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

FDG-PET associations with pathological response and survival with neoadjuvant immunotherapy for melanoma

BACKGROUND

Neoadjuvant immunotherapy has become the new standard of care for stage III melanoma. This study sought to describe the metabolic changes seen with fludeoxyglucose-18-positron emission tomography (FDG-PET) following neoadjuvant immunotherapy in patients with melanoma and explore associations with pathological response and recurrence-free survival (RFS).

METHODS

Data from patients with macroscopic stage III nodal melanoma treated with neoadjuvant checkpoint inhibitor therapy were pooled from five melanoma centers. All patients underwent baseline and preoperative FDG-PET and CT assessments, and all had surgery. Pathological response was determined using the International Neoadjuvant Melanoma Consortium criteria, radiological response using Response Evaluation Criteria in Solid Tumors (RECIST) criteria, and FDG-PET response using European Organization for Research and Treatment of Cancer (EORTC) criteria. The primary endpoint was to explore the associations of metabolic and radiological responses with pathological response; secondary endpoints were RFS outcomes stratified by each response category.

RESULTS

115 patients were included, 69% male, median age 59 years (27-92), 43% BRAF mutant, and median follow-up was 22.2 months (95% CI 13.7 to 26.4). 40 patients received anti-PD-1 monotherapy, 20 patients received pembrolizumab combined with lenvatinib, and 55 patients received ipilimumab and nivolumab. The major pathological response (MPR) rate was 62%, and the pathological complete response rate was 51%. RECIST response underestimated pathological response; patients achieving RECIST stable disease (38%) had a 50% chance of achieving MPR. The FDG-PET metabolic response rate was 73%, with most achieving an MPR (80%), especially in patients with a complete metabolic response (CMR, 96% MPR). A small proportion of patients (10%) had stable metabolic disease on FDG-PET, and all these patients were non-MPR. Patients with progressive metabolic disease were also in the majority non-MPR (79%). Patients with MPR, complete response/partial response on CT, and CMR/partial metabolic response on FDG-PET had a favorable 24-month RFS (95.6%, 97.3%, and 93.7%, respectively), with FDG-PET able to identify a greater proportion of patients with favorable progression-free survival (PFS) than pathology or CT (73%, 62%, and 43%, respectively).

CONCLUSION

Neoadjuvant immunotherapy has high FDG-PET response rates in melanoma. FDG-PET response associates with pathological response and confers impressive RFS, suggesting this could be an important clinical tool.

Real-world management of patients with complete response under immune-checkpoint inhibition for advanced melanoma

BACKGROUND

Up to now, the optimal duration of immune checkpoint inhibitors (ICI) has not been evaluated in prospective studies. However, current clinical practice requires decisions to be made regarding the duration of ICI in complete responders.

MATERIAL AND METHODS

A survey was sent to 80 DeCOG skin cancer centers to assess how decisions are made on treatment duration of ICI in melanoma after having reached complete response, and staging intervals after ICI discontinuation. All responses received by March 10, 2024 (51 centers) were included.

RESULTS

The duration of ICI after having achieved complete remission varies between centers from three to 36 months. In total, 66% of the DeCOG centers continue treatment for up to 6 months, after having achieved complete remission (CR) with ICI. In the first year after discontinuation of ICI, most centers perform staging intervals (CT/MRI) every 3 months. More than 60% of centers continue staging at least once per year even in the 4th and 5th year after discontinuation.

CONCLUSIONS

There are significant differences between the centers regarding staging intervals and duration of ICI upon CR. Prospective studies are necessary to determine the optimal time point of ICI discontinuation and follow-up.

Early-time-point 18F-FDG-PET/CT and other prognostic biomarkers of survival in metastatic melanoma patients receiving immunotherapy

BACKGROUND

A considerable proportion of metastatic melanoma (mM) patients do not respond to immune checkpoint inhibitors (ICIs). There is a great need to develop noninvasive biomarkers to detect patients, who do not respond to ICIs early during the course of treatment. The aim of this study was to evaluate the role of early [18F]2fluoro-2-deoxy-D-glucose PET/CT (18F-FDG PET/CT) at week four (W4) and other possible prognostic biomarkers of survival in mM patients receiving ICIs.

