A phase 1 study of triple-targeted therapy with BRAF, MEK, and AKT inhibitors for patients with BRAF-mutated cancers

BACKGROUND

Aberrant PI3K/AKT signaling in BRAF-mutant cancers contributes to resistance to BRAF inhibitors. The authors examined dual MAPK and PI3K pathway inhibition in patients who had BRAF-mutated solid tumors (ClinicalTrials.gov identifier NCT01902173).

METHODS

Patients with BRAF V600E/V600K-mutant solid tumors received oral dabrafenib at 150 mg twice daily with dose escalation of oral uprosertib starting at 50 mg daily, or, in the triplet cohorts, with dose escalation of both oral trametinib starting at 1.5 mg daily and oral uprosertib starting at 25 mg daily. Dose-limiting toxicities (DLTs) were assessed within the first 56 days of treatment. Radiographic responses were assessed at 8-week intervals.

RESULTS

Twenty-seven patients (22 evaluable) were enrolled in parallel doublet and triplet cohorts. No DLTs were observed in the doublet cohorts (N = 7). One patient had a DLT at the maximum administered dose of triplet therapy (dabrafenib 150 mg twice daily and trametinib 2 mg daily plus uprosertib 75 mg daily). Three patients in the doublet cohorts had partial responses (including one who had BRAF inhibitor-resistant melanoma). Two patients in the triplet cohorts had a partial response, and one patient had an unconfirmed partial response. Pharmacokinetic data suggested reduced dabrafenib and dabrafenib metabolite exposure in patients who were also exposed to both trametinib and uprosertib, but not in whose who were exposed to uprosertib without trametinib.

CONCLUSIONS

Concomitant inhibition of both the MAPK and PI3K-AKT pathways for the treatment of BRAF-mutated cancers was well tolerated, leading to objective responses, but higher level drug-drug interactions affected exposure to dabrafenib and its metabolites.

Three-Year Overall Survival with Tebentafusp in Metastatic Uveal Melanoma

BACKGROUND

Tebentafusp, a T-cell receptor-bispecific molecule that targets glycoprotein 100 and CD3, is approved for adult patients who are positive for HLA-A*02:01 and have unresectable or metastatic uveal melanoma. The primary analysis in the present phase 3 trial supported a long-term survival benefit associated with the drug.

METHODS

We report the 3-year efficacy and safety results from our open-label, phase 3 trial in which HLA-A*02:01-positive patients with previously untreated metastatic uveal melanoma were randomly assigned in a 2:1 ratio to receive tebentafusp (tebentafusp group) or the investigator's choice of therapy with pembrolizumab, ipilimumab, or dacarbazine (control group), with randomization stratified according to the lactate dehydrogenase level. The primary end point was overall survival.

RESULTS

At a minimum follow-up of 36 months, median overall survival was 21.6 months in the tebentafusp group and 16.9 months in the control group (hazard ratio for death, 0.68; 95% confidence interval, 0.54 to 0.87). The estimated percentage of patients surviving at 3 years was 27% in the tebentafusp group and 18% in the control group. The most common treatment-related adverse events of any grade in the tebentafusp group were rash (83%), pyrexia (76%), pruritus (70%), and hypotension (38%). Most tebentafusp-related adverse events occurred early during treatment, and no new adverse events were observed with long-term administration. The percentage of patients who discontinued treatment because of adverse events continued to be low in both treatment groups (2% in the tebentafusp group and 5% in the control group). No treatment-related deaths occurred.

CONCLUSIONS

This 3-year analysis supported a continued long-term benefit of tebentafusp for overall survival among adult HLA-A*02:01-positive patients with previously untreated metastatic uveal melanoma. (Funded by Immunocore; IMCgp100-202 ClinicalTrials.gov number, NCT03070392; EudraCT number, 2015-003153-18.).

The PD-1- and LAG-3-targeting bispecific molecule tebotelimab in solid tumors and hematologic cancers: a phase 1 trial

Tebotelimab, a bispecific PD-1×LAG-3 DART molecule that blocks both PD-1 and LAG-3, was investigated for clinical safety and activity in a phase 1 dose-escalation and cohort-expansion clinical trial in patients with solid tumors or hematologic malignancies and disease progression on previous treatment. Primary endpoints were safety and maximum tolerated dose of tebotelimab when administered as a single agent (n = 269) or in combination with the anti-HER2 antibody margetuximab (n = 84). Secondary endpoints included anti-tumor activity. In patients with advanced cancer treated with tebotelimab monotherapy, 68% (184/269) experienced treatment-related adverse events (TRAEs; 22% were grade ≥3). No maximum tolerated dose was defined; the recommended phase 2 dose (RP2D) was 600 mg once every 2 weeks. There were tumor decreases in 34% (59/172) of response-evaluable patients in the dose-escalation cohorts, with objective responses in multiple solid tumor types, including PD-1-refractory disease, and in LAG-3+ non-Hodgkin lymphomas, including CAR-T refractory disease. To enhance potential anti-tumor responses, we tested margetuximab plus tebotelimab. In patients with HER2+ tumors treated with tebotelimab plus margetuximab, 74% (62/84) had TRAEs (17% were grade ≥3). The RP2D was 600 mg once every 3 weeks. The confirmed objective response rate in these patients was 19% (14/72), including responses in patients typically not responsive to anti-HER2/anti-PD-1 combination therapy. ClinicalTrials.gov identifier: NCT03219268 .

Randomized Phase 2 Clinical Trial of Olaratumab in Combination with Gemcitabine and Docetaxel in Advanced Soft Tissue Sarcomas

Gemcitabine plus docetaxel is an effective treatment regimen for advanced soft tissue sarcomas (STSs). However, the prognosis for patients remains poor, and thus there is an urgent medical need for novel and effective therapies to improve long-term outcomes. The aim of the ANNOUNCE 2 trial was to explore the addition of olaratumab (O) to gemcitabine (G) and docetaxel (D) for advanced STS. Adults with unresectable locally advanced/metastatic STS, ≤2 prior lines of systemic therapy, and ECOG PS 0-1 were eligible. In Phase 2, patients were randomized 1:1 from two cohorts (O-naïve and O-pretreated) to 21-day cycles of olaratumab (20 mg/kg Cycle 1 and 15 mg/kg other cycles, Days 1 and 8), gemcitabine (900 mg/m2, Days 1 and 8), and docetaxel (75 mg/m2, Day 8). The primary objective was overall survival (OS) in the O-naïve population (α level = 0.20). Secondary endpoints included OS (O-pretreated), other efficacy parameters, patient-reported outcomes, safety, pharmacokinetics, and immunogenicity. A total of 167 and 89 patients were enrolled in the O-naïve and O-pretreated cohorts, respectively. Baseline patient characteristics were well balanced. No statistically significant difference in OS was observed between the investigational vs. control arm for either cohort (O-naïve cohort: HR = 0.95 (95% CI: 0.64-1.40), p = 0.78, median OS, 16.8 vs. 18.0 months; O-pretreated cohort: HR = 0.67 (95% CI: 0.39-1.16), p = 0.15, median OS 19.8 vs. 17.3 months). Safety was manageable across treatment arms. There was no statistically significant difference in the primary endpoint of OS between the two arms in the O-naïve population, and therefore based on hierarchical evaluation no other outcomes in this study can be considered statistically significant. No new safety signals were observed.

Ipilimumab with or without nivolumab in PD-1 or PD-L1 blockade refractory metastatic melanoma: a randomized phase 2 trial

In this randomized phase 2 trial, blockade of cytotoxic T-lymphocyte protein 4 (CTLA-4) with continuation of programmed death protein 1 (PD-1) blockade in patients with metastatic melanoma who had received front-line anti-PD-1 or therapy against programmed cell death 1 ligand 1 and whose tumors progressed was tested in comparison with CTLA-4 blockade alone. Ninety-two eligible patients were randomly assigned in a 3:1 ratio to receive the combination of ipilimumab and nivolumab, or ipilimumab alone. The primary endpoint was progression-free survival. Secondary endpoints included the difference in CD8 T cell infiltrate among responding and nonresponding tumors, objective response rate, overall survival and toxicity. The combination of nivolumab and ipilimumab resulted in a statistically significant improvement in progression-free survival over ipilimumab (hazard ratio = 0.63, 90% confidence interval (CI) = 0.41-0.97, one-sided P = 0.04). Objective response rates were 28% (90% CI = 19-38%) and 9% (90% CI = 2-25%), respectively (one-sided P = 0.05). Grade 3 or higher treatment-related adverse events occurred in 57% and 35% of patients, respectively, which is consistent with the known toxicity profile of these regimens. The change in intratumoral CD8 T cell density observed in the present analysis did not reach statistical significance to support the formal hypothesis tested as a secondary endpoint. In conclusion, primary resistance to PD-1 blockade therapy can be reversed in some patients with the combination of CTLA-4 and PD-1 blockade. Clinicaltrials.gov identifier: NCT03033576 .

The landscape of drug sensitivity and resistance in sarcoma

Sarcomas are a family of rare malignancies composed of over 100 distinct histological subtypes. The rarity of sarcoma poses significant challenges in conducting clinical trials to identify effective therapies, to the point that many rarer subtypes of sarcoma do not have standard-of-care treatment. Even for established regimens, there can be substantial heterogeneity in responses. Overall, novel, personalized approaches for identifying effective treatments are needed to improve patient out-comes. Patient-derived tumor organoids (PDTOs) are clinically relevant models representative of the physiological behavior of tumors across an array of malignancies. Here, we use PDTOs as a tool to better understand the biology of individual tumors and characterize the landscape of drug resistance and sensitivity in sarcoma. We collected n=194 specimens from n=126 sarcoma patients, spanning 24 distinct subtypes. We characterized PDTOs established from over 120 biopsy, resection, and metastasectomy samples. We leveraged our organoid high-throughput drug screening pipeline to test the efficacy of chemotherapeutics, targeted agents, and combination therapies, with results available within a week from tissue collection. Sarcoma PDTOs showed patient-specific growth characteristics and subtype-specific histopathology. Organoid sensitivity correlated with diagnostic subtype, patient age at diagnosis, lesion type, prior treatment history, and disease trajectory for a subset of the compounds screened. We found 90 biological pathways that were implicated in response to treatment of bone and soft tissue sarcoma organoids. By comparing functional responses of organoids and genetic features of the tumors, we show how PDTO drug screening can provide an orthogonal set of information to facilitate optimal drug selection, avoid ineffective therapies, and mirror patient outcomes in sarcoma. In aggregate, we were able to identify at least one effective FDA-approved or NCCN-recommended regimen for 59% of the specimens tested, providing an estimate of the proportion of immediately actionable information identified through our pipeline.

Highlights

Standardized organoid culture preserve unique sarcoma histopathological featuresDrug screening on patient-derived sarcoma organoids provides sensitivity information that correlates with clinical features and yields actionable information for treatment guidanceHigh-throughput screenings provide orthogonal information to genetic sequencingSarcoma organoid response to treatment correlates with patient response to therapyLarge scale, functional precision medicine programs for rare cancers are feasible within a single institution.

Eganelisib, a First-in-Class PI3Kγ Inhibitor, in Patients with Advanced Solid Tumors: Results of the Phase 1/1b MARIO-1 Trial

PURPOSE

Eganelisib (IPI-549) is a first-in-class, orally administered, highly selective PI3Kγ inhibitor with antitumor activity alone and in combination with programmed cell death protein 1/ligand 1 (PD-1/PD-L1) inhibitors in preclinical studies. This phase 1/1b first-in-human, MAcrophage Reprogramming in Immuno-Oncology-1 (NCT02637531) study evaluated the safety and tolerability of once-daily eganelisib as monotherapy and in combination with nivolumab in patients with solid tumors.

PATIENTS AND METHODS

Dose-escalation cohorts received eganelisib 10-60 mg as monotherapy (n = 39) and 20-40 mg when combined with nivolumab (n = 180). Primary endpoints included incidence of dose-limiting toxicities (DLT) and adverse events (AE).

RESULTS

The most common treatment-related grade ≥3 toxicities with monotherapy were increased alanine aminotransferase (ALT; 18%), aspartate aminotransferase (AST; 18%), and alkaline phosphatase (5%). No DLTs occurred in the first 28 days; however, toxicities meeting DLT criteria (mostly grade 3 reversible hepatic enzyme elevations) occurred with eganelisib 60 mg in later treatment cycles. In combination, the most common treatment-related grade ≥3 toxicities were increased AST (13%) and increased ALT and rash (10%). Treatment-related serious AEs occurred in 5% of monotherapy patients (grade 4 bilirubin and hepatic enzyme increases in one patient each) and 13% in combination (pyrexia, rash, cytokine release syndrome, and infusion-related reaction in ≥2 patients each). Antitumor activity was observed in combination, including patients who had progressed on PD-1/PD-L1 inhibitors.

CONCLUSIONS

On the basis of the observed safety profile, eganelisib doses of 30 and 40 mg once daily in combination with PD-1/PD-L1 inhibitors were chosen for phase 2 study.

