Early Tumor Shrinkage Research Articles

313. CLINICAL EVALUATION OF PEMBROLIZUMAB PLUS CISPLATIN AND FLUOROURACIL AS INDUCTION FOR PATIENTS WITH CT4B ESOPHAGEAL SQUAMOUS CELL CARCINOMA

Abstract Background Definitive chemoradiotherapy (dCRT) is a standard treatment for patients with cT4b esophageal squamous cell cancer (ESCC). In these 3 decades, radiation technique has been improved, and chemotherapy with cisplatin, fluorouracil, and/or taxans was combined before and after dCRT. However, its CR rate remains around 25% and its 3-year survival rate also remains below 30%. Although conversion surgery has been applied to improve the survival of these patients, no study has shown significant superiority to CR after dCRT in survival to date. Chemotherapy of pembrolizumab plus cisplatin and fluorouracil was applied to patients with unresectable or recurred esophageal cancer and demonstrated significant survival benefit and good objective response. We provided this therapy as induction to improve the therapeutic result of patients with cT4b ESCC. Method From April 2022 to August 2023, 11 untreated patients with cT4b ESCC had this chemotherapy as induction, with pembrolizumab 200 mg plus chemotherapy (5-fluorouracil 800 mg/m2 on days 1-5 plus cisplatin 80 mg/m2 on day 1) once every 3 weeks. Patients with cervical lymph node metastasis were included. After 2 or 3 cycles, the therapeutic effect was evaluated according to RECIST. Adverse events were evaluated according to CTCAE. Result Average age was 70, and 3 patients had cervical lymph node metastasis. Objective response rate was 82% (CR 1, PR 8). In these 9 patients, the volume of tumors shrank by more than 60% within 11 weeks. Over Grade 3 neutropenia developed in 2 (18%), but no G-CSF was administered. Gastric ulcer perforation developed in 1 (9%). In 2 patients, the dose of cisplatin should be modified due to renal damage. One patient had prolonged renal damage and had conversion surgery after 1 cycle. Eight patients had dCRT. One of 8 terminated dCRT due to another disease. Two of 8 just finished dCRT, and one is under dCRT. Of 3 were evaluated as CR, and followed without any treatment. Local and lymphatic recurrence developed in one PR patient. To date, no specific adverse events relating to pembrolizumab developed during and after dCRT. Of the 2 had conversion surgery without any severe post-operative complications. Discussion and Conclusion In our preliminary study, chemotherapy of pembrolizumab plus cisplatin and fluorouracil showed good objective response (82%) and early tumor shrinkage (more than 60% within 11 weeks). Over grade 3 hematological adverse events developed in only 18% of patients. These results suggest this regimen could be administered to patients with cT4b ESCC as induction especially followed by dCRT. This regimen can reduce tumor volume and control lymphatic spread, and these factors seem to improve prognosis and prevent fatal complications such as fistula or stricture of patients with cT4b ESCC who have dCRT. We plan a clinical trial of this chemotherapy followed by dCRT for patients with cT4b ESCC.

Utility of Assessing Early Tumor Shrinkage as an Efficacy Predictor in Patients with Non-Surgically Indicated or Recurrent Esophageal Cancer Treated with Nivolumab plus Ipilimumab.

Nivolumab plus ipilimumab combination therapy has been administered as a first-line treatment in Japan since 2022 for patients with unresectable progressive or recurrent esophageal cancer. The efficacy and safety of this immune checkpoint inhibitor (ICI) doublet therapy are now being evaluated, and it is necessary to identify populations that benefit from this treatment at an early phase after initiation. For patients not showing early benefit, changing as soon as possible to other therapeutic strategies could improve their survival outcomes. Therefore, we attempted to identify decision-making factors such as early tumor shrinkage (ETS) based on treatment experience with ICI doublet therapy. The study included 19 patients who received nivolumab plus ipilimumab for non-surgically indicated or recurrent esophageal cancer between July 2022 and November 2023. Tumors were assessed approximately every 2 months after treatment initiation. The effects of ETS, depth of response (DpR), and clinicopathologic features, including immune-related adverse events (irAEs), on progression-free and overall survival were evaluated using Kaplan-Meier plots and Cox proportional hazard models. The mean duration of ICI doublet administration was 5.89 months (range, 1-16 months). At first evaluation, patients who exhibited no tumor progression >20% indicated possible response to ICI doublet therapy, and patients whose tumors shrank even minimally exhibited favorable progression-free survival. Higher DpR at any cut-off line exhibited better progression-free survival than those with lower DpR. Fifteen patients experienced irAEs, with 13 of these patients experiencing irAEs within 3 months of treatment initiation. irAEs were associated with the efficacy of ICI doublet therapy, but efficacy could not be predicted based on early irAE experience. ETS-high, DpR-high, and irAEs might be associated with favorable responses to nivolumab plus ipilimumab. As a predictor of efficacy at an early phase, ETS >0% could be a deciding factor for continuing ICI doublet therapy.

