Prognostic relevance of clonal hematopoiesis in myeloid neoplastic transformation in patients with follicular lymphoma treated with radioimmunotherapy.

While novel radioisotope therapies continue to advance cancer care, reports of therapy-related myeloid neoplasms (t-MN) have generated concern. The prevalence and role of clonal hematopoiesis (CH) in this process remain to be defined. We hypothesized that: (i) CH is prevalent in relapsed follicular lymphoma and is associated with t-MN transformation, and (ii) radiation in the form of radioimmunotherapy (RIT) plays a role in clonal progression. In this retrospective cohort study, we evaluated the prevalence and prognostic impact of CH on clinical outcomes in 58 heavily pre-treated follicular lymphoma patients who received RIT. Patients had been given a median of four lines of therapy before RIT. The prevalence of CH prior to RIT was 46%, while it was 67% (P=0.15) during the course of RIT and subsequent therapies in the paired samples. Fourteen (24%) patients developed t-MN. Patients with t-MN had a higher variant allele fraction (38% vs. 15%; P=0.02) and clonal complexity (P=0.03) than those without. The spectrum of CH differed from that in age-related CH, with a high prevalence of DNA damage repair and response pathway mutations, absence of spliceosome mutations, and a paucity of signaling mutations. While there were no clear clinical associations between RIT and t-MN, or overall survival, patients with t-MN had a higher mutant clonal burden, along with extensive chromosomal abnormalities (median survival, afer t-MN diagnosis, 0.9 months). The baseline prevalence of CH was high, with an increase in prevalence on exposure to RIT and subsequent therapies. The high rates of t-MN with marked clonal complexities and extensive chromosomal damage underscore the importance of better identifying and studying genotoxic stressors accentuated by therapeutic modalities.

Selective Personalized RadioImmunotherapy for Locally Advanced Non-Small-Cell Lung Cancer Trial (SPRINT).

PURPOSE: Standard therapy for locally advanced non-small-cell lung cancer (LA-NSCLC) is concurrent chemoradiotherapy followed by adjuvant durvalumab. For biomarker-selected patients with LA-NSCLC, we hypothesized that sequential pembrolizumab and risk-adapted radiotherapy, without chemotherapy, would be well-tolerated and effective. METHODS: Patients with stage III NSCLC or unresectable stage II NSCLC and an Eastern Cooperative Oncology Group performance status of 0-1 were eligible for this trial. Patients with a PD-L1 tumor proportion score (TPS) of ≥50% received three cycles of induction pembrolizumab (200 mg, once every 21 days), followed by a 20-fraction course of risk-adapted thoracic radiotherapy (55 Gy delivered to tumors or lymph nodes with metabolic volume exceeding 20 cc, 48 Gy delivered to smaller lesions), followed by consolidation pembrolizumab to complete a 1-year treatment course. The primary study end point was 1-year progression-free survival (PFS). Secondary end points included response rates after induction pembrolizumab, overall survival (OS), and adverse events. RESULTS: Twenty-five patients with a PD-L1 TPS of ≥50% were enrolled. The median age was 71, most patients (88%) had stage IIIA or IIIB disease, and the median PD-L1 TPS was 75%. Two patients developed disease progression during induction pembrolizumab, and two patients discontinued pembrolizumab after one infusion because of immune-related adverse events. Using RECIST criteria, 12 patients (48%) exhibited a partial or complete response after induction pembrolizumab. Twenty-four patients (96%) received definitive thoracic radiotherapy. The 1-year PFS rate is 76%, satisfying our efficacy objective. One- and 2-year OS rates are 92% and 76%, respectively. The most common grade 3 adverse events were colitis (n = 2, 8%) and esophagitis (n = 2, 8%), and no higher-grade treatment-related adverse events have occurred. CONCLUSION: Pembrolizumab and risk-adapted radiotherapy, without chemotherapy, are a promising treatment approach for patients with LA-NSCLC with a PD-L1 TPS of ≥50%.

Radioimmunotherapy with 131 I-rituximab for patients with relapsed or refractory follicular or mantle cell lymphoma.

AIM: This study aimed to evaluate the safety and efficacy of 131 I-rituximab in patients with relapsed or refractory follicular or mantle cell lymphoma. METHODS: Twenty-four patients with relapsed or refractory follicular or mantle cell lymphoma were administered unlabeled rituximab (70 mg) immediately before receiving a therapeutic dose of 131 I-rituximab. Contrast-enhanced 18F-fluorodeoxyglucose positron emission tomography/computed tomography was used a month later to assess tumor response. RESULTS: This study enrolled 24 patients between June 2012 and 2022. Depending on how they responded to radioimmunotherapy (RIT), 131 I-rituximab was administered one to five times. Of the 24 patients, 9 achieved complete response after RIT and 8 achieved partial response. The median progression-free and overall survival was 5.9 and 37.9 months, respectively. During the follow-up period of 64.2 months, three patients were diagnosed with a secondary malignancy. Among treatment-related adverse events, hematologic toxicities were common, and grade 3-4 thrombocytopenia and neutropenia were reported in 66.6% of cases. CONCLUSION: 131 I-rituximab has an effective and favorable safety profile in patients with relapsed or refractory follicular lymphoma and mantle cell lymphoma. This suggests that RIT may also be considered a treatment option for patients with relapsed or refractory follicular lymphoma and mantle cell lymphoma.