PATIENTS AND METHODS

. In this prospective noninterventional clinical study, mM patients receiving ICIs regularly underwent 18F-FDG PET/CT: at baseline, at W4 after ICI initiation, at week sixteen and every 16 weeks thereafter. The tumor response to ICIs at W4 was assessed via modified European Organisation for Research and Treatment of Cancer (EORTC) criteria. Patients with progressive metabolic disease (PMD) were classified into the no clinical benefit group (no-CB), and those with other response types were classified into the clinical benefit group (CB). The primary end point was survival analysis on the basis of the W4 18F-FDG PET/CT response. The secondary endpoints were survival analysis on the basis of LDH, the number of metastatic localizations, and immune-related adverse events (irAEs). Kaplan-Meier analysis and univariate Cox regression analysis were used to assess the impact on survival.

RESULTS

Overall, 71 patients were included. The median follow-up was 37.1 months (952% CI = 30.1-38.0). Three (4%) patients had only baseline scans due to rapid disease progression and death prior to W4 18F-FDG-PET/CT. Fifty-one (72%) patients were classified into the CB group, and 17 (24%) were classified into the no-CB group. There was a statistically significant difference in median overall survival (OS) between the CB group (median OS not reached [NR]; 95% CI = 17.8 months - NR) and the no-CB group (median OS 6.2 months; 95% CI = 4.6 months - NR; p = 0.003). Univariate Cox analysis showed HR of 0.4 (95% CI = 0.18 - 0.72; p = 0.004). median OS was also significantly longer in the group with normal serum LDH levels and the group with irAEs and cutaneous irAEs.

CONCLUSIONS

Evaluation of mM patients with early 18F-FDG-PET/CT at W4, who were treated with ICIs, could serve as prognostic imaging biomarkers. Other recognized prognostic biomarkers were the serum LDH level and occurrence of cutaneous irAEs.

Discontinuation of immune checkpoint inhibitors for reasons other than disease progression and the impact on relapse and survival of advanced melanoma patients. A systematic review and meta-analysis

Background

Despite durable responses achieved with Immune Checkpoint Inhibitors (ICIs), data about optimal duration of treatment, especially in the context of adverse events, remain scarce.

Objective

To systematically review the evidence concerning the impact of treatment discontinuation with ICIs for reasons other than progressive disease (PD) on relapse rates and survival of melanoma patients.

Methods

A systematic literature search was conducted in three electronic databases until July 2024. Studies referring to melanoma patients who ceased ICIs electively (i.e. due to complete response (CR), protocol completion or patient/physician's wish) or due to treatment-limiting toxicities (TLTs) were selected. Relapse rates (RRs) post cessation, time to PD, rechallenge and disease control rate (DCR) after 2nd course were the main outcomes. Random-effects models were preferred, and subgroup and sensitivity analyses were conducted to investigate possible sources of heterogeneity.

Results

38 and 35 studies were included in qualitative and quantitative synthesis, respectively. From 2542 patients discontinued treatment with ICIs electively or due to TLTs, 495 experienced progression [number of studies (n)=34, RR 20.9%, 95%CI 17.1 - 24.7%, I2 85%) and higher rates were detected in patients with TLTs compared to elective discontinuation. Mean time to PD was 14.26 months (n=18, mean time 14.26, 95%CI 11.54 - 16.98, I2 93%) and was numerically higher in patients who ceased for CR compared to patients with TLTs. Treatment duration before cessation was not associated with risk and time to relapse, while mucosal melanomas and non-CR as BOR during treatment led to increased risk for relapse and shorter time to PD compared to other histologic subtypes or CR. Rechallenge with ICI resulted in 57.3% DCR and 28.6% pooled CR rates (n=22, CR rate 28.6%, 95%CI 17.1 - 40.2, I2 68%). Heterogeneity among studies was high, but subgroup analysis based on type of ICI used (anti-CTL4 and anti-PD1 inhibitor or anti-PD1 monotherapy) and type of study (RCTs or observational studies), along with sensitivity analyses did not reveal significant alterations in results.

