Outcome and feasibility of radiotherapy bridging in large B-cell lymphoma patients receiving CD19 CAR T in the UK

Radiotherapy (RT) has potential synergistic effects with chimeric antigen receptor (CAR) T but is not widely used as bridging therapy due to logistical challenges and lack of standardised protocols. We analysed RT bridging in a multicentre national cohort of large B-cell lymphoma patients approved for 3L axicabtagene ciloleucel or tisagenlecleucel across 12 UK centres. Of 763 approved patients, 722 were leukapheresed, 717 had data available on bridging therapy. 169/717 (24%) received RT bridging, 129 as single modality and 40 as combined modality treatment (CMT). Of 169 patients, 65.7% had advanced stage, 36.9% bulky disease, 86.5% elevated LDH, 41.7% international prognostic index (IPI) ≥3 and 15.2% double/triple hit at the time of approval. Use of RT bridging varied from 11% to 32% between centres and increased over time. Vein-to-vein time and infusion rate did not differ between bridging modalities. RT-bridged patients had favourable outcomes with 1-year progression-free survival (PFS) of 56% for single modality and 47% for CMT (1-year PFS 43% for systemic bridging). This is the largest cohort of LBCL patients receiving RT bridging prior to CAR T reported to date. Our results show that RT bridging can be safely and effectively used even in advanced stage and high-risk disease, with low dropout rates and excellent outcomes.

Hypoxia Is Associated with Increased Immune Infiltrates and Both Anti-Tumour and Immune Suppressive Signalling in Muscle-Invasive Bladder Cancer

Hypoxia and a suppressive tumour microenvironment (TME) are both independent negative prognostic factors for muscle-invasive bladder cancer (MIBC) that contribute to treatment resistance. Hypoxia has been shown to induce an immune suppressive TME by recruiting myeloid cells that inhibit anti-tumour T cell responses. Recent transcriptomic analyses show hypoxia increases suppressive and anti-tumour immune signalling and infiltrates in bladder cancer. This study sought to investigate the relationship between hypoxia-inducible factor (HIF)-1 and -2, hypoxia, and immune signalling and infiltrates in MIBC. ChIP-seq was performed to identify HIF1α, HIF2α, and HIF1β binding in the genome of the MIBC cell line T24 cultured in 1% and 0.1% oxygen for 24 h. Microarray data from four MIBC cell lines (T24, J82, UMUC3, and HT1376) cultured under 1%, 0.2%, and 0.1% oxygen for 24 h were used. Differences in the immune contexture between high- and low-hypoxia tumours were investigated using in silico analyses of two bladder cancer cohorts (BCON and TCGA) filtered to only include MIBC cases. GO and GSEA were used with the R packages "limma" and "fgsea". Immune deconvolution was performed using ImSig and TIMER algorithms. RStudio was used for all analyses. Under hypoxia, HIF1α and HIF2α bound to ~11.5-13.5% and ~4.5-7.5% of immune-related genes, respectively (1-0.1% O₂). HIF1α and HIF2α both bound to genes associated with T cell activation and differentiation signalling pathways. HIF1α and HIF2α had distinct roles in immune-related signalling. HIF1 was associated with interferon production specifically, whilst HIF2 was associated with generic cytokine signalling as well as humoral and toll-like receptor immune responses. Neutrophil and myeloid cell signalling was enriched under hypoxia, alongside hallmark pathways associated with Tregs and macrophages. High-hypoxia MIBC tumours had increased expression of both suppressive and anti-tumour immune gene signatures and were associated with increased immune infiltrates. Overall, hypoxia is associated with increased inflammation for both suppressive and anti-tumour-related immune signalling and immune infiltrates, as seen in vitro and in situ using MIBC patient tumours.

Relapse patterns in early-PET negative, limited-stage Hodgkin lymphoma (HL) after ABVD with or without radiotherapy-a joint analysis of EORTC/LYSA/FIL H10 and NCRI RAPID trials