Gut microbiota: A novel and potential target for radioimmunotherapy in colorectal cancer.

Colorectal cancer (CRC) is one of the most common cancers, with a high mortality rate, and is a major burden on human health worldwide. Gut microbiota regulate human immunity and metabolism through producing numerous metabolites, which act as signaling molecules and substrates for metabolic reactions in various biological processes. The importance of host-gut microbiota interactions in immunometabolic mechanisms in CRC is increasingly recognized, and interest in modulating the microbiota to improve patient's response to therapy has been raising. However, the specific mechanisms by which gut microbiota interact with immunotherapy and radiotherapy remain incongruent. Here we review recent advances and discuss the feasibility of gut microbiota as a regulatory target to enhance the immunogenicity of CRC, improve the radiosensitivity of colorectal tumor cells and ameliorate complications such as radiotoxicity. Currently, great breakthroughs in the treatment of non-small cell lung cancer and others have been achieved by radioimmunotherapy, but radioimmunotherapy alone has not been effective in CRC patients. By summarizing the recent preclinical and clinical evidence and considering regulatory roles played by microflora in the gut, such as anti-tumor immunity, we discuss the potential of targeting gut microbiota to enhance the efficacy of radioimmunotherapy in CRC and expect this review can provide references and fresh ideas for the clinical application of this novel strategy.

Estimating the Risk for Secondary Cancer After Targeted α-Therapy with 211At Intraperitoneal Radioimmunotherapy.

Intraperitoneal 211At-based targeted α-therapy (TAT) may hold great promise as an adjuvant therapy after surgery and chemotherapy in epithelial ovarian cancer to eradicate any remaining undetectable disease. This implies that it will also be delivered to patients possibly already cured by the primary treatment. An estimate of long-term risks is therefore sought to determine whether the treatment is justified. Methods: Baseline data for risk estimates of α-particle irradiation were collected from published studies on excess cancer induction and mortality for subjects exposed to either 224Ra treatments or Thorotrast contrast agent (25% ThO2 colloid, containing 232Th). Organ dosimetry for 224Ra and Thorotrast irradiation were taken from the literature. These organ-specific risks were then applied to our previously reported dosimetry for intraperitoneal 211At-TAT patients. Results: Risk could be estimated for 10 different organ or organ groups. The calculated excess relative risk per gray (ERR/Gy) could be sorted into 2 groups. The lower-ERR/Gy group, ranging up to a value of approximately 5, included trachea, bronchus, and lung, at 0.52 (95% CI, 0.21-0.82); stomach, at 1.4 (95% CI, -5.0-7.9); lymphoid and hematopoietic system, at 2.17 (95% CI, 1.7-2.7); bone and articular cartilage, at 2.6 (95% CI, 2.0-3.3); breast, at 3.45 (95% CI, -10-17); and colon, at 4.5 (95% CI, -3.5-13). The higher-ERR/Gy group, ranging from approximately 10 to 15, included urinary bladder, at 10.1 (95% CI, 1.4-23); liver, at 14.2 (95% CI, 13-16); kidney, at 14.9 (95% CI, 3.9-26); and lip, oral cavity, and pharynx, at 15.20 (95% CI, 2.73-27.63). Applying a typical candidate patient (female, age 65 y) and correcting for the reference population mortality rate, the total estimated excess mortality for an intraperitoneal 211At-monoclonal antibody treatment amounted to 1.13 per 100 treated. More than half this excess originated from urinary bladder and kidney, 0.29 and 0.34, respectively. Depending on various adjustments in calculation and assumptions on competing risks, excess mortality could range from 0.11 to 1.84 per 100 treated. Conclusion: Published epidemiologic data on lifelong detriment after α-particle irradiation and its dosimetry allowed calculations to estimate the risk for secondary cancer after 211At-based intraperitoneal TAT. Measures to reduce dose to the urinary organs may further decrease the estimated relative low risk for secondary cancer from 211At-monoclonal antibody-based intraperitoneal TAT.

Real World Long-term Follow-up Experience with Yttrium-90 ibritumomab tiuxetan in Previously Untreated Patients with Low-Grade Follicular Lymphoma and Marginal Zone Lymphoma.

INTRODUCTION: Yttrium-90 ibritumomab tiuxetan [(90)Y-IT] is a CD20-targeted radio-immuno conjugate. Clinical trials of (90)Y-IT as a first-line stand-alone treatment in follicular lymphoma (FL) and/or marginal zone lymphoma (MZL) showed high efficacy. However, long-term survival outcomes and toxicities are not well-defined. METHODS: We report a retrospective single-institution, multi-center study of (90)Y-IT in previously untreated low grade (LG)-FL and MZL at Mayo Clinic Cancer Center between January 2000 and October 2019. We selected patients with LG-FL and MZL who received standard-dose (90)Y-IT as a single agent in the first line setting. RESULTS: The cohort (n = 51) consists of previously untreated LG-FL (n = 41) or MZL (n = 10). Median follow-up was 5.3 years (95% CI; 4.2, 6.2). Overall response rate (ORR) was 100% with complete response rate (CR) of 94%. Continuous CR was observed in 59% patients who had more than 2 years of follow-up. Long-term CR (>7 years) was seen in 25% of patients. Median progression free survival (mPFS) for the whole cohort was not reached (NR) (95% CI; 4.9, NR). Bulky disease was associated with shorter median PFS of 3.5 years (CI 95%; 0.8, 4.9) compared to non-bulky disease NR (CI 95%; 5.8, NR), P = .02. The incidence of grade 3 or higher thrombocytopenia, neutropenia and anemia were 47%, 37%, and 4% respectively. No therapy-related myelodysplasia or acute myeloid leukemia were observed. CONCLUSION: Long real-life follow-up showed that single-agent (90)Y-IT is highly efficacious with durable long-term survival in previously untreated LG-FL and MZL without significant risk for secondary malignancies.