Conclusion

Discontinuation of ICIs in patients without progression is possible. Outcomes to rechallenge with ICIs may differ depending on the reason for discontinuation, but remains a considerable option.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier CRD42024547792.

Multimodal Imaging Approach for Tumor Treatment Response Evaluation in the Era of Immunotherapy

ABSTRACT

Immunotherapy is likely the most remarkable advancement in lung cancer treatment during the past decade. Although immunotherapy provides substantial benefits, their therapeutic responses differ from those of conventional chemotherapy and targeted therapy, and some patients present unique immunotherapy response patterns that cannot be judged under the current measurement standards. Therefore, the response monitoring of immunotherapy can be challenging, such as the differentiation between real response and pseudo-response. This review outlines the various tumor response patterns to immunotherapy and discusses methods for quantifying computed tomography (CT) and 18 F-fluorodeoxyglucose positron emission tomography (PET) in the field of lung cancer. Emerging technologies in magnetic resonance imaging (MRI) and non-FDG PET tracers are also explored. With immunotherapy responses, the role for imaging is essential in both anatomical radiological responses (CT/MRI) and molecular changes (PET imaging). Multiple aspects must be considered when assessing treatment responses using CT and PET. Finally, we introduce multimodal approaches that integrate imaging and nonimaging data, and we discuss future directions for the assessment and prediction of lung cancer responses to immunotherapy.

Long-term outcomes among patients who respond within the first year to nivolumab plus ipilimumab or nivolumab monotherapy: A pooled analysis in 935 patients

PURPOSE

To investigate the predictive value of RECIST response within 3, 6, or 12 months on long-term survival, and explore differences between nivolumab+ipilimumab and nivolumab monotherapy, we analyzed pooled 5-year data of 935 responder and non-responder patients at various time points after treatment initiation in CheckMate 069, 066, and 067 studies.

PATIENTS AND METHODS

Treatment-naive advanced melanoma patients received nivolumab+ipilimumab or nivolumab monotherapy. To decrease immortal time bias, 3-, 6-, or 12-month overall survival (OS) and progression-free survival (PFS) landmark analyses were performed. Association between characteristics and response was evaluated by univariate and multivariate analyses.

RESULTS

Response rates at any time were 58 % (239/409) for nivolumab+ipilimumab and 44 % (230/526) for nivolumab monotherapy. In 12-month landmark analyses, 5-year OS rates for responders versus non-responders were 82 % versus 40 % with nivolumab+ipilimumab (HR=0.23 [95 % CI, 0.15-0.35]) and 76 % versus 32 % with nivolumab monotherapy (HR=0.22 [95 % CI, 0.16-0.31]). PFS rates were 83 % versus 32 % and 69 % versus 46 %, respectively. Similar strong associations between response at 3 and 6 months and 5-year OS and PFS were also observed with more than 70 % of the responses observed in the first 3 months. Response rates correlated with baseline LDH and PD-L1 status by multivariate analysis but the association between response and long-term survival was maintained in landmark analyses even among patients with high LDH and low PD-L1 expression.

CONCLUSION

Clinical response evaluated in the first months of therapy is a strong predictor of long-term survival, even in patients with poor prognostic biomarkers.

Immunotherapy response and resistance in patients with advanced uveal melanoma: a retrospective cohort study

