Improvement In Progression-free Survival Research Articles

Abstract PO4-19-11: A Multicenter, Phase Ib/II Study of Abemaciclib in Combination with Bicalutamide for Androgen Receptor-positive, HER2-negative Metastatic Breast Cancer

Abstract Background The androgen receptor (AR) is expressed in approximately 30% of breast cancers. Phase I and II trials of bicalutamide in HR-negative and enzalutamide in both triple negative breast cancer (TNBC) and hormone receptor (HR) positive populations have shown safety and favorable clinical benefit rates (CBR). Additionally, cell cycle (CC) inhibitors, such as abemaciclib, have demonstrated improved progression free survival (PFS) for patients with HR-positive metastatic breast cancer (MBC) in combination with ET in the first line and subsequent lines of therapy. A preclinical study showed that anti-androgen therapies enhanced CKD4/6 induced cytostatic effect in AR-positive TNBC cell lines. We performed a retrospective, institutional study evaluating metastatic HR+ tumor samples with immunohistochemistry (IHC) from patients treated with CDK4/6 inhibitor, palbociclib. We found a statistically significant increase in event free survival (EFS) for those that had any expression of AR (>0%, median EFS 19 months vs 5 months, HR 0.26, p=0.01). Additionally, AR expression was associated with intact phosphorylated retinoblastoma (Rb) expression (100%, P=0.02), which may represent a mechanism by which CC inhibition is effective in AR+ MBC. Trial Design NCT 05095207 is an ongoing, Phase Ib/II, open label, multi-center study. The primary objective for the phase I portion is to determine the recommended phase II dose (RP2D) of abemaciclib in combination with bicalutamide. The primary objective for the phase II portion is to determine the disease control rate (DCR) at 6-month treatment with abemaciclib and bicalutamide. Patients with HER2-negative MBC who are AR+ (IHC >1%) are eligible. HR-positive participants must have had one prior line of ET in the metastatic setting and no more than 2 prior lines of cytotoxic chemotherapy. HR-negative participants may have had up to 4 prior lines of cytotoxic chemotherapy. In the Phase I portion, up to 12 patients are given abemaciclib 100 mg oral, twice daily on days 1 to 28 and bicalutamide 150 mg oral, daily on days 1 to 28. If there is no toxicity after cycle 1 for the first 3 patients, the dose of abemaciclib will increase to 150 mg twice daily. However, if there is a dose limiting toxicity (DLT) within the first cycle (28 days) of therapy, the dose will decrease to 50 mg twice daily. In the Phase II portion, 51 patients will receive abemaciclib at the RP2D twice daily in addition to bicalutamide 150 mg daily on days 1 to 28. The estimated study duration is 36 months. The drugs will be administered until disease progression or unacceptable toxicity. The primary end points include the DLT and the RP2D for abemaciclib administered with bicalutamide and the DCR at 6 months. The secondary end points include the frequency of adverse effects, the DCR stratified by HR status, and PFS. Exploratory endpoints are to determine whether Ki67, cyclin D1, p16, and phosphorylated Rb expression at baseline are predictors of response to abemaciclib and to determine potential mechanisms for resistance to treatment. For Phase Ib, we will utilize the Bayesian optimal interval (BOIN) design, the RP2D will be selected as the dose closest to the target toxicity rate of 0.3. The observed DLT rate at the current dose is ≤ 0.236, the next cohort will be treated at the next higher dose level, if it is ≥ 0.359 the next cohort will be treated with the next lower dose level. For Phase II, we will assess the DCR using a Simon 2 stage optimal design. If among the 46 evaluable patients, 12 or fewer achieve disease control, the treatment will be rejected, however if 13 or more have disease control, the treatment will be considered worthy for further study. We define inactivity as DCR of 0.20 and activity as DCR of 0.35. To date, the study has recruited 21 participants, the goal accrual is 60 patients. Citation Format: Nicole Casasanta, Chrystal Landry, Theresa Shao, Paula Klein, Julie Fasano, Aarti Bhardwaj, Natalie Berger, Erin Moshier, Gargi Atul Joshi, Rita Vaccaro, Joseph Sparano, Amy Tiersten. A Multicenter, Phase Ib/II Study of Abemaciclib in Combination with Bicalutamide for Androgen Receptor-positive, HER2-negative Metastatic Breast Cancer [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO4-19-11.

Impact of prior treatment on selinexor, bortezomib, dexamethasone outcomes in patients with relapsed/refractory multiple myeloma: Extended follow-up subgroup analysis of the BOSTON trial.

To analyze the impact of prior therapies on outcomes with selinexor, bortezomib, and dexamethasone (SVd) versus bortezomib and dexamethasone (Vd) in 402 patients with relapsed/refractory multiple myeloma (RRMM) in the phase 3 BOSTON trial. Post hoc analysis of progression-free survival (PFS), overall survival (OS), and safety for lenalidomide-refractory, proteasome inhibitor (PI)-naïve, bortezomib-naïve, and one prior line of therapy (1LOT) patient subgroups. At a median follow-up of over 28 months, clinically meaningful improvements in PFS were noted across all groups with SVd. The median SVd PFS was longer in all subgroups (lenalidomide-refractory: 10.2 vs. 7.1 months, PI-naïve: 29.5 vs. 9.7; bortezomib-naïve: 29.5 vs. 9.7; 1LOT: 21.0 vs. 10.7; p < .05). The lenalidomide-refractory subgroup had longer OS with SVd (26.7 vs. 18.6 months; HR 0.53; p = .015). In all subgroups, overall response and ≥very good partial response rates were higher with SVd. The manageable safety profile of SVd was similar to the overall patient population. With over 2 years of follow-up, these clinically meaningful outcomes further support the use of SVd in patients who are lenalidomide-refractory, PI-naïve, bortezomib-naïve, or who received 1LOT (including a monoclonal antibody) and underscore the observed synergy between selinexor and bortezomib.

Breakthrough Therapy Cancer Drugs and Indications With FDA Approval: Development Time, Innovation, Trials, Clinical Benefit, Epidemiology, and Price.

