Response-adapted consolidation therapy strategy for patients with metastatic high-risk neuroblastoma: Results of the SMC NB-2014 study.

BACKGROUND: Tandem high-dose chemotherapy and autologous stem cell transplantation (HDCT/auto-SCT) and incorporation of 131I-metaiodobenzylguanidine (131I-MIBG) treatment have shown positive outcomes in high-risk neuroblastoma. However, more optimized treatment strategies are still needed. PROCEDURE: The NB-2014 study was a nonrandomized, prospective trial that examined survival outcomes in metastatic high-risk neuroblastoma patients using response-adapted consolidation therapy. We used post-induction residual 123I-MIBG status at metastatic sites as a treatment response marker. Patients achieving complete resolution of MIBG uptake at metastatic sites underwent a reduced first HDCT/auto-SCT with a 20% dose reduction in HDCT. After the first HDCT/auto-SCT, patients with remaining MIBG uptake received dose-escalated (18 mCi/kg) 131I-MIBG treatment. In contrast, those with complete resolution of MIBG at metastatic sites received a standard dose (12 mCi/kg) of 131I-MIBG. We compared survival and toxicity outcomes with a historical control group from the NB-2009. RESULTS: Of 65 patients treated, 63% achieved complete resolution of MIBG uptake at metastatic sites following induction chemotherapy, while 29% of patients still had MIBG uptake at metastatic sites after the first HDCT/auto-SCT. The 3-year event-free survival (EFS) and overall survival (OS) rates were 68.2% ± 6.0% and 86.5% ± 4.5%, respectively. Compared to NB-2009, EFS was similar (p = .855); however, NB-2014 had a higher OS (p = .031), a lower cumulative incidence of treatment-related mortality (p = .036), and fewer acute and late toxicities. CONCLUSIONS: Our results suggest that response-adaptive consolidation therapy based on chemotherapy response at metastatic sites facilitates better treatment tailoring, and appears promising for patients with metastatic high-risk neuroblastoma.

The role of response adapted therapy in the era of novel agents.

The optimal treatment of classic Hodgkin Lymphoma (cHL) requires an individualized approach, with therapy guided by pretreatment clinical risk stratification and interim response assessment with positron emission tomography (PET). The overall goal is to achieve high cure rates while minimizing acute toxicity and late therapy-related effects. Interim PET-adapted strategies (iPET) were initially developed with traditional chemotherapy, reducing intensity after interim complete response and escalating treatment for patients with iPET+ disease. Recently, novel agents including brentuximab vedotin and the checkpoint inhibitor immunotherapies (CPIs) pembrolizumab and nivolumab have been adopted into the front-line treatment of cHL, and PET-adapted approaches may be relevant for these drugs as well. In this review we discuss response-adapted strategies utilizing novel agents, consider challenges including indeterminate radiographic findings with CPIs, and address emerging techniques for response assessment including new PET-based imaging metrics and the role of circulating tumor DNA.

Real-life study on the use of response adapted therapy in patients with Hodgkin Lymphoma: Results from a multicenter experience.

Few data are known regarding the use of interim positron emission tomography (iPET) after the first two cycles (iPET2) of chemotherapy in treatment-naïve classical Hodgkin lymphoma (cHL) in routine clinical practice, and about the real-life adoption of intensification strategies for iPET positive patients. We conducted a multicenter retrospective study on cHL to investigate the use of iPET in the real-life setting, its prognostic role and outcomes of patients early shifted to intensification. Six hundreds and forty-one patients were enrolled (62% had advanced stage). iPET2 was positive in 89 patients (14%) including 8.7% and 17% early and advanced stage patients, respectively (p = 0.003). Among iPET 2 positive cases treatment was immediately modified in 19 cases; in 14 cases treatment was modified after an additional positive iPET4. Overall 56 iPET2 positive patients never received intensified therapies. Most frequently used intensified therapy was autologous stem cell transplantation followed by BEACOPP. After a median follow-up of 72 months, the 5-year progression-free survival (PFS) was 82% with iPET2 positive patients showing a worse PFS compared with iPET2 negative cases: 31% versus 85%. Focusing on advanced stage patients with a positive iPET2, the 5-year PFS was 59% for patients shifted to intensified therapy at any time point versus 61% for patients who never received intensified therapy. Our study confirmed the higher curability of naïve cHL patients in a real-world setting, and the prognostic role of iPET2 in this setting. A poor adherence to response-adapted strategy which however did not translate into a difference in patient outcomes.