In the H10 and RAPID randomised trials, chemotherapy+radiotherapy (combined modalities treatment, CMT) was compared with chemotherapy (C) in limited-stage Hodgkin lymphoma (HL), with negative early positron emission tomography (ePETneg). We analysed patterns of relapses in the H10 trial, validated findings in the RAPID trial and performed a combined analysis stratified by trial. The impact of radiotherapy (RT) on risk of relapse was studied using adjusted Cox models, with time-varying effects. In H10, 1,059 ePETneg patients were included (465 European Organisation for Research and Treatment of Cancer (EORTC) favourable [F], 594 unfavourable [U]). Among the F patients, 2/227 (1%) relapsed after CMT, 30/238 (13%) after C: of these relapses, 21/30 (70%) occurred in less than 2 years and 25/30 (83%) affected originally involved areas. Among the U group, 16/292 (5%) relapsed after CMT: 8/16 (50%) in less than 2 years, 11/16 (69%) in originally involved areas. After C 30/302 (10%) relapsed: 27/30 (90%) in less than 2 years, and 26/30 (87%) in originally involved areas. Similar results were observed in 419 ePETneg RAPID patients (241 F, 128 U, 50 unclassified): among F patients, 6/118 (5%) relapsed after CMT; 13/123 (11%) after C: 11/13 (85%) in less than 2 years and 11/13 (85%) affecting originally involved areas. In U patients, 3/65 (5%) relapsed after CMT and 5/63 (8%) after C. In both trials, omitting RT in ePETneg HL resulted in more early relapses, mainly affecting originally involved areas. RT significantly reduced risk of early relapses in the combined stratified analysis.

Low CD8 T Cell Counts Predict Benefit from Hypoxia-Modifying Therapy in Muscle-Invasive Bladder Cancer

BACKGROUND

As hypoxia can drive an immunosuppressive tumour microenvironment and inhibit CD8+ T cells, we investigated if patients with low tumour CD8+ T cells benefitted from hypoxia-modifying therapy.

METHODS

BCON was a phase III trial that randomised patients with muscle-invasive bladder cancer (MIBC) to radiotherapy alone or with hypoxia-modifying carbogen plus nicotinamide (CON). Tissue microarrays of diagnostic biopsies from 116 BCON patients were stained using multiplex immunohistochemistry (IHC) with the markers CD8, CD4, FOXP3, CD68 and PD-L1, plus DAPI. Hypoxia was assessed using CA9 IHC (n = 111). Linked transcriptomic data (n = 80) identified molecular subtype. Relationships with overall survival (OS) were investigated using Cox proportional hazard models.

RESULTS

High (upper quartile) vs. low CD8 T cell counts associated with a better OS across the whole cohort at 16 years (n = 116; HR 0.47, 95% CI 0.28-0.78, p = 0.003) and also in the radiotherapy alone group (n = 61; HR 0.39, 95% CI 0.19-0.76, p = 0.005). Patients with low CD8+ T cells benefited from CON (n = 87; HR 0.63, 95% CI 0.4-1.0, p = 0.05), but those with high CD8 T cells did not (n = 27; p = 0.95). CA9 positive tumours had fewer CD8+ T cells (p = 0.03). Prognostic significance of low CD8+ T cells in the whole cohort remained after adjusting for clinicopathologic variables. Basal vs. luminal subtype had more CD8+ cells (p = 0.02) but was not prognostic (n = 80; p = 0.26). Exploratory analyses with other immune markers did not improve on findings obtained with CD8 counts.

CONCLUSIONS

MIBC with low CD8+ T cell counts may benefit from hypoxia-modifying treatment.

The ECHELON-2 Trial: 5-year results of a randomized, phase 3 study of brentuximab vedotin with chemotherapy for CD30-positive peripheral T-cell lymphoma

Background:

For patients with peripheral T-cell lymphoma (PTCL), outcomes using frontline treatment with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or CHOP-like therapy are typically poor. The ECHELON-2 study demonstrated that brentuximab vedotin plus cyclophosphamide, doxorubicin, and prednisone (A+CHP) exhibited statistically superior progression-free survival (PFS) per independent central review and improvements in overall survival versus CHOP for the frontline treatment of patients with systemic anaplastic large cell lymphoma or other CD30-positive PTCL.

Patients and methods:

ECHELON-2 is a double-blind, double-dummy, randomized, placebo-controlled, active-comparator phase III study. We present an exploratory update of the ECHELON-2 study, including an analysis of 5-year PFS per investigator in the intent-to-treat analysis group.