Neoadjuvant-Adjuvant or Adjuvant-Only Pembrolizumab in Advanced Melanoma

BACKGROUND

Whether pembrolizumab given both before surgery (neoadjuvant therapy) and after surgery (adjuvant therapy), as compared with pembrolizumab given as adjuvant therapy alone, would increase event-free survival among patients with resectable stage III or IV melanoma is unknown.

METHODS

In a phase 2 trial, we randomly assigned patients with clinically detectable, measurable stage IIIB to IVC melanoma that was amenable to surgical resection to three doses of neoadjuvant pembrolizumab, surgery, and 15 doses of adjuvant pembrolizumab (neoadjuvant-adjuvant group) or to surgery followed by pembrolizumab (200 mg intravenously every 3 weeks for a total of 18 doses) for approximately 1 year or until disease recurred or unacceptable toxic effects developed (adjuvant-only group). The primary end point was event-free survival in the intention-to-treat population. Events were defined as disease progression or toxic effects that precluded surgery; the inability to resect all gross disease; disease progression, surgical complications, or toxic effects of treatment that precluded the initiation of adjuvant therapy within 84 days after surgery; recurrence of melanoma after surgery; or death from any cause. Safety was also evaluated.

RESULTS

At a median follow-up of 14.7 months, the neoadjuvant-adjuvant group (154 patients) had significantly longer event-free survival than the adjuvant-only group (159 patients) (P = 0.004 by the log-rank test). In a landmark analysis, event-free survival at 2 years was 72% (95% confidence interval [CI], 64 to 80) in the neoadjuvant-adjuvant group and 49% (95% CI, 41 to 59) in the adjuvant-only group. The percentage of patients with treatment-related adverse events of grades 3 or higher during therapy was 12% in the neoadjuvant-adjuvant group and 14% in the adjuvant-only group.

CONCLUSIONS

Among patients with resectable stage III or IV melanoma, event-free survival was significantly longer among those who received pembrolizumab both before and after surgery than among those who received adjuvant pembrolizumab alone. No new toxic effects were identified. (Funded by the National Cancer Institute and Merck Sharp and Dohme; S1801 ClinicalTrials.gov number, NCT03698019.).

Non-viral precision T cell receptor replacement for personalized cell therapy

T cell receptors (TCRs) enable T cells to specifically recognize mutations in cancer cells1-3. Here we developed a clinical-grade approach based on CRISPR-Cas9 non-viral precision genome-editing to simultaneously knockout the two endogenous TCR genes TRAC (which encodes TCRα) and TRBC (which encodes TCRβ). We also inserted into the TRAC locus two chains of a neoantigen-specific TCR (neoTCR) isolated from circulating T cells of patients. The neoTCRs were isolated using a personalized library of soluble predicted neoantigen-HLA capture reagents. Sixteen patients with different refractory solid cancers received up to three distinct neoTCR transgenic cell products. Each product expressed a patient-specific neoTCR and was administered in a cell-dose-escalation, first-in-human phase I clinical trial ( NCT03970382 ). One patient had grade 1 cytokine release syndrome and one patient had grade 3 encephalitis. All participants had the expected side effects from the lymphodepleting chemotherapy. Five patients had stable disease and the other eleven had disease progression as the best response on the therapy. neoTCR transgenic T cells were detected in tumour biopsy samples after infusion at frequencies higher than the native TCRs before infusion. This study demonstrates the feasibility of isolating and cloning multiple TCRs that recognize mutational neoantigens. Moreover, simultaneous knockout of the endogenous TCR and knock-in of neoTCRs using single-step, non-viral precision genome-editing are achieved. The manufacture of neoTCR engineered T cells at clinical grade, the safety of infusing up to three gene-edited neoTCR T cell products and the ability of the transgenic T cells to traffic to the tumours of patients are also demonstrated.

Neoantigen-targeted CD8+ T cell responses with PD-1 blockade therapy

Neoantigens are peptides derived from non-synonymous mutations presented by human leukocyte antigens (HLAs), which are recognized by antitumour T cells1-14. The large HLA allele diversity and limiting clinical samples have restricted the study of the landscape of neoantigen-targeted T cell responses in patients over their treatment course. Here we applied recently developed technologies15-17 to capture neoantigen-specific T cells from blood and tumours from patients with metastatic melanoma with or without response to anti-programmed death receptor 1 (PD-1) immunotherapy. We generated personalized libraries of neoantigen-HLA capture reagents to single-cell isolate the T cells and clone their T cell receptors (neoTCRs). Multiple T cells with different neoTCR sequences (T cell clonotypes) recognized a limited number of mutations in samples from seven patients with long-lasting clinical responses. These neoTCR clonotypes were recurrently detected over time in the blood and tumour. Samples from four patients with no response to anti-PD-1 also demonstrated neoantigen-specific T cell responses in the blood and tumour to a restricted number of mutations with lower TCR polyclonality and were not recurrently detected in sequential samples. Reconstitution of the neoTCRs in donor T cells using non-viral CRISPR-Cas9 gene editing demonstrated specific recognition and cytotoxicity to patient-matched melanoma cell lines. Thus, effective anti-PD-1 immunotherapy is associated with the presence of polyclonal CD8+ T cells in the tumour and blood specific for a limited number of immunodominant mutations, which are recurrently recognized over time.

Combination Dabrafenib and Trametinib Versus Combination Nivolumab and Ipilimumab for Patients With Advanced BRAF-Mutant Melanoma: The DREAMseq Trial-ECOG-ACRIN EA6134

PURPOSE

Combination programmed cell death protein 1/cytotoxic T-cell lymphocyte-4-blockade and dual BRAF/MEK inhibition have each shown significant clinical benefit in patients with BRAFV600-mutant metastatic melanoma, leading to broad regulatory approval. Little prospective data exist to guide the choice of either initial therapy or treatment sequence in this population. This study was conducted to determine which initial treatment or treatment sequence produced the best efficacy.

PATIENTS AND METHODS

In a phase III trial, patients with treatment-naive BRAFV600-mutant metastatic melanoma were randomly assigned to receive either combination nivolumab/ipilimumab (arm A) or dabrafenib/trametinib (arm B) in step 1, and at disease progression were enrolled in step 2 to receive the alternate therapy, dabrafenib/trametinib (arm C) or nivolumab/ipilimumab (arm D). The primary end point was 2-year overall survival (OS). Secondary end points were 3-year OS, objective response rate, response duration, progression-free survival, crossover feasibility, and safety.

RESULTS

A total of 265 patients were enrolled, with 73 going onto step 2 (27 in arm C and 46 in arm D). The study was stopped early by the independent Data Safety Monitoring Committee because of a clinically significant end point being achieved. The 2-year OS for those starting on arm A was 71.8% (95% CI, 62.5 to 79.1) and arm B 51.5% (95% CI, 41.7 to 60.4; log-rank P = .010). Step 1 progression-free survival favored arm A (P = .054). Objective response rates were arm A: 46.0%; arm B: 43.0%; arm C: 47.8%; and arm D: 29.6%. Median duration of response was not reached for arm A and 12.7 months for arm B (P < .001). Crossover occurred in 52% of patients with documented disease progression. Grade ≥ 3 toxicities occurred with similar frequency between arms, and regimen toxicity profiles were as anticipated.

CONCLUSION

Combination nivolumab/ipilimumab followed by BRAF and MEK inhibitor therapy, if necessary, should be the preferred treatment sequence for a large majority of patients.

Preclinical and Clinical Trial Results Using Talazoparib and Low-Dose Chemotherapy

PURPOSE

On the basis of preclinical data, we hypothesized that low doses of chemotherapy (10% of therapeutic doses) with full dose of a PARP inhibitor could have improved efficacy and tolerability.

PATIENTS AND METHODS

In this phase I dose-escalation study, patients with BRCA-normal advanced malignancies were assigned to either talazoparib/temozolomide or talazoparib/irinotecan. Talazoparib was dose-escalated from 500 mcg to 1 mg daily before dose escalation of temozolomide/irinotecan. The starting dose of temozolomide was 25 mg/m2/day orally on days 1 to 5 and irinotecan was 25 mg/m2/day intravenously on days 1 and 15. The primary objectives of this trial were safety and tolerability, dose-limiting toxicities (DLT), and maximum tolerated dose (MTD).

RESULTS

Of 40 patients enrolled, 18 (mean: 7 prior therapies) were enrolled in talazoparib + temozolomide and 22 in talazoparib + irinotecan. DLTs were hematologic in both arms, but all hematologic adverse events resolved with either treatment interruption and/or dose reductions of talazoparib. The MTDs were talazoparib 1 mg + temozolomide 37.5 mg/m2 and talazoparib 1 mg + irinotecan 37.5 mg/m2. There were four partial responses in the talazoparib + temozolomide arm and five in the talazoparib + irinotecan arm for a response rate of 23% (9/40). The pharmacokinetic profiles of talazoparib + temozolomide/irinotecan were similar to that of talazoparib monotherapy. Responses were seen independent of homologous recombination (HR) status and HR deficiency score.

CONCLUSIONS

These results show that talazoparib with low-dose temozolomide or irinotecan is reasonably well tolerated and demonstrates clinical activity in a wide range of cancers. Randomized trials of talazoparib with or without low-dose chemotherapy are ongoing in small cell lung cancer and ovarian cancer.

Lifelong Imaging Surveillance is Indicated for Patients with Primary Retroperitoneal Liposarcoma

BACKGROUND

Surveillance imaging of patients with retroperitoneal liposarcoma (RP-LPS) after surgical resection is based on a projected risk of locoregional and distant recurrence. The duration of surveillance is not well defined because the natural history of RP-LPS after treatment is poorly understood. This study evaluated the long-term risk of recurrence and disease-specific survival (DSS) for a cohort of patients with at least 10 years of progression-free survival (10yr-PFS) from their primary resection.

METHODS

The prospective University of California, Los Angeles (UCLA) Sarcoma Database identified RP-LPS patients with 10yr-PFS after initial resection. The patients in the 10yr-PFS cohort were subsequently evaluated for recurrence and DSS. The time intervals start at date of initial surgical resection. Cox proportional hazards models were used to determine factors associated with recurrence and DSS.

RESULTS

From 1972 to 2010, 76 patients with RP-LPS had at least 10 years of follow-up evaluation. Of these 76 patients, 39 (51%) demonstrated 10yr-PFS. The median follow-up period was 15 years (range 10-33 years). Among the 10yr-PFS patients, 49% (19/39) experienced a recurrence at least 10 years after surgery. Of those who experienced recurrence, 42% (8/19) died of disease. Neither long-term recurrence nor DSS were significantly associated with age, sex, tumor size, LPS subtype, surgical margin, or perioperative treatment with radiation or chemotherapy.

CONCLUSION

Patients who have primary RP-LPS treated with surgical resection ± multimodality therapy face a long-term risk of recurrence and disease-specific death unacknowledged by current surveillance imaging guidelines. Among the patients with 10yr-PFS, 49% experienced a recurrence, and 42% of those died of disease. These findings suggest a need for lifelong surveillance imaging for patients with RP-LPS.

A randomised phase II trial of a trivalent ganglioside vaccine targeting GM2, GD2 and GD3 combined with immunological adjuvant OPT-821 versus OPT-821 alone in metastatic sarcoma patients rendered disease-free by surgery

BACKGROUND

Recurrence after resection of metastatic sarcoma is common. The gangliosides GM2, GD2 and GD3 are strongly expressed across sarcoma subtypes. We hypothesised that generation of anti-ganglioside antibodies would control micrometastases and improve outcomes in sarcoma patients who were disease-free after metastasectomy.

METHODS

We conducted a randomised phase II trial of the immunological adjuvant OPT-821 with a KLH-conjugated ganglioside vaccine targeting GM2, GD2 and GD3, versus OPT-821 alone in patients with metastatic sarcoma following complete metastasectomy. Patients received 10 subcutaneous injections at Weeks 1, 2, 3, 8, 16, 28, 40, 52, 68 and 84 and were followed for evidence of recurrent disease. The primary end-point was relapse-free survival. Secondary end-points included overall survival and serologic response.

RESULTS

A total of 136 patients were randomised, 68 to each arm. The mean age was 51.2, 52.2% were male, 90.4% had relapsed disease, 86.8% had high-grade tumours and 14% had ≥4 metastases resected. Histologies included leiomyosarcoma (33%), spindle cell sarcoma (14%), undifferentiated pleomorphic sarcoma (13%), osteosarcoma (10%), synovial sarcoma (9%), liposarcoma (9%) and others (12%). Most adverse events were Grade ≤2 (83.8% and 70.6% in the vaccine and adjuvant arms, respectively). The most common (≥20% of patients) were injection site reaction (89.7%), fatigue (44.1%) and pyrexia (27.9%) on the vaccine arm, and injection site reaction (69.1%) on the adjuvant only arm. The 1-year relapse-free survival rate (34.5% and 34.8% in the vaccine and OPT-821 monotherapy arm, respectively) did not differ between arms (P = 0.725). One-year overall survival rates were 93.1% and 91.5% in the vaccine and OPT-821 monotherapy arm, respectively (P = 0.578). Serologic responses at week 9 were more frequent on the vaccine arm (96.5% of patients) than in the adjuvant arm (32.8%), and the difference between groups was durable.