Metastatic uveal melanoma (mUM) is associated with poor prognosis. Ipilimumab/nivolumab has shown antitumor efficacy in phase II studies. Tebentafusp resulted in longer overall survival (OS) compared to investigator`s choice in a phase III study. We sought to describe the radiological response patterns of mUM patients treated with immunotherapy. Patients with mUM treated with ipilimumab/nivolumab and tebentafusp between July 2018 and December 2022, with available radiological assessment per RECISTv1.1 and/or imPERCIST5, were retrospectively identified and included. Progression-free survival (PFS) and OS rates, liver-specific response and pathological assessment in available liver biopsies were evaluated. In the ipilimumab/nivolumab group, median PFS (mPFS) was 2.9 months (95% CI 2.2-28.6) and mOS 28.9 months (95% CI 12.7-NR). Complete (CMR) and partial (PMR) metabolic response per imPERCIST5, and partial response (PR) per RECISTv1.1 were associated with longer PFS and OS by trend, compared to morphologically and metabolically stable or progressive disease. In the tebentafusp group, mPFS was 2.7 months (95% CI 2.2-3) and mOS 18.6 months (95% CI 11.5-NR). PMR and PR were associated with longer PFS by trend. In both treatments, the overall treatment response was associated with the radiological response at the liver site. In available liver tumor biopsies, differences in pathological and radiological responses were noted. ImPERCIST5 and RECIST v1.1 are valuable tools in the radiological response assessment, but both methods display limitations. Accurate biomarkers to stratify patients at risk for disease progression and future translational studies to investigate mechanisms of response and resistance are required.

The impact of introducing deep learning based [18F]FDG PET denoising on EORTC and PERCIST therapeutic response assessments in digital PET/CT

BACKGROUND

[18F]FDG PET denoising by SubtlePET™ using deep learning artificial intelligence (AI) was previously found to induce slight modifications in lesion and reference organs' quantification and in lesion detection. As a next step, we aimed to evaluate its clinical impact on [18F]FDG PET solid tumour treatment response assessments, while comparing "standard PET" to "AI denoised half-duration PET" ("AI PET") during follow-up.

RESULTS

110 patients referred for baseline and follow-up standard digital [18F]FDG PET/CT were prospectively included. "Standard" EORTC and, if applicable, PERCIST response classifications by 2 readers between baseline standard PET1 and follow-up standard PET2 as a "gold standard" were compared to "mixed" classifications between standard PET1 and AI PET2 (group 1; n = 64), or between AI PET1 and standard PET2 (group 2; n = 46). Separate classifications were established using either standardized uptake values from ultra-high definition PET with or without AI denoising (simplified to "UHD") or EANM research limited v2 (EARL2)-compliant values (by Gaussian filtering in standard PET and using the same filter in AI PET). Overall, pooling both study groups, in 11/110 (10%) patients at least one EORTCUHD or EARL2 or PERCISTUHD or EARL2 mixed vs. standard classification was discordant, with 369/397 (93%) concordant classifications, unweighted Cohen's kappa = 0.86 (95% CI: 0.78-0.94). These modified mixed vs. standard classifications could have impacted management in 2% of patients.

CONCLUSIONS

Although comparing similar PET images is preferable for therapy response assessment, the comparison between a standard [18F]FDG PET and an AI denoised half-duration PET is feasible and seems clinically satisfactory.

Outcomes of patients with advanced solid tumors who discontinued immune-checkpoint inhibitors: a systematic review and meta-analysis

Background

The outcome of patients with metastatic tumors who discontinued immune checkpoint inhibitors (ICIs) not for progressive disease (PD) has been poorly explored. We performed a meta-analysis of all studies reporting the clinical outcome of patients who discontinued ICIs for reasons other than PD.

Methods

We searched PubMed, Embase and Scopus databases, from the inception of each database to December 2023, for clinical trials (randomized or not) and observational studies assessing PD-(L)1 and CTLA-4 inhibitors in patients with metastatic solid tumors who discontinued treatment for reasons other than PD. Each study had to provide swimmer plots or Kaplan-Meier survival curves enabling the reconstruction of individual patient-level data on progression-free survival (PFS) following the discontinuation of immunotherapy. The primary endpoint was PFS from the date of treatment discontinuation overall and according to tumor histotype, type of treatment and reason of discontinuation. The Combersure's method was used to estimate meta-analytical non-parametric summary survival curves assuming random effects at study level.