Results:

A total of 452 patients were randomized (1 : 1) to six or eight cycles of A+CHP (N = 226) or CHOP (N = 226). At median follow-up of 47.6 months, 5-year PFS rates were 51.4% [95% confidence interval (CI): 42.8% to 59.4%] with A+CHP versus 43.0% (95% CI: 35.8% to 50.0%) with CHOP (hazard ratio = 0.70; 95% CI: 0.53–0.91), and 5-year overall survival (OS) rates were 70.1% (95% CI: 63.3% to 75.9%) with A+CHP versus 61.0% (95% CI: 54.0% to 67.3%) with CHOP (hazard ratio = 0.72; 95% CI: 0.53–0.99). Both PFS and OS were generally consistent across key subgroups. Peripheral neuropathy was resolved or improved in 72% (84/117) of patients in the A+CHP arm and 78% (97/124) in the CHOP arm. Among patients who relapsed and subsequently received brentuximab vedotin, the objective response rate was 59% with brentuximab vedotin retreatment after A+CHP and 50% with subsequent brentuximab vedotin after CHOP.

Conclusions:

In this 5-year update of ECHELON-2, frontline treatment of patients with PTCL with A+CHP continues to provide clinically meaningful improvement in PFS and OS versus CHOP, with a manageable safety profile, including continued resolution or improvement of peripheral neuropathy.

Efficacy and Toxicity of Alternative Radiation Treatment Schemes for Patients With Hematologic Malignancies: A Collaborative ILROG COVID Era Report

Purpose/Objective(s)

The COVID19 pandemic required radiation oncologists (ROs) to consider shorter treatment courses to minimize patient and staff exposure and conserve healthcare resources. Hematologic ROs adopted hypofractionated radiation therapy (hRT) regimens according to guidelines published by the International Lymphoma Radiation Oncology Group (ILROG). We report for the first time the preliminary efficacy and toxicity of these novel hypofractionated regimens in the treatment of hematologic malignancies.

Materials/Methods

We conducted a multicenter, multinational retrospective study under the direction of the ILROG. All patients receiving hRT according to ILROG guidelines from 1/1/2020 to 8/31/2020 were included. Patient and treatment details were abstracted from separate institutional databases. Toxicity was graded using CTCAE v5.0.

Results

Ninety-three patients from 4 institutions treated with 114 RT courses were included. Patient and treatment details are displayed in Table 1. Median follow up for the cohort was 179 days, and 77 patients (82%) were alive at last follow up. Maximal toxicity experienced by patients included Grade 1 (n = 16), Grade 2 (n = 1) and Grade 3 (n = 1) toxicities. Of 80 sites with response assessment within the RT field, 69% of patients achieved a complete response (n = 55), 20% partial response (n = 16), 9% stable disease (n = 7), and 2% progressive disease (n = 2). No COVID19 infections during or after RT have been documented in this patient cohort.

Conclusion

HRT according to ILROG guidelines resulted in low rates of acute toxicity and reasonable short-term treatment efficacy. Longer follow up and comparison with control groups is needed to draw more definitive conclusions and will be presented at the Annual Meeting.

Systemic ALCL Treated in Routine Clinical Practice: Outcomes Following First-Line Chemotherapy from a Multicentre Cohort

INTRODUCTION

Brentuximab vedotin (BV)-CHP is the new standard regimen for first-line treatment of systemic anaplastic large cell lymphoma (sALCL). We undertook a retrospective analysis of consecutive patients diagnosed with sALCL, treated in routine practice, to serve as a benchmark analysis for comparison BV-CHP efficacy in routine practice.

METHODS

Patients aged 16 years or older with sALCL treated in seven UK and Australian centres and from 14 additional centres from the UK Haematological Malignancy Research Network database (n = 214). Treatment allocation was clinician choice and included best supportive care (BSC). Main outcomes were time to treatment failure (TTF) and overall survival (OS). Multivariable analysis for predictors of both TTF and OS was also undertaken.

RESULTS

The median age 52 years (range 16-93), 18% ECOG ≥ 3 and 40% of cases were ALK positive. CHOP (cyclophosphamide, adriamycin, vincristine, prednisolone) was employed in 152 (71%) of patients and CHOEP (CHOP + etoposide) in 4% of patients. For CHOP-treated patients overall response rate (ORR) was 65% and complete response (CR) 47%. Only 9% of patients underwent autologous stem cell transplant (ASCT). With 57 months median follow-up, 4-year TTF and OS were 41.2% (95% CI 33.1-49.1) and 58.9% (95% CI 50.3-66.5) respectively. Multivariable analysis showed ALK+ status was independently associated with superior TTF (HR 0.36, 95% CI 0.21-0.63) but not OS (0.44, 95% CI 0.18-1.07).

