Radiographic Response Research Articles

Abstract B026: Dissecting the pancreatic cancer microenvironment using landscape ecology

Abstract Pancreatic ductal adenocarcinoma (PDAC) is predicted to be the second cause of cancer death in the US by 2040. Five-year overall survival is only ~12% despite decades of research. The mainstay of treatment remains chemotherapy in the absence of highly recurrent, therapeutically actionable, genetic targets. For the minority of patients (~15-20%) who are candidates for curative-intent surgical resection, six months of intensive neoadjuvant chemotherapy with/without chemoradiation has become standard-of-care. However, despite evidence of radiographic, metabolic, and biochemical responses, significant viable residual disease on pathologic analysis is almost universally observed with approximately 40-60% risk of disease recurrence. Thus, there is a critical need to better understand why PDAC remains recalcitrant to current therapeutic modalities. Pathologic evaluation of PDAC reveals a complex microenvironment consisting of neoplastic cells dynamically interacting with both “normal” cellular (e.g. mesenchymal, immune) and non-cellular (e.g. collagen) stromal elements. While biologically important, experimental models and small-scale efforts to dissect the PDAC ecosystem are limited by focus on individual tumor compartments and generation of conflicting results. Consequently, there is a need for a more comprehensive understanding of the structure and dynamics of the PDAC TME through the theoretical lens of evolutionary ecology. Current therapies are not focused on the PDAC ecosystem. We hypothesize that cell-cell interactions of PDAC cells with its local niche are important for conferring treatment resistance. Thus, better understanding of said interactions could yield novel ecologically-informed therapies. Consequently, we developed a digital pathology library of approximately 1000 PDAC resection cases (whole-slide H&E images) performed at Mayo Clinic between 2013-2021. Approximately 400 cases are treatment naive while about 600 were treated with neoadjuvant therapy. While some qualitative features of pathologic analysis have prognostic value (e.g., pathologic treatment response, presence of perineural or lymphovascular invasion, extent of desmoplasia), we aim to identify prognostic spatial relationships using tools from landscape ecology. We utilized the HoVer-Net model for nuclei segmentation and classification and spatial statistics methods and landscape fragmentation analysis to understand the spatial organization within the PDAC tumor ecology. With these methodologies, we can assess the spatial context of cell interactions, habitat/niche/microenvironment formation, ecological relationships between cell populations, and the different tissue components. The different spatial statistics/metrics are used to quantify levels of immune cell infiltration, mixing, as well as the complexity and diversity of microenvironment phenotypes leading to high levels of tumor heterogeneity. Such measurements can help predict the likelihood of a PDAC tumor adaptive potential that could lead to fast evolutionary responses to therapy, progression, and poor prognosis. Citation Format: Merih D. Toruner, Luis Cisneros, Zafar Siddiqui, Chady Meroueh, Ritambhara Singh, Carlo Maley, Martin E. Fernandez-Zapico, Ryan M. Carr. Dissecting the pancreatic cancer microenvironment using landscape ecology [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Translating Cancer Evolution and Data Science: The Next Frontier; 2023 Dec 3-6; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(3 Suppl_2):Abstract nr B026.

Lurbinectedin in prostatic small cell and neuroendocrine carcinoma.

164 Background: Lurbinectedin (L) is a novel inhibitor of oncogenic transcription that was granted accelerated approval by the Food and Drug Administration in June 2020 for the treatment of metastatic small cell lung cancer (SCLC) following disease progression on or after platinum-based chemotherapy (PBC). Prostatic small cell or neuroendocrine carcinoma (SC/NEPC) is a high-grade, invasive malignancy that accounts for < 1% of all prostate cancers. SC/NEPC is distinct from prostatic adenocarcinoma and behaves similar to SCLC. NCCN guidelines for SC/NEPC recommend following the SCLC treatment guidelines. Using these guidelines, L may be used as a second-line treatment in patients (pts) with SC/NEPC who progress on or after PBC. We aimed to characterize the baseline characteristics, clinical course and therapeutic outcomes of pts treated with L for SC/NEPC. Methods: After IRB approval, 18 cases were gathered from 4 academic oncology centers. Baseline patient data, prior treatments and L treatment outcomes, including best radiographic and serologic responses, overall survival (OS), progression-free survival (PFS) and treatment toxicity were assessed. The Kaplan-Meier method was used to calculate OS and PFS from the L start date. Clinical benefit rate (CBR) included pts with complete response (CR), partial response (PR) and stable disease (SD) on imaging. Results: At the time of first L dose, all had metastatic disease with 2-6 distinct sites of metastases, most commonly bone (14/18, 77.8%), lymph nodes (14/18, 77.8%) and liver (13/18, 72.2%); median age was 63.5 (Range: 53-84); 11 pts (61.1%) had an ECOG 0-1; 4 pts (22.2%) had an ECOG of 2-3. The median total number of systemic therapies administered prior to L was 4 (Range: 2-7). All pts received PBC prior to L. The most common dose of L prescribed was 3.2 mg/m2 every 21 days (15/18, 83.3%). Androgen deprivation therapy was administered in conjunction with L in 9 pts (50%). The median number of cycles of L was 5 (Range: 1-10). L was discontinued due to toxicity in 1 patient (5.6%), disease progression in 10 pts (55.6%), transition to hospice in 2 pts (11.1%), 3 pts (16.7%) died while receiving treatment (not due to L toxicity), and 2 pts (11.1%) remained on L at the time of data reporting. The median OS and PFS from date of first L dose was 6.01 months (0.23 – 16.69) and 3.35 months (0.16 – 7.79), respectively. CBR was 9/16 (56.3%) with partial response in 5 pts (31.3%), stable disease in 4 pts (25%), and progressive disease in 7 pts (43.8%). Two pts did not have post-treatment imaging available to assess response. There were no hospitalizations for L treatment related adverse events (tRAE). The most common tRAE were grade I and II fatigue and anemia; 9 pts (50%) experienced no tRAE. The only grade IV toxicity was neutropenia in 3 pts (16.7%). Conclusions: L is a well-tolerated and active treatment option for patients with SC/NEPC. Prospective studies are needed to determine the role of L in the treatment of SC/NEPC.

