PET Response Assessment Research Articles

17th International Conference on Malignant Lymphoma, Palazzo dei Congressi, Lugano, Switzerland, 13 - 17 June, 2023.

Introduction: Diffuse large B-cell lymphoma (DLBCL) is an aggressive but potentially curable lymphoma. Rituximab, cyclophosphamide, vincristine, doxorubicin and prednisone (R-CHOP) is the standard first-line regimen with cure rates nearing 60%. Over the last years many efforts have been made aiming at improving outcomes of first line therapy but none has resulted in improved overall survival over R-CHOP. Recently, genetic subtypes of DLBCL that go beyond the cell-of-origin and have distinct biology, clinical characteristics and different likelihood of response to specific therapies have been identified. One of these entities is represented by the MCD subtype harboring either the MYD88 L265P mutation, the CD79A/B mutation, or both. MCD has a dismal outcome when treated with R-CHOP but is sensitive to BTK inhibition. In addition to the genetic definition of specific subtypes, the possibility to use circulating tumour DNA (ctDNA) response assessment together with PET-response may establishe a new strategy for treatment decisions in patients with DLBCL. Methods: SAKK 38/19 (NCT04604067) is an ongoing exploratory multicohort phase II trial in patients (pts) with previously untreated DLBCL not otherwise specified (NOS). Adult pts with CD20-positive DLBCL NOS, ECOG performance status 0–2, candidates for 6 cycles of R-CHOP are eligible. At baseline, a liquid biopsy is perfomed and pts with MCD subtype are treated with the combination of R-CHOP plus acalabrutinib for 6 cycles (cohort A). Non-MCD pts receive 2 cycles of R-CHOP and based on the combined PET and ctDNA response assessment after cycle 2 they are allocated to one of three different cohorts: R-CHOP for 4 additional cycles in combination with acalabrutinib followed by 2 months of acalabrutinib single-agent (cohort B); 2 additional cycles of R-CHOP and 2 administrations of single-agent rituximab (cohort C); 4 additional cycles of R-CHOP (cohort D). Co-primary endpoints of the trial are: Progression free survival (PFS) (in Cohorts A, C and D) and complete remission (CR) rate (in Cohort B) Secondary endpoints: Adverse events in the cohorts treated with acalabrutinib-R-CHOP; overall survival; PFS in cohort B; CR rate in cohorts A, C and D; overall response rate; duration of response. The research was funded by: -Astra Zeneca -Hubacher Fund Keywords: aggressive B-cell non-Hodgkin lymphoma, liquid biopsy, ongoing trials Conflicts of interests pertinent to the abstract A. Stathis Honoraria: Eli Lilly, Bayer, Roche, Novartis, Janssen Oncology, AstraZeneca Research funding: ADC Therapeutics, Pfizer, Roche, Novartis, Bayer, Eli Lilly, MEI Pharma, Cellestia, Debiopharm Group, Merck/MSD, Abbvie, Amgen, AstraZeneca, Incyte, Loxo, and Philogen F. Hitz Consultant or advisory role Abbvie, Takeda and Roche G. Gritti Consultant or advisory role Roche, Takeda, Kite-Gilead, Ideogen, Genmab Educational grants: Janssen, Beigene, Sandoz Other remuneration: Clinigen, Ideogen, Beigene, Incyte, Novartis T. Zenz Honoraria: Roche, Abbvie, AZD, Beigene, Janssen, Gilead, Novartis

PROGNOSTIC SIGNIFICANCE OF SEQUENTIAL 18F‐FDG PET/CT DURING THE TREATMENT OF ANTHRACYCLINE‐CONTAINING FRONTLINE CHEMOTHERAPY IN PERIPHERAL T CELL LYMPHOMAS

Introduction: Despite the prognostic significance of 18F-fluorodeoxyglucose (FDG)-positron emission tomography-computed tomography (PET/CT) assessment has important implications on determining the response-adapted therapy in patients with peripheral T-cell lymphomas (PTCLs), an optimal timing of the use and clinical application of PET/CT-based response are still up in the air. The aim of this study was to explore the prognostic impact of sequential 18F-FDG PET/CT analysis in patients with newly diagnosed PTCLs who treated with frontline anthracycline-based chemotherapy. Methods: Between February 2006 and September 2022, 143 patients with newly diagnosed PTCLs were included. All patients were treated with 6 cycles of anthracycline-containing chemotherapy. Sequential 18F-FDG PET/CT were obtained at the time of diagnosis, after three cycles of chemotherapy and finally at the end of chemotherapy. Baseline total metabolic tumor volume (TMTV) was computed with the sum of SUV2.5 threshold method, and the PET/CT response were assessed using the five-point scale (5-PS) of Deauville criteria. Results: Baseline MTV could be calculated in 126 patients, and the cut-off value of TMTV according to ROC analysis was 457.0 cm3 (Sensitivity 45.0%, specificity 74.0%). With a median follow-up of 52.0 months (range 3.8–153.9 months), patients with high TMTV more than cut-off value had inferior PFS and OS than those with low TMTV (PFS, 9.8 months vs. 26.5 months, HR 1.600, 95% CI 1.010–2.671, p = 0.043; OS, 18.9 months vs. 71.2 months, HR 2.135, 95% CI 1.261–3.615, p = 0.004, Figure 1A, B). Interim 18F-FDG PET/CT assessment was available in all 143 patients. When patients were categorized with three subgroups as response with grade 1, grade 2 and 3, and grade 4–5, PFS and OS showed significant difference according to interim visual assessment (PFS, 120.7 months vs. 34.1 months vs. 5.1 months, p < 0.001; OS, not reached vs. 61.1 months vs. 12.1 months, p < 0.001, Figure 1C, D), respectively. Among 77 patients who were assessed as grade 2 or 3 in interim PET/CT analysis, 19 patients (26.3%) turned over a remnant tumor metabolism or progressed at final PET response assessment. Moreover, the outcome of patients with interim grade 2 or 3 showed the significant differences based on the final achievement of complete metabolic response or not in PFS and OS (PFS, 59.9 months vs. 7.2 months, HR 4.754, 95% CI 2.267–9.971, p < 0.001; OS, not reached vs. 24.0 months, HR 3.706, 95% CI 1.592–8.630, p = 0.001), respectively. Keywords: aggressive T-cell non-Hodgkin lymphoma, diagnostic and prognostic biomarkers No conflicts of interests pertinent to the abstract.

