FDG-PET response and outcome from anti-PD-1 therapy in metastatic melanoma

Curing Stage IV Melanoma: Where Have We Been and Where Are We?

Little more than 10 years ago, metastatic melanoma was considered to have one of the poorest cancer outcomes, associated with a median overall survival of 6-8 months. Cytotoxic chemotherapy offered modest response rates of 20%-30%, but no clear survival benefit. Patients were routinely enrolled in clinical trials as their first-line therapy in the search for effective novel therapeutics. Remarkable developments in molecular biology, cancer genomics, immunology, and drug discovery have dominated the early part of the 21st century, and nowhere have the benefits been better realized than in the transformation of outcomes for patients with metastatic melanoma: since 2011, 14 new agents have been approved that significantly increase survival, with long-term remissions and, possibly now, potential for cure. Even so, there is still much work to be done, given that most treated patients still die of their disease. Although most survival gains have so far been realized for cutaneous melanoma, improving treatment options for those 10% of patients with rarer, noncutaneous melanomas is a high priority. Key novel therapeutic approaches aimed at improving outcomes with potential for curing patients with melanoma are considered.

Positron Emission Tomography/Computed Tomography Transformation of Oncology: Melanoma and Skin Malignancies

Skin cancers are the most common cancers, with melanoma resulting in the highest cause of death in this category. Accurate clinical, histologic, and imaging staging with fludeoxyglucose positron emission tomography (FDG PET) is most important to guide patient management. Whilst surgical excision with clear margins is the gold-standard treatment for primary cutaneous melanoma, targeted therapies have generated remarkable and rapid clinical responses in melanoma, for which FDG PET also plays an important role in assessment of treatment response and post-therapy surveillance. Non-FDG PET tracers, advanced PET technology, and PET radiomics may potentially change the landscape of the utilization of PET in the imaging of patients with cutaneous malignancies.

PET/Computed Tomography Transformation of Oncology: Immunotherapy Assessment

Immunotherapy approaches have changed the treatment landscape in a variety of malignancies with a high anti-tumor response. Immunotherapy may be associated with novel response and progression patterns that pose a substantial challenge to the conventional criteria for assessing treatment response, including response evaluation criteria in solid tumors (RECIST) 1.1. In addition to the morphologic details provided by computed tomography (CT) and MRI, hybrid molecular imaging emerges as a comprehensive imaging modality with the capacity to interrogate pathophysiological mechanisms like glucose metabolism. This review highlights the current status of 2-deoxy-2-[18F]fluoro-D-glucose positron emission tomography/computed tomography (18F-FDG PET/CT) in prognostication, response monitoring, and identifying immune-related adverse events. Furthermore, it investigates the potential role of novel immuno-PET tracers that could complement the utilization of 18F-FDG PET/CT by imaging the specific pathways involved in immunotherapeutic strategies.

Melanoma-Modern Treatment for Metastatic Melanoma

ABSTRACT

Traditional chemotherapy has been ineffective in the treatment of metastatic melanoma. Until the use of checkpoint inhibitors, patients had very limited survival. Since the original US Food and Drug Administration approval of ipilimumab over a decade ago, the armamentarium of immunotherapeutic agents has expanded to include programmed cell death protein 1 and lymphocyte activation gene 3 antibodies, requiring a nuanced approach to the selection of frontline treatments, managing patients through recurrence and progression, and determining length of therapy. Herein, we review the existing evidence supporting current standard immunotherapy regimens and discuss the clinical decision-making involved in treating patients with metastatic melanoma with checkpoint inhibitors.

CXCL13 Positive Cells Localization Predict Response to Anti-PD-1/PD-L1 in Pulmonary Non-Small Cell Carcinoma

Background: Immune checkpoint inhibitors (ICIs) have revolutionized non-small cell lung cancers (NSCLCs) treatment, but only 20-30% of patients benefit from these treatments. Currently, PD-L1 expression in tumor cells is the only clinically approved predictor of ICI response in lung cancer, but concerns arise due to its low negative and positive predictive value. Recent studies suggest that CXCL13+ T cells in the tumor microenvironment (TME) may be a good predictor of response. We aimed to assess if CXCL13+ cell localization within the TME can predict ICI response in advanced NSCLC patients. Methods: This retrospective study included 65 advanced NSCLC patients treated with Nivolumab/Pembrolizumab at IUCPQ or CHUM and for whom a pretreatment surgical specimen was available. Good responders were defined as having a complete radiologic response at 1 year, and bad responders were defined as showing cancer progression at 1 year. IHC staining for CXCL13 was carried out on a representative slide from a resection specimen, and CXCL13+ cell density was evaluated in tumor (T), invasive margin (IM), non-tumor (NT), and tertiary lymphoid structure (TLS) compartments. Cox models were used to analyze progression-free survival (PFS) and overall survival (OS) probability, while the Mann-Whitney test was used to compare CXCL13+ cell density between responders and non-responders. Results: We showed that CXCL13+ cell density localization within the TME is associated with ICI efficacy. An increased density of CXCL13+ cells across all compartments was associated with a poorer prognostic (OS; HR = 1.22; 95%CI = 1.04-1.42; p = 0.01, PFS; HR = 1.16; p = 0.02), or a better prognostic when colocalized within TLSs (PFS; HR = 0.84, p = 0.03). Conclusion: Our results support the role of CXCL13+ cells in advanced NSCLC patients, with favorable prognosis when localized within TLSs and unfavorable prognosis when present elsewhere. The concomitant proximity of CXCL13+ and CD20+ cells within TLSs may favor antigen presentation to T cells, thus enhancing the effect of PD-1/PD-L1 axis inhibition. Further validation is warranted to confirm the potential relevance of this biomarker in a clinical setting.

The features and management of acquired resistance to PD1-based therapy in metastatic melanoma

BACKGROUND

Anti-PD-1 therapy (PD1) either alone or with anti-CTLA-4 (CTLA4), has high initial response rates, however 20% of patients (pts) with complete response (CR) and 30% with partial response (PR) within 12 months of treatment experience subsequent disease progression by 6 years. The nature and optimal management of this acquired resistance (AR) remains unknown.

METHODS

Pts from 16 centres who responded to PD1-based therapy and who later progressed were examined. Demographics, disease characteristics and subsequent treatments were evaluated.

RESULTS

299 melanoma pts were identified, median age 64y, 44% BRAFV600m. 172 (58%) received PD1 alone, 114 (38%) PD1/CTLA4 and 13 (4%) PD1 and an investigational drug. 90 (30%) pts had CR, 209 (70%) PR. Median time to AR was 12.6 mo (95% CI, 11.3, 14.2). Most (N = 193, 65%) progressed in a single organ site, and in a solitary lesion (N = 151, 51%). The most frequent sites were lymph nodes (38%) and brain (25%). Management at AR included systemic therapy (ST, 45%), local therapy (LT) +ST (31%), LT alone (21%), or observation (3%). There was no statistical difference in PFS2 or OS based on management, however, PFS2 was numerically superior for pts treated with ST alone who progressed off PD1 therapy than those who progressed on PD1 (2-year PFS2 42% versus 25%, p = 0.249). mOS from AR was 38.0 months (95% CI, 29.5-NR); longer in single-site versus multi-site progression (2-year OS 70% vs 54%, p < 0·001).

CONCLUSIONS

Acquired resistance to PD1 therapy in melanoma is largely oligometastatic, and pts may have a favorable survival outcome following salvage treatment.

Predictive Factors in Metastatic Melanoma Treated with Immune Checkpoint Inhibitors: From Clinical Practice to Future Perspective

The introduction of immunotherapy revolutionized the treatment landscape in metastatic melanoma. Despite the impressive results associated with immune checkpoint inhibitors (ICIs), only a portion of patients obtain a response to this treatment. In this scenario, the research of predictive factors is fundamental to identify patients who may have a response and to exclude patients with a low possibility to respond. These factors can be host-associated, immune system activation-related, and tumor-related. Patient-related factors can vary from data obtained by medical history (performance status, age, sex, body mass index, concomitant medications, and comorbidities) to analysis of the gut microbiome from fecal samples. Tumor-related factors can reflect tumor burden (metastatic sites, lactate dehydrogenase, C-reactive protein, and circulating tumor DNA) or can derive from the analysis of tumor samples (driver mutations, tumor-infiltrating lymphocytes, and myeloid cells). Biomarkers evaluating the immune system activation, such as IFN-gamma gene expression profile and analysis of circulating immune cell subsets, have emerged in recent years as significantly correlated with response to ICIs. In this manuscript, we critically reviewed the most updated literature data on the landscape of predictive factors in metastatic melanoma treated with ICIs. We focus on the principal limits and potentiality of different methods, shedding light on the more promising biomarkers.

Discontinuation of anti‑programmed cell death protein 1 immune checkpoint inhibition after complete remission in head and neck squamous cell carcinoma: A case report and literature review

Programmed cell death protein 1 (PD-1) inhibition plays a central role in the current treatment of recurrent or metastatic head and neck squamous cell carcinoma (R/M-HNSCC). Some patients achieve a durable response, and even complete remission (CR) is possible, though it occurs rarely. In cases of durable CR, there are no guidelines regarding a possible discontinuation of immunotherapy. Since clinical experience on this issue is limited, the present study reported on a case of a durable CR following discontinuation of PD-1 inhibition in R/M-HNSCC and additionally presented an overview on the current literature. The present study reported on a case of CR of recurrent oropharyngeal cancer after four cycles of PD-1 monotherapy with Nivolumab. The therapy was discontinued after overall 46 cycles. Even after 3 more years of follow-up, there was no sign of tumor recurrence. Overall, according to reports from the literature, CR seems to be an indicator for durable disease control after therapy discontinuation. Since data on therapy termination is rare, decisions about when to stop successful immunotherapy in R/M-HNSCC have to be made individually for each patient.