The breakthrough therapy designation (BTD) facilitates the development of drugs with a large preliminary benefit in treating serious or life-threatening diseases. This study analyzes the FDA approval, trials, benefits, unmet needs, and pricing of breakthrough and nonbreakthrough therapy cancer drugs and indications. We analyzed 355 cancer indications with FDA approval (2012-2022). Breakthrough and nonbreakthrough indications were compared regarding their FDA approval, innovativeness, clinical trials, epidemiology, and price. Data were extracted from FDA labels, the Global Burden of Disease study, and the Centers for Medicare & Medicaid Services. Hazard ratios (HRs) for overall survival (OS), progression-free survival (PFS), and relative risk (RR) of tumor response were meta-analyzed across randomized controlled trials. Objective response rates (ORRs) were meta-analyzed for single-arm trials. We identified 137 breakthrough and 218 nonbreakthrough cancer indications. The median clinical development time was 3.2 years shorter for breakthrough drugs than for nonbreakthrough drugs (5.6 vs 8.8 years; P=.002). The BTD was more frequently granted to biomarker-directed indications (46% vs 34%; P=.025) supported by smaller trials (median, 149 vs 326 patients; P<.001) of single-arm (53% vs 27%; P<.001) and phase I or II design (61% vs 31%; P<.001). Breakthrough indications offered a greater OS (HR, 0.69 vs 0.74; P=.031) and tumor response (RR, 1.48 vs 1.32; P=.006; ORR, 52% vs 40%; P=.004), but not a PFS benefit (HR, 0.53 vs 0.58; P=.212). Median improvements in OS (4.8 vs 3.2 months; P=.002) and PFS (5.4 vs 3.3 months; P=.005) but not duration of response (8.7 vs 4.7 months; P=.245) were higher for breakthrough than for nonbreakthrough indications. The BTD was more frequently granted to first-in-class drugs (42% vs 28%; P=.001) and first-in-indication treatments (43% vs 29%; P<.001). There were no differences in treatment and epidemiologic characteristics between breakthrough and nonbreakthrough drugs. Breakthrough drugs were more expensive than nonbreakthrough drugs (mean monthly price, $38,971 vs $22,591; P=.0592). The BTD expedites patient access to effective and innovative, but also expensive, new cancer drugs and indications.

Efficacy and safety of anlotinib in combination with immune checkpoint inhibitors or not as advanced non-small cell lung cancer treatment: a systematic review and network meta-analysis.

Non-small cell lung cancer (NSCLC) remains a leading cause of cancer mortality. Combined anlotinib and immune checkpoint inhibitors (ICIs) therapy may have synergistic antitumor effects in NSCLC. This study aimed to comparing the efficacy and safety of anlotinib and ICIs treatment, monotherapy and combination in NSCLC. We performed a systematic review and network meta-analysis of 14 studies involving 4,308 NSCLC patients across four regimens: anlotinib, ICIs, anlotinib plus ICIs, and placebo. Efficacy outcomes were progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and disease control rate (DCR). Safety outcomes included treatment-related adverse events (TRAEs), TRAE grade three or higher (TRAE ≥3). Analyses were performed in RevMan 5.3 and R 3.5.1 (gemtc package). P<0.05 or effect estimate with 95% confidence interval (CI) that did not include 1 indicated statistical significance. Fourteen publications involving 4,308 patients across four treatment regimens (anlotinib, ICIs, anlotinib plus ICIs, placebo) were included. For PFS, network meta-analysis showed all three interventions significantly improved PFS versus placebo. Anlotinib plus ICIs demonstrated the greatest PFS improvement [hazard ratio (HR) =0.24; 95% CI: 0.14, 0.36], followed by anlotinib (HR =0.37; 95% CI: 0.23, 0.58), and ICIs (HR =0.43; 95% CI: 0.27, 0.67). For OS, compared to placebo, anlotinib plus ICIs showed the greatest OS improvement (HR =0.52; 95% CI: 0.33, 0.74), followed by anlotinib (HR =0.66; 95% CI: 0.47, 0.95), and ICIs (HR =0.72; 95% CI: 0.54, 0.97). For ORR, anlotinib plus ICIs demonstrated the greatest improvement versus placebo [odds ratio (OR) =5.29; 95% CI: 3.32, 8.58], followed by anlotinib (OR =4.38; 95% CI: 2.42, 8.19), and ICIs (OR =2.17; 95% CI: 1.65, 2.89). For DCR, anlotinib plus ICIs showed the greatest improvement versus placebo (OR =13.32; 95% CI: 4.99, 45.09), followed by anlotinib (OR =5.56; 95% CI: 2.17, 14.38), and ICIs (OR =3.46; 95% CI: 1.29, 10.85). Compared to placebo, anlotinib was associated with the highest risk of TRAEs (OR =3.67, 95% CI: 1.12, 15.77), followed by ICIs (OR =1.83; 95% CI: 1.26, 2.69). Due to lack of data on anlotinib plus ICIs, no comparison was conducted. For grade ≥3 TRAEs, compared to placebo, anlotinib increased the risk (OR =3.67; 95% CI: 1.12, 15.77), while anlotinib plus ICIs (OR =2.45; 95% CI: 0.51, 11.6) and ICIs (OR =1.29; 95% CI: 0.33, 4.38) did not increase the risk. Anlotinib combined with ICIs demonstrates improved efficacy over monotherapy for NSCLC treatment, without increased adverse events.

Maintenance Therapy for CD20+ Indolent Lymphoma: Who Should Receive Maintenance?

Maintenance rituximab (MR) has been a mainstay of treatment in Canada for CD20‑positive indolent lymphoma for two decades. The adoption of MR into clinical practice occurred after the publication of the EORTC 20981 trial. This trial showed a significant improvement in progression free survival (PFS) with two years of MR versus observation after induction therapy with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) or rituximab with cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) in patients with relapsed follicular lymphoma (FL). The use of MR was broadly extended to include its use in the front‑line setting, following any R-containing inductions and including all CD20-positive indolent lymphoma histologies. Automatic recommendations for MR became the standard practice for most patients. Given the recent changes to standard induction regimens in some indications, and with heightened concerns about infectious complications during B-cell depleting therapy, the recommendation for the use of MR should no longer be considered automatic. This review offers a balanced perspective of the evidence for MR.

Efficacy and safety of novel immune checkpoint inhibitor-based combinations versus chemotherapy as first-line treatment for patients with extensive-stage small cell lung cancer: A network meta-analysis.

