Dronca, Roxana

Background Trans-acting programmed death-ligand 1 (PD-L1) derives from malignant cells in three known forms. High levels of secreted splice variant PD-L1 (sPD-L1), ADAM10/ADAM17-shed sPD-L1, and PD-L1-positive extracellular vesicles (evPD-L1) each predict poor prognosis and limited response to PD-(L)1 checkpoint inhibitors in cancer. To our knowledge, no clinical intervention has reduced any of these circulating forms of extracellular PD-L1. Here, we explore therapeutic plasma exchange (TPE) as a treatment to reduce circulating extracellular PD-L1. Results In patients with melanoma, sPD-L1 levels above 0.277 ng/mL predicted inferior overall survival. In patients undergoing TPE for non-malignant indications, each TPE session removed a mean 70.8% sPD-L1 and 73.1% evPD-L1 detectable in plasma. TPE also reduced total and ADAM10-positive extracellular vesicles. Conclusion Here, we report the first known clinical intervention to remove either sPD-L1 or evPD-L1 from plasma in vivo. TPE reduces plasma sPD-L1 and evPD-L1 in vivo and may have a role in treatment with immunotherapy. TPE may also prove useful in patients with other extracellular vesicle-related conditions.

Abstract Background: Sex differences in non-small cell lung cancer (NSCLC) outcomes have been described. Immune-related adverse events (IRAEs) have emerged as a serious clinical problem in the use of immune checkpoint inhibitors (ICI). Risk factors for IRAEs and their association with response to therapy remain controversial. Sex differences in innate and adaptive immune responses have been observed but the association of these differences with IRAEs remains unclear. Therefore, we studied sex differences in IRAEs and their association with response to therapy. Methods: All patients with metastatic NSCLC treated with anti-PD1 and anti-PDL1 therapy at Mayo Clinic Rochester and Florida from 2015 to 2018 were reviewed. Patients receiving treatment at an outside facility with history autoimmune disorders or radiation-induced pneumonitis were excluded. Chi-square test was used to estimate differences in categorical data. Kaplan-Meier method was used for time-to-event analysis. Results: A total of 231 patients were identified; 120 (52%) were women and 111 (48%) were men. Baseline characteristics and ICI distribution were similar among groups. Women were more likely to experience IRAEs compared to men (48% vs. 31%, p<0.008). Among patients with IRAEs, women were more likely to be prescribed systemic steroids (63% vs. 41%, p<0.02). On the other hand, no significant differences were observed in the administration of intravenous steroids. Women were more likely to develop pneumonitis (23% vs. 12%, p<0.03) and arthralgias (17% vs. 3%, p<0.04). However, dermatologic toxicities (35% vs. 9%, p<0.002) were more commonly seen in men. In 17% of women the ICI was discontinued due to toxicity (men 7%). Besides sex, no other clinical characteristic was associated with increased IRAEs. Women with IRAEs were more likely to have a radiographic response compared with women without IRAEs (78% vs. 23%, p<0.0001), although this was not observed in men (37% vs. 26%, p>0.22). Better PFS was observed in women with IRAEs (10 months vs. 3.3 months, p<0.0006) compared to women without IRAEs. Conclusions: Women with metastatic NSCLC are more likely to experience IRAEs compared to men. We also observed sex differences in the frequency of certain IRAEs. In addition, an association between IRAEs and response to therapy was observed in women. Larger studies are needed to investigate the mechanisms underlying these associations. Citation Format: Narjust Duma, Abdel-Ghani Azzouqa, Siddhartha Yadav, Kahterine Hoversten, Clay Reed, Andrea Sitek, Elizabeth Enninga, Jonas Paludo, Lisa Kottschade, Aaron Mansfield, Rami Manochakian, Roxana Dronca, Alex Adjei. Sex differences in tolerability and response to immune checkpoint inhibitors in non-small cell lung cancer patients [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr A120.

