscoring the need to co-target alternative pathways. CXC chemokine receptor 4 (CXCR4) blockade promotes T cell tumor infiltration and is synergistic with anti-PD-1 therapy in PDAC mouse models. We conducted a phase IIa, open-label, two-cohort study to assess the safety, efficacy and immunobiological effects of the CXCR4 antagonist BL-8040 (motixafortide) with pembrolizumab and chemotherapy in metastatic PDAC (NCT02826486). The primary outcome was objective response rate (ORR). Secondary outcomes were overall survival (OS), disease control rate (DCR) and safety. In cohort 1, 37 patients with chemotherapy-resistant disease received BL-8040 and pembrolizumab. The DCR was 34.5% in the evaluable population (modified intention to treat, mITT; N = 29), including nine patients (31%) with stable disease and one patient (3.4%) with partial response. Median OS (mOS) was 3.3 months in the ITT population. Notably, in patients receiving study drugs as second-line therapy, the mOS was 7.5 months. BL-8040 increased CD8+ effector T cell tumor infiltration, decreased myeloid-derived suppressor cells (MDSCs) and further decreased circulating regulatory T cells. In cohort 2, 22 patients received BL-8040 and pembrolizumab with chemotherapy, with an ORR, DCR and median duration of response of 32%, 77% and 7.8 months, respectively. These data suggest that combined CXCR4 and PD-1 blockade may expand the benefit of chemotherapy in PDAC and warrants confirmation in subsequent randomized trials.

Dose-adjusted enoxaparin thromboprophylaxis in hospitalized cancer patients: a randomized, double-blinded multicenter phase 2 trial

Hospitalized patients with cancer are at an increased risk of developing venous thromboembolism (VTE). The recommendation for routine pharmacologic thromboprophylaxis in hospitalized patients with cancer to prevent VTE is based on extrapolation of results from noncancer cohorts. There are limited data to support the efficacy and safety of fixed-dose low-molecular-weight heparin (LMWH) regimens in high-risk hospitalized patients with cancer. We conducted a randomized, double-blinded, phase 2 trial in hospitalized patients with active cancer at high risk of developing VTE based on Padua risk score. Patients were randomly assigned to fixed-dose enoxaparin (40 mg daily) vs weight-adjusted enoxaparin (1 mg/kg daily) during hospitalization. The primary objectives were to evaluate the safety of dose-adjusted enoxaparin and evaluate the incidence of VTE with fixed-dose enoxaparin. Blinded clinical assessments were performed at day 14, and patients randomly assigned to fixed-dose enoxaparin subsequently underwent a bilateral lower extremity ultrasound. A total of 50 patients were enrolled and randomized. The median weight of patients enrolled in weight-adjusted enoxaparin arm was 76 kg (range, 60.9-124.5 kg). There were no major hemorrhages or symptomatic VTE in either arm. At time of completion of the blinded clinical assessment, there was only 1 incidentally identified pulmonary embolus that occurred in the weight-adjusted arm. In the group randomly assigned to fixed-dose enoxaparin who subsequently underwent surveillance ultrasound, the cumulative incidence of DVT was 22% (90% binomial confidence interval, 0%-51.3%). This phase 2 trial confirms a high incidence of asymptomatic VTE among high-risk hospitalized patients with cancer and that weight-adjusted LMWH thromboprophylaxis is feasible and well-tolerated. This trial was registered at www.clinicaltrials.gov as #NCT02706249.

Phase I, first-in-human study of AbGn-107, a novel antibody-drug conjugate (ADC), in patients with gastric, colorectal, pancreatic or biliary cancers