Patients with extensive-stage small cell lung cancer (ES-SCLC) have an exceptionally poor prognosis and immune checkpoint inhibitors (ICIs) combined with etoposide-platinum is recommended as standard first-line therapy. However, which combination pattern is the best still remains unknown. This network meta-analysis was performed to compare the efficacy and safety of currently available patterns including an antiangiogenic agent containing regimen and probed into the most appropriate therapy for patients. Hazard ratios (HRs) and odds ratios (ORs) were generated using R software. The outcomes of overall survival (OS), progression-free survival (PFS), objective response rate (ORR), and adverse events of grade 3 or higher (grade ≥ 3 adverse events [AEs]) were analyzed. A total of 10 randomized controlled trials (RCTs) involving 5544 patients were included for analysis. Drug combination patterns included adebrelimab, atezolizumab, durvalumab, durvalumab plus tremelimumab, ipilimumab, pembrolizumab, serplulimab, benmelstobart plus anlotinib, tislelizumab, tiragolumab plus atezolizumab and toripalimab in combination with chemotherapy. The novel antiangiogenic agent containing regimen benmelstobart + anlotinib + chemotherapy showed the highest possibility to present the best PFS and OS versus chemotherapy. Compared with ICI plus chemotherapy, it also achieved significantly better PFS and presented a tendency of OS benefit. As for safety and toxicity, patients treated with benmelstobart + anlotinib + chemotherapy and durvalumab + tremelimumab + chemotherapy suffered a higher likelihood of more grade ≥ 3 AEs without unexpected AEs. PD-1/PD-L1 inhibitors-based combinations are associated with significant improvement in both PFS and OS for treatment-naïve ES-SCLC patients. Benmelstobart plus anlotinib with chemotherapy (CT) yielded better survival benefit versus CT alone or other ICIs + CT with caution for more adverse effects along with the addition of an antiangiogenic agent.

Combination of metronomic capecitabine and letrozole in metastatic hormone receptor positive, HER2 negative breast cancer: a randomized phase II trial

First line endocrine therapy is the gold standard for advanced estrogen receptor positive, human epidermal growth factor receptor 2 negative breast cancer. Adding CDK4/6 inhibitors has improved progression free survival. Metronomic Capecitabine has proven to be safe to combine with endocrine therapy with promising efficacy. We conducted a phase II randomized, open label, single centre clinical trial on patients with metastatic ER positive and HER 2 negative breast cancer. Eligible patients were randomized (1:1) to arm A: metronomic dose of capecitabine (500 mg/m2 BID) combined with letrozole (2.5 mg OD) or arm B: letrozole single agent. The primary endpoint was progression free survival. The study was terminated early due to poor accrual and 60 eligible patients out of the planned 204 were randomized. This clinical trial is registered on ClinicalTrials.gov (MD-127-2019, NCT04571437). Between February 2019 and April 2022, 60 patients were randomized. This is the first report of the study, after a median follow-up of 18.6 months. The median age at diagnosis was 47 years with only 41.7% of patients post-menopausal. Half of our patients had bone-only disease, 45% had visceral metastasis (liver and lung) and 63% presented with endocrine sensitive disease. The estimated median PFS for the whole population was 16.2 months. Median PFS for capecitabine arm was 17.7 months versus 14.6 months for letrozole alone (p = 0.078). Overall response rate was 70% for capecitabine/letrozole arm and 56.6% for letrozole only. Clinical benefit rate was 90% in the capecitabine/letrozole arm versus 73.3% in the letrozole arm. Overall survival data is still immature after this short follow up duration. Adverse event assessment showed acceptable all grade and high grade toxicity profile consistent with the established adverse events of both capecitabine and letrozole. Anaemia (28.3%) and hand & foot syndrome (43.8%) were significantly more common in the capecitabine/letrozole arm. Capecitabine combined with letrozole have showed a trend towards improvement in progression free survival with potential more benefit to certain sub-groups and the combination showed acceptable safety profile consistent with the established known safety profile of both letrozole and capecitabine.

SABR-Dual: a phase II/III trial of two-fraction versus five-fraction stereotactic radiotherapy for localized low- and favorable intermediate-risk prostate cancer.

Dose-escalated radiotherapy is known to improve progression free survival in patients with localized prostate cancer, and recent advances have led to the standardization of ultrahypofractionated stereotactic ablative radiotherapy (SABR) delivered in just 5-fractions. Based on the known effectiveness of the accepted though invasive 2-fraction treatment method of high-dose-rate brachytherapy and given the ubiquity of prostate cancer, a further reduction in the number of treatments of external-beam SABR is possible. This study aims to evaluate the safety, efficacy, and non-inferiority of generalizable 2-fraction SABR compared to the current 5-fraction regimen. 502 patients will be enrolled on this phase II/III randomized control trial. Eligible patients will have previously untreated low- or favorable intermediate-risk adenocarcinoma of the prostate. Patients will be randomized between standard SABR of 40Gy in 5 fractions given every-other-day and 27Gy in 2 fractions at least two days apart but completing within seven days. MRI-based planning, radiopaque hydrogel spacer insertion, and fiducial marker placement are required, and SABR will be delivered on either a standard CT-guided linear accelerator or MR-LINAC. The primary endpoint will be freedom from disease progression, with additional secondary clinical, toxicity, and quality of life endpoints. This study will be the largest prospective randomized trial, adequately powered to demonstrate non-inferiority, comparing 2-fraction SABR to standard 5-fraction SABR for localized prostate cancer. As the protocol does not obligate use of an MRI-LINAC or other adaptive technologies, results will be broadly generalizable to the wider community. This trial is registered on Clinicaltrials.gov: ClinicalTrials.gov Identifier: NCT06027892.

Abstract CT252: Nicotinamide in combination with EGFR-TKIs for the treatment of stage IV lung adenocarcinoma with EGFR mutations: A randomized double-blind (Phase IIb) trial