Outcomes of patients (pts) with advanced renal cell carcinoma (aRCC) treated with cabozantinib (CABO) after lenvatinib plus pembrolizumab (LEN+PEM).

433 Background: LEN+PEM is an approved first-line therapy for aRCC. In the CLEAR study, it produced a 71% objective response rate (ORR), an 18% complete response rate, and improved progression-free survival (PFS) and overall survival (OS) compared to sunitinib. CABO is approved as second and later line therapy for aRCC. We explored the efficacy of CABO in pts with aRCC after treatment with LEN+PEM. Methods: This is a retrospective study of pts with aRCC who received CABO after LEN+PEM at our institution from 12/2019 to 8/2023. Demographics and clinical data were abstracted from the EMR. A blinded radiologist assessed tumor response using RECIST v1.1. We measured PFS, time on therapy (TOT) and OS from start date of CABO. Results: 22 pts were analyzed (Table 1). Median follow up was 7.7 months (mo); 11 pts received LEN+PEM on the HOPE 111 trial (NCT02501096). Among all 22 pts, 11 (50%) had a partial response (PR), 5 (22.7%) had stable disease (SD), and 6 (27.3%) had progressive disease (PD) on LEN+PEM. Median TOT with LEN+PEM was 7.4 mo (range: 1.8-29). 20 pts (90.9%) discontinued LEN+PEM due to PD, 1 pt (4.5%) due to fatigue, and 1 pt (4.5%) due to elevated liver enzymes. 17 pts received CABO right after LEN+PEM; 3 pts received 1 line and 2 pts received 2 lines of therapy before CABO after LEN+PEM. Of 19 pts with evaluable radiographic response on CABO, 1 pt had a PR (ORR 5.3%, PFS 16.1 mo) and 3 pts had SD for ≥6 mo. Median TOT with CABO was 4.3 mo (range: 0.2-18.2); 13 pts (59.1%) took CABO for ≥4 mo, 7 pts (31.8%) took it for ≥6 mo, of which 3pts receivedpalliative radiation andcontinued CABO therapy beyond PD. Median PFS and median OS with CABO were 4.1 mo (range: 1.2-16.1) and 8.1 mo (range: 0.8-22.5), respectively. At time of analysis, 4 pts were still taking CABO (3 SD, 1 not yet evaluated); 15 pts discontinued CABO: 12 for PD, 1 for Grade 3 hand-foot skin reaction, 1 per pt request, and 1 for transition to hospice; 3 pts died during CABO therapy (bowel obstruction [1], COVID-19 [1], cardiac arrest [1]). Adverse events attributed to CABO were consistent with published reports. Conclusions: In this cohort of heavily pretreated pts who received CABO after LEN+PEM, CABO demonstrated a modest clinical benefit in a minority of pts, underscoring the need to develop effective novel therapies for aRCC. [Table: see text]

Circulating tumor DNA in the surveillance of patients with oligometastatic renal cell carcinoma treated with stereotactic ablative radiation.

477 Background: Oligometastatic renal cell carcinoma (oRCC) patients receiving stereotactic ablative radiation (SAbR) are in need of effective biomarkers beyond imaging to identify those most likely to fail rapidly and therefore would benefit from systemic therapy. Detection of minimal residual disease (MRD) using circulating tumor (ctDNA) is a promising tool to guide decisions in the management of solid tumors. Herein, we investigate the utility of longitudinal ctDNA monitoring to identify high-risk patients. Methods: Patients with oRCC on surveillance after previous SAbR were enrolled in a prospective registry study and longitudinal quantitative ctDNA testing were performed using a tumor-informed commercial ctDNA assay (Signatera). Disease progression was assessed using standard-of-care clinical / radiographic exams and compared to the ctDNA levels that were obtained within the median 32.5 days (IQR 18.5-59) of radiographic exams. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated. Results: The cohort encompassed 17 patients with oRCC (16/17 metachronous >1 year after nephrectomy) who underwent 42 ctDNA measurements between September 2022 and August 2023 with a median of 3 (range 2-6) ctDNA time points per patient. Median follow up after start of ctDNA monitoring was 10.3 months. Seven patients developed radiographic progression at new sites including 6 who received additional SAbR and one who started systemic therapy with interleukin-2. At most recent follow up, 13/17 patients had no radiographic evidence of disease. Out of the 42 ctDNA time points, 11 had detectable ctDNA and 17 had clinical/radiographically detectable metastasis. The sensitivity, specificity, PPV, and NPV were calculated to be 64.7%, 100.0%, 100.0%, and 80.6% respectively. Out of 6 patients who underwent had ctDNA testing on SAbR, 5 had undetectable levels and the only patient that had detectable ctDNA levels showed a robust decline in ctDNA levels post SAbR. In the interleukin-2 treated patient, detectable levels of ctDNA became undetectable post treatment which also correlated with a complete radiographic response. Conclusions: This study highlights the utility of ctDNA as a prognostic biomarker in the surveillance of oRCC patients who were previously treated with SAbR. A high SPE and PPV suggests that rising ctDNA levels may harbinger radiographic progression requiring systemic therapy intervention. A larger study is warranted to further validate the findings of this study and to optimally integrate ctDNA kinetics to direct subsequent treatment choices for the oRCC patients.