PET-guided treatment for personalised therapy of Hodgkin lymphoma and aggressive non-Hodgkin lymphoma.

FDG-PET scanning has a central role in lymphoma staging and response assessment. There is a growing body of evidence that PET response assessment during and after initial systemic therapy can provide useful prognostic information, and PET response has an evolving role in guiding patient care. This review provides a perspective on the role of PET response assessment for individualised management of patients with the most common aggressive lymphomas, Hodgkin lymphoma and diffuse large B-cell lymphoma.

PET/CT-tailored treatment of locally advanced oesophago-gastric junction adenocarcinoma: a report on the feasibility of the multicenter GastroPET study.

Background:Perioperative chemotherapy is a recommended treatment approach for localised oesophago-gastric junction adenocarcinoma, but not all patients respond to neoadjuvant chemotherapy. Early identification of non-responders and treatment adaptation in the preoperative period could improve outcomes. GastroPET is a national, multicentre phase II trial evaluating a 18FDG-PET/CT-guided preoperative treatment strategy with the R0 resection rate as a primary endpoint. Here, we report on the accuracy of the methodology, the feasibility of the study design and patient safety data after enrolment of the first 63 patients.Methods:Patients with locally advanced oesophago-gastric junction adenocarcinoma (Siewert I – III) stage Ib–IIIc underwent baseline 18FDG-PET/CT scanning and re-evaluation after 14 days of oxaliplatinum-5FU-(docetaxel) chemotherapy. Responders were defined by a ⩾ 35% decrease in tumour FDG standardised uptake value (SUV)average from baseline. Responders continued with the same chemotherapy for 2 to 3 months prior to surgery. PET-non-responders switched to preoperative chemoradiotherapy [weekly carboplatin and paclitaxel with concurrent radiotherapy (45 Gy in 25 fractions)]. Here, we aim to confirm the feasibility of FDG-PET-based response assessment in a multicenter setting and to compare local versus central reading. In addition, we report on the feasibility of the study conduct and patient safety data.Results:A total of 64 patients received baseline and sequential 14-day 18FDG-PET/CT scanning. And, 63 were allocated to the respective treatment arm according to PET-response [35 (56%) responders and 28 (44%) non-responders]. The concordance of local versus central reading of SUV changes was 100%. Until the date of this analysis, 47 patients (28 responders and 19 non-responders) completed surgery. Postoperative complications of grade ⩾ 3 (Common Terminology Criteria for Adverse Events, CTCAE Version 5.0) were reported in five responders (18%; 95% CI: 7.9–36%) and two non-responders (11%; 95% CI: 2.9–31%), with no statistical difference (p = 0.685). One patient in each arm died after surgery, leading to a postoperative in-hospital mortality rate of 4.3% (2/47 patients; 95% CI: 1.2–14%).Conclusion:Local and central FDG-SUV quantification and PET-response assessment showed high concordance. This confirms the accuracy of a PET-response-guided treatment algorithm for locally advanced oesophago-gastric junction cancer in a multicenter setting. Preoperative treatment adaptation revealed feasible and safe for patients.

1896MO Volumetric PET response assessment outperforms conventional criteria in patients receiving high-dose pembrolizumab for malignant mesothelioma