90-yttrium-ibritumomab tiuxetan as first-line treatment for follicular lymphoma: updated efficacy and safety results at an extended median follow-up of 9.6 years.

Radioimmunotherapy with 90-yttrium-ibritumomab tiuxetan (90Y-IT) as first-line treatment in patients with follicular lymphoma (FL) demonstrated promising results with a complete remission (CR) rate of 56% and a median progression-free survival (PFS) of 26 months, when initially analyzed after a median follow-up of 30.6 months. The aim of this long-term follow-up was to investigate whether clinical benefits were maintained and new safety signals appeared. Fifty-nine patients, aged ≥ 50 years, with FL grade 1 to 3A in stages II to IV were treated with 90Y-IT as first-line therapy. If CR without evidence of minimal residual disease (MRD), partial response or stable disease was achieved 6 months after treatment, patients were observed without further treatment. Patients with CR but persisting MRD received consolidation therapy with rituximab. The primary endpoint was the clinical response rate. Secondary endpoints were time to progression, safety, and tolerability. After a median follow-up of 9.6 years, median PFS was 3.6 years, and 8-year PFS was 38.3%. Median overall survival (OS) was not reached during the extended follow-up, and 8-year OS amounted to 69.2%. Age 65 years and above or disease progression within 24 months of treatment were significantly associated with shorter OS. An important finding was the lack of new safety signals. In particular, no increase in secondary malignancies or transformation into aggressive lymphoma was observed compared to trials with a similar follow-up. In summary, 90Y-IT as first-line treatment demonstrates a favorable safety profile and long-term clinical activity in a substantial fraction of FL patients in need of therapy. ClinicalTrials.gov Identifier: NCT00772655.

Induction chemoimmunotherapy followed by CD8+ immune cell-based patient selection for chemotherapy-free radioimmunotherapy in locally advanced head and neck cancer.

PURPOSE: The first aim of the trial is to study feasibility of combined programmed death protein ligand 1/cytotoxic T-lymphocyte-associated protein 4 inhibition concomitant to radiotherapy. In addition, efficacy of the entire treatment scheme consisting of induction chemoimmunotherapy followed by chemotherapy-free radioimmunotherapy (RIT) after intratumoral CD8 +immune cell-based patient selection will be analyzed. METHODS: Patients with stage III-IVB head and neck squamous cell carcinoma were eligible for this multicenter phase II trial. Treatment consisted of a single cycle of cisplatin 30 mg/m² days 1-3, docetaxel 75 mg/m² day 1, durvalumab 1500 mg fix dose day 5 and tremelimumab 75 mg fix dose day 5. Patients with increased intratumoral CD8 +immune cell density or pathological complete response (pCR) in the rebiopsy entered RIT up to a total dose of 70 Gy. Patients received further three cycles of durvalumab/tremelimumab followed by eight cycles of durvalumab mono (every 4 weeks). The intended treatment for patients not meeting these criteria was standard radiochemotherapy outside the trial. Primary endpoint was a feasibility rate of patients entering RIT to receive treatment until at least cycle 6 of immunotherapy of ≥80%. RESULTS: Between September 2018 and May 2020, 80 patients were enrolled (one excluded). Out of these, 23 patients had human papilloma virus (HPV)-positive oropharyngeal cancer. Median follow-up was 17.2 months. After induction chemoimmunotherapy 41 patients had pCR and 31 had increased intratumoral CD8 +immune cells. Of 60 patients entering RIT (primary endpoint cohort), 10 experienced imiting toxic (mainly hepatitis) and four discontinued for other reasons, resulting in a feasibility rate of 82%. The RIT cohort (n=60) had a progression-free survival (PFS) rate at one and 2 years of 78% and 72%, respectively, and an overall survival rate at one and 2 years of 90% and 84%, respectively. Patients with HPV-positive oropharyngeal cancers had greater benefit from RIT with a 2-year PFS rate of 94% compared with 64% for HPV-negative oropharyngeal cancers and other locations. In the entire study cohort (n=79) the 2-year PFS rate was 68% (91% for HPV-positive oropharynx vs 59% for others). Toxicity grade 3-4 mainly consisted of dysphagia (53%), leukopenia (52%) and infections (32%). CONCLUSIONS: The trial met the primary endpoint feasibility of RIT. Induction chemo-immunotherapy followed by chemotherapy-free RIT after intratumoral CD8 +immune cell-based patient selection has promising PFS. TRIAL REGISTRATION NUMBER: The trial was registered with ClinicalTrials.gov (identifier: NCT03426657). The trial was conducted as investigator-sponsored trial (IST).

Pretherapeutic estimated glomerular filtration rate predicts development of chronic kidney disease in patients receiving PSMA-targeted radioligand therapy.

