RARE DISEASE
Pseudomyxoma peritonei
Pseudomyxoma peritonei
Pseudomyxoma peritonei
Synonyms: Adenomucinosis, Gelatinous ascites, PMP
Synonyms: Adenomucinosis, Gelatinous ascites, PMP
Synonyms: Adenomucinosis, Gelatinous ascites, PMP
Drug discovery
3
drugs
With orphan designations
Overview
Pseudomyxoma peritonei (PMP) is a rare, progressive mucinous neoplasm typically arising from appendiceal tumors, causing gelatinous ascites ("jelly belly") and peritoneal implants. It exhibits borderline malignancy, with indolent progression leading to abdominal distension, nutritional compromise, and organ dysfunction. Diagnosis relies on imaging (compartmentalized mucin on CT), tumor markers (CEA, CA19-9), and histology. Gold-standard treatment combines cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) [1][3][8].
Therapies
CRS+HIPEC: Curative intent for resectable disease (5-year survival: 62.5–100% in low-grade vs. 0–65% in high-grade) [1][9].
Systemic chemotherapy: Limited benefit; reserved for unresectable/high-grade cases (e.g., FOLFOX, bevacizumab) [3][13].
Palliative options: Debulking surgery, mucolytics, or pressurized intraperitoneal aerosol chemotherapy (PIPAC) in trials [3][19].
Categories: rare abdominal surgical diseases, rare neoplastic diseases
Research Papers
1,016 drug discovery papers about Pseudomyxoma peritonei, with 4 first-in-class and 3 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
1,016 drug discovery papers about Pseudomyxoma peritonei, with 4 first-in-class and 3 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-08-01 | TPW 8.06 Intestinal Transplantation for End-Stage Recurrent Pseudomyxoma Peritonei: The Impact of Nutritional and Functional Status on Outcomes Following Intestinal Transplantation
Abstract Aim To evaluate how anthropometrics affect post-transplant outcomes in patients with PMP. Intestinal transplantation can extend survival in patients with advanced