Management of PD-1 blockade resistance in metastatic melanoma (MM) remains challenging. Immunotherapy or chemotherapy alone provides limited benefit in this setting. Chemo-immunotherapy (CIT) has demonstrated favorable efficacy and safety profiles in lung cancer. Our pre-clinical study showed that in MM patients who have failed PD-1 blockade, the addition of chemotherapy increases CX3CR1+ therapy-responsive CD8+ T-cells with enhanced anti-tumor activity, resulting in improved clinical response. Here, we examined the clinical outcomes of CIT in MM patients after PD-1 blockade failure and the treatment-related changes in CX3CR1+ therapy-responsive CD8+ T-cells. We reviewed MM patients seen between January 2012 and June 2018 who failed anti-PD-1-based therapy and received subsequent CIT, immune checkpoint inhibitors (ICI) or chemotherapy alone. Overall survival (OS), objective response rate (ORR), event-free survival (EFS), and toxicities were assessed. Among 60 patients, 33 received CIT upon disease progression on PD-1 blockade. At a median follow-up of 3.9 years, the CIT group had a median OS of 3.5 years [95% confidence interval (CI) 1.7–NR] vs. 1.8 years (95% CI 0.9–2; P = 0.002) for those who received subsequent ICI (n = 9) or chemotherapy alone (n = 18), with ORR of 59% vs. 15% (P = 0.0003), respectively. The median EFS was 7.6 months (95% CI 6–10) following CIT vs. 3.4 months (95% CI 2.8–4.1; P = 0.0005) following ICI or chemotherapy alone. Therapy-responsive CX3CR1+CD8+ T-cells showed dynamic increase with successful CIT. CIT showed favorable clinical outcomes and acceptable safety profile in PD-1 blockade-resistant patients. CX3CR1+CD8+ therapy-responsive T-cells can be potentially used for monitoring disease response to CIT.

Abstract Background: The biology, pathology and clinical course of CD5+ chronic B cell lymphoproliferative disorders (CD5+ B-CLPD) excluding chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL) and mantle cell lymphoma (MCL) are poorly defined. These patients could either have a leukemic variant of a known B cell malignancy or a novel disease entity. Objective: To define the clinical features and pathology of CD5+ B-CLPD, compare these features to CLL, and test the hypothesis that at least some of these patients have a unique B cell malignancy. Methods: The study was conducted with Institutional Review Board permission. We studied 231 patients evaluated in the Division of Hematology at Mayo Clinic Rochester between 1996 and 2008 who had CD5+ monoclonal B cell population in the peripheral blood and/or bone marrow, and in whom CLL and MCL was not diagnosed after flow cytometry, histology and interphase fluorescence in situ hybridization (FISH) examinations. Data were abstracted from patient records and from the Mayo Clinic CLL database. Statistical analysis: To compare differences in characteristics between CD5+ and CLL patients, χ2 statistics were used for qualitative variables (gender, treatment, vital status) and t-tests were used for quantitative variables (age). We performed survival and time to treatment analyses with results displayed using Kaplan-Meier curves and p-values calculated using a log-rank test. Results: We analyzed data on 231 CD5+ B-CLPD patients diagnosed between 7/1/1976 and 5/2/2008 and 1572 CLL patients diagnosed in the same time period. Median follow-up from diagnosis was 2.5 years (range 0 to 25.1 years) for the CD5+ patients and 5.2 years (range 0 to 29.9 years) for CLL patients. CD5+ B-CLPD patients had a median age at diagnosis of 68 years (range 30–94 years) with male predominance (61.5%). One hundred and nine of 231 (52.4%) patients received treatment for their CD5+ B-CLPD and 162 (70.1%) patients were alive at the time of last follow-up. As a group, CD5+ B-CLPD patients had a similar male predominance to CLL but were older at diagnosis. CD5+ B-CLPD patients required their first treatment significantly sooner than CLL patients (median 2.0 years vs. 6.8 years, (p< 0.001) and a higher percentage of CD5+ B-CLPD patients required treatment (52.4% vs. 37.5%, p<0.0001). In addition, CD5+ B-CLPD patients had a shorter survival from diagnosis than CLL patients (median 8.4 years vs. 12.5 years, p<0.001). In 60 patients the CD5+ B-CLPD disease was the leukemic phase of a known lymphoma (lymphoplasmacytic lymphoma, n=34; nodal marginal zone lymphoma, n=6; splenic marginal zone lymphoma, n=16; MALT lymphoma, n=4), 46 patients had incomplete data, and 125 patients did not have pathological and flow cytometry features of a known lymphoid malignancy. Next we compared clinical outcome among the 125 patients with unclassifiable CD5+ B-CLPD to the CLL patients. The unclassifiable CD5+B-CLPD patients were older at diagnosis (median 69 vs. 65 years, p=0.0003) but there were no significant differences in time to treatment (median 9.0 years vs. 6.8 years, p=0.93) or the proportion of patients receiving treatment (30% vs. 37.5%, p=0.11). The survival from diagnosis was shorter for unclassifiable CD5+ B-CLPD patients (median 6.3 vs. 12.5 years, p<0.001). Conclusions: In this large series of CD5+ B-CLPD patients we found that a large subset did not meet diagnostic criteria for known B-cell malignancies and could have a novel disease. This will need to be investigated further. We reviewed the pathology of all available archived tissue and intend to examine additional clinical and prognostic information including molecular prognostic markers. Our data provide a clinical rationale for the careful differentiation between patients with CLL and CD5+ B-CLPD.