Model-informed Evidence for Clinical Non-inferiority of Every-2-Weeks Versus Standard Weekly Dosing Schedule of Cetuximab in Metastatic Colorectal Cancer.

Cetuximab was initially developed and approved as a first-line treatment in patients with unresectable metastatic colorectal cancer (mCRC) for weekly administration (250 mg/m2 Q1W with 400 mg/m2 loading dose). An every-2-weeks schedule (500 mg/m2 Q2W) was approved recently by several health authorities. Being synchronized with chemotherapy, Q2W administration should improve patients' convenience and healthcare resource utilization. Herein, we present evidence of non-inferiority of Q2W cetuximab, compared with Q1W dosing using pharmacometrics modeling and clinical trial simulation (CTS). Pooled data from five phase I-III clinical trials in 852 patients with KRAS wild-type mCRC treated with Q1W or Q2W cetuximab were modeled using a population exposure-tumor size (TS) model linked to overall survival (OS); exposure was derived from a previously established population pharmacokinetic model. A semi-mechanistic TS model adapted from the Claret model incorporated killing rate proportional to cetuximab area under the concentration-time curve over 2 weeks (AUC) with Eastern Cooperative Oncology Group (ECOG) status as covariate on baseline TS. The OS was modeled with Weibull hazard using ECOG, baseline TS, primary tumor location, and predicted percent change in TS at 8 weeks as covariates. Model-based simulations revealed indistinguishable early tumor shrinkage and survival between Q2W vs. Q1W cetuximab. CTS evaluated OS non-inferiority (predefined margin of 1.25) in 1,000 trials, each with 2,000 virtual patients receiving Q2W or Q1W cetuximab (1:1), and demonstrated non-inferiority in 94% of cases. Taken together, these analyses provide model-based evidence for clinical non-inferiority of Q2W vs. Q1W cetuximab in mCRC with potential benefits to patients and healthcare providers.

Biomarker-stratified first-line treatment of right-sided metastatic colon cancer with interdisciplinary collaboration in the IVOPAK II trial.

Patients with right-sided metastatic colon carcinoma have a significantly worse prognosis than those with left-sided colorectal cancer (CRC), regardless of treatment. The aim of the prospective IVOPAK II study was to implement an interdisciplinary guideline-conform personalized CRC palliative therapy of metastatic colorectal carcinoma and to improve the overall survival (OS) by multidisciplinary approach via secondary metastatic resection. We present the efficacy data of first-line treatment and the benefit of interdisciplinary collaboration of right-sided metastatic colon carcinoma patients: n = 25. RAS mutation: n = 20 (80%): received systemic first-line treatment: FOLFIRI plus bevacizumab. All-RAS-wildtype: n = 5 (20%): received systemic first-line treatment: FOLFIRI plus cetuximab. Last date evaluation: 31 January 2024. Median age: 59.6 years (range 42-71), men/women: 14/11. Eastern Cooperative Oncology Group (ECOG) index: 0/1/2 : 11/10/4. Evaluable for response: n = 25. Complete response: n = 0, partial response: n = 14 (56%), stable disease: n = 8 (32%), progressive disease: n = 3 (12%), early tumor shrinkage: n = 13 (52%), estimates progression-free survival: 13 months (95% CI 8-17 months), estimated OS: 48 months (95% CI 25-71 months), median follow-up: 26 months (1-61 months), no evidence of disease: n = 4 (16%). A chemotherapy doublette regimen with FOLFIRI plus a biological as first-line treatment shows promising efficacy and secondary metastatic resection after interdisciplinary discussion was associated with a survival benefit in right-sided metastatic colon carcinoma.

Early tumor shrinkage as a prognostic predictor in chemotherapy-naïve patients with locally advanced pancreatic cancer treated with modified FOLFIRINOX or gemcitabine plus nab-paclitaxel combination therapy: An exploratory analysis of JCOG1407

BackgroundEarly tumor shrinkage (ETS) is a prognostic predictor for patients treated with chemotherapy in colorectal cancer, although scarce studies evaluated its potential in locally advanced pancreatic cancer (LAPC). In this exploratory analysis of JCOG1407, a randomized phase II study comparing modified 5-fluorouracil, levofolinate, irinotecan, and oxaliplatin (mFOLFIRINOX) and gemcitabine plus nab-paclitaxel (GnP), we evaluated whether ETS can predict prognosis of patients with LAPC. MethodsOf the 126 patients enrolled in JCOG1407, 112 with measurable lesions were included in this study. ETS was defined as a ≥20 % reduction in tumor diameter compared with baseline at the initial imaging assessment 6–10 weeks after initiating chemotherapy. Patients were divided into the ETS (achieved ETS) and non-ETS (failed to achieve ETS) groups based on their ETS status. The impact of ETS on overall survival (OS) was compared using multivariable Cox regression analysis. ResultsFourteen of 55 (25.5 %) and 24 of 57 (42.1 %) patients in the mFOLFIRINOX and GnP arms, respectively, achieved ETS. In the overall population, mFOLFIRINOX arm, and GnP arm, the median OS in the ETS and non-ETS groups was 27.1 and 20.4, 29.8 and 20.6, and 24.1 and 20.4, months, respectively. The adjusted hazard ratios of OS for the ETS group in the overall population, mFOLFIRINOX arm, and GnP arm were 0.451 (95 % confidence interval [CI]: 0.270–0.754), 0.371 (95 % CI: 0.149–0.926), and 0.508 (95 % CI: 0.255–1.004), respectively. ConclusionsETS may be a prognostic predictor in chemotherapy-naïve patients with LAPC treated with mFOLFIRINOX or GnP.

