Citations

e21631 Background: The efficacy of osimertinib in previously EGFR-TKI treated NSCLC patients without T790M mutation remains unclear in real-world practice. We investigated whether osimertinib can provide survival benefit in EGFR-mutant patients without T790M mutation after 1st/2nd generation TKI treatment. Methods: Between January 1, 2009, and March 31, 2019, 417 patients had stage III-IV NSCLC harboring EGFR mutation and 154 out of 417 patients receiving osimertinib as≥2nd-line EGFR-TKI treatment were identified at Mayo Clinic. The time to treatment failure of osimertinib was analyzed by the Kaplan-Meier (KM) estimates. The risk of death post diagnosis was analyzed by Cox proportional hazard models. Results: Among 417 EGFR-mutant patients, higher risk of death was found in patients with age above 65 years, non-adenocarcinoma, no surgery treatment, no radiation treatment, non-exon 19 deletion/exon 21 L858R mutation, higher ECOG PS (2-4), PD-L1 expression of 50% or more, bone metastasis, live metastasis, and adrenal metastasis (all p < 0.05). Moreover, osimertinib as ≥2nd-line TKI treatment in patients with or without T790M revealed lower risk of death compared to 1st/2nd generation TKI treatment without subsequent osimertinib (HR = 0.33; 0.46, and p = 0.0002; 0.0232, respectively). However, among patients receiving osimertinib as ≥2nd-line TKI treatment, patients with T790M did not have superior survival than those without (p = 0.2803). Among 154 patients receiving osimertinib, a higher risk of treatment failure for osimertinib was found in male (HR = 1.72; p = 0.0327), patients with 1st-line TKI duration ≤12 months (HR = 2.16; p = 0.0019), BMI drop > 10% (HR = 1.85; p = 0.0207), PD-L1 levels of 50% or more (HR = 4.28; p = 0.0008), and 1st-line TKI with afatinib (HR = 2.19; p = 0.0136). Nonetheless, osimertinib as ≥2nd-line TKI in patients without 790M mutation did not have higher risk of treatment failure than those with T790M (p = 0.1236). Conclusions: This is the first study to demonstrate that osimertinib can provide similar survival benefit in previously EGFR-TKI treated NSCLC patients without T790M mutation as those with T790M in real-world practice. Additionally, EGFR-mutant patients with PD-L1 expression ≥50% had a higher risk of treatment failure for osimertinib and worse overall survival than those with PD-L1 expression < 50% and may potentially gain benefit from optimizing treatment strategies including immunotherapy.

e21575 Background: The clinical significance of brain metastases in patients with bronchopulmonary neuroendocrine (NE) tumors is unknown; we therefore conducted a population based analysis to evaluate the implications of brain metastases in these patients. Methods: The NCDB database was queried to identify patients with stage IV bronchopulmonary NE tumors treated between the years of 2004-2012. Patients were split into two groups based on the presence of brain metastases at diagnosis and survival probabilities with multivariate models were performed. Results: A total of 7,725 patients with Stage IV bronchopulmonary NE tumors were identified. The histological subtypes studied in this cohort were NE carcinoma (65.4%), large cell NE carcinoma (30.5%), typical carcinoid (2.8%) and atypical carcinoid (1.3%) . The patients included in this study were mainly white (86.4%) men (56.8%) with a median age of 67 years who had liver (9.5%), bone (6.2%) and brain (5.9%) metastases at diagnosis. The median overall survival (OS) of the cohort was 5.59 (95% CI: 5.4-5.8) months, but when OS was stratified by histological subtype it was significantly better in patients with typical carcinoid (table). In the whole cohort, the median OS did not differ between patients with and without brain metastases (5.55 vs. 5.68; p = 0.24). However, a sensitivity analysis by histology showed that the presence of brain metastases worsen the median OS of patients with typical carcinoid only (15.1 vs 4.6, p = 0.04). An adjusted multivariate analysis restricted to patients with brain metastases showed that administration of systemic chemotherapy (HR:0.5; 95% CI:0.35-0.72, p < 0.001) and resection of distant metastases (HR:0.5; 95% CI:0.29-0.88, p = 0.017) were the two most powerful independent prognostic factors. Conclusions: The presence of brain metastases negatively impact survival of patients with typical carcinoids but not in those with the other histological subtypes included in this study. Staging MRI should be strongly considered at diagnosis in patients with bronchopulmonary NE tumors, due to the sizable proportion of these patients presenting with brain metastases and also due to its prognostic value in a subset of this population. [Table: see text]