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Background: AbGn-107 is an ADC directed against AG-7 antigen, a Lewis A-like glycol-epitope expressed in 24-61% of gastric (G), colorectal (CRC), pancreatic (PDA), and biliary (BIL) cancers. Based on promising antitumor activity of AbGn-107 in both in vitro and in vivo preclinical studies, we performed a Phase Ia trial in patients with the aforementioned GI malignancies. Methods: Standard 3+3 dose escalation was used. Key eligibility included locally advanced or metastatic G, CRC, PDA, or BIL cancer, previously treated, ECOG PS 0-1; positive AG-7 expression was not required. Two dosing intervals were tested: AbGn-107 administered i.v. Q4 weeks (at doses ranging from 0.1-1.2 mg/kg) and Q2 weeks (at doses from 0.8-1.0 mg/kg). Dose limiting toxicities (DLT) were based on grade 3/4 hematologic and non-heme AEs occurring during the initial 4-week rx window. Patients were treated until disease progression or unacceptable toxicity, with tumor assessments Q8 weeks. 1o objectives: safety and MTD; 2o objectives: PK, immunogenicity, and efficacy defined by ORR (RECIST 1.1). Results: 35 patients were enrolled across 6 dose levels (median age 61.5 yo (range 40 – 81); G (0)/CRC (12)/PDA (20)/BIL (3); median # lines of prior rx = 3 (range 1-7). Safety: 5 patients experienced Grade 3 or 4 neutropenia, all at higher dose levels, inc. 1 episode of febrile neutropenia. Other frequent drug-related AEs, mostly grade 1/2, inc. fatigue (29%), nausea (20%), and diarrhea (14%). DLTs included grade 4 CK elevation (n = 1) at 0.8 mg/kg Q4W and grade 3 arthralgias (n = 1) at 1.2 mg/kg Q4W. Based on safety profile and PK data, 1.0 mg/kg Q2W was selected as the dose schedule for cohort expansion phase. Efficacy: Median duration of treatment = 56 days (range, 8 – 225 days). Six pts have demonstrated a minor response by RECIST (range, -1.3 to -21.1%); 4 pts (all PDA) have had durable dz control > 180 days. Conclusions: Overall, AbGn-107 appears well-tolerated with encouraging prelim signs of efficacy in unselected pts with heavily pre-treated advanced GI cancers. Updated safety and efficacy data will be provided at the time of the meeting for the cohort expansion phase of this study (currently open across multiple sites in U.S. and Taiwan), in which subjects with G, CRC, PDA, and BIL cancers are pre-screened for high levels of AG-7 tumor expression. Clinical trial information: NCT02908451 .

GI oncology molecular tumor board: Fostering collaboration and clinical education for personalized therapy

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Background: In recent years, genomic profiling has become standard of care for several gastrointestinal (GI) cancers. In addition to standard of care indications, comprehensive genomic profiling has led to novel and expanded applications of targeted therapy, chemotherapy, and immunotherapy and facilitated identification of potential clinical trials. A GI molecular tumor board (MTB) was developed with a goal of improving understanding of the biological effects of genomic alterations and their therapeutic implications to enhance personalized therapy. Methods: Foundation Medicine (FM) collaborated with physicians in the GI oncology group of an academic medical center to develop a GI MTB starting March 2019. As of December 2019, 27 GI oncology cases were presented where FoundationOneCDx testing was performed and a clinical question was posed. Cases were discussed by faculty, fellows, research staff, and a clinical genomic scientist and oncologist from FM. Impacted signaling pathways and biomarkers were discussed for each case alongside clinical content so that physicians could consider therapeutic options and clinical trials. Presenting faculty were asked to complete a questionnaire for each case presented to assess the impact of the MTB discussion on clinician knowledge and patient-level treatment recommendations. Results: Of 27 questionnaires sent to 7 providers, 17 (63%) were completed. Respondents indicated that as a result of the MTB, the treatment plan was changed in 2 cases (12%), reinforced in 9 cases (53%) and in 6 cases (35%) there was no effect. On a Likert scale of 1-4 where 1 is “rare/poorly” and 4 is “great” mean scores were as follows: Did this MTB help you understand the biological effects of the main genomic alteration(s) reported in the case presented? 3.3. Did this MTB help you understand the possible therapeutic implications of the main genomic alterations in the case presented? 3.3. Did this MTB improve your understanding of the role of next generation sequencing and comprehensive genomic profiling in making treatment decisions? 3.4. Conclusions: The results of our questionnaire indicate that treatment decisions were changed in a minority of cases based on the MTB. In most cases, clinical decision making was reinforced and understanding of the biological effects of genomic alterations and their therapeutic implications were improved. Based on this feedback we will continue to refine and integrate the GI MTB into clinical care for patients with GI malignancies, and share our experience locally with other disease groups.

OMTX705, a Novel FAP-Targeting ADC Demonstrates Activity in Chemotherapy and Pembrolizumab-Resistant Solid Tumor Models

PURPOSE

The tumor microenvironment plays a key role in cancer development and progression and is involved in resistance to chemo- and immunotherapy. Cancer-associated fibroblast expressing fibroblast-activating protein α (FAPα) is one of the predominant stroma cell types and is involved in resistance to immunotherapy.