Abstract Background: RUNX3 is a tumor suppressor gene, which is inactivated in approximately 70% of lung adenocarcinomas. Nicotinamide, a sirtuin inhibitor, has demonstrated potential in re-activating epigenetically silenced RUNX3 in cancer cells. This study assessed the therapeutic benefits of combining nicotinamide with first-generation EGFR-TKIs for patients with stage IV lung cancer carrying EGFR mutations. Patients and Methods: We assessed the impact of nicotinamide on carcinogen-induced lung adenocarcinomas in mice and observed that nicotinamide increased RUNX3 levels and inhibited lung cancer growth. Subsequently, 110 consecutive patients with stage IV lung cancer who had EGFR mutations were recruited: 70 females (63.6%) and 84 never-smokers (76.4%). The patients were randomly assigned to receive either nicotinamide (1 g/day, n = 55) or placebo (n = 55). The primary and secondary endpoints were progression-free survival (PFS) and overall survival (OS), respectively. Results: After a median follow-up of 54.3 months, the nicotinamide group exhibited a median PFS of 12.7 months (95% CI, 10.4-18.3), while the placebo group had a PFS of 10.9 months (9.0-13.2; p = 0.2). The median OS was similar in the two groups (31.0 months with nicotinamide vs. 29.4 months with placebo; p = 0.2). Notably, subgroup analyses revealed a significant reduction in mortality risk for females (p = 0.01) and never-smokers (p = 0.03) treated with nicotinamide. Conclusion: The addition of nicotinamide with EGFR-TKIs demonstrated potential improvements in PFS and OS, with notable survival benefits for female patients and those who had never smoked. (ClinicalTrials.gov Identifier: NCT02416739) Citation Format: Cheol-Kyu Park, Hyung-Joo Oh, Suk-Chul Bae, In-Jae Oh, Kyoung-Mi Jung, Da-Mi Kim, Jung-Won Lee, Chang Kyun Kang, Il Yeong Park, Young-Chul Kim. Nicotinamide in combination with EGFR-TKIs for the treatment of stage IV lung adenocarcinoma with EGFR mutations: A randomized double-blind (Phase IIb) trial [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr CT252.

XELOX (capecitabine plus oxaliplatin) plus bevacizumab (anti-VEGF-A antibody) with or without adoptive cell immunotherapy in the treatment of patients with previously untreated metastatic colorectal cancer: a multicenter, open-label, randomized, controlled, phase 3 trial

Fluoropyrimidine-based combination chemotherapy plus targeted therapy is the standard initial treatment for unresectable metastatic colorectal cancer (mCRC), but the prognosis remains poor. This phase 3 trial (ClinicalTrials.gov: NCT03950154) assessed the efficacy and adverse events (AEs) of the combination of PD-1 blockade-activated DC-CIK (PD1-T) cells with XELOX plus bevacizumab as a first-line therapy in patients with mCRC. A total of 202 participants were enrolled and randomly assigned in a 1:1 ratio to receive either first-line XELOX plus bevacizumab (the control group, n = 102) or the same regimen plus autologous PD1-T cell immunotherapy (the immunotherapy group, n = 100) every 21 days for up to 6 cycles, followed by maintenance treatment with capecitabine and bevacizumab. The main endpoint of the trial was progression-free survival (PFS). The median follow-up was 19.5 months. Median PFS was 14.8 months (95% CI, 11.6–18.0) for the immunotherapy group compared with 9.9 months (8.0–11.8) for the control group (hazard ratio [HR], 0.60 [95% CI, 0.40–0.88]; p = 0.009). Median overall survival (OS) was not reached for the immunotherapy group and 25.6 months (95% CI, 18.3–32.8) for the control group (HR, 0.57 [95% CI, 0.33–0.98]; p = 0.043). Grade 3 or higher AEs occurred in 20.0% of patients in the immunotherapy group and 23.5% in the control groups, with no toxicity-associated deaths reported. The addition of PD1-T cells to first-line XELOX plus bevacizumab demonstrates significant clinical improvement of PFS and OS with well tolerability in patients with previously untreated mCRC.

Efficacy of immune checkpoint inhibitors in advanced non-small cell lung cancer patients with KRAS mutations: A network meta-analysis.

Previous studies have shown that immune checkpoint inhibitors can improve the survival of patients with advanced non-small cell lung cancer with KRAS mutations; however, there is a lack of comparisons between treatment regimens associated with immune checkpoint inhibitors, and our study aims to compare several treatment parties to find a more effective treatment regimen. A comprehensive literature search was conducted across multiple databases, namely PubMed, Web of Science, Embase, and Cochrane Library, to identify relevant studies. The screened studies were thoroughly examined, and data were collected to establish a Bayesian framework. The study focused on two primary endpoints: overall survival (OS) and progression-free survival (PFS). Data analysis and graphical plotting using R software and Revman (version 5.3). It is worth mentioning that the study protocol was registered with the International Prospective Registry for Systematic Reviews, ensuring transparency and adherence to predetermined protocols (CRD42022379595). In total, our analysis included six RCTs involving 469 patients with KRAS mutations. Among these patients, 224 received chemotherapy, while 245 were treated with immune checkpoint inhibitors. Meta-analysis results showed that the addition of ICIs could significantly improve OS and PFS (0.69, 95% CI 0.55, 0.86; 0.57, 95% CI 0.42, 0.77). The results of the network meta-analysis showed that Pembrolizumab could improve OS (HR 0.42, 95% CI 0.22-0.80) and Pembrolizumab emerged as the most effective treatment option for enhancing OS in patients (SUCRA 65.03%). Additionally, pembrolizumab in combination with chemotherapy showed improvement in PFS (HR 0.47, 95% CI 0.29-0.76). Our analysis found that among advanced NSCLC patients with KRAS gene mutations, first-line treatment with pembrolizumab alone demonstrated greater efficacy. Similarly, second-line treatment with nivolumab alone was found to be more effective in this patient population. However, the sample size of this study was limited, Therefore, additional clinical data is necessary to validate this finding in subsequent research.

Six versus four or five cycles of first-line etoposide and platinum-based chemotherapy combined with thoracic radiotherapy in patients with limited-stage small-cell lung cancer: A propensity score-matched analysis of a prospective randomized trial.

The recommended treatment for limited-stage small-cell lung cancer (LS-SCLC) is a combination of thoracic radiotherapy (TRT) and etoposide plus cisplatin (EP) chemotherapy, typically administered over 4-6 cycles. Nonetheless, the optimal duration of chemotherapy is still not determined. This study aimed to compare the outcomes of patients with LS-SCLC who received either 6 cycles or 4-5 cycles of EP chemotherapy combined with TRT. In this retrospective analysis, we utilized data from our prior prospective trial to analyze the outcomes of 265 LS-SCLC patients who received 4-6 courses of EP combined with concurrent accelerated hyperfractionated TRT between 2002 and 2017. Patients were categorized into two groups depending on their number of chemotherapy cycles: 6 or 4-5 cycles. To assess overall survival (OS) and progression-free survival (PFS), we employed the Kaplan-Meier method after conducting propensity score matching (PSM). Among the 265 LS-SCLC patients, 60 (22.6%) received 6 cycles of EP chemotherapy, while 205 (77.4%) underwent 4-5 cycles. Following PSM (53 patients for each group), the patients in the 6 cycles group exhibited a significant improvement in OS and PFS in comparison to those in the 4-5 cycles group [median OS: 29.8 months (95% confidence interval [CI], 23.6-53.1 months) vs. 22.7 months (95% CI, 20.8-29.1 months), respectively, p = 0.019; median PFS: 17.9 months (95% CI, 13.7-30.5 months) vs. 12.0 months (95% CI, 9.8-14.2 months), respectively, p = 0.006]. The two-year and five-year OS rates were 60.38% and 29.87% in the 6 cycles group, whereas 47.17% and 15.72% in the 4-5 cycles group, respectively. Patients diagnosed with LS-SCLC who were treated with EP regimen chemotherapy combined with TRT exhibited notably enhanced survival when administered 6 cycles of chemotherapy, as compared to those who underwent only 4-5 cycles.