Measurable Residual Disease Monitoring in Lymphoma.

PURPOSE OF REVIEW: The utility of analyzing circulating tumor DNA (ctDNA), circulating tumor cells (CTCs), and disease in the bone marrow as an adjunctive tool in caring for hematologic cancer patients is expanding. This holds true for lymphoma where these biomarkers are being explored as a means of genotyping and quantifying disease. Regarding the latter, they can be used to monitor measurable residual disease (MRD) during and after treatment. This holds potential for aiding clinical decisions amidst treatment, detecting earlier relapse, and improving prognostication. Here, we review the evidence to support these applications in a variety of lymphoma subtypes. RECENT FINDINGS: Numerous clinical trials across a variety of lymphomas have demonstrated value in MRD monitoring. MRD monitoring is often prognostic for progression free survival (PFS) and even overall survival (OS) at several time points in a disease course, particularly when utilizing serial measurements. With regards to tailoring treatment, there are a growing number of trials examining MRD-adaptive treatment strategies to intensify or de-escalate treatment to individualize care. Lastly, MRD monitoring has been utilized successfully in detecting earlier relapse when compared to more standard methods of clinical surveillance such as radiographic assessment. Although not routinely implemented into clinical practice, MRD monitoring in lymphoma is helping shape the future landscape of this disease by aiding in prognostication, guiding therapy, and detecting earlier relapse. Steps to standardize and further examine this technology prospectively are being taken to bring MRD monitoring to the forefront of the field.

Cost-effectiveness of response-adapted therapy (RAT) for advanced Hodgkin's Lymphoma compared with conventional treatment in India: a Markov-model based analysis.

Cost effectiveness analysis of interim positron emission tomography (PET-2, done after 2 cycles of chemotherapy) based response adaptive therapy (RAT) approaches in advanced Hodgkin lymphoma (aHL) are not available from an Indian perspective. We used a five-year decision analytics model to assess the cost-effectiveness of the two RAT approaches [(escalation (RAT-1) or de-escalation (RAT-2)] compared with standard care (SOC) in aHL (mean age:35 years). Modelling data was derived from secondary sources and sensitivity analyses were performed to assess the robustness of the model. Net monetary benefit (NMB) gained from RAT2 in Indian rupees (INR) (INR 2,26,896) was higher than the RAT1 (INR 1,83,138) when compared with SOC. Proportion achieving the complete response after initial treatment (CR1) was the key determining factor for the RAT1/2 dominance over SOC. Despite higher initial input costs, response-adapted therapy of aHL was cost-effective by minimizing the cost incurred and disutility experienced during relapse and salvage.

Despite higher initial costs, response-adapted therapy based on the interim PET scan after 2 cycles of chemotherapy was more cost-effective when compared to standard therapy with 6 cycles of ABVD in patients with advanced Hodgkin's lymphoma. Among the RAT approaches, de-escalation (RAT-2) had better cost-effectiveness than the escalation approach (RAT-1).

[Classic Hodgkin lymphoma].

Classic Hodgkin lymphoma (cHL) is one of the common subtypes of malignant lymphoma in Western countries. Although patients with HL showed unsatisfactory results in the 1960s, the clinical development in radiotherapy and chemotherapy based on several clinical trials over the last 50 years has made cHL a curable disease with a favorable outcome. As a result, late-onset treatment-related toxicities such as second primary malignancies and cardiac events are thought to be a significant issue especially in early-stage patients. To minimize the toxic effects while maximizing the antitumor efficacy, several clinical trials to evaluate response-adapted strategies using interim PET scans and novel agents, such as brentuximab vedotin (BV) and/or immune checkpoint inhibitor (ICI) are currently underway. In this review, the author summarizes currently available data on PET-adapted and BV and/or ICI-containing therapies for untreated cHL, and discusses their future prospects in cHL treatment.