EXPERIMENTAL DESIGN

We generated OMTX705, a novel antibody-drug conjugate from a humanized anti-FAP antibody linked to a new cytolysin. Here, we studied its antineoplastic activity in vitro and in preclinical mouse models alone and in combination with chemotherapy as well as immunotherapy in PD-1-resistant tumors.

RESULTS

In Avatar models, OMTX705 showed a 100% tumor growth inhibition and prolonged tumor regressions as single agent and in combination with chemotherapy. Treatment rechallenge following treatment discontinuation induced additional tumor regression, suggesting lack of treatment resistance. In a mouse model with a humanized immune system resistant to PD-1 inhibition, OMTX705 increased tumor infiltration by CD8⁺ T cells, induced complete regressions, and delayed tumor recurrence.

CONCLUSIONS

These data suggest that FAP targeting with OMTX705 represents a novel and potent strategy for cancer treatment, including tumors resistant to immunotherapy, and support its clinical development.

RAS-MAPK Reactivation Facilitates Acquired Resistance in FGFR1-Amplified Lung Cancer and Underlies a Rationale for Upfront FGFR-MEK Blockade

The FGFR kinases are promising therapeutic targets in multiple cancer types, including lung and head and neck squamous cell carcinoma, cholangiocarcinoma, and bladder cancer. Although several FGFR kinase inhibitors have entered clinical trials, single-agent clinical efficacy has been modest and resistance invariably occurs. We therefore conducted a genome-wide functional screen to characterize mechanisms of resistance to FGFR inhibition in a FGFR1-dependent lung cancer cellular model. Our screen identified known resistance drivers, such as MET, and additional novel resistance mediators including members of the neurotrophin receptor pathway (NTRK), the TAM family of tyrosine kinases (TYRO3, MERTK, AXL), and MAPK pathway, which were further validated in additional FGFR-dependent models. In an orthogonal approach, we generated a large panel of resistant clones by chronic exposure to FGFR inhibitors in FGFR1- and FGFR3-dependent cellular models and characterized gene expression profiles employing the L1000 platform. Notably, resistant clones had enrichment for NTRK and MAPK signaling pathways. Novel mediators of resistance to FGFR inhibition were found to compensate for FGFR loss in part through reactivation of MAPK pathway. Intriguingly, coinhibition of FGFR and specific receptor tyrosine kinases identified in our screen was not sufficient to suppress ERK activity or to prevent resistance to FGFR inhibition, suggesting a redundant reactivation of RAS-MAPK pathway. Dual blockade of FGFR and MEK, however, proved to be a more powerful approach in preventing resistance across diverse FGFR dependencies and may represent a therapeutic opportunity to achieve durable responses to FGFR inhibition in FGFR-dependent cancers. Mol Cancer Ther; 17(7); 1526-39. ©2018 AACR.

Suppression of Adaptive Responses to Targeted Cancer Therapy by Transcriptional Repression

Acquired drug resistance is a major factor limiting the effectiveness of targeted cancer therapies. Targeting tumors with kinase inhibitors induces complex adaptive programs that promote the persistence of a fraction of the original cell population, facilitating the eventual outgrowth of inhibitor-resistant tumor clones. We show that the addition of a newly identified CDK7/12 inhibitor, THZ1, to targeted therapy enhances cell killing and impedes the emergence of drug-resistant cell populations in diverse cellular and in vivo cancer models. We propose that targeted therapy induces a state of transcriptional dependency in a subpopulation of cells poised to become drug tolerant, which THZ1 can exploit by blocking dynamic transcriptional responses, promoting remodeling of enhancers and key signaling outputs required for tumor cell survival in the setting of targeted therapy. These findings suggest that the addition of THZ1 to targeted therapies is a promising broad-based strategy to hinder the emergence of drug-resistant cancer cell populations.Significance: CDK7/12 inhibition prevents active enhancer formation at genes, promoting resistance emergence in response to targeted therapy, and impedes the engagement of transcriptional programs required for tumor cell survival. CDK7/12 inhibition in combination with targeted cancer therapies may serve as a therapeutic paradigm for enhancing the effectiveness of targeted therapies. Cancer Discov; 8(1); 59-73. ©2017 AACR.See related commentary by Carugo and Draetta, p. 17This article is highlighted in the In This Issue feature, p. 1.