A phase 1 study of triple-targeted therapy with BRAF, MEK, and AKT inhibitors for patients with BRAF-mutated cancers.

Aberrant PI3K/AKT signaling in BRAF-mutant cancers contributes to resistance to BRAF inhibitors. The authors examined dual MAPK and PI3K pathway inhibition in patients who had BRAF-mutated solid tumors (ClinicalTrials.gov identifier NCT01902173). Patients with BRAF V600E/V600K-mutant solid tumors received oral dabrafenib at 150mg twice daily with dose escalation of oral uprosertib starting at 50mg daily, or, in the triplet cohorts, with dose escalation of both oral trametinib starting at 1.5mg daily and oral uprosertib starting at 25mg daily. Dose-limiting toxicities (DLTs) were assessed within the first 56days of treatment. Radiographic responses were assessed at 8-week intervals. Twenty-seven patients (22 evaluable) were enrolled in parallel doublet and triplet cohorts. No DLTs were observed in the doublet cohorts (N=7). One patient had a DLT at the maximum administered dose of triplet therapy (dabrafenib 150mg twice daily and trametinib 2mg daily plus uprosertib 75mg daily). Three patients in the doublet cohorts had partial responses (including one who had BRAF inhibitor-resistant melanoma). Two patients in the triplet cohorts had a partial response, and one patient had an unconfirmed partial response. Pharmacokinetic data suggested reduced dabrafenib and dabrafenib metabolite exposure in patients who were also exposed to both trametinib and uprosertib, but not in whose who were exposed to uprosertib without trametinib. Concomitant inhibition of both the MAPK and PI3K-AKT pathways for the treatment of BRAF-mutated cancers was well tolerated, leading to objective responses, but higher level drug-drug interactions affected exposure to dabrafenib and its metabolites.

Feasibility of Monitoring Response to Metastatic Prostate Cancer Treatment with a Methylation-Based Circulating Tumor DNA Approach

Background: Metastatic prostate cancer (mPCA) poses challenges in treatment response assessment, particularly in cases where prostate-specific antigen (PSA) levels do not reliably indicate a response. Liquid biopsy, focusing on circulating cell-free DNA (ccfDNA) methylation analysis as a proxy for circulating tumor DNA, offers a non-invasive and cost-effective approach. This study explores the potential of two methylation markers, short stature homeobox 2 (SHOX2) and Septin 9 (SEPT9), as on-mPCA-treatment biomarkers. Methods: Plasma samples were collected from 11 mPCA patients undergoing various treatments. Quantitative assessment of hypermethylated SHOX2 (mSHOX2) and SEPT9 (mSEPT9) levels in ccfDNA was conducted through methylation-specific real-time PCR. Early and overall dynamics of PSA, mSHOX2, and mSEPT9 were analyzed. Statistical evaluation employed Wilcoxon tests. Results: mSHOX2 demonstrated a significant decline post-treatment in patients with a radiographic treatment response as well as in an early treatment setting. mSEPT9 and PSA exhibited non-significant declines. In individual cases, biomarker dynamics revealed unique patterns compared to PSA. Discussion: mSHOX2 and mSEPT9 exhibit dynamics on mPCA treatment. This proof-of-concept study lays the groundwork for further investigation into these markers as valuable additions to treatment response monitoring in mPCA. Further validation in larger cohorts is essential for establishing clinical utility.

Des-gamma-carboxy prothrombin (DCP) as a biomarker for treatment response in hepatocellular carcinoma.

547 Background: Causes of variable disease response to first-line treatment with atezolizumab/bevacizumab (atezo/bev) in hepatocellular carcinoma (HCC) patients remain unclear. Identifying tumor markers that predict treatment efficacy may help raise clinical suspicion for early disease progression. The role of des-gamma-carboxy prothrombin (DCP) is not well established in Hepatitis B Virus (HBV) non-endemic areas. This study aimed to investigate DCP as a predictive biomarker of atezo/bev treatment response in HCC patients. Methods: This single-center retrospective analysis evaluated DCP and radiographic response in HCC patients who received atezo/bev in the first-line setting. DCP was measured at the time of best response evaluation and compared to day one of atezo/bev initiation. Elevated DCP was defined by >=7.5 ng/mL. DCP response was defined as a decrease of >=50% at response assessment compared with baseline. Treatment response was evaluated based on imaging modalities including computed tomography and/or magnetic resonance imaging. Objective response rate (ORR) was defined as the percentage of patients with complete response (CR) and partial response (PR). Disease control rate (DCR) was defined as the percentage of patients with CR, PR, and stable disease (SD). No Response (NR) was defined as the percentage of patients with SD and PD. Comparisons of treatment effects were performed using two-tailed Fisher Exact Probability Test. Results: A total of 53 HCC patients treated with atezo/bev as first-line therapy were included. The best treatment responses according to radiographic evaluation were as follows: CR 3.8%, PR 22.6%, SD 52.8%, and PD 20.8%, respectively. Patients with DCP response had ORR of 69% (odds ratio, 15.75; 95% CI, 3.50-70.9; P=.0002) and DCR of 100% ( P=.047). Patients with >=50% increase in DCP at response evaluation compared to day one of treatment had ORR of 4.5% and NR of 95% ( P=.0035). On day one of treatment, 70% of patients had an elevated DCP. There was no difference between elevated DCP vs non-elevated DCP on day one of treatment and ORR. Conclusions: This study found that DCP has utility in predicting response to atezo/bev for HCC patients in HBV non-endemic areas. Further studies are needed to confirm findings and evaluate the prognostic implications of DCP in HBV non-endemic areas.

