Utility of interim and end-of-treatment [18F]-fluorodeoxyglucose positron emission tomography–computed tomography in frontline therapy of patients with diffuse large B-cell lymphoma

Integration of PET in DLBCL

F-fluorodeoxyglucose positron emission tomography-computerized tomography (18FDG-PET/CT) is the gold-standard imaging modality for staging and response assessment for most lymphomas. This review focuses on the utility of 18FDG-PET/CT, and its role in staging, prognostication and response assessment in diffuse large B-cell lymphoma (DLBCL), including emerging possibilities for future use.

Four cycles of R-CHOP followed by two applications of rituximab based on negative interim PET/CT: an analysis of a prospective trial

Background

R-CHOP with or without radiotherapy is the standard treatment for limited-stage diffuse large B-cell lymphoma (DLBCL). To prevent overtreatment, we assessed whether four cycles of CHOP plus six applications of rituximab was adequate with negative interim PET/CT and the role of consolidation radiotherapy specifically for patients with Waldeyer’s ring DLBCL. One hundred and twenty-nine patients with limited-stage DLBCL were enrolled in this open-label, nonrandomized, single-arm, phase 2 clinical trial (NCT01804127).

Methods

All patients were initially treated with 4 cycles of R-CHOP and underwent interim PET/CT. Patients with negative PET/CT (Deauville scores 1–2) received 2 additional cycles of rituximab monotherapy, unless they had any risk factors (primary mediastinal large B-cell lymphoma, extranodal primary or bulky disease). Otherwise, patients received another 2 cycles of R-CHOP. Patients with partial response on interim PET/CT received another 4 cycles of R-CHOP. No radiotherapy was conducted in Waldeyer’s ring DLBCL patients with negative PET/CT. The primary endpoint was 3-year progression-free survival (PFS). Overall survival (OS) in this study was compared with those from a historical study (NCT 00854568159).

Results

One hundred fifteen interim PET/CT scans (89.1%) were negative after 4 cycles of R-CHOP. An elevated lactate dehydrogenase level was significantly associated with positive interim PET/CT (P < 0.05). A trend of inferior outcome was observed in patients with positive interim PET/CT in terms of 3-year PFS (78.6% vs. 91.9%, P = 0.24) and 3-year OS (85.7% vs. 95.6%, P = 0.16). There were no PFS or OS differences found between patients treated with 4R-CHOP+2R and those treated with 6R-CHOP from a historical control study. Patients with Waldeyer’s ring DLBCL and negative interim PET/CT achieved a 3-year PFS of 87.2% and a 3-year OS of 89.7%.

Conclusions

Our results suggested that for interim PET/CT-negative patients without risk factors, the extra 2 cycles of CHOP might be omitted, and radiotherapy might also be omitted in patients with Waldeyer’s ring DLBCL without compromising the efficacy. These results need to be confirmed in a randomized study.

Trial registration

clinicaltrials.gov, NCT 01804127. Date of first registration: 05/03/2013.

Long-term results of PET-guided radiation in patients with advanced-stage diffuse large B-cell lymphoma treated with R-CHOP

Consolidative radiation therapy (RT) for advanced-stage diffuse large B-cell lymphoma (DLBCL) remains controversial, with routine practice continuing to include RT in patients with initial bulky disease or residual masses. Positron emission tomography (PET)-computed tomography is a sensitive modality for detecting the presence of residual disease at the end of treatment (EOT). A PET-guided approach to selectively administering RT has been the policy in British Columbia since 2005. Patients with advanced-stage DLBCL diagnosed from 1 January 2005 to 1 March 2017 and treated with at least 6 cycles of R-CHOP (cyclophosphamide, doxorubicin, vincristine, and prednisolone plus rituximab), who underwent EOT PET, were included in this analysis. Those with complete metabolic response (PET-negative [PET-NEG]) were observed; those with PET-positive (PET-POS) scans were offered consolidative RT, when feasible. Of the patient records reviewed, 723 were identified, with median follow-up of 4.3 years: 517 (72%) were PET-NEG; 206 (28%) were PET-POS. Time to progression (TTP) and overall survival (OS) at 3 years were 83% vs 56% and 87% vs 64%, in patients with PET-NEG and PET-POS scans, respectively. PET-POS patients with nonprogressing disease treated with consolidative RT (109 and 206; 53%) had outcomes approaching those of PET-NEG patients, with 3-year estimates of 76% and 80% for TTP and OS. PET-NEG patients who had bulky disease (≥10 cm) at diagnosis had outcomes indistinguishable from those without bulk, despite the omission of RT. These data suggest that patients with advanced-stage DLBCL who are PET-NEG at EOT and receive no RT have excellent outcomes. 18F-fluorodeoxyglucose-PET can reliably guide selective administration of consolidative RT, even in patients with initially bulky disease.