DISCUSSION

We present a retrospective analysis with mature follow-up of one of the largest multicentre populations of sALCL available, comparable to similar large retrospective studies. ALK status remains a strong predictor of outcomes.

CONCLUSION

These data serve as a robust benchmark for BV-CHP as the new standard of care for sALCL. Similar real-world evidence with BV-CHP will be desirable to confirm the findings of ECHELON-2.

Investigating Radiotherapy Response in a Novel Syngeneic Model of Prostate Cancer

The prostate cancer (PCa) field lacks clinically relevant, syngeneic mouse models which retain the tumour microenvironment observed in PCa patients. This study establishes a cell line from prostate tumour tissue derived from the Pten-/-/trp53-/- mouse, termed DVL3 which when subcutaneously implanted in immunocompetent C57BL/6 mice, forms tumours with distinct glandular morphology, strong cytokeratin 8 and androgen receptor expression, recapitulating high-risk localised human PCa. Compared to the commonly used TRAMP C1 model, generated with SV40 large T-antigen, DVL3 tumours are immunologically cold, with a lower proportion of CD8+ T-cells, and high proportion of immunosuppressive myeloid derived suppressor cells (MDSCs), thus resembling high-risk PCa. Furthermore, DVL3 tumours are responsive to fractionated RT, a standard treatment for localised and metastatic PCa, compared to the TRAMP C1 model. RNA-sequencing of irradiated DVL3 tumours identified upregulation of type-1 interferon and STING pathways, as well as transcripts associated with MDSCs. Upregulation of STING expression in tumour epithelium and the recruitment of MDSCs following irradiation was confirmed by immunohistochemistry. The DVL3 syngeneic model represents substantial progress in preclinical PCa modelling, displaying pathological, micro-environmental and treatment responses observed in molecular high-risk disease. Our study supports using this model for development and validation of treatments targeting PCa, especially novel immune therapeutic agents.

Role of Radiation Therapy in Patients With Relapsed/Refractory Diffuse Large B-Cell Lymphoma: Guidelines from the International Lymphoma Radiation Oncology Group

Approximately 30% to 40% of patients with diffuse large B-cell lymphoma (DLBCL) will have either primary refractory disease or relapse after chemotherapy. In transplant-eligible patients, those with disease sensitive to salvage chemotherapy will significantly benefit from high-dose therapy with autologous stem cell transplantation. The rationale for considering radiation therapy (RT) for selected patients with relapsed/refractory DLBCL as a part of the salvage program is based on data regarding the patterns of relapse and retrospective series showing improved local control and clinical outcomes for patients who received peritransplant RT. In transplant-ineligible patients, RT can provide effective palliation and, in selected cases, be administered with curative intent if the relapsed/refractory disease is localized. We have reviewed the indications for RT in the setting of relapsed/refractory DLBCL and provided recommendations regarding the optimal timing of RT, dose fractionation scheme, and treatment volume in the context of specific case scenarios.

Abstract B035: Radio-resistance of PTEN-deficient prostate tumors is enhanced by treatment-induced chemokine signaling and is associated with biochemical recurrence and development of metastasis

