Diagnosis of bone marrow involvement in angioimmunoblastic T-cell lymphoma should be based on both [18F]FDG-PET/CT and bone marrow biopsy findings

OBJECTIVE

During the initial staging of certain lymphoma subtypes, 18 F-fluorodeoxyglucose positron emission tomography/computed tomography ([18F]FDG-PET/CT) has become an alternative to bone marrow biopsy (BMB) for detecting bone marrow (BM) involvement. However, whether [18F]FDG-PET/CT can accurately detect BM involvement in angioimmunoblastic T-cell lymphoma (AITL) remains unknown. Our study aimed to assess the diagnostic and prognostic capability of [18F]FDG-PET/CT for detecting BM involvement in AITL. Methods: This retrospective study included 84 individuals newly diagnosed with AITL who underwent baseline BMB and [18F]FDG-PET/CT. "BM involvement" was defined as one or both of the following: 1) angioimmunoblastic T-cells detected in the BM; or 2) initially heightened focal uptake having disappeared on follow-up [18F]FDG-PET/CT. The ability of [18F]FDG-PET/CT to detect BM cancerous lesions was respectively analyzed by BM involvement confirmed by BMB or the aforementioned definition as the reference standard. The patients' clinical characteristics and survival and prognostic outcomes were respectively analyzed.

RESULTS

Of the 84 participants, five (6.0%) displayed positive BMB and PET/BM results, 17 (20.2%) had BMB-positive but PET/BM-negative results, eight (9.5%) showed BMB-negative but PET/BM-positive outcomes, and 54 (64.3%) displayed negative BMB and PET/BM outcomes. Using pre-defined BM involvement as the reference standard, [18F]FDG-PET/CT exhibited a specificity of 100%, sensitivity of 40%, negative predictive value (NPV) of 75%, and positive predictive value (PPV) of 100%. In contrast, using BMB-detected BM involvement as reference, [18F]FDG-PET/CT exhibited a sensitivity, specificity, PPV, and NPV of 38.5%, 76.1%, 22.7%, and 87.1%, respectively. Among patients with PET/BM-positive and BMB-negative outcomes, 62.5% (5/8) underwent upstaging from III to IV. In 58.8% (10/17) of patients who were initially diagnosed with stage II/III disease based on the [18F]FDG-PET/CT results, repeat BMB resulted in upstaging to IV. PET/BM-negative patients had a higher 3-year progression-free survival rate (38.3% vs. 22.8%, p = 0.018) and 3-year overall survival rate (64.4% vs. 34.6%, p = 0.011) than PET/BM-positive patients.

CONCLUSION

In AITL patients, PET/BM-positive results may obviate the necessity for repeat BMB to ascertain confirm BM involvement. PET/BM-negative results do not definitively exclude BM involvement. The combined use of [18F]FDG-PET/CT and BMB can increase the diagnostic accuracy of BM involvement for AITL patients.

Bone marrow biopsy superiority over PET/CT in predicting progression-free survival in a homogeneously-treated cohort of diffuse large B-cell lymphoma

Several studies have reported uneven results when evaluating the prognostic value of bone marrow biopsy (BMB) and PET/CT as part of the staging of diffuse large B‐cell lymphoma (DLBCL). The heterogeneity of the inclusion criteria and not taking into account selection and collinearity biases in the analysis models might explain part of these discrepancies. To address this issue we have carried a retrospective multicenter study including 268 DLBCL patients with a BMB and a PET/CT available at diagnosis where we estimated both the prognosis impact and the diagnostic accuracy of each technique. Only patients treated with R‐CHOP/21 as first line (n = 203) were included in the survival analysis. With a median follow‐up of 25 months the estimated 3‐year progression‐free survival (PFS) and overall survival (OS) were 76.3% and 82.7% respectively. In a multivariate analysis designed to avoid a collinearity bias with IPI categories, BMB‐BMI [bone marrow involvement](+) (HR: 3.6) and ECOG PS > 1 (HR: 2.9) were independently associated with a shorter PFS and three factors, age >60 years old (HR: 2.4), ECOG PS >1 (HR: 2.4), and abnormally elevated B2‐microglobulin levels (HR: 2.2) were independently associated with a shorter OS. In our DLBCL cohort, treated with a uniform first‐line chemotherapy regimen, BMI by BMB complemented performance status in predicting those patients with a higher risk for relapse or progression. In this cohort BMI by PET/CT could not independently predict a shorter PFS and/or OS.

The PI3K pathway in B cell metabolism

B cell growth and proliferation is tightly regulated by signaling through the B cell receptor and by other membrane bound receptors responding to different cytokines. The PI3K signaling pathway has been shown to play a crucial role in B cell activation, differentiation and survival. Activated B cells undergo metabolic reprograming in response to changing energetic and biosynthetic demands. B cells also need to be able to coordinate metabolic activity and proliferation with nutrient availability. The PI3K signaling network has been implicated in regulating nutrient acquisition, utilization and biosynthesis, thus integrating receptor-mediated signaling with cell metabolism. In this review, we discuss the current knowledge about metabolic changes induced in activated B cells, strategies to adapt to metabolic stress and the role of PI3K signaling in these processes.