Immune checkpoint blockade combined with targeted therapies to provide disease control in mismatch repair-proficient colorectal cancer with peritoneal metastases.

133 Background: Metastatic colorectal adenocarcinoma (mCRC) with proficient mismatch repair (pMMR) is associated with poor response to cytotoxic chemotherapy in the refractory setting, with a median overall survival (OS) of 10.8 months. Recent immunotherapy (IO) regimens utilizing a combination of immune checkpoint blockade (ICB) and tyrosine kinase inhibitors (TKIs) that suppress tumor-associated macrophages (TAMs) have shown promise for extra-hepatic, but not hepatic metastases. However, few studies include patients with peritoneal metastases (PMs) and the response rate of PMs to these therapies is unknown. We sought to examine the disease control rates (DCR) and OS of patients treated with PM who were treated with ICB regimens. Methods: Patients with pMMR tumors treated with ICB and TKI after progression on 1st and 2nd-line therapy from 2015 to 2022 were identified. Date of start of therapy, end of therapy, last follow up and vital status were determined from the medical record. Radiographic disease response within each metastasis site at 6 months and at last follow-up on therapy was determined for each patient. Overall survival was estimated using the Kaplan-Meier method. Results: A total of 93 patients treated with an ICB and TKI after at least two lines of cytotoxic systemic therapy were identified. Five were excluded due to dMMR/MSI-H status and eight due to lack of follow-up. A total of 33 patients with PM, with or without other metastases, had a median follow-up on therapy of 6.1 months and median follow-up until death or censoring of 9.8 months. Median OS was 15.1 (9.7-29.5) months, and 18-month survival was 43% (95%CI: 24-62%). OS was not associated with either BRAF (HR 0.98, 0.38-2.6, p=0.98) or RAS (HR 1.50, 0.62- 3.63, p=0.37) mutation status. Partial response of PM was noted in 5 patients (15%), stable disease in 14 (42%) and progressive disease in 14 (42%), resulting in DCR of 57%. Disease control for all metastatic sites was noted in 9 (27%) of patients, and median OS was not reached at 2 years. Median OS for patients without peritoneal progression was 22.0 months [12.3-NR], and PM progression was associated with worse OS (HR 0.66, p=0.024). A total of 32 patients with any metastatic site were treated for at least 6 months. Median follow-up was 16.1 months for this cohort. DCR at 6 months for CRLM was 23% (3/13), PM was 58% (14/24, p=0.08 vs CRLM) and for LM was 62% (8/13, p=0.11 vs CRLM). Conclusions: Response to ICB and targeted therapy combinations can vary widely by metastatic site, with liver trending towards less response than peritoneum or lung. Disease control in the peritoneum can be achieved in the majority of patients, and median OS compares favorably to standard-of-care therapy in the refractory setting. Patients with peritoneal disease should be included in future trials of ICBs as treatment options are otherwise limited.

Non-responders to neoadjuvant chemotherapy in pancreatic adenocarcinoma: Characteristics and outcomes.

662 Background: For patients with localized pancreatic adenocarcinoma, resection and systemic therapy remain the mainstays of curative-intent treatment. Neoadjuvant chemotherapy has been frequently employed with the goals of addressing systemic disease early and improving patient selection for surgery. Those who do not respond to neoadjuvant therapy present a challenge with a lack of randomized data to aid in decision making. Here we sought to define the characteristics and outcomes of those patients to guide clinical practice. Methods: This was a single-institution retrospective cohort study using a prospectively maintained database of those diagnosed with pancreatic adenocarcinoma. Patients included in the study were those who received neoadjuvant chemotherapy. Non-responders were defined as those with both no radiographic and no biochemical response at the first re-assessment after initiation of therapy. Results: A total of 176 patients were identified who were treated with neoadjuvant chemotherapy with curative intent. Of those, 42 (23.8%) patients had no evidence of either radiographic or biochemical response. Of those patients, 14 were upfront resectable (33.3%) and 20 were borderline resectable (47.6%). An additional 8 (19%) were locally advanced. Most patients received FOLFIRINOX as a first line chemotherapy agent (n = 25, 59.5%). A total of 12 (28.6%) patients underwent neoadjuvant radiation therapy. A total of 19 (45.2%) proceeded to surgery and two of those were found to be unresectable at exploration, resulting in 17 (40.5%) who ultimately received curative-intent resection. Exactly half (n = 21) of the patients had their chemotherapy switched (CS). Of those who had CS, 11 (52.4%) had evidence of local tumor progression on their initial restaging scan compared to just 3 (14.3%) of those who did not (p = 0.02). Additionally, patients who had CS had higher incidence of vascular involvement on their initial scan (90.5% vs 52.3%, p = 0.051). A total of 6 (28.6%) who underwent CS had subsequent biochemical response compared 4 (19.0%) of those who did not. Ultimately, 6 (28.6%) of those who had CS ultimately proceeded to surgery compared to 13 (61.9%) of those who did not (p = 0.062). Interestingly, there was no significant difference in median overall survival between those who had CS (18.6 months) and those who did not (19.9 months, p = 0.525). Conclusions: Non-responders to frontline neoadjuvant systemic therapy present a clinical challenge and have poor rates of curative-intent resection. Chemotherapy switch was employed mostly in cases with worse prognostic factors and thus infrequently lead to resection. Despite this, patients who underwent CS had similar overall survival to those who did not. These data suggest there may be a role for chemotherapy switch in those who do not respond to front line chemotherapy.