Abstract 6640: Zap! Irreversible electroporation in pancreatic cancer cells induces proinflammatory cell death and improves progression free survival

Abstract Pancreatic cancer is the third leading cause of cancer-related death due to its late diagnosis, few treatment options, and extremely low survival rates due to its immunosuppressive microenvironment. Irreversible electroporation (IRE),is a tumor non-thermal ablation technique that applies high-voltage electrical pulses to permeabilize the cell membrane that is irreversible and leads to necrotic cell death. IRE has had strong success in clinical trials nevertheless, little is known about the effect of IRE beyond the initiation of cell death in the tumor tissue. We hypothesize that IRE can not only induce cell death by membrane disruption to facilitate a proinflammatory microenvironment but also causes death via cell cycle arrest. We utilized in-vitro, and immunocompetent in-vivo murine models to investigate changes to pancreatic cancer and the tumor microenvironment. Our findings show that treating the cells with an increasing voltage of IRE induces more cell death. We observed cell cycle arrest in the G1 phase which may have been caused by DNA damage. There was upregulation of DNA damage repair machinery in the treated samples. Our histopathology data suggests increased necrosis on the tumor treated with IRE, as also PCR array analysis showed more proinflammatory cell death caused by pyroptosis. Finally, we demonstrated a reduction in the tumor size and a better survival rate aftertreatment. Our data suggest that Irreversible electroporation has a promising future in inducing proinflammatory type of cell death in the tumor and benefits increased patient survival. More investigation is needed to define ideal parameters for the electrical pulses and device development for tumor ablation in larger animals like porcine models. Citation Format: Manali Powar, Khan Mohammad Imran, Irving C. Allen, Rafael V. Davalos, Zaid Salamah, Kenneth Aycock, Rebecca M. Brock, Sheryl Coutermarsh-Ott, Katie Orr. Zap! Irreversible electroporation in pancreatic cancer cells induces proinflammatory cell death and improves progression free survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6640.

Abstract 3846: The obesity paradox in immune checkpoint blockade: A pan-tumor analysis

Abstract Background: Chronic systemic inflammation mediated by pro-inflammatory cytokines serves as a major mechanism by which obesity contributes to cancer development. Paradoxically, elevated body mass (BMI) has been associated with improved outcomes after treatment with immune checkpoint inhibitors (ICIs) in many tumor types. The interplay between cytokine response and obesity after ICIs is poorly understood. To characterize underlying mechanisms, we investigated cytokine profiles in relation to obesity and clinical outcomes in patients treated with ICIs. Methods: From June 2021 to October 2022, we enrolled and collected blood samples from patients with advanced or metastatic solid tumors who received ICIs as standard of care at Johns Hopkins. We calculated BMI using height and weight at treatment initiation, with BMI ≥30 obese and BMI &amp;lt;30 non-obese. Underweight patients (BMI &amp;lt;18.5) were excluded. The Bioplex 200 platform (Biorad, Hercules CA) was used to determine the plasma concentration of 37 cytokines at baseline and on-treatment, with the median cytokine value used to differentiate between high and low concentration. Results: Among 94 patients, 29 (31%) were obese and 65 (69%) were non-obese, with a significant difference in sex (Fisher’s exact test, p = 0.02), but no observed difference in age, race, cancer type, autoimmune disease, or presence of immune-related adverse events (irAE) based on BMI category; all the following hazard ratios (HR) are therefore adjusted for sex. Obese patients had improved progression free survival (PFS) (HR 0.41 [95% CI: 0.21-0.80], p=0.01) and overall survival (OS) (HR 0.16 [95% CI: 0.04-0.69], p=0.01). Eighty-six patients had cytokine data at baseline (range: eight days prior to day of initiation). Baseline IL-15 was significantly lower in obese patients (1.71 vs. 2.08, p=0.04), however, there was no difference in PFS (HR 1.49 [95% CI: 0.87-2.56], p=0.15) or OS (HR 1.22 [95% CI: 0.51-2.97], p=0.65) comparing low vs. high baseline IL-15. Eighty-two patients had cytokine data on-treatment (range: 21-349 days after initiation), with significantly lower levels of IL-6 (2.49 vs. 3.45, p=0.04), IL-8 (2.01 vs. 2.92, p=0.01), and IL-15 (1.70 vs. 1.81, p=0.01) in obese vs. non-obese patients, respectively. Low on-treatment IL-8 was associated with improved PFS (HR 0.52 [95% CI: 0.29-0.92], p=0.02) and OS (HR 0.17 [95% CI: 0.05-0.58], p&amp;lt;0.01), and low on-treatment IL-6 was associated with improved OS (0.25 [95% CI: 0.08-0.76], p=0.01). Conclusions: In a diverse, pan-tumor ICI cohort, we observed a positive relationship between obesity and clinical outcomes with ICIs, with no correlation between obesity and irAEs. We also observed lower on-treatment levels of IL-6 and IL-8 in patients with obesity and that low on-treatment levels of IL-6 and IL-8 correlated with improved survival, suggesting that IL-6 and IL-8 may serve as mediating factors for improved outcomes in obese patients treated with ICIs. Citation Format: Stephanie Leigh Alden, Soren Charmsaz, Madelena Brancati, Howard L. Li, Aanika Warner, Kabeer Munjal, Kathryn Howe, Sarah Mitchell, Ervin Griffin, Mari Nakazawa, Hua-Ling Tsai, Ludmila Danilova, Chris Thoburn, Jennifer Gizzi, Alexei Hernandez, Nicole E. Gross, Erin M. Coyne, Sarah M. Shin, Jennifer Durham, Maximilian F. Konig, Brian J. Christmas, Evan J. Lipson, Jarushka Naidoo, Laura C. Cappelli, Aliyah Pabani, Yasser Ged, Marina Baretti, Julie R. Brahmer, Jean Hoffman-Censits, Tanguy Y. Seiwert, Sanjay Bansal, Laura Tang, Elizabeth Jaffee, G Scott Chandler, Rajat Mohindra, Won Jin Ho, Mark Yarchoan, Chester Kao. The obesity paradox in immune checkpoint blockade: A pan-tumor analysis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3846.