Response-Adapted Therapy for Newly Diagnosed Multiple Myeloma.

PURPOSE OF REVIEW: The development of potent novel agents has improved outcomes for patients with multiple myeloma (MM). Heterogeneity of response to therapy, an expanding arsenal of treatment options, and cost are however major challenges for physicians making treatment decisions. Response-adapted therapy is hence an attractive strategy for sequencing of therapy in MM. Despite its successful application in other haematologic malignancies, response-adapted therapy is yet to become a standard of care for MM. We provide our perspective on response-adapted therapeutic strategies evaluated thus far and how they may be implemented and improved on in treatment algorithms of the future. RECENT FINDINGS: While older studies suggested that early response based on International Myeloma Working Group response criteria could impact long-term outcomes, recent data have contradicted these findings. The advent of minimal residual disease (MRD) as a powerful prognostic factor in MM has raised the promise of MRD-adapted treatment strategies. The development of more sensitive techniques for paraprotein quantification as well as imaging modalities to detect extramedullary disease is likely to change response assessment in MM. These techniques combined with MRD assessment may provide sensitive and holistic response assessments which could be evaluated in clinical trials. Response-adapted treatment algorithms have the potential to allow an individualised treatment strategy, maximising efficacy, while minimising toxicities and cost. Standardisation of MRD methodology, incorporation of imaging into response assessment, and the optimal management of MRD positive patients are key questions to be addressed in future trials.

Continuous induction with lenalidomide/dexamethasone versus autologous stem cell transplantation in newly diagnosed multiple myeloma: a case for response-adapted approach.

Although upfront autologous stem cell transplantation (ASCT) generally improves progression-free survival (PFS) in newly diagnosed multiple myeloma (NDMM), the overall survival (OS) benefit and optimal timing of ASCT are not well established. Patients with early response may be able to safely continue induction and avoid ASCT without compromised outcomes. We report an extended follow-up analysis of a phase 2 trial that randomized transplant-eligible patients with NDMM who responded to induction (50/65 patients) to continued induction or ASCT; median follow-up was 8.0 years. Patients had similar 8-year PFS (55% vs. 43%), 8-year OS (83% vs. 72%), and rates of at least very good partial response (72% vs. 84%) whether continuing induction of lenalidomide and dexamethasone (Ld arm) or receiving ASCT (Ld + ASCT arm) (p = 0.5). Notably, over 50% of patients receiving continuous Ld had PFS of 5-10 years. These results suggest the need for prospective trials incorporating response-adapted therapeutic approaches to NDMM.STATEMENT OF PRIOR PRESENTATIONPresented in abstract form (interim analysis) at the 56th annual meeting of the American Society of Hematology (San Francisco, CA, 6 December 2014) and at the 57th annual meeting of the American Society of Hematology (Orlando, FL, 3 December 2015).

Multicenter, phase II study of response-adapted lenalidomide-based therapy for transplant-ineligible patients with newly diagnosed multiple myeloma without high-risk features.

Lenalidomide and low-dose dexamethasone (Rd) are a standard treatment for older adults with multiple myeloma (MM). Lenalidomide monotherapy has rarely been evaluated for newly diagnosed transplant-ineligible MM patients. This multicenter phase II trial evaluated a response-adapted strategy for elderly patients with newly diagnosed MM without high-risk features. Patients were administered single-agent lenalidomide for the first 21 days of two 28-day cycles. Patients with progressive disease received Rd. The primary endpoint was progression-free survival using the uniform response assessment from the International Myeloma Working Group . Of the 34 enrolled patients, 28 were included in the efficacy analysis. The overall response rate (ORR, ≥ partial response [PR]) to single-agent lenalidomide or lenalidomide plus prednisone was 64.3%. Ten patients received Rd after disease progression, with an Rd ORR of 70%. The ORR of response-adapted lenalidomide-based therapy was 75%. After the median follow-up of 35.6 months, the median progression-free survival was 33.5 months (95% confidence interval [CI], 16.9-50.2), and the median overall survival was 51.8 months (95% CI, 22.0-81.6). The most common adverse event was neutropenia (46.7%), and 17 patients (56.7%) experienced infection including pneumonia. Response-adapted lenalidomide-based therapy was feasible in newly diagnosed, transplant-ineligible MM patients without high-risk features.