Results of a phase II, open-label pilot study evaluating the safety and activity of liposomal irinotecan (Nal-IRI) in combination with 5-FU and oxaliplatin (NALIRIFOX) in preoperative treatment of pancreatic adenocarcinoma (NEO-Nal-IRI study).

655 Background: Neoadjuvant treatment for resectable pancreatic cancer (PDAC) is increasing in acceptability, but a standard regimen has yet to be established. The modified FOLFIRINOX (5-fluorouracil, leucovorin, oxaliplatin and irinotecan) regimen often requires dose modifications, delays and growth factor support due to toxicity. Liposomal irinotecan injection (Nal-IRI) is FDA-approved with a well-tolerated safety profile in relapsed, refractory mPDAC. This current study substitutes Nal-IRI for traditional irinotecan in the mFOLFIRINOX regimen (NALIRIFOX) and aims to demonstrate safe neoadjuvant delivery. NALIRIFOX is currently under review by the FDA for frontline mPDAC. Methods: This phase 2, open-label, multicenter single-arm study enrolled adult patients (pts) with operable PDAC, resectability (borderline vs. resectable) confirmed by multiD conference, adequate organ function, and ECOG performance status (0-1). Pts received NALIRIFOX (per NAPOLI-3) every 2 wks x 4 mo followed by repeat imaging and surgical resection 4-8 wks later. Primary endpoint is the composite 30 day post-op major complication rate (hospital re-admission, death, second surgery, procedure or major complication extending hospital stay). A sample size of 25 pts will detect a 20% reduction in 1° endpoint (from 30% to 10%; 1-sided exact test; α=0.05; β=.8). Toxicity, treatment completion, R0 resection, clinical, biochemical and radiographic response rates and QOL during treatment (FACT-G) are 2° endpoints. Serial microbiota specimens have been collected for exploratory analysis. Results: From May 2019 to Feb 2023, 45 pts were enrolled from 4 centers. Median age was 63 (41-76), majority women (53%), white (89%) with borderline (n=30) or resectable (n=15) disease. All 45 pts initiated treatment with 34 proceeding to surgery and 29 completing definitive resection. Most common grade >3 AEs included non-febrile neutropenia (41%), diarrhea (30%), and anorexia (22%). Those not obtaining definitive resection had progressive disease (radiographic n=6; intra-op n=5), physician change of tx (n=2), toxicity (n=2; CMV colitis and TPN requirement/sepsis) or consent withdraw (n=1). Three (10%) pts had a post-op major complication (p=0.012). One pt died from post-op bleeding complications. Resections included both borderline (n=15) and resectable (n=14) initial disease with overall R0 resection rate of 89%. Conclusions: Neoadjuvant NALIRIFOX was safe, having met the primary study objective, with reasonable rates of treatment completion and surgical outcomes for this relatively high-risk group of pts. Additional analyses are ongoing and will be reported at the meeting. Clinical trial information: NCT03483038 .

A phase II trial of induction systemic mFOLFIRINOX followed by hepatic arterial infusion of floxuridine and dexamethasone given concurrently with systemic mFOLFIRI as a first-line therapy in patients with unresectable liver-dominant intrahepatic cholangiocarcinoma (HELIX-1).

511 Background: Most patients with intrahepatic cholangiocarcinoma (ICC) have unresectable or multifocal liver-dominant disease. Survival after first-line systemic therapy remains poor, with median progression-free (mPFS) and overall survival of 7.2 and 12.8 months, respectively. Hepatic arterial infusion (HAI) therapy with floxuridine maximizes liver-specific treatment with minimal systemic toxicity and potentially offers improved disease control when combined with systemic therapy. Methods: HELIX-1 (NCT04251715) is an investigator-initiated, first-line, single-center, single-arm phase II clinical trial for patients with liver-dominant unresectable or multifocal ICC. The trial was designed with a patient safety run-in evaluating toxicity from the combined therapy. Pre-trial screening included laparoscopy, biopsies, and PET/CT. Eligible patients were treated with systemic mFOLFIRINOX for 4 cycles in order to select those likely to benefit from HAI. Patients with disease control on restaging proceeded to HAI pump placement and treatment with HAI floxuridine for 14 days followed by systemic mFOLFIRI on a 28-day cycle. The co-primary objectives were to assess safety of the combined therapeutic strategy and the disease control rate (DCR) at 6 months (RECIST v1.1) at end of trial (EOT). Results: A total of n=5 patients with liver-only ICC enrolled in the trial and completed the entire study protocol. The median age was 60 years (range 42-69) with a dominant lesion size of 9.8cm (range 8.4-14.5). All patients had both right and left hemiliver involvement with a median of 9 intrahepatic tumors (range 1-15). No patients experienced grade 3 or 4 adverse events, or hepatic dysfunction leading to cessation of HAI therapy. The DCR at 6 months was 100%, with a mPFS of 18.2 months. All five patients achieved partial radiographic response (PR) while receiving HAI therapy, and remain alive with liver-only disease at a median of 18.4 months (range 12.7-20) after study enrollment. After continuing treatment with HAI and systemic mFOLFIRI beyond the EOT, two patients transitioned to HAI treatment only and then to biochemical and radiographic surveillance without therapy after demonstrating PR and CA19-9 normalization. Conclusions: Integration of HAI floxuridine with mFOLFIRI following mFOLFIRINOX induction for patients with liver-only advanced ICC is well-tolerated and demonstrates longer DCR in comparison to historical controls. The combined regimen minimized systemic toxicity and allowed a large proportion of patients to transition to liver-only HAI treatment with maintained disease control. Future directions include combining HAI with new first-line systemic regimens for patients with advanced ICC. Clinical trial information: NCT04251715 .

