[11C]Methionine and [11C]PBR28 as PET Imaging Tracers to Differentiate Metastatic Tumor Recurrence or Radiation Necrosis

Purpose:

As stereotactic radiosurgery (SRS) and immunotherapy are increasingly used to treat brain metastases, incidence of radiation necrosis (RN) is consequently rising. Differentiating tumor regrowth (TR) from RN is vital in management but difficult to assess using MRI. We hypothesized that tumor methionine levels would be elevated given increased metabolism and high amino acid uptake, whereas RN would increase inflammation marked by upregulated translocator protein (PBR-TSPO), which can be quantified with specific PET tracers.

Procedures:

We performed a feasibility study to prospectively evaluate [¹¹C]methionine and [¹¹C]PBR28 using PET in 5 patients with 7 previously SRS-treated brain metastases demonstrating regrowth to differentiate TR from RN.

Results:

Sequential imaging with dual tracers was well-tolerated. [¹¹C]methionine was accurate for detecting pathologically confirmed TR in 7/7 lesions, whereas [¹¹C]PBR28 was only accurate in 3/7 lesions. Tumor PBR-TSPO expression was elevated in both melanoma and lung cancer cells, contributing to lack of specificity of [¹¹C]PBR28-PET.

Conclusion:

Sequential use of PET tracers is safe and effective. [¹¹C]Methionine was a reliable TR marker, but [¹¹C]PBR28 was not a reliable marker of RN. Studies are needed to determine the causes of post-radiation inflammation and identify specific markers of RN to improve diagnostic imaging.

Elective Colectomy in a Patient with Active Ulcerative Colitis and Metastatic Melanoma Enabling Successful Treatment with Immune Checkpoint Inhibitors

Checkpoint inhibitor immunotherapy has significantly advanced treatment of a growing number of advanced malignancies. A consequences of immune system activation that leads to tumor cell destruction by checkpoint inhibitor therapy is the development of immune-related adverse events, some of which can be life threatening. There are limited data on the use of checkpoint inhibitor therapy in patients with preexisting autoimmunity owing to concerns that underlying autoimmune disease may be exacerbated by checkpoint inhibitor treatment. Decisions to treat these patients are made after careful consideration of the risks and benefits of treatment. We describe a patient with active and severe ulcerative colitis with metastatic melanoma who underwent elective colectomy prior to initiation of anti-PD-1 and anti-CTLA-4. The patient had excellent tumor response without flare of his ulcerative colitis suggesting that in select patients with high-risk inflammatory bowel disease, elective colectomy may be an effective treatment option.

Bempegaldesleukin (NKTR-214) plus Nivolumab in Patients with Advanced Solid Tumors: Phase I Dose-Escalation Study of Safety, Efficacy, and Immune Activation (PIVOT-02)

This single-arm, phase I dose-escalation trial (NCT02983045) evaluated bempegaldesleukin (NKTR-214/BEMPEG), a CD122-preferential IL2 pathway agonist, plus nivolumab in 38 patients with selected immunotherapy-naïve advanced solid tumors (melanoma, renal cell carcinoma, and non-small cell lung cancer). Three dose-limiting toxicities were reported in 2 of 17 patients during dose escalation [hypotension (n = 1), hyperglycemia (n = 1), metabolic acidosis (n = 1)]. The most common treatment-related adverse events (TRAE) were flu-like symptoms (86.8%), rash (78.9%), fatigue (73.7%), and pruritus (52.6%). Eight patients (21.1%) experienced grade 3/4 TRAEs; there were no treatment-related deaths. Total objective response rate across tumor types and dose cohorts was 59.5% (22/37), with 7 complete responses (18.9%). Cellular and gene expression analysis of longitudinal tumor biopsies revealed increased infiltration, activation, and cytotoxicity of CD8⁺ T cells, without regulatory T-cell enhancement. At the recommended phase II dose, BEMPEG 0.006 mg/kg plus nivolumab 360 mg every 3 weeks, the combination was well tolerated and demonstrated encouraging clinical activity irrespective of baseline PD-L1 status. SIGNIFICANCE: These data show that BEMPEG can be successfully combined with a checkpoint inhibitor as dual immunotherapy for a range of advanced solid tumors. Efficacy was observed regardless of baseline PD-L1 status and baseline levels of tumor-infiltrating lymphocytes, suggesting therapeutic potential for patients with poor prognostic risk factors for response to PD-1/PD-L1 blockade.See related commentary by Rouanne et al., p. 1097.This article is highlighted in the In This Issue feature, p. 1079.

Transcriptomic Hallmarks of Tumor Plasticity and Stromal Interactions in Brain Metastasis

The brain is a major site of relapse for several cancers, yet deciphering the mechanisms of brain metastasis remains a challenge because of the complexity of the brain tumor microenvironment (TME). To define the molecular landscape of brain metastasis from intact tissue in vivo, we employ an RNA-sequencing-based approach, which leverages the transcriptome of xenografts and distinguishes tumor cell and stromal gene expression with improved sensitivity and accuracy. Our data reveal shifts in epithelial and neuronal-like lineage programs in malignant cells as they adapt to the brain TME and the reciprocal neuroinflammatory response of the stroma. We identify several transcriptional hallmarks of metastasis that are specific to particular regions of the brain, induced across multiple tumor types, and confirmed in syngeneic models and patient biopsies. These data may serve as a resource for exploring mechanisms of TME co-adaptation within, as well as across, different subtypes of brain metastasis.