CONCLUSIONS

A sustained serologic response to vaccination was induced with the vaccine, but no difference in recurrence-free or overall survival was observed between treatment arms.

CLINICALTRIALS

gov identifier: NCT01141491.

Selinexor in Advanced, Metastatic Dedifferentiated Liposarcoma: A Multinational, Randomized, Double-Blind, Placebo-Controlled Trial

PURPOSE

Antitumor activity in preclinical models and a phase I study of patients with dedifferentiated liposarcoma (DD-LPS) was observed with selinexor. We evaluated the clinical benefit of selinexor in patients with previously treated DD-LPS whose sarcoma progressed on approved agents.

METHODS

SEAL was a phase II-III, multicenter, randomized, double-blind, placebo-controlled study. Patients age 12 years or older with advanced DD-LPS who had received two-five lines of therapy were randomly assigned (2:1) to selinexor (60 mg) or placebo twice weekly in 6-week cycles (crossover permitted). The primary end point was progression-free survival (PFS). Patients who received at least one dose of study treatment were included for safety analysis (ClinicalTrials.gov identifier: NCT02606461).

RESULTS

Two hundred eighty-five patients were enrolled (selinexor, n = 188; placebo, n = 97). PFS was significantly longer with selinexor versus placebo: hazard ratio (HR) 0.70 (95% CI, 0.52 to 0.95; one-sided P = .011; medians 2.8 v 2.1 months), as was time to next treatment: HR 0.50 (95% CI, 0.37 to 0.66; one-sided P < .0001; medians 5.8 v 3.2 months). With crossover, no difference was observed in overall survival. The most common treatment-emergent adverse events of any grade versus grade 3 or 4 with selinexor were nausea (151 [80.7%] v 11 [5.9]), decreased appetite (113 [60.4%] v 14 [7.5%]), and fatigue (96 [51.3%] v 12 [6.4%]). Four (2.1%) and three (3.1%) patients died in the selinexor and placebo arms, respectively. Exploratory RNA sequencing analysis identified that the absence of CALB1 expression was associated with longer PFS with selinexor compared with placebo (median 6.9 v 2.2 months; HR, 0.19; P = .001).

CONCLUSION

Patients with advanced, refractory DD-LPS showed improved PFS and time to next treatment with selinexor compared with placebo. Supportive care and dose reductions mitigated side effects of selinexor. Prospective validation of CALB1 expression as a predictive biomarker for selinexor in DD-LPS is warranted.

Abstract CT013: S1616: Ipilimumab plus nivolumab versus ipilimumab alone in patients with metastatic or unresectable melanoma that did not respond to anti-PD-1 therapy

Background: Patients with advanced melanoma primarily refractory to single agent PD-1 blockade therapy have an option of receiving the CTLA-4 blocking antibody ipilimumab, but if ipilimumab should be given as a single agent or in combination with the anti-PD-1 nivolumab has not been established prospectively.

Methods: Patients aged &gt;18 with metastatic or unresectable melanoma without objective response to anti-PD-1 therapy given without CTLA-4 therapy were randomized 3:1 to receive either ipilimumab 3mg/kg + nivolumab 1mg/kg q3 wks x4 cycles followed by nivolumab 480mg q4wks (ipi/nivo) up to 2 years, or ipilimumab 3mg/kg q3weeks x4 cycles (ipi). Additional key eligibility criteria included ECOG Performance Statue (PS) 0-2, no active central nervous system metastases, autoimmune disease, or need for steroids at doses of &gt;10 mg of prednisone or the equivalent. The primary endpoint was progression free survival (PFS). Disease assessments were performed every 12 weeks until progression. Secondary endpoints included overall survival (OS), objective response rate (ORR), and toxicity. All patients were to submit a fresh tumor biopsy and whole blood for correlative endpoints prior to cycle 1 and again at week 5.

Results: 92 eligible patients were enrolled, 69 to ipi/nivo, 23 to ipi. Median age was 64 and 69 in the ipi/nivo and ipi arm respectively. 67% and 65% were male. 65% of patients in both arms had ECOG PS of 0. With a median follow up of 25.3 months, the hazard ratio (HR) for PFS was 0.63 (90% CI 0.41, 0.97) with a statistically significant 1-sided p-value of 0.04 favoring ipi/nivo. The 6-month PFS estimates were 34% (90% CI: 25%-44%) and 13% (4%-27%) for ipi/nivo and ipi respectively. ORR was 28% for ipi/nivo (95% CI 17%-40%) and 9% for ipi (95% CI: 3%-34%). With a median follow up of 24.4 months, 39/69 patients in the ipi/nivo arm and 12/23 patients in the ipi arm had died. 12-month OS was 63% (90% CI 52%-72%) in the ipi/nivo arm and 57% (38%-71%) months in the ipi arm. HR for OS was 0.94 (90% CI 0.54, 1.62) in favor of ipi/nivo with a p-value of 0.42. Adverse event rates were similar in both arms. One treatment related death was reported in the ipi/nivo arm due to disseminated intravascular coagulation and one treatment related death was reported in the ipi arm due to colonic perforation.

Conclusions: This is the first prospective randomized study comparing ipi/nivo to ipi alone in patients with melanoma without response to anti-PD1 therapy. Ipi/nivo was associated with improved progression free survival as compared to ipi alone. The response rate of 28% to ipi/nivo as compared to 9% to ipi alone implies that patients who do not respond to PD-1 alone can be rescued with ipi/nivo. The toxicity of combination therapy was manageable. Ipi/nivo is an appropriate standard in patients with metastatic melanoma who do not respond to single-agent PD-1 therapy. ClinicalTrials.gov Identifier: NCT03033576

Funding: NIH/NCI grants: U10CA180888, U10CA180819, U10CA180821, U10CA180868; Other grants: SU2C-AACR-CT06-17

Citation Format: Ari M. Vanderwalde, James Moon, Kari Kendra, Nikhil I. Khushalani, Frances Collichio, Jeffrey A. Sosman, Alexandra Ikeguchi, Adrienne I. Victor, Thach-Giao Truong, Bartosz Chmielowski, David C. Portnoy, Michael C. Wu, Kenneth F. Grossmann, Antoni Ribas. S1616: Ipilimumab plus nivolumab versus ipilimumab alone in patients with metastatic or unresectable melanoma that did not respond to anti-PD-1 therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr CT013.

Updated results from the skin cancer cohorts from an ongoing phase 1/2 multicohort study of RP1, an enhanced potency oncolytic HSV, combined with nivolumab (IGNYTE)

9553

Background: RP1 is an enhanced potency oncolytic version of HSV1 that expresses human GM-CSF and the fusogenic protein GALV-GP R-. IGNYTE is a multicohort phase 1/2 study that evaluates the safety and efficacy of RP1 in combination with nivo (NCT03767348) in a range of tumor types. Preliminary data demonstrated a durable anti-tumor activity and tolerability for RP1+nivo. Here, we present updated results from the initial and melanoma (mel) and anti-PD1 naïve non-melanoma skin cancer (NMSC) cohorts with RP1+nivo. Methods: RP1 is administered via intratumoral injection Q2W, up to 10 mL/visit, first alone at a dose of 106 PFU/mL and then starting with the 2nd dose at 107 PFU/mL in combination with nivo (240 mg IV Q2W for 4 months (mos) then 480 mg IV Q4W up to 2 yrs) for up to 8 doses, with the option to re-initiate RP-1. Eligible patients (pts) must have at least one measurable & injectable tumor of ≥ 1 cm, ECOG 0-1, and no prior oncolytic therapy. For mel, both anti-PD1 naïve and failed pts were eligible, for NMSC pts who were anti-PD1 naïve. Results: As of data extraction on January 31, 2022, 13/36 pts with mel (36.1%) and 19/31 pts with NMSC (61.3%) had a best response of PR or CR. For mel this was 5/8 (62.5%), 6/16 (37.5%), 0/6 and 2/6 (33.3%) for pts with anti-PD1 naïve cutaneous, anti-PD1/anti-PD1+anti-CTLA-4 failed cutaneous, uveal and mucosal mel respectively. For the anti-PD1 naïve NMSC this included 11/17 (64.7%), 1/4 (25%), 3/4 (75%) and 4/6 (66.6%) patients with CSCC, BCC, MCC and angiosarcoma respectively, including 8/17 (47.1%) being CR for CSCC. Current immature median DOR was 13.27 mos (current range 3.67-16.93 mos) for mel, and 7.32 mos (current range 1.88-23.11mos) for anti-PD1 naïve NMSC. Any grade TEAE ( > 25%) in all cohorts combined were fatigue, nausea, pyrexia, chills, diarrhoea, pruritus, and influenza-like illness. TEAE ≥grade 3 ( > 5%) were disease progression and fatigue. No deaths related to RP1 was observed, with one death related to nivo (myocarditis). Biomarker data from paired biopsies indicated robust T cell infiltration and an increase in tumor inflammation gene signature post-treatment. Clinical responses observed were independent of baseline tumor PD-L1 expression status. Conclusions: RP1 in combination with nivo provides a durable anti-tumor activity in pts with skin cancers, including anti-PD1 failed and anti-PD1/anti-CTLA-4 failed mel. The combination continued to be generally well tolerated with no new safety signals identified. Based on this data, enrollment into both a registration-directed cohort of pts who have anti-PD1 failed cutaneous mel (n = 125) and a cohort of pts with anti-PD1 failed NMSC (n = 30) is ongoing. Up-to-date data from this ongoing trial will be reported at the conference. A randomized Ph2 trial of RP1+cemiplimab vs. cemiplimab alone in anti-PD1 naïve NMSC is also underway (NCT04050436). Clinical trial information: NCT03767348.

Newly updated activity results of alrizomadlin (APG-115), a novel MDM2/p53 inhibitor, plus pembrolizumab: Phase 2 study in adults and children with various solid tumors

9517

Background: Alrizomadlin restores TP53 function, activating p53-mediated apoptosis in tumor cells with wild-type TP53 and/or MDM2 amplification. Alrizomadlin also functions as a host immunomodulator and may restore antitumor activity in pts with cancers that progressed on PD-1/PD-L1 inhibitors. Methods: This US/Australian multicenter trial evaluated alrizomadlin, an investigational MDM2-selective, small-molecule inhibitor, combined with pembrolizumab, in pts with unresectable/metastatic melanoma that progressed on I-O drugs; pts with malignant peripheral nerve sheath tumor (MPNST), well-differentiated/dedifferentiated liposarcoma, non-small cell lung cancer (NSCLC), or solid tumors with ATM mutations that progressed on available standard therapy; or pts for whom therapy was unavailable. Eligible pts had ECOG performance status of 0-2 and, if present, stable brain metastases. Alrizomadlin 150 mg PO was administered QOD for 2 consecutive weeks, with 1 week off, and pembrolizumab 200 mg IV over 30 minutes on Day 1 of a 21-day cycle. Results: As of November 3, 2021, preliminary and interim results are reported for 130 pts in 6 cohorts: melanoma (n = 44), NSCLC (n = 26), ATM mutation (n = 18), liposarcoma (n = 17), urothelial (n = 13), and MPNST (n = 12). In the melanoma cohort, confirmed ORR by RECIST, (PR + CR) was 13% (2 CRs + 3 PRs/38 efficacy evaluable [EE] pts). In cutaneous and uveal melanoma subcohorts, confirmed ORR was 24% (2 CRs + 2 PRs/17 EE pts) and 9% (1 PR/11 EE pts), respectively. In the MPNST cohort, the clinical benefit rate, defined by confirmed ORR + SD of > 4 cycles, was 40% (4 SDs/10 EE pts). Additional confirmed PRs were reported in NSCLC, urothelial, and liposarcoma cohorts (1 each). Common treatment (alrizomadlin or pembrolizumab)-related adverse events (TRAEs; ≥ 10%) were nausea (62%), thrombocytopenia (39%), vomiting (38%), fatigue (38%), decreased appetite (29%), diarrhea (25%), neutropenia (15%), and anemia (12%). Grade 3+ TRAEs (≥ 5%) included thrombocytopenia (23%), neutropenia (10%), and anemia (7%). A total of 16 pts discontinued treatment due to AEs; 6 were treatment related, including grade 4 thrombocytopenia (n = 3), grade 2 vomiting (n = 1), grade 2 fatigue (n = 1), and grade 2 posterior reversible encephalopathy syndrome (PRES; n = 1). A total of 10 pts reported treatment-related SAEs: 1 each of abdominal pain, asthenia, colitis, febrile neutropenia, hypophysitis, peripheral edema, overdose, PRES, pulmonary embolism, pyrexia, and thrombocytopenia. Conclusions: Alrizomadlin, combined with pembrolizumab, is well tolerated and demonstrates preliminary antitumor activity in multiple tumor types and may restore antitumor effects in pts with cancer resistant or intolerant to I-O drugs. Internal study identifiers: APG-115-US-002; Keynote MK-3475-B66. Clinical trial information: NCT03611868.