Neoadjuvant Immunotherapy for Non-Small Cell Lung Cancer

Immune checkpoint blockade (ICB) has improved outcomes for patients with advanced non-small cell lung carcinoma (NSCLC). Building off of this, it has been hypothesized that the utilization of ICB early during the disease course may be advantageous, particularly in the neoadjuvant setting prior to definitive surgical resection. Preclinical studies have suggested that a more potent immune response may be induced by neoadjuvant ICB in the presence of a higher antigen burden and intact tumor draining lymph nodes. Recent clinical trials evaluating neoadjuvant ICB with or without chemotherapy combinations in patients with resectable NSCLC led to improved pathological responses and longer event-free survival when neoadjuvant ICB was added to chemotherapy. Surgical outcomes were also supportive of this approach, with encouraging rates of pathological downstaging. Additionally, the availability of pre-treatment biopsy samples and post-treatment surgical resection tissues facilitates the conducting of correlative studies that continue to improve our understanding of the mechanisms of response and resistance to ICB. As long-term survival outcomes from ongoing clinical trials are awaited, several important questions require further investigation, including the optimal duration of neoadjuvant therapy, the clinical endpoints most predictive of long-term outcomes, and translational studies that should be investigated in future trial designs. Additionally, the optimal clinical management of patients with residual disease at the time of surgical resection and those who experience recurrence remains to be determined. In this review, we will (1) discuss the rationale behind neoadjuvant ICB-based therapy in NSCLC, (2) summarize the clinical data available thus far, and (3) highlight unanswered questions that need to be addressed in future studies to maximize the clinical benefits of this approach.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of melanoma, version 3.0

Since the first approval for immune checkpoint inhibitors (ICIs) for the treatment of cutaneous melanoma more than a decade ago, immunotherapy has completely transformed the treatment landscape of this chemotherapy-resistant disease. Combination regimens including ICIs directed against programmed cell death protein 1 (PD-1) with anti-cytotoxic T lymphocyte antigen-4 (CTLA-4) agents or, more recently, anti-lymphocyte-activation gene 3 (LAG-3) agents, have gained regulatory approvals for the treatment of metastatic cutaneous melanoma, with long-term follow-up data suggesting the possibility of cure for some patients with advanced disease. In the resectable setting, adjuvant ICIs prolong recurrence-free survival, and neoadjuvant strategies are an active area of investigation. Other immunotherapy strategies, such as oncolytic virotherapy for injectable cutaneous melanoma and bispecific T-cell engager therapy for HLA-A*02:01 genotype-positive uveal melanoma, are also available to patients. Despite the remarkable efficacy of these regimens for many patients with cutaneous melanoma, traditional immunotherapy biomarkers (ie, programmed death-ligand 1 expression, tumor mutational burden, T-cell infiltrate and/or microsatellite stability) have failed to reliably predict response. Furthermore, ICIs are associated with unique toxicity profiles, particularly for the highly active combination of anti-PD-1 plus anti-CTLA-4 agents. The Society for Immunotherapy of Cancer (SITC) convened a panel of experts to develop this clinical practice guideline on immunotherapy for the treatment of melanoma, including rare subtypes of the disease (eg, uveal, mucosal), with the goal of improving patient care by providing guidance to the oncology community. Drawing from published data and clinical experience, the Expert Panel developed evidence- and consensus-based recommendations for healthcare professionals using immunotherapy to treat melanoma, with topics including therapy selection in the advanced and perioperative settings, intratumoral immunotherapy, when to use immunotherapy for patients with BRAFV600-mutated disease, management of patients with brain metastases, evaluation of treatment response, special patient populations, patient education, quality of life, and survivorship, among others.

PET-CT underestimates the true pathological extent of disease at lymphadenectomy for melanoma patients after systemic therapy

INTRODUCTION

Modern systemic therapy has revolutionized the treatment of melanoma. Currently, patients with clinically involved lymph nodes require lymphadenectomy with associated morbidities. Positron Emission Tomography - Computed Tomography (PET-CT) has demonstrated accuracy in melanoma detection and response to therapy. We aimed to identify whether a PET-CT directed lymphatic resection after systemic therapy is oncologically sound.

MATERIALS AND METHODS

Retrospective review of patients who underwent lymphadenectomy after systemic therapy for melanoma with a preoperative PET-CT. Examined demographic, clinical, and perioperative parameters including extent of disease, systemic therapy and response, and PET-CT findings compared to pathological outcomes. We compared patients with "as or less than expected" outcomes on pathology against those with "more than expected" pathological outcomes.

RESULTS

Thirty-nine patients met inclusion criteria. In 28 (71.8%), pathological outcomes were "as or less than expected" by PET-CT, and in 11 (28.2%) pathological outcome were "more than expected". "More than expected" occurred more frequently with advanced disease at presentation with 75% presenting with regional/metastatic disease versus only 42.9% in the "as or less than expected" group (p = 0.015). Poor response to therapy also trended towards the "more than expected" group with only 27.3% favorable response versus 53.6% favorable response in the "as or less than expected" group, not statistically significant. Extent of disease on imaging failed to predict pathological concordance.

CONCLUSION

PET-CT underestimates pathological extent of disease in the lymphatic basin in 30% of patients after systemic therapy. We failed to identify predictors of more extensive disease and warn against limited PET-CT directed lymphatic resections.

Complete pathological response after chemotherapy or immune checkpoint inhibitors in deficient MMR metastatic colorectal cancer: Results of a retrospective multicenter study

About 5% of the patients with metastatic colorectal cancers (mCRC) present microsatellite instability (MSI)/deficient mismatch repair system (dMMR). While metastasectomy is known to improve overall and progression-free survival in mCRC, specific results in selected patients with dMMR/MSI mCRC are lacking. Our study aimed to describe metastasectomy results, characterize histological response and evaluate pathological complete response (pCR) rate in patients with dMMR/MSI mCRC. We retrospectively reviewed data from all consecutive patients with dMMR/MSI mCRC who underwent surgical metastasectomy between January 2010 and June 2021 in 17 French centers. Primary outcome was to assess the pCR rate defined by tumor regression grade (TRG) 0. Secondary endpoints included relapse-free survival (RFS) and overall survival (OS), and explored TRG as predictive factor for RFS and OS. Among the 88 patients operated, 109 metastasectomies were performed in 81 patients after neoadjuvant treatment [chemotherapy ± targeted therapy (CTT): 69, 85.2%; immunotherapy (ICI): 12, 14.8%], and pCR was achieved in 13 (16.1%) patients. Among the latter, pCR rate were 10.2% in the patients having received CTT (N = 7) and 50.0% in the patients treated with ICI (N = 6). Radiological response did not predict TRG. With a median follow-up of 57.9 (IQR 34.2-81.6) months, median RFS was 20.2 (15.4-not reached) months, median OS was not reached. Major pathological responses (TRG0 + TRG1) were significantly associated with longer RFS (HR 0.12, 95% CI 0.03-0.55; P = .006). The pCR rate of 16.1% achieved with neoadjuvant treatment in patients with dMMR/MSI mCRC is consistent with previously reported rates in pMMR/MSS mCRC. Immunotherapy showed better pCR rate than chemotherapy ± targeted therapy. Further prospective trials are needed to validate immunotherapy as neoadjuvant treatment in resectable/potentially resectable dMMR/MSI mCRC and identify predictive factors for pCR.

Protracted complete response after limited checkpoint inhibitor dosing: A case report

Immunotherapy is an important modality in the treatment of many types of malignancy. The optimal duration of treatment with immunotherapy in patients with metastatic malignancies who experience complete responses is not fully understood. Our case demonstrates a protracted complete response in a patient with metastatic gastric adenocarcinoma after just three doses of pembrolizumab. This illustrates a need for further research into which patients might have responses such as these and could therefore be spared additional doses of an expensive treatment with many potential side effects.

Cured or Not? Long-term Outcomes of Immunotherapy Responders. Focus on Melanoma

PURPOSE OF REVIEW

Immune checkpoint inhibitors (ICIs) demonstrated robust antitumor activity and tolerable safety in advanced melanoma. Data on long-term outcome of patients who benefited from this therapy and who are still free of progression despite ICI discontinuation is now available. We review here the characteristics of long-term ICI responders and address the critical question of cure.

RECENT FINDINGS

Long-term outcome of patients with metastatic melanoma enrolled in large phase 2 and phase 3 clinical trials evaluating ICI in metastatic melanoma is now available. Durable responses, with more than 6 years of median follow-up, may persist after discontinuation. They occur more frequently in patients who achieved a complete response rather than in patients who had partial response or stable disease. Although long-term clinical benefit is more frequent in patients with high PDL-1 expression and smaller tumor burden, durable response may also be observed regardless of baseline characteristics. In patients with asymptomatic brain metastasis, combined immunotherapy (ipilimumab plus nivolumab) may also lead to long-term remission. Clinical trials confirm the durable antitumor activity of ICI. Although the hope for cure seems reasonable for many patients in this situation, late relapses may occur and no relapse-predictive biomarkers have been identified yet. Long-term responders who relapse can respond to a rechallenge of ICI although data are limited concerning the rate and the duration of this new response.

