Abscopal Regressions of Lymphoma After Involved-Site Radiation Therapy Confirmed by Positron Emission Tomography

Neoadjuvant lutetium PSMA, the TIME and immune response in high-risk localized prostate cancer

High-risk localized prostate cancer remains a lethal disease with high rates of recurrence, metastases and death, despite attempts at curative local treatment including surgery. Disease recurrence is thought to be a result of failure of local control and occult micrometastases. Neoadjuvant strategies before surgery have been effective in many cancers, but, to date, none has worked in this setting for prostate cancer. Prostate-specific membrane antigen (PSMA)-based theranostics is an exciting and rapidly evolving field in prostate cancer. The novel intravenous radionuclide therapy, [177Lu]Lu-PSMA-617 (lutetium PSMA) has been shown to be effective in treating men with metastatic castration-resistant prostate cancer, targeting cells expressing PSMA throughout the body. When given in a neoadjuvant setting, lutetium PSMA might also improve long-term oncological outcomes in men with high-risk localized disease. A component of radiotherapy is potentially an immunogenic form of cancer cell death. Lutetium PSMA could cause cancer cell death, resulting in release of tumour antigens and induction of a tumour-specific systemic immune response. This targeted radioligand treatment has the potential to treat local and systemic tumour sites by directly targeting cells that express PSMA, but might also act indirectly via this systemic immune response. In selected patients, lutetium PSMA could potentially be combined with systemic immunotherapies to augment the antitumour T cell response, and this might produce long-lasting immunity in prostate cancer.

Contemporary radiation therapy use in Hodgkin lymphoma

Radiation therapy assumes a pivotal role in Hodgkin lymphoma management, especially within combined modality therapy. It serves as a cornerstone in early-stage disease and in mitigating high-risk instances of local relapse in advanced stages. Over recent decades, radiation therapy has undergone significant advancements, notably alongside diagnostic imaging improvements, facilitating the reduction of radiation field size and dosage. This progress has notably led to minimized toxicity while upholding treatment efficacy. This comprehensive review extensively evaluates the indications and advancements in radiation therapy for Hodgkin lymphoma, with a primary focus on enhancing treatment efficacy while minimizing radiation-related toxicities. The exploration encompasses a detailed examination of various radiation fields, techniques and delivery modalities employed in Hodgkin lymphoma treatment, including intensity-modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT), and proton therapy. It delves into the intricacies of optimal dose selection and treatment planning strategies aimed at achieving maximal disease control while concurrently minimizing the risk of long-term side effects.

Incorporating Immunotherapy with Radiotherapy for Lymphomas

Radiotherapy and/or chemotherapy have been used for nearly 100 years to treat lymphoma. Recently, immunotherapy has been incorporated into the treatment of lymphomas. Here, we will review both the role of immunotherapy in lymphoma as well as the feasibility of incorporating immunotherapies with conventional lymphoma treatments, especially radiotherapy. Immunotherapy agents include checkpoint inhibitors that target the PD-1/PD-L1 axis, CTLA-4, or CD47. In addition, other immunotherapy agents such as bi-specific antibodies and CD19 CAR-T cell therapy are being implemented in various non-Hodgkin's lymphomas. Extrapolating from observations in other disease sites and incorporating immunotherapy with conventional treatments of lymphoma, including radiotherapy, may have opposing effects. Radiotherapy may stimulate anti-tumor immune responses that synergize with immunotherapies. In contrast, radiotherapy, as well as chemotherapy, may also induce local and systemic immune dysfunction which reduces the efficacy of immunotherapies. With newer radiation treatment techniques and limited radiation fields, it is likely that the efficacy of immunotherapy can be maintained when included with conventional treatments. Therefore, there remains an unmet need to better understand the role of immunotherapy alone and in combination with current treatments in lymphoma patients.

Reappraisal of the role of radiation therapy in lymphoma treatment

Radiation therapy (RT) for lymphomas has improved dramatically with modern imaging and treatment techniques, encompassing only the necessary volume with minimal doses to normal structures. Prescribed radiation doses are reduced, and fractionation schedules are under revision. With effective systemic treatment only initial macroscopic disease is irradiated. With no or less effective systemic treatment, possible microscopic disease is also included. Risks of long-term side effects of RT have diminished dramatically and should be weighed against risks from more systemic treatment or increased risk of relapse. Lymphoma patients are often elderly, they tolerate modern limited RT very well. Lymphomas refractory to systemic treatments often remain radioresponsive, and brief, mild RT may offer effective palliation. New roles for RT are emerging with immune therapies. RT for "bridging," keeping the lymphoma under control while waiting for immune therapy, is well established. Enhancement of the immune response to lymphomas, so-called "priming," is being intensively researched.

Systemic Abscopal Effect of Low-dose Radiotherapy (2 Gy ×2) against Palatine Tonsil Follicular Lymphoma

A 52-year-old man presented with palatine tonsillar swelling caused by follicular lymphoma. His tumor burden was low, but exacerbation of snoring and dysphagia was observed. Considering the first wave of coronavirus disease 2019 (COVID-19) pandemic, he received palliative 4-Gy irradiation to the tonsils in 2 fractions, which induced partial regression of tonsillar swellings and eradication of the circulating lymphoma cells. We suggest that low-dose radiotherapy triggered an abscopal effect of lymphoma, which allowed the patient time to receive COVID-19 vaccination before starting immunosuppressive chemo-immunotherapy.