9073 Background: An accumulating body of evidence suggests that the outcome of early-stage melanoma is influenced by endocrine and menopausal status. However, it remains controversial as to whether the superior female melanoma-specific survival (MSS) is restricted to early stage disease or if it also pertains to patients with metastatic melanoma (MM). Methods: We analyzed data from the 13 registries that participate in the National Cancer Institute Surveillance, Epidemiology, and End Results (SEER) program. We identified all cases of primary invasive melanoma diagnosed between 1992 and 2009; none of the patients had a prior history of another cancer. MSS was compared between males and females, stratified by stage of disease. Age groups were defined as 18-45y, 46-54y, 55-64y, 65+y as a proxy of female menopausal status. Results: The study population included 87,165primary invasive melanoma cases (unstaged n=2834). MSS was significantly poorer for males compared to females for localized (n=72,456) and regional (n=8,945) disease for all age groups (Hazard ratio (HR) ranging from 1.21 to 2.09, all p<0.001). MSS was not significantly different between males and females for patients with distant disease at diagnosis (n= 2930; HR 0.99, 0.92, 1.11, 1.07 for each age group) and remained non-significant after adjusting for Breslow thickness, histologic subtype, anatomic site, and age group (adjusted HR 1.04 males vs. females; 95% CI 0.95-1.14; p=0.41). Conclusions: While our results were consistent with earlier reports that women have higher MSS rates compared to men for early (stage I-III) melanoma, the intriguing finding of this study was that the female survival advantage does not vary with age or menopausal status as compared to men, which is contrary to previously published reports. Furthermore, we found that the difference in survival was no longer significant for patients with MM, suggesting that sex may influence local and regional, but not distant cancer progression.

9048 Background: Brain metastases continue to be the major cause of morbidity and mortality in patients with metastatic melanoma. The impact of BRAF mutations and effectiveness of BRAF inhibitors on the brain metastases in these patients is lacking. Methods: Preclinical studies were conducted to assessthe steady-state brain and plasma distribution of vemurafenib, a BRAF inhibitor in FVB wild-type and Mdr1a/b-/-Bcrp1-/- mice deficient in the drug efflux transporters, p-glycoprotein (P-gp) and breast cancer resistant protein (BCRP). A retrospective analysis of patients with metastatic melanoma treated at University of Minnesota from August 2011 to December 2012 was conducted. A similar analysis of cases treated at Mayo Clinic is underway. Results: The preclinical studies in mice show that both P-gp and BCRP play a significant role in limiting the brain distribution of vemurafenib. Retrospective analysis was performed on 57 patients with Stage IIIc /IV cutaneous and mucosal melanoma. Patients with BRAF mutation had a higher incidence rate of brain metastases compared to patients without BRAF mutation, although it was not statistically significant (Incidence ratio=1.56; 95% CI=0.70-3.48; P=0.27). Vemurafenib neither reduced the incidence of brain metastases (Incidence ratio = 0.89; 95% CI: 0.30-2.60; P=0.83) nor made significant difference in overall survival. It was observed that treatment with BRAF inhibitor led to improvement in extracranial disease but did not affect progression of intracranial disease. Conclusions: In concordance with preclinical data which indicates that P-gp and BCRP play a significant role in limiting the brain distribution of vemurafenib, the retrospective analysis shows that there is improvement in extracranial disease but progression in intracranial disease with treatment with BRAF inhibitor in patients with metastatic malignant melanoma with BRAF mutation. Development of BRAF inhibitors that are not substrates for P-gp and BCRP or concomitant use of P-gp and BCRP inhibitors with vemurafenib, may be needed in order to control or prevent intracranial disease in these patients. Further analysis to improve statistical power of our observation is underway.