A phase I, open-label, multicenter, single-dose escalation and multi-dose study of a monoclonal antibody targeting CEACAM1 in subjects with selected advanced or recurrent malignancies

3094

Background: The carcinomembryonic antigen cell adhesion molecule 1 (CEACAM1, CD66a) is a member of the CEA gene family. CEACAM1 interacts homophilically and heterophilically with CEACAM5, and is involved in various anti-proliferative activities. CEACAM1 is expressed on a variety of epithelial and hematological cells, including multiple types of cancer and activated lymphocytes. High CEACAM1 expression in some tumor types is known to be associated with poor disease prognosis. Recently it was demonstrated CEACAM1 is co-expressed on exhausted lymphocytes with other immune checkpoints such as TIM-3 and may regulate downstream activity. CM24 is a novel humanized α-CEACAM1-specific antibody with nM affinity to the N terminal domain of CEACAM1, which blocks intercellular CEACAM1 interactions. Methods: The primary objective was to test the safety and tolerability of CM24 in adult patients with advanced or recurrent cancer. Secondary objectives included assessment of CM24 PK and PD profiles, anti-tumor response and the recommended Phase 2 dose. Patient received IV infusion of CM24 at 7 dose levels ranging between 0.01 and 10 mg/kg in a cycle of 4 doses administered q2wks followed by a 6-week observation only period and additional 6 cycles. Results: 27 patients (median pretreatment of 4 prior regimens; range 2-8, 11 colorectal, 7 melanoma, 4 ovarian, 3 gastric, 2 NSCLC; 13 males, 14 females, mean age of 60 years), were included. Treatment with CM-24 was overall well-tolerated without DLTs up to 10 mg/kg. The most frequent AE was grade 1-3 increased alanine aminotransferase (7 subjects) and the most severe AE was grade 3/4 increase in gamma-glutamyltransferase (4 subjects). Drug-related AEs were observed in 63% of the subjects with grade 3-5 occurred in 3.7%. Eight subjects (29.6%) had stable disease as the best overall response. Median overall survival was 4 (3.4, 8.0) and 6.2 (2.7, 10.2) months for the 3 and 10 mg/kg doses, suggesting dose response. Cmax, AUC and t1/2 increased with increasing dose with the longest t1/2 of 11.2 days obtained at 10mg/kg. The average target occupancy of CM24 at 3mg/kg and 10mg/kg were 75% and 93%, respectively. Conclusions: PK and target-mediated drug disposition analysis suggest that doses higher than 10mg/kg are needed for target saturation at a q2 week regimen while a q3 week regimen is less optimal. A phase 1/2 clinical trial testing CM24 in combination with anti-PD-1 therapy in patients with NSCLC including assessment of CEACAM1 expression is warranted. Clinical trial information: NCT02346955 .

FRACTION-RCC: Innovative, high-throughput assessment of nivolumab + ipilimumab for treatment-refractory advanced renal cell carcinoma (aRCC)

5007

Background: The immuno-oncology (I-O) combination nivolumab + ipilimumab (NIVO+IPI) is approved for first-line (1L) and NIVO is approved for second-line treatment post TKI therapy in aRCC. The open-label, randomized, phase 2 Fast Real-Time Assessment of Combination Therapies in Immuno-Oncology (FRACTION-RCC; NCT02996110) platform study has an adaptive design allowing rapid evaluation of I-O therapies, including NIVO+IPI or other investigational combinations. This FRACTION analysis reports preliminary outcomes with NIVO+IPI in aRCC pts after progression on checkpoint inhibitor therapy. Methods: All pts, except 1, had previously received and progressed on checkpoint inhibitor treatment. Pts received NIVO+IPI (NIVO 3 mg/kg + IPI 1 mg/kg Q3W ×4, then after 6 weeks, NIVO 480 mg Q4W), up to 2 years or until progression, toxicity, or protocol-specified discontinuation. Primary endpoints were confirmed objective response rate (ORR; per investigator using RECIST v1.1), duration of response (DOR), and progression-free survival probability at week 24. Safety outcomes were reported. Results: 46 pts were randomized to NIVO+IPI. Pts had 0 (n = 1), 1 (n = 10), 2 (n = 12), 3 (n = 10), or ≥4 (n = 13) prior lines of therapy. All pretreated pts had prior anti-PD-(L)1-, none had prior anti-CTLA-4- therapy, and 37 had prior TKI-based therapy; 45 pts progressed on anti-PD-(L)1 as the most recent therapy. Most pts had clear cell aRCC (n = 44). After a median study follow-up of 8.9 months, ORR was 15.2%; no pts achieved complete response and 7 achieved partial response. DOR ranged from 2–19+ months (n = 7); 5 pts had ongoing response. Six of 7 responders had received ≥2 prior lines of therapy. Any-grade treatment-related adverse events (AEs) were reported in 36 pts (78.3%; fatigue, rash [both 19.6%], and diarrhea [17.4%] were most common). Grade 3–4 treatment-related AEs were reported in 13 pts (28.3%; diarrhea [8.7%], ↑amylase and ↑lipase [both 6.5%] were most common). Treatment-related immune-mediated AEs of any grade were reported in 22 pts (47.8%; rash [19.6%], diarrhea [17.4%], and ↑alanine aminotransferase [8.7%]). No treatment-related deaths were reported. Updated and expanded results with an additional 3 months of follow-up will be presented. Conclusions: These results suggest that NIVO+IPI may provide durable partial response in some pts with prior progression on checkpoint inhibitors, including some heavily pretreated pts. The safety profile of NIVO+IPI in FRACTION pts was similar to historic data in aRCC with this combination. Clinical trial information: NCT02996110 .