Characteristics and outcomes of advanced melanoma patients with complete response and elective discontinuation of first-line anti-programmed death-1 monotherapy: A real-world multicentre observational cohort study

Anti-programmed death-1 (anti-PD1) treatment has significantly improved outcomes of advanced melanoma with a considerable percentage of patients achieving complete response (CR). This real-world study analyzed the feasibility of elective anti-PD1 discontinuation in advanced melanoma patients with CR and evaluated factors related to sustained response. Thirty-five patients with advanced cutaneous or primary unknown melanoma with CR to nivolumab or pembrolizumab from 11 centers were included. Mean age was 66.5 years, and 97.1% had ECOG PS 0-1. 28.6% had ≥3 metastatic sites with 58.8% having M1a-M1b disease; 8.6% had liver and 5.7% had brain metastases. At baseline, 80% had normal LDH, and 85.7% had a neutrophil-to-lymphocyte ratio ≤3. 74.3% of patients had CR confirmed in PET-CT. Median duration of anti-PD1 was 23.4 months (range 1.3-50.5). 24 months after therapy discontinuation, 91.9% of patients were progression-free. Estimated PFS and OS at 36, 48, and 60 months from the start of anti-PD1 were 94.2%, 89.9%, 84.3%, and 97.1%, 93.3%, 93.3%, respectively. Antibiotics use after anti-PD1 discontinuation increased the odds of progression (OR 16.53 [95% CI 1.7, 226.03]). The study confirms the feasibility of elective anti-PD1 discontinuation in advanced melanoma patients with CR and favorable prognostic factors at baseline.

Discontinuation of anti-PD1 in advanced melanoma: an observational retrospective study from the Italian Melanoma Intergroup

BACKGROUND

Immunotherapy has improved the survival of patients with stage IV melanoma. In responders, clinical benefits may be long-lasting and persist even after treatment discontinuation. The optimal duration of anti-PD1 (anti-Programmed cell death-1) therapy in metastatic melanoma patients remains to be elucidated. Moreover, limited data are available on clinical outcomes of patients that discontinued anti-PD1 immunotherapy in a real-life setting. The aim of this study was to evaluate the progression-free survival (PFS) in patients with metastatic melanoma who interrupted anti-PD-1 treatment in the in the absence of disease progression.

METHODS

We retrospectively reviewed patients with advanced/metastatic melanoma treated with anti-PD1 immunotherapy at 23 Italian Melanoma Intergroup (IMI) centres. The study investigated the risk of relapse in patients who stopped anti-PD1 therapy due to CR (Complete response), treatment-related toxicity, or by their own choice after a long period of treatment. Clinical and biological factors associated with or without recurrence were evaluated.

RESULTS

The study population included 237 patients. The median age of patients was 68.9 years (standard deviation: 13; range 33-95). The median time on treatment was 33 months (standard deviation: 18, 7; range 1-98). Among the 237 patients, 128 (54%) interrupted the anti-PD1 for CR, 74 patients (31.2%) for adverse events (37 patients in CR, 27 patients in partial response (PR), ten patients in stable disease (SD), and 35 patients (14.8%) by their own choice (12 patients in CR, 17 patients in PR, and 6 patients in SD). After a mean follow-up of 21 months (range 1-81), PFS after anti-PD1 discontinuation was 85.7%. Thirty-four patients (14.3%) developed disease progression after a median of 12 months (range 1-35): ten patients (29.4%) after discontinuation in CR, 17 patients (50%) after discontinuation for treatment-related toxicity (seven in CR, five in PR, five in SD), and seven (20.6%) after discontinuation due to the patient's decision (two in CR, four in PR, one in SD). Only 7.8% of patients who interrupted in CR (10/128), along with 23% of patients who interrupted for limiting toxicity (17/74) and 20% of patients who interrupted by their own choice (7/35), developed recurrence. Regarding patients who discontinued therapy because of CR, we observed a negative association between recurrence and site of primary melanoma, especially mucosal sites (p = <0.05, HR (Hazard ratio) 15.57 IC (confidence interval) 95% 2.64-91.73). Moreover, M1b patients who achieved a CR showed a lower number of relapses (p = <0.05, HR 3.84 IC 95% 1.40-8.48).

CONCLUSIONS

This study shows in a real-life setting that, with anti-PD-1 therapy, long-lasting responses, can be maintained after anti-PD1 interruption. In 70.6% of cases, recurrences were observed among patients who did not obtain a CR at treatment discontinuation.

Short-course treatment after complete response to pembrolizumab in metastatic urothelial bladder cancer: a case series

Background: The optimal duration of treatment for metastatic patients who achieve a complete response with immune checkpoint inhibitors is unknown. Methods: The outcome for six metastatic bladder cancer patients who received short course of pembrolizumab is reported. Results: A median number of seven cycles of pembrolizumab was given. After a median follow-up of 38 months, progressive disease was confirmed in three patients. All patients relapsed in lymph nodes and underwent pembrolizumab rechallenge: one achieved a complete response, another a partial response. Conclusion: Our case series paves the way for discontinuation of pembrolizumab in patients who achieve a complete response since three out of six patients remain free of disease after 3-year follow-up. Prospective studies are required to confirm our results.

[18F]FDG PET/CT in the Evaluation of Melanoma Patients Treated with Immunotherapy

Immunotherapy is based on manipulation of the immune system in order to act against tumour cells, with growing evidence especially in melanoma patients. The challenges faced by this new therapeutic tool are (i) finding valid evaluation criteria for response assessment; (ii) knowing and distinguishing between "atypical" response patterns; (iii) using PET biomarkers as predictive and response evaluation parameters and (iv) diagnosis and management of immunorelated adverse effects. This review is focused on melanoma patients analysing (a) the role of [18F]FDG PET/CT in the mentioned challenges; (b) the evidence of its efficacy. For this purpose, we performed a review of the literature, including original and review articles. In summary, although there are no clearly established or globally accepted criteria, modified response criteria are potentially appropriate for evaluation of immunotherapy benefit. In this context, [18F]FDG PET/CT biomarkers appear to be promising parameters in prediction and assessment of response to immunotherapy. Moreover, immunorelated adverse effects are recognized as predictors of early response to immunotherapy and may be associated with better prognosis and clinical benefit.

FDG PET/CT Prognostic Markers in Patients with Advanced Melanoma Treated with Ipilimumab and Nivolumab

Background Despite improved response to combined ipilimumab and nivolumab (hereafter, IpiNivo) treatment for advanced melanoma, many patients exhibit primary or acquired resistance. This, combined with high risk of immune-related adverse events, makes identifying markers predictive of outcomes desirable. Purpose To investigate the prognostic value of fluorine 18 (¹⁸F) fluorodeoxyglucose (FDG) PET/CT parameters at baseline and as part of response monitoring in patients with advanced melanoma undergoing IpiNivo treatment. Materials and Methods This was a single-center retrospective study of adult patients with melanoma who received IpiNivo. Baseline FDG PET/CT parameters that included metabolic tumor volume (MTV), tumor stage, mutation status, Eastern Cooperative Oncology Group performance score, lactate dehydrogenase level, and treatment line were correlated with overall survival in univariable and multivariable Cox regression analyses. Treatment response as determined with FDG PET/CT was correlated with overall survival. Results In total, 122 patients (median age, 61 years [IQR, 51-69 years]; 89 men) were included; 78% (95 of 122) had an Eastern Cooperative Oncology Group score of 0, 52% (45 of 86) had an elevated lactate dehydrogenase level, 39% (48 of 122) had a metastatic stage of M1c and 45% (55 of 122) M1d, 45% (55 of 122) had BRAF V600E/K mutation, and the median MTV was 42 mL. Patients with a higher than median MTV at baseline FDG PET/CT had a lower 12-month survival rate compared with those with a lower than median MTV (43% [95% CI: 32, 58] vs 66% [95% CI: 55, 79], P < .001). In multivariable analysis, higher versus lower than median MTV, Eastern Cooperative Oncology Group performance scores of 1-2 versus 0, and subsequent versus first-line IpiNivo treatment were independently associated with overall survival (hazard ratio [HR]: 1.68 [95% CI: 1.02, 2.78], P = .04; 3.1 [95% CI: 1.8, 5.4], P < .001; and 11.2 [95% CI: 3.4, 37.1], P = .002, respectively). The 12-month overall survival rate was lower in patients with progressive disease than in those without progression (35% [95% CI: 24, 51] vs 90% [95% CI: 83, 99]; HR, 7.3 [95% CI: 3.9, 13.3]; P < .001). Conclusion Baseline fluorine 18 fluorodeoxyglucose PET/CT metabolic tumor volume was an independent prognostic marker in patients with advanced melanoma who received ipilimumab and nivolumab treatment. © RSNA, 2023 Supplemental material is available for this article.