BACKGROUND: Prostate-specific membrane antigen (PSMA)-targeted radioligand therapy (RLT) may be associated with renal toxicity. We aimed to identify predictive parameters for the development of chronic kidney disease (CKD) in patients with metastatic castration resistant prostate cancer (mCRPC) undergoing RLT. METHODS: In 46 mCRPC patients scheduled for Lu-177-PSMA-RLT, pretherapeutic estimated glomerular filtration rate (eGFR [ml/min/1.73 m2 ]), Tc-99m-mercaptoacetyltriglycine (Tc-99m-MAG3) clearance and baseline Ga-68-PSMA-ligand positron emission tomography (PET)-derived renal cortical uptake and PSMA-tumor volume (TV) were determined. We tested the predictive capability of these parameters and clinical risk factors for the occurrence of CKD (defined as CTCAE vers. 5.0 grade 2 or higher) during follow-up. RESULTS: After 4 ± 3 cycles of RLT average eGFR declined from 76 ± 17 to 72 ± 20 ml/min/1.73 m2 (p = 0.003). Increased estimated renal radiation dose (eRRD) was significantly associated with renal functional decline (p = 0.008). During follow-up, 16/46 (30.4%) developed CKD grade 2 (no grade 3 or higher). In receiver operating characteristic (ROC) analysis, pretherapeutic eGFR was highly accurate in identifying the occurrence of CKD vs no CKD with an area under the curve (AUC) of 0.945 (p < 0.001; best threshold, 77 ml/min/1.73 m2 ), followed by Tc-99m-MAG3-derived tubular extraction rate (TER; AUC, 0.831, p < 0.001; best threshold, 200 ml/min/1.73 m2 ). Renal PET signal (p = 0.751) and PSMA-TV (p = 0.942), however, were not predictive. Kaplan-Meier analyses revealed adverse renal outcome for patients with lower eGFR (p = 0.001) and lower scintigraphy-derived TER (p = 0.009), with pretherapeutic eGFR emerging as the sole predictive parameter in multivariate analysis (p = 0.007). CONCLUSION: Serious adverse renal events are not a frequent phenomenon after PSMA-targeted RLT. However, in patients developing moderate CKD after RLT, pretherapeutic eGFR is an independent predictor for renal impairment during follow-up.

Adverse events of radioimmunotherapy for non-Hodgkin lymphoma: A systematic review and meta-analysis.

Non-Hodgkin's lymphoma continues to be a highly prevalent entity in the general population. Currently, there are multiple treatment schemes based on chemotherapeutic agents with a great success rate. However, there is a non-negligible percentage of patients who may relapse or be refractory. In this sense, new therapeutic options have emerged in the search for adequate responses, such as monoclonal antibodies that target the CD20 molecule. Another valid option is radioimmunotherapy (RIT), which combines using monoclonal antibodies for the specific targeting of malignant cells and radiation to destroy these cells. Despite the promising results that favor RIT in several clinical studies in different target populations and types of NHL, one situation to consider is the association of this therapy and second neoplasms (acute myeloid leukemia (AML) or myelodysplastic syndrome (MSD)). In this sense, we have proposed this meta-analysis to analyze the published information and determine the incidence of this association and determine this therapy's safety.

Evaluation of practical experiences of German speaking radiation oncologists in combining radiation therapy with checkpoint blockade.

The results of this survey reveal current clinical practice in the handling of combined radioimmunotherapy with Immune Checkpoint Inhibitors (RT + ICI). We aim to provide a basis to open a discussion for clinical application of RT + ICI by analyzation of experts' assessment. We conducted a survey with 24 items with a focus on side effects of RT + ICI, common practice of scheduling and handling of adverse events. After pilot testing by radiation oncology experts the link to the online survey was sent to all members of the German Society of Radiation Oncology (DEGRO). In total, 51 radiation oncologists completed the questionnaire. Pulmonary toxicity under RT + ICI with ICIs was reported most frequently. Consensus was observed for bone and soft tissue RT of the limbs in favor for no interruption of ICIs. For cranial RT half of the participants do not suspend ICIs during normofractionated radiotherapy (nfRT) or stereotactic hypofractionated RT (SRT). More participants pause ICIs for central than for peripheral thoracic region. Maintenance therapy with ICIs is mostly not interrupted prior to RT. For management of RT associated pneumonitis under durvalumab the majority of 86.3% suggest corticosteroid therapy and 76.5% would postpone the next cycle of ICI therapy. The here obtained assessment and experiences by radiation oncologists reveal a large variability in practical handling of combined RT + ICI. Until scientific evidence is available a discussion for current clinical application of RT + ICI should be triggered. Interdisciplinary consensus guidelines with practical recommendations are required.

Radiation Safety for Yttrium-90-polymer Composites (RadioGel™) in Therapy of Solid Tumors.