Early tumor response in first‐line palbociclib plus AI in Chinese women with HR+/HER2- advanced breast cancer: Primary analysis of a multicenter, prospective real-world study.

e13078 Background: The CDK4/6 inhibitors (CDK4/6i) and aromatase inhibitors (AIs) regimen is the first-line standard for HR+/HER2- advanced breast cancer. Despite this, high-risk patients often receive combination chemotherapy for quicker disease control, a practice supported by anecdotal evidence of the efficacy of the CDK4/6i and AI combination but lacking rigorous research validation. Early tumor shrinkage (ETS), a prognostic marker in colorectal cancer, remains undefined in HR+ breast cancer. This study (NCT04858997) aims to investigate the early effectiveness of the CDK4/6i and AI combination through ETS, addressing a significant gap in the literature. Methods: This study enrolled HR+/HER2- advanced breast cancer patients diagnosed between April 2021 and October 2023, who were treatment-naïve for their advanced disease and consented to palbociclib and AI therapy. Participants underwent CT scans to evaluate treatment response at baseline, week 4, week 12, and every 12 weeks thereafter. The study primarily investigated ETS, defined herein as a ≥10% reduction in the sum of diameters of target lesions by week 4. Secondary endpoints encompassed TTR, ORR, and PFS. Results: The study enrolled 30 patients with a median age of 55 years (range 29-76); 30% were premenopausal, and 40% presented with ≥3 metastatic sites. Visceral metastases were observed in 53.3% of the cohort (N=16). ETS was achieved in 73.3% of patients at the first assessment 4 weeks post-treatment initiation, with 68.8% in patients with visceral metastases and 78.8% in those without. The mTTR=3 months, differing between patients with visceral metastases (6 months) and those without (3 months). The overall response rate (ORR) was 63.3%. The ETS outcomes predict the best response in patients, with 77.3% reaching ETS eventually achieving partial or complete response (PR/CR), compared to only 25% of those not reaching ETS. Conclusions: This study validates the CDK4/6i and AI combination's early effectiveness in HR+/HER2- advanced breast cancer, showing that 4-week treatment responses predict best of response outcomes. Achieving ETS is closely linked to a higher likelihood of therapeutic success, underscoring its value as a prognostic marker for informed therapy choices.

Organ-specific tumor dynamics predict survival of patients with metastatic colorectal cancer

BackgroundWe aim to compare the prognostic value of organ-specific dynamics with the sum of the longest diameter (SLD) dynamics in patients with metastatic colorectal cancer (mCRC). MethodsAll datasets are accessible in Project Data Sphere, an open-access platform. The tumor growth inhibition models developed based on organ-level SLD and SLD were used to estimate the organ-specific tumor growth rates (KGs) and SLD KG. The early tumor shrinkage (ETS) from baseline to the first measurement after treatment was also evaluated. The relationship between organ-specific dynamics, SLD dynamics, and survival outcomes (overall survival, OS; progression-free survival, PFS) was quantified using Kaplan-Meier analysis and Cox regression. ResultsThis study included 3687 patients from 6 phase III mCRC trials. The liver emerged as the most frequent metastatic site (2901, 78.7 %), with variable KGs across different organs in individual patients (liver 0.0243 > lung 0.0202 > lymph node 0.0127 > other 0.0118 [week−1]). Notably, the dynamics for different organs did not equally contribute to predicting survival outcomes. In liver metastasis cases, liver KG proved to be a superior prognostic indicator for OS and surpasses the predictive performance of SLD, (C-index, liver KG 0.610 vs SLD KG 0.606). A similar result can be found for PFS. Moreover, liver ETS also outperforms SLD ETS in predicting survival. Cox regression analysis confirmed liver KG is the most significant variable in survival prediction. ConclusionsIn mCRC patients with liver metastasis, liver dynamics is the primary prognostic indicator for both PFS and OS. In future drug development for mCRC, greater emphasis should be directed towards understanding the dynamics of liver metastasis development.

Cetuximab plus FOLFOXIRI versus cetuximab plus FOLFOX as conversion regimen in RAS/BRAF wild-type patients with initially unresectable colorectal liver metastases (TRICE trial): A randomized controlled trial.