Positron emission tomography/computed tomography in the management of Hodgkin and B-cell non-Hodgkin lymphoma: An update.

18 F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) is now an integral part of lymphoma staging and management. Because of its greater accuracy compared with CT alone, PET/CT is currently routinely performed for staging and for response assessment at the end of treatment in the vast majority of FDG-avid lymphomas and is the cornerstone of response classification for these lymphomas according to the Lugano classification. Interim PET/CT, typically performed after 2 to 4 of 6 to 8 chemotherapy/chemoimmunotherapy cycles with or without radiation, is commonly performed for prognostication and potential treatment escalation or de-escalation early in the course of therapy, a concept known as response-adapted or risk-adapted treatment. Quantitative PET is an area of growing interest. Metrics, such as the standardized uptake value, changes (Δ) in the standardized uptake value, metabolic tumor volume, and total lesion glycolysis, are being investigated as more reproducible and potentially more accurate predictors of response and prognosis. Despite the progress made in standardizing the use of PET/CT in lymphoma, challenges remain, particularly with respect to its limited positive predictive value, emphasizing the need for more specific molecular probes. This review highlights the most relevant applications of PET/CT in Hodgkin and B-cell non-Hodgkin lymphoma, its strengths and limitations, as well as recent efforts at implementing PET/CT-based metrics as promising tools for precision medicine.

Advanced Hodgkin lymphoma in the East of England: a 10-year comparative analysis of outcomes for real-world patients treated with ABVD or escalated-BEACOPP, aged less than 60 years, compared with 5-year extended follow-up from the RATHL trial.

Treatment with ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine) or escalated(e)-BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisolone) remains the international standard of care for advanced-stage classical Hodgkin lymphoma (HL). We performed a retrospective, multicentre analysis of 221 non-trial ("real-world") patients, aged 16-59 years, diagnosed with advanced-stage HL in the Anglia Cancer Network between 2004 and 2014, treated with ABVD or eBEACOPP, and compared outcomes with 1088 patients in the Response-Adjusted Therapy for Advanced Hodgkin Lymphoma (RATHL) trial, aged 18-59 years, with median follow-up of 87.0 and 69.5 months, respectively. Real-world ABVD patients (n=177) had highly similar 5-year progression-free survival (PFS) and overall survival (OS) compared with RATHL (PFS 79.2% vs 81.4%; OS 92.9% vs 95.2%), despite interim positron-emission tomography-computed tomography (PET/CT)-guided dose-escalation being predominantly restricted to trial patients. Real-world eBEACOPP patients (n=44) had superior PFS (95.5%) compared with real-world ABVD (HR 0.20, p=0.027) and RATHL (HR 0.21, p=0.015), and superior OS for higher-risk (international prognostic score ≥3 [IPS 3+]) patients compared with real-world IPS 3+ ABVD (100% vs 84.5%, p=0.045), but not IPS 3+ RATHL patients. Our data support a PFS, but not OS, advantage for patients with advanced-stage HL treated with eBEACOPP compared with ABVD and suggest higher-risk patients may benefit disproportionately from more intensive therapy. However, increased access to effective salvage therapies might minimise any OS benefit from reduced relapse rates after frontline therapy.

Risk and Response-Adapted Treatment in Multiple Myeloma.

Myeloma therapeutic strategies have been adapted to patients' age and comorbidities for a long time. However, although cytogenetics and clinical presentations (plasmablastic cytology; extramedullary disease) are major prognostic factors, until recently, all patients received the same treatment whatever their initial risk. No strong evidence allows us to use a personalized treatment according to one cytogenetic abnormality in newly diagnosed myeloma. Retrospective studies showed a benefit of a double autologous transplant in high-risk cytogenetics according to the International Myeloma Working Group definition (t(4;14), t(14;16) or del(17p)). Moreover, this definition has to be updated since other independent abnormalities, namely gain 1q, del(1p32), and trisomies 5 or 21, as well as TP53 mutations, are also prognostic. Another very strong predictive tool is the response to treatment assessed by the evaluation of minimal residual disease (MRD). We are convinced that the time has come to use it to adapt the strategy to a dynamic risk. Many trials are ongoing to answer many questions: when and how should we adapt the therapy, its intensity and duration. Nevertheless, we also have to take into account the clinical outcome for one patient, especially adverse events affecting his or her quality of life and his or her preferences for continuous/fixed duration treatment.