Radiographic and serologic response in patients with unresectable hepatocellular carcinoma receiving systemic antineoplastic treatments: A trial-level analysis.

In a disease like unresectable hepatocellular carcinoma, overall survival is an inadequate outcome measure for evaluating the effectiveness of treatments given the high risk of death from liver failure. There is an unmet need for reliable alternative end points for clinical trials and daily clinical practice. To evaluate treatment response in patients with unresectable or metastatic hepatocellular carcinoma (mHCC), imaging-related end points are often used, whereas serologic end points have been developed for patients with serum alpha-fetoprotein levels >20ng/mL. The objective of this study was to evaluate clinical trials that report concomitant assessment of radiographic and serologic response in patients with mHCC. After a systematic review, studies that evaluated response according to radiographic and serologic criteria were selected. A correlation between progression-free survival (PFS) and overall survival (OS) was performed, and a linear regression of each response-related outcome measure with OS was reported. Finally, the effect of eight baseline variables on OS and response-related measures was evaluated. Twenty-six studies were included, including 16 first-line studies and 10 second-line studies. PFS and response rates demonstrated a significant relationship with OS, whereas disease control rates did not. The responses were correlated with OS, particularly in the first-line setting, after targeted therapy, and whenever assessment was early. Among the baseline variables, only performance status had a prognostic role, whereas hepatitis B virus-related liver disease was associated with higher radiographic response rates. PFS and radiographic and serologic response rates appear to be reliable intermediate end points in patients with mHCC who are undergoing systemic antineoplastic therapy. However, the serologic response is available earlier.

Abstract B002: Phase I study of endoscopic ultrasound (EUS)-guided NBTXR3 delivery activated by radiotherapy (RT) for locally advanced or borderline resectable pancreatic cancer (LAPC or BRPC)

Abstract Patients with LAPC or BRPC often receive radiation therapy (RT) after chemotherapy (chemo) if no metastatic progression has occurred. Historically, CA19-9 normalizes in ~20 to 30% of patients after all therapy. While escalated dose radiotherapy (EDR) has shown promising survival in selected patients, extending use of EDR to all patients is challenging due to RT dose limitations of the bowel. To overcome this limitation, we are investigating NBTXR3, composed of functionalized hafnium oxide nanoparticles administered by a single intratumoral injection, locally amplifying the RT dose. In this phase 1 trial, the primary objective is to determine the NBTXR3 recommended phase 2 dose (RP2D). Secondary objectives are to measure anti-tumor effects. The study uses a Bayesian optimal interval design (BOIN) and has two parts: dose-finding (NBTXR3 at [level 1] 33% of gross tumor volume [GTV] or [level 2] at 42% of GTV) and cohort expansion at RP2D. In part 1, eligibility criteria included only LAPC patients with no evidence of metastatic disease after 2-6 months of chemo, part 2 allows BRPC. NBTXR3 was administered once prior to RT via an EUS-guided intratumoral injection. All patients received 45 Gy in 15 fractions with intensity modulated radiation therapy (IMRT). Patients were followed up to 1 year. Dose-limiting toxicities (DLTs) were defined as any grade ≥ 3 adverse events definitely or possibly related to NBTXR3 and/or RT. Target tumor response was per RECIST v1.1 criteria. CA19-9 was measured serially. We defined CA19-9 normalization as a value of 37 U/ml after finishing NBTXR3/RT. We compared rates of CA19-9 normalization in this phase 1 trial to a historical cohort of patients who received modern chemo/RT without NBTXR3. As of July 12, 2023, 15 LAPC patients have been treated with NBTXR3/RT. The median age was 63 years [range 43-81], 8 males, 7 females. The first patient (level 1) and subsequent 14 patients (level 2) had no injection complications. Level 2 had 1 non-serious DLT related to RT. At 4 weeks post RT, 13 had stable disease (SD) locally (2 had progressive disease [PD] overall), 1 had PD locally, and 1 had radiographic complete response (CR). At 3 months post RT, 11 had SD locally (1 PD overall), 1 PD locally, and 1 had surgery with negative margins and no residual viable tumor. 9 patients had elevated CA19-9 before NBTXR3/RT, 7 of these 9 (78%) had a decrease in CA19-9 subsequently, and 2 of these 9 (22%) had CA19-9 normalization eventually. 12 patients had elevated CA19-9 at diagnosis, and 5 out of 12 patients (42%) had normalization of CA19-9 after all therapy. We reviewed 455 patients with LAPC/BRPC between 2015-2019 who were treated at our institution as a comparison cohort for CA19-9 normalization rates. Out of 307 patients with elevated CA19-9 at diagnosis and normal bilirubin, 95 normalized (31%) and 212 did not normalize (69%) within 6 months of receiving cytotoxic therapy. The RP2D of NBTXR3 is 42% of GTV. The responses and CA19-9 results in comparison to historical data suggest promising anti-tumor efficacy of NBTXR3/RT. Citation Format: Gabriela Fuentes, Maria J. Rodriguez, Matthew H.G. Katz, Naruhiko Ikoma, Ching-Wei D. Tzeng, Michael Overman, Shubham Pant, Michael S. Lee, Robert A. Wolff, Milind Javle, Cullen M. Taniguchi, Emma B. Holliday, Ethan B. Ludmir, Prajnan Das, Albert C. Koong, Omar I. Vivar, Suyu Liu, Eric P. Tamm, Leonard A. Farber, Manoop S. Bhutani, Eugene J. Koay. Phase I study of endoscopic ultrasound (EUS)-guided NBTXR3 delivery activated by radiotherapy (RT) for locally advanced or borderline resectable pancreatic cancer (LAPC or BRPC) [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Pancreatic Cancer; 2023 Sep 27-30; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(2 Suppl):Abstract nr B002.