Fixed-dose pembrolizumab (200 mg abs., d1, q3w) for the treatment of malignant pleural mesothelioma did not result in survival benefit in the phase 3 PROMISE-meso trial compared to 2nd-line chemotherapy. Due to lack of validated imaging response criteria, responder-subgroups with potential survival benefit have not yet been identified. Here, we administered high-dose pembrolizumab (10 mg/kg, d1, q2w) considering the KEYNOTE-028 trial and assessed the prognostic value of PET metabolic response in patients with chemotherapy-resistant malignant mesothelioma of the pleura or peritoneum. Data from 27 patients with baseline and follow-up 18F-FDG PET/CT imaging were retrospectively analyzed. RECIST v1.1, mRECIST, PERCISTSULpeak and PERCISTMTV were used separately to categorize responders in CT and PET imaging studies. Progression-free survival (PFS) and overall survival (OS) of responders were compared to non-responders using Kaplan-Meier and log-rank analyses. Programmed Cell Death Protein 1 (PD-L1) expression status was assessed and its association with outcome was investigated. 27 patients had 18F-FDG-PET/CT imaging at baseline and after at least 4 cycles pembrolizumab. Median PFS and OS were 3.4 and 15.1 months, respectively. Response rates were 7%, 7%, 30%, and 30% based on RECIST v1.1, mRECIST, PERCISTSULpeak, and PERCISTMTV response criteria, respectively. Response according to PERCISTMTV predicted prolonged OS or PFS (p < 0.01), whereas all other imaging criteria and PD-L1 expression did not. 18F-FDG PET metabolic volume response predicts survival in patients with malignant mesothelioma receiving high-dose pembrolizumab. These results should prompt inclusion of PET response assessment in future phase 3 clinical trials.

Volumetric PET Response Assessment Outperforms Conventional Criteria in Patients Receiving High-Dose Pembrolizumab for Malignant Mesothelioma.

Fixed-dose pembrolizumab (200 mg absolute, day 1, every 3 wk) for the treatment of malignant pleural mesothelioma did not result in survival benefit in the phase 3 PROMISE-meso trial compared with second-line chemotherapy. Because of lack of validated imaging response criteria, responder subgroups with potential survival benefit have not yet been identified. Here, we administered high-dose pembrolizumab (10 mg/kg, day 1, every 2 wk) considering the KEYNOTE-028 trial and assessed the prognostic value of PET metabolic response in patients with chemotherapy-resistant malignant mesothelioma of the pleura or peritoneum. Methods: Data from 27 patients with baseline and follow-up 18F-FDG PET/CT imaging were retrospectively analyzed. RECIST, version 1.1; modified RECIST; and PERCIST using both tumor lesion metabolic activity in a 1 cm3 spheric region of interest of up to 5 target lesions (PERCISTSULpeak) and metabolic tumor volume PERCIST (PERCISTMTV) were applied separately to categorize responders in CT and PET imaging studies. Progression-free survival (PFS) and overall survival (OS) were compared between responders and nonresponders using Kaplan-Meier and log-rank analyses. Programmed cell death protein 1 ligand expression status was assessed, and its association with outcome was investigated. Results: Twenty-seven patients had 18F-FDG PET/CT imaging at baseline and after at least 4 cycles pembrolizumab. Median PFS and OS were 3.4 and 15.1 mo, respectively. Response rates were 7%, 7%, 30%, and 30% based on RECIST, modified RECIST, PERCISTSULpeak, and PERCISTMTV response criteria, respectively. Response according to PERCISTMTV predicted prolonged OS or PFS (P < 0.01), whereas all other imaging criteria and programmed cell death protein 1 ligand expression did not. Conclusion:18F-FDG PET metabolic volume response predicts survival in patients with malignant mesothelioma receiving high-dose pembrolizumab. These results should prompt inclusion of PET response assessment in future phase 3 clinical trials.

Real-World Data of High-Grade Lymphoma Patients Treated with CD19 CAR-T in England

Real-World Data of High-Grade Lymphoma Patients Treated with CD19 CAR-T in England

AvR-CHOP: Feasibility Study of Induction and Maintenance Avelumab Plus R-CHOP in Patients with Diffuse Large B-Cell Lymphoma (DLBCL)