The role of bone marrow biopsy and FDG-PET/CT in identifying bone marrow infiltration in the initial diagnosis of high grade non-Hodgkin B-cell lymphoma and Hodgkin lymphoma. Accuracy in a multicenter series of 372 patients

Bone marrow infiltration (BMI), categorized as an extra-nodal site, affects stage and is associated with poor prognosis in newly diagnosed lymphoma patients. We have evaluated the accuracy of PET/CT and bone marrow biopsy (BMB) to assess BMI in 372 lymphoma patients [140 Hodgkin Lymphoma (HL) and 232 High Grade B-cell non-Hodgkin Lymphoma (HG B-NHL), among them 155 Diffuse Large B-Cell Lymphoma (DLCL)]. For HL cases, and taking into account PET/CT, sensitivity, negative predictive value (NPV) and accuracy were 96.7, 99.3, and 99.3% while those of BMB were 32.3, 83.8, and 85%, respectively. For HG B-NHL and considering PET/CT, sensitivity, NPV, and accuracy were 52.7, 81.7, and 84.1%, while those of BMB were 77.6, 90.2, and 90.7%, respectively. In the HG B-NHL group, 25 patients would have been under-staged without BMB. These results lead us to recommend PET/CT and the avoidance of BMB to assess BMI in HL. In the case of HG B-NHL, bone marrow status should be assessed firstly by means of PET/CT; only in either focal or diffuse PET/CT with low borderline SUV max values or in negative cases, should BMB be carried out afterwards. In the HG B-NHL setting and at the present moment, both techniques are complementary.

Phase IIa Trial of Trastuzumab Emtansine With Pertuzumab for Patients With Human Epidermal Growth Factor Receptor 2–Positive, Locally Advanced, or Metastatic Breast Cancer

Purpose

Our phase IIa study characterized the safety and efficacy of two human epidermal growth factor receptor 2 (HER2) –targeted agents, trastuzumab emtansine (T-DM1) and pertuzumab, in patients with HER2-positive metastatic breast cancer (MBC).

Patients and Methods

Patients with HER2-positive locally advanced breast cancer or MBC were treated with 3.6 mg/kg T-DM1 plus pertuzumab (840-mg loading dose, then 420 mg subsequently) once every 3 weeks. The primary efficacy end point was investigator-assessed objective response rate (ORR).

Results

Sixty-four patients (43 patients in the second-line or greater setting [advanced MBC]; 21 patients in the first-line setting [first-line MBC]) were enrolled. Patients with advanced MBC had received trastuzumab and a median of six prior nonhormonal treatments for MBC; 86% of first-line MBC patients had received trastuzumab in the (neo)adjuvant setting. The ORR was 41% overall, 33% in patients with advanced MBC, and 57% in first-line patients. Median progression-free survival was 6.6, 5.5, and 7.7 months, respectively. The most common adverse events were fatigue (61%), nausea (50%), and diarrhea (39%). The most frequent grade ≥ 3 adverse events were thrombocytopenia (13%), fatigue (11%), and liver enzyme elevations (increased ALT: 9%; increased AST: 9%). One patient had left ventricular ejection fraction of less than 40% after study drug discontinuation. Exploratory biomarker analyses demonstrated that patients with above-median tumor HER2 mRNA levels had a numerically higher ORR than patients with below-median levels (44% v 33%, respectively).

Conclusion

T-DM1 and pertuzumab can be combined at full doses with no unexpected toxicities. The preliminary efficacy in patients in the first-line and advanced MBC settings warrants further investigation.

PET scan integration in lymphoma management

SUMMARY Despite a marked improvement in lymphoma treatment outcome, current prognostic models, relying on a pretreatment set of static clinical variables, appear unable to support a risk-adapted therapeutic strategy. On the other hand, functional imaging with 18F-fluoro-2-deoxy-D-glucose (FDG)-PET proved to be a reliable tool to dynamically assess tumor FDG uptake changes during and after treatment. In this article we aim to review the prognostic value of FDG-PET in all the stages of Hodgkin’s and non-Hodgkin’s lymphoma management, without the intent to address the diagnostic value of PET or to replace available consensus guidelines. In particular we focused on two critical issues: the cost–effectiveness of PET in the overall strategy of lymphoma diagnosis and treatment; and ongoing clinical trials adopting an interim PET-based strategy to modulate treatment intensity based on PET results. Finally, new trends in multimodality imaging, as well as in new radiopharmaceutical tracers, are briefly reviewed.