Abstract 15: Suppression of adaptive responses to targeted therapies by transcriptional inhibition

Tumor cells become dependent on the expression of key genes that drive hallmark tumor traits, but these “addictions” also represent potential vulnerabilities for therapeutic intervention. Treating tumor cells with a small molecule inhibitor of the transcriptional kinase CDK7 selectively suppresses expression of key dependency genes in multiple cancers. Our previous work showed responses to the CDK7 inhibitor THZ1 were especially noteworthy in T cell leukemias, small cell lung cancers, and triple-negative breast cancers—tumor types where the prognoses are especially unfavorable. The genes whose expression is most sensitive to CDK7 inhibition and whose expression is essential for tumor cell survival are often associated with super-enhancers—clusters of constituent enhancers that are bound by unusually large amounts of transcription apparatus including CDK7 itself. This “Achilles’ cluster” of super-enhancer-associated genes thus represents the set of addictions of tumor cells whose expression is important for tumor cell survival. Transcriptional inhibition synergizes with targeted therapies in models of multiple tumor types. Treating tumors with therapies that target kinase proteins such as EGFR, FGFR, and KRAS leads to resistance, which is concurrent with changes in the activities of enhancers and super-enhancers and gene expression programs of resistant cells. Treating cells with a transcriptional inhibitor in addition to targeted therapies prevents “rewiring” of the gene expression program and increases cell death in tumor models. Thus transcriptional inhibition represents a promising avenue in both monotherapy and combination settings where drug resistance is acquired.

Citation Format: Maria Rusan, Kapsok Li, Yvonne Li, Camilla L. Christensen, Brian J. Abraham, Nicholas Kwiatkowski, Kevin Buczkowski, Bruno Bockorny, Ting Chen, Shuai Li, Haikuo Zhang, Hideko Terai, Tiffany Tavares, Tinghu Zhang, Tae Jung Kim, Michael Silkes, Tenny Mudianto, Li Tan, Takeshi Shimamura, Matthew Meyerson, Hideo Watanabe, Nathanael S. Gray, Richard A. Young, Kwok-Kin Wong, Peter S. Hammerman. Suppression of adaptive responses to targeted therapies by transcriptional inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 15. doi:10.1158/1538-7445.AM2017-15

Enhancing targeted therapy of tumors with activating FGFR alterations

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Background: Emerging evidence points to the Fibroblast Growth Factor Receptor (FGFR) kinase family as a promising target in multiple cancer types including lung squamous cell carcinoma, cholangiocarcinoma, gastric, bladder and breast cancer. Although several FGFR kinase inhibitors have entered clinical trials, single agent clinical efficacy has been modest and resistance invariably occurs. A comprehensive understanding of the molecular basis of resistance to FGFR inhibitors is urgently needed to enable the successful application of anti-FGFR therapy in the clinic. Methods: We utilized a systematic genome-wide open reading frame (ORF) screen to identify genes whose upregulation confers resistance to the FGFR inhibitors BGJ398 and FIIN-3 in FGFR1-amplified H2077 lung cancer cells. In an orthogonal approach, we established resistant clones of FGFR1-amplified and FGFR3-translocated cell lines by chronic exposure to BGJ398, and characterized these by high-throughput gene expression analysis. Results: We identified 34 candidate genes, including expected findings such as a mutant KRAS allele and MET overexpression. Intriguingly, we also identified novel candidate resistance mechanisms involving the genes of the TAM family, which encode the transmembrane receptors Tyro3, Axl and Mertk. These tyrosine kinases may serve as a secondary target to augment FGFR therapy. We validated that the TAM family confers resistance to FGFR inhibitors in different FGFR dependencies including FGFR1-amplified lung cancer, FGFR2-amplified gastric and colon cancer and FGFR 3-translocated bladder cancer, with AXL having the greatest rescue. Notably, gene profiling of resistant clones also implicates the TAM family, with both receptors and their ligands upregulated in the majority cases. Moreover, concurrent TAM blockade augments the response to FGFR inhibition in vitro and provides a promising therapeutic strategy to overcome resistance. Conclusions: TAM kinases are important mediators of resistance to FGFR inhibitors and the dual blockade of FGFR and TAM provides a novel approach to enhance the efficacy of anti-FGFR therapy.