Novelties from the Joint EANM/SNMMI/ANZSNM Guidelines on Immunotherapy

In the past decade, the implementation of immunotherapy with checkpoint inhibitors has determined a major change in the management of oncological patients. The challenges associated to the new therapeutic regimen have promoted adapted criteria for response assessment to interpret imaging findings and atypical patterns of response. Parallel to the new morphological criteria, also ¹⁸fluoro-deoxyglucose positron emission/computed tomography imaging has required novel approaches and specific guidelines on how to perform, interpret, and report the scan in patients with solid tumors under immune checkpoint inhibitors therapy. A summary of the novelties related to the new joint international European Association of Nuclear Medicine (EANM)/Society of Nuclear Medicine and Molecular Imaging (SNMMI)/Australian and New Zealand Society of Nuclear Medicine (ANZSNM) guidelines on immunotherapy is provided herein to elucidate most critical aspects in image interpretation.

What is the optimal duration of immune checkpoint inhibitors in malignant tumors?

Immunotherapy, represented by immune checkpoint inhibitors (ICIs), has made a revolutionary difference in the treatment of malignant tumors, and considerably extended patients' overall survival (OS). In the world medical profession, however, there still reaches no clear consensus on the optimal duration of ICIs therapy. As reported, immunotherapy response patterns, immune-related adverse events (irAEs) and tumor stages are all related to the diversity of ICIs duration in previous researches. Besides, there lacks clear clinical guidance on the intermittent or continuous use of ICIs. This review aims to discuss the optimal duration of ICIs, hoping to help guide clinical work based on the literature.

Association of Pathologic Complete Response and Long-Term Survival Outcomes Among Patients Treated With Neoadjuvant Chemotherapy or Chemoradiotherapy for NSCLC: A Meta-Analysis

Introduction

Increased efforts to optimize outcomes for early stage NSCLC through the investigation of novel perioperative treatment strategies are ongoing. An emerging question is the role of pathologic response and its association with long-term clinical outcomes after neoadjuvant therapy.

Methods

To investigate the association of pathologic complete response (pCR) and event-free survival (EFS) and overall survival (OS), we performed a systematic review and meta-analysis identifying studies reporting on the prognostic impact of pCR after neoadjuvant chemotherapy or chemoradiotherapy. To evaluate this prognostic value, an aggregated data (AD) meta-analyses was conducted to estimate the pooled hazard ratios (HRs) of EFS and OS for pCR. Using reconstructed individual patient data (IPD), pooled Kaplan-Meier curves were obtained to estimate this association in a more granular fashion. Subgroup analyses were conducted to further explore the impacts of study-level characteristics.

Results

A total of 28 studies comprising 7011 patients were included in the AD meta-analysis, of which, IPD was available for 6274 patients from 24 studies. Results from our AD meta-analysis revealed a pooled pCR rate of 18% (95% confidence interval [CI]: 15%–21%), including significant improvements in OS (HR = 0.50, 95% CI: 0.45–0.56) and EFS (HR = 0.46, 95% CI: 0.37–0.57) on the basis of pCR status. Our IPD analysis revealed a 5-year OS rate of 63% (95% CI: 59.6–67.4) for patients with a pCR compared with 39% (95% CI: 34.5–44.5) for those without a pCR.

Conclusions

pCR after neoadjuvant chemotherapy plus or minus radiotherapy is associated with significant improvements in EFS and survival for patients with resectable NSCLC.

MRI techniques for immunotherapy monitoring

MRI is a widely available clinical tool for cancer diagnosis and treatment monitoring. MRI provides excellent soft tissue imaging, using a wide range of contrast mechanisms, and can non-invasively detect tissue metabolites. These approaches can be used to distinguish cancer from normal tissues, to stratify tumor aggressiveness, and to identify changes within both the tumor and its microenvironment in response to therapy. In this review, the role of MRI in immunotherapy monitoring will be discussed and how it could be utilized in the future to address some of the unique clinical questions that arise from immunotherapy. For example, MRI could play a role in identifying pseudoprogression, mixed response, T cell infiltration, cell tracking, and some of the characteristic immune-related adverse events associated with these agents. The factors to be considered when developing MRI imaging biomarkers for immunotherapy will be reviewed. Finally, the advantages and limitations of each approach will be discussed, as well as the challenges for future clinical translation into routine clinical care. Given the increasing use of immunotherapy in a wide range of cancers and the ability of MRI to detect the microstructural and functional changes associated with successful response to immunotherapy, the technique has great potential for more widespread and routine use in the future for these applications.

Monitoring of Current Cancer Therapy by Positron Emission Tomography and Possible Role of Radiomics Assessment

Evaluation of cancer therapy with imaging is crucial as a surrogate marker of effectiveness and survival. The unique response patterns to therapy with immune-checkpoint inhibitors have facilitated the revision of response evaluation criteria using FDG-PET, because the immune response recalls reactive cells such as activated T-cells and macrophages, which show increased glucose metabolism and apparent progression on morphological imaging. Cellular metabolism and function are critical determinants of the viability of active cells in the tumor microenvironment, which would be novel targets of therapies, such as tumor immunity, metabolism, and genetic mutation. Considering tumor heterogeneity and variation in therapy response specific to the mechanisms of therapy, appropriate response evaluation is required. Radiomics approaches, which combine objective image features with a machine learning algorithm as well as pathologic and genetic data, have remarkably progressed over the past decade, and PET radiomics has increased quality and reliability based on the prosperous publications and standardization initiatives. PET and multimodal imaging will play a definitive role in personalized therapeutic strategies by the precise monitoring in future cancer therapy.

Molecular imaging to support cancer immunotherapy

The advent of immune checkpoint inhibitors has reinvigorated the field of immuno-oncology. These monoclonal antibody-based therapies allow the immune system to recognize and eliminate malignant cells. This has resulted in improved survival of patients across several tumor types. However, not all patients respond to immunotherapy therefore predictive biomarkers are important. There are only a few Food and Drug Administration-approved biomarkers to select patients for immunotherapy. These biomarkers do not consider the heterogeneity of tumor characteristics across lesions within a patient. New molecular imaging tracers allow for whole-body visualization with positron emission tomography (PET) of tumor and immune cell characteristics, and drug distribution, which might guide treatment decision making. Here, we summarize recent developments in molecular imaging of immune checkpoint molecules, such as PD-L1, PD-1, CTLA-4, and LAG-3. We discuss several molecular imaging approaches of immune cell subsets and briefly summarize the role of FDG-PET for evaluating cancer immunotherapy. The main focus is on developments in clinical molecular imaging studies, next to preclinical studies of interest given their potential translation to the clinic.

Joint EANM/SNMMI/ANZSNM practice guidelines/procedure standards on recommended use of [18F]FDG PET/CT imaging during immunomodulatory treatments in patients with solid tumors version 1.0

PURPOSE

The goal of this guideline/procedure standard is to assist nuclear medicine physicians, other nuclear medicine professionals, oncologists or other medical specialists for recommended use of [18F]FDG PET/CT in oncological patients undergoing immunotherapy, with special focus on response assessment in solid tumors.

METHODS

In a cooperative effort between the EANM, the SNMMI and the ANZSNM, clinical indications, recommended imaging procedures and reporting standards have been agreed upon and summarized in this joint guideline/procedure standard.

CONCLUSIONS

The field of immuno-oncology is rapidly evolving, and this guideline/procedure standard should not be seen as definitive, but rather as a guidance document standardizing the use and interpretation of [18F]FDG PET/CT during immunotherapy. Local variations to this guideline should be taken into consideration.

PREAMBLE

The European Association of Nuclear Medicine (EANM) is a professional non-profit medical association founded in 1985 to facilitate worldwide communication among individuals pursuing clinical and academic excellence in nuclear medicine. The Society of Nuclear Medicine and Molecular Imaging (SNMMI) is an international scientific and professional organization founded in 1954 to promote science, technology and practical application of nuclear medicine. The Australian and New Zealand Society of Nuclear Medicine (ANZSNM), founded in 1969, represents the major professional society fostering the technical and professional development of nuclear medicine practice across Australia and New Zealand. It promotes excellence in the nuclear medicine profession through education, research and a commitment to the highest professional standards. EANM, SNMMI and ANZSNM members are physicians, technologists, physicists and scientists specialized in the research and clinical practice of nuclear medicine. All three societies will periodically put forth new standards/guidelines for nuclear medicine practice to help advance the science of nuclear medicine and improve service to patients. Existing standards/guidelines will be reviewed for revision or renewal, as appropriate, on their fifth anniversary or sooner, if indicated. Each standard/guideline, representing a policy statement by the EANM/SNMMI/ANZSNM, has undergone a thorough consensus process, entailing extensive review. These societies recognize that the safe and effective use of diagnostic nuclear medicine imaging requires particular training and skills, as described in each document. These standards/guidelines are educational tools designed to assist practitioners in providing appropriate and effective nuclear medicine care for patients. These guidelines are consensus documents based on current knowledge. They are not intended to be inflexible rules or requirements of practice, nor should they be used to establish a legal standard of care. For these reasons and those set forth below, the EANM, SNMMI and ANZSNM caution against the use of these standards/guidelines in litigation in which the clinical decisions of a practitioner are called into question. The ultimate judgment regarding the propriety of any specific procedure or course of action must be made by medical professionals considering the unique circumstances of each case. Thus, there is no implication that an action differing from what is laid out in the guidelines/procedure standards, standing alone, is below standard of care. To the contrary, a conscientious practitioner may responsibly adopt a course of action different from that set forth in the standards/guidelines when, in the reasonable judgment of the practitioner, such course of action is indicated by the condition of the patient, limitations of available resources or advances in knowledge or technology subsequent to publication of the guidelines/procedure standards. The practice of medicine involves not only the science, but also the art of dealing with the prevention, diagnosis, alleviation and treatment of disease. The variety and complexity of human conditions make it impossible for general guidelines to consistently allow for an accurate diagnosis to be reached or a particular treatment response to be predicted. Therefore, it should be recognized that adherence to these standards/ guidelines will not ensure a successful outcome. All that should be expected is that practitioners follow a reasonable course of action, based on their level of training, current knowledge, clinical practice guidelines, available resources and the needs/context of the patient being treated. The sole purpose of these guidelines is to assist practitioners in achieving this objective. The present guideline/procedure standard was developed collaboratively by the EANM, the SNMMI and the ANZSNM, with the support of international experts in the field. They summarize also the views of the Oncology and Theranostics and the Inflammation and Infection Committees of the EANM, as well as the procedure standards committee of the SNMMI, and reflect recommendations for which the EANM and SNMMI cannot be held responsible. The recommendations should be taken into the context of good practice of nuclear medicine and do not substitute for national and international legal or regulatory provisions.