It remains unclear whether intensification of the chemotherapy backbone in tandem with an anti-EGFR can confer superior clinical outcomes in a cohort of RAS/BRAF wild-type colorectal cancer (CRC) patients with initially unresectable colorectal liver metastases (CRLM). To that end, we sought to comparatively evaluate the efficacy and safety of cetuximab plus FOLFOXIRI (triplet arm) versus cetuximab plus FOLFOX (doublet arm) as a conversion regimen (i.e., unresectable to resectable) in CRC patients with unresectable CRLM. This open-label, randomized clinical trial was conducted from April 2018 to December 2022 in 7 medical centers across China, enrolling 146 RAS/BRAF wild-type CRC patients with initially unresectable CRLM. A stratified blocked randomization method was utilized to assign patients (1:1) to either the cetuximab plus FOLFOXIRI (n = 72) or cetuximab plus FOLFOX (n = 74) treatment arms. Stratification factors were tumor location (left versus right) and resectability (technically unresectable versus ≥5 metastases). The primary outcome was the objective response rate (ORR). Secondary outcomes included the median depth of tumor response (DpR), early tumor shrinkage (ETS), R0 resection rate, progression-free survival (PFS), overall survival (not mature at the time of analysis), and safety profile. Radiological tumor evaluations were conducted by radiologists blinded to the group allocation. Primary efficacy analyses were conducted based on the intention-to-treat population, while safety analyses were performed on patients who received at least 1 line of chemotherapy. A total of 14 patients (9.6%) were lost to follow-up (9 in the doublet arm and 5 in the triplet arm). The ORR was comparable following adjustment for stratification factors, with 84.7% versus 79.7% in the triplet and doublet arms, respectively (odds ratio [OR] 0.70; 95% confidence intervals [CI] [0.30, 1.67], Chi-square p = 0.42). Moreover, the ETS rate showed no significant difference between the triplet and doublet arms (80.6% (58/72) versus 77.0% (57/74), OR 0.82, 95% CI [0.37, 1.83], Chi-square p = 0.63). Although median DpR was higher in the triplet therapy group (59.6%, interquartile range [IQR], [50.0, 69.7] versus 55.0%, IQR [42.8, 63.8], Mann-Whitney p = 0.039), the R0/R1 resection rate with or without radiofrequency ablation/stereotactic body radiation therapy was comparable with 54.2% (39/72) of patients in the triplet arm versus 52.7% (39/74) in the doublet arm. At a median follow-up of 26.2 months (IQR [12.8, 40.5]), the median PFS was 11.8 months in the triplet arm versus 13.4 months in the doublet arm (hazard ratio [HR] 0.74, 95% CI [0.50, 1.11], Log-rank p = 0.14). Grade ≥ 3 events were reported in 47.2% (35/74) of patients in the doublet arm and 55.9% (38/68) of patients in the triplet arm. The triplet arm was associated with a higher incidence of grade ≥ 3 neutropenia (44.1% versus 27.0%, p = 0.03) and diarrhea (5.9% versus 0%, p = 0.03). The primary limitations of the study encompass the inherent bias in subjective surgical decisions regarding resection feasibility, as well as the lack of a centralized assessment for ORR and resection. The combination of cetuximab with FOLFOXIRI did not significantly improve ORR compared to cetuximab plus FOLFOX. Despite achieving an enhanced DpR, this improvement did not translate into improved R0 resection rates or PFS. Moreover, the triplet arm was associated with an increase in treatment-related toxicity. ClinicalTrials.gov Identifier: NCT03493048.

Feasibility of implementation of the early tumor shrinkage as a potential predictive marker to daily clinical practice in patients with RAS wild type metastatic colorectal cancer, treated with cetuximab - a non-interventional observational study.

With the aim to show the feasibility of early tumor shrinkage (ETS) concept implementation into daily clinical practice in the Czech Republic, a non-interventional, multicentric, single arm, prospective study in real world set-up was performed. The study objectives were to explore the time interval from the treatment starting date to the date of the first radiographic control (TFRC) and evaluate the proportion of patients who achieved ≥ 20% tumor regression within the first 8 weeks of first-line therapy, in the real-world settings. The medians of TFRC in all individual participating centers were > 12 weeks (range 14.0-36.4 weeks). TFRC ≤ 8 weeks was reported for only 3% of patients in the cohort with first-line therapy, and there were only 3 patients (1%) who achieved tumor regression of ≥ 20% by day 60 (8.6 weeks). These findings indicate that the basic time parameter of ETS could not realistically be employed in routine oncology care of patients with metastatic colorectal cancer (mCRC) in the Czech Republic, unless there would be a strict request to perform TRFC by week 8 since the initiation of the therapy. In addition, the frequency of objective tumor response to first-line therapy with cetuximab + chemotherapy was evaluated. Based on the relative regression in the sum of diameters of measurable metastatic lesions, unconfirmed partial responses were achieved in 42.4 % and unconfirmed complete response in 8.6% of patients, altogether corresponding to the overall response rate of 51% with first-line therapy. The frequency of responses was higher among patients with left than right sided primary tumors. It seems that the regimen of cetuximab/FOLFOX might be more active in frontline therapy of right sided RAS wild type mCRC than cetuximab/FOLFIRI.