Findings

Thirty-six studies (2180 patients) were included. The pooled median PFS (mPFS) was 24.7 months (95% CI, 18.8-30.6) and the PFS-rate at 12, 24, and 36 months was respectively 69.8% (95% CI, 63.1-77.3), 51.0% (95% CI, 43.4-59.8) and 34.0% (95% CI, 27.0-42.9). Univariable analysis showed that the mPFS was significantly longer for patients with melanoma (43.0 months), as compared with non-small cell lung cancer (NSCLC, 13.5 months) and renal cell carcinoma (RCC, 10.0 months; between-strata comparison test p-value < 0.001); for patients treated with anti-PD-(L)1 + anti-CTLA-4 as compared with anti-PD-(L)1 monotherapy (44.6 versus 19.9 months; p-value < 0.001), and in NSCLC when the reason of treatment discontinuation was elective as compared with toxicity onset (19.6 versus 4.8 months; p-value = 0.003). The multivariable analysis confirmed these differences.

Interpretation

The long-term outcome of patients who stopped ICIs for reasons other than PD was substantially affected by clinicopathological features: PFS after treatment discontinuation was longer in patients with melanoma, and/or treated with anti-PD-(L)1 + anti-CTLA-4, and shorter in patients with RCC or in those patients with NSCLC who stopped treatment for toxicity onset.

Funding

The Italian Ministry of University and Research (PRIN 2022Y7HHNW).

Patterns of radiological response to tebentafusp in patients with metastatic uveal melanoma

Metastatic uveal melanoma (mUM) is a rare type of melanoma with poor outcomes. The first systemic treatment to significantly prolong overall survival (OS) in patients with mUM was tebentafusp, a bispecific protein that can redirect T-cells to gp-100 positive cells. However, the objective response rate according to Response Evaluation Criteria in Solid Tumors (RECIST) may underestimate the clinical impact of tebentafusp. As metabolic response assessed by PET Response Criteria in Solid Tumors (PERCIST) has been reported to better correlate with clinical outcome, we here compared the patterns of radiological and morphological responses in HLA-A*02:01-positive patients with mUM treated with tebentafusp. In the 19 enrolled patients, RECIST showed an overall response rate (ORR) of 10%, median progression-free survival of 2.8 months (95% CI 2.5-8.4), and median OS (mOS) of 18.8 months. In 10 patients, where both RECIST and PERCIST evaluation was available, the ORR was 10% for both; however, the PFS was longer for PERCIST compared to RECIST, 3.1 and 2.4 months, respectively. A poor agreement between the criteria was observed at all assessments (Cohen's kappa ≤0), yet they differed significantly only at the first on-treatment imaging ( P  = 0.037). Elevated baseline LDH and age were associated with an increased risk for RECIST progression, while lymphocyte decrease after the first infusions correlated to reduced risk of RECIST progression. Detectable ctDNA at baseline did not correlate with progression. Early response to tebentafusp may be incompletely captured by conventional imaging, leading to a need to consider both tumor morphology and metabolism.

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.

Sinonasal mucosal melanoma treatment response assessment to immune checkpoint inhibitors using hybrid positron emission tomography imaging

The purpose of this retrospective study was to investigate response of sinonasal mucosal melanoma (SMM) patients to treatment with immune checkpoint inhibitors (ICI), using hybrid PET imaging. Fifteen SMM patients underwent hybrid PET imaging before and three months after initiation of ICI. The disease-specific survival (DSS) was calculated. Quantitative PET parameters of the primary tumor and their association with DSS and therapy response were investigated. Nine of the fifteen (60%) patients responded to ICI therapy. Patients with therapy response depicted on hybrid PET imaging had better DSS than those without (p = 0.0058). Quantitative PET parameters of the initial PET harbored no association with DSS or therapy response. However, these findings lack of sufficient statistical power and must be interpreted with caution. The first restaging PET-imaging after ICI initiation can help stratify patients with regard to DSS.

Features and Long-Term Outcomes of Stage IV Melanoma Patients Achieving Complete Response Under Anti-PD-1-Based Immunotherapy

BACKGROUND

Immune checkpoint inhibition (ICI) has changed the melanoma treatment spectrum. Few studies have examined the characteristics and long-term outcomes of patients achieving complete response (CR) under ICI.

MATERIALS AND METHODS

We evaluated patients with unresectable stage IV melanoma treated with first-line ICI. The characteristics of those achieving CR were compared with those not achieving CR. Progression-free survival (PFS) and overall survival (OS) were assessed. Late-onset toxicities, response to second-line treatment, the prognostic value of clinicopathologic features, and blood markers were examined.