Background: Whilst up to 60% of DLBCL patients (pts) are cured with frontline R-CHOP (rituximab, cyclophosphamide, doxorubicin, vincristine, prednisone), outcomes remain poor for those with relapsed or refractory disease. 1 New strategies to improve frontline cure rates are needed. Tumour cells exploit immune checkpoint pathways, including the PD1/PDL1 axis, to evade the host immune system. PD1/PDL1 over-expression and cytogenetic 9p24 alterations in some DLBCL subtypes provide additional rationale for immune checkpoint inhibition (ICI) in this disease. Although single agent PD1 inhibition yields an overall response rate (ORR) of only 10%-30% in heavily pre-treated unselected DLBCL, many responses are durable.2 Immunosuppressive effects of prior therapy may contribute to the modest response to ICI in relapsed disease. A number of considerations influence the incorporation of ICI into upfront DLBCL treatment. Although concurrent PD1/PDL1 inhibition and R-CHOP is safe,3 corticosteroid-related immunosuppression may negate PDL1-inhibitor efficacy. Evidence supporting host immune priming with ICI prior to chemotherapy is promising,4 and maintenance ICI post chemotherapy may assist with immune reconstitution and enhance the anti-tumour immune response. Additionally, avelumab (Av, an anti-PDL1 monoclonal antibody with antibody dependent cellular cytotoxicity activity) acts synergistically with rituximab (R) in vitro (unpublished data, Pfizer 2016). Thus, we present our phase II study assessing the safety of sequential Av+R induction, R-CHOP and Av maintenance as upfront therapy for DLBCL. Methods: AvR-CHOP (NCT03244176) is a phase II multicentre single-arm trial of Av induction + maintenance with R-CHOP in newly-diagnosed adult pts with DLBCL. Pts aged &gt;18 years, ECOG 0-2, stage II-IV and with no active autoimmune disease are eligible. Exclusion criteria include the necessity for urgent cytoreduction, grade 3B or transformed follicular lymphoma, CNS involvement, chronic steroid use, prior transplantation or pneumonitis. Treatment (Fig 1) comprises R (375mg/m2 IV) + Av (10mg/kg IV) x 2 cycles q2-weekly, followed by R-CHOP21 x 6 cycles. Maintenance Av x 6 cycles q2-weekly is given to patients achieving a complete metabolic response by PET/CT at the end of R-CHOP. PET/CT is performed after R+Av 2 cycles, cycle 2 R-CHOP, end of R-CHOP and end of Av maintenance. The primary endpoint is immune-related toxicity within 30 days post-treatment. Secondary endpoints include ORR, failure free survival (FFS), overall survival (OS) and toxicity of treatment. Complete metabolic response rates by PET-CT after R-Av induction and after C2 R-CHOP are exploratory endpoints. Biomarker sample collection is synchronised with PET response assessment. A comprehensive translational substudy will apply high throughput technologies to tissue and sequential blood samples to characterise the tumour-immune system interaction and correlate novel host, tumour and tumour microenvironment factors with treatment responses and toxicity. Planned enrolment is 28 pts across 3 sites in Australia. The study follows a Simon 1 stage design, with an 80% power and a 1-sided alpha of 0.05 to rule out an Av-related toxicity rate of 30% (p0=70%), assuming an expected immune related toxicity rate of 10% [p1=90%]. 23 pts are enrolled to date. Acknowledgements: Merck KgA (avelumab and funding)

Phase I Dose Escalation Study of Radiotherapy and Durvalumab (MEDI4736) in Relapsed/Refractory Diffuse Large B-Cell Lymphoma (DLBCL): The RaDD Study

Background: Although ~60% of patients with DLBCL are cured with frontline therapy, outcomes for those with relapsed/refractory disease remain poor. Tumour cells exploit immune checkpoint pathways, including the PD1/PDL1 axis, to evade and inhibit host anti-tumour immune responses. PD1/PDL1 expression and cytogenetic 9p24 alterations in some DLBCL subtypes provide additional rationale for PDL1 inhibition (PD-L1i) in DLBCL. Though single agent PD1i yields a disappointing ORR of 10-30% in heavily pre-treated DLBCL, some responses are durable.1 Radiotherapy (RT) is an established mechanism of stimulating anti-tumour immunity via increased circulating tumour antigen, immunogenic cell death and T-cell recruitment and activation in the tumour microenvironment. Synergy between concomitant immune checkpoint inhibition (ICI) and RT has been demonstrated in preclinical studies2 and solid tumours; a recent study in non-small cell lung cancer demonstrated an ORR of 36% with pembrolizumab + RT compared with 18% with pembrolizumab alone.3 RT hypofractionation appears critical to the abscopal effect when used with ICI,4 and concurrent RT and PD-L1i is more successful than sequential treatment.5 RT to multiple sites may broaden the spectrum of tumour antigen released and overcome clonal variation between disease sites; a dose-response relationship between RT and antigen release has yet to be established. This phase I study aims to determine the safety profile of escalating dose and number of sites of RT in combination with Durvalumab (MEDI4736), an anti-PD-L1 monoclonal antibody, in relapsed/refractory DLBCL, including primary refractory DLBCL and transformed follicular lymphoma. Study Design and Methods: RaDD (NCT03610061) includes eligible pts who have received ≥1 prior line of therapy and are ineligible for or relapsed after autologous stem cell transplantation (SCT). Pts with active autoimmune disease, CNS involvement, prior allogeneic SCT or chronic steroid use are excluded. Treatment comprises external beam RT to target site(s) daily for 5 days (Fig 1). Durvalumab 1500mg IV commences on day 2 of RT and continues 4-weekly until disease progression. Pts can continue until a second radiological progression if clinical benefit is ongoing. The primary endpoint is the toxicity, drug pharmacokinetics, maximum tolerated dose (MTD) and recommended phase two dose (RP2D) of simultaneous RT plus durvalumab. Secondary endpoints are response rates; progression free survival; and overall survival. An exploratory PET substudy will employ novel tracers to characterise the local and systemic immune response via assessment of the biodistribution of durvalumab (with 89Zr-Durvalumab) and CD8+ T cells (with 89Zr -Df-IAB22M2C). Biomarker sample collection is synchronised with PET response assessment. A comprehensive translational substudy will apply high throughput technologies to tissue and sequential blood samples to characterise the tumour-immune system interaction and correlate novel host, tumour and tumour microenvironment factors with treatment responses and toxicity. Findings may inform the RP2D. RT dose and site escalation will proceed according to a 3+3 design with 5 dose levels (cohorts 1-5, Fig 2). The dose limiting toxicity assessment window is the first 28 days. Projected enrolment for determination of MTD and RP2D is 6-30 pts pending toxicity. Recruitment will continue to a total of 36 pts to allow for secondary endpoint analysis. 5 pts have been enrolled to date. Acknowledgements: Victorian Cancer Agency (funding), Astra Zeneca (durvalumab and funding), Celgene (funding), Imaginab (89Zr -Df-IAB22M2C)