Early quality of life (QOL) and symptom analysis from the DREAMseq phase III randomized control trial of combination immunotherapy versus targeted therapy in patients (pts) with BRAF-mutant metastatic melanoma (MM) (ECOG-ACRIN EA6134)

9559

Background: Combinations of either immune checkpoint inhibitors (anti-PD-1/anti-CTLA-4) or BRAF/MEK-targeted therapies have shown significant clinical benefit in pts with BRAFV600 mutant MM. Until recently, little prospective data existed to guide the choice of initial therapy or sequence. Results of the DREAMseq Trial showed that the treatment sequence beginning with nivolumab/ipilimumab (Nivo/Ipi) immunotherapy produced a clinically meaningful 20% improvement in 2-year overall survival (OS) compared to the sequence beginning with dabrafenib/trametinib (Dab/Tram) targeted therapy. The OS and progression-free survival (PFS) curves were biphasic crossing at 10 and 6 months, respectively. Our aim is to characterize QOL trends within and between the initial therapies through 24 weeks (wks). Methods: 265 pts were randomly assigned to Nivo/Ipi for up to 12 wks then Nivo alone (Arm A) or Dab/Tram continuously (Arm B) and at disease progression (PD) received the alternate therapy. QOL was assessed by the PROMIS Profile 29 at baseline, wk 12 (end of cycle (C) 2), and wk 24 (end of C4). Wilcoxon Signed Rank test was used to examine changes over time within treatment arms. OS was estimated by Kaplan-Meier method to compare between pts who stopped treatment for toxicity on Arm A by C2 and who continued on Arm A therapy to C4. A complete case analysis compared QOL domain means for (C2) vs. (C4). Pt-reported adverse events were also collected. Results: Baseline completion rates for the PROMIS-29 for Arm A (n = 108, 81.2%) and Arm B (n = 117, 88.6%) and decreased to 28.6% and 53.8%, respectively at C4. Through C4, the principal reasons for dropout were toxicity (35.2% for Arm A and 11.9% for Arm B) and PD (26.1% for Arm A and 18.6% for Arm B). From Baseline to C2: Arm B reported statistically significant improvements in Pain Interference (-3.45, P = 0.007), Sleep (-2.11, P = 0.014), and Anxiety (-3.74, P < 0.001). By C4, these early differences had dissipated (mean diff. = 0.73 – 1.73, all p = NS). For pts remaining on treatment to C4 (n = 157), a complete case analysis indicates no significant QOL differences between C2 vs C4. Pts stopping for toxicity on Arm A after C2 had similar 2-yr OS to pts who continued on Arm A to C4. QOL at C2 (Arm A: stopping for toxicity vs. on treatment) were meaningful, but underpowered (Physical Health (PH) mean difference = -3.5, p = 0.18). Conclusions: Over the first 12 wks, Dab/Tram is associated with significant improvement in overall function and less disturbance in in sleep, pain, physical function, and PH than Nivo/Ipi as expected by PFS curves and toxicity profiles. These differences dissipate by 24 wks when Arm A therapy has switched to Nivo alone and PFS curves cross. Early QOL and treatment cessation due to Nivo/Ipi toxicity was not associated with differences in 2-yr OS. Clinical trial information: NCT02224781.

DELTA-1: A global, multicenter, phase 2 study of ITIL-168, an unrestricted autologous tumor-infiltrating lymphocyte (TIL) cell therapy, in adult patients with advanced cutaneous melanoma

TPS9594

Background: Patients (pts) with advanced (unresectable or metastatic) cutaneous melanoma and persistent disease after checkpoint inhibitor therapy have poor outcomes and limited treatment options, highlighting a significant unmet medical need (Schadendorf D et al. Lancet. 2018;392:971-984). Investigational autologous TIL cell therapies have shown promise in this population, partly attributable to their intrinsic and patient-specific antitumor activity (Borch TH et al. J Immunother Cancer. 2020;8:e000668). Made from each patient’s digested and cryopreserved tumor, ITIL-168 is an autologous TIL cell therapy manufactured to offer an unrestricted T-cell receptor repertoire. A single-center, compassionate use clinical series demonstrated the feasibility and clinical utility of an earlier version of ITIL-168, with a high overall response rate among pts previously treated with PD-1 inhibitor (PD-1i) therapy (58%, n = 12; Pillai M et al. Ann Oncol. 2021;32[suppl 5]:S882). DELTA-1 (NCT05050006) is a global, multicenter phase 2 study to evaluate efficacy and safety of ITIL-168 in pts with cutaneous melanoma relapsed or refractory to a PD-1i, pts intolerant to a PD-1i, and pts whose current best response to a PD-1i is stable disease. Methods: Pts aged ≥18 years with histologically confirmed advanced cutaneous melanoma, ECOG performance status 0-1, and adequate organ function will be enrolled in 1 of 3 cohorts. Cohort 1 (n≈80) will include pts who relapsed after or were refractory to ≥1 prior line of systemic therapy, including a PD-1i and, if BRAF-mutated, a BRAFi ± MEKi. Cohorts 2 and 3 (n≈25 each) will include pts intolerant to PD-1i and those with stable disease after ≥4 doses of PD-1i, respectively. After tumor resection for TIL harvest, pts must have ≥1 remaining measurable lesion per RECIST 1.1. Pts with uveal, acral, or mucosal melanoma, prior allogeneic transplant or cell therapy, and with central nervous system (CNS) disorder or symptomatic and/or untreated CNS metastases are ineligible. Pts will receive 5 days of lymphodepleting chemotherapy (cyclophosphamide ×2 days overlapping with fludarabine ×5 days) followed by a single ITIL-168 infusion (≥5×109 cells) and supportive short-course, high-dose IL-2. The primary endpoint is objective response rate (ORR) per central review. Secondary endpoints include duration of response, progression-free survival, overall survival, disease control rate, TIL persistence, and safety. Hypothesis testing of ORR will be performed for cohort 1. The primary analysis will occur when all pts in the cohort 1 modified intent-to-treat population have been followed for ≥6 months after the first posttreatment disease assessment. DELTA-1 opened for enrollment in September 2021. Updated site information will be given at the time of presentation. Clinical trial information: NCT05050006.

Neoadjuvant PD-1 blockade in patients with resectable desmoplastic melanoma (SWOG 1512)

9502

Background: Desmoplastic melanoma (DM) is a rare cancer defined by a dense fibrous collagen matrix. It is associated with high UV exposure leading to a high mutational load. When locally advanced, the standard of care is wide excision and radiation therapy due to its propensity for local relapses. Metastatic DM has a high response rate (RR) to PD-1 blockade therapy (Eroglu et al. Nature 2018). We hypothesized that neoadjuvant treatment with anti-PD-1 monotherapy may induce pathologically confirmed regressions in a high percentage of cases, potentially allowing for less extensive local treatment. Methods: Patients > 18 years old with histologically confirmed resectable (primary, recurrent, or regional lymph node metastasis) DM with clinical evidence of residual disease received pembrolizumab 200 mg q3 weeks (wk) 3 followed by excision. No adjuvant therapy was administered. Primary endpoint: pathological complete response (pCR), with the assumption that pCR of 25% would be considered a positive result worthy of future study. To test this hypothesis, a single arm trial with 25 eligible patients would have a 3.4% probability of a positive result with a true pCR of 5%, and a power of 90% of a positive result if the true pCR is 25%. Secondary endpoints: clinical RR by imaging and clinical exam, median overall survival (OS), and evaluation of safety/tolerability of neoadjuvant pembrolizumab. Adverse events were assessed q3 wk. Disease assessments occurred at baseline and q9 wk. NCT02775851. Results: We enrolled-29 eligible patients with resectable DM. One patient refused treatment and was omitted from further analysis. Median age was 75, 79% were male, primary sites of disease were 72% H&N, 10% torso, 14% extremities, 3% unknown. No patients received prior systemic therapy. Mean time from C1D1 treatment to surgery was 84.2 (range: 52-135) days, mean number of cycles received 3.3 (range: 2-4). 26/27 (93%) of patients underwent wide excision of the resectable disease, of which 14 (54%) underwent sentinel lymph node biopsy. One patient underwent resection of a nodal recurrence thus did not require wide excision. pCR was noted in 15/27 (56%) of patients (95% CI: 35%-75%). One patient without a pCR had a major pathologic response with 0.2 mm residual melanoma. In addition, one patient with a clinical CR did not undergo resection by choice. None became inoperable. Clinical RR was 52% (95% CI: 32%-71%). Median OS has not been reached, with two nontreatment related deaths (acute hypoxic respiratory failure; unknown). No > grade 2 related adverse events were observed. Conclusions: Neoadjuvant pembrolizumab in resectable DM results in a high pCR rate with excellent tolerance, which supports consideration of PD-1 blockade therapy prior to surgery. Funding: U10CA180888 and U10CA180819; and in part by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Clinical trial information: NCT02775851.

Retrospective analysis of adjuvant treatment for localized, operable uterine leiomyosarcoma

OBJECTIVE

Currently, there is no standard adjuvant treatment protocol for localized uterine leiomyosarcoma (uLMS) as clinical trials to address this question have been retrospective, underpowered, or undermined by slow accrual rates. The aim of this study is to determine the benefit of adjuvant chemotherapy for uLMS.

METHODS

We reviewed the medical records of localized uLMS patients who had underwent adjuvant therapy after upfront surgery between 2000 and 2020. The cases were blinded for review. We evaluated the influence of various clinical characteristics and different types of adjuvant therapies on specific outcomes.

RESULTS

Sixty-eight patients (median age: 50 years) were included for analysis. Forty of 68 (58.8%) patients received adjuvant chemotherapy +/- radiation therapy and 25 patients (38.6%) did not receive any adjuvant therapy. At a median follow-up time of 43.3 months, 45 patients (66.1%) had relapsed disease. The median disease-free survival (mDFS) for all patients was 23.1 months. Patients who received any adjuvant treatment (chemotherapy and/or radiation) trended toward a longer mDFS compared with those who did not receive any adjuvant therapy (29.7 vs. 14.1 months, p = 0.26). Patients who received adjuvant chemotherapy alone had a longer, but nonstatistically significant mDFS compared with those who did not receive any adjuvant treatment (22.2 vs. 14.1 months, p = 0.18). Additionally, univariate analysis found that tumor size large than 10 cm, and a mitotic rate >10/10hpf were independent prognostic factors for worse DFS.

CONCLUSIONS

Though DFS was more favorable among those who received adjuvant therapy, it was not statistically significant, and thus based on this data adjuvant therapy for resected uLMS is still in question.

Adjuvant Pembrolizumab versus IFNα2b or Ipilimumab in Resected High-Risk Melanoma

We conducted a randomized phase III trial to evaluate whether adjuvant pembrolizumab for one year (647 patients) improved recurrence-free survival (RFS) or overall survival (OS) in comparison with high-dose IFNα-2b for one year or ipilimumab for up to three years (654 patients), the approved standard-of-care adjuvant immunotherapies at the time of enrollment for patients with high-risk resected melanoma. At a median follow-up of 47.5 months, pembrolizumab was associated with significantly longer RFS than prior standard-of-care adjuvant immunotherapies [HR, 0.77; 99.62% confidence interval (CI), 0.59-0.99; P = 0.002]. There was no statistically significant association with OS among all patients (HR, 0.82; 96.3% CI, 0.61-1.09; P = 0.15). Proportions of treatment-related adverse events of grades 3 to 5 were 19.5% with pembrolizumab, 71.2% with IFNα-2b, and 49.2% with ipilimumab. Therefore, adjuvant pembrolizumab significantly improved RFS but not OS compared with the prior standard-of-care immunotherapies for patients with high-risk resected melanoma.

SIGNIFICANCE

Adjuvant PD-1 blockade therapy decreases the rates of recurrence, but not survival, in patients with surgically resectable melanoma, substituting the prior standard-of-care immunotherapies for this cancer. See related commentary by Smithy and Shoushtari, p. 599. This article is highlighted in the In This Issue feature, p. 587.

CSF1 receptor inhibition of tenosynovial giant cell tumor using novel disease-specific MRI measures of tumor burden

Aim: Monitoring treatment of tenosynovial giant cell tumor (TGCT) is complicated by the irregular shape and asymmetrical growth of the tumor. We compared responses to pexidartinib by Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 with those by tumor volume score (TVS) and modified RECIST (m-RECIST). Materials & methods: MRIs acquired every two cycles were assessed centrally using RECIST 1.1, m-RECIST and TVS and tissue damage score (TDS). Results: Thirty-one evaluable TGCT patients were treated with pexidartinib. From baseline to last visit, 94% of patients (29/31) showed a decrease in tumor size (median change: -60% [RECIST], -66% [m-RECIST], -79% [TVS]). All methods showed 100% disease control rate. For TDS, improvements were seen in bone erosion (32%), bone marrow edema (58%) and knee effusion (46%). Conclusion: TVS and m-RECIST offer potentially superior alternatives to conventional RECIST for monitoring disease progression and treatment response in TGCT. TDS adds important information about joint damage associated with TGCT.