Copy number alterations of the tumor-suppressor gene PTEN occur frequently in primary prostate cancer and are prognostic for relapse post-radiotherapy (RT). Preclinical modelling supports elevated CXC-chemokine signaling as a critical mediator of PTEN-depleted disease progression, and therapeutic resistance. Our objective was to establish the correlation of PTEN-deficiency with CXC-chemokine signaling and its association with clinical outcome following RT. Techniques employed included gene cluster and survival analysis of prostate cancer datasets; in vitro biologic assays extending to RT-PCR, immunoblotting, clonogenic survival assays and flow cytometry; and the use of two in vivo PTEN-deficient xenograft models. Analysis of gene expression data from the MSKCC cohort characterized a PTENLOW/CXCR1HIGH/CXCR2HIGH cluster of tumors that associates with earlier time to biochemical recurrence (HR 5.87, p<0.001). Further analysis was conducted on a gene expression profile derived from the FASTMAN retrospective radiotherapy patient sample cohort (248 diagnostic biopsy samples with median follow-up data >90 months). Kaplan-Meier analysis confirmed that PTENLOW/CXCR1HIGH/CXCR2HIGH tumors were associated with a significantly reduced time to biochemical recurrence (HR 2.65, p<0.001) and the development of metastasis (HR: 3.51, p<0.001) following RT treatment. In vitro, CXCL-signaling was further amplified following exposure of PTEN-deficient CaP cell lines to ionizing radiation (IR; 2-3 Gy). Inhibition of CXCR1/2-signaling in all PTEN-depleted cell-based models increased IR sensitivity (dose enhancement range 1.13 to 1.39), mediated by apoptosis induction in DU145 cells (p53-mutant) or senescence in 22RV1 cells (p53-WT). Reconstitution of PTEN in PTEN-null PC3 cells abrogated the radiosensitivity afforded by a CXCR1/2-signaling blockade. In vivo, administration of a CXCR1/2-targeted pepducin (x1/2pal-i3) in combination with IR to PTEN-null PC3 and PTEN-depleted DU145 xenografts attenuated tumor growth and progression compared to control or radiation alone (p<0.001). Post-mortem analysis confirmed that x1/2pal-i3 administration attenuated IR-induced CXCL-signaling and antiapoptotic protein expression (Bcl-2, c-FLIP). Our data confirm the clinical association of PTEN-deficiency with elevated CXC-chemokine signaling in human prostate cancer, the association of this cluster with adverse clinical outcomes, and demonstrates that IR exposure selectively potentiates this signaling pathway in PTEN-deficient tumor cells. Interventions targeting CXC-chemokine signaling may provide an effective strategy to combine with radiotherapy, especially in locally advanced prostate cancers with known presence of PTEN-deficient foci.

Citation Format: Chris W.D. Armstrong, Jonathan A. Coulter, Chee Wee Ong, Pamela J. Maxwell, Karl T. Butterworth, Oksana Lyubomska, Melissa J. LaBonte, Silvia Berlingeri, Rebecca Gallagher, Steven M. Walker, Joe M. O’Sullivan, Suneil Jain, Ian G. Mills, Manuel Salto-Tellez, Timothy Illidge, Richard D. Kennedy, Kevin M. Prise, David J.J. Waugh. Radio-resistance of PTEN-deficient prostate tumors is enhanced by treatment-induced chemokine signaling and is associated with biochemical recurrence and development of metastasis [abstract]. In: Proceedings of the AACR Special Conference: Prostate Cancer: Advances in Basic, Translational, and Clinical Research; 2017 Dec 2-5; Orlando, Florida. Philadelphia (PA): AACR; Cancer Res 2018;78(16 Suppl):Abstract nr B035.

Radiotherapy and anti-PD-1/PD-L1 combinations in lung cancer: building better translational research platforms

Despite the unheralded success of immune checkpoint blockade in delivering durable responses for some patients with non-small-cell lung cancer (NSCLC), the majority of patients do not respond. PD-L1 tumour expression and pre-existing tumour T-cell infiltration have been correlated with improved clinical outcomes to anti-PD-1/anti-PD-L1. However, patients with tumours that are negative for PD-L1 expression can also respond to treatment. Strategies to combine other treatment modalities like radiotherapy (RT) with immune checkpoint inhibitors are being investigated as means of improving the response rates to PD-1/PD-L1 antibody blockade. RT induces immunogenic changes in cancer cells, can adaptively upregulate tumour cell PD-L1 expression and can improve the efficacy of anti-PD-1/anti-PD-L1 therapy. How we design future clinical trials in NSCLC also depends on practical considerations of delivering these treatment combinations, such as RT dose, fractionation and field volume, as well as scheduling with immune checkpoint blockade. Here, we review reasons for resistance to anti-PD-1/anti-PD-L1 and how RT may be utilised in combination with these drugs to enhance their effect by building better translational research platforms.

Immune Checkpoint Inhibitors in Lung Cancer - An Unheralded Opportunity?

Lung cancer remains the leading cause of cancer-related death worldwide, with non-small cell lung cancer accounting for 85% of the disease. Over 70% of patients present with locally advanced, non-resectable or metastatic disease and despite improvements in chemoradiotherapy regimens and the development of molecularly targeted agents, 5 year survival rates remain poor, with acquired resistance to novel targeted therapies becoming a growing concern. Currently there remains an unmet need in effectively treating and inducing durable responses in advanced disease. Targeting the immune system has, however, recently given hope of improving therapeutic outcomes for these patients. The notion that the immune system is capable of recognising and eliminating cancer cells is now a widely accepted phenomenon and growing evidence suggests lung cancer is an attractive target for such intervention. Recent success targeting the programmed death-1/programmed death-ligand 1 (PD-1/PD-L1) axis of immune checkpoint inhibition suggests a major immunotherapeutic advance in treating lung cancer and unheralded opportunity for such approaches to further improve outcome for patients. Currently there is considerable interest in combining anti-PD-1 or PD-L1 monoclonal antibodies with established standard of care therapies such as radiotherapy. Radiotherapy is known to be immunostimulatory and efforts are underway to combine and augment the efficacy of the immune checkpoint inhibitors further. This review outlines the interaction between lung cancer and the immune system, summarises current evidence supporting the use of monoclonal antibodies targeting the PD-1 axis in lung cancer and explores the potential of combining radiotherapy with immunotherapy to augment anti-tumour immune responses.