Utility of 18F-FDG PET Response Assessment for Predicting Histopathologic Response to Chemoradiation in Squamous Cell Carcinoma of the Esophagus

Utility of 18F-FDG PET Response Assessment for Predicting Histopathologic Response to Chemoradiation in Squamous Cell Carcinoma of the Esophagus

Pembrolizumab in Combination with Standard RCHOP Therapy for Previously Untreated Diffuse Large B-Cell Lymphoma

Pembrolizumab in Combination with Standard RCHOP Therapy for Previously Untreated Diffuse Large B-Cell Lymphoma

FDG PET in response evaluation of bulky masses in paediatric Hodgkin’s lymphoma (HL) patients enrolled in the Italian AIEOP-LH2004 trial

We present the results of an investigation of the role of FDG PET in response evaluation of bulky masses in paediatric patients with Hodgkin's lymphoma (HL) enrolled in the Italian AIEOP-LH2004 trial. We analysed data derived from 703 patients (388 male, 315 female; mean age 13years) with HL and enrolled in 41 different Italian centres from March 2004 to September 2012, all treated with the AIEOP-LH2004 protocol. The cohort comprised 309 patients with a bulky mass, of whom 263 were evaluated with FDG PET at baseline and after fourcycles of chemotherapy. Responses were determined according to combined functional and morphological criteria. Patients were followed up for a mean period of 43months and for each child we calculated time-to-progression (TTP) and relapse rates considering clinical monitoring, and instrumental and histological data as the reference standard. Statistical analyses were performed for FDG PET and morphological responses with respect to TTP. Multivariate analysis was used to define independent predictive factors. Overall, response evaluation revealed 238 PET-negative patients (90.5%) and 25 PET-positive patients (9.5%), with a significant difference in TTP between these groups (mean TTP: 32.67months for negative scans, 23.8months for positive scans; p < 0.0001, log-rank test). In the same cohort, computed tomography showed a complete response (CR) in 85 patients (32.3%), progressive disease (PD) in 6 patients (2.3%), and a partial response (PR) in 165 patients (62.7%), with a significant difference in TTP between patients with CR and patients with PD (31.1months and 7.9months, respectively; p < 0.001, log-rank test). Similarly, there was a significant difference in relapse rates between PET-positive and PET-negative patients (p = 0000). In patients with PR, there was also a significant difference in TTP between PET-positive and PET-negative patients (24.6months and 34.9months, respectively; p < 0.0001). In the multivariate analysis with correction for multiple testing, only the PET result was an independent predictive factor in both the entire cohort of patients and the subgroup showing PR on CT (p< 0.01). After fourcycles of chemotherapy, FDG PET response assessment in paediatric HL patients with a bulky mass is a good predictor of TTP and disease outcome. Moreover, in patients with a PR on CT, PET was able to differentiate those with a longer TTP. In paediatric HL patients with a bulky mass and in patients with a PR on CT, response on FDG PET was an independent predictive factor.

Preliminary Results of FDG-PET Scanning after GDP Chemotherapy Prior to Autologous Stem Cell Transplant (ASCT) for Relapsed/Refractory (RR) Lymphoma