RESULTS

A total of 265 patients were included; 41 (15.5%) achieved CR, while 224 (84.5%) had progressive disease, stable disease, or partial response. At the therapy start, those who had CR were more likely to be older than 65 years of age (p = 0.013), have a platelet-to-lymphocyte ratio below 213 (p = 0.036), and have lower lactate dehydrogenase levels (p = 0.008) than those not achieving a CR. For those who discontinued therapy after CR, the median follow-up time after CR was 56 months (interquartile range [IQR] 52-58) and the median time from CR to therapy end was 10 months (IQR 1-17). Five-year PFS after CR was 79% and 5-year OS was 83%. Most complete responders had a normalization of S100 at the time of CR (p < 0.001). In simple Cox regression analysis, age below 77 years at CR (p = 0.04) was associated with better prognosis after CR. Eight patients received second-line ICI; disease control was seen in 63%. Late immune-related toxicities occurred in 25% of patients, most being cutaneous immune-related toxicities.

CONCLUSIONS

Response, according to the Response Evaluation Criteria in Solid Tumors (RECIST) criteria, is, until now, the most important prognostic factor, and CR is a valid surrogate marker for long-term survival in patients treated with ICI. Our results highlight the importance of investigating the optimal therapy duration in complete responders.

[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.

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.

BRAF inhibitor cessation prior to disease progression in metastatic melanoma: Long-term outcomes

BACKGROUND

BRAF mutant melanoma treated with BRAF ± MEK inhibitor (targeted therapy) has a high response rate; however, most patients progress (PD). Some patients have durable response, but it is unknown whether treatment can be discontinued in these patients. We describe the recurrence risk, progression patterns, response to subsequent treatment, and survival of patients with advanced melanoma who ceased targeted therapy prior to PD.

PATIENTS AND METHODS

Ninety-four patients who ceased targeted therapy without progression were identified retrospectively from 11 centres: 45 were male; 81 V600E; 88 stage IV. Fifty-nine were treated with BRAF + MEK inhibitor, and 35 were treated with BRAF inhibitor alone. Median treatment duration was 29.6 months (range 0.36-77.9). At cessation, 67 were in complete response, 21 in partial response, and 2 stable disease.

RESULTS

After median follow-up from cessation of 42.9 months (range 0.0-88.7), 36 (38%) progressed; median time to progression was 4.7 months (range 0.7-56.9); 30 (83%) were asymptomatic and 7 (19%) had new brain metastases. Progression rates did not differ by best response: 34% for complete response and 43% for partial response (P = 0.65). Treatment duration was strongly associated with risk of progression: Median treatment duration was 18.3 (range 0.85-65.7) months for those who progressed and 34.6 (range 0.36-77.9) months for those who did not (P = 0.0004). Twenty-two received further targeted therapy with 15 (68%) responses.

CONCLUSION

Risk of progression after cessation of targeted therapy is strongly associated with treatment duration. Response to retreatment with targeted therapy is high.

PET/CT molecular imaging in the era of immune-checkpoint inhibitors therapy

Cancer immunotherapy, especially immune-checkpoint inhibitors (ICIs), has paved a new way for the treatment of many types of malignancies, particularly advanced-stage cancers. Accumulating evidence suggests that as a molecular imaging modality, positron emission tomography/computed tomography (PET/CT) can play a vital role in the management of ICIs therapy by using different molecular probes and metabolic parameters. In this review, we will provide a comprehensive overview of the clinical data to support the importance of 18F-fluorodeoxyglucose PET/CT (18F-FDG PET/CT) imaging in the treatment of ICIs, including the evaluation of the tumor microenvironment, discovery of immune-related adverse events, evaluation of therapeutic efficacy, and prediction of therapeutic prognosis. We also discuss perspectives on the development direction of 18F-FDG PET/CT imaging, with a particular emphasis on possible challenges in the future. In addition, we summarize the researches on novel PET molecular probes that are expected to potentially promote the precise application of ICIs.