The emerging role of immunotherapy in gastric and esophageal adenocarcinoma

Gastric and esophageal adenocarcinomas are aggressive malignancies. Systemic therapy for these tumors relies primarily on cytotoxic chemotherapy but outcomes remain poor. In recent years, immunotherapy has emerged as a new, promising therapeutic approach for a variety of solid tumors. Characterization of gastroesophageal cancers has revealed genomic and immune features of these tumors that may predict response to immunotherapy. Indeed, preliminary results from the initial trials of immune checkpoint inhibitors have been encouraging, with objective response rates of 20% in heavily pretreated patient populations. Based on these results, additional trials of single-agent checkpoint inhibitors as well as combinations with chemotherapy and targeted therapies are currently ongoing. Further work to identify predictive biomarkers will be crucial for the successful implementation of immunotherapy.

Prevalence and Pattern of Autoimmune Conditions in Patients with Marginal Zone Lymphoma: A Single Institution Experience

BACKGROUND

Increased risk of B-cell non-Hodgkin lymphoma (NHL) in patients with autoimmune diseases is a known fact. An association may exist between marginal zone lymphoma (MZL) and certain autoimmune conditions and vice-versa.

METHODS

Herein, we present the analysis of a series of consecutive patients (n = 24) diagnosed with MZL at our institution between 2008-2014. Our series, analyzed both retrospectively and prospectively, consisted of a blend of nodal, extranodal and splenic MZL. The median age was 71.8 years; M/F ratio was 2:1. The presence of autoimmune conditions was compared to their documented prevalence in the general population and tested for statistical significance using both chi-square test (χ2) and Fisher test for small number of observations (95% confidence). A P-value < 0.05 was considered significant.

FINDINGS

A total of 50% of MZL patients had documented autoimmune conditions. In addition, 3 of 24 patients presented with more than one autoimmune disease. Statistically significant differences in our MZL patients were recorded for immune thrombocytopenia [ITP] (P < 0.01), autoimmune hemolytic anemia [AIHA] (P < 0.01), Hashimoto thyroiditis (P = 0.037) and rheumatoid arthritis [RA] (P = 0.021). The difference did not reach statistical significance for systemic lupus erythematosus (SLE) and psoriasis. ITP and AIHA in our cohort were synchronous with MZL diagnosis in all patients, while all non-hematologic autoimmune conditions were metachronous and diagnosed prior to MZL.

CONCLUSIONS

In the course of caring for patients with MZL, a number of associated autoimmune disorders are recognized. Knowing these entities is important not only for making a correct diagnosis, but also for being able to recognize certain clinical events occurring during the course of the disease. A catalogue of autoimmune disorders associated with this type of NHL is important as they can pose formidable clinical problems for the MZL patients and their physicians.

HMG-CoA reductase inhibitors as adjuvant treatment for hematologic malignancies: what is the current evidence?

Statins have been shown to possess properties that go beyond their lipid-lowering effects. These agents act on the mevalonate pathway and inhibit synthesis of cholesterol, geranylgeranyl pyrophosphate, and farnesyl pyrophosphate, which are necessary for posttranslational modification of the Rho, Rac, and Ras superfamily of proteins. Early phase studies have demonstrated that this modulation of cellular signaling can ultimately exert pro-apoptotic, anti-angiogenic, and immunomodulatory effects, and might even restore chemosensitivity in several hematologic cancers. Nonetheless, these promising preclinical results have not yet migrated from the bench to the bedside as their effectiveness as adjuvant agents in hematologic malignancies is currently uncertain. In the present review, we summarize the existing evidence stemming from preclinical and clinical studies pertaining to the use of statins as adjuvant therapies in hematologic malignancies, and discuss the new insights gained from the ongoing translational research.

Pyoderma gangrenosum due to lenalidomide use for multiple myeloma

Pyoderma gangrenosum has been described in association with multiple myeloma and usually affects patients with active/untreated disease. This dermatologic condition was shown to resolve after successful anti-myeloma therapy. We report herein occurrence of pyoderma gangrenosum involving bilateral knees in a patient with multiple myeloma responding to lenalidomide therapy. Previous papers claimed usefulness of thalidomide and its newer derivatives for the therapy of this neutrophilic dermatosis. Occurrence of pyoderma gangrenosum in a myeloma patient responding to lenalidomide would argue against its effectiveness in treating this skin condition. Moreover, the clinical setting suggested that lenalidomide either induced or contributed to the occurrence of pyoderma gangrenosum in our patient. If our hypothesis is correct, we expect more reports of pyoderma gangrenosum with the use of this class of pharmaceuticals.