A phase Ib study of nivolumab in patients with autoimmune disorders and advanced malignancies (AIM-NIVO)

TPS3158

Background: Immune checkpoint inhibitors (ICI) such as anti-PD-1/PD-L1 antibodies have become a pivotal approach to cancer therapy. Nivolumab is an anti-PD1 antibody approved for an increasing number of solid tumors and hematological malignancies. However, patients (pts) with history of autoimmune disorders are excluded from the majority of clinical trials testing ICI. Consequently, the risks of flares and worsening of pre-existing autoimmune disorders in pts with tumor types who otherwise stand to benefit from ICI therapy are largely unknown, posing a challenge for oncologists. We are conducting a phase Ib study to test the hypothesis that nivolumab can be safely administered to pts with varying severity of Dermatomyositis, Systemic Sclerosis, Rheumatoid Arthritis, Systemic Lupus Erythematosus, Inflammatory Bowel Disease, Multiple Sclerosis, Sjögren's Syndrome and Other Autoimmune Disorders (AIM-Nivo). Methods: AIM-Nivo is an open-label, multi-center ongoing phase Ib study with nivolumab 480mg IV every 28 days in pts with autoimmune diseases and advanced malignancies (NCT03816345). The study has autoimmune disease-specific cohorts overseen by a multidisciplinary group of experts. The primary objective is to assess the overall safety and toxicity profile of nivolumab in pts with autoimmune disorders and advanced malignancies. Secondary objectives are to evaluate the antitumor efficacy, the impact of nivolumab on the autoimmune disease severity indices, and to explore potential biomarkers of response, resistance or toxicity. Key overall inclusion criteria include age ≥18 years, histologically confirmed advanced malignancies in which ICI are approved or have shown clinical activity. Key overall exclusion criteria include prior therapy with anti-PD-1/PD-L1 antibodies. Specific eligibility criteria are defined for each disease-specific cohort. For each autoimmune disorder, severity level of the disease as defined by disease-specific severity indices will be assessed, and up to a total of 12 pts will be included in each disease cohort at each severity level. Primary endpoints are dose-limiting toxicities, adverse events (AEs) and serious AEs. Continuous monitoring of toxicity will be conducted. Key secondary endpoints are best objective response, progression free and overall survival and cohort specific tumor tissue, blood and non-tumor tissue-based biomarkers. The AIM-Nivo trial opened in May 2019 and is enrolling pts through the National Cancer Institute Experimental Therapeutics Clinical Trials Network (ETCTN). Clinical trial information: NCT03816345 .

Long-term follow up of lifileucel (LN-144) cryopreserved autologous tumor infiltrating lymphocyte therapy in patients with advanced melanoma progressed on multiple prior therapies

10006

Background: Treatment options are limited for patients with advanced melanoma who have progressed on checkpoint inhibitors and targeted therapies. Adoptive cell therapy using tumor-infiltrating lymphocytes (TIL) leverages and enhances the body’s natural defense against cancer and has shown durable responses in heavily pretreated melanoma patients. Methods: C-144-01 is a global Phase 2 open-label, multicenter study of efficacy & safety of lifileucel in patients with unresectable metastatic melanoma who have progressed on checkpoint inhibitors and BRAF/MEK inhibitors, if BRAFv600 mutant. We report on Cohort 2 (N = 66) patients who have received TIL. Tumors were resected at local institutions, processed in central GMP facilities for TIL production, manufactured, cryopreserved & shipped back to sites in a 22-day process. Therapy consisted of one week of lymphodepletion, a single lifileucel infusion, and up to 6 IL-2 doses. ORR was based on RECIST v1.1 by investigator assessment. Data cutoff was Feb 2, 2020. Results: Baseline characteristics: 3.3 mean prior therapies (anti-PD1 100%; anti-CTLA-4 80%; BRAF/MEK inhibitor 23%), high baseline tumor burden (106 mm mean target lesion sum of diameters), 44% liver/brain lesions, 40.9% LDH > ULN. ORR by investigator was 36.4% (2 CR, 22 PR) and DCR was 80.3%. Mean time to response was 1.9 months (range: 1.3-5.6). After a median study follow-up of 17.0 months, median DOR (mDOR) was still not reached. Six responders have progressed, 2 have died and 2 started other anti-cancer therapy without progression. The adverse event profile was consistent with the underlying advanced disease and the lymphodepletion and IL-2 regimens. Additional follow-up data will be available for presentation. Conclusions: Lifileucel treatment results in a 36.4% ORR and mDOR was not reached at 17.0 months of median study follow up in a heavily pretreated metastatic melanoma patients with high baseline disease burden who progressed on multiple prior therapies, including anti-PD1 and BRAF/MEK inhibitors, if BRAFv600 mutant. Clinical trial information: NCT02360579.

Pembrolizumab for management of patients with NSCLC and brain metastases: long-term results and biomarker analysis from a non-randomised, open-label, phase 2 trial

BACKGROUND

We did a phase 2 trial of pembrolizumab in patients with non-small-cell lung cancer (NSCLC) or melanoma with untreated brain metastases to determine the activity of PD-1 blockade in the CNS. Interim results were previously published, and we now report an updated analysis of the full NSCLC cohort.

METHODS

This was an open-label, phase 2 study of patients from the Yale Cancer Center (CT, USA). Eligible patients were at least 18 years of age with stage IV NSCLC with at least one brain metastasis 5-20 mm in size, not previously treated or progressing after previous radiotherapy, no neurological symptoms or corticosteroid requirement, and Eastern Cooperative Oncology Group performance status less than two. Modified Response Evaluation Criteria in Solid Tumors (mRECIST) criteria was used to evaluate CNS disease; systemic disease was not required for participation. Patients were treated with pembrolizumab 10 mg/kg intravenously every 2 weeks. Patients were in two cohorts: cohort 1 was for those with PD-L1 expression of at least 1% and cohort 2 was patients with PD-L1 less than 1% or unevaluable. The primary endpoint was the proportion of patients achieving a brain metastasis response (partial response or complete response, according to mRECIST). All treated patients were analysed for response and safety endpoints. This study is closed to accrual and is registered with ClinicalTrials.gov, NCT02085070.