Quantitative imaging biomarkers of immune-related adverse events in immune-checkpoint blockade-treated metastatic melanoma patients: a pilot study

PURPOSE

To develop quantitative molecular imaging biomarkers of immune-related adverse event (irAE) development in malignant melanoma (MM) patients receiving immune-checkpoint inhibitors (ICI) imaged with 18F-FDG PET/CT.

METHODS

18F-FDG PET/CT images of 58 MM patients treated with anti-PD-1 or anti-CTLA-4 ICI were retrospectively analyzed for indication of irAE. Three target organs, most commonly affected by irAE, were considered: bowel, lung, and thyroid. Patient charts were reviewed to identify which patients experienced irAE, irAE grade, and time to irAE diagnosis. Target organs were segmented using a convolutional neural network (CNN), and novel quantitative imaging biomarkers - SUV percentiles (SUVX%) of 18F-FDG uptake within the target organs - were correlated with the clinical irAE status. Area under the receiver-operating characteristic curve (AUROC) was used to quantify irAE detection performance. Patients who did not experience irAE were used to establish normal ranges for target organ 18F-FDG uptake.

RESULTS

A total of 31% (18/58) patients experienced irAE in the three target organs: bowel (n=6), lung (n=5), and thyroid (n=9). Optimal percentiles for identifying irAE were bowel (SUV95%, AUROC=0.79), lung (SUV95%, AUROC=0.98), and thyroid (SUV75%, AUROC=0.88). Optimal cut-offs for irAE detection were bowel (SUV95%>2.7 g/mL), lung (SUV95%>1.7 g/mL), and thyroid (SUV75%>2.1 g/mL). Normal ranges (95% confidence interval) for the SUV percentiles in patients without irAE were bowel [1.74, 2.86 g/mL], lung [0.73, 1.46 g/mL], and thyroid [0.86, 1.99 g/mL].

CONCLUSIONS

Increased 18F-FDG uptake within irAE-affected organs provides predictive information about the development of irAE in MM patients receiving ICI and represents a potential quantitative imaging biomarker for irAE. Some irAE can be detected on 18F-FDG PET/CT well before clinical symptoms appear.

Imaging immunity in patients with cancer using positron emission tomography

Immune checkpoint inhibitors and related molecules can achieve tumour regression, and even prolonged survival, for a subset of cancer patients with an otherwise dire prognosis. However, it remains unclear why some patients respond to immunotherapy and others do not. PET imaging has the potential to characterise the spatial and temporal heterogeneity of both immunotherapy target molecules and the tumor immune microenvironment, suggesting a tantalising vision of personally-adapted immunomodulatory treatment regimens. Personalised combinations of immunotherapy with local therapies and other systemic therapies, would be informed by immune imaging and subsequently modified in accordance with therapeutically induced immune environmental changes. An ideal PET imaging biomarker would facilitate the choice of initial therapy and would permit sequential imaging in time-frames that could provide actionable information to guide subsequent therapy. Such imaging should provide either prognostic or predictive measures of responsiveness relevant to key immunotherapy types but, most importantly, guide key decisions on initiation, continuation, change or cessation of treatment to reduce the cost and morbidity of treatment while enhancing survival outcomes. We survey the current literature, focusing on clinically relevant immune checkpoint immunotherapies, for which novel PET tracers are being developed, and discuss what steps are needed to make this vision a reality.

Representativeness of the Index Lymph Node for Total Nodal Basin in Pathologic Response Assessment After Neoadjuvant Checkpoint Inhibitor Therapy in Patients With Stage III Melanoma

IMPORTANCE

Neoadjuvant checkpoint inhibition in patients with high-risk stage III melanoma shows high pathologic response rates associated with a durable relapse-free survival. Whether a therapeutic lymph node dissection (TLND) can be safely omitted when a major pathologic response in the largest lymph node metastasis at baseline (index lymph node; ILN) is obtained is currently being investigated. A previous small pilot study (n = 12) showed that the response in the ILN may be representative of the pathologic response in the entire TLND specimen.

OBJECTIVE

To assess the concordance of response between the ILN and the total lymph node bed in a larger clinical trial population.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective pathologic response analysis of a multicenter clinical trial population of patients from the randomized Study to Identify the Optimal Adjuvant Combination Scheme of Ipilimumab and Nivolumab in Melanoma Patients (OpACIN) and Optimal Neo-Adjuvant Combination Scheme of Ipilimumab and Nivolumab (OpACIN-neo) trials. Included patients were treated with 6 weeks neoadjuvant ipilimumab plus nivolumab. Patient inclusion into the trials was conducted from August 12, 2015, to October 24, 2016 (OpACIN), and November 24, 2016, and June 28, 2018 (OpACIN-neo). Data were analyzed from April 1, 2020, to August 31, 2021.

MAIN OUTCOMES AND MEASURES

Concordance of the pathologic response between the ILN and the TLND tumor bed. The pathologic response of the ILN was retrospectively assessed according to the International Neoadjuvant Melanoma Consortium criteria and compared with the pathologic response of the entire TLND specimen.

RESULTS

A total of 82 patients treated with neoadjuvant ipilimumab and nivolumab followed by TLND (48 [59%] were male; median age, 58.5 [range, 18-80] years) were included. The pathologic response in the ILN was concordant with the entire TLND specimen response in 81 of 82 patients (99%) and in 79 of 82 patients (96%) concordant when comparing the ILN response with the response in every individual lymph node. In the single patient with a discordant response, the ILN response (20% viable tumor, partial pathologic response) underestimated the entire TLND specimen response (5% viable, near-complete pathologic response). Two other patients each had 1 small nonindex node that contained 80% viable tumor (pathologic nonresponse) whereas all other lymph nodes (including the ILN) showed a partial pathologic response. In these 2 patients, the risk of regional relapse might potentially have been increased if TLND had been omitted.

CONCLUSIONS AND RELEVANCE

The results of this study suggest that the pathologic response of the ILN may be considered a reliable indicator of the entire TLND specimen response and may support the ILN response-directed omission of TLND in a prospective trial.

Monitoring of Programmed Cell Death Ligand-1 Blockade Using FDG PET/CT for Microsatellite Instability-High Metastatic Breast Cancer

ABSTRACT

Microsatellite instability-high/mismatch repair deficiency is one of biomarkers predicting the response to pembrolizumab, an immune checkpoint inhibitor for metastatic solid tumors. A 44-year-old woman with stage IIIC right breast cancer was treated with mastectomy and axillary node dissection after primary systemic chemotherapy followed by radiation, chemotherapy, and hormonal therapy. Eighteen months after surgery, recurrent diseases were revealed and refractory to multiple treatments. The recurrent site biopsy showed microsatellite instability-high, and programmed cell death ligand-1 inhibitor pembrolizumab was administrated. FDG PET/CT showed complete metabolic response over 12 months and is useful to monitor the response of active immunotherapy.

Metabolic imaging with FDG-PET and time to progression in patients discontinuing immune-checkpoint inhibition for metastatic melanoma

Background

The optimal duration of immune checkpoint blockade (ICB) therapy is not well established. Active residual disease is considered prohibitive for treatment discontinuation and its detection by diagnostic CT imaging is limited. Here, we set out to determine the potential added value of 2-[18F]fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) to identify patients at higher risk of relapse following discontinuation of ICB in advanced melanoma.

Methods

Metastatic melanoma patients who discontinued ICB were identified retrospectively. Eligible patients received FDG-PET and diagnostic CT within four months of ICB discontinuation. We defined morphologic response using RECIST v1.1. Complete metabolic response (CMR) was defined as uptake in tumor lesions below background, whereas any site of residual, FDG-avid disease was rated as non-CMR. The primary endpoint was time to progression (TTP) after therapy discontinuation stratified by morphologic and metabolic imaging response using Kaplan–Meier estimates and log-rank test.

Results

Thiry-eight patients were eligible for this analysis. Median follow-up was 37.3 months since ICB discontinuation. Median TTP in the overall cohort was not reached. A greater proportion of patients were rated as CMR in PET (n = 34, 89.5%) as compared to complete response (CR) in CT (n = 13, 34.2%). Median TTP was reached in patients with non-CMR (12.7 months, 95%CI 4.4-not reached) but not for patients with CMR (log-rank: p < 0.001). All patients with complete response by CT had CMR by PET. In a subset of patients excluding those with complete response by CT, TTP remained significantly different between CMR and non-CMR (log-rank: p < 0.001).