Abstract 6550: Biopsy analysis of trial S1616: Ipilimumab plus nivolumab versus ipilimumab alone in patients with anti-PD-1 refractory melanoma

Abstract Background: The phase II randomized trial S1616 (NCT03033576) showed that patients with melanoma refractory to anti-PD-1-based therapy had improved progression free survival (HR=0.63, p=0.037) and objective response (28% vs 9%) to the combination of ipilimumab with nivolumab compared to ipilimumab. Here, we report molecular and spatial proteomic features of biopsies collected from patients on S1616, both prior to and during therapy. Methods: Biopsies collected from patients from both arms at baseline (N=68 patients total) and early on-therapy (N=51; 43 with paired timepoints) were analyzed by whole exome sequencing (n=185 samples), RNA sequencing (n=105), histopathologic staining (n=149), and multiplexed ion beam imaging (n=45). Multiple biopsies were available for some patients. Mutations, gene expression, and tumor microenvironment were compared across timepoints and response to combination (N=18 responders [CR/PR], N=44 nonresponders [SD/PD]). Results: Baseline biopsies from patients responsive to combination had increased expression of genes (n=482, FDR&amp;lt;0.05) associated with coagulation and complement, fatty acid metabolism, oxidative phosphorylation, hypoxia, and interferon gamma response gene sets (FDR&amp;lt;0.05), compared to nonresponsive biopsies. Baseline biopsies from responders also had low levels of effector CD8 T cells (PD1+, TIM-3+, GZMB+, Ki67+) colocalized with tumor cells and myeloid populations expressing higher levels of MHC Class II. On-therapy biopsies from responders showed decreased detection of driver mutations by genomics, reduced gene expression of pathways enriched at baseline (oxidative phosphorylation, complement) by transcriptomics, and increased CD8 T cell to tumor cell ratios by histopathology, supporting observations of tumor regression. On-therapy biopsies from responders also had increased gene expression of genes related to inflammatory cytokine signaling. This correlated with increased proportions of effector CD8 T cells, compared to paired baseline or nonresponding biopsies, and increased organization of nonactivated CD8 T cells near mature endothelial structures (SMA+, CD31+ regions) adjacent to tumor. Biopsies from nonresponders did not demonstrate these dynamics and instead contained exhausted CD8 T cells (PD1+, TIM-3+, granzyme B-, Ki67-) colocalized with FOXP3+, CD4+ Tregs and CD163+, PD-L1+ M2 macrophages, both at baseline and on-therapy. Conclusion: In patients with melanoma refractory to anti-PD-1, addition of anti-CTLA-4 facilitates tumor-reactive CD8 T-cell infiltration and decreased suppressor cell dynamics, resulting in regression of some tumors with distinct transcriptome features. Conversely, biopsies from patients whose tumors progress on combination therapy lack expression of metabolic pathways and show CD8 T-cells restricted in proximity to M2 macrophages and Tregs. Citation Format: Katie M. Campbell, Zaid Bustami, Daniel G. Chen, Egmidio Medina, Cynthia R. Gonzalez, Nataly Naser Aldeen, Ignacio Baselga-Carretero, Agustin Vega-Crespo, Jessica Maxey, Jia M. Chen, Lawrence F. Kuklinski, Kari L. Kendra, Bartosz Chmielowski, Thach-Giao Truong, Nikhil I. Khushalani, Frances Collichio, Alexandra Ikeguchi, Adrienne I. Victor, Kim Margolin, Jeffrey A. Sosman, Sapna P. Patel, Siwen Hu-Lieskovan, James Moon, Shay Bellasea, Daniel K. Wells, Christine N. Spencer, Marshall A. Thompson, Michael Wu, Philip O. Scumpia, Ari VanderWalde, Antoni Ribas. Biopsy analysis of trial S1616: Ipilimumab plus nivolumab versus ipilimumab alone in patients with anti-PD-1 refractory melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 6550.

Abstract 1952: Co-alterations in PIK3CA and ARID1A lead to enhanced sensitivity to PI3K inhibition

Abstract Background: There is increasing interest in developing precision medicine strategies for cancers with PIK3CA mutations. Co-alterations in PIK3CA and ARID1A (AD) occur in ~1% of all cancers. Previously, patients with co-alterations in PIK3CA and AD have shown both an improved objective response rate and improved progression free survival following copanlisib (cop) treatment compared to cancers with PIK3CA mutations and wild-type AD. Here we evaluate potential mechanisms for this enhanced clinical benefit. Methods: AD was knocked out in SW48 and SW48PIK3CA-H1047R (SW48PK) human 2D colorectal cancer cell lines using CRISPR (SW48AD; SW48PKAD). Knockouts were confirmed using PCR genotyping, amplicon sequencing, and western blot (WB). A cell proliferation assay (WST-1) was performed at increasing doses of cop for 48hrs to determine cell viability. WBs were performed at 6hrs and 24hrs after cop treatment to determine levels of phosphorylation of AKT, S6, and 4EBP1 and levels of apoptosis-related proteins (MCL-1, BCL-xL, BCL-2, PARP). Athymic nude mice were flank injected with SW48PK and SW48PKAD and treated with cop (10mg/kg in PEG400/acidified water (0.1N HCl, pH 3.5; 20/80, v/v) or vehicle for 25 days or until moribund. Results: WST-1 assay showed highest sensitivity to cop in SW48PKAD cells compared to SW48, SW48PK and SW48AD. At 10nM (p=0.01), there was a significant difference in cell viability between SW48PK and SW48PKAD. No significant difference was seen in the phosphorylation (p) of AKT, S6, or 4EBP1 between SW48PK and SW48PKAD. Expression of MCL-1 protein decreased in SW48PKAD compared to SW48PK. No difference was seen in levels of BCL-xL and BCL-2. On treatment with cop, there was a greater reduction in pS6 in SW48PKAD at 24 hours compared to SW48PK, but no significant difference in pAKT and p4EBP1. There was a gradual increase in MCL-1, BCL-xL, and cleaved PARP in SW48PKAD overtime following cop treatment compared to SW48PK. In vivo, untreated SW48PKAD tumors grew more quickly than the SW48PK tumors (8-fold increase in tumor size in SW48PKAD compared to 5-fold increase in SW48PK by day 25, p=0.06). SW48PKAD mice had significant tumor reduction (p=0.002) on cop treatment by day 25; however, SW48PK mice did not. Conclusions: ARID1A loss along with PIK3CA mutation leads to greater PI3K inhibition response most likely due to enhanced induction of apoptosis. Further confirmation of this enhanced sensitivity is required with better in vitro models such as patient-derived cancer organoids. Citation Format: Shirsa Udgata, Jordan N. Stoecker, Anna L. Lippert, Cheri A. Pasch, Dustin A. Deming. Co-alterations in PIK3CA and ARID1A lead to enhanced sensitivity to PI3K inhibition [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1952.