Radiotherapy and Immunotherapy Combinations in Non-small Cell Lung Cancer: A Promising Future?

The goal of re-programming the host immune system to target malignancy with durable anti-tumour clinical responses has been speculated for decades. In the last decade such speculation has been transformed into reality with unprecedented and durable responses to immune checkpoint inhibitors seen in solid tumours. This mini-review considers the mechanism of action of immune modulating agents and the potential for combination with radiotherapy in the treatment of non-small cell lung cancer.

Abstract 5034: The antitumor immune response generated by radiation therapy may be limited by tumor cell adaptive resistance and can be circumvented by PD-L1 blockade

Radiation therapy (RT) is administered to around 50% of all cancer patients making it one of the most important cancer treatments. In addition to the direct cytoreductive effect of RT there is increasing evidence that radiation-induces immunogenic tumor cell death. Despite the immunogenicity of RT-induced tumor cell death, RT delivered to tumours in the clinic rarely generates therapeutic systemic anti-cancer immune responses or ‘abscopal effects’.

Here we show that tumor infiltrating CD8+ cytotoxic T lymphocytes (CTL) have increased expression of PD-1 following RT in vivo. Moreover, our data demonstrate that treatment of established syngeneic tumors with RT leads to upregulation of tumor cell expression of PD-L1 in vivo but not when cells are irradiated in vitro. Using depleting antibodies we determined that the depletion of CD8+ T cells but not CD4+ T cells or NK cells could abrogate this RT-induced increase in tumor cell expression of PD-L1 in vivo. Furthermore, silencing of IFNγR1 using ShRNA confirmed that this process was dependent on CD8+ T cell production of IFNγ suggesting an adaptive upregulation of PD-L1 following RT occurs in response to CTL activation. This novel finding suggests that the immunogenicity of RT may be limited via the PD-L1/PD-1 signalling axis and may contribute to treatment failure.

We next sought to determine whether blockade of the PD-1/PD-L1 signalling axis could enhance the therapeutic response to RT. Our study demonstrates that administration of either an anti-PD-1 or anti-PD-L1 mAb in combination with RT leads to substantially improved survival when compared to either monotherapy alone with approximately 60% of treated mice undergoing a complete response. In addition, our data reveal that combination therapy generates long-term immunological memory in mice that have undergone complete response protecting against tumor rechallenge.

This is the first report to our knowledge that demonstrates adaptive resistance through the upregulation of tumour cell PD-L1 expression in response to an RT-induced CTL response. This study demonstrates the potential for enhancing the efficacy of conventional RT through blockade of the PD-1/PD-L1 axis and warrants clinical evaluation.

Citation Format: Simon J. Dovedi, Graznya Lipowska-Bhalla, Eleanor Cheadle, Edmund Poon, Michelle Morrow, Ross Stewart, Robert Wilkinson, Jamie Honeychurch, Timothy Illidge. The antitumor immune response generated by radiation therapy may be limited by tumor cell adaptive resistance and can be circumvented by PD-L1 blockade. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5034. doi:10.1158/1538-7445.AM2014-5034

4 Gy versus 24 Gy radiotherapy for patients with indolent lymphoma (FORT): a randomised phase 3 non-inferiority trial

BACKGROUND

Follicular lymphoma has been shown to be highly radiosensitive with responses to doses as low as 4 Gy in two fractions. This trial was designed to explore the dose response for follicular lymphoma comparing 4 Gy in two fractions with 24 Gy in 12 fractions

METHODS

FORT is a prospective randomised, unblinded, phase 3 non-inferiority study comparing radiotherapy given as 4 Gy in two fractions with a standard dose of 24 Gy in 12 fractions. Entry criteria included all patients aged over 18 years, having local radiotherapy for radical or palliative local control, with follicular lymphoma or marginal zone lymphoma, who had received no previous treatment for at least 1 month before. The primary outcome was time to local progression analysed on an intention-to-treat basis. Randomisation was centralised through the Cancer Research UK and University College London Cancer Trials Centre. Radiotherapy target sites were randomised (1:1) with minimisation stratified by histology (follicular lymphoma vs marginal zone lymphoma), treatment intent (palliative or curative) and centre. This trial is registered with ClinicalTrials.gov number, NCT00310167.