Enhanced systemic antilymphoma immune response by photothermal therapy with CpG deoxynucleotide coated nanoparticles

We investigated a novel mechanism of in situ vaccination in a lymphoma model. Radiation (RT) can induce abscopal responses in pre-clinical lymphoma models but has not translated to clinical efficacy. We hypothesized that immune stimulation with CpG deoxynucleotides could enhance abscopal effects induced by radiation or by photothermal therapy (PTT), which has been shown to have an immune stimulatory effect in solid tumors but has not been studied in lymphoma. Here, we designed a branched gold nanoparticle (BNP) platform to carry CpGs while maintaining PTT function and compared the immunologic profile of the tumor microenvironment after PTT or RT in a dual flank lymphoma model. One flank was treated with CpG with RT or CpG with PTT and the other tumor was left untreated. We found that the CpG/PTT groups had significant reduction in growth in both treated (primary) and untreated (secondary) tumors suggesting an improved abscopal response, with a concomitant increase in CD8/CD4 ratio and cytotoxic T cell/regulatory T cell ratio in both the primary and secondary tumor compared with CpG/RT. Dendritic cells in the primary and secondary draining lymph nodes had increased maturation markers in the CpG/PTT group, and the effector memory T cells (both CD4 and CD8) in the secondary tumor and the spleen were increased, suggesting a systemic vaccination effect. These data suggest that in a lymphoma model, PTT using a CpG nanoparticle platform resulted in enhanced in situ vaccination and abscopal response compared with RT.

A Patient-Level Data Meta-analysis of the Abscopal Effect

Purpose

The abscopal effect is defined when a form of local therapy causes tumor regression of both the target lesion and any untreated tumors. Herein cases of the abscopal effect were systematically reviewed and a patient-level data analysis was performed for clinical predictors of both duration of response and survival.

Methods and Materials

The Population, Intervention, Control, Outcome, Study (PICOS) design approach, Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) literature selection process, and Meta-analysis of Observational Studies in Epidemiology (MOOSE) were used to find articles published before September 2019 in MEDLINE/PubMed and Google Scholar. Inclusion criteria were (1) population: patients with reported abscopal response; (2) intervention: documented treatment(s); (3) control: none; (4) outcomes: overall and progression-free survival; and (5) setting: retrospective case reports. Time from treatment until abscopal response and time from abscopal response until progression/death were calculated. Univariate and multivariate analyses were conducted for survival outcomes.

Results

Fifty studies (n = 55 patients) were included. Median age was 65 years (interquartile range [IQR], 58-70) and 62% were male. Fifty-four (98%) patients received radiation therapy, 34 (62%) received radiation therapy alone, 5 (9.1%) underwent surgery, 4 (7.3%) received chemotherapy, and 11 (20%) received immunotherapy. Median total dose was 32 Gy (IQR, 25.5-48 Gy) and median dose per fraction was 3 Gy (IQR, 2-7.2). Median time until abscopal response was 4 months (IQR, 1-5; min 0.5, max 24). At 5 years, overall survival was 63% and distant progression-free survival was 45%. No variables had statistical significance in predicting duration of response or survival.

Conclusions

Almost all reported cases of the abscopal response are after radiation therapy; however, there are no known predictors of duration of response or survival in this population.

'Le Roi est mort, vive le Roi': New Roles of Radiotherapy in the Treatment of Lymphomas in Combination With Immunotherapy

BACKGROUND

immunotherapy (IT), including checkpoint inhibitors (CIs) and Chimeric Antigen Receptor T cell therapy (CAR-T) revolutionized the treatment of relapsing or refractory (r/r) lymphoma. Several preliminary experiences evaluated concomitant administration of radiotherapy and IT.

METHODS

we performed a systematic review of current literature as of March 30, 2020. A total of 1090 records was retrieved, 42 articles were selected on the basis of title and abstract and, after the removal of analyses with no original data or insufficient clinical information, 28 papers were included in the review.

RESULTS

previous studies were mostly represented by case reports/series or small cohorts. Nonetheless, combination of radiotherapy and CIs or CAR-T led to promising outcomes, resulting in extremely high rates of complete response and improving progression free and overall survival compared with data from recent clinical trials. Combination of RT and CIs had a fair toxicity profile with no reports of severe side effects. Within the limits of the small cohorts retrieved, RT seems a superior option compared with systemic treatment as a 'bridge' to CAR-T and could as well reduce severe complications rates. Radiotherapy could elicit immune response against lymphoma, as demonstrated by multiple cases of abscopal effect and its inclusion in anti-neoplastic vaccines protocols.

CONCLUSION

The results of this review warrant the evaluation of combination of RT and immunotherapy in larger and preferably prospective and randomized cohorts to confirm these preliminary impressive outcomes. The optimal dose, fractionation and timing of RT still have to be clarified.

How to manage early-stage follicular lymphoma

INTRODUCTION

Early-stage follicular lymphoma (FL) is characterized by good prognosis and can be cured with involved-field radiotherapy (IF-RT) in most cases. PET scan is a milestone of diagnostic work-up, with the aim of identifying a truly localized disease; however, staging in most of the studies was without PET.

AREAS COVERED

We have searched in MEDLINE (inclusive dates 1994-2020) data about localized FL management. While high-quality evidence is lacking, current guidelines recommend IFRT or involved-site RT as first-line treatment in limited stages FL. Since a significant proportion of disease relapse occurred in non-irradiated areas, it has been hypothesized that occult disease could be present at diagnosis and could persist after RT, contributing to relapse. Available treatment options include watch-and-wait, chemotherapy, RT plus chemo- or chemo-immunotherapy, and RT combined with rituximab (R).

EXPERT OPINION

RT combined with chemotherapy could increase PFS, but a clear OS benefit is lacking and toxic effects could be unacceptable. A promising strategy is represented by R combined with IF-RT, with low relapse rate outside the radiation fields and without the toxicity reported with chemotherapy. The study of prognostic factors in PET-staged patients, the reduction of RT fields and doses, and a response-adapted strategy represent new perspectives to investigate.