Response-adapted therapy for the treatment of children with newly diagnosed high risk Hodgkin lymphoma (AHOD0831): a report from the Children's Oncology Group.

The AHOD0831 study for paediatric patients with high risk Hodgkin lymphoma tested a response-based approach designed to limit cumulative alkylator exposure and reduce radiation volumes. Patients (Stage IIIB/IVB) received two cycles of ABVE-PC (doxorubicin, bleomycin, vincristine, etoposide, prednisone, cyclophosphamide). Rapid early responders [RER, no positron emission tomography (PET) activity above mediastinal blood pool] were consolidated with 2 cycles of ABVE-PC. Slow early responders (SER) received 2 cycles of ifosfamide/vinorelbine and 2 cycles of ABVE-PC. Radiotherapy was administered to sites of initial bulk and/or SER. By intent-to-treat analysis, 4-year second event-free survival (EFS; freedom from second relapse or malignancy) was 91·9% [95% confidence interval (CI): 86·1-95·3%], below the projected baseline of 95% (P = 0·038). Five-year first EFS and overall survival (OS) rates are 79·1% (95% CI: 71·5-84·8%) and 95% (95% CI: 88·8-97·8%). Eight of 11 SER patients with persistent PET positive lesions at the end of chemotherapy had clinical evidence of active disease (3 biopsy-proven, 5 with progressive disease or later relapses). Although this response-directed approach did not reach the ambitiously high pre-specified target for second EFS, EFS and OS rates are comparable with results of recent trials despite the reduction in radiotherapy volumes from historical involved fields. Persistent PET at end of chemotherapy identifies a cohort at an especially high risk for relapse/early progression.

Response-Adapted Treatment Strategies in Hodgkin Lymphoma Using PET Imaging.

Hodgkin lymphoma, a B-cell malignancy, is most common in patients younger than 55 years. Between 70% and 90% are cured with standard approaches. The high cure rate and long-term survival resulted in a need to minimize therapy toxicity. Response-adapted approaches have been developed to de-escalate therapy in those likely to be cured and intensifying therapy in those not responding to initial treatment. FDG-PET after chemotherapy is highly predictive of outcome. Thus, FDG-PET has been incorporated into response-adapted treatments. Use of FDG-PET to guide treatment in Hodgkin lymphoma has been recommended. We summarize literature and discuss challenges and future directions.

Current treatment paradigms for advanced stage Hodgkin lymphoma.

The treatment of advanced classical Hodgkin Lymphoma (cHL) has evolved over the last 50 years with a progressive improvement in long term cure rates in patients up to the age of 60 years. However, a minority of these survivors experience severe morbidity and mortality resulting from intensive chemotherapy and radiotherapy, leading to a drive to de-escalate treatment without compromising survival. The early identification of patients with chemoresistant disease by functional imaging allows the modulation of therapy and an efficient means to test new agents in those most in need of more effective therapy. The outcomes of treatment for older patients have not improved at the same rate, and this group requires a different approach, incorporating specialist geriatric support to personalise therapy. Clinical trials that focus on quality of life, comorbidity and survival are needed to improve survival rates for this expanding population with complex needs.

Lenalidomide-based response-adapted therapy for older adults without high risk myeloma.