e20057 Background: T-cell lymphomas (TCL) are a heterogeneous group of rare, but aggressive non-Hodgkin lymphomas. CD4+ and CD8+ T-cell function plays a vital role in the immunologic response to P.jirovecii infection. Our study aims to define the prevalence of Pneumocystis jirovecii pneumonia (PJP) in HIV-uninfected TCL patients. Methods: All patients at Mayo Clinic, Rochester MN diagnosed with TCL and a positive Pneumocystis PCR assay from either bronchoalveolar lavage (BAL) fluid or other respiratory specimens were identified from March 2005 until November 2019. Patients with TCL and a diagnosis of PJP made outside of our medical center were identified through Advanced Cohort Explorer, a query building tool. Results: A total of 922 patients with TCL were identified, and only 14 cases (1.5%) had confirmed PJP. In confirmed PJP cases, the median age of TCL diagnosis was 62 years (IQR 51-70 years), 79% were male, and the median number of chemotherapy lines was 1.5 (IQR of 1-3). Half of the cases (6/12) received CHOP as first-line of therapy, followed by CHOEP (25%, 3/12). The median time to PJP diagnosis relative to chemotherapy was 18 days (IQR 14-27 days). Peripheral TCL, not otherwise specified was the most common TCL, followed by angioimmunoblastic TCL, and CD30+ T-cell lymphoproliferative disorders (64%, 29% and 7%, respectively). The primary specimen type sampled for PJP diagnosis was BAL fluid (n = 9, 64%), followed by sputum (n = 3, 22%), induced sputum (n = 1, 7%), and transbronchial lung biopsy (n = 1, 7%). Three patients had a prior autologous stem cell transplant (ASCT), and all three cases had relapsed TCL one year after ASCT. 77% of cases received oral prednisone equivalents (median dose of 25 mg, IQR 20-40 mg) 30 days prior to PJP diagnosis. Two patients developed PJP despite anti- Pneumocystis prophylaxis with aerosolized pentamidine. At the time of PJP diagnosis, most patients had lymphopenia (88%, 8/9), and CD4+ T-cells measurement was obtained only in one patient (CD4+ of 100 cells/mL). 71% of the cases were treated with trimethoprim/sulfamethoxazole (TMP/SMX). After the initial PJP episode, 36% of the cases were transitioned to TMP/SMX for secondary prophylaxis. All cause 30-day and 90-day mortality was 7% and 29%, respectively. Mortality attributed to PJP was 7% (n = 1). Conclusions: In our TCL cohort, the occurrence of PJP was low. Primary prophylaxis should be individualized in this population.

8046 Background: Patients (pts) with relapsed iNHL have limited standard treatment options. The immunomodulatory agent lenalidomide shows enhanced activity with rituximab (ie, R2), which recently reported 39.4-mo median PFS in R/R iNHL pts (AUGMENT; J Clin Oncol. 2019;37:1188). Methods: MAGNIFY is a multicenter, phase IIIb trial in pts with R/R FL gr1-3a, MZL, or MCL (NCT01996865) exploring optimal lenalidomide duration. Lenalidomide 20 mg/d, d1-21/28 + rituximab 375 mg/m2/wk c1 and then q8wk c3+ (R2) are given for 12c followed by 1:1 randomization in pts with SD, PR, or CR to R2 vs rituximab maintenance for 18 mo. Data presented here focus on induction R2 in efficacy-evaluable FL and MZL pts (MCL not included) receiving ≥ 1 treatment with baseline/post-baseline assessments to analyze the primary end point of ORR by 1999 IWG criteria. Results: As of June 16, 2019, 393 pts (81% FL gr1-3a; 19% MZL) were enrolled with a median follow up of 23.7 mo (range, 0.6-57.8) for censored pts (n = 335). Median age was 66 y (range, 35-91), 83% had stage III/IV disease, with a median of 2 prior therapies (95% prior rituximab-containing). ORR was 69% with 40% CR/CRu (Table). Median DOR was 39.0 mo, and median PFS was 40.1 mo. 199 pts (51%) have completed 12c of R2, and 188 (48%) have been randomized and entered maintenance. 139 pts (35%) prematurely discontinued both lenalidomide and rituximab, primarily due to AEs (n = 52, 13%) or PD (n = 45, 11%). Most common all-grade AEs were 48% fatigue, 43% neutropenia, 36% diarrhea, 31% nausea, and 30% constipation. Grade 3/4 AE neutropenia was 36% (9 pts [2%] had febrile neutropenia); all other grade 3/4 AEs occurred in < 7% of pts. Conclusions: R2 is active with a tolerable safety profile in pts with R/R FL and MZL, including rituximab-refractory, double-refractory, and early relapse pts. Clinical trial information: NCT01996865 . [Table: see text]