First-line pembrolizumab plus chemotherapy for advanced/metastatic esophageal cancer: 1-year extended follow-up in the Japanese subgroup of the phase 3 KEYNOTE-590 study

BackgroundFirst-line pembrolizumab plus chemotherapy (pembrolizumab–chemotherapy) demonstrated improved efficacy and a manageable safety profile versus placebo plus chemotherapy (placebo–chemotherapy) in the subgroup analysis of Japanese patients with advanced/metastatic esophageal cancer in KEYNOTE-590 at a median follow-up of 24.4 months. Longer-term data from the Japanese subgroup analysis of KEYNOTE-590 are reported.MethodsPatients were randomly assigned 1:1 to pembrolizumab 200 mg or placebo every 3 weeks for ≤ 35 cycles plus chemotherapy (cisplatin 80 mg/m2 and 5-fluorouracil 800 mg/m2/day). Endpoints included overall survival (OS) and progression-free survival (PFS; investigator-assessed per RECIST v1.1; dual primary) and safety (secondary). Early tumor shrinkage (ETS) and depth of response (DpR) were assessed post hoc.ResultsOverall, 141 patients were enrolled in Japan. As of July 9, 2021, median follow-up was 36.6 months (range, 29.8–45.7). Pembrolizumab–chemotherapy showed a trend toward favorable OS (hazard ratio [HR], 0.70; 95% confidence interval [CI] 0.47–1.03) and PFS (0.57; 0.39–0.83) versus placebo–chemotherapy. In the pembrolizumab–chemotherapy group, patients with ETS ≥ 20% (55/74; 74.3%) versus < 20% (19/74; 25.7%) had favorable OS (HR, 0.23; 95% CI 0.12–0.42) and PFS (0.24; 0.13–0.43). Patients with DpR ≥ 60% (31/74; 41.9%) versus < 60% (43/74; 58.1%) had favorable OS (HR, 0.37; 95% CI 0.20–0.68) and PFS (0.24; 0.13–0.43). Grade 3–5 treatment-related adverse events occurred in 55/74 patients (74.3%) with pembrolizumab–chemotherapy and 41/67 patients (61.2%) with placebo–chemotherapy.ConclusionsWith longer-term follow-up of Japanese patients with advanced/metastatic esophageal cancer, efficacy continued to favor pembrolizumab–chemotherapy compared with placebo–chemotherapy, with no new safety signals observed.Clinical trial registration: ClinicalTrials.gov, NCT03189719.

Switching from FOLFIRI plus cetuximab to FOLFIRI plus bevacizumab based on early tumor shrinkage in RAS wild-type metastatic colorectal cancer: A phase II trial (HYBRID).

Long-term anti-EGFR antibody treatment increases the risk of severe dermatologic toxicities. This single-arm, phase II trial aimed to investigate the strategy of switching from cetuximab to bevacizumab in combination with FOLFIRI based on early tumor shrinkage (ETS) in patients with RAS wild-type metastatic colorectal cancer (mCRC). Radiologic assessment was performed to evaluate ETS, defined as ≥20% reduction in the sum of the largest diameters of target lesions 8 weeks after the introduction of FOLFIRI plus cetuximab. ETS-negative patients switched to FOLFIRI plus bevacizumab, whereas ETS-positive patients continued FOLFIRI plus cetuximab for eight more weeks, with a switch to FOLFIRI plus bevacizumab thereafter. The primary endpoint was progression-free survival. This trial was prematurely terminated due to poor accrual after a total enrollment of 30 patients. In 29 eligible patients, 7 were ETS-negative and 22 were ETS-positive. Two ETS-negative patients and 17 ETS-positive patients switched to FOLFIRI plus bevacizumab 8 weeks and 16 weeks after initial FOLFIRI plus cetuximab, respectively. Median progression-free and overall survival durations were 13.4 and 34.7 months, respectively. Six (20%) patients experienced grade ≥3 paronychia, which improved to grade ≤2 by 18 weeks. Grade ≥3 acneiform rash, dry skin, and pruritus were not observed in any patients. Our novel treatment strategy delivered acceptable survival outcomes and reduced severe dermatologic toxicities.