Introduction:Gemcitabine, dexamethasone and cisplatin (GDP) has become a standard salvage chemotherapy (SC) regimen for relapsed/refractory (RR) lymphoma prior to autologous stem cell transplantation (ASCT) (Crump JCO 2014). Response to SC is now evaluated using 18-Fluoro-deoxyglucose positron-emission-tomography (FDG-PET) scans based on the recent Lugano classification (Cheson JCO 2014). We evaluated the response of patients (pts) with Hodgkin lymphoma (HL) and aggressive non-Hodgkin lymphoma (NHL) to GDP by PET-CT scans and attempted to determine whether PET was predictive of outcome.Methods:We performed a retrospective chart review of consecutive HL and DLBCL (diffuse large B-cell lymphoma) pts who underwent ASCT following GDP SC at our centre between January 2014 and July 2016. All pts previously received anthracycline-based chemotherapy (typically ABVD for HL or R-CHOP for NHL) for primary treatment. Pts underwent FDG-PET scans after 3 cycles of SC and scans were retrospectively reported with the Deauville Criteria Scale with Deauville scores of 1-3 considered negative, whereas scores of 4 or 5 represented a positive result. Response to GDP was documented with CT scans using 1999 Working group Criteria (JCO 1999). Pts proceeded to ASCT if they had a PR by CT imaging and no signs of PD on PET-CT. Post-PET radiation or additional chemotherapy could be given at the discretion of the treating physician. Progression free survival (PFS) and overall survival (OS) were calculated by the Kaplan-Meier method from the date of progression or date of ASCT. Statistical analysis to determine the significance of PET result on outcome was performed using the long rank test.Results: 45 pts with DLBCL and 29 pts with HL were identified: median age was 45 (range: 23-69) and 29 (range: 19-58) years respectively. Baseline patient characteristics are listed in Table 1. Following GDP SC, PET Deauville scores of 1-3 were reported in 55% of HL and 29% of DLBCL pts. Overall response rate to GDP by CT was 72% for HL pts and 64% for DLBCL pts (Table 2). For HL, 100% (16/16) of pts with a PET(-) scan and 91% (10/11) with a PET(+) result proceeded to ASCT. 85% (11/13) of DLBCL pts who had a PET(-) scan and 48% (15/31) with a PET(+) scan underwent ASCT. Additional therapy post PET scan included involved field radiation, additional chemotherapy (mini-BEAM) or novel therapy (brentuximab and bendamustine for HL patients). Median follow-up time was 14.2 months (HL) and 13.4 months (DLBCL) from relapse/progression after initial chemotherapy; and 9.6 months (HL) and 10.9 months (DLBCL) from ASCT. There was a statistically significant difference between PET(+) and PET(-) DLBCL patients from the time of initial disease progression for PFS (26% versus 69%, p=0.011) that did not reach statistical significance for OS (p=0.072). However, there was no significant difference for PFS and OS in DLCBL from ASCT when stratified by PET result (p= 0.154 and p=0.723 respectively). In HL pts, no statistically significant differences for PFS and OS from progression (p=0.480 and p=0.387 respectively) or from ASCT (p=0.579 and p=0.450 respectively) were found when stratified by PET result (see Tables 3 and 4).Conclusion: Deauville 4-5 PET scores appear to be predictive of PFS for RR-DLBCL pts. The lack of a significant difference between PET results for OS in DLBCL is likely due to sample size and the need for longer follow-up. For RR-HL pts, PFS and OS rates were both high but did not seem to noticeably differ by PET result. Additional therapy employed for Deauville 4-5 patients peri-ASCT could influence outcome. Overall, PET response assessment post GDP appears to stratify outcome in patients with DLBCL and PET adapted therapy in HL patients may improve outcome in Deauville 4-5 patients. Review of pending cases and subsequent follow-up is ongoing. [Display omitted] [Display omitted] [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

18F]FDG PET/CT-based response assessment of stage IV non-small cell lung cancer treated with paclitaxel-carboplatin-bevacizumab with or without nitroglycerin patches

PurposeNitroglycerin (NTG) is a vasodilating drug, which increases tumor blood flow and consequently decreases hypoxia. Therefore, changes in [18F] fluorodeoxyglucose positron emission tomography ([18F]FDG PET) uptake pattern may occur. In this analysis, we investigated the feasibility of [18F]FDG PET for response assessment to paclitaxel-carboplatin-bevacizumab (PCB) treatment with and without NTG patches. And we compared the [18F]FDG PET response assessment to RECIST response assessment and survival.MethodsA total of 223 stage IV non-small cell lung cancer (NSCLC) patients were included in a phase II study (NCT01171170) randomizing between PCB treatment with or without NTG patches. For 60 participating patients, a baseline and a second [18F]FDG PET/computed tomography (CT) scan, performed between day 22 and 24 after the start of treatment, were available. Tumor response was defined as a 30 % decrease in CT and PET parameters, and was compared to RECIST response at week 6. The predictive value of these assessments for progression free survival (PFS) and overall survival (OS) was assessed with and without NTG.ResultsA 30 % decrease in SUVpeak assessment identified more patients as responders compared to a 30 % decrease in CT diameter assessment (73 % vs. 18 %), however, this was not correlated to OS (SUVpeak30 p = 0.833; CTdiameter30 p = 0.557). Changes in PET parameters between the baseline and the second scan were not significantly different for the NTG group compared to the control group (p value range 0.159–0.634). The CT-based (part of the [18F]FDG PET/CT) parameters showed a significant difference between the baseline and the second scan for the NTG group compared to the control group (CT diameter decrease of 7 ± 23 % vs. 19 ± 14 %, p = 0.016, respectively).ConclusionsThe decrease in tumoral FDG uptake in advanced NSCLC patients treated with chemotherapy with and without NTG did not differ between both treatment arms. Early PET-based response assessment showed more tumor responders than CT-based response assessment (part of the [18F]FDG PET/CT); this was not correlated to survival. This might be due to timing of the [18F]FDG PET shortly after the bevacizumab infusion.

Current standards and new concepts in MRI and PET response assessment of antiangiogenic therapies in high-grade glioma patients.

Despite multimodal treatment, the prognosis of high-grade gliomas is grim. As tumor growth is critically dependent on new blood vessel formation, antiangiogenic treatment approaches offer an innovative treatment strategy. Bevacizumab, a humanized monoclonal antibody, has been in the spotlight of antiangiogenic approaches for several years. Currently, MRI including contrast-enhanced T1-weighted and T2/fluid-attenuated inversion recovery (FLAIR) images is routinely used to evaluate antiangiogenic treatment response (Response Assessment in Neuro-Oncology criteria). However, by restoring the blood-brain barrier, bevacizumab may reduce T1 contrast enhancement and T2/FLAIR hyperintensity, thereby obscuring the imaging-based detection of progression. The aim of this review is to highlight the recent role of imaging biomarkers from MR and PET imaging on measurement of disease progression and treatment effectiveness in antiangiogenic therapies. Based on the reviewed studies, multimodal imaging combining standard MRI with new physiological MRI techniques and metabolic PET imaging, in particular amino acid tracers, may have the ability to detect antiangiogenic drug susceptibility or resistance prior to morphological changes. As advances occur in the development of therapies that target specific biochemical or molecular pathways and alter tumor physiology in potentially predictable ways, the validation of physiological and metabolic imaging biomarkers will become increasingly important in the near future.