FINDINGS

Between March 31, 2014, and May 21, 2018, 42 patients were treated. Median follow-up was 8·3 months (IQR 4·5-26·2). 11 (29·7% [95% CI 15·9-47·0]) of 37 patients in cohort 1 had a brain metastasis response. There were no responses in cohort 2. Grade 3-4 adverse events related to treatment included two patients with pneumonitis, and one each with constitutional symptoms, colitis, adrenal insufficiency, hyperglycaemia, and hypokalaemia. Treatment-related serious adverse events occurred in six (14%) of 42 patients and were pneumonitis (n=2), acute kidney injury, colitis, hypokalaemia, and adrenal insufficiency (n=1 each). There were no treatment-related deaths.

INTERPRETATION

Pembrolizumab has activity in brain metastases from NSCLC with PD-L1 expression at least 1% and is safe in selected patients with untreated brain metastases. Further investigation of immunotherapy in patients with CNS disease from NSCLC is warranted.

FUNDING

Merck and the Yale Cancer Center.

PD-1/PD-L1 Blockers in NSCLC Brain Metastases: Challenging Paradigms and Clinical Practice

Immune checkpoint inhibitors (ICI) have revolutionized the management of advanced non-small cell lung cancer (NSCLC). However, most pivotal phase III trials systematically excluded patients with active brain metastases, precluding the generalization of the results. Although theoretically restricted from crossing the blood-brain barrier, the novel pharmacokinetic/pharmacodynamic profiles of anti-PD-1/PD-L1 drugs have prompted studies to evaluate their activity in patients with NSCLC with active central nervous system (CNS) involvement. Encouraging results have suggested that ICI could be active in the CNS in selected patients with driver-negative advanced NSCLC with high PD-L1 expression and low CNS disease burden. Single-agent CNS response rates around 30% have been reported. Beyond this particular setting, anti-PD-1/PD-L1 antibodies have been evaluated in patients receiving local therapy for brain metastases (BM), addressing concerns about potential neurologic toxicity risks associated with radiotherapy, more specifically, radionecrosis (RN). Accordingly, a variety of clinical and imaging strategies are being appropriately developed to evaluate tumor response and to rule out pseudoprogression or radionecrosis. Our purpose is to critically summarize the advances regarding the role of systemic anti-PD-1/PD-L1 antibodies for the treatment of NSCLC BM. Data were collected from the PubMed database, reference lists, and abstracts from the latest scientific meetings. Recent reports suggest anti-PD-1/PD-L1 agents are active in a subset of patients with NSCLC with BM showing acceptable toxicity. These advances are expected to change soon the management of these patients but additional research is required to address concerns regarding radionecrosis and the appropriate sequencing of local and systemic therapy combinations.

Defining tumor resistance to PD-1 pathway blockade: recommendations from the first meeting of the SITC Immunotherapy Resistance Taskforce

As the field of cancer immunotherapy continues to advance at a fast pace, treatment approaches and drug development are evolving rapidly to maximize patient benefit. New agents are commonly evaluated for activity in patients who had previously received a programmed death receptor 1 (PD-1)/programmed death-ligand 1 (PD-L1) inhibitor as standard of care or in an investigational study. However, because of the kinetics and patterns of response to PD-1/PD-L1 blockade, and the lack of consistency in the clinical definitions of resistance to therapy, the design of clinical trials of new agents and interpretation of results remains an important challenge. To address this unmet need, the Society for Immunotherapy of Cancer convened a multistakeholder taskforce-consisting of experts in cancer immunotherapy from academia, industry, and government-to generate consensus clinical definitions for resistance to PD-(L)1 inhibitors in three distinct scenarios: primary resistance, secondary resistance, and progression after treatment discontinuation. The taskforce generated consensus on several key issues such as the timeframes that delineate each type of resistance, the necessity for confirmatory scans, and identified caveats for each specific resistance classification. The goal of this effort is to provide guidance for clinical trial design and to support analyses of emerging molecular and cellular data surrounding mechanisms of resistance.

Survival after checkpoint inhibitors for metastatic acral, mucosal and uveal melanoma

BACKGROUND

Checkpoint inhibitors (CPIs) are thought to be effective against cutaneous melanoma in part because of the large burden of somatic mutations (neoantigens) generated from exposure to ultraviolet radiation. However, rare melanoma subtypes arising from acral skin, mucosal surfaces, and the uveal tract are largely sun-shielded. Genomic studies show these sun-shielded melanomas have a paucity of neoantigens and unique biology; they are thought to be largely resistant to immunotherapy. It has not been definitively shown that CPI improves survival in metastatic sun-shielded melanoma.

METHODS

We reviewed a single institutional experience using antibodies against CTLA-4, PD-1 and/or PD-L1 to treat patients with metastatic melanoma. Primary tumor histology was categorized as cutaneous, unknown, acral, mucosal, or uveal. We studied demographic data, treatment characteristics, and overall survival (OS) after CPI.

RESULTS

We treated 428 patients with metastatic melanoma from 2007 to 2019. Primary tumors were cutaneous in 283 (66%), unknown in 55 (13%), acral in 22 (5%), mucosal in 38 (9%), and uveal in 30 (7%). Patients with metastatic disease from cutaneous primary tumors had median OS after CPI of 45 months compared with 17 months for acral (p=0.047), 18 months for mucosal (p=0.003), and 12 months for uveal (p<0.001). For all patients with sun-shielded melanoma (n=90), first treatment with anti-PD-1 or anti-PD-L1 was followed by a median OS of 9 months compared with 18 months after anti-CTLA-4 (p=0.010) and 20 months after combination therapy (p=0.003). There were 21 patients who achieved actual 3-year survival; 20 received both anti-CTLA-4 and anti-PD-1, either sequentially or in combination. Over 80% of 3-year survivors with progressive disease were treated with local therapy after CPI.