Conclusion

Additional FDG-PET at time of discontinuation of ICB therapy helps identify melanoma patients with a low risk of recurrence and favourable prognosis compared to CT imaging alone. Results may have clinical relevance especially for patients with residual tumor burden.

Sensitivity of treatment-free survival to subgroup analyses in patients with advanced melanoma treated with immune checkpoint inhibitors

Patients with advanced melanoma treated with immune checkpoint inhibitors can experience ongoing disease control after treatment discontinuation without subsequent systemic anticancer therapy. We previously defined a novel outcome, treatment-free survival (TFS), as the time between protocol therapy cessation and subsequent therapy initiation/death. We assessed the effect of established prognostic variables [lactate dehydrogenase (LDH), programmed death ligand 1 status, BRAF mutation status, performance status, and sex] on TFS in different treatment scenarios: treatment until toxicity/progression with frequent early cessation (nivolumab plus ipilimumab), treatment until toxicity/progression with a well-tolerated regimen (nivolumab), and treatment for a short fixed duration (ipilimumab). Data were pooled from 1077 patients with advanced melanoma treated in the CheckMate 069 and 067 trials. TFS was defined as the area between the Kaplan-Meier curves for time to therapy cessation and time to subsequent therapy initiation/death. TFS was estimated by restricted mean (r-mean) survival time at 36 months since randomization. Clinically meaningful TFS (r-mean TFS 3.7-12.7 months) was observed across all patient subgroups. TFS was longest in patients treated with nivolumab plus ipilimumab. The largest differences in r-mean TFS were observed with LDH in the nivolumab plus ipilimumab and ipilimumab treatment groups (TFS difference 4.7 and 4.9 months, respectively). In the nivolumab group, there was little difference in TFS across subgroups (r-mean TFS 3.7-5.5 months). TFS was sensitive to prognostic subgroup differences; however, duration of treatment affected the sensitivity of TFS. These results provide further support for TFS as a clinical outcome measure.

Visual Assessment of 18F-FDG Uptake on PET to Predict Survival Benefit to PD-1 Blockade in Non-Small Cell Lung Cancer

BACKGROUND

Programmed death 1 (PD-1) blockade is a standard treatment for patients with metastatic non-small cell lung cancer (NSCLC). Approximately 20% patients receiving PD-1 blockade monotherapy can survive for more than 5 years. However, there are limited data on the optimal biomarkers for predicting long-term outcomes. Therefore, this study aimed to evaluate the prognostic significance of 18F-FDG uptake in patients with NSCLC responding to PD-1 blockade.

PATIENTS AND METHODS

Thirty-eight patients with advanced NSCLC who underwent 18F-FDG PET after confirmation of clinical response to PD-1 blockade monotherapy were retrospectively included in this study. Visual assessment using a 5-point scale score according to 18F-FDG uptake was performed, and the 18F-FDG uptake cutoff score for prolonged response to PD-1 blockade was defined as 3 (low score: 1, 2, or 3 and high score: 4 or 5).

RESULTS

A significantly greater number of patients with low scores had a performance status of 0 or 1 than patients with high scores. Among the 38 patients, 20 (53%) had a low score and 18 (47%) had a high score. Progression-free survival and overall survival were significantly longer in patients with low scores than in patients with high scores. Low 18F-FDG uptake was an independent prognostic factor for predicting favorable progression-free survival and overall survival, as confirmed by multivariate analysis.

CONCLUSIONS

Tumors with lower 18F-FDG uptake on PET than normal hepatic lesions exhibit the possibility of prolonged response to PD-1 blockade. Visual assessment on PET is easy for every clinician and is understandable to confirm aggressive tumor activity.

Clinical value of routine FDG-PET scans as a decision tool for early immunotherapy discontinuation in advanced melanoma

Routine [18F]2-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) may help predict clinical outcomes after response to immunotherapy. With an EMA-recommended treatment length until disease progression or unacceptable toxicity, the optimal duration of immunotherapy is still to be defined. In a retrospective study, we retrieved from the Danish Metastatic Melanoma Database (DAMMED), all patients that were annotated as a partial or complete response based on the computed tomography (CT) of serial FDG-PET-CT scans. Patients treated with an anti-PD-1-containing regimen for <18 months and ≥4 months without disease progression after halting anti-PD-1 were included. Cases were divided into an "elective" and a "toxicity" group based on the reason for treatment discontinuation. A total of 140 patients were included. At 29.3 months of median follow up, a higher proportion of patients remained alive in the "elective" group (93% vs 75%, p=0.0031) with an improved melanoma-specific (HR 0.07, 95% CI 0.02-0.32, p=0.0041) survival (MSS). Patients without FDG-avid lesions at the time of treatment discontinuation had an improved MSS (HR 0.03, 95% CI 0.01-0.17, p=0.0002), and the absence of FDG-avid lesions was the only independent predictive feature of improved MSS in multivariate analysis. In conclusion, patients with metastatic melanoma who obtain an early response and early discontinue immunotherapy have an excellent prognosis, especially in the absence of FDG-PET avid lesions when discontinuing treatment. These data support the option of early discontinuation, limiting possible over-treatment and thereby toxicity, health, and economic expenses and improving logistics. This article is protected by copyright. All rights reserved.

Feasibility, acceptability, and utility of a nurse-led survivorship program for people with metastatic melanoma (MELCARE)

PURPOSE

Immune checkpoint inhibitors (ICIs) and targeted therapy (TT) have improved the survival of people with metastatic melanoma. We assessed the feasibility, acceptability, and utility of a novel model of nurse-led, telehealth-delivered survivorship care (MELCARE) for this survivor group.

METHODS

People ≥ 18 years diagnosed with unresectable stage III or stage IV melanoma who were ≥ 6 months post initiation of ICI/TT with a radiological response suggestive of a long-term response to ICI/TT were recruited from a specialist melanoma centre in Australia. All participants received MELCARE, a nurse-led survivorship program involving two telehealth consultations 3 months apart, needs assessment using the Distress Thermometer (DT) and Problem List, and creation of a survivorship care plan. Feasibility, acceptability, and utility were assessed using rates of consent and study completion, time taken to complete each component of MELCARE, the Acceptability of Intervention Measure (AIM), and a customised utility survey.

RESULTS

31/54 (57%) people consented. Participants were male (21, 68%), with a median age of 67 (range: 46-82). Eleven (35%) were receiving/had received ipilimumab and nivolumab and 27 (87%) had ceased treatment. Feasibility was demonstrated with 97% completing MELCARE. Utility was demonstrated on a customised survey and supported by a reduction in the mean DT score (initial: 5.6, SD: 2.9; follow-up: 1.5, SD: 1.2). Acceptability was demonstrated on 3/4 AIM items.

CONCLUSION

MELCARE was feasible and acceptable with high levels of utility. However, the consent rate was 57% indicating some people do not require support. Future studies should consider MELCARE's optimal timing, resourcing, and cost-effectiveness.

Prognostic value of 2-[18F]FDG PET-CT in metastatic melanoma patients receiving immunotherapy

PURPOSE

The 2-fluorodeoxyglucose positron emission tomography/computed tomography (2-[¹⁸F]FDG PET/CT) is used for the evaluation of response to immunotherapy in malignant melanoma. Here, we evaluated the prognostic value of various metabolic parameters in baseline and different time points after therapy.

METHODS

In this retrospective study, 51 metastatic melanoma patients, who had received immunotherapy, were included. Patients with baseline and two follow-up 2-[¹⁸F]FDG PET/CT studies (3 and 6 months after therapy) were selected. Multiple metabolic parameters and tumor-to-background ratios (TBRs) were extracted and correlated with OS.

RESULTS

The 3- and 5-year OS rates were 49% and 43.1%, respectively. On baseline 2-[¹⁸F]FDG PET/CT, only standardized uptake value corrected for lean body mass (SUL_max and SUL_peak), as well as most of the TBRs were predictive for 3- and 5-year OS rates. Metabolic tumor volume (MTV), total lesion glycolysis (TLG), and most of the TBRs were predictive on both follow-up studies. Also, the changes in values of MTV, TLG and most of the TBRs from the baseline to the 3-month and 6- month follow-up studies were prognostic. On multivariate analysis, all of the most predictive parameters for OS were derived from the 3-month follow-up study. The ratio of TBR_mean to the mediastinum was the best factor (cutoff value of 2.15, sensitivity of 88.5% and specificity of 68.0% for 3-year survival).

CONCLUSION

Metabolic parameters derived from 2-[¹⁸F]FDG PET/CT are valuable tools for the prediction of 3- and 5-year OS rates in metastatic melanoma patients undergoing immunotherapy. The 3-month follow-up 2-[¹⁸F]FDG PET/CT is of particular importance in this regard.

Discontinuation of immune checkpoint inhibitor (ICI) above 18 months of treatment in real-life patients with advanced non-small cell lung cancer (NSCLC): INTEPI, a multicentric retrospective study

BACKGROUND

The optimal treatment duration of ICIs for patients with advanced NSCLC remains uncertain. In phase 3 clinical trials, treatment continued for 2 years or until disease progression with similar long-term survival rates. Real-life data are missing.