FINDINGS

299 sites were randomly assigned to 24 Gy and 315 sites to 4 Gy between April 7, 2006, and June 8, 2011, at 43 centres in the UK. After a median follow-up of 26 months (range 0·39-75·4), 91 local progressions had been recorded (21 in the 24 Gy group and 70 in the 4 Gy group). Time to local progression with 4 Gy was not non-inferior to 24 Gy (hazard ratio 3·42, 95% CI 2·09-5·55, p<0·0001). Eight (3%) of 282 patients in the 24 Gy group and four (1%) of 300 in the 4 Gy group had acute grade 3-4 toxic effects. Four (1%) patients in the 24 Gy group and four (1%) patients in the 4 Gy group had late toxic effects. Mucositis was the most common event in the 24 Gy group (two patients with acute mucositis and two with late mucositis; all grade 3) and was not reported in the 4 Gy group. The most common acute effect was pain at the site of irradiation (two patients in the 4 Gy group, one patient in the 24 Gy group; all grade 3), and the most common late effect was fatigue (two patients in the 4 Gy group, one patient in the 24 Gy group; all grade 3).

INTERPRETATION

24 Gy in 12 fractions is the more effective radiation schedule for indolent lymphoma and should be regarded as the standard of care. However, 4 Gy remains a useful alternative for palliative treatment.

FUNDING

Cancer Research UK.

Phase II study of gemcitabine and bexarotene (GEMBEX) in the treatment of cutaneous T-cell lymphoma

BACKGROUND

Both gemcitabine and bexarotene are established single agents for the treatment of cutaneous T-cell lymphoma (CTCL). We investigated the feasibility and efficacy of combining these drugs in a single-arm phase II study.

METHODS

Cutaneous T-cell lymphoma patients who had failed standard skin-directed therapy and at least one prior systemic therapy were given four cycles of gemcitabine and concurrent bexarotene for 12 weeks. Responders were continued on bexarotene maintenance until disease progression or unacceptable toxicity.

RESULTS

The median age was 65 years, stage IB (n=5), stage IIA (n=2), stage IIB (n=8), stage III (n=8) and stage IVA (n=12), 17 patients were erythrodermic, 17 patients were B1, and 10 patients were both erythrodermic and B1. Thirty (86%) patients completed four cycles of gemcitabine. In all, 80.0% of patients demonstrated a reduction in modified Severity-Weighted Assessment Tool (mSWAT) score although the objective disease response rate at 12 weeks was 31% (partial response (PR) 31%) and at 24 weeks 14% (PR 14%, stable disease (SD) 23%, progressive disease (PD) 54%, not evaluable 9%). Median progression-free survival was 5.3 months and median overall survival was 21.2 months.

CONCLUSION

The overall response rate of the combination did not reach the specified target to proceed further and is lower than that previously reported for gemcitabine as a single agent.

Breast cancer risk following Hodgkin lymphoma radiotherapy in relation to menstrual and reproductive factors

BACKGROUND

Women treated with supradiaphragmatic radiotherapy (sRT) for Hodgkin lymphoma (HL) at young ages have a substantially increased breast cancer risk. Little is known about how menarcheal and reproductive factors modify this risk.

METHODS

We examined the effects of menarcheal age, pregnancy, and menopausal age on breast cancer risk following sRT in case-control data from questionnaires completed by 2497 women from a cohort of 5002 treated with sRT for HL at ages <36 during 1956-2003.

RESULTS

Two-hundred and sixty women had been diagnosed with breast cancer. Breast cancer risk was significantly increased in patients treated within 6 months of menarche (odds ratio (OR) 5.52, 95% confidence interval (CI) (1.97-15.46)), and increased significantly with proximity of sRT to menarche (Ptrend<0.001). It was greatest when sRT was close to a late menarche, but based on small numbers and needing reexamination elsewhere. Risk was not significantly affected by full-term pregnancies before or after treatment. Risk was significantly reduced by early menopause (OR 0.55, 95% CI (0.35-0.85)), and increased with number of premenopausal years after treatment (Ptrend=0.003).