Recurrent pseudocellulitis due to gemcitabine: underrecognized and underreported?

Pseudocellulitis has been previously described with the use of chemotherapy agent gemcitabine. This condition is thought to occur due to vascular toxicity and increased localized permeability of the skin capillaries. We report herein a case of recurrent pseudocellulitis due to gemcitabine in a patient with metastatic pancreatic cancer. We believe this condition is underreported and underrecognized. Furthermore, it may be misdiagnosed as cellulitis and inappropriately treated with systemic antibiotics. As the diagnosis is clinical and the condition is self-limited, referral to other specialists is usually not required. Awareness of gemcitabine-induced pseudocellulitis is important in order to reassure the patients, their families, and non-oncology providers and to avoid unnecessary (and often costly) diagnostic work-up.

Pulmonary hemorrhage with capillaritis secondary to mycophenolate mofetil in a heart-transplant patient

Immunosuppressive drugs are an integral part of therapy in organ transplantation. However, they are not without side effects, and although rare, these agents should be considered in the differential diagnosis of pulmonary complications in patients receiving transplants. We present a case of a patient who developed acute respiratory failure 7 days after orthotopic heart transplantation and who had been on both mycophenolate mofetil (MMF) and tacrolimus agents. Lung biopsy revealed features of pulmonary hemorrhage with capillaritis. Considered as a possible etiology, MMF was withdrawn. There was immediate improvement of the patient's symptoms. The temporal relationship between MMF exposure and onset of pulmonary symptoms in the absence of other possible etiologies strongly suggests a causal relationship. Previously published reports of pulmonary toxicity from MMF included interstitial fibrosis. To the best of our knowledge, this is the first reported case of pulmonary hemorrhage with capillaritis because of administration of MMF.

Methotrexate therapy leading to a rapid progression of a previously indolent prostate cancer: is immunosuppression to blame?

Methotrexate therapy has been associated with occurrence and/or accelerated progression of malignancies. We describe a patient who developed widespread bone metastases of a previously confined to the prostate gland prostate cancer shortly after starting methotrexate therapy for rheumatoid arthritis and large granular lymphocyte leukemia. We believe an immunosuppressive milieu brought on by the methotrexate use in this case is responsible for the rapid progression of prostate cancer leading to the patient's demise. To the best of our knowledge, no association has been made to date between the therapy with methotrexate and a fulminant course of a previously indolent prostate cancer. Given its utilization in a variety of benign and malignant conditions and the ageing population, caution is advised with the use of this agent, especially in the presence of an underlying malignancy.

Intrinsic immune alterations in renal cell carcinoma and emerging immunotherapeutic approaches

INTRODUCTION

Individuals affected by kidney cancer present a variety of immune abnormalities including cellular immune dysfunction, cytokine alterations and antigen presentation defects. On the other hand, spontaneous remissions are seen in up to 4% of renal cell carcinoma (RCC) patients and they are thought to occur via immune mechanisms.

AREAS COVERED

The authors comprehensively review the immune abnormalities in RCC patient and describe the kidney cancer immunotherapy candidates that are most advanced in their clinical development. Most relevant publications were identified through searching the PubMed database; the obtained information was thoroughly analyzed and synthesized.

EXPERT OPINION

As cure in advanced RCC cannot be accomplished with the current therapy standards such as tyrosine kinase inhibitors and mammalian target of rapamycin inhibitors, new treatment strategies are being sought. Enhancing the immune system represents an appealing avenue for kidney cancer therapy. Disappointingly, high-dose interleukin-2 and interferon-α cause severe toxicity and produce a questionable clinical benefit. The authors postulate that the 'durable responses' seen with these agents in only a handful of RCC patients represent spontaneous remissions. Promising immune strategies in RCC such as anti-cytotoxic T-lymphocyte-associated protein antibodies, anti-programmed cell death 1 (PD1)/PD1 ligand and tumor vaccines may expand the existing options for kidney cancer in future years.

Autoimmune manifestations in large granular lymphocyte leukemia

Large granular lymphocyte (LGL) leukemia features a group of indolent lymphoproliferative diseases that display a strong association with various autoimmune conditions. Notwithstanding, these autoimmune conditions have not been comprehensively characterized or systematized to date. As a result, their clinical implications remain largely unknown. The authors offer a comprehensive review of the existing literature on various autoimmune conditions documented in the course of T-cell LGL (T-LGL) leukemia. Though some of them are thought be secondary to the LGL leukemia, others could be primary and might even play a role in its pathogenesis. A considerable clinico-laboratory overlap between T-LGL leukemia associated with rheumatoid arthritis and Felty's syndrome suggests that they are just different eponyms for the same clinical entity.