e19088 Background: Significant disparities in the stage at diagnosis and survival outcomes exist between various groups diagnosed with hepatocellular carcinoma (HCC) based on sex, race, insurance coverage, and marital status. Previously published data shows disparities more in patients who are African-American, Asian and low income. Little data has been published on factors that influence timeliness to treatment initiation in patients diagnosed with HCC. Methods: Retrospective analysis was performed on 96,586 patients diagnosed with HCC from 2004-2014 using data in the National Cancer Database (NCDB). Time to treatment was divided into two categories: ≤40 days (early, n = 66322) and > 40 days (late, n = 30264). We carried out univariate and multivariate analyses to compare demographic, clinical, treatment, and facility-related factors influencing the timeliness of treatment initiation in HCC. Results: Univariate analysis revealed a significant difference in time to treatment initiation based on age, race, income, insurance status, type of area, geographic region, type of facility, and cancer stage (P < 0.001). Multivariate analysis showed that household income < $30,000/year, Pacific region, urban area of residence, black race, age 70-79 years old or ≥80 years old, academic centers, stage II disease and medicaid insurance were all factors with longer time to treatment initiation. Discussion: HCC is the sixth most common cancer and the second leading cause of cancer mortality worldwide. The 5-year relative survival for localized, regional, and distant stages are 32.6%, 10.8% and 2.4% respectively. In our results we noted significant disparities in time to treatment with respect to various socioeconomic factors. These results are comparable to that reported in other cancer types. Further subgroup analysis of our data shows 2581 patients who received their first treatment after 200 days. In a similar study done in Taiwan, those treated more than 181 days and 61–180 days after diagnosis had a 1.68 and a 1.39 increased risk of death respectively, which were statistically significant. Many factors contribute to delayed treatment, some of which are difficult to circumvent, however where possible efforts should be made to overcome these. Conclusions: Various socioeconomic factors were found to affect the time to treatment initiation in HCC patients. The next step would be to strategically implement policies and practices to address these factors.

6040 Background: FRα is overexpressed on > 90% of high-grade EOC. We conducted a randomized double-blind multicenter phase II clinical trial to evaluate the safety and efficacy of TPIV200 (a multi-epitope FRα peptide vaccine admixed with GM-CSF adjuvant) versus GM-CSF alone as a control in patients with stage III-IV high-grade platinum-sensitive epithelial ovarian, fallopian tube, or primary peritoneal carcinoma in first complete or partial remission, irrespective of baseline level of FRα expression. Methods: Patients with stage III-IV high-grade serous, high-grade endometrioid, carcinosarcoma or poorly differentiated EOC who had previously completed standard upfront therapy without evidence of disease progression and who were within a year of last platinum were randomized 1:1 to intradermal vaccination of TPIV200 versus intradermal GM-CSF alone. The vaccination period included 6 administrations of the study drug at 4-week intervals. Up to 6 booster vaccinations at 12-week intervals were permitted for patients who did not have disease progression. AEs were assessed using CTCAE. Tumor response was assessed via RECIST every 12 weeks. The primary endpoint, progression free survival (PFS), was calculated from date of first vaccination to the date of progression, death or study termination. Results: Of 120 patients randomized, 63 (53%) were treated on the TPIV200 arm. The median age at study entry was 63 years (range 37-88). AEs were generally mild. Injection site reaction was more frequent in the TPIV200 (63%) versus GM-CSF arm (39%). The other most common AEs, abdominal pain (25%) and fatigue (23%), were comparable in both arms. At study termination with a median follow-up of 15.2 months (range: 1.2-28.3 months), 68 of 119 intention-to-treat patients had progressed (55% in the TPIV200 arm and 59% in the GM-CSF arm). The median PFS was 11.1 months (95% CI: 8.3-16.6 months) and there was no statistically significant difference in median PFS between the arms (10.9 months with TPIV200 versus 11.1 months with GM-CSF, HR = 0.85 [upper 90% CI = 1.17]). Conclusions: Although TPIV200 had a manageable safety profile, the study was terminated for futility after the planned interim analysis. Future development of FRα-targeted therapy will likely focus on the careful selection of patients whose cancers show high FRα expression. Clinical trial information: NCT02978222.