Results from Phase I Extension Study Assessing Pexidartinib Treatment in Six Cohorts with Solid Tumors including TGCT, and Abnormal CSF1 Transcripts in TGCT

PURPOSE

To assess the response to pexidartinib treatment in six cohorts of adult patients with advanced, incurable solid tumors associated with colony-stimulating factor 1 receptor (CSF1R) and/or KIT proto-oncogene receptor tyrosine kinase activity.

PATIENTS AND METHODS

From this two-part phase I, multicenter study, pexidartinib, a small-molecule tyrosine kinase inhibitor that targets CSF1R, KIT, and FMS-like tyrosine kinase 3 (FLT3), was evaluated in six adult patient cohorts (part 2, extension) with advanced solid tumors associated with dysregulated CSF1R. Adverse events, pharmacokinetics, and tumor responses were assessed for all patients; patients with tenosynovial giant cell tumor (TGCT) were also evaluated for tumor volume score (TVS) and patient-reported outcomes (PRO). CSF1 transcripts and gene expression were explored in TGCT biopsies.

RESULTS

Ninety-one patients were treated: TGCT patients (n = 39) had a median treatment duration of 511 days, while other solid tumor patients (n = 52) had a median treatment duration of 56 days. TGCT patients had response rates of 62% (RECIST 1.1) and 56% (TVS) for the full analysis set. PRO assessments for pain showed improvement in patient symptoms, and 76% (19/25) of TGCT tissue biopsy specimens showed evidence of abnormal CSF1 transcripts. Pexidartinib treatment of TGCT resulted in tumor regression and symptomatic benefit in most patients. Pexidartinib toxicity was manageable over the entire study.

CONCLUSIONS

These results offer insight into outcome patterns in cancers whose biology suggests use of a CSF1R inhibitor. Pexidartinib results in tumor regression in TGCT patients, providing prolonged control with an acceptable safety profile.

DREAMseq (Doublet, Randomized Evaluation in Advanced Melanoma Sequencing): A phase III trial—ECOG-ACRIN EA6134

356154

Background: Combinations of immune checkpoint inhibitors (CPI) blocking PD-1 and CTLA-4 or BRAF/MEK inhibitors have both shown significant antitumor efficacy and overall survival (OS) benefit in patients (pts) with BRAFV600-mutant metastatic melanoma (MM), leading to broad regulatory approval. Little prospective data exists to guide the choice of one over the other as initial therapy or the preferred treatment sequence in this population. The DREAMseq Trial was designed to compare the efficacy and toxicity of the sequence of nivolumab/ipilimumab (N/I) followed by dabrafenib/trametinib (D/T) to the converse sequence. Methods: Eligible pts with treatment-naive BRAFV600-mutant MM were stratified by ECOG Performance Status (PS) 0 or 1 and LDH level and randomized 1:1 to receive Step 1 with either N/I (Arm A) or D/T (Arm B) and at disease progression (PD) were enrolled in Step 2 receiving the alternate therapy, D/T (Arm C) or N/I (Arm D), respectively. Pts received N (1mg/kg)/I (3 mg/kg) q3 wks x 4 doses followed by N 240 IV q2 wks for up to 72 wks (Arms A and D) or D 150 mg po BID and T 2 mg po qD until PD (Arms B and C). In 2019, investigators were given the option to use alternate induction dosing of N (3mg/kg)/I (1 mg/kg) q3 wks x 4 doses for Arms A and D. Cycles were every 6 wks and imaging was obtained at baseline and q12 wks on each arm. Primary endpoint was 2-year OS. At the 4th Interim Analysis with 59% of pts being 2 yrs from enrollment, the DSMC and NCI CTEP recommended halting accrual and releasing the data. Results: Beginning 7/2015, 265 out of a proposed 300 pts were enrolled (133 Arm A and 132 Arm B). Median age was 61 (25-85) and 63% were male. Demographics for Arm A and B were balanced with 67% PS 0 and 60% with normal LDH. As of 7/16/21, at a median follow-up of 27.7 mos, 27 pts had switched to Arm C and 46 to Arm D. Overall Grade 3+ toxicity was 60% in Arm A and 52% in Arm B. Grade 5 treatment-related AEs included 2 on Arm A and 1 on Arm C. ORR to date is: Arm A 46% (52/113), Arm B 43% (49/114), Arm C 48% (11/23) and Arm D 30% (8/27). 37/42 assessed pts in Arm A and 19/37 in Arm B remain in response. Median DOR: Arm A- Not reached; Arm B-12.7 mos (95% CI: 8.2, -) (p <0.001). There were 100 deaths (Arm A to C- 38/Arm B to D- 62). 2-yr OS rate for those starting with Arm A was 72% (95% CI: 62-81%) and for Arm B 52% (95% CI: 42-62%) (log-rank p= 0.0095). PFS showed a trend in favor of Arm A (log-rank p=0.054). Both the PFS and OS curves show a biphasic pattern with Arm B being above Arm A until 6 and 10 mos, respectively. For the 115 pts with documented progression on Step 1 (Arm A-44/Arm B-71), 60 (52%) had registered for Step 2. The principal reason for not enrolling on Step 2 was death from PD within 6 mos (Arm A:15/23; Arm B: 25/32). Conclusions: For pts with advanced BRAFV600-mutant MM, the treatment sequence beginning with the CPI combination of N/I resulted in superior OS, which became evident at 10 mos, with longer Step 1 DOR and more ongoing responses than the treatment sequence beginning with D/T. Clinical trial information: NCT02224781.

950 Final analysis: phase 1b study investigating intratumoral injection of toll-like receptor 9 agonist vidutolimod ± pembrolizumab in patients with PD-1 blockade–refractory melanoma

Background

There are limited therapeutic options for patients with progressive disease (PD) on or after PD-1–blocking antibody therapy. Vidutolimod (CMP-001) is a first-in-class, immunostimulatory virus-like particle containing a CpG-A Toll-like receptor 9 (TLR9) agonist. This phase 1b study evaluated the safety and clinical activity of intratumoral vidutolimod with and without pembrolizumab in patients with refractory melanoma.

Methods

This two-part, open-label, multicenter, phase 1b study (NCT02680184) enrolled adults with histologically confirmed metastatic or unresectable cutaneous melanoma who had stable disease after ≥12 weeks or PD on anti−PD-1 treatment, measurable disease per RECIST v1.1, ECOG PS 0/1, and ≥1 lesion accessible for intratumoral injection. Part 1 evaluated vidutolimod + pembrolizumab and Part 2 evaluated vidutolimod monotherapy. Key objectives included assessment of safety and clinical activity, and exploratory analyses were performed on available tumor biopsies using immunohistochemistry and RNAseq.

Results

At data cutoff (August 17, 2021), 159 patients had enrolled in Part 1 and 40 patients in Part 2. The median age was 64 years in Part 1 (range, 30-90) and 68 years in Part 2 (range, 30-89). Most patients had PD as their last response to prior anti–PD-1 therapy (Part 1, 93.1%; Part 2, 80.0%). Grade 3/4 treatment-related adverse events (TRAEs) occurred in 37.1% of patients treated with vidutolimod + pembrolizumab and in 22.5% of patients treated with vidutolimod monotherapy. No treatment-related deaths occurred. Based on the efficacy data presented in Table 1, vidutolimod polysorbate 20 (PS20) A was selected for further development as this formulation in combination with pembrolizumab had a best objective response rate (ORR; RECIST v1.1) of 23.5%, with a median duration of response (DOR) of 25.2 months. Vidutolimod monotherapy had an ORR of 20.0%, with a median DOR of 5.6 months. Exploratory translational analyses identified association of unique biomarkers with response among patients with T cell–inflamed versus non-T cell–inflamed tumors at baseline.

Abstract 950 Table 1

Safety and clinical activity of vidutolomod ± pembrolizumab

Conclusions

Promising clinical activity was observed with vidutolimod + pembrolizumab and vidutolimod monotherapy in patients with PD-1 blockade–refractory melanoma. A manageable safety profile was observed. The DOR with vidutolimod + pembrolizumab was substantially longer than with vidutolimod monotherapy. Clinical studies to confirm the efficacy of vidutolimod + PD-1 blockade in patients with previously untreated unresectable/metastatic melanoma (phase 2/3, NCT04695977) or PD-1 blockade–refractory melanoma (phase 2, NCT04698187) are ongoing.

Acknowledgements

This work was supported by Checkmate Pharmaceuticals. Medical writing assistance was provided by Steffen Biechele, PhD (ApotheCom, San Francisco, CA, USA), and funded by Checkmate Pharmaceuticals.

Trial Registration

NCT02680184

Ethics Approval

This study was approved by the WCG-WIRB; WIRB approval tracking number: 20152597.

506 IGNYTE: an open-label, multicenter, phase 1/2 (Ph 1/2) clinical trial of RP1 ± nivolumab in patients with advanced solid tumors

Background

RP1 is an enhanced potency oncolytic HSV-1 which expresses a fusogenic glycoprotein (GALV-GP R-) and granulocyte macrophage colony stimulating factor (GM-CSF).1 In pre-clinical studies, RP1 demonstrated potent GALV-GP R-enhanced anti-tumor activity and immunogenic cell death. This Phase 1/2 (Ph 1/2) study was designed to evaluate the safety and efficacy of RP1 ± nivolumab (nivo) in patients (pts) with advanced solid tumors, including pts whose disease failed prior anti-PD-1/PD-L1 therapy and has reported promising interim data in a number of tumor types including cutaneous squamous cell carcinoma (CSCC) and anti-PD1 failed melanoma to date.2

Methods

This is a multi-center, first-in-human, open label, multi-cohort, non-randomized Ph1 study of RP1 alone and combined with nivo followed by Ph2 in combination with nivo in pts with recurrent advanced solid tumors including those that progressed after prior anti-PD-1/PD-L1 therapy. The Ph 1 monotherapy dose escalation (n=14) and RP-1 combination expansion (n=22) cohorts are fully enrolled. Approximately 260 pts are expected to be enrolled in the ongoing Ph 2 portion across five cohorts; melanoma (n=30, enrollment complete), non-melanoma skin cancer (n=45, to include 15 pts with anti-PD-1/PD-L1 failed disease), anti-PD-1 failed MSI-H/dMMR tumors (n=30), anti-PD-1/PD-L1-failed non-small-cell lung cancer (n=30) and a registration-directed cohort in anti-PD-1 failed cutaneous melanoma (n=125). Pts in the Ph 2 portion receive up to 10 mL of RP1 intratumorally into one or more superficial or deep seated/visceral lesions at the recommended Ph 2 dose (1x10^6 PFU/mL × 1 followed by 1x10^7 PFU/mL × 7, Q2W). Following the first dose of RP1, nivo (240 mg IV Q2W for 4 months then 480 mg IV Q4W for up to 2 years) is subsequently administered in combination. Pts may receive up to 8 additional doses of RP1 if they meet protocol-specified criteria. Tumor assessments are performed Q8W. The primary objectives of the Ph 2 part of the study are to assess the safety, tolerability, and overall response rate (ORR) of RP1 in combination with nivo, by independent review for the anti-PD1 failed melanoma cohort. Secondary objectives include duration of response, complete response rate, disease control rate, PFS, 1-year and 2-year survival rates. Exploratory objectives include biodistribution and shedding analysis of RP1 and biomarker studies, including analyses of tumor biopsies and blood samples. Enrollment is currently ongoing in the UK and US, with additional sites in the EU (including France and Spain) are expected to open in 2021.

Trial Registration

NCT03767348

References

Thomas S, Kuncheria L, Roulstone V, Kyula JN, Mansfield D, Bommareddy PK, Smith H, Kaufman HL, Harrington KJ, Coffin RS. Development of a new fusion-enhanced oncolytic immunotherapy platform based on herpes simplex virus type 1. J Immunother Cancer 2019;7(1):214.

Coffin R, Astley-Sparke P, and Middleton M (2021, June 3rd). Retrieved from https://ir.replimune.com/static-files/f4fe3349-e082-4d41-94a1-106ce7e78a23

Ethics Approval

The study was approved by institutional review board or the local ethics committee at each site. Informed consent was obtained from patients prior to enrollment.

523 Preliminary clinical experience with XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors

Background

XmAb20717 is a humanized bispecific monoclonal antibody that simultaneously targets PD-1 and CTLA-4. We report updated data on patients treated at the recommended expansion dose from an ongoing, multicenter, Phase 1, dose-escalation and -expansion study of intravenous XmAb20717 in patients with selected advanced solid tumors that progressed after treatment with all standard therapies or with no standard therapeutic options.

Methods

A maximum tolerated dose was not reached in dose escalation. XmAb20717 10 mg/kg every 2 weeks (Q2W) was selected as the expansion dose, based on consistent T-cell proliferation in peripheral blood indicative of dual PD-1/CTLA-4 checkpoint blockade, and response to treatment (RECIST[1.1]).1 Parallel expansion cohorts included ~20 patients each with melanoma, renal cell carcinoma (RCC), non-small cell lung cancer (NSCLC), castration-resistant prostate cancer (CRPC), and a basket of tumor types without an FDA-approved checkpoint inhibitor (CI). Patients treated with 10 mg/kg in dose escalation were pooled with expansion cohorts for analysis of clinical activity and safety.