Abstract 7654: Tertiary lymphoid structure associates with poor prognosis in locally advanced esophageal squamous cell carcinoma treated with neoadjuvant chemoradiotherapy

Abstract Introduction: Tertiary lymphoid structure (TLS) has been found to associate with good prognosis in various cancer types including esophageal squamous cell carcinoma (ESCC). A recent study involving patients receiving curative surgical resection alone for localized ESCC showed TLS as a favorable prognostic factor associated with improved progression free survival (Hayashi et al. British Journal of Cancer, 2023;128:2175-2185). Our study aimed to investigate the prognostic significance of TLS in patients with locally advanced ESCC receiving neoadjuvant chemoradiotherapy (CRT). Patients and Methods: We retrospectively enrolled 137 patients of locally advanced ESCC patients from two referral centers of Taiwan from 2002 to 2018. All patients received paclitaxel/platinum-based CRT followed by esophagectomy. Primary esophageal tumor tissues biopsied endoscopically before treatment were collected for immunohistochemical stains for CD20 (clone L26; Zytomed, Berlin, Germany) and CD23 (clone DAK-CD23; agilent Dako, California, U.S.A.). The TLS status of each patient was defined as no TLS (no aggregation of CD20-positive cells), immature TLS (aggregation of CD20-positive cells without CD23-positive cells in it), and mature TLS (aggregation of CD20-positive cells with CD23-positive cells in it). The associations of the TLS status with pathologic complete response (pCR) and overall survival (OS) were analyzed univariately and multivariately by logistic regression and cox regression, respectively. The variables included in the analyses were age, gender, tumor location, clinical T stage, clinical N stage, the institutes, PD-L1 expression on tumor cells (PD-L1 TC) and immune cells (PD-L1 IC), and the TLS status. Results: The median age was 54 years with 125 males and 12 females. The TLS status of no, immature, and mature TLS were seen in 64, 40, and 33 patients, respectively. Mature TLS was associated with PD-L1 IC (p=0.0007). Compared to no TLS, mature TLS associated with lower pCR rate (24% vs 47%) in both univariate (OR: 0.36, p=0.034) and multivariate (OR: 0.26, p=0.023) analysis. Compared to no TLS, mature TLS was associated with shorter OS (median OS: 27 vs 46 months) in multivariate analysis (HR: 2.96, p=0.0008), but not in univariate analysis (HR: 1.29, p=0.29). Other prognostic factors associated with OS in multivariate analysis include male gender (HR: 2.88, p=0.021), PD-L1 TC (HR: 1.62, p=0.039), and PD-L1 IC (HR: 0.30, p&amp;lt;0.0001). Conclusion: Mature TLS is an independent factor for poor treatment outcomes, including pathologic response and overall survival in locally advanced ESCC patients receiving neoadjuvant CRT. Additional studies are warranted to validate this finding. (The study was supported by the grant NTUH 110-S5021, MOST 108-2314-B-002-076-MY3, and MOHW 111-TDU-B-221-114006) Citation Format: Ta-Chen Huang, Cher-Wei Liang, Yu-I Li, Jhe-Cyuan Guo, Chia-Chi Lin, Jang-Ming Lee, Yin-Kai Chao, Chih-Hung Hsu. Tertiary lymphoid structure associates with poor prognosis in locally advanced esophageal squamous cell carcinoma treated with neoadjuvant chemoradiotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7654.

Abstract 1224: 3D models of chemotherapy- and PARPi-resistant ovarian cancer indicate essential roles for JAK/STAT signaling in mediating drug resistance

Abstract Ovarian cancer is the deadliest gynecological cancer with a low 5-year overall survival rate that affects over 300,000 women globally each year. Given lack of routine screening procedures, ovarian cancer patients are frequently diagnosed with late-stage disease that rapidly progress despite initial responses to front line therapy. PARPi and VEGFi targeted therapies have improved progression free survival in small subsets of patients but have largely failed to improve overall survival. Since the robust uptake of PARPis in the front line setting, resistance to this class of drugs is a growing problem. The literature is filled with many novel treatment approaches, but the vast majority fail to gain traction in pre-clinical models and early phase trials. A contributing factor to these disappointments relates to the prevalent use of 2D monoculture model systems that do not recapitulate the tumor microenvironment. To address this issue, we utilized the Rastrum 3D cell printer to grow ovarian cancer cells and PDX models in bio-functional matrices which provide optimal stiffness and extracellular matrix components specific to the ovarian tumor microenvironment. We found that ovarian cancer cells grown under these conditions exhibit dramatic up-regulation of the JAK/STAT signaling pathway, including autocrine/paracrine signaling factors, which correlated with increased sensitivity to JAK/STAT inhibitors. This affect was lost when STAT1 and STAT3 knockout cell lines were grown in this 3D environment. Ovarian tumors are known to be rich in cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). We incorporated primary CAFs into this 3D culture system and found they could promote ovarian cancer cell growth only in cancer cells with intact JAK/STAT signaling further indicating the essential role of this pathway in mediating tumor progression. Co-culture with M2 macrophages was also found to induce ovarian cancer cell growth, particularly in resistant models. Conversely, co-culture with M1 macrophages inhibited treatment naïve ovarian cancer cell growth but not resistant cell line growth. Single-cell RNAseq of the complex 3D cultures elucidated profound differences in the cross-talk between these cell types that is dependent on cancer cell sensitivity to standard-of-care agents. Finally, the addition of JAK/STAT inhibitors was found to substantially alter this cross-talk between cell types and inhibit cancer cell viability. These data further implicate the importance of JAK/STAT signaling, specifically in clinically relevant 3D models, in supporting ovarian cancer progression and response to chemotherapy and PARPi treatment. Ongoing studies are aimed at confirming these findings in pre-clinical mouse models and to elucidate the most effective JAK/STAT inhibitors in vivo with the goal of informing the design of future clinical trials. Citation Format: Esther Rodman, Xiyin Wang, Hannah Smith, Xiaonan Hou, Scott Kaufmann, John Weroha, John Hawse. 3D models of chemotherapy- and PARPi-resistant ovarian cancer indicate essential roles for JAK/STAT signaling in mediating drug resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1224.