CONCLUSION

In summary, this paper shows for the first time that sRT close to menarche substantially increases breast cancer risk. Careful consideration should be given to follow-up of these women, and to measures that might reduce their future breast cancer risk.

U.K. consensus statement on safe clinical prescribing of bexarotene for patients with cutaneous T-cell lymphoma

BACKGROUND

Bexarotene is a synthetic retinoid from the subclass of retinoids called rexinoids which selectively activate retinoid X receptors. It has activity in cutaneous T-cell lymphoma (CTCL) and has been approved by the European Medicines Agency since 1999 for treatment of the skin manifestations of advanced-stage (IIB-IVB) CTCL in adult patients refractory to at least one systemic treatment. In vivo bexarotene produces primary hypothyroidism which may be managed with thyroxine replacement. It also affects lipid metabolism, typically resulting in raised triglycerides, which requires prophylactic lipid-modification therapy. Effects on neutrophils, glucose and liver function may also occur. These side-effects are dose dependent and may be controlled with corrective therapy or dose adjustments.

OBJECTIVES

  To produce a U.K. statement outlining a bexarotene dosing schedule and monitoring protocol to enable bexarotene prescribers to deliver bexarotene safely for optimal effect.

METHODS

 Leaders from U.K. supraregional centres produced this consensus statement after a series of meetings and a review of the literature.

RESULTS

 The statement outlines a bexarotene dosing schedule and monitoring protocol. This gives instructions on monitoring and treating thyroid, lipid, liver, blood count, creatine kinase, glucose and amylase abnormalities. The statement also includes algorithms for a bexarotene protocol and lipid management, which may be used in the clinical setting.

CONCLUSION

 Clinical prescribing of bexarotene for patients with CTCL requires careful monitoring to allow safe administration of bexarotene at the optimal dose.

Comparisons of dosimetric approaches for fractionated radioimmunotherapy of non-Hodgkin lymphoma

AIM

The aim of this study was to compare different dosimetric approaches on therapy naïve patients enrolled in a multicentre fractionated radioimmunotherapy trial, to determine which methodological approach correlates with bone marrow toxicity.

METHODS

Twenty-height non-Hodgkin lymphoma patients were treated with one or two fractions of 90Y-Ibritumomab-Tiuxetan (11.1 MBq/kg) 8 to 12 weeks apart in four different institutions. Quantitative imaging with 111In-Ibritumomab-Tiuxetan (185 MBq) was performed at 0, 1, 4 and 7 days after infusion, starting two weeks before the therapeutic administration. A whole-body (WB) CT scan was also acquired prior to the 111In-Ibritumomab injection, for attenuation correction purposes and was segmented to derive patient-specific organ masses. All dosimetry processing was centralized in a single institution. The first method (M_2D) was based on geometric mean WB scans, corrected for attenuation, scatter and organs superposition. The second method (M_2.5D) was based on the computed assisted matrix inversion approach and used segmented CT scans. The third method (M_3D) used iterative reconstruction of tomographic scans, corrected for attenuation, scatter and collimator response. Absorbed doses were estimated for lungs, liver, kidneys and spleen using MIRD S values adjusted for organ masses. Bone marrow (BM) absorbed doses were evaluated according to imaging methods (3) and compared to blood-based approaches.

RESULTS

For some patients, organ masses such as liver or spleen significantly differed from male/female reference masses, whereas lungs and kidneys masses were relatively constant. Except for lungs, absorbed doses estimated by M_2D were higher than those from M_2.5D and these, in turn, were higher that those calculated from M_3D (Wilcoxon P<8.6e-4). Median organ absorbed dose estimates were equivalent for both fractions except for the spleen. In fact, spleen absorbed doses for the second fraction were lower than those for the first fraction, regardless of the approach. Possible explanations are that patient spleen masses were kept constant for analysis of both fractions and/or that spleen uptake was lowered after the first fraction. Estimation of BM absorbed doses from blood sampling was unable to predict platelet toxicity, but image-based methods performed better. Additionally, for most organs, the absorbed dose delivered by the first fraction could predict that delivered by the second fraction.

CONCLUSION

These results confirm that different acquisition/processing protocols will lead to statistically different absorbed doses. Additionally, image-based dosimetric approaches are needed in order to correlate absorbed dose to bone marrow toxicity.