Results

As of 9 June 2021, 110 patients, ranging in age from 39 to 89 years and 66.4% male, were treated, and 5 were continuing treatment. Patients had received a median of 4 prior systemic treatment regimens, including CI therapy for 64.5%. The objective response rate was 13.0% (10/77 patients evaluable for efficacy), including 1 complete response (melanoma [confirmed]) and 9 partial responses (confirmed: 1 melanoma, 2 RCC, 2 CRPC, 1 ovarian cancer; unconfirmed: 1 melanoma, 2 NSCLC). The CRPC responders (2/7 with RECIST-measurable disease) had confirmed PSA decreases ≥ 50% from baseline (to 0.02 and 0.3 ng/mL); neither had progression on bone scans. All responders had prior CI exposure, except those with CRPC. Robust CD4 and CD8 T-cell activation was seen. Low baseline tumoral expression of myeloid recruitment genes, including IL-8, was associated with clinical benefit. Grade ≥ 3 immunotherapy-related adverse events in ≥ 3 patients included rash (16.4%), transaminase elevations (9.1%), hyperglycemia (4.5%), acute kidney injury (3.6%), amylase and lipase increased (2.7%), and lipase increased (2.7%).

Conclusions

Preliminary data indicate 10 mg/kg XmAb20717 Q2W was associated with complete and partial responses in multiple tumor types and was generally well-tolerated in these heavily pretreated patients with advanced cancer. Changes in T-cell populations in the periphery and tumor are consistent with robust dual checkpoint blockade. These findings support further development of XmAb20717 in advanced solid tumors, including metastatic prostate cancer.

Trial Registration

NCT03517488

References

Shum E, Daud A, Reilley M, et al. Preliminary safety, pharmacokinetics/pharmacodynamics, and antitumor activity of XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors. JITC 2020;8(3):A247-8.

Ethics Approval

The study was approved by each institution’s IRB.

544 DELTA-1: A global, multicenter phase 2 study of ITIL-168, an unrestricted autologous tumor-infiltrating lymphocyte (TIL) cell therapy, in adult patients with advanced cutaneous melanoma

Background

Patients with advanced cutaneous melanoma and persistent disease after checkpoint inhibitor therapy have poor outcomes and limited treatment options, highlighting a significant unmet medical need.1 Autologous TIL cell therapies have shown promise in this population attributable, in part, to their intrinsic and patient-specific antitumor activity2; however, no such therapies are approved. Made from each patient‘s digested and cryopreserved tumor, ITIL-168 is an autologous TIL cell therapy manufactured to offer an unrestricted T-cell receptor repertoire. A single-center compassionate use clinical series demonstrated the feasibility and clinical utility of an earlier version of ITIL-168.3 DELTA-1 is a global, multicenter phase 2 study to evaluate efficacy and safety of ITIL-168. DELTA-1 will enroll patients with melanoma relapsed after or refractory to PD-1 inhibitors (PD-1i), patients intolerant to PD-1i, and patients whose best response to PD-1i was stable disease.

Methods

Patients aged ≥18 years with histologically confirmed advanced cutaneous melanoma, ECOG performance status 0–1, and adequate organ function will be enrolled in 1 of 3 cohorts. Cohort 1 (n≈80) will include patients who relapsed after or were refractory to ≥1 prior line of systemic therapy, including a PD-1i and, if BRAF-mutated, a BRAFi ± MEKi. Cohorts 2 and 3 (n≈25 each) will include patients intolerant to PD-1i and those with stable disease after ≥4 doses of PD-1i, respectively. After tumor resection for TIL harvest, patients must have ≥1 remaining measurable lesion per Response Evaluation Criteria in Solid Tumors (RECIST) 1.1. Patients with uveal, acral, or mucosal melanoma, prior allogeneic transplant or cell therapy, and with central nervous system (CNS) disorder or symptomatic and/or untreated CNS metastases are ineligible. Patients will receive 5 days of lymphodepleting chemotherapy (cyclophosphamide ×2 days overlapping with fludarabine ×5 days) followed by a single ITIL-168 infusion (≥5×109 cells) and supportive short course high-dose IL-2. The primary endpoint is objective response rate (ORR) per central review. Key secondary endpoints include duration of response, progression-free survival, overall survival, disease control rate, TIL persistence, and safety. Hypothesis testing of ORR will be performed for cohort 1. Two interim analyses will occur after 20 patients in cohort 1 have been followed for ≥28 days (safety) and evaluated for response ≥3 months after ITIL-168 infusion (futility). The primary analysis will occur when all patients in the cohort 1 modified intent-to-treat population have been followed for ≥6 months after the first posttreatment disease assessment.

Acknowledgements

Medical writing support was provided by Christopher Waldapfel, PharmD, of Instil Bio, Inc, and Phylicia Aaron, PhD, of Nexus GG Science, with funding from Instil Bio, Inc.

References

Schadendorf D, van Akkoi ACJ, Berking C, et al. Melanoma. Lancet 2018;392(10151):971–984.

Borch TH, Anderson R, Ellebaek E, et al. Future role for adoptive T-cell therapy in checkpoint inhibitor-resistant metastatic melanoma. J Immunother Cancer 2020;8(2):e000668.

Hawkins RE, Jiang Y, Lorigan PC, et al. Clinical feasibility and treatment outcomes with unselected autologous tumor infiltrating lymphocyte therapy in patients with advanced cutaneous melanoma. Cancer Res 2021;81(13):LB150.

Ethics Approval

All patients will provide written informed consent. The study will be approved by the Institutional Review Board/Independent Ethics Committee at each site and conducted in accordance with the Good Clinical Practice Guidelines of the International Conference on Harmonisation.

Consent

N/A; the abstract does not contain sensitive or identifiable patient information.

A Randomized Phase 2 Study Of Nivolumab Monotherapy Or Nivolumab Combined with Ipilimumab In Patients with Advanced Gastrointestinal Stromal Tumors

PURPOSE

Most GISTs are driven by KIT/PDGFRa mutations. TKI benefit is progressively less after imatinib failure. This phase II trial analyzed the efficacy of nivolumab (N) or nivolumab + ipilimumab (N + I) in refractory GIST patients.

PATIENTS AND METHODS

Advanced/metastatic GIST patients refractory to at least imatinib were randomized 1:1 in a noncomparative, parallel group, unblinded Phase 2 trial of N (240mg Q2wks) or N + I (240 mg Q2wks + 1mg/kg Q6wks). The primary endpoint was the ORR of N alone or N+I by RECIST 1.1 in the ITT population.

RESULTS

36 patients with a median of 3 (1-6) prior lines of therapies were enrolled. 10/19(52.6%) patients had SD for a CBR of 52.6 % in the N arm and the median PFS was 11.7 wks (95% CI, 7.0, 17.4). In the N+I arm, 1/16(6.7%) patients had a CR and 4/16(25.0%) had SD for a CBR of 31.3% and a median PFS of 8.3wks (95% CI, 5.6, 22.2). The 4 and 6 month PFS were 42.1% and 26.3%, respectively for N and 31.3% and 18.8%, respectively for N+I. The most common adverse events (AEs) attributed to N and N+I were fatigue: 13.9% and 22.2%, respectively. There were 9 total attributable grade 3-4 AEs.

CONCLUSIONS

The primary endpoint of RR>15% was not observed for N or N + I. In a heavily pretreated GIST population, responses and long term disease control with both N and N+I were observed. No new safety signals have been observed.

Overcoming PD-1 Blockade Resistance With CpG-A Toll-Like Receptor 9 Agonist Vidutolimod in Patients With Metastatic Melanoma

Patients with advanced melanoma that is resistant to programmed death-1 (PD-1) blockade therapy have limited treatment options. Vidutolimod (formerly CMP-001), a virus-like particle containing a CpG-A Toll-like receptor 9 (TLR9) agonist, may reverse PD-1 blockade resistance by triggering a strong interferon response to induce and attract antitumor T cells. In the dose-escalation part of this phase 1b study, vidutolimod was administered intratumorally at escalating doses with intravenous pembrolizumab to 44 patients with advanced melanoma who had progressive disease or stable disease on prior anti-PD-1 therapy. The combination of vidutolimod and pembrolizumab had a manageable safety profile and durable responses were observed in 25% of patients, with tumor regression in both injected and noninjected lesions, including visceral lesions. Patients who responded to vidutolimod and pembrolizumab had noninflamed tumors at baseline and induction of an interferon-γ gene signature following treatment, as well as increased systemic expression of the interferon-inducible chemokine CXCL10.

Abstract 331: Characterization of neoepitope (neoE)-specific T cells from peripheral blood for adoptive neoTCR-T cell therapy for patients with breast cancer (bc) or ovarian cancer (oc)

Introduction: Broad application of neoTCR-T cell therapy involves isolation of mutation-targeted CD8 T cells from the blood of patients with different tumor types. An ultra-sensitive process streamlined for high-throughput capture of neoE-specific T cells from blood is leveraged for producing a fully personalized adoptive T cell therapy for trial participants with BC or OC (NCT03970382).

Methods: Expressed mutations were identified by comparative sequencing of blood cells and tumor tissue. HLA typing was performed with OpiType. Proprietary algorithms were used to predict and prioritize tumor-exclusive neoE-HLA candidates. A library of barcoded HLA-mutational neoantigen complexes was used to interrogate PBMCs from each patient using imPACT Isolation Technology® (Dalmas et al., 2020). NeoTCRs cloned from captured antigen-experienced CD8 T cells were precision genome engineered into healthy donor T cells for functional characterization, including secretion of cytokines and effector molecules (Jacoby et al., 2019; Sennino et al., 2019). Based on pre-specified prioritization criteria, up to 3 actionable neoTCRs were selected for manufacturing the products for each individual.

Results: Six patients (2 BC/4 OC) successfully underwent neoTCR product selection. The median age was 59.5 years (range 38-69). Patients received a median of 5.5 prior regimens for metastatic disease (range 4-9). Median tumor mutational burden (TMB) was 2.7 (range 0.9-13.4). HLA-neoantigen libraries contained a median of 91 snares (range 29-262) and represented 6/6 HLA alleles in 4 patients and 5/6 in the remaining 2. A median of 8.5 distinct neoE-specific T cells (range 5-15) were isolated per patient. Following functional characterization 13 neoTCRs met selection criteria: three patients with 3 TCRs, one with 2 TCRs, and two had a single TCR. The median predicted neoE:HLA affinity of the selected TCRs was 77 nM (range 6.3 - 5866) and the median IFN-g EC50 was 4 ng/mL (range 1-431).

Conclusion: Relevant antigen-experienced, tumor mutation-targeted CD8 T cells were isolated from the blood of heavily pre-treated BC and OC patients with low TMB (&lt;10 mutations/Mb). Correlations between TCR characteristics and clinical and biomarker data are planned. This approach holds potential for broad use in women with BC or OC.

Citation Format: Mihaela Cristea, Bartosz Chmielowski, David Y. Oh, Roel P. Funke, Daniela A. Bota, Mehrdad Abedi. Characterization of neoepitope (neoE)-specific T cells from peripheral blood for adoptive neoTCR-T cell therapy for patients with breast cancer (bc) or ovarian cancer (oc) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 331.

Abstract 436: Whole body imaging of genetically labeled hematopoietic stem cells in human subjects

Background: Despite decades of experience with bone marrow transplantation, there has not been prior whole body visualization of the engraftment of hematopoietic stem cell (HSC) in bone marrow in humans. The herpes simplex virus type 1 sr39 thymidine kinase (sr39tk) gene is a positron emission tomography (PET) reporter/suicide gene that can be used to genetically label cells and track them in vivo based on the ability to retain the PET tracer [18F]FHBG, which is a penciclovir analogue.

Methods: Three patients with metastatic sarcoma were treated with gene-modified autologous CD34+ peripheral blood stem cells (PBSCs) transduced with a lentiviral vector encoding both a transgenic T-cell receptor against the tumor antigen NY-ESO-1 and the sr39tk reporter/suicide gene after a reduced intensity conditioning regimen of busulfan and fludarabine. These gene-modified stem cells were co-administered with gene-modified autologous T-cells also encoding the NY-ESO-1 T-cell receptor. The primary endpoint was safety and feasibility, while an exploratory endpoint was standardized uptake value of [18F]FHBG PET between post-transplant day +25 and day +120 scans to study the biodistribution of the gene-modified PBSCs and progeny T cells.

Results: Two patients (NYSCT-01 and NYSCT-03) demonstrated robust engraftment the gene-modified PBSCs in bone marrow niches by day +25-30, as demonstrated by whole body [18F]FHBG PET. PET signal was evident throughout the body in the bone marrow in the scalp, jaw, vertebrae, ribs, pelvis, femur and other bones with significant areas of bone marrow. The third patient (NYSCT-05), whose product had much lower transduction efficiency, did not display any engraftment signal at day +28. Patient NYSCT-01 demonstrated loss of [18F]FHBG signal at day +120, with no detectable T-cell progeny in peripheral circulation. Patient NYSCT-03 developed a post-transplant de novo multidrug-resistant cytomegalovirus (CMV) viremia at day +58 which ultimately required treatment with systemic ganciclovir, and passed away prior to her day +120 PET scan. Patient NYSCT-05 developed a post-transplant CMV reactivation viremia on day +45, which responded to oral valganciclovir treatment.