6016 Background: The role of HIPEC for recurrent EOC is not well defined. The aim of this phase II study was to determine the proportion of pts without evidence of disease progression at 24 months post SCS +/- intraoperative carboplatin HIPEC. Methods: After SCS to ≤ 0.5 cm residual visible disease pts were intraoperatively randomized to carboplatin HIPEC (800mg/m2 for 90 minutes) or no HIPEC. The HIPEC arm received 5 additional and the standard arm received 6 postoperative cycles of IV platinum-based chemotherapy without maintenance treatment. Based on an exact binomial single stage “pick the winner” design, each arm is considered “winner” if ≥ 17/49 pts are without evidence of disease progression at 24 months post SCS. Secondary objectives include postoperative grade ≥ 3 toxicity and complications within 4 weeks post SCS, and pharmacokinetics of carboplatin HIPEC. Results: Of 98 pts, 49 (50%) were randomized to the HIPEC arm. The arms were well balanced for age, stage, histology, BRCA mutation status, prior chemotherapy, and disease-free interval. Complete gross SCS was achieved in 94% of the standard and 82% of the HIPEC arm (p = 0.12). Bowel resection was performed more frequently in the standard (65%) compared to the HIPEC arm (37%; p = 0.008). Median operative time was shorter in the standard (296 minutes) compared to the HIPEC arm (475 minutes; p < 0.001). There was no perioperative mortality and no difference in use of ostomies, length of stay or postoperative toxicity. At a median follow-up of 27.7 months (range: 8.8-81.8 months) 70 of 98 pts progressed and 26 died with a median progression free survival (PFS) of 14.3 months (12.1-16 months) and a median overall survival (OS) of 55.2 months (47.7-not reached). At 24 months post SCS 32 pts progressed within 24 months in the standard versus 35 in the HIPEC arm. There was no statistically significant difference in median PFS (15.4 vs 12.3 months, p = 0.173) or median OS (69.2 vs 53.1 months, p = 0.317) between arms. These are preliminary efficacy estimates as 83/98 pts have a minimum of 24 months follow-up. Conclusions: The HIPEC arm did not reach the predefined “winner” endpoint; the standard arm is still undetermined as 6 pts did not reach 24 months follow-up. No perioperative mortality, and no increased perioperative morbidity or toxicity was seen with HIPEC. SCS with carboplatin HIPEC followed by 5 cycles of platinum-based chemotherapy was not superior to SCS without HIPEC followed by 6 cycles of platinum-based chemotherapy. Clinical trial information: NCT01767675.

4541 Background: Anti-VEGFR2 therapy (ramucirumab/paclitaxel [RAM/TAX]) and ICI are approved as 2nd- and 3rd-line therapy (Tx), respectively, for pts with mGEA. We unexpectedly saw durable responses in 2 pts on RAM/TAX after progression on an ICI trial (KN-059; PMID 29674442). We performed a pilot to examine the clinical activity of ICI followed by RAM/TAX. Then we retrospectively compared the outcomes of pts who received this serial Tx to pts who received RAM/TAX without prior ICI. Methods: All pts with mGEA at Mayo Clinic who received RAM/TAX (2014-19) were included (N = 87). Outcomes were best objective response rate (ORR: complete [CR] or partial response) per RECIST1.1, progression-free survival (PFS), duration of response (DOR), and overall survival (OS). Chi square and multivariate (MV) logistic and Cox regression were used. Results: 15 consecutive pts with measurable mGEA received ICI immediately followed by RAM/TAX after irRECIST progression. Most pts (95%) did not respond to ICI. Yet on RAM/TAX, 100% (15/15) had tumor reduction (range -8% to -100%) with an ORR of 73% (11/15), including 3 CRs. In these pts (who received ICI followed by RAMTAX), PFS on RAMTAX was longer than on last chemotherapy before ICI (12.3 vs 3.0 m, P < .001). Outcomes on RAM/TAX in these pts were significantly better than in pts who received RAM/TAX alone (see Table). Associations were strengthened after adjusting for total lines of Tx, line of Tx of RAM/TAX, age, and ECOG PS. Exploratory analysis of paired tumor biopsies collected pre-ICI and on RAM/TAX in a small subset revealed that the frequency of intratumoral immunosuppressive FOXP3+ Tregs decreased on RAM/TAX, whereas the frequency of antitumor CD8+ T cells was preserved. Conclusions: RAM/TAX immediately preceded by ICI was associated with significantly higher OS, ORR, and DOR than RAM/TAX alone, suggesting ICI may enhance efficacy of subsequent anti-VEGFR/taxane therapy. This novel sequence of therapy will be tested prospectively in a new randomized phase 2 trial (NCT04069273). [Table: see text]