PATIENTS AND METHODS

This academic multicentric retrospective study aims at analyzing the characteristics of patients who discontinued treatment after at least 18 months of ICI monotherapy, in the setting of controlled disease.

RESULTS

Of the 1127 patients treated with immunotherapy in the given period in six centers, 107 patients had their tumor controlled after at least 18 months of treatment and 54 (50%) of them had discontinued ICI. The median duration of treatment was 26 months. Treatment was stopped due to prescriber choice or toxicity in 46% and 22% of cases, respectively. After a median follow-up of 21 months from ICI discontinuation (95% CI 15.0-26.1 months), 18 (33%) patients experienced tumor progression after a median time of 10.0 months (range 2-33). From discontinuation, 12-month overall survival (OS) and progression-free survival (PFS) were 90% (95% CI 77.7-95.7) and 71% (95% CI 56.8-81.5), respectively; 24-month OS and PFS were 84% (95% CI 68.7-92.2) and 63% (95% CI 46.1-76.2), respectively. Duration of disease control after ICI discontinuation was correlated with tumor response at treatment discontinuation: PFS rate at 12 months was 76% after complete response (CR n = 11) or partial response (PR n = 37) and 22% after only stable disease (SD n = 6) as best response, p-value = 0.0002. PFS rate at 12 months was 80% for CR and/or complete metabolic response with 18F-FDG PET/CT (CMR) and 65% for others. Fourteen patients out of the 18 relapse patients received a subsequent treatment: seven with ICI rechallenge (best response 14% PR and 86% SD) and five with localized therapy with 60% CR.

CONCLUSIONS

This real-life study provides new insight into long-term outcomes of patients with advanced NSCLC treated with ICI for at least 18 months before treatment discontinuation in the absence of PD. Tumor response and CMR with FDG PET just before therapy discontinuation may be a predictive factor of prolonged disease control upon discontinuation. These results call for caution in discontinuing treatment in patients with stable disease as the best response.

Immunotherapy Monitoring with Immune Checkpoint Inhibitors Based on [18F]FDG PET/CT in Metastatic Melanomas and Lung Cancer

Immunotherapy with checkpoint inhibitors has prompted a major change not only in cancer treatment but also in medical imaging. In parallel with the implementation of new drugs modulating the immune system, new response criteria have been developed, aiming to overcome clinical drawbacks related to the new, unusual, patterns of response characterizing both solid tumors and lymphoma during the course of immunotherapy. The acknowledgement of pseudo-progression, hyper-progression, immune-dissociated response and so forth, has become mandatory for all imagers dealing with this clinical scenario. A long list of acronyms, i.e., irRC, iRECIST, irRECIST, imRECIST, PECRIT, PERCIMT, imPERCIST, iPERCIST, depicts the enormous effort made by radiology and nuclear medicine physicians in the last decade to optimize imaging parameters for better prediction of clinical benefit in immunotherapy regimens. Quite frequently, a combination of clinical-laboratory data with imaging findings has been tested, proving the ability to stratify patients into various risk groups. The next steps necessarily require a large scale validation of the most robust criteria, as well as the clinical implementation of immune-targeting tracers for immuno-PET or the exploitation of radiomics and artificial intelligence as complementary tools during the course of immunotherapy administration. For the present review article, a summary of PET/CT role for immunotherapy monitoring will be provided. By scrolling into various cancer types and applied response criteria, the reader will obtain necessary information for better understanding the potentials and limitations of the modality in the clinical setting.

DMSA-SPECT: A Novel Approach to Nephron Sparing SBRT for Renal Cell Carcinoma

PURPOSE

Stereotactic body radiation therapy (SBRT) treatment planning for renal cell carcinoma requires accurate delineation of tumor from normal tissue due to the radiosensitivity of normal renal cortical tissue. Tc-99m dimercapto succinic acid (DMSA) renal imaging is a functional imaging technique that precisely differentiates normal renal cortical tissue from tumor. There are no prior publications reporting using this imaging modality for SBRT treatment planning.

METHODS AND MATERIALS

A 59-year-old female with stage IV renal cell carcinoma progressed on systemic therapy and was dispositioned to primary cytoreduction with SBRT. She had baseline renal dysfunction and her tumor was 9 cm without clear delineation from normal tissue on conventional imaging. DMSA-single-photon emission computerized tomography (SPECT)/computed tomography (CT) was used for treatment planning.

RESULTS

DMSA-SPECT/CT precisely delineated normal renal cortical tissue from tumor. Three months after treatment, labs were stable and DMSA-SPECT/CT was unchanged. The treated lesion had markedly decreased positron emission tomography avidity.

CONCLUSIONS

DMSA-SPECT or SPECT/CT can be incorporated into radiation therapy planning for renal lesions to improve target delineation and better preserve renal function.

FDG-PET to predict long-term outcome from anti-PD-1 therapy in metastatic melanoma

BACKGROUND

We have previously shown that 75% of patients treated with programmed cell death protein 1 (PD-1) with or without CTLA4 who have not progressed by 1 year have complete metabolic response (CMR), including two-thirds of patients with partial response (PR). We now report 5-year outcomes.

PATIENTS AND METHODS

Retrospective analysis of 104 patients with baseline and 1-year positron emission tomography (PET) and computed tomography (CT). The 1-year response was determined using RECIST for CT and European Organisation for Research and Treatment of Cancer (EORTC) criteria for PET. Progression-free survival (PFS) and overall survival (OS) were determined from the 1-year landmark.

RESULTS

At the median follow-up of 61 months (range 58-64 months) from 1-year PET, 94% remained alive and all but one had discontinued treatment after a median treatment duration of 23 months (range 1-59 months). Disease progression occurred in 19 patients (18%): 10 (53%) while on treatment and 12 (63%) in solitary sites for which 8 (67%) received local treatment. RECIST PFS rate at 5 years after PET was higher in complete response (CR) compared with PR/stable disease (SD) (93% versus 76%, respectively) and CMR compared with non-CMR (90% versus 54%, respectively). In patients with PR, 5-year PFS rate was superior in CMR (88% and 59%). A total of 35 (34%) patients (14/29 in CR, 31/78 in CMR) discontinued treatment within 12 months, largely due to toxicity, with no impact on PFS rate compared with those that continued (84% versus 78%). Despite progression events, OS rate at 5 years was excellent and similar in patients with CR and PR/SD (100% versus 91%, respectively) as well as in those with CMR and non-CMR (96% versus 87%, respectively).

CONCLUSIONS

Five years after the 1-year PET, sustained responses are observed in the majority of patients, particularly in those with CMR. PET continues to predict progression better than CT, particularly in those with residual disease on CT. In the minority that progress, often in solitary sites and managed locally, OS rate remains excellent. PET is effective in evaluating residual lesions on CT and can predict long-term benefit.

Fractal and Multifractal Analysis of PET-CT Images for Therapy Assessment of Metastatic Melanoma Patients under PD-1 Inhibitors: A Feasibility Study

Longitudinal whole-body PET-CT scans with F-18-fluorodeoxyglucose (¹⁸F-FDG) in patients suffering from metastatic melanoma were analyzed and the tracer distribution in patients was compared with that of healthy controls. Nineteen patients with metastatic melanoma were scanned before, after two and after four cycles of treatment with PD-1 inhibitors (pembrolizumab, nivolumab) applied as monotherapy or as combination treatment with ipilimumab. For comparison eight healthy controls were analyzed. As quantitative measures for the comparison between controls and patients, the nonlinear fractal dimension (FD) and multifractal spectrum (MFS) were calculated from the digitized PET-CT scans. The FD and MFS measures, which capture the dispersion of the tracer in the body, decreased with disease progression, since the tracer particles tended to accumulate around metastatic sites in patients, while the measures increased when the patients' clinical condition ameliorate. The MFS measure gave better predictions and were consistent with the PET Response Evaluation Criteria for Immunotherapy (PERCIMT) in 81% of the cases, while FD agreed in 77% of all cases. These results agree, qualitatively, with a previous study of our group when treatment with ipilimumab monotherapy was considered.

FDG-PET/CT imaging for evaluating durable responses to immune check point inhibitors in patients with advanced cutaneous squamous cell carcinoma

Background

The role of FDG-PET/CT imaging in assessing response to immunotherapy in advanced cutaneous squamous cell carcinoma (CSCC) is unknown. This study compared complete metabolic response (CMR) rates by FDG-PET and RECIST1.1 via CT or MRI in patients on cemiplimab for > 10 months.

Methods

This was a single-centre retrospective study of 15 patients treated with cemiplimab for advanced CSCC who had CT/MRI and FDG-PET/CT at > 10 months to assess metabolic treatment response. The median age was 73 years (range 55–84) and 93% were male. RECIST1.1 and PERCIST1.0 tumor responses were evaluated by blinded readers.

Results

Seventy-three percent (11/15) (95%CI 44.9, 92.2%) achieved a CMR on PET. Of these 11, on RECIST1.1 there was one complete response, 9 partial responses and one stable disease.

Conclusions

In patients on cemiplimab for > 10 months, there was discordance between CR rates on FDG-PET versus RECIST1.1. FDG-PET/CT may have utility for clarifying depth of response in patients treated with immunotherapy for CSCC.