Conclusions: PET imaging allowed visualization of the successful engraftment of sr39tk reporter gene-labeled HSCs in bone marrow niches. Further studies are needed to determine mechanisms of loss of engraftment due to immunogenicity of the sr39tk gene, or insufficient transduction efficiency.

Citation Format: Theodore S. Nowicki, Beata Berent-Maoz, Cristina Puig-Saus, Paula Kaplan-Lefko, Ignacio Baselga Carretero, Ameya Champhekar, Giuseppe Carlucci, Mignonette Macabali, Ivan Perez Garcilazo, Agustin Vega-Crespo, Jonathan Rodriguez, Bartosz Chmielowski, Arun Singh, Martin Allen-Auerbach, Shaojun Zhu, Roger Slavik, Begonya Comin-Anduix, John Williams, Antoni Ribas. Whole body imaging of genetically labeled hematopoietic stem cells in human subjects [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 436.

Abstract CT221: A phase I study of intratumoral BO-112 and nivolumab for resectable soft tissue sarcoma

Background: BO-112 is a double stranded synthetic RNA formulated with polyethyleneimine. By mimicking a viral infection, it mobilizes the immune system, including activation of dendritic cells, CD8 T-cell infiltration, induction of interferons, and enhancement of immunogenic cell death. Intratumoral (IT) BO-112 has been tested both alone and in combination with anti-PD-1 therapies in a phase I trial (NCT02828098), which showed an overall response rate (ORR) of 11% and disease control rate (DCR) of 46% in patients with multiple tumor types and a tolerable safety profile. While anti-PD1 therapies have shown promise in select subtypes of soft tissue sarcoma (STS), their overall efficacy in STS has been limited. We hypothesize that BO-112, in combination with radiotherapy (RT), may reverse resistance to anti-PD1 therapy in a subset of patients with STS.

Methods: This is an exploratory phase I study of IT BO-112 in combination with nivolumab in patients with STS planning to undergo neoadjuvant RT (NCT04420975) and surgery. BO-112 at a dose of 1 mg will be administered intratumorally on days 1, 8 and 15; nivolumab 240 mg will be administered intravenously on days 8 and 22. Patients will receive 5 fractions of neoadjuvant RT between day 8 and 12, followed by surgical resection between days 26 and 50. Twenty patients with newly diagnosed high grade histologically confirmed STS of the extremity, trunk or retroperitoneum amenable for IT injection will be included. Allowed histological subtypes are undifferentiated pleomorphic sarcoma, myxofibrosarcoma, leiomyosarcoma, dedifferentiated liposarcoma and synovial sarcoma.The primary objective is to explore the safety of BO-112 in combination with nivolumab in patients undergoing preoperative RT. The study includes stopping rules based on the frequency of dose limiting toxicities. As an exploratory single arm pilot study results will be reported using purely descriptive statistics. Tumor and blood specimens collected at baseline, at each IT BO-112 injection, and surgery will allow evaluation of the dynamic changes in tumor immune infiltration, T cell receptor repertoire, and tumor necrosis. These dynamic changes, along with putative biomarkers, such as baseline tumor mutational load, copy number alterations, tumor immune composition, tumor and immune gene expression signatures, and PD-L1 expression, will be related to individual subject tumor responses. The 2-year rate of local recurrence and distant metastasis will also be assessed. This study began accrual in December 2020 and is open.

Citation Format: Anusha Kalbasi, Fritz C. Eilber, Arun Singh, Bartosz Chmielowski, Nicholas Bernthal, Brooke Crawford, Joseph G. Crompton, Varand Ghazikhanian, Leanne Seeger, Kambiz Motamedi, Michael L. Douek, Carol Felix, Vincent Basehart, Helena Escuin-Ordinas, Marisol Quintero, Sonia Macia. A phase I study of intratumoral BO-112 and nivolumab for resectable soft tissue sarcoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr CT221.

COM701 with or without nivolumab: Results of an ongoing phase 1 study of safety, tolerability and preliminary antitumor activity in patients with advanced solid malignancies (NCT03667716)

2504

Background: COM701 is a novel first in class humanized IgG4 monoclonal antibody that binds with high affinity to poliovirus receptor related immunoglobulin domain containing (PVRIG), blocking its interaction with its ligand, PVRL2. Blocking of PVRIG leads to enhanced activation of T/NK cells and in mouse models inhibits tumor growth. We report new and updated results on safety/tolerability/pharmacokinetics and antitumor activity from this ongoing study including final results in dose escalation combination cohort, monotherapy expansion cohort (MEC). Methods: We enrolled a total of 51 DLT-evaluable pts: Arm A (COM701 mono dose escalation), 16 pts in 8 cohorts (0.01 – 20 mg/kg IV Q3/4 wks); Arm B (COM701 0.3 – 20 mg/kg + nivolumab (NIVO) 360 mg/480 mg IV Q3/Q4 wks), 15 pts in 5 cohorts; 20 pts in MEC (NSCLC, OVCA, breast, endometrial and CRC) at the recommended dose for expansion(RDFE), 20 mg/kg IV Q4 wks. Key inclusion criteria: Age ≥18 yrs, histologically confirmed metastatic solid malignancy, has exhausted available standard tx, ECOG 0-1, prior ICI permissible (except prior tx with a PVRIG inhibitor). Key exclusion criteria: active autoimmune disease requiring systemic tx, hx inflammatory lung disease. Primary objectives – safety/tolerability of COM701 ± NIVO (AEs, CTCAE v4.03), PK, RDFE. Key secondary/exploratory objectives - antitumor activity of COM701 ± NIVO (RECIST v1.1), evaluation of PVRL2 expression in tumor biopsy, blood cytokines and immunophenotyping. Results: No DLTs were reported in Arms A or B. COM701 PK profile similar in Arm A, 20 mg/kg IV Q4 wks (cohort 8) and Arm B cohort 5 (COM701 20 mg/kg + NIVO 480 mg; all IV Q4 wks). Frequency of TEAEs in safety population (N=54 pts): pts on COM701 mono (N=38)- No AE (4), Grade≤2 (21), G3 (11), G4 (1), G5 (1, PD), pts on combo (N=16) - Grade≤2 (8), G3 (7), G5 (1, PD). Serious TEAE: pts on COM701 mono 11/38, pts on combo 6/16. Most frequent AEs in Arm A: Grade ≤2 fatigue 12/38 pts (31%), nausea 9/38 (23%); Arm B: fatigue 7/16 pts (44%) and AST increased 4/16 pts (25%). Antitumor activity - in Arm A (cohort 8), a pt with platinum resistant primary peritoneal cancer had confirmed PR ongoing 14 months. In Arm B (COM701 10 mg/kg + NIVO 480 mg, all IV Q4 wks), a pt with anal SCCA; confirmed CR, ongoing 18 months, last tx with prior PD on NIVO. In addition, a pt with renal cell CA had confirmed SD [ongoing 13 months, COM701 0.3 mg/kg + NIVO 360mg; IV Q3 wks],] In MEC, 30% (6/20 pts) had best response of SD [1-endometrial, 3 NSCLC, 2 OVCA], 2 pts [NSCLC, OVCA] ongoing at 6/4 months. Overall 16pts had prior tx-refractory disease, 9(56%) had best response of ≥SD. Of 18 pts with prior tx with ICI, 13 (72%) had best response of ≥SD. Datacut 14Dec2020. Conclusions: COM701 ± NIVO well tolerated with no new safety signals. Encouraging signal of antitumor activity including in pts with prior tx with ICI or prior tx-refractory disease. Clinical trial information: NCT03667716..

Phase (Ph) 1b/2 evaluation of olaratumab in combination with gemcitabine and docetaxel in advanced soft tissue sarcoma (STS)

11517

Background: Doxorubicin (doxo) remains standard first-line therapy for advanced STS. Doxo in combination with olaratumab (O) demonstrated superior clinical activity compared to doxo alone in a Ph 2 trial (NCT01185964), although this was not confirmed in the subsequent Ph 3 trial (NCT02451943). Gemcitabine (G) plus docetaxel (D) is a second line therapy for advanced STS. Here, we report a concurrent Ph 2 study that explored a second-line addition of O to G and D for advanced STS (ANNOUNCE 2 NCT02659020). Methods: Adult patients (pts) with unresectable locally advanced or metastatic STS, ≤ 2 prior lines of systemic therapy, and ECOG PS 0-1 were eligible. Pts were enrolled from 2 cohorts: O-naïve and O-pretreated. In both cohorts, pts were randomized 1:1 to either O, G plus D or placebo (PBO), G plus D. Pts received 21-day cycles of O (20 mg/ kg cycle 1 and 15 mg/kg other cycles, day (d) 1 and d8), G (900 mg/m2, d1 and d8) and D (75 mg/m2, d8). Pts continued treatment until progression, toxicity, or withdrawal. Randomization was stratified by histology (leiomyosarcoma [LMS] vs non-LMS), prior systemic therapy, ECOG PS, and prior pelvic radiation. The primary objective was overall survival (OS) in the O-naïve population using an alpha level of 0.20. Secondary endpoints included OS (O-pretreated) and other efficacy parameters, as well as safety and pharmacokinetics (PK). Results: 167 pts were enrolled in the O-naïve cohort and 89 pts in the O-pretreated cohort. Baseline patient characteristics were well balanced. OS for O-naïve pts was 16.8 vs 18.0 months (m) (hazard ratio [HR] = 0.95, 95% CI: 0.64-1.40; p = 0.78) for the investigational vs control arm, respectively. Other efficacy outcomes are presented in the table. Safety was manageable across treatment arms. PK parameter estimates for O were consistent with previous studies. Conclusions: There was no statistically significant difference in OS between the two arms in the O-naïve population. However, while not statistically significant, the combination of O, G and D demonstrated favorable OS in the O-pretreated cohort, and PFS and objective response rate (ORR) in both cohorts. For O-naïve pts, a clinically meaningful progression-free survival (PFS) improvement was observed. Further investigations in specific histological subtypes are ongoing. Clinical trial information: NCT02659020. [Table: see text]

Recurrence and disease-specific survival after 10-year disease-free interval in patients with primary retroperitoneal liposarcoma: Implications for long-term surveillance

11546

Background: Surveillance imaging of patients with retroperitoneal liposarcoma (RP-LPS) following surgical resection is based on a projected risk of locoregional and distant recurrence. The duration of surveillance is not well defined as the long-term natural history of RP-LPS after treatment is poorly understood. We evaluate a cohort of RP-LPS patients—without evidence of disease 10 years following initial resection—to assess the long-term risk of recurrence and disease-specific survival (DSS). Methods: The prospectively maintained UCLA Sarcoma Database was used to identify RP-LPS patients who demonstrated 10-year progression-free survival (10yr-PFS) after initial diagnosis and treatment. Patients in the 10yr-PFS cohort were subsequently evaluated for recurrence and DSS. Time intervals start at date of initial surgical resection. Cox proportional hazards models were used to determine factors associated with recurrence and DSS. Results: From 1972-2010, 76 patients with RP-LPS had at least 10 years of follow-up. Of these, 37 (49%) demonstrated 10yr-PFS. Median follow-up was 15 years (range 10-35 years). Among the 10yr-PFS patients, 43% (16/37) developed a recurrence >10 years after the initial surgery, and 19% (7/37) died of disease. Neither long-term recurrence nor DSS were significantly associated with age, sex, tumor size, LPS subtype, surgical margin, or peri-operative treatment with radiation or chemotherapy (Table). Conclusions: Patients with primary RP-LPS treated with surgical resection +/- multimodality therapy have a long-term risk of recurrence and disease-specific death that is unacknowledged by current surveillance imaging guidelines. Among the patients with a 10yr-PFS, 43% developed a recurrence and 19% died of disease. These findings suggest a need for lifelong surveillance imaging in patients with RP-LPS.[Table: see text]

Final analysis of overall survival (OS) and relapse-free-survival (RFS) in the intergroup S1404 phase III randomized trial comparing either high-dose interferon (HDI) or ipilimumab to pembrolizumab in patients with high-risk resected melanoma