Predictive value of baseline 18F-FDG PET/CT and interim treatment response for the prognosis of patients with diffuse large B-cell lymphoma receiving R-CHOP chemotherapy

The present study aimed to investigate the prognostic value of baseline ¹⁸F-FDG PET/CT quantitative parameters and interim treatment response, and to assess whether the combination of these could improve the predictive efficacy in patients with diffuse large B-cell lymphoma (DLBCL) receiving R-CHOP chemotherapy. PET/CT images and clinical data of 64 patients with DLBCL who had undergone ¹⁸F-FDG PET/CT scan before and after 3 or 4 cycles of R-CHOP chemotherapy were retrospectively reviewed. The quantitative parameters including standardized uptake value (SUV), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and maximum diameter of the maximum lesion (Dmax) were measured on baseline PET/CT images. Cox proportional hazards model was used to evaluate the influence of baseline PET/CT parameters, clinical indicators and interim treatment response on prognosis. Survival analysis was performed using Kaplan-Meier method. Receiver operating characteristic (ROC) curve analysis was performed to estimate the predictive efficacy of the combination of baseline PET/CT parameters and interim treatment response. Ann Arbor stage, International Prognostic Index (IPI), lactate dehydrogenase (LDH), necrosis, MTVmax, TLGmax, Dmax and interim treatment response showed association with 2-year progression-free survival (PFS, P<0.05). LDH, necrosis, MTVmax, MTVsum, TLGmax, TLGsum, Dmax and interim treatment response showed association with 2-year overall survival (OS, P<0.05). Ann Arbor stage, Dmax and interim treatment response were found to be independent predictors of 2-year PFS (P<0.05), while Dmax and interim treatment response were found to be independent predictors of 2-year OS (P<0.05). The PFS and OS curves of Dmax <5.7 cm group and Dmax ≥5.7 cm group, complete response (CR) group and non-CR group were significantly different, respectively (P<0.05). The baseline ¹⁸F-FDG PET/CT parameters and interim treatment response have important prognostic values in DLBCL patients who received R-CHOP chemotherapy. Combined application of Dmax and interim treatment response improved the predictive efficacy of 2-year PFS. It may be helpful to identify patients who are at high-risk of relapse and to guide early clinical intervention of these patients.

Re-defining Prognosis of Hematological Malignancies by Dynamic Response Assessment Methods: Lessons Learnt in Chronic Myeloid Leukemia, Hodgkin Lymphoma, Diffuse Large B Cell Lymphoma and Multiple Myeloma

Risk-stratification is an essential management tool in defining prognosis of haematological neoplasms, both from patient and physician perspective. We define a new prognostic term "Dynamic Response Assessment Method(s) (DRAM)" as "method(s) used for re-stratifying disease prognosis at fixed intervals during the treatment course". The risk stratification is done after a fixed duration of treatment or chemotherapy cycles using sensitive techniques. The information obtained then can be used for further therapeutic decisions and prognostication. Currently, there is enough evidence that response to treatment improves the prognostic value of baseline disease variables in the management of Chronic Myeloid Leukemia, Hodgkin lymphoma, Diffuse Large B cell Lymphoma, and Multiple Myeloma. Through this review, we discuss the current evidence based application of "DRAM" to guide therapeutic decisions in these malignancies. We also discuss how the results of "DRAM" can be incorporated for redefining prognosis and counselling the patients with these selected hematologic malignancies.

Risk stratification of diffuse large B-cell lymphoma with interim PET-CT based on different cutoff Deauville scores

We evaluated the usefulness of interim ¹⁸F-FDG PET/CT for risk stratification using different cutoff values of the Deauville 5-point scale (5-DS) in DLBCL patients treated with rituximab plus cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP). One hundred and fifty patients underwent interim (I-) and end of treatment (EOT-) PET/CT scans. Applying the conventional 5-DS cutoff value of scores 4 to 5 at interim, there was no significant difference in progression free survival (PFS) between I-PET negative and I-PET positive patients. In comparison, PFS was inferior in patients with a score of 5 on I-PET scan compared with those with a score in between 1 to 4 (28.6% vs. 78.7%, p < .0001), and positive predictive value (71.4%) was improved compared to that obtained using cutoff value of scores 4 to 5 (34.9%). Our study shows that a cutoff score of 5 at interim has an alternative clinical implication for identifying patients at a significant risk.