Abstract 7374: Mathematical modeling of targeted radionuclide therapy and CAR-T cell immunotherapy for maximizing therapeutic efficacy in multiple myeloma

Abstract Background: Resistance of cancer cells to monotherapies has led to the development of sequential or combination therapy regimens. However, dosing and scheduling of these therapies is challenging due to the numerous dosing and scheduling combinations that can be given. Mathematical models are thus critical tools for addressing this challenge as multiple therapy combinations can be tested in silico to finalize a patient-specific therapeutic regimen in vivo. Here we develop a mathematical framework for combining targeted radiation therapy (TRT) with Chimeric Antigen Receptor (CAR)-T cell immunotherapy and demonstrate the use of in silico techniques to schedule these therapies for maximizing survival. Methods: In the mathematical framework tumor growth is assumed to be exponential and the effect of radiation on both tumor cells and CAR-T cells is modeled using the linear-quadratic model of cell survival to radiation. A predator-prey model is used to characterize the dynamics of tumor and CAR-T cells. Using a preclinical disseminated mouse model of multiple myeloma (MM1S), we evaluate tumor response to 200 nCi of 225Ac-DOTA-Daratumumab (TRT) and 1 million cells of CS1 CAR-T cell therapy both as monotherapies as well as in combination. Tumor burden tracked using bioluminescence imaging from six groups of mice is used to calibrate model parameters: (a) No treatment. (b) Day 7 TRT. (c) Day 7 CAR-T cell therapy. (d) Day 7 TRT + Day 18 CAR-T cell therapy. (e) Day 7 TRT + Day 25 CAR-T cell therapy. (f) Day 7 TRT + Day 32 CAR-T cell therapy. Response to therapy is evaluated using progression-free survival (PFS), overall survival (OS) and time to minimum tumor burden (tmin), all of which are calculated using the predicted in silico tumor burden dynamics and the tumor burden at the start of first therapy. We evaluate these response metrics for various dosing and scheduling regimens. Results: Therapy intervals that were too short or too long are shown to be detrimental for therapeutic efficacy. TRT too close to CAR-T cell therapy results in radiation related CAR-T cell killing, while the interval being too long results in tumor regrowth, negatively impacting tumor control and survival. If a single dose is split into multiple doses, the splitting is advantageous only if the first therapy delivered can produce a significant benefit as a monotherapy. Based on the model parameters we estimate the minimum required TRT activity and CAR-T cell dose to demonstrate an improvement in PFS. Conclusions: The proposed model demonstrates the impact of different dosing and scheduling regimens of TRT and CAR-T therapy on survival metrics. It is a potent tool for translating preclinical results to the clinic and eventually tailor therapy regimens for patients. Citation Format: Vikram Adhikarla, Dennis Awuah, Enrico Caserta, Megan Minnix, Maxim Kuznetsov, Amrita Krishnan, Jeffrey Y. Wong, John E. Shively, Xiuli Wang, Flavia Pichiorri, Russell C. Rockne. Mathematical modeling of targeted radionuclide therapy and CAR-T cell immunotherapy for maximizing therapeutic efficacy in multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7374.

Abstract 5080: Antibody drug conjugate trastuzumab deruxtecan suppresses leptomeningeal brain metastasis cells and is potentiated by addition of immune check point inhibitor

Abstract Leptomeningeal disease (LMD) is defined by dissemination of metastatic cancer cells into the subarachnoid space with subsequent involvement of the cerebrospinal fluid and leptomeninges. LMD is an aggressive, late-stage development of cancer, which is increasing in prevalence as improved treatments for systemic malignancies are discovered. It leads to significant neurological morbidity and mortality, and outcomes remain poor despite improving cancer treatment strategies. There is a large population of patients with human epidermal growth factor receptor 2 (HER2) expressing cancers, such as breast and lung cancers, who suffer from leptomeningeal metastasis. There has been evolving research looking at antibody drug conjugates for treatment of these primary pathologies, such as Trastuzumab Deruxtecan (TDxd), which shows improved progression free survival and overall survival in those with HER2 expressing primary cancers, as well as in intraparenchymal brain metastasis. However, as of yet there has been no study of its utility in LMD. Additionally, use of immune check point inhibitors (ICI) for treatment of LMD has been studied, showing some efficacy, but less robust response than that in intraparenchymal brain metastasis. Given the significant population of patients who continue to be affected by leptomeningeal metastasis, there is significant need for an improved treatment regimen. We hypothesize that TDxd will have a killing effect on HER2 expressing LMD cells, which can be further potentiated by the addition of ICIs. To test this hypothesis, we developed breast and lung cancer cell lines (SKBrM-LMD, and H2030BrM-LMD) that express HER2 and preferentially metastasize to leptomeningeal space. These cell lines were also labeled with luciferase. We then treated these cell lines with TDxd and found that TDxd had significant growth inhibitory effect on these cells in vitro when compared to the control. Furthermore, we educated human T Cells against the SkBrM-LMD cells and treated these cells with the aforementioned T cells plus the ICI Anti-PD1. Our results showed that ICI had significant killing effect when compared to the control. We have also created an in vivo LMD model by performing intraventricular injection of HER2 expressing tumor cells into a mouse model, which can be used for testing the efficacy of TDxd and ICI by intrathecal injection. In conclusion, our results indicate that TDxd and ICI have significant killing activity against HER2 expressing LMD cells, and therefore intrathecal administration of these drugs is a promising treatment modality that will be demonstrated using a mouse LMD model. Citation Format: Eleanor C. Smith, Shih-Ying Wu, Ravindra P. Deshpande, Abhishek Tyagi, Kounosuke Watabe. Antibody drug conjugate trastuzumab deruxtecan suppresses leptomeningeal brain metastasis cells and is potentiated by addition of immune check point inhibitor [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5080.