Abstract 2129: Efficacy and underlying mechanisms of surufatinib combined with PD-1 monoclonal antibody and chemotherapy in pancreatic cancer

Abstract Background: A phase 1b/2 study (NCT05218889) of surufatinib combined with camrelizumab, nab-paclitaxel, and S-1 (NASCA) as first-line therapy for metastatic pancreatic adenocarcinoma has shown promising results, potentially overcoming the limitations of current pancreatic immunotherapies. Animal studies are underway to further explore the synergistic effects and mechanisms of this combined therapeutic approach. Methods: Genetically engineered KPC mouse cells were used to establish a subcutaneous transplantation tumor model in female mice, which were then divided into control group, AG group (nab-paclitaxel + gemcitabine), and NASCA group. Tumor metrics were recorded until euthanasia after 21 days. Blood and tumor samples were analyzed using Flow Cytometry. Results: Compared with the control group, the NASCA and AG groups demonstrated tumor volume reductions of 14.7% (p=0.172) and -0.4% (p=0.972) on day 7, respectively. At day 14, the reductions were 48.8% and 29.9% (p&amp;lt;0.001*, p=0.002*). At day 21, the reductions were 37.4% and 21.5% (p=0.001*, p=0.144). The tumor growth inhibitions (TGIs) for NASCA and AG group were 56.7% (p&amp;lt;0.001*) and 21.2% (p=0.36), respectively. Compare to AG group, the tumor volume reduction in NASCA group were 15.1% (p=0.050*), 26.9% (p=0.001*) and 20.3% (p=0.116), respectively. And the TGIs for NASCA group compare AG group was 45.0% (p=0.020*). Distinguishingly, the NASCA group, when compared to the AG group, had a heightened proportion of M1 macrophages (28.5% vs. 15.5%, p=0.019*), mCD68+ Macrophages (99.7% vs. 99.1%, p=0,014*) and mPD-1+/mCD8+ T cells (24.8% vs. 9.8%, p=0.03*). Furthermore, T-regulatory cells (T-regs) in peripheral blood demonstrated uniformity across the groups, were no statistically. RNA-seq analysis revealed that the NASCA significantly suppressed multiple anti-angiogenic pathways while enhancing the cytokine pathway (p=0.005*), indicating potential immune system activation. Conclusion: The NASCA group outperformed the AG group in controlling tumor growth and early tumor shrinkage, potentially due to macrophage polarization regulation. Further research is vital to understand the benefits of integrating targeted therapy, immunotherapy, and chemotherapy for pancreatic cancer. Citation Format: Nan Zhang, Ru Jia, Guanghai Dai. Efficacy and underlying mechanisms of surufatinib combined with PD-1 monoclonal antibody and chemotherapy in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2129.

Impact of early tumor shrinkage and depth of response in patients with BRAF V600E-mutant metastatic colorectal cancer.

142 Background: Early tumor shrinkage (ETS) and the depth of response (DpR) are early on-treatment surrogate markers for survival in patients with metastatic colorectal cancer (mCRC) receiving anti-epidermal growth factor receptor (EGFR) monoclonal antibody. However, the utility of ETS and DpR for BRAF V600E mutant (MT) mCRC which has a poor prognosis remains unclear. The aim of this study is to evaluate the association between ETS and DpR and clinical outcomes in BRAF V600E MT mCRC. Methods: mCRC patients who were diagnosed BRAF V600E MT and treated with 1st line chemotherapy from June 2011 to March 2023 at single cancer institute were enrolled. We analyzed the association between ETS and DpR and clinical outcome in patients who had at least one target lesion. Subgroup analysis of clinical factors related to progression free survival (PFS) and overall survival (OS) was performed using multivariate analysis. ETS was defined as the relative change in the sum of the longest diameters of RECIST target lesions at first follow-up CT scan compared to baseline and DpR was defined as the relative change in the sum of the longest diameters of RECIST target lesions at the nadir in the absence of new lesions or progression of non-target lesions compared to baseline. Results: In total, 54 patients of BRAF V600E MT mCRC had at least one target lesion. In total of StageI-IV CRC patients, the incidence of BRAF V600E MT was 6.3% (233/3705). Patients with ETS ≥ 20% and DpR ≥ 25% (median value) were 24 (44.4%) and 27 (50%) respectively. PFS was 7.5 months (95% confidence interval (CI), 5.0-9.9) and OS was 17.1 months (95% CI, 11.7-20.2). Patients with ETS ≥ 20% had longer PFS and tended to have longer OS than those with non-ETS, with a median PFS of 9.8 months vs. 4.8 months (P Log-rank = 0.048, hazard ratio (HR), 0.55; 95% CI, 0.30-1.00), and a median OS of 22.6 months vs. 11.6 months (P Log-rank = 0.18, HR, 0.67; 95% CI, 0.37-1.21). Patients with DpR ≥ 25% had also longer PFS and OS than those with non-DpR, with a median PFS of 11.0 vs. 4.3 months (P Log-rank &lt; 0.01, HR, 0.36; 95% CI, 0.20-0.66) and a median OS of 22.6 vs. 10.1 months (P Log-rank = 0.047, HR, 0.55; 95% CI, 0.31-1.00). Median time to DpR was 3.05 months. In multivariate analysis, DpR was significantly associated with both longer PFS (HR: 0.27, 95% CI: 0.14–0.55, P &lt; 0.01) and OS (HR: 0.52, 95% CI: 0.29–0.96, P = 0.04). Conclusions: ETS and DpR may be early surrogate markers for clinical outcome in BRAF V600E MT mCRC who were treated with 1st line chemotherapy.