4108 Background: Circulating tumor DNA (ctDNA) testing can be used for the assessment of molecular residual disease (MRD) in patients with early-stage or advanced colorectal cancer (CRC). Prospective evaluation of this methodology in clinical practice has been limited to-date. Methods: A personalized and tumor-informed multiplex PCR assay (Signatera 16-plex bespoke mPCR NGS assay) was used for the detection and quantification of ctDNA for MRD assessment. We analyze and present results from an ongoing early adopter program of ctDNA testing across the spectrum of CRC management. Results: Here we present a total of 250 patients with colon (n=200), rectal (n=40), and other lower gastrointestinal cancers (n =10; anal, appendiceal, small bowel). MRD positivity rates and ctDNA quantification (mean tumor molecules/mL) are shown in Table. ctDNA detection was significantly associated with stage of disease (p<0.0001 Chi-square: 70.33). Additionally, in patients with radiologically measurable active metastatic disease, ctDNA detection rate was 100%. On the contrary, patients with advanced/metastatic disease who had partial response to treatment or no evidence of disease (NED) showed 28.5% and 19.2% of ctDNA-positivity, respectively. Conclusions: This is the first large, real-world study reporting on the results from a clinically validated MRD assay. For the first time we delineate MRD rates and quantify ctDNA concentration in patients with early-stage and advanced CRC. Furthermore, we provide an initial readout that effective ongoing treatment in patients with CRC may be correlated with ctDNA clearance. Ongoing analysis expanded to a cohort of 1200 clinical cases including correlation with genomic and serial testing will be presented. [Table: see text]

e13681 Background: Cell-free tumor DNA or circulating tumor DNA tests are increasingly used in clinical care to detect somatic mutations from solid tumors. However, data on laboratory performance characteristics using standardized samples is limited. Methods: Well-characterized reference materials were used for the College of American Pathologists (CAP) cell-free tumor DNA proficiency testing surveys, which consisted of stabilized DNA fragmented to simulate cell-free DNA in a synthetic plasma matrix. For the 2018A, 2018B, 2019A and 2019B surveys, laboratories tested for hotspot mutations (single and dinucleotide sequence changes) in EGFR, BRAF, KRAS, NRAS, and IDH1 at variant allele fractions ranging from 0.1% - 1.0%. As per CAP proficiency testing standards, results were scored according to the known mutation(s) engineered at designated variant allele fractions in each PT sample. Nine laboratories were excluded from analysis because they provided incomplete results. Statistical significance was calculated using a multivariate logistic regression model. Results: In 2018 and 2019, 101 laboratories submitted survey results for at least one proficiency testing mailing. There were 5088 total proficiency testing responses for EGFR, BRAF, KRAS, NRAS, and IDH1 mutations across 12 different samples. For the 3585 responses submitted for BRAF, KRAS, NRAS, and IDH1, sensitivity ranged from 94.6 – 100%, while specificity exceeded 99%. There were no significant differences in performance between analytical methodologies for BRAF, KRAS, NRAS, and IDH1 mutations. Performance characteristics for EGFR mutations among the 1503 responses showed a combined sensitivity of 87.1% and specificity of 98.7%. For laboratories detecting mutations in EGFR, next-generation sequencing methods exhibited a sensitivity (true positivity) of 95.7% while the sensitivity of non-NGS methods was lower at 81.7% ( P= 0.02). Conclusions: These findings demonstrate high sensitivity and specificity for clinical laboratories performing cell-free tumor DNA tests. For EGFR mutations, NGS outperformed non-NGS methods. These data suggest excellent overall agreement among laboratories performing clinical cell-free tumor DNA tests. Further investigation across variant allele fractions and additional variant types is warranted.