Combined lenalidomide and dexamethasone is a standard-of-care therapy for the treatment of older adults with multiple myeloma. Lenalidomide monotherapy has not been evaluated in newly diagnosed myeloma patients. We conducted a phase II study, evaluating a response-adapted therapy for older adults newly diagnosed with multiple myeloma without high-risk features who were ineligible for high-dose therapy and stem cell transplant. Patients were started on single-agent lenalidomide, and low-dose dexamethasone was added in the event of progressive disease, in a response-adapted approach. The primary endpoint was progression-free survival (PFS), and the International Myeloma Working Group's uniform response criteria were used to assess response and progression. Twenty-seven patients were enrolled, and 20 (74%) experienced a partial response or better to this response-adapted therapy. After a median follow-up of 69 months, the median PFS was 36 months [95% confidence interval (CI), 29·8 to not reached], and the median overall survival was 65 months (95% CI, 35·3 to not reached). Grade 3/4 adverse events were mainly haematological in nature. This response-adapted therapy in this patient population is feasible and results in durable responses that compare favourably with concurrent lenalidomide and dexamethasone. These results should be validated in prospective studies.

Significance of treatment response when managing patients with primary central nervous system lymphoma.

The precise role of radiation therapy in primary central nervous system lymphoma (PCNSL) remains controversial. We reviewed the records of all patients treated for PCNSL at our center between 2004 and 2015. A total of 103 patients treated with either chemotherapy alone (n = 30), radiotherapy alone (n = 36), or combined-modality treatment (n = 37) were analyzed. The median progression-free survival (PFS) and overall survival (OS) were 13.9 and 20.9 months, respectively. Of those who received chemotherapy, 52.2% achieved complete response/ unconfirmed complete response (CR/Cru) after induction; a trend for improved PFS was observed for those who received consolidation WBRT (NR vs. 30.1 months, p = .092) but not OS (NR vs. 31.6 months, p = .283). Patients who achieved a partial response with chemotherapy and proceeded with WBRT had a similar long-term survival to those who achieved CR/CRu with chemotherapy without WBRT (PFS 15.2 vs. 30.1 months, p = .888; OS 22.0 vs. 31.6 months, p = .340). Consolidation WBRT improved PFS, but not OS, and this must be balanced against possible risks of neurotoxicity.

Interim Functional Imaging Is an Independent Predictor of Progression-free Survival in Advanced Classical Hodgkin Lymphoma - A Real-world Analysis.

BACKGROUND: Response-adapted therapy in advanced classical Hodgkin lymphoma (cHL) using interim functional imaging (IFI) is under active investigation. PATIENTS AND METHODS: We retrospectively examined patients with advanced cHL receiving 2 front-line regimens stratified by IFI results at our institution. Time to endpoint analysis was estimated using the method of Kaplan-Meier with log ranks. Cox regression modeling was computed for multivariable analysis. RESULTS: A total of 124 patients with advanced cHL with a median follow up of 40.9 months were included. A total of 84 (67.7%) received ABVD (doxorubicin, bleomycin, vinblastine, and dacarbazine), whereas the remaining 40 (32.3%) received ABVD/eBEACOPP (escalated bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone). A positive IFI was seen in 36 (29%) patients. The corresponding 3-year progression free survival (PFS) stratified by IFI was 81.7% (95% confidence interval [CI], 70.1%-88.8%) versus 48.3% (95% CI, 30.4%-64.1%) (P < .0001) for patients with negative or positive scan, respectively. Escalation to eBEACOPP from ABVD following a positive IFI resulted in a significantly higher 3-year PFS at 58.7% (95% CI, 0.3-0.79) versus 39.7% (95% CI, 0.18-0.61) respectively (P = .00015). Overall survival (OS) was similar across the groups (P = .44) irrespective of therapy received. At multivariable analysis, IFI was the only predictor of PFS with a hazard ratio of 4.6 (95% CI, 1.9-10.8; P = .0008) whereas therapy escalation had a hazard ratio of 0.66 (95% CI, 0.14-3.4; P = .62). CONCLUSION: IFI is an independent predictor of PFS in advanced cHL and can guide therapeutic decisions in the real world. Given the inferior outcome seen in patients with a positive IFI, novel approaches of therapy are warranted.

A multiobjective Bayesian networks approach for joint prediction of tumor local control and radiation pneumonitis in nonsmall-cell lung cancer (NSCLC) for response-adapted radiotherapy.

