Optimizing Outcomes in Primary Mediastinal B-cell Lymphoma

Interim results of the PML-16, PML-19 protocols for primary mediastinal large B-cell lymphoma therapy

Introduction. Primary mediastinal lymphoma (PML) is an aggressive lymphoid tumor treatment success of which is determined by induction therapy. To date, none of the standard chemotherapy regimens (CT) have demonstrated an advantage in efficacy. Intensive therapy programs are associated with high toxicity.

Aim — to evaluate the efficacy and toxicity of two pilot prospective treatment protocols PML-16 and PML-19 as well as the possibility of using the analysis of freely circulating tumor DNA (ctDNA) to assess MRD in patients with PML.

Materials and methods. From January 2016 to January 2022, 34 previously untreated PML patients were included in the study; average age — 32; stage > I — in 60 %; extramediastinal lesions — in 14.7 %; bulky disease — in 73.5 % of patients. Positron emission tomography combined with computed tomography (PET-CT) was performed; ctDNA was determined to assess the completeness of remission.

Results. Eighteen patients received treatment according to the PML-16 protocol (6 courses of chemotherapy; 2 blocks of RmNHL-BFM-90 + 4 courses of R-EPOCH). After the end of therapy, all 18 patients achieved PET-negative remission. The next 16 patients received treatment according to the PML-19 protocol (4 courses of chemotherapy; 2 blocks of R-mNHL-BFM-90 + 2 courses of R-EPOCH) in combination with lenalidomide. After the end of therapy, 9 (56 %) patients achieved PET-negative remission; 7 (44 %) retained pathological activity (D4–5 points). After 3 and 6 months 15 (94 %) patients achieved normalization of metabolic activity. Considering the high frequency of false-positive results in patients with PML, a ctDNA study was performed to determine the depth of remission in 15 patients. After the end of therapy, all 15 patients had complete elimination of ctDNA. Of these, 5 (33 %) remained PET-positive at the end of treatment. During further observation, after 3–6 months, in 4 patients the level of metabolic activity decreased to physiological without the use of consolidating therapy. After the end of therapy, one patient suffered the new coronavirus infection, COVID-19. A month later, residual formation of SUVmax 14.2 remained in the mediastinum. The patient is currently under observation. With a median follow-up of 36 months (9 to 76 months) all 34 patients are in remission.

Conclusion. The effectiveness of PML-16 made it possible to abandon the consolidation therapy and refuted the idea of the need for 6 courses of CT. The combination of programs based on the application of the principle of high-dose shortpulse induction of remission (R-mNHL-BFM-90) in combination with the prolonged administration of medium doses (R-EPOCH) was crucial in achieving a successful result. The inclusion of lenalidomide in the “PML-19” program made it possible to achieve complete remission in 100 % of cases after 4 courses. The possibility of using DNA analysis to assess MRD in patients with PML was shown.

Treatment and outcomes of primary mediastinal B cell lymphoma: a three-decade monocentric experience with 151 patients

Primary mediastinal B cell lymphoma is a rare entity and often should be promptly treated as a hematological emergency: The initial treatment decision is crucial for the management of this disease. An observational retrospective study was conducted with the aim to improve information on treatment and outcomes of primary mediastinal B cell lymphoma in real practice. After 12 cycles of MACOP-B regimen (methotrexate, doxorubicin, cyclophosphamide, vincristine, bleomycin , and prednisone) with or without rituximab, 120 patients out of 151 (79.5%) achieved a complete response and 12 (7.9%) a partial response leading to a global response of 87.4%. The 21-year overall survival is 82.6%; progression-free and disease-free survivals are 69.3% and 86.4%, respectively. Regarding the role of radiotherapy (RT), patients with a negative PET scan after MACOP-B did not undergo RT: One out of these 48 (2.1%) showed a relapse at 11 months. All relapsed/refractory patients who achieved a response with checkpoint inhibitors are still in continuous complete response with a median follow-up of 14 months. Data that we have gathered over a 30-year experience in the treatment of primary mediastinal B cell lymphoma patients clearly indicate that a third-generation chemotherapy regimen such as MACOP-B is feasible and easily deliverable on an outpatient basis. Regarding the unmet medical need of relapsed/refractory patients, new encouraging results occurred with the advent of the checkpoint inhibitors.