CONCLUSIONS

Long survival in patients with metastatic melanoma from acral, mucosal, and uveal primary tumors was associated with receipt of both anti-CTLA-4 and anti-PD-1 antibodies. Complete responses were rare, and local therapy was frequently employed to control disease progression. While sun-shielded melanomas exhibit worse outcomes after CPI than cutaneous melanomas, with an aggressive multidisciplinary approach, 5-year survival is still possible for 25%-32% of these patients.

Complications associated with immunotherapy for brain metastases

PURPOSE OF REVIEW

Median survival after the diagnosis of brain metastases has historically been on the order of months. With the recent development of immune checkpoint inhibitors, intracranial activity and durable responses have been observed in brain metastases on multiple phase 2 clinical trials, which have primarily been conducted in patients with melanoma. Immune-related adverse events related to checkpoint inhibitor therapy of brain metastasis can present unique challenges for the clinician and underscore the need for a multidisciplinary team in the care of these patients. The goal of this review is to address the current knowledge, limitations of understanding, and future directions in research regarding immune therapy trials and neurologic toxicities based on retrospective, prospective, and case studies.

RECENT FINDINGS

Immune therapy has the potential to exacerbate symptomatic edema and increase the risk of radiation necrosis in previously irradiated lesions. Neurologic toxicities will likely increase in prevalence as more patients with brain metastatic disease are eligible for immune therapy.

SUMMARY

An improved understanding and heightened awareness of the unique neurologic toxicities that impact this patient group is vital for mitigating treatment-related morbidity and mortality.

PLEKHA5 regulates tumor growth in metastatic melanoma

BACKGROUND

PLEKHA5 has previously been identified as a novel molecule implicated in melanoma brain metastasis, a disease that continues to portend a poor prognosis. The aim of this study was to further investigate the functional role of PLEKHA5 in disseminated melanoma.

METHODS

The impact of PLEKHA5 on proliferation and tumor growth was examined in vitro and in melanoma xenograft models, including brain-tropic melanomas (melanomas tending to disseminate to the brain). In vitro loss- and gain-of-function studies were used to explore the underlying mechanisms of PLEKHA5-mediated tumor growth and the crosstalk between PLEKHA5 and PI3K/AKT/mTOR or MAPK/ERK signaling. The clinical relevance of PLEKHA5 dysregulation was further investigated in a cohort of matched cranial and extracranial melanoma metastases.

RESULTS

PLEKHA5 stable knockdown negatively regulated cell proliferation by inhibiting the G₁ -to-S cell cycle transition, which coincided with upregulation of the cell cycle regulator PDCD4. Conversely, ectopic PLEKHA5 expression exhibited the inverse effect. PLEKHA5 knockdown significantly inhibited tumor growth, whereas its overexpression upregulated the growth of tumors, which was induced by cranial and subcutaneous inoculation of cells in nude mice. PLEKHA5 modulation affected PDCD4 protein stability and was coupled with changes in PI3K/AKT/mTOR pathway signaling. High PDCD4 expression in cerebral specimens was associated with better overall survival.

CONCLUSIONS

This study further supports the role of PLEKHA5 as a regulator of melanoma growth at distant sites, including the brain. Furthermore, the results highlight the significance of PDCD4 dysregulation in disseminated melanoma and implicate PDCD4 as a possible causal link between PLEKHA5 and cell proliferation and growth.

RBTT-07. A PHASE 2 TRIAL OF PEMBROLIZUMAB AND BEVACIZUMAB IN MELANOMA BRAIN MET PATIENTS

BACKGROUND

Pembro monotherapy (NCT02085070) produces responses in 26% of (mel) BrM pts. VEGF inhibitors (VEGFi) enhance anti-PD-1 activity in preclinicals. Therefore, we initiated a phase 2 study (NCT02681549) of pembro plus bev in BrM pts.

METHODS

Eligibility includes advanced mel, > 1 asymptomatic BrM, diameter 5-20mm, no steroids, no prior PD-1/PD-L1 or VEGFi. Pembro IV 200mg q3 wks for < yrs with bev 7.5mg/kg for the first 4 cycles. Primary endpoint was BrM RR by modified RECIST.

RESULTS

Between 8/2016 - 1/2019, 20 mel pts were enrolled. 60% were male mdn age 62;ECOG PS was 0 in 16 and 1 in 4 pts; LDH > ULN in 20%; 4 (20%); 10 were BRAFmt; 8 pts (40%) had > 4 untreated BrM. 12 had a BrM response (7 CR, 5 PR); 1 each with SD, unevaluable and an unconfirmed PR, for an ORR BrM of 60% (12/20). All responses lasted 7+ to 30+ mths. 16 pts are alive. AEs attributable to bev include hypertension, microscopic diverticular perforation and wound dehiscence (1 pt each, all resolved). 1 had mucositis attributed to Pembro. Three d/c’d treatment for grade 3 ALT elevation. Cerebral edema decreased in all pts with baseline edema.

CONCLUSIONS

Pembro plus bev demonstrates promising activity in melanoma BrMs compared to pembro alone. The pre-specified primary endpoint (> 4 BrM responses/20) was met, supporting further study. The toxicity profile was similar to pembro alone.

Deep Learning Based on Standard H&E Images of Primary Melanoma Tumors Identifies Patients at Risk for Visceral Recurrence and Death

PURPOSE

Biomarkers for disease-specific survival (DSS) in early-stage melanoma are needed to select patients for adjuvant immunotherapy and accelerate clinical trial design. We present a pathology-based computational method using a deep neural network architecture for DSS prediction.

EXPERIMENTAL DESIGN

The model was trained on 108 patients from four institutions and tested on 104 patients from Yale School of Medicine (YSM, New Haven, CT). A receiver operating characteristic (ROC) curve was generated on the basis of vote aggregation of individual image sequences, an optimized cutoff was selected, and the computational model was tested on a third independent population of 51 patients from Geisinger Health Systems (GHS).