ABSTRACT: Yttrium-90 (90Y)-polymer composite (RadioGel™) is a new cancer therapeutic agent for treating solid tumors by direct interstitial injection. The 90Y-composite comprises insoluble, microscopic yttrium-phosphate particles carried by a sterile, injectable water-polymer (hydrogel) solution that can be placed directly by needle injection into solid tumors. The yttrium-90-RadioGel™ agent was designed to provide a safe, effective, localized, high-dose beta radiation for treating solid tumors. The properties of 90Y-RadioGel™ also make it a relatively safe agent for health care personnel who prepare, handle, and administer the material. The purpose of this work was to demonstrate and characterize radiation safety of the injectable 90Y-RadioGel™ therapeutic agent. Safety in the patient is defined by its ability to target precisely and remain confined within tumor tissue so that radiation doses are imparted to the tumor and not to normal organs and tissues. Radiation safety for health care personnel is defined by the low radiation doses received by persons who prepare and administer the agent. These safety features were demonstrated during experiments, first involving laboratory rabbits and second in cat and dog animal patients that were treated clinically for sarcoma tumors. This paper focuses mainly on the rabbit tissue biodistribution study; follow-on clinical application in cat and dog subjects confirmed the rabbit results. Implanted VX2 liver tumors in the hind limbs of 26 New Zealand White rabbits were treated using tracer amounts of either (a) 90Y-RadioGel™ or (b) 90Y-microparticles in phosphate-buffered saline (PBS) without the gel carrier. Tumor and margin injections were interstitial. Rabbits were euthanized at 48 h or 10 d following injection. Blood and tissues (tumor or tumor margins, liver, lymph nodes, rib bone, kidney, spleen) were collected for liquid scintillation counting using wet-ash procedures. Biodistribution was also analyzed at 10 d post-injection using micro-computed tomography. Thirteen cat and dog subjects were also treated clinically for sarcomas. Liquid scintillation counting at 48 h post-injection of tumors or margins with 90Y-RadioGel™ showed that significant radioactivity was measurable only at the site of administration and that radioactivity above detector background was not found in blood or peripheral organs and tissues. At 10 d post-injection, microCT showed that yttrium phosphate microparticles were confined to the injection site. Yttrium-90 remained where placed and did not migrate away in significant amounts from the injection site. Radiation doses were confined mainly to tumors and margin tissues. During preparation and administration, radiation doses to hands and body of study personnel were negligible. This work showed that 90Y-RadioGel™ can be safely prepared and administered and that radiation doses to cancer patients are confined to tumor and margin tissues rather than to critical normal organs and tissues.

Good Tumor Response to Chemoradioimmunotherapy in dMMR/MSI-H Advanced Colorectal Cancer: A Case Series.

Purpose: Immune checkpoint blockade has led to a significant improvement of patient survival in metastatic colorectal cancer (CRC) with DNA mismatch repair-deficiency (dMMR)/microsatellite instability-high (MSI-H). However, not all these patients are sensitive to monoimmunotherapy. We firstly presented a case series of advanced dMMR/MSI-H CRCs treating with PD-1 inhibitor-based chemoradioimmunotherapy (CRIT). Methods and Materials: We assessed the short-term efficacy and safety of CRIT in advanced dMMR/MSI-H CRCs, and also did next-generation sequencing (NGS) assays. Results: Our analysis included five advanced dMMR/MSI-H CRCs who have received toripalimab-based CRIT. Toripalimab was given 240mg every three weeks, and the radiation dose was 45-50 gray in 25 fractions. Chemotherapy regimens consisted of CAPOX in three patients, capecitabine in one patient, and mFOLFOX6 in one patient. Initially, two patients displayed complete response (CR), and three patients achieved partial response (PR) on imaging findings. Afterwards, one PR patient was confirmed pathological complete response after surgery, leading to three CR cases in total. Hematological toxicity was the most common adverse effect, and only two patients developed mild immune-related adverse effects besides. All the treatment-related adverse events were under control. Based on the NGS results, the median intratumor heterogeneity was 0.19 (range 0-0.957), which was less in CR patients than PR patients (P = 0.019). Genetic mutations at DNA damage repair genes and the JAK1 gene were also observed. Conclusions: For advanced dMMR/MSI-H CRC, anti-PD-1 based CRIT is effective and safe. Further studies are required to better clarify the potential role and mechanism of CRIT as a viable therapeutic strategy in this population.

Neoadjuvant PD-1 Blockade Combined With Chemotherapy Followed by Concurrent Immunoradiotherapy in Locally Advanced Anal Canal Squamous Cell Carcinoma Patients: Antitumor Efficacy, Safety and Biomarker Analysis.

Background: Anal canal squamous cell carcinoma (ACSCC) is an exceedingly rare malignant neoplasm with challenges in sphincter preservation, treatment toxicities and long-term survival. Little is known concerning the activity of PD-1 antibodies in locally advanced ACSCC. This study reports on the efficacy and toxicities of a neoadjuvant PD-1 blockade combined with chemotherapy followed by concurrent immunoradiotherapy in ACSCC patients, and describes biomarkers expression and mutation signatures. Methods: In this cohort study, patients were treated as planned, including four cycles of neoadjuvant PD-1 antibody toripalimab combined with docetaxol and cisplatin, followed by radiotherapy and two cycles of concurrent toripalimab. Multiplex immunofluorescence staining (mIHC) with PD-L1, CD8, CD163, Pan-Keratin and DAPI was performed with the pretreatment tumor tissue. Whole exome sequencing was performed for the primary tumor and peripheral blood mononuclear cells. The primary endpoint was the complete clinical response (cCR) rate at 3 months after overall treatment. Acute and late toxicities graded were assessed prospectively. Results: Five female patients with a median age of 50 years old (range, 43-65 years old), finished treatment as planned. One patient had grade 3 immune related dermatitis. Two patients had grade 3 myelosuppression during neoadjuvant treatment. No severe radiation-related toxicities were noted. Four patients with PD-L1 expression >1% achieved a cCR after neoadjuvant treatment. and the other patient with negative PD-L1 expression also achieved a cCR at 3 months after radiotherapy. All the patients were alive and free from disease and had a normal quality of life, with 19.6-24 months follow up. Inconsistent expression of PD-L1 and CD163 was detected in 3 and 5 patients, respectively. TTN, POLE, MGAM2 were the top mutation frequencies, and 80 significant driver genes were identified. Pathway analysis showed enrichment of apoptosis, Rap1, Ras, and pathways in cancer signaling pathways. Eight significantly deleted regions were identified. Conclusions: This small cohort of locally advanced ACSCC patients had quite satisfactory cCR and sphincter preservation rate, after neoadjuvant PD-1 antibody toripalimab combined with chemotherapy followed by concurrent immunoradiotherapy, with mild acute and long-term toxicities.