Circulating Tumor DNA to Predict Radiographic and Pathologic Response to Total Neoadjuvant Therapy in Locally Advanced Rectal Cancer.

Despite advances in treatment and response assessment in locally advanced rectal cancer (LARC), it is unclear which patients should undergo nonoperative management (NOM). We performed a single-center, retrospective study to evaluate post-total neoadjuvant therapy (TNT) circulating tumor DNA (ctDNA) in predicting treatment response. We found that post-TNT ctDNA had a sensitivity of 23% and specificity of 100% for predicting residual disease upon resection, with a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 47%. For predicting poor tumor regression on MRI, ctDNA had a sensitivity of 16% and specificity of 96%, with a PPV of 75% and NPV of 60%. A commercially available ctDNA assay was insufficient to predict residual disease after TNT and should not be used alone to select patients for NOM in LARC.

VB-111 (ofranergene obadenovec) in combination with nivolumab in patients with microsatellite stable colorectal liver metastases: a single center, single arm, phase II trial

BackgroundMicrosatellite stable colorectal liver metastases (MSS CLM) maintain an immunosuppressive tumor microenvironment (TME). Historically, immune-based approaches have been ineffective. VB-111 (ofranergene obadenovec) is a genetically-modified adenoviral vector targeting the TME;...

Real world evidence of enfortumab vedotin in patients with advanced urothelial cancer: A multicenter observational study.

To explore the characteristics of patients and assess the effectiveness of enfortumab vedotin (EV) in those with treatment-resistant advanced urothelial cancer in a real-world setting. A multicenter observational study was conducted on 103 evaluable patients with advanced urothelial cancer who received EV. Outcomes were assessed by radiographic response, progression-free survival (PFS), and overall survival (OS), with treatment-related adverse events (trAEs). Radiographic response was assessed using Response Evaluation Criteria in Solid Tumors version 1.1, while trAEs were studied in line with Common Terminology Criteria for Adverse Events version 5.0. The median follow-up was 8.9 months (range, 0.1-16.4). The observed objective response rate was 50.5%. The median PFS was 6.0 months (95% CI: 4.7-9.8), and the median OS was 14.5 months (95% CI: 12.4-not reached). Out of the 103 patients, 19 (18.4%) had an Eastern Cooperative Oncology Group performance status of 2 or more, 14 (14.7%) had an non-urothelial carcinoma histology, and 40 (38.3%) had at least one pre-existing comorbidity. There were 26 (25.2%) patients who reported 49 trAEs, with 9 (18.3%) being grade 3 or higher. The most common trAEs included rash, occurring in 18.4%. This study describes the characteristics and outcomes of patients with previously treated advanced urothelial cancer receiving EV. The findings demonstrate that EV showed robust anti-tumor activity and had manageable safety profiles outside the clinical trial setting.

Druggable genomic landscapes of high-grade gliomas.

Despite the putatively targetable genomic landscape of high-grade gliomas, the long-term survival benefit of genomically-tailored targeted therapies remains discouraging. Using glioblastoma (GBM) as a representative example of high-grade gliomas, we evaluated the clonal architecture and distribution of hotspot mutations in 388 GBMs from the Cancer Genome Atlas (TCGA). Mutations were matched with 54 targeted therapies, followed by a comprehensive evaluation of drug biochemical properties in reference to the drug's clinical efficacy in high-grade gliomas. We then assessed clinical outcomes of a cohort of patients with high-grade gliomas with targetable mutations reviewed at the Johns Hopkins Molecular Tumor Board (JH MTB; n = 50). Among 1,156 sequence alterations evaluated, 28.6% represented hotspots. While the frequency of hotspot mutations in GBM was comparable to cancer types with actionable hotspot alterations, GBMs harbored a higher fraction of subclonal mutations that affected hotspots (7.0%), compared to breast cancer (4.9%), lung cancer (4.4%), and melanoma (1.4%). In investigating the biochemical features of targeted therapies paired with recurring alterations, we identified a trend toward higher lipid solubility and lower IC50 in GBM cell lines among drugs with clinical efficacy. The drugs' half-life, molecular weight, surface area and binding to efflux transporters were not associated with clinical efficacy. Among the JH MTB cohort of patients with IDH1 wild-type high-grade gliomas who received targeted therapies, trametinib monotherapy or in combination with dabrafenib conferred radiographic partial response in 75% of patients harboring BRAF or NF1 actionable mutations. Cabozantinib conferred radiographic partial response in two patients harboring a MET and a PDGFRA/KDR amplification. Patients with IDH1 wild-type gliomas that harbored actionable alterations who received genotype-matched targeted therapy had longer progression-free (PFS) and overall survival (OS; 7.37 and 14.72 respectively) than patients whose actionable alterations were not targeted (2.83 and 4.2 months respectively). While multiple host, tumor and drug-related features may limit the delivery and efficacy of targeted therapies for patients with high-grade gliomas, genotype-matched targeted therapies confer favorable clinical outcomes. Further studies are needed to generate more data on the impact of biochemical features of targeted therapies on their clinical efficacy for high-grade gliomas.