RESULTS

Area under the curve (AUC) in the YSM patients was 0.905 (P < 0.0001). AUC in the GHS patients was 0.880 (P < 0.0001). Using the cutoff selected in the YSM cohort, the computational model predicted DSS in the GHS cohort based on Kaplan-Meier (KM) analysis (P < 0.0001).

CONCLUSIONS

The novel method presented is applicable to digital images, obviating the need for sample shipment and manipulation and representing a practical advance over current genetic and IHC-based methods.

Closed system RT-qPCR as a potential companion diagnostic test for immunotherapy outcome in metastatic melanoma

Background

In melanoma, there is no companion diagnostic test to predict response to programmed cell death 1 (PD-1) axis immune checkpoint inhibitor (ICI) therapy. In the adjuvant setting, only one in five patients may benefit from ICI, so a biomarker is needed to select those that may or may not benefit. Here, we test a new 4-gene multiplex immunotherapy panel with research use only (RUO) prototype mRNA expression profile on the GeneXpert closed system using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) for association with clinical benefit after treatment with ICI therapy in metastatic melanoma patients.

Methods

Pretreatment formalin-fixed paraffin-embedded (FFPE) tissue sections from melanoma patients treated with anti-PD-1 therapy (pembrolizumab, nivolumab, or ipilimumab plus nivolumab) between 2011 and 17 were selected from the Yale Pathology archives. FFPE sections were macrodissected to enrich for tumor for quantitative assessment of CD274 (PD-L1), PDCD1LG2 (PD-L2), CD8A, and IRF1 by RT-qPCR multiplex mRNA panel. Multiplex panel transcript levels were correlated with clinical benefit (complete response [CR], partial response [PR], stable disease [SD]); disease outcomes (progression-free survival [PFS] and overall survival [OS]); and protein levels assessed by quantitative immunofluorescence (QIF).

Results

Transcript levels were significantly higher in responders (CR/PR/SD) than in nonresponders (PD) for CD8A (p = 0.0001) and IRF1 (p = 0.0019). PFS was strongly associated with high CD274 (p = 0.0046), PDCD1LG2 (p = 0.0039), CD8A (p = 0.0002), and IRF1 (p = 0.0030) mRNA expression. Similar associations were observed for OS with high CD274 (p = 0.0004), CD8A (p = 0.0030), and IRF1 (p = 0.0096) mRNA expression. Multivariate analyses revealed significant PFS and OS associations with immunotherapy panel markers independent of baseline variables. Exploratory analyses revealed a novel significant association of high combined CD274 & PDCD1LG2 (L1/L2) transcript expression with PFS (p < 0.0001) and OS (p = 0.0011), which remained significant at a multivariate level for both PFS (HR = 0.31) and OS (HR = 0.39).

Conclusions

Individual immunotherapy panel markers CD274, PDCD1LG2, CD8A, IRF1 and a combined L1/L2 mRNA levels show promising associations with melanoma immunotherapy outcome. The turnaround time of the test (2 h) and easy standardization of the platform makes this an attractive approach for further study in the search for predictive biomarkers for ICI.

Treatment-Free Survival: A Novel Outcome Measure of the Effects of Immune Checkpoint Inhibition-A Pooled Analysis of Patients With Advanced Melanoma

PURPOSE

Outcome measures that comprehensively capture attributes of immuno-oncology agents, including prolonged treatment-free time and persistent treatment-related adverse events (TRAEs), are needed to complement conventional survival end points.

METHODS

We pooled data from the CheckMate 067 and 069 clinical trials of nivolumab and ipilimumab, as monotherapies or in combination, for patients with advanced melanoma. Treatment-free survival (TFS) was defined as the area between Kaplan-Meier curves for two conventional time-to-event end points, each defined from random assignment: time to immune checkpoint inhibitor (ICI) protocol therapy cessation and time to subsequent systemic therapy initiation or death. TFS was partitioned as time with and without toxicity by a third end point, time to cessation of both ICI therapy and toxicity. Toxicity included persistent and late-onset grade 3 or higher TRAEs. The area under each Kaplan-Meier curve was estimated by the 36-month restricted mean time.

RESULTS

At 36 months, many of the 1,077 patients who initiated ICI therapy were surviving free of subsequent therapy initiation (47% nivolumab plus ipilimumab, 37% nivolumab, 15% ipilimumab). The restricted mean TFS was longer for nivolumab plus ipilimumab (11.1 months) compared with nivolumab (4.6 months; difference, 6.5 months; 95% CI, 5.0 to 8.0 months) or ipilimumab (8.7 months; difference, 2.4 months; 95% CI, 0.8 to 4.1 months); restricted mean TFS represented 31% (3% with and 28% without toxicity), 13% (1% and 11%), and 24% (less than 1% and 23%) of the 36-month period, respectively, in the three treatment groups. TFS without toxicity was longer for nivolumab plus ipilimumab than nivolumab (difference, 6.0 months) or ipilimumab (difference, 1.7 months).

CONCLUSION

The analysis of TFS between ICI cessation and subsequent therapy initiation revealed longer TFS without toxicity for patients with advanced melanoma who received nivolumab plus ipilimumab compared with nivolumab or ipilimumab. Regardless of treatment, a small proportion of the TFS involved grade 3 or higher TRAEs.

Perilesional edema in brain metastases: potential causes and implications for treatment with immune therapy

Background

Little is known about tumor-associated vasogenic edema in brain metastasis, yet it causes significant morbidity and mortality. Our purpose was to characterize edema in patients treated with anti-PD-1 and to study potential causes of vessel leakage in humans and in pre-clinical models.