CD69 and SBK1 as potential predictors of responses to PD-1/PD-L1 blockade cancer immunotherapy in lung cancer and melanoma

Background

PD-1/PD-L1 blockade is a promising immunotherapeutic strategy with the potential to improve the outcomes of various cancers. However, there is a critically unmet need for effective biomarkers of response to PD-1/PD-L1 blockade.

Materials and methods

Potential biomarkers of response to PD-1/PD-L1 blockade were obtained from the Cancer Treatment Response gene signature Database (CTR-DB). A comprehensive pan-cancer analysis was done on The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) datasets. Correlations between gene expression and infiltration by immune cells were assessed using TIMER, EPIC, MCPcounter, xCell, CIBERSORT, and quanTIseq. Immunophenoscore (IPS) was used to assess the potential application of the biomarkers to all TCGA tumors.

Results

Analysis of CTR-DB data identified CD69 and SBK1 as potential biomarkers of response to PD-1/PD-L1 blockade. Correlation analysis revealed that in various TCGA cancer datasets, CD69 expression level correlated positively with most immune checkpoints and tumor-infiltrating immune cells, while SBK1 expression level correlated negatively with infiltrating immune cells. IPS analysis demonstrated the ability of CD69 and SBK1 to predict PD-1/PD-L1 blockade responses in various cancers.

Conclusion

CD69 and SBK1 are potential predictors of response to cancer immunotherapy using PD-1/PD-L1 blockade. These biomarkers may guide treatment decisions, leading to precise treatment and minimizing the waste of medical resources.

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.

The Role and Potential of 18F-FDG PET/CT in Malignant Melanoma: Prognostication, Monitoring Response to Targeted and Immunotherapy, and Radiomics

Novel therapeutic approaches, consisting of immune check-point inhibitors (ICIs) and molecularly targeted therapy, have thoroughly changed the clinical management of malignant melanoma (MM), the most frequent and deadly skin cancer. Since only 30-40% of MM patients respond to ICIs, imaging biomarkers suitable for the pre-therapeutic stratification and response assessment are warmly welcome. In this scenario, positron emission computed tomography (PET/CT) with 18F-fluorodeoxyglucose (18F-FDG) has been successfully utilized for advanced MM staging and therapy response evaluation. Furthermore, several PET-derived parameters (SUVmax, MTV, TLG) were particularly impactful for the prognostic evaluation of patients submitted to targeted and immunotherapy. In this review, we performed a web-based and desktop research on the clinical applications of 18F-FDG PET/CT in MM, with a particular emphasis on the various metabolic criteria developed for interpreting PET/CT scan in patients undergoing immunotherapy or targeted therapy or a combination of both. Furthermore, the emerging role of radiomics, a quantitative approach to medical imaging applying analysis methodology derived by the field of artificial intelligence, was examined in the peculiar context, putting a particular emphasis on the potential of this discipline to support clinicians in the delicate process of building patient-tailored pathways of care.

Immune-checkpoint inhibitors: long-term implications of toxicity

The development of immune-checkpoint inhibitors (ICIs) has heralded a new era in cancer treatment, enabling the possibility of long-term survival in patients with metastatic disease, and providing new therapeutic indications in earlier-stage settings. As such, characterizing the long-term implications of receiving ICIs has grown in importance. An abundance of evidence exists describing the acute clinical toxicities of these agents, although chronic effects have not been as well catalogued. Nonetheless, emerging evidence indicates that persistent toxicities might be more common than initially suggested. While generally low-grade, these chronic sequelae can affect the endocrine, rheumatological, pulmonary, neurological and other organ systems. Fatal toxicities also comprise a diverse set of clinical manifestations and can occur in 0.4-1.2% of patients. This risk is a particularly relevant consideration in light of the possibility of long-term survival. Finally, the effects of immune-checkpoint blockade on a diverse range of immune processes, including atherosclerosis, heart failure, neuroinflammation, obesity and hypertension, have not been characterized but remain an important area of research with potential relevance to cancer survivors. In this Review, we describe the current evidence for chronic immune toxicities and the long-term implications of these effects for patients receiving ICIs.