Impact of acquired RAS, BRAF and PIK3CA mutation at 8 weeks on the efficacy of anti-EGFR monoclonal antibodies in metastatic colorectal cancer.

193 Background: Recent studies indicate that the emergence of RAS/BRAF mutation sometimes occurs during initial anti-EGFR monoclonal antibody (mAb)-based treatment in metastatic colorectal cancer (mCRC). However, limited data was available regarding the timing and frequency of the emergence of RAS/BRAF mutation, and its impact on the efficacy of anti-EGFR mAb. With this background, we conducted an observational study to monitor RAS, BRAF, and PIK3CA mutation status by ctDNA in RAS/BRAF wt mCRC. Methods: RAS-trace is a pilot study to monitor RAS, BRAF, and PIK3CA mutation status by ctDNA, using NGS-based Plasma-Safe-SeqS technology for RAS/BRAF wt (diagnosed from tissue samples) mCRC treated with anti-EGFR mAb as a first-line chemotherapy. ctDNA- RAS/BRAF/PIK3CA status evaluated at baseline, 8, 12, 16, 20, 24, 36, 48 weeks and disease progression. The primary endpoint was the time to the acquired RAS mutations. The results of ctDNA at baseline and 8 weeks are presented. Results: Forty-two patients were enrolled, and 40 and 39 were used in the analysis of ctDNA at baseline and 8 weeks, respectively. All patients received mFOLFOX6 plus cetuximab (N=32) or panitumumab (N=8). At baseline, RAS, BRAF, and PIK3CA mutations were detected in 3, 3, and 1 of the 40 patients, respectively. One patient had both KRAS and BRAF mutations. Baseline ctDNA mutations were not associated with the presence of liver metastases, tumor sidedness, early tumor shrinkage, depth of response or skin rash ≥Grade 2. At 8 weeks, RAS, BRAF, and PIK3CA mutations were detected in 3, 2, and 0 among the 39 patients, respectively. One patient had both KRAS and BRAF mutations. ctDNA mutations at 8 weeks were not associated with the presence of liver metastases, tumor sidedness, or early tumor shrinkage, however, they were associated with depth of response and had a tendency of skin rashes ≥ Grade 2 (Table). Conclusions: Emergence of RAS/BRAF/PIK3CA mutations at 8 weeks may be related to the response of anti-EGFR mAb. The association of ctDNA status with survival outcomes will be presented in 2025. Clinical trial information: jRCT1050210160 . [Table: see text]

Efficacy of bevacizumab combined with apatinib in the treatment of advanced metastatic gastric cancer.

To evaluate the clinical efficacy and safety of bevacizumab combined with apatinib in the treatment of advanced metastatic gastric cancer, providing insights for treatment decisions. We conducted a single-center retrospective study involving patients with metastatic gastric cancer treated with apatinib, with or without bevacizumab, between August 2018 and April 2021 at Nanchang Medical College. Data on efficacy, adverse events, response rates, and quality of life were collected and compared. No significant differences were observed in complete remission, partial response, stable disease, disease progression, objective response rate, or disease control rate between the groups (all P>0.05). The median progression-free survival was 9.23 months in the control group and 9.94 months in the observation group (P=0.587). Median overall survival (OS) was 19.64 months in the control group and 26.44 months in the observation group (P=0.187). Univariate and multivariate analyses identified combination therapy with apatinib and bevacizumab, primary lesion resection, and number of metastatic organs as independent prognostic factors for OS. Scores for role, emotional, somatic, cognitive, and social functions were significantly higher in the observation group post-intervention (all P<0.05). In patients with advanced metastatic gastric cancer, combined therapy with bevacizumab and apatinib significantly improved OS, enhanced response rates, and increased rates of early and maximal tumor shrinkage.

Clinical Impact of Early Tumour Shrinkage in Metastatic or Unresectable Oesophageal Cancer Treated with Pembrolizumab plus Chemotherapy

Introduction: Metastatic or unresectable locally advanced oesophageal cancer remains a disease with high mortality. More recently, pembrolizumab plus chemotherapy has been indicated as the first-line treatment for those patients, but the predictive factors for treatment efficacy remain controversial. This study investigated the clinical utility of early tumour shrinkage (ETS) and depth of response (DpR) in metastatic or unresectable oesophageal cancer treated with pembrolizumab plus CF therapy. Methods: ETS and DpR, defined as the percent decreases at the second evaluation and the percentage of the maximal tumour shrinkage during treatment, were measured in 53 eligible patients. The ETS and DpR cut-off values were 20% and 30%, respectively, based on survival outcomes. Results: Twenty-seven patients (51%) were treatment naïve, while 26 (49%) had received any treatment before initiating pembrolizumab plus CF therapy. The median progression-free survival (PFS) and overall survival for ETS ≥20% and <20% were 12.7 and 5.5 months and 14.4 and 8.2 months and 12.7 and 4.9 months and 14.4 and 8.0 months for DpR ≥30% and <30%, respectively. ETS <20% showed early tumour growth, whereas ETS ≥20% had a good response rate with sufficient longer response duration. In addition, an ETS cut-off of 20% predicted the best overall response and was not associated with prior treatment. In multivariable analysis, ETS ≥20% and DpR ≥30% were independent factors of longer PFS. Conclusion: Our findings suggest that an ETS is a promising on-treatment marker for early prediction of further sensitivity to pembrolizumab plus CF therapy.