Alpha radioimmunotherapy using 225Ac-proteus-DOTA for solid tumors - safety at curative doses.

This is the initial report of an α-based pre-targeted radioimmunotherapy (PRIT) using 225Ac and its theranostic pair, 111In. We call our novel tumor-targeting DOTA-hapten PRIT system "proteus-DOTA" or "Pr." Herein we report the first results of radiochemistry development, radiopharmacology, and stoichiometry of tumor antigen binding, including the role of specific activity, anti-tumor efficacy, and normal tissue toxicity with the Pr-PRIT approach (as α-DOTA-PRIT). A series of α-DOTA-PRIT therapy studies were performed in three solid human cancer xenograft models of colorectal cancer (GPA33), breast cancer (HER2), and neuroblastoma (GD2), including evaluation of chronic toxicity at ~20 weeks of select survivors. Methods: Preliminary biodistribution experiments in SW1222 tumor-bearing mice revealed that 225Ac could not be efficiently pretargeted with current DOTA-Bn hapten utilized for 177Lu or 90Y, leading to poor tumor uptake in vivo. Therefore, we synthesized Pr consisting of an empty DOTA-chelate for 225Ac, tethered via a short polyethylene glycol linker to a lutetium-complexed DOTA for picomolar anti-DOTA chelate single-chain variable fragment (scFv) binding. Pr was radiolabeled with 225Ac and its imaging surrogate, 111In. In vitro studies verified anti-DOTA scFv recognition of [225Ac]Pr, and in vivo biodistribution and clearance studies were performed to evaluate hapten suitability and in vivo targeting efficiency. Results: Intravenously (i.v.) administered 225Ac- or 111In-radiolabeled Pr in mice showed rapid renal clearance and minimal normal tissue retention. In vivo pretargeting studies show high tumor accumulation of Pr (16.71 ± 5.11 %IA/g or 13.19 ± 3.88 %IA/g at 24 h p.i. for [225Ac]Pr and [111In]Pr, respectively) and relatively low uptake in normal tissues (all average ≤ 1.4 %IA/g at 24 h p.i.). Maximum tolerated dose (MTD) was not reached for either [225Ac]Pr alone or pretargeted [225Ac]Pr at administered activities up to 296 kBq/mouse. Single-cycle treatment consisting of α-DOTA-PRIT with either huA33-C825 bispecific anti-tumor/anti-DOTA-hapten antibody (BsAb), anti-HER2-C825 BsAb, or hu3F8-C825 BsAb for targeting GPA33, HER2, or GD2, respectively, was highly effective. In the GPA33 model, no complete responses (CRs) were observed but prolonged overall survival of treated animals was 42 d for α-DOTA-PRIT vs. 25 d for [225Ac]Pr only (P < 0.0001); for GD2, CRs (7/7, 100%) and histologic cures (4/7, 57%); and for HER2, CRs (7/19, 37%) and histologic cures (10/19, 56%) with no acute or chronic toxicity. Conclusions: [225Ac]Pr and its imaging biomarker [111In]Pr demonstrate optimal radiopharmacologic behavior for theranostic applications of α-DOTA-PRIT. For this initial evaluation of efficacy and toxicity, single-cycle treatment regimens were performed in all three systems. Histologic toxicity was not observed, so MTD was not observed. Prolonged overall survival, CRs, and histologic cures were observed in treated animals. In comparison to RIT with anti-tumor IgG antibodies, [225Ac]Pr has a much improved safety profile. Ultimately, these data will be used to guide clinical development of toxicity and efficacy studies of [225Ac]Pr, with the goal of delivering massive lethal doses of radiation to achieve a high probability of cure without toxicity.

Safety Evaluation of an Alpha-Emitter Bismuth-213 Labeled Antibody to (1→3)-ß-Glucan in Healthy Dogs as a Prelude for a Trial in Companion Dogs with Invasive Fungal Infections.

Background: With the limited options available for therapy to treat invasive fungal infections (IFI), radioimmunotherapy (RIT) can potentially offer an effective alternative treatment. Microorganism-specific monoclonal antibodies have shown promising results in the experimental treatment of fungal, bacterial, and viral infections, including our recent and encouraging results from treating mice infected with Blastomyces dermatitidis with 213Bi-labeled antibody 400-2 to (1→3)-ß-glucan. In this work, we performed a safety study of 213Bi-400-2 antibody in healthy dogs as a prelude for a clinical trial in companion dogs with acquired invasive fungal infections and later on in human patients with IFI. Methods: Three female beagle dogs (≈6.1 kg body weight) were treated intravenously with 155.3, 142.5, or 133.2 MBq of 213Bi-400-2 given as three subfractions over an 8 h period. RBC, WBC, platelet, and blood serum biochemistry parameters were measured periodically for 6 months post injection. Results: No significant acute or long-term side effects were observed after RIT injections; only a few parameters were mildly and transiently outside reference change value limits, and a transient atypical morphology was observed in the circulating lymphocyte population of two dogs. Conclusions: These results demonstrate the safety of systemic 213Bi-400-2 administration in dogs and provide encouragement to pursue evaluation of RIT of IFI in companion dogs.