PURPOSE: Individualization of therapeutic outcomes in NSCLC radiotherapy is likely to be compromised by the lack of proper balance of biophysical factors affecting both tumor local control (LC) and side effects such as radiation pneumonitis (RP), which are likely to be intertwined. Here, we compare the performance of separate and joint outcomes predictions for response-adapted personalized treatment planning. METHODS: A total of 118 NSCLC patients treated on prospective protocols with 32 cases of local progression and 20 cases of RP grade 2 or higher (RP2) were studied. Sixty-eight patients with 297 features before and during radiotherapy were used for discovery and 50 patients were reserved for independent testing. A multiobjective Bayesian network (MO-BN) approach was developed to identify important features for joint LC/RP2 prediction using extended Markov blankets as inputs to develop a BN predictive structure. Cross-validation (CV) was used to guide the MO-BN structure learning. Area under the free-response receiver operating characteristic (AU-FROC) curve was used to evaluate joint prediction performance. RESULTS: Important features including single nucleotide polymorphisms (SNPs), micro RNAs, pretreatment cytokines, pretreatment PET radiomics together with lung and tumor gEUDs were selected and their biophysical inter-relationships with radiation outcomes (LC and RP2) were identified in a pretreatment MO-BN. The joint LC/RP2 prediction yielded an AU-FROC of 0.80 (95% CI: 0.70-0.86) upon internal CV. This improved to 0.85 (0.75-0.91) with additional two SNPs, changes in one cytokine and two radiomics PET image features through the course of radiotherapy in a during-treatment MO-BN. This MO-BN model outperformed combined single-objective Bayesian networks (SO-BNs) during-treatment [0.78 (0.67-0.84)]. AU-FROC values in the evaluation of the MO-BN and individual SO-BNs on the testing dataset were 0.77 and 0.68 for pretreatment, and 0.79 and 0.71 for during-treatment, respectively. CONCLUSIONS: MO-BNs can reveal possible biophysical cross-talks between competing radiotherapy clinical endpoints. The prediction is improved by providing additional during-treatment information. The developed MO-BNs can be an important component of decision support systems for personalized response-adapted radiotherapy.

18F-FDG PET Response of Skeletal (Bone Marrow and Bone) Involvement After Induction Chemotherapy in Pediatric Hodgkin Lymphoma: Are Specific Response Criteria Required?

To determine whether the current 18F-FDG PET response criterion for skeletal involvement in Hodgkin lymphoma (HL) is suitable, we performed a systematic evaluation of the different types of skeletal involvement and their response on PET after 2 cycles of chemotherapy (PET-2). A secondary objective was to observe the influence of the initial uptake intensity (measured as qPET) and initial metabolic tumor volume (MTV) of skeletal lesions on the PET-2 response. Methods: The initial PET scans of 1,068 pediatric HL patients from the EuroNet-PHL-C1 trial were evaluated for skeletal involvement by central review. Three types of skeletal lesions were distinguished: PET-only lesions (those detected on PET only), bone marrow (BM) lesions (as confirmed by MRI or BM biopsy), and bone lesions. qPET and MTV were calculated for each skeletal lesion. All PET-2 scans were assessed for residual tumor activity. The rates of complete metabolic response for skeletal and nodal involvement on PET-2 were compared. Results: Of the 1,068 patients, 139 (13%) showed skeletal involvement (44 PET-only, 32 BM, and 63 bone). Of the 139 patients with skeletal involvement, 101 (73%) became PET-2-negative in the skeleton and 94 (68%) became PET-2-negative in the lymph nodes. The highest number of PET-2-negative scans in the skeleton was 42 (95%) in the 44 PET-only patients, followed by 22 skeletal lesions (69%) in the 32 BM patients and 37 (59%) in the 63 bone patients. Lesions that became PET-2-negative showed a lower initial median qPET (2.74) and MTV (2 cm3) than lesions that remained PET-2-positive (3.84 and 7 cm3, respectively). Conclusion: In this study with pediatric HL patients, the complete response rate for skeletal involvement on PET-2 was similar to that for nodal involvement. Bone flare seemed to be irrelevant. Overall, the current skeletal PET response criterion-comparison with the local skeletal background-is well suited. The initial qPET and MTV of skeletal lesions were predictive of the PET-2 result. Higher values for both parameters were associated with a worse PET-2 response.