151P Relationship between depth of response and early tumor shrinkage with overall survival in advanced pancreatic cancer

151P Relationship between depth of response and early tumor shrinkage with overall survival in advanced pancreatic cancer

PS4-4 Early tumor shrinkage and depth of response with first-line panitumumab or bevacizumab and mFOLFOX treatment in PARADIGM

PS4-4 Early tumor shrinkage and depth of response with first-line panitumumab or bevacizumab and mFOLFOX treatment in PARADIGM

Ramucirumab plus FOLFIRI as second-line treatment for patients with RAS wild-type metastatic colorectal cancer previously treated with anti-EGFR antibody: JACCRO CC-16

Chemotherapy in combination with anti-epidermal growth factor receptor (EGFR) antibody is considered a first-line treatment regimen for RAS wild-type and left-sided metastatic colorectal cancer (mCRC), whereas second-line treatment regimens have not yet been established. Few studies have prospectively evaluated second-line treatment with anti-vascular endothelial growth factor antibody after first-line anti-EGFR antibody therapy for RAS wild-type mCRC. This non-randomized phase II trial investigated the clinical outcomes of second-line ramucirumab (RAM) plus fluorouracil, levofolinate, and irinotecan (FOLFIRI) after first-line anti-EGFR antibody in combination with doublet or triplet regimen in patients with RAS wild-type mCRC. The primary endpoint was the 6-month progression-free survival (PFS) rate. The secondary endpoints were PFS, overall survival (OS), objective response rate (ORR), rate of early tumor shrinkage (ETS), and safety. We hypothesized a threshold 6-month PFS rate of 30% and an expected 6-month PFS rate of 45%. Treatment was considered effective if the lower limit of the 90% confidence interval (CI) of the 6-month PFS rate was >0.30. Ninety-two patients were enrolled in the study. The primary tumor was located on the left side in 86 (95.6%) patients. Twenty (22.0%) patients had received triplet plus cetuximab as previous therapy. Six-month PFS rate was 58.2% (90% CI 49.3% to 66.2%) with a median PFS of 7.0 months (95% CI 5.7-7.6 months). Median OS was 23.6 months (95% CI 16.5-26.3 months). The ORR and ETS rate were 10.7% and 16.9%, respectively, in 83 patients with measurable lesions. The 6-month PFS rate was comparable between patients previously treated with doublet and triplet regimens; however, median PFS was longer for the doublet regimen (7.4 versus 6.4 months, P= 0.036). Our study demonstrated prospectively that RAM plus FOLFIRI is an effective second-line treatment after anti-EGFR antibody-containing first-line therapy in RAS wild-type and left-sided mCRC. Furthermore, the results were similar for patients who were previously treated with triplet regimen.

Early Tumor Shrinkage and Depth of Response as Predictors of Survival for Advanced Biliary Tract Cancer: An Exploratory Analysis of JCOG1113.

Recent studies suggest that early tumor shrinkage (ETS) and depth of response (DpR) reflect outcomes of chemotherapy in various cancers. This study evaluated the association of ETS and DpR with clinical outcomes using data from JCOG1113, which demonstrated the non-inferiority of gemcitabine plus S-1 (GS) to gemcitabine plus cisplatin (GC) for chemotherapy-naïve advanced biliary tract cancer. In total, 354 (289 with measurable target lesions) patients enrolled in JCOG1113 were divided into ETS-unachieved and ETS-achieved groups (≥20% tumor reduction at week 6) and DpR-low and DpR-high groups (≥40% maximum shrinkage) until 12 weeks after enrollment. The impact of ETS and DpR on survival outcome was evaluated using the multivariable Cox proportional hazard model. The proportions of patients in the ETS-achieved and DpR-high groups were similar between the 2 treatment arms. The hazard ratios (HRs) of progression-free survival (PFS) and overall survival (OS) for the ETS-achieved group were 0.70 (95% confidence interval (CI), 0.52-0.93) and 0.60 (95%CI, 0.44-0.81), respectively. The HRs of PFS and OS for the DpR-high group were 0.67 (95%CI, 0.48-0.94) and 0.64 (95%CI, 0.46-0.90), respectively. In the subpopulation treatment effect pattern plot analysis, most patients in the ETS-achieved group in the GC arm did not experience disease progression after 12 weeks from the landmark. As on-treatment markers, ETS and DpR were effective tools. ETS was clinically useful, because it can be used to evaluate the outcomes of treatment early at a specific time.