PET/CT scan and biopsy-driven approach for safe anti-PD-1 therapy discontinuation in patients with advanced melanoma

Background

Limited data exist on safe discontinuation of antiprogrammed cell death protein 1 (PD-1) therapy in responding patients with advanced melanoma. The use of 18fluorodeoxyglucose (¹⁸FDG)-PET/CT scan and tumor biopsy for assessment of active disease may be an effective predictive biomarker to guide such treatment decisions.

Methods

A retrospective study of 122 patients with advanced melanoma treated with anti-PD-1 monotherapy or anti-PD-1/anticytotoxic T-lymphocyte-associated protein 4 combination therapy at Georgetown Lombardi Comprehensive Cancer Center was conducted. Uveal melanoma patients and those receiving concurrent experimental therapy were excluded. Baseline characteristics, treatment outcomes, and survival were analyzed. Patients who decided to come off treatment typically after 12 months using CT scan radiographic complete response (CR), ¹⁸FDG-PET/CT scan complete metabolic response (CMR) or tumor biopsy of a non-CR/CMR tumor site negative for active disease (possible pathological CR) were identified and compared with patients who discontinued treatment due to toxicity while their disease was in control. Event-free survival (EFS) was assessed from the last dose of anti-PD-1 therapy to progression requiring subsequent treatment (surgery, radiation, and/or systemic therapy) or referral to hospice/death due to melanoma.

Results

24 (20%) patients discontinued treatment by choice with no active disease and 28 (23%) patients discontinued treatment due to toxicity with disease control after 12-month and 4-month median treatment durations, respectively. Similar baseline characteristics were observed between cohorts except higher prior receipt of ipilimumab (29% vs 7%; p=0.036) and fewer BRAF mutant positive disease (17% vs 41%; p=0.064) in patients off treatment by choice. Three-year EFS rates were 95% and 71%, respectively. No significant associations between EFS and sex, disease stage, lactate dehydrogenase elevation, BRAF status, prior systemic therapy, ECOG performance status, presence of brain metastases, or combination versus monotherapy were observed. Tumor biopsies led to alternative management in 3/10 patients due to active metastatic melanoma or second malignancy.

Conclusions

Anti-PD-1 therapy discontinuation after 12 months when no active disease is observed on CT scan, PET/CT scan or tumor biopsy may have low rates of disease relapse in patients with advanced melanoma. Biopsy of residual disease may frequently lead to a change in management. These findings are undergoing validation in the EA6192 trial.

Long-term outcomes in patients with advanced melanoma who had initial stable disease with pembrolizumab in KEYNOTE-001 and KEYNOTE-006

Objective:

Patients with melanoma and early stable disease (SD) with pembrolizumab have unclear prognosis. We present post hoc analyses of long-term outcomes for patients with early SD, partial response (PR) or complete response (CR) with pembrolizumab.

Patients and methods:

Patients who received pembrolizumab in the KEYNOTE-001 and KEYNOTE-006 studies and had SD, PR or CR at weeks 12 or 24 were included.

Results:

Of 294 patients in the week 12 analysis, 107 (36.4%) had SD at week 12, of whom 7 (6.5%) had a best overall response of CR, 43 (40.2%) had PR and 57 (53.3%) had SD. Forty-eighte–month overall survival (OS) rates were 95.2%, 73.0% and 47.7%, respectively, for patients with CR, PR and SD at week 12. Similar results were observed in the 241 patients in the week 24 analysis. Forty-eight–month OS rates were 72.1% for patients with SD at week 12 followed by subsequent response and 75.0% for patients with PR at week 12 followed by no change in response or progression. Thirty-six–month and 48-month OS rates were 11.6% and not reached, respectively, for patients with SD at week 12 followed by progression before week 24.

Conclusions:

A substantial proportion of patients (46.7%) with early (week 12) SD with pembrolizumab achieved subsequent PR or CR. Patients with SD at week 12 and subsequent CR/PR had similar survival to those who maintained PR. In contrast, patients with SD at week 12 and subsequent progression had poor survival outcomes. These findings may guide treatment decisions for patients achieving early SD.

Trial registration:

Clinicaltrials.gov: NCT01295827 (KEYNOTE-001); NCT01866319 (KEYNOTE-006).

Immune checkpoint inhibitors in melanoma

Immune checkpoint inhibitors target the dysfunctional immune system, to induce cancer-cell killing by CD8-positive T cells. Immune checkpoint inhibitors, specifically anti-CTLA4 and anti-PD-1 antibodies, have revolutionised the management of many cancers, particularly advanced melanoma, for which tumour regression and long-term durable cancer control is possible in nearly 50% of patients, compared with less than 10% historically. Despite the absence of adequately powered trial data, combined anti-CTLA4 and anti-PD-1 checkpoint inhibition has the highest 5-year overall survival rate of all therapies in advanced melanoma, and has high activity in melanoma brain metastases. A phase 3 study has shown the addition of an anti-LAG3 antibody to nivolumab improves progression-free survival, but its effect on overall survival and how this combination compares to combined anti-CTLA4 and anti-PD-1 checkpoint inhibition is unknown. At present, there are no highly sensitive and specific biomarkers of response to immune checkpoint inhibitors, and clinical factors, such as volume and sites of disease, serum lactate dehydrogenase, and BRAF mutation status, are used to select initial therapy for patients with advanced melanoma. Immune checkpoint inhibitors can induce autoimmune toxicities by virtue of their mechanism of action. These toxicities, termed immune-related adverse events, occur most frequently with combined anti-CTLA4 and anti-PD-1 checkpoint inhibition; can have a variety of presentations; can affect any organ system (most often the skin, colon, endocrine system, and liver); and appear to mimic classic autoimmune diseases. Immune-related adverse events require prompt recognition and management, which may be different from the autoimmune disease it mimics. Immune checkpoint inhibitors appear to be safe for use in patients with HIV, viral hepatitis, and patients with mild-to-moderate pre-existing autoimmune diseases. Patients with organ transplants can respond to immune checkpoint inhibitors but have a high chance of transplant loss. PD-1 inhibitors are now an established standard of care as adjuvant therapy in high-risk resected stage III or IV melanoma. Neoadjuvant checkpoint inhibition for resectable stage III melanoma, which is currently limited to clinical trials, is emerging as a highly effective therapy.

Multiparametric MRI of early tumor response to immune checkpoint blockade in metastatic melanoma

BACKGROUND

Immune checkpoint inhibitors are now standard of care treatment for many cancers. Treatment failure in metastatic melanoma is often due to tumor heterogeneity, which is not easily captured by conventional CT or tumor biopsy. The aim of this prospective study was to investigate early microstructural and functional changes within melanoma metastases following immune checkpoint blockade using multiparametric MRI.

METHODS

Fifteen treatment-naïve metastatic melanoma patients (total 27 measurable target lesions) were imaged at baseline and following 3 and 12 weeks of treatment on immune checkpoint inhibitors using: T2-weighted imaging, diffusion kurtosis imaging, and dynamic contrast-enhanced MRI. Treatment timepoint changes in tumor cellularity, vascularity, and heterogeneity within individual metastases were evaluated and correlated to the clinical outcome in each patient based on Response Evaluation Criteria in Solid Tumors V.1.1 at 1 year.

RESULTS

Differential tumor growth kinetics in response to immune checkpoint blockade were measured in individual metastases within the same patient, demonstrating significant intertumoral heterogeneity in some patients. Early detection of tumor cell death or cell loss measured by a significant increase in the apparent diffusivity (Dapp) (p<0.05) was observed in both responding and pseudoprogressive lesions after 3 weeks of treatment. Tumor heterogeneity, as measured by apparent diffusional kurtosis (Kapp), was consistently higher in the pseudoprogressive and true progressive lesions, compared with the responding lesions throughout the first 12 weeks of treatment. These preceded tumor regression and significant tumor vascularity changes (Ktrans, ve, and vp) detected after 12 weeks of immunotherapy (p<0.05).

CONCLUSIONS

Multiparametric MRI demonstrated potential for early detection of successful response to immune checkpoint inhibitors in metastatic melanoma.

Primary Malignant Melanoma of the Oropharynx Presented on 18F-FDG PET/CT

ABSTRACT

Primary malignant melanoma in the oropharynx is extremely rare. A 49-year-old man presented with a 3-month history of progressive dysphagia. An outside CT scan of the head and neck showed a space-occupying lesion in the oropharynx. Staging with FDG PET/CT demonstrated a hypermetabolic mass in the right wall of the oropharynx. A biopsy revealed malignant melanoma. The patient underwent total resection of the tumor, with no recurrence after 6-month follow-up.

Precision Nuclear Medicine: The Evolving Role of PET in Melanoma

The clinical management of melanoma patients has been rapidly evolving with the introduction of new targeted immuno-oncology (IO) therapeutics. The current diagnostic paradigms for melanoma patients begins with the histopathologic confirmation of melanoma, initial staging of disease burden with imaging and surgical approaches, treatment monitoring during systemic cytotoxic chemotherapy or IO therapeutics, restaging after completion of adjuvant systemic, surgical, and/or external radiation therapy, and the detection of recurrent malignancy/metastatic disease following therapy. New and evolving imaging approaches with positron-emission tomography (PET) imaging technologies, imaging methodologies, image reconstruction, and image analytics will likely continue to improve tumor detection, tumor characterization, and diagnostic confidence, enabling novel precision nuclear medicine practices for managing melanoma patients. This review will examine current concepts and challenges with existing PET imaging diagnostics for melanoma patients and introduce exciting new opportunities for PET in the current era of IO therapeutics.