Granulocyte transfusions in severe aplastic anemia.

Patients with severe aplastic anemia (SAA) are at high risk of morbidity and mortality due to severe infections. We aimed to characterize the role of granulocyte transfusions (GT) in SAA. Primary outcomes were survival after the first GT, including overall survival (OS) at last follow up, survival to discharge, and receipt of a hematopoietic stem cell transplant (HSCT) Secondary outcomes included evaluation of clinical response at 7 and 30 days after initiation of GT, using a clinical scoring system incorporating microbiological and radiographic response. Twenty-eight SAA patients underwent 30 GT courses with a per-dose median of 1.28x109 granulocytes/kilogram (range, 0.45-4.52x109). OS from initial GT to median last follow up (551 days) was 50%, with 39% (11/28) alive at last follow up. Sixty-four percent (18/28) of all patients survived to hospital discharge. Patients with a complete or partial response, or stable infection, at 30 days had significantly better OS compared to non-responders (P=0.0004). Eighty-six percent (18/21) of patients awaiting HSCT during GT underwent a transplant and 62% (13/21) survived to post-HSCT discharge. Sex, type of infection, and percentage of days with absolute neutrophil count >0.2x109/L during the course of GT were not predictive of survival (P=0.52, P=0.7 and P=0.28, respectively). Nine of 28 (32%) patients developed new or increased human leukocyte antigen alloimmunization during their GT course. GT in SAA may have an impact on survival in those patients with improvement or stabilization of their underlying infection. Alloimmunization can occur and OS in this population remains poor, but GT may be a useful tool to bridge patients to curative treatment with HSCT.

Long-term Survival Among Patients With De Novo Human Epidermal Growth Receptor 2-Positive Metastatic Breast Cancer in Manitoba.

Although metastatic breast cancer (MBC) is considered incurable, human epidermal growth receptor 2 (HER2)-directed therapy has improved outcomes significantly, with some patients experiencing durable responses to treatment. The aim of this study was to identify potential predictors of long-term survival (LTS) among patients with de novo HER2-positive MBC who received HER2-directed treatment. Eligible patients from 2008 to 2018 were identified using the Manitoba Cancer Registry. LTS was defined as survival ≥5 years from the time of diagnosis. Univariate logistic regression models were performed to assess variables of clinical interest and the odds of LTS. Overall survival (OS) was defined as the time from diagnosis of MBC to death of any cause. OS was estimated using the Kaplan-Meier method with log-rank comparative analyses as a univariate analysis. A Cox proportional hazards model was used for OS estimates in a univariate analysis. A total of 62 patients were diagnosed with de novo HER2-positive MBC and received HER2-directed therapy. Eighteen (29%) achieved LTS. The median OS of the whole cohort was 50.2 months (95% CI: 28.6-not reached). Radiographic response to first-line treatment was associated with LTS; complete and partial responses were both associated with higher odds of LTS (odds ratio: 28.33 [95% CI: 2.47-4006.71, P = 0.0043] and odds ratio: 7.80 [95% CI: 0.7317-1072.00, P = 0.0972], respectively). The best radiographic response was associated with improved OS. Radiographic response to first-line HER2-directed therapy is a predictor for LTS in patients with de novo HER2-positive MBC. Larger studies are needed to identify patients who can safely discontinue HER2-targeted therapy.

Promising Therapeutic Activity of 177 Lu-PSMA-617 in Synchronous High-Volume Metastatic Hormone-Sensitive Prostate Cancer : A Pilot Experience.

177 Lu-PSMA-617 has been shown to improve survival outcomes in patients with end-stage metastatic castration-resistant prostate cancer. However, data in earlier lines remain limited. In this study, we intended to evaluate the efficacy and safety of 177 Lu-PSMA-617 in patients with synchronous high-volume metastatic hormone-sensitive prostate cancer (mHSPC). Hormone-sensitive prostate cancer patients with synchronous high-volume metastases (defined as ≥4 skeletal metastases with ≥1 extra-axial site or any visceral metastasis) showing high PSMA expression on 68 Ga-PSMA-11 PET/CT and ineligible/unwilling for conventional chemohormonal treatment options were selected. Approximately, ~5.55-7.4 GBq of 177 Lu-PSMA-617 was administered intravenously at 8-12 weeks intervals, up to 6 cycles. All patients underwent concomitant androgen deprivation therapy/orchiectomy. The outcome measures included the proportion of patients achieving an undetectable serum prostate-specific antigen (PSA) (ie, ≤0.2 ng/mL) at any time point after therapy, best PSA response rate, objective radiographic response rate, radiographic progression-free survival, overall survival, and adverse events. Ten patients with high-volume mHSPC received a median cumulative activity of 32.4 GBq (range, 7.4-44.4) of 177 Lu-PSMA-617 over 1-6 cycles. Five patients (50%) achieved an undetectable PSA with 9 patients (90%) showing a ≥50% decline in PSA from baseline. Nine patients underwent radiological follow-up, of which 7 (77.8%) had an objective response. The median radiographic progression-free survival was 24 months (95% confidence interval, 18-30), whereas the median overall survival was not reached. None of the patients had any grade 3/4 adverse event. 177 Lu-PSMA-617 seems to be a promising efficacious and safe treatment option for patients with synchronous high-volume mHSPC.