9016 Background: The MAP kinase (MAPK) pathway is of critical importance for keratinocyte proliferation and maturation and is essential for epidermal homeostasis. Occurrence of hyperproliferative skin lesions including keratoacanthomas (KA) and cuSCC are considered a class effect of BRAFi [Anforth 2012, Chu 2012, Mattei 2012]. These effects, as well as promotion of pre-existing RAS-driven malignancies, may be caused by paradoxical activation of the MAPK pathway downstream of BRAF in wild-type BRAF cells. As MEK inhibition blocks downstream MAPK signaling, it was hypothesized that addition of a MEKi to a BRAFi would abrogate these effects [Su, 2012]. Methods: This 4-part phase I/II study enrolled 365 BRAFV600E/Kmutated MM pts in Parts B-D. In part C, 162 pts (BRAFi and MEKi treatment-naïve, ≥ 18 yrs; ECOG PS <2; RECIST measurable disease) were randomized to D monotherapy 150mg BID (D mono) vs. the combination of D (150 mg BID) and T (1 mg or 2 mg QD). Primary endpoints included safety and efficacy. Occurrence of cuSCC (including KA) across three arms in Part C and secondary malignancies with D+T across all Parts are provided below. Results: The difference in incidence of cuSCC between D mono and the D+T (150/1) was statistically significant, whereas the difference in incidence between D mono and D+T (150/2) was not. The median time to onset of cuSCC was 30 days in D mono compared to 282 and 152 days with D+T (150/1 and 150/2, respectively). Of 365 pts who received D+T, 2 (<1%) cases of new cancers (colorectal and gliobastoma) and 2 (<1%) cases of new primary malignant melanoma were reported. Conclusions: These data support the experimental hypothesis that the occurrence of cuSCC (including KA) can be substantially reduced and delayed by the addition of a MEKi to BRAFi therapy. Clinical trial information: NCT01072175. [Table: see text]

9009 Background: Programmed death-1 (PD-1) is an inhibitory T-cell co-receptor that may lead to suppression of antitumor immunity. Lambrolizumab is a humanized monoclonal IgG4 antibody against PD-1. This study explored the safety and clinical activity of lambrolizumab in patients (pts) with advanced melanoma (MEL). Methods: In this ongoing phase 1b expansion study of MEL pts with or without previous ipilimumab (IPI) treatment, lambrolizumab was administered IV every 2 or 3 weeks until disease progression or unacceptable toxicity. Tumor response was assessed every 12 weeks by independent, central, blinded radiographic review per immune-related response criteria and RECIST 1.1. Results: As of December 1, 2012, 294 pts with MEL were enrolled, including 179 IPI-naive and 115 IPI-pretreated. Pts received lambrolizumab 10 mg/kg (n = 183) or 2 mg/kg (n = 111). Preliminary data from the first 85 consecutive pts dosed before April 25, 2012, who had independent radiologic review available as of December 3, 2012, indicate a confirmed overall response rate per RECIST 1.1 of greater than 35%, pooled across all doses and schedules and including both IPI-naive and IPI-pretreated patients. The median duration of response has not been reached as only 2 pts who had initial response discontinued due to disease progression, but the duration of confirmed responses range from 28+ to 240+ days (up to 8+ months). Among 133 pts who were dosed with lambrolizumab before July 31, 2012, and evaluable for adverse events (AEs) as of September 28, 2012, fatigue (22%), rash (18%), and pruritus (14%) were the most common drug-related AEs (mostly grade 1/2). The incidence of drug-related grade 3/4 AEs was 10% (24% regardless of attribution). Four drug-related cases of pneumonitis were reported, all of grade 1/2. Grade 3/4 drug-related hypothyroidism (n = 1) and hyperthyroidism (n = 1) were noted. Conclusions: Preliminary data suggest that lambrolizumab has significant antitumor activity and is well tolerated with manageable side effects in both IPI-naive and IPI-pretreated MEL pts. These data have led to an ongoing, international, randomized study of lambrolizumab versus chemotherapy in IPI-pretreated MEL. Clinical trial information: NCT01295827.