Lactate dehydrogenase levels and 18F-FDG PET/CT metrics differentiate between mediastinal Hodgkin's lymphoma and primary mediastinal B-cell lymphoma

PURPOSE

This study aims to investigate whether clinical, laboratory, and fluorine-18-fluorodeoxyglucose (F-FDG) PET/CT findings can discriminate between mediastinal Hodgkin's lymphoma and primary mediastinal B-cell lymphoma (PMBCL).

PATIENTS AND METHODS

This retrospective study included 56 patients (42 with mediastinal Hodgkin's lymphoma and 14 with PBMCL). Differences in clinical, laboratory, and F-FDG PET/CT metrics were assessed between Hodgkin's lymphoma and PMBCL.

RESULTS

Lactate dehydrogenase (LDH) and F-FDG PET/CT-based maximum tumor diameter, lesion-to-liver ratio maximum standardized uptake value (SUVmax), and lesion-to-liver ratio peak standardized uptake value (SUVpeak) were all significantly higher (P<0.001) in PMBCL than in Hodgkin's lymphoma, and PMBCL also significantly more frequently (P=0.001) exhibited necrosis on F-FDG PET/CT than Hodgkin's lymphoma. LDH, maximum tumor diameter, lesion-to-liver ratio SUVmax, and lesion-to-liver ratio SUVpeak yielded areas under the receiver operating characteristic curve of 0.968 [95% confidence interval (CI): 0.923-1.000], 0.866 (95% CI: 0.765-0.968), 0.875 (95% CI: 0.776-0.975), and 0.874 (95% CI: 0.771-0.976), respectively. LDH (with cutoff of 236 U/l) achieved sensitivity and specificity of 81.6 and 100%, respectively; maximum tumor diameter (with cutoff of 9.98 cm) achieved sensitivity and specificity of 87.2 and 78.3%, respectively; lesion-to-liver ratio SUVmax (with cutoff of 7.12) achieved sensitivity and specificity of 94.9 and 64.3%, respectively; lesion-to-liver ratio SUVpeak (with cutoff of 11.45) achieved sensitivity and specificity of 97.4 and 64.3%, respectively; and the presence of necrosis achieved sensitivity and specificity of 78.6 and 74.4%, respectively, in discriminating PMBCL from Hodgkin's lymphoma.

CONCLUSION

LDH levels and several F-FDG PET/CT findings (tumor size, presence of necrosis, and degree of F-FDG uptake) are helpful in discriminating mediastinal Hodgkin's lymphoma from PMBCL.

The treatment of primary mediastinal large B-cell lymphoma: a two decades monocentric experience with 98 patients

Background

The purpose of this study is to investigate the most suitable first-line approach and the best combination treatment for primary mediastinal large B-cell lymphoma (PMLBCL) as they have been matter of debate for at least two decades.

Methods

Our single centre experience in the treatment of 98 de novo PMLBCL patients over the last 20 years is reviewed. All patients received MACOP-B chemotherapy. Thirty-seven received both rituximab and mediastinal radiotherapy; 30 were irradiated after chemotherapy, although not receiving rituximab and 20 received rituximab without radiotherapy consolidation. Eleven patients received chemotherapy only.

Results

Sixty-one (62.2%) patients achieved a complete response after MACOP-B (with or without rituximab); among the 27 (27.6%) partial responders, 21 obtained a complete response after radiotherapy. At the end of their scheduled treatment, 82 patients (83.7%) had a complete and 6 a partial response (6.1%). Eleven patients relapsed within the first 2 years of follow-up. The 17-year overall survival is 72.0% (15 patients died); progression-free and disease-free survival are 67.6% and 88.4%, respectively. A statistically significant difference in overall and progression-free survival was noted among treatment groups, although no disease-free survival difference was documented.

Conclusions

Our data indicate that a third-generation regimen like MACOP-B could be considered a suitable first-line treatment. Mediastinal consolidation radiotherapy impacts on survival and complete response rates and remains a good strategy to convert partial into complete responses. Data suggest that radiotherapy may be avoided in patients obtaining a complete response after (immuno)chemotherapy, but this requires confirmation with further ad hoc studies.