Baseline metabolic tumour volume is an independent prognostic factor in Hodgkin lymphoma.

The presence of a bulky tumour at staging in Hodgkin lymphoma (HL) is a predictor of a poor outcome. The total metabolic tumour volume at baseline (TMTV0) computed on PET may improve the evaluation of tumour burden. To explore the clinical usefulness of TMTV0, we compared the prognostic value of TMTV0, tumour bulk and interim PET response in a retrospective single-centre study. From 2007 to 2010, 59 consecutive patients with a first diagnosis of HL were treated in our institution. PET was done at baseline (PET0) and after two cycles of chemotherapy (PET2), and treatment was not modified according to the PET2 result. TMTV0 was measured with a semiautomatic method using a 41 % SUVmax threshold. SUVmax reduction between PET0 and PET2 (ΔSUVmaxPET0-2) was also computed. Based on ROC analysis, patients with a ΔSUVmaxPET0-2 >71 % were considered good responders and a TMTV0 >225 ml was considered to represent hypermetabolic bulky disease. Median TMTV0 was 117 ml and 17 patients (29 %) had a TMTV0 >225 ml. TMTV0 (>225 ml vs. ≤225 ml) and tumour bulk (<10 cm vs. ≥10 cm) were predictive of 4-year PFS: 42 % vs. 85 % (p = 0.001) and 44 % vs. 79 % (p < 0.03), respectively. In multivariate analysis, using ΔSUVmaxPET0-2, TMTV0 and bulky tumour as covariates, only ΔSUVmaxPET0-2 (p = 0.0005, RR 6.3) and TMTV0 (p < 0.006, RR 4.4) remained independent predictors of PFS. Three prognosis groups were thus identified: ΔSUVmaxPET0-2 >71 % and TMTV0 ≤225 ml (n = 37, 63 %), ΔSUVmaxPET0-2 = <71 % or TMTV0 >225 ml (n = 17, 29 %), and ΔSUVmaxPET0-2 = <71 % and TMTV0 >225 ml (n = 5, 8 %). In these three groups the 4-year PFS rates were 92 %, 49 %, and 20 % (p < 0.0001), respectively. TMTV0 is more relevant than tumour bulk for predicting the outcome in patients with HL, and adds a significant prognostic insight to interim PET response assessment. The combination of TMTV0 and ΔSUVmaxPET0-2 made it possible to identify three subsets of HL patients with different outcomes. This may guide clinicians in their choice of therapeutic strategy.

Effects of ROI Placement on PET-Based Assessment of Tumor Response to Therapy

Purpose. Quantitative PET response assessment during therapy requires regions of interest (ROI). Commonly, a fixed-size ROI is placed at the maximum uptake point in the pretreatment study. For intratreatment, the ROI is placed either at the maximum uptake point (ROIpeak) or at the same location as the pretreatment ROI (ROIsame). We have evaluated the effects of the ROI placement on response assessment. Methods. PET scans of 15 head and neck cancer patients were used to evaluate the effects of the two ROI methods on response assessment. Results. The average intratreatment ROIpeak uptake was 13.4% higher than the ROIsame uptake (range −14% to 38%). The average relative change in ROIpeak uptake was 7.9% lower than ROIsame uptake (range −5% to 36%), resulting in ambiguous tumour classification in 19% of the tumours. Conclusion. Quantitative PET response assessment using a fixed-size ROI is sensitive the ROI placement. The difference between ROIpeak and ROIsame could be substantial resulting in ambiguous response assessment. Although the fixed-size ROI is simple to implement, it is also prone to the limitations and should be used with caution. Clinical trial data are necessary to establish reliable thresholds for fixed-size ROI techniques and to evaluate their efficacy for response assessment.

Early FDG PET response assessment of preoperative radiochemotherapy in locally advanced rectal cancer: correlation with long-term outcome

The aim of the present study is to prospectively evaluate the prognostic value of previously defined [(18)F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG PET) criteria of early metabolic response in patients with locally advanced rectal cancer (LARC) after long-term follow-up. Forty-two patients with poor prognosis LARC underwent three biweekly courses of chemotherapy with oxaliplatin, raltitrexed and 5-fluorouracil modulated by levofolinic acid during pelvic radiotherapy. FDG PET studies were performed before and 12 days after the beginning of the chemoradiotherapy (CRT) treatment. Total mesorectal excision (TME) was carried out 8 weeks after completion of CRT. A previously identified cutoff value of ≥52 % reduction of the baseline mean FDG standardized uptake value (SUV(mean)) was applied to differentiate metabolic responders from non-responders and correlated to tumour regression grade (TRG) and survival. Twenty-two metabolic responders showed complete (TRG1) or subtotal tumour regression (TRG2) and demonstrated a statistically significantly higher 5-year relapse-free survival (RFS) compared with the 20 non-responders (86 vs 55 %, p = .014) who showed TRG3 and TRG4 pathologic responses. A multivariate analysis demonstrated that early ∆SUV(mean) was the only pre-surgical parameter correlated to the likelihood of recurrence (p = .05). This study is the first prospective long-term evaluation demonstrating that FDG PET is not only an early predictor of pathologic response but is also a valuable prognostic tool. Our results indicate the potential of FDG PET for optimizing multidisciplinary management of patients with LARC.