Methods

We analyzed tumor and edema volume in 18 non-small cell lung (NSCLC) and 18 melanoma patients with untreated brain metastases treated with pembrolizumab on a phase II clinical trial. Melanoma brain metastases were stained with anti-CD34 to assess vessel density and its association with edema. We employed an in vitro model of the blood-brain barrier using short-term cultures from melanoma brain and extracranial metastases to determine tight junction resistance as a measure of vessel leakiness.

Results

Edema volumes are similar in NSCLC and melanoma brain metastases. While larger tumors tended to have more edema, the correlation was weak (R² = 0.30). Patients responding to pembrolizumab had concurrent shrinkage of edema volume and vice versa (R² = 0.81). Vessel density was independent of the degree of edema (R² = 0.037). Melanoma brain metastasis cells in culture caused loss of tight junction resistance in an in vitro blood-brain barrier model system in some cases, whereas extracerebral cell cultures did not.

Conclusions

Edema itself should not preclude using anti-PD-1 with caution, as sensitive tumors have resultant decreases in edema, and anti-PD-1 itself does not exacerbate edema in sensitive tumors. Additional factors aside from tumor mass effect and vessel density cause perilesional edema. Melanoma cells themselves can cause decline in tight junction resistance in a system void of immune cells, suggesting they secrete factors that cause leakiness, which might be harnessed for pharmacologic targeting in patients with significant perilesional edema.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0684-z) contains supplementary material, which is available to authorized users.

Patterns of failure after immunotherapy with checkpoint inhibitors predict durable progression-free survival after local therapy for metastatic melanoma

BACKGROUND

Checkpoint inhibitors (CPI) have revolutionized the treatment of metastatic melanoma, but most patients treated with CPI eventually develop progressive disease. Local therapy including surgery, ablation or stereotactic body radiotherapy (SBRT) may be useful to manage limited progression, but criteria for patient selection have not been established. Previous work has suggested progression-free survival (PFS) after local therapy is associated with patterns of immunotherapy failure, but this has not been studied in patients treated with CPI.

METHODS

We analyzed clinical data from patients with metastatic melanoma who were treated with antibodies against CTLA-4, PD-1 or PD-L1, either as single-agent or combination therapy, and identified those who had disease progression in 1 to 3 sites managed with local therapy. Patterns of CPI failure were designated by independent radiological review as growth of established metastases or appearance of new metastases. Local therapy for diagnosis, palliation or CNS metastases was excluded.

RESULTS

Four hundred twenty-eight patients with metastatic melanoma received treatment with CPI from 2007 to 2018. Seventy-seven have ongoing complete responses while 69 died within 6 months of starting CPI; of the remaining 282 patients, 52 (18%) were treated with local therapy meeting our inclusion criteria. Local therapy to achieve no evidence of disease (NED) was associated with three-year progression-free survival (PFS) of 31% and five-year disease-specific survival (DSS) of 60%. Stratified by patterns of failure, patients with progression in established tumors had three-year PFS of 70%, while those with new metastases had three-year PFS of 6% (P = 0.001). Five-year DSS after local therapy was 93% versus 31%, respectively (P = 0.046).

CONCLUSIONS

Local therapy for oligoprogression after CPI can result in durable PFS in selected patients. We observed that patterns of failure seen during or after CPI treatment are strongly associated with PFS after local therapy, and may represent a useful criterion for patient selection. This experience suggests there may be an increased role for local therapy in patients being treated with immunotherapy.

Multiplex quantitative analysis of cancer-associated fibroblasts and immunotherapy outcome in metastatic melanoma

Background

The cancer-associated fibroblast (CAF) population is implicated in immune dysregulation. Here, we test the hypothesis that CAF profiles in pretreatment tumor specimens are associated with response to immune checkpoint blockade of programmed cell death 1 (PD-1).

Methods

Pretreatment whole tissue sections from 117 melanoma patients treated with anti-PD-1 therapy were assessed by multiplex immunofluorescence to detect CAFs defined by Thy1, smooth muscle actin (SMA), and fibroblast activation protein (FAP). Two independent image analysis technologies were used: inForm software (PerkinElmer) to quantify cell counts, and AQUA™ to measure protein by quantitative immunofluorescence (QIF). CAF parameters by both methodologies were assessed for association with previously measured immune markers (CD3, CD4, CD8, CD20, CD68, PD-L1), best overall response, progression-free survival (PFS), and overall survival (OS).

Results

CAF parameters, by cell counts or QIF, did not correlate with immune markers nor with best overall response. However, both Thy1 and FAP cell counts had significant positive associations with PFS (all P < 0.05) and OS (all P < 0.003). SMA cell counts showed negative associations with outcome in anti-PD-1 treated patients. Similar associations were not observed in a control cohort of historical melanoma patients predating immunotherapy. Instead, FAP was a negative prognostic biomarker (P = 0.01) in the absence of immunotherapy. Multivariable analyses revealed significant PFS and OS associations with the CAF parameters were independent of baseline variables.

Conclusions

Pretreatment CAF profiles are associated with melanoma immunotherapy outcome. Multiplex CAF analysis has potential as an objective companion diagnostic in immuno-oncology.

Electronic supplementary material

The online version of this article (10.1186/s40425-019-0675-0) contains supplementary material, which is available to authorized users.

Abstract 3142: A CD274, PDCD1LG2, CD8A, and IRF1 multiplex in a closed system RT-qPCR panel and immunotherapy outcome in metastatic melanoma

Background: In melanoma, there is no companion diagnostic test to predict response to programmed cell death 1 (PD-1) axis immune checkpoint inhibitor therapy (ICI). In the adjuvant setting, only 1 in 5 patients may benefit from ICI, so biomarker is needed to select those that may or may not benefit. Candidate techniques for the assessment of predictive markers include immunohistochemistry (IHC), multiplex fluorescence, genome sequencing, and RNA expression profiles. Here we test a new 4-gene research use only (RUO)* prototype mRNA expression profile on the GeneXpert closed system using real-time quantitative reverse transcription polymerase chain reaction (RT-qPCR) for association with clinical benefit after treatment with ICI in metastatic melanoma patients.