Prevalence of autoimmune conditions in patients with marginal zone lymphoma: Exploratory analysis of a series of consecutive patients

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Background: Recent literature suggests that an association exists between marginal zone lymphoma (MZL) and certain autoimmune conditions. Furthermore, MZL and autoimmune diseases may share same pathogenesis in these patients. The present study was set to identify the prevalence of autoimmune phenomena in MZL patients and compare it with same in general population. Methods: We conducted both retrospective and prospective analyses in a series of consecutive patients (n=24) with MZL that had been followed in outpatient setting. Median age was 71.8 years (range, 50-96). Records were reviewed for the presence of autoimmune abnormalities; length of the prospective analysis segment was ~24 months. Prevalence of autoimmune disorders in our cohort was compared to their respective prevalence in general population. Statistical analysis: The obtained values were tested for statistical significance using Fisher’s exact test for small number of observations (95% confidence); a p-value < 0.05 was considered significant. Results: A total of 50% patients included in our study had documented autoimmune conditions. Identified autoimmune disorders included Hashimoto thyroiditis (n=5), immune thrombocytopenia [ITP] (n=4), rheumatoid arthritis [RA] (n=1), Raynaud's phenomena (n=1), psoriasis (n=1), and autoimmune hemolytic anemia [AIHA] (n=1). Statistical analysis showed the following significance: Hashimoto thyroiditis (p=0.037), ITP (p<0.01), AIHA (p<0.01), RA(p=0.351), psoriasis (p=0.479), and Raynaud's phenomena (p=0.666). Conclusions: Circa half of MZL patients also have autoimmune conditions, thus significantly exceeding the overall prevalence in general population. Statistically significant differences in our MZL patients were recorded for Hashimoto thyroiditis, ITP, and AIHA. When compared to the prevalence in general population, the difference did not reach statistical significance for RA, psoriasis, and Raynaud's phenomena. However, this may be related to the relatively small size of the analyzed cohort. Therefore, larger studies would be useful before definitive conclusions can be drawn.

Prevalence of autoimmune manifestations in patients with large granular lymphocytic leukemia: Exploratory analysis of a series of consecutive patients

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Background: Review of literature suggests certain autoimmune abnormalities to accompany LGL leukemia. The present study was set to identify the prevalence of autoimmune phenomena in LGL leukemia patients and compare it with same in general population. Methods: We conducted both retrospective and prospective analyses in a series of consecutive patients (n=11) with LGL leukemia that had been followed in outpatient setting. Median age was 71 years ( ± 14 years). The presence of associated autoimmune disorders in our cohort was compared to the published prevalence of these conditions in general population. Statistical analysis: The obtained values were tested for statistical significance using Fisher’s exact test for small number of observations (95% confidence); a p value < 0.05 was considered significant. Results: A total of 45% patients in our study were diagnosed with autoimmune conditions. Identified autoimmune disorders included rheumatoid arthritis [RA] (n=3), Hashimoto thyroiditis (n=3), Felty syndrome (n=1), aplastic anemia (n=1), pernicious anemia (n=1), and leukocytoclastic vasculitis (n=1). Statistical analysis showed the following significance: Hashimoto thyroiditis (p=0.044), RA (p=0.003), Felty syndrome (p<0.001), aplastic anemia (p<0.001), pernicious anemia (p<0.001), and leukocytoclastic vasculitis (p<0.001). Statistical difference was also noted for autoimmune serologic abnormalities, with ANA positivity present in 63.6% of the cases (p< 0.001) and RF present in 50% of the patients (p=0.005). Conclusions: Nearly half of LGL leukemia patients in our cohort had autoimmune conditions, thus significantly exceeding the overall prevalence in general population. Statistically significant differences were recorded for RA, Hashimoto thyroiditis, Felty syndrome, aplastic anemia, pernicious anemia, leukocytoclastic vasculitis, ANA and RF positive serologies. The prevalence of Hashimoto thyroiditis and ANA positivity in our patient cohort was significantly higher than the one in existing literature. Given the relatively small size of the analyzed cohort, larger studies are expected to confirm our findings.