Utility of baseline, interim and end-of-treatment 18F-FDG PET/CT in extranodal natural killer/T-cell lymphoma patients treated with L-asparaginase/pegaspargase

Positron emission tomography-computed tomography (PET/CT) is widely used for initial staging and monitoring treatment responses in Hodgkin and diffuse large B-cell lymphoma. However, its prognostic value in extranodal natural killer (NK)/T-cell lymphoma (ENKL) remains unclear. Here, we conducted a retrospective study to determine the impact of PET/CT in ENKL. Fifty-two patients newly diagnosed with ENKL were enrolled. Baseline maximum standardized uptake values (SUVmax), whole-body metabolic tumor volume (WBMTV) and whole-body total lesion glycolysis (WBTLG) were recorded. Additionally, interim PET/CT (I-PET) and end-of-treatment PET/CT (E-PET) results were scored using a 5-point scale. Patients were divided into groups using baseline parameter cut-off values; significant differences were found in overall survival (OS) and progression-free survival (PFS) between the high and low WBMTV and WBTLG groups and in OS between the two SUVmax groups. Positive I-PET and E-PET results predicted inferior PFS and OS. A multivariate analysis showed that baseline WBTLG, I-PET and E-PET results were associated with PFS and OS, and baseline SUVmax was an independent predictor of OS. Thus, baseline WBTLG, I-PET and E-PET results are good predictors of PFS and OS in ENKL patients who received L-asparaginase/pegaspargase in their first-line treatment, and baseline SUVmax is a valuable tool for assessing OS.

Interim PET Scans in Diffuse Large B-Cell Lymphoma: Is It Ready for Prime Time?

Prognostication of patients with diffuse large B-cell lymphoma (DLBCL) has improved in the past decade with a variety of clinical, morphologic, molecular, and radiographic methods. Comparable to data on the value of interim positron emission tomography (I-PET) in Hodgkin lymphoma, several retrospective and prospective studies are attempting to assess the value of I-PET scanning in DLBCL patients. In this review, we briefly describe and analyze the various prognostic methods in DLBCL with specific focus on the value of I-PET scanning in this disease. This is a timely analysis, as tailoring therapies based on prognosis at diagnosis are becoming of increased investigational interest.

PET Scans for Staging and Restaging in Diffuse Large B-Cell and Follicular Lymphomas

Positron emission tomography (PET)-CT was recommended in updated international guidelines for staging/restaging of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma (FL). In FL, PET was previously regarded as a research application only. This review concentrates on new publications related to PET in these diseases. In DLBCL, PET appears appropriate for staging using prognostic indices established with CT and baseline PET parameters, e.g. metabolic tumour volume, are prognostic of outcome. Early complete metabolic response (CMR) predicts end-of-treatment CMR with excellent prognosis. Patients without CMR at interim should not have treatment altered, but have a worse prognosis, and patients with other high risk features may need closer monitoring. The end-of-treatment scan is confirmed as the standard for remission assessment using Deauville criteria, which are also predictive for patients undergoing ASCT. In FL, PET is more sensitive for staging than CT but misses bone marrow involvement. PET-CT identifies patients at risk of progression after induction chemotherapy better than CT.

Focal colorectal uptake in (18)FDG-PET/CT: maximum standard uptake value as a trigger in a semi-automated screening setting

BACKGROUND

Focal colorectal uptake in (18)FDG-PET/CT may be associated with a malignancy and can be quantified. This provides the basis for an automatic trigger threshold above which cases are flagged for colonoscopic evaluation and below which for individual assessment.

PURPOSE

To determine the lowest maximum standard uptake (SUVmax) in colorectal cancer that could be used as a threshold to trigger endoscopic evaluation and to evaluate whether the SUVmax needs to be further normalised to a priori known extrinsic factors.

METHODS

The SUVmax was measured in 54 colorectal carcinomas and correlated with gender, age, blood glucose level, injected activity, body mass index and time to scan using t test or correlation coefficients (Pearson or Spearman, according to distribution).

RESULTS

There was no correlation between SUVmax and any of the extrinsic factors mentioned above. The lowest SUVmax value was 5 [mean ± SD (range): 11.1 ± 4.8 (5.0-24.6)].

CONCLUSION

In contrast to most other screening techniques, semi-automation in colorectal screening seems possible with PET/CT. This opens the door for further study into the feasibility of automated screening. Independent from extrinsic factors, an SUVmax ≥5.0 in a focal colorectal uptake in (18)FDG-PET/CT should automatically trigger for endoscopic evaluation, if not contraindicated. Cases with SUVmax <5 should be assessed individually before referral for endoscopy. Thus, more interpretation time could be spent on those cases with a lower uptake and more ambiguous diagnosis.

Next-generation prognostic assessment for diffuse large B-cell lymphoma

Current standard of care therapy for diffuse large B-cell lymphoma (DLBCL) cures a majority of patients with additional benefit in salvage therapy and autologous stem cell transplant for patients who relapse. The next generation of prognostic models for DLBCL aims to more accurately stratify patients for novel therapies and risk-adapted treatment strategies. This review discusses the significance of host genetic and tumor genomic alterations seen in DLBCL, clinical and epidemiologic factors, and how each can be integrated into risk stratification algorithms. In the future, treatment prediction and prognostic model development and subsequent validation will require data from a large number of DLBCL patients to establish sufficient statistical power to correctly predict outcome. Novel modeling approaches can augment these efforts.