Methods: Pretreatment formalin-fixed paraffin-embedded (FFPE) tissue sections from melanoma patients treated with anti-PD-1 therapy (pembrolizumab, nivolumab, or ipilimumab plus nivolumab) between 2011-17 were selected from the Yale Pathology archives. FFPE sections were macrodissected to enrich for tumor for quantitative assessment of CD274 (PD-L1), PDCD1LG2 (PD-L2), CD8A, and IRF1 by RT-qPCR multiplex mRNA panel. Multiplex panel transcript levels were correlated with clinical benefit (CR/PR/SD); disease outcomes (progression-free survival, PFS and overall survival, OS); and protein levels assessed by quantitative immunofluorescence (QIF). Median values for each marker were used to define high versus low mRNA or protein expression groups. This study was approved by Yale Human Investigation IRB protocol ID 9505008219.

Results: Inter-transcript regression was observed among all four markers with R2 ranging from 0.20 to 0.51. Transcript levels were significantly higher in CR/PR/SD than in PD for CD8A (p = 0.0001) and IRF1 (p = 0.0019). PFS was strongly associated with high CD274 (p = 0.0046), PDCD1LG2 (p = 0.0039), CD8A (p = 0.0002), and IRF1 (p = 0.0030) mRNA expression. Similar associations were observed for OS with high CD274 (p = 0.0004), CD8A (p = 0.0030), and IRF1 (p = 0.0096) mRNA expression. Multivariate analyses revealed significant associations with OS independent of age, sex, stage, mutation, treatment, and prior ICI for CD274 (HR = 0.30), CD8A (HR = 0.40) and IRF1 mRNA (HR = 0.36). Similar PFS association with CD8A (HR = 0.39) and IRF1 (HR = 0.48) parameters were observed by multivariate analyses. Nonlinear exponential relationship was observed between transcript and protein levels for CD8A (R2 = 0.66) and IRF1 (R2 = 0.40).

Conclusions: Although tested in only a single melanoma cohort, CD274, CD8A and IRF1 mRNA levels show promising associations with outcome. The turnaround time of the test (2h) and easy standardization of the platform makes this an attractive approach for further study in the search for predictive biomarkers for ICI. *for Research Use Only - not approved or reviewed by any regulatory body

Citation Format: Swati Gupta, Leena McCann, Yvonne G.Y. Chan, Edwin W. Lai, Pok Fai Wong, James W. Smithy, Jodi Weidler, Brian Rhees, Michael Bates, Harriet M. Kluger, David L. Rimm. A CD274, PDCD1LG2, CD8A, and IRF1 multiplex in a closed system RT-qPCR panel and immunotherapy outcome in metastatic melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3142.

Abstract 4552: BMX-Seq as a new resource for deciphering the transcriptomic hallmarks of tumor plasticity and stromal interactions in brain metastasis

Purpose: Brain metastasis remains a major site of relapse for several cancer types. However, the molecular mechanisms of brain metastasis are largely unknown given the complex relationship between tumor cells and the surrounding brain tumor microenvironment (TME). To better characterize the tumor-stromal relationship in the context of brain metastasis, we have developed a Brain Metastatic RNA-Sequencing (BMX-Seq) approach, which leverages xenograft models and can distinguish between the transcriptomes of human tumor and mouse stroma gene expression in vivo. This resource provides an extensive molecular portrait of the co-adaptation of brain metastasis with the brain TME.

Methods: Following intra-arterial injection of the human, lung adenocarcinoma (LUAD), H2030-BrM3 cell model into athymic mice, metastatic brain tumors were macrodisasected, flash frozen and RNA extracted. Healthy brain regions, subcutaneous tumors and H2030-BrM3 cells grown in monolayer were harvested in parallel. Our BMX-Seq pipeline was engineered to analyze bulk xenograft tissue, which includes tumor lesions as well as surrounding stromal tissue. Species-specific Taqman primers and immunofluorescent (IF) staining were used to validate our BMX-Seq results. Models of melanoma and breast cancer brain metastasis were also included in this study.

Summary: In comparing the transcriptomic profiles of tumors grown in the brain as compared to other sites, we identify shifts in epithelial and neuronal-like gene expression programs in malignant cells and show such trends are reversible once tumor cells are removed from the brain TME. Genes involved in WNT signaling and cell projection were also upregulated across melanoma, lung and breast cancer types when cells were grown in the brain versus other sites. In describing the neuroinflammatory response of stromal regions directly surrounding brain lesions, our BMX-Seq analysis revealed increased expression of astrocyte and microglial enriched transcripts. We then utilized IF to confirm the elevated density of both of these cell types in areas directly surrounding and infiltrating tumor regions. We also detect significantly induced expression of stromal TIM3 in areas surrounding tumor lesions and in a model system devoid of T-Cells. Follow-up work revealed TIM3 is largely expressed and induced on tumor-associated macrophages (including microglia) within the tumor region, and we further validate such results in a syngeneic model system as well as in human, brain tissue.

Conclusions: We have developed a highly sensitive RNA-sequencing based approach that can accurately map the transcriptomic adaptation of brain metastatic tumor cells and the surrounding brain TME. We believe these data may serve as an invaluable resource to guide future discovery in CNS metastases.

Citation Format: Emily Wingrove, Zongzhi Z. Liu, Don X. Nguyen, Anna Arnal-Estape, Kiran D. Patel, Mary-Ann Melnick, Katerina Politi, Manuel Valiente, Harriet M. Kluger, Veronica L. Chiang. BMX-Seq as a new resource for deciphering the transcriptomic hallmarks of tumor plasticity and stromal interactions in brain metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 4552.