Positron Emission Tomography-Directed Therapy for Patients With Limited-Stage Diffuse Large B-Cell Lymphoma: Results of Intergroup National Clinical Trials Network Study S1001.

PURPOSE: Diffuse large B-cell lymphoma (DLBCL) presents as a limited-stage disease in 25% to 30% of patients, with better overall survival (OS) than that for advanced-stage disease but with continuous relapse regardless of treatment approach. The preferred treatment is abbreviated rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) and radiation therapy. On the basis of promising results of positron emission tomography (PET)-directed treatment approaches, we designed a National Clinical Trials Network (NCTN) study to improve outcomes and decrease toxicity. METHODS: Patients with nonbulky (< 10 cm) stage I/II untreated DLBCL received 3 cycles of standard R-CHOP therapy and underwent a centrally reviewed interim PET/computed tomography scan (iPET). Those with a negative iPET proceeded with 1 additional cycle of R-CHOP, whereas those with a positive iPET received involved field radiation therapy followed by ibritumomab tiuxetan radioimmunotherapy. RESULTS: Of 158 patients enrolled, 132 were eligible and 128 underwent iPET, which was positive in 14 (11%) of the patients. With a median follow-up of 4.92 years (range, 1.1-7.7 years), only 6 patients progressed and 3 died as a result of lymphoma. Eleven patients died as a result of nonlymphoma causes at a median age of 80 years. The 5-year progression-free survival estimate was 87% (95% CI, 79% to 92%) and the OS estimate was 89% (95% CI, 82% to 94%), with iPET-positive and iPET-negative patients having similar outcomes. CONCLUSION: To our knowledge, S1001 is the largest prospective study in the United States of limited-stage DLBCL in the rituximab era, with the best NCTN results in this disease subset. With PET-directed therapy, 89% of the patients with a negative iPET received R-CHOP × 4, and only 11% had a positive iPET and required radiation, with both groups having excellent outcomes. The trial establishes R-CHOP × 4 alone as the new standard approach to limited-stage disease for the absolute majority of patients.

Concurrent Definitive Immunoradiotherapy for Patients with Stage III-IV Head and Neck Cancer and Cisplatin Contraindication.

PURPOSE: Although cisplatin plus radiotherapy is a standard treatment of locally advanced head and neck squamous cell carcinoma (LA-HNSCC), cisplatin contraindication is common. Radiation elicits and promotes tumor-directed immune stimulation, which may potentiate anti-PD-1 therapy. We provide the first efficacy report of combined pembrolizumab and definitive radiotherapy in LA-HNSCC. PATIENTS AND METHODS: This single-arm, multi-institution, phase II study (NCT02609503) enrolled 29 cisplatin-ineligible patients. Patients received radiotherapy concurrently with three cycles of pembrolizumab 200 mg every 3 weeks followed by three adjuvant cycles. The primary endpoint was a progression-free survival (PFS) of ≥16 months. Correlative studies included peripheral blood flow cytometry and Luminex cytokine profiling. RESULTS: Reasons for cisplatin ineligibility included otopathy (69.0%), nephropathy (20.7%), and neuropathy (6.9%). With median follow-up of 21 months, estimated 24-month PFS and overall survival rates were 71% (95% confidence interval, 49%-84%) and 75% (51%-88%). The primary PFS endpoint has exceeded the hypothesis and its median has not been reached. Toxicities were typical of radiotherapy; however, high rates of grade 3/4 lymphopenia (58.6%) were observed. Flow cytometry revealed a relative decline in CD4 T cells and B cells, but not CD8 T cells. Upon treatment, frequencies of transitional B cells and tissue-like memory B cells increased, while resting memory B cells decreased. Patients with progression had greater percentages of baseline naïve B cells and fewer marginal zone B cells. CONCLUSIONS: Pembrolizumab and radiotherapy is efficacious in LA-HNSCC and should be evaluated in a randomized trial. The observed changes in B-cell markers deserve further study both as potential biomarkers and as therapeutic targets.

An autoimmune-based, paraneoplastic neurologic syndrome following checkpoint inhibition and concurrent radiotherapy for merkel cell carcinoma: case report.

PURPOSE: Merkel cell carcinoma is highly sensitive to both radiation and immunotherapy. Moreover, concurrent radioimmunotherapy may capitalize on anti-tumor immune activity and improve Merkel cell treatment response, although an enhanced immune system may cross-react with native tissues and lead to significant sequelae. METHODS: Here we present a case study of a patient with metastatic Merkel cell carcinoma treated with radiotherapy concurrent with pembrolizumab. RESULTS: After radioimmunotherapy, the patient developed sensory neuropathy, visual hallucinations, and mixed motor neuron findings. Neurologic dysfunction progressed to profound gastrointestinal dysmotility necessitating parenteral nutrition and intubation with eventual expiration. CONCLUSION: This case represents a unique autoimmune paraneoplastic neurologic syndrome, likely specific to neuroendocrine tumors and motivated by concurrent radioimmunotherapy. Recognition of the potential role of radioimmunotherapy may provide an advantage in anticipating these severe sequelae.