Positron Emission Tomography Status and Tandem High-Dose Therapy Favorably Influence Outcome of Patients with Relapsed and/or Refractory Hodgkin Lymphoma

Abstract 335The cure of relapsed or refractory Hodgkin Lymphoma (HL) still remains a challenge. High dose chemotherapy followed by autologous stem cell transplantation (ASCT) is the standard of care but almost half of patients relapse after ASCT and have poor outcome. Predictive factors including an interval from end of first line therapy to relapse shorter than 12 months, an Ann-Arbor stage III or IV at relapse, and relapse in previously irradiated field are currently used to identify patients with poor outcome. Development of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) assessment improves evaluation of response both in first line and salvage treatments. The aim of our study is first to confirm the predictive value of PET status before ASCT and then to compare ASCT strategy (single versus tandem) in patients with relapsed and/or refractory HL. We here report a series of 111 consecutive patients with relapsed and/or refractory HL who achieved at least partial remission (PR) at PET evaluation after one line of salvage chemotherapy and who underwent single or tandem ASCT. PET response assessment showed 85 (77%) patients in CR (PET- group) and 26 (23%) in PR (PET+ group). Five-year overall (OS) and progression free survival (PFS) were 81% and 64% respectively. There were significant differences in 5-year PFS (79% versus 23%, p<0.001) and 5-year OS (90% versus 55%, p=0.001) between PET- and PET+ groups respectively. This predictive value remained significant in both favorable/intermediate and unfavorable subgroups. In PET+ subgroup analysis, tandem ASCT dramatically improved 5-years PFS, from 0% to 43% (p=0.034) compared to single ASCT. Multivariate analysis showed that PET status (HR: 5.26 [2.57–10.73]) and tandem ASCT (HR: 0.39 [0.19–0.78]) but not relapse risk (HR: 1.77 [0.80–3.92]) significantly influenced PFS, while only PET status significantly influenced OS (HR: 4.03 [1.38–11.75]). Our results suggest that I) PET status before ASCT must be considered as a strong and significant prognostic factor influencing outcome and identifying high risk patients for more intensive strategy II) Tandem ASCT improved outcome compared to single ASCT, especially for PET+ patients. Disclosures:No relevant conflicts of interest to declare.

Positron emission tomography (PET) with 89Zr-labeled trastuzumab (89Zr-trastuzumab): Monitoring HER2 expression in HER2-positive gastric cancer in vivo.

35 Background: The ToGA study established HER2 is a target in the treatment of gastric cancer. Trastuzumab pharmacokinetics and organ distribution is varied in each patient and is heavily affected by the extent of tumor load (Oude Munnink, JCO 2010). 89Zr-trastuzumab HER2 PET can be used to image that variability and may aid in detection and staging of HER2-positive tumors. We are implementing 89Zr-radiolabeled trastuzumab PET in vivo for imaging of HER2-positive gastric cancer and for future non-invasive assessment of HER2 inhibition with a dual irreversible HER1/HER2 inhibitor, BIBW-2992. Methods: 89Zr (t1/2 = 3.17 days) was prepared via the 89Y(p,n)89Zr transmutation with high radiochemical yields (1.52±0.11 mCi/μAh) and purity (&gt;99.99%). Trastuzumab was functionalized with the tris-hydroxamate chelate, desferrioxamine B (DFO) and radiolabeled with [89Zr]Zr-oxalate at room temperature. 89Zr-trastuzumab PET experiments in athymic nu/nu mice bearing sub-cutaneous NCI-N87 (HER2+) and/or SNU1 (HER2-) tumors were conducted. NCI-N87 gastric cancer cells were treated with BIBW-2992. Results: 89Zr-trastuzumab radiolabeling proceeded in high radiochemical yield and specific-activity of 2.82±0.05 mCi/mg. In vitro assays demonstrated &gt;99% radiochemical purity with an immunoreactive fraction of 0.87±7. In vivo biodistribution experiments revealed high and specific uptake in HER2-positive tumors after 72 h (85.2±11.1% ID/g) with retention of activity for over 120 h. No uptake was seen in HER2-negative gastric cancer xenografts. In vitro, BIBW-2992 demonstrates dose dependent growth inhibition in the HER2+ gastric cancer cell line. Conclusions: 89Zr-trastuzumab provides quantitative and highly-specific delineation of HER2-positive gastric cancer. In vivo studies of BIBW2-2992 in gastric cancer with 89Zr-trastuzumab HER2 PET response assessment are underway. A Phase I study of 89Zr-trastuzumab PETin HER2-positive patients is to open at MSKCC imminently. No significant financial relationships to disclose.