9501

Background: We assessed whether or not adjuvant pembrolizumab given over 1 year would improve OS and RFS in comparison to high dose ipilimumab (ipi10) or HDI - the two FDA-approved adjuvant treatments for high risk resected melanoma at the time of study design. Methods: Patients age 18 or greater with resected stages IIIA(N2), B, C and IV were eligible. Patients with CNS metastasis were excluded. At entry, patients must have had complete staging and adequate surgery to render them free of melanoma including completion lymph node dissection for those with sentinel node positive disease. Prior therapy with PD-1 blockade, ipilimumab or interferon was not allowed. Two treatment arms were assigned based on stratification by stage, PD-L1 status (positive vs. negative vs. unknown), and intended control arm (HDI vs. Ipi10). Patients enrolled between 10/2015 and 8/2017 were randomized 1:1 to either the control arm [(1) interferon alfa-2b 20 MU/m2 IV days 1-5, weeks 1-4, followed by 10 MU/m2/d SC days 1, 3, and 5, weeks 5-52 (n=190), or (2) ipilimumab 10 mg/kg IV q3w for 4 doses, then q12w for up to 3 years (n=465)], or the experimental arm [pembrolizumab 200 mg IV q3w for 52 weeks (n=648)]. The study had three primary comparisons: 1) RFS among all patients, 2) OS among all patients, 3) OS among patients with PD-L1+ baseline biopsies. Results: 1,426 patients were screened and 1,345 patients were randomized with 11%, 49%, 34%, and 6% AJCC7 stage IIIA(N2), IIIB, IIIC and IV, respectively. This final analysis was performed per-protocol 3.5 years from the date the last patient was randomized, with 512 RFS and 199 OS events. The pembrolizumab group had a statistically significant improvement in RFS compared to the control group (pooled HDI and ipi10) with HR 0.740 (99.618% CI, 0.571 to 0.958). There was no statistically signifcant improvement in OS in the 1,303 eligible randomized overall patient population with HR 0.837 (96.3% CI, 0.622 to 1.297), or among the 1,070 (82%) patients with PD-L1 positive baseline biopsies with HR 0.883 (97.8% CI, 0.604 to 1.291). Gr 3/4/5 event rates were as follows: HDI 69/9/0%, ipi10 43/5/0.5% and pembrolizumab 17/2/0.3%. Conclusions: Pembrolizumab improves RFS but not OS compared to HDI or ipi10 in the adjuvant treatment of patients with high-risk resected melanoma. Pembrolizumab is a better tolerated adjuvant treatment regimen than HDI or Ipi10. Support: NIH/NCI NCTN grants CA180888, CA180819, CA180820, CA180863; and in part by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Kenilworth, NJ, USA. Editorial Acknowledgement: With special thanks to Elad Sharon, MD, MPH, and Larissa Korde, MD, MPH. National Cancer Institute, Investigational Drug Branch, for their contributions to this trial, as well as Nageatte Ibrahim, MD, and Sama Ahsan, MD Merck. Clinical trial information: NCT02506153.

Preliminary results of a phase II study of alrizomadlin (APG-115), a novel, small-molecule MDM2 inhibitor, in combination with pembrolizumab in patients (pts) with unresectable or metastatic melanoma or advanced solid tumors that have failed immuno-oncologic (I-O) drugs

2506

Background: Alrizomadlin (APG-115) restores TP53 function, activating p53-mediated apoptosis in tumor cells with wild-type TP53 and/or MDM2 amplification. Alrizomadlin also functions as a host immunomodulator and hence may restore antitumor activity in pts with cancers failing PD-1/PD-L1 blockade. Methods: This US multicenter trial assessed alrizomadlin combined with pembrolizumab in pts with unresectable/metastatic melanoma or advanced solid tumors that had failed I-O drugs; or pts with malignant peripheral nerve sheath tumor (MPNST), liposarcoma, or ATM mutant solid tumors that had failed any standard therapy. Eligible pts had ECOG performance status of 0-2 and no CNS metastases. The phase II study cohorts included pts with melanoma, NSCLC, solid tumor with ATM mutation, well-differentiated/dedifferentiated liposarcoma, urothelial carcinoma, and MPNST. Alrizomadlin was administered orally at 150 mg once every other day for 2 consecutive weeks with 1 week off and pembrolizumab at 200 mg via IV infusion for 30 minutes on Day 1 of a 21-day cycle. Results: As of December 25, 2020, 84 pts had been treated in 6 cohorts: melanoma (n = 26), NSCLC (n = 23), ATM mutation (n = 9), liposarcoma (n = 14), urothelial (n = 9), and MPNST (n = 3). In the PD-1/PD-L1 inhibitor-failed melanoma cohort, there was 1 confirmed partial response (PR) out of 5 pts with uveal melanoma, 2 PR (1 confirmed and 1 unconfirmed) of 5 pts with mucosal melanoma, and 1 confirmed PR of 11 pts with cutaneous melanoma. ORR in the melanoma cohort was 17.4% (4/23 evaluable pts), and the disease control rate was 60.9% (14/23). In the MPNST cohort, 1 of 3 pts had an unconfirmed ongoing PR. In I-O drug-failed NSCLC (n = 14 evaluable) and urothelial (n = 5 evaluable) cohorts, each reported 1 confirmed PR. Common treatment (alrizomadlin or pembrolizumab)-related adverse events (TRAEs) (≥ 10%) were nausea (63.1%), thrombocytopenia (36.9%), vomiting (33.3%), fatigue (31.0%), decreased appetite (27.4%), diarrhea (21.4%), neutropenia (15.4%), and anemia (11.9%). Grade ≥ 3 TRAEs (≥ 5%) included thrombocytopenia (20.2%), neutropenia (14.2%), and anemia (8.3%). Eleven pts discontinued treatment due to AEs: 5 were treatment related, including 2 grade 4 thrombocytopenia, and 1 each of grade 2 vomiting, grade 2 fatigue, and grade 2 posterior reversible encephalopathy syndrome (PRES). Three treatment-related SAEs were PRES, pyrexia, and asthenia. Conclusions: Alrizomadlin combined with pembrolizumab is well tolerated and may restore antitumor effects in pts with cancer resistant to or intolerant of I-O drugs, as suggested by preliminary antitumor activities in multiple tumor types. Internal study identifiers: APG-115-US-002; Keynote MK-3475-B66. Clinical trial information: NCT03611868.

A phase III study (APROMISS) of AL3818 (Catequentinib, Anlotinib) hydrochloride monotherapy in subjects with metastatic or advanced synovial sarcoma

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Background: AL3818 (Catequentinib, Anlotinib) is a novel, orally administered, small molecule tyrosine kinase inhibitor. The primary objective of this Phase 3 study is to evaluate the efficacy of AL3818 monotherapy in patients (pts) with synovial sarcoma (SS) comparing with dacarbazine in randomization setting. Methods: Patients with a diagnosis of synovial sarcoma requiring second line or further line treatment were eligible for enrollment. The regimen was a 21-day cycle with oral AL3818 administered on 14 days on and 7 days off. This phase 3 trial is randomized in 2:1 ratio of AL3818 comparing to dacarbazine with option of crossover after PD of dacarbazine treatment. Progression free survival (PFS) with Log Rank test is the primary endpoint and this trial for SS is currently completed enrolled in US and Italy. Results: Total 79 pts initiated treatment and are evaluable, 52 received AL3818 as treatment arm (T), and 27 received dacarbazine (D) as control arm (C). Arms T/C median ages were 40.5/42.0 years (range: 18-70+) and 20/16 (38.5%/59.3%) were male. Overall, PFS was 2.89 months (95% CI: 2.73 – 6.87) for AL3818 and 1.64 (95% CI: 1.45 – 2.70) for D. The PFS of study met the primary endpoint with a p-value of 0.0015 and a HR of 0.449 (95% CI: 0.270– 0.744). At the month 4, 6, and 12, the percentages of progression free patients for AL3818 were 48.1%, 42.3% and 26.9%; and for D were 14.85%, 11.1% and 3.7%. For grade 3 treatment-related adverse events, 12(23.1%) of pts experienced for AL3818 and 7(25.9%) of pts experienced for D. The most common AL3818 related grade 3 AEs were diarrhea (5.8%) and hypertension (3.8%). Conclusions: This phase III trial demonstrates improved disease control and superior progression free survival for AL3818 vs dacarbazine in advanced SS. In addition, the study further confirms the acceptable benefit-risk profile of AL3818 from the prior randomized Phase 2b soft tissue sarcoma study (NCT02449343). AL3818 is a meaningful treatment option for pts with advanced SS. Clinical trial information: NCT 03016819 Clinical trial information: NCT03016819.

Health-related quality of life and pain with selinexor in patients with advanced dedifferentiated liposarcoma

Objective:

Compare health-related quality of life (HRQoL) of selinexor versus placebo in patients with dedifferentiated liposarcoma.

Materials & methods:

HRQoL was assessed at baseline and day 1 of each cycle using the European Organization for Research and Treatment of Cancer 30-item core quality of life questionnaire. Results were reported from baseline to day 169 (where exposure to treatment was maximized while maintaining adequate sample size).

Results:

Pain scores worsened for placebo versus selinexor across all postbaseline visits, although differences in HRQoL at some visits were not significant. Other domains did not exhibit significant differences between arms; however, scores in both arms deteriorated over time.

Conclusion:

Patients treated with selinexor reported lower rates and slower worsening of pain compared with patients who received placebo.

The goal of this study was to compare the health-related quality of life (HRQoL) of patients with advanced unresectable dedifferentiated liposarcoma treated with selinexor compared with those treated with placebo. HRQoL was measured prior to treatment initiation and at the first day of each cycle of their treatment using the European Organization for Research and Treatment of Cancer 30-item core quality of life questionnaire. Pain scores worsened for placebo compared with selinexor across all visits after treatment, but differences at some visits were not significant. Other domains did not exhibit significant differences between arms; however, scores in both arms worsened over time reflecting the progressive disease burden in this patient population. As pain is one of the most devastating symptoms associated with advanced and progressing cancers, the significant reduction in pain in the selinexor arm, according to patient perception, represent a relevant added value of this drug in dedifferentiated liposarcoma.

NCCN Guidelines® Insights: Melanoma: Cutaneous, Version 2.2021

Over the past few years, the NCCN Guidelines for Melanoma: Cutaneous have been expanded to include pathways for treatment of microscopic satellitosis (added in v2.2020), and the following Principles sections: Molecular Testing (added in v2.2019), Systemic Therapy Considerations (added in v2.2020), and Brain Metastases Management (added in v3.2020). The v1.2021 update included additional modifications of these sections and notable revisions to Principles of: Pathology, Surgical Margins for Wide Excision of Primary Melanoma, Sentinel Lymph Node Biopsy, Completion/Therapeutic Lymph Node Dissection, and Radiation Therapy. These NCCN Guidelines Insights discuss the important changes to pathology and surgery recommendations, as well as additions to systemic therapy options for patients with advanced disease.

407 Preliminary safety, pharmacokinetics/pharmacodynamics, and antitumor activity of XmAb20717, a PD-1 x CTLA-4 bispecific antibody, in patients with advanced solid tumors

Background

XmAb20717 is a humanized bispecific monoclonal antibody that simultaneously targets PD-1 and CTLA-4. We report preliminary data from an ongoing, multicenter, Phase 1 study investigating the safety/tolerability, pharmacokinetics/pharmacodynamics, and clinical activity (RECIST 1.1) of XmAb20717 in patients with selected advanced solid tumors.

Methods

A 3+3 dose-escalation design was used to establish a maximum tolerated (MTD)/recommended dose for evaluation in parallel expansion cohorts, including melanoma, renal cell carcinoma, non-small cell lung cancer (NSCLC), prostate cancer, and a basket of tumor types without an FDA-approved checkpoint inhibitor (CI; n≤20 each). XmAb20717 was administered as an infusion on Days 1 and 15 of each 28-day cycle.

Results

As of 08Jul2020, 109 patients had been treated (table 1), and 30 were continuing treatment. In escalation, 6 dose levels (0.15–10.0 mg/kg) were evaluated (n=34); an MTD was not established. Expansion cohorts were initiated at 10 mg/kg (n=72), and a 15 mg/kg escalation cohort was added (n=3). T-cell proliferation was noted in peripheral blood at doses as low as 3 mg/kg and was highest at 10 mg/kg. At this dose, consistent proliferation of CD8+ and CD4+ T cells was observed, indicative of dual PD-1 and CTLA-4 checkpoint blockade (figure 1). Paired pre- and post-dosing biopsies showed increased intratumoral T-cell infiltration and IFN-response signatures following treatment. Grade 3/4 treatment-related adverse events (TRAEs) reported for ≥3 patients included rash (13%), transaminase elevations (7%), lipase increased (4% [2% with amylase increased]), and acute kidney injury (3%), all considered immune-related. There were 2 Grade 5 TRAEs: immune-mediated pancreatitis (in the presence of pancreatic metastases) and immune-mediated myocarditis (Grade 4) that contributed to respiratory failure. A complete response was reported as the best overall response for 1 patient (melanoma); partial responses were reported for 5 patients (2 melanoma, 2 NSCLC, 1 ovarian). The objective response rate was 13% overall and 21% at 10 mg/kg (6/46 and 6/29 evaluable patients, respectively). All responders had prior CI exposure. Responses were observed only at 10 mg/kg and, within the 10 mg/kg group, appeared to correlate with higher peak serum concentration and area under the curve.

Abstract 407 Table 1

Demographics and baseline characteristics

Abstract 407 Figure 1

Mean change from baseline in percentage of Ki67+ T–cell expression in peripheral blood during first two cycles of XmAb20717

Conclusions

XmAb20717 induced T-cell proliferation in peripheral blood consistent with dual-checkpoint blockade. Preliminary data indicate XmAb20717 was generally well-tolerated and associated with evidence of antitumor activity in CI-pretreated patients with various types of advanced solid tumors.

Trial Registration

NCT03517488

Ethics Approval

The study was approved by each institution’s IRB.