Radioimmunotherapy of human pancreatic cancer xenografts in NOD-scid mice with [64Cu]Cu-NOTA-panitumumab F(ab')2 alone or combined with radiosensitizing gemcitabine and the PARP inhibitor, rucaparib.

INTRODUCTION: Our objective was to determine the feasibility of extending our previously reported PET imaging study of pancreatic cancer (PnCa) with [64Cu]Cu-NOTA-panitumumab F(ab')2 to radioimmunotherapy (RIT) by exploiting the ß-particle and Auger electron emissions of 64Cu (PET theranostic concept). To enhance the effectiveness of [64Cu]Cu-NOTA-panitumumab F(ab')2, we further combined RIT with radiosensitizing gemcitabine (GEM) and the poly(ADP)ribose polymerase inhibitor (PARPi), rucaparib. METHODS: Normal tissue toxicity was assessed in non-tumor-bearing NOD-scid mice injected i.v. with [64Cu]Cu-NOTA-panitumumab F(ab')2 (1.85-9.25 MBq; 10 µg) or [64Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')2 (12.95 MBq). Body weight was monitored, and hematopoietic (CBC), liver (ALT) and kidney [creatinine (SCr)] toxicity were assessed. RIT studies were performed in NOD-scid mice with s.c. OCIP23 human PnCa patient-derived xenografts (PDX) administered [64Cu]Cu-NOTA-panitumumab F(ab')2 (3.7 MBq; 10 µg), unlabeled panitumumab F(ab')2 (10 µg) or normal saline every two weeks. Subsequent studies evaluated RIT with [64Cu]Cu-NOTA-panitumumab F(ab')2 (12.95 MBq; 10 µg) administered alone or combined with GEM and the PARPi, rucaparib administered on a 14-day treatment cycle for up to 6 cycles in NOD-scid mice with s.c. PANC-1 human PnCa xenografts. The radiation absorbed dose in PANC-1 tumors and normal organs in mice after a single i.v. injection of [64Cu]Cu-NOTA-panitumumab F(ab')2 (12.95 MBq; 10 µg) was estimated based on previously reported biodistribution studies of [64Cu]Cu-NOTA-panitumumab F(ab')2. RESULTS: No normal tissue toxicity was observed in non-tumor-bearing NOD-scid mice administered up to 3.7 MBq (10 µg) of [64Cu]Cu-NOTA-panitumumab F(ab')2 but slightly increased ALT was noted at 9.25 MBq. Administration of [64Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')2 (12.95 MBq; 10 µg) caused some hematopoietic toxicity but no increase in ALT or SCr or decreased body weight. A slight tumor growth delay and increased survival was noted in NOD-scid mice with s.c. OCIP23 PDX treated with [64Cu]Cu-NOTA-panitumumab F(ab')2 (3.7 MBq; 10 µg) or unlabeled panitumumab F(ab')2 (10 µg) compared to normal saline treated mice. RIT with [64Cu]Cu-NOTA-panitumumab F(ab')2 (12.95 MBq; 10 µg) combined with GEM + PARPi for up to 6 cycles was most effective for the treatment of PANC-1 tumors. Tumor doubling time increased to 13.3 ± 0.9 days vs. 7.8 ± 3.7 days for RIT alone and 9.3 ± 2.2 days for normal saline treatment. Median survival was significantly longer (P < 0.05) than in mice treated with normal saline (35 days) for RIT + GEM + PARPi (71 days), GEM + PARPi (44 days) and RIT + GEM (43 days) but not for RIT alone (25 days). RIT + GEM + PARPi provided a longer median survival than RIT (P < 0.01), GEM + PARPi (P = 0.01) but not RIT + GEM (P = 0.23). Nonetheless, PANC-1 tumors grew exponentially in all treatment groups. The absorbed dose in PANC-1 tumors after a single i.v. injection of [64Cu]Cu-NOTA-panitumumab F(ab')2 (12.85 MBq; 10 µg) was 0.8 Gy, while the dose in normal organs ranged from 0.6-1.2 Gy. CONCLUSIONS: We conclude that RIT with [64Cu]Cu-NOTA-panitumumab F(ab')2 did not cause significant normal tissue toxicity but was not effective when administered alone for treatment of PnCa xenografts in NOD-scid mice. Combining RIT with GEM and the PARPi, rucaparib enhanced its effectiveness but tumors continued to grow exponentially. Our results suggest that 64Cu is not feasible for RIT of PnCa due to low tumor absorbed doses. 177Lu which has a higher abundance of moderate energy ß-particle emissions may be more effective than 64Cu. The hematopoietic toxicity of [64Cu]Cu-NOTA-anti-mouse EGFR Ab30 F(ab')2 may be mediated by binding to mouse EGFR expressed on some hematopoietic stem cells. ADVANCES IN KNOWLEDGE AND IMPLICATIONS FOR PATIENT CARE: Direct extension of PET with 64Cu(Cu)-NOTA-panitumumab F(ab')2 to RIT exploiting the ß-particle and Auger electron emissions of 64Cu is not feasible. Theranostic approaches that combine PET with RIT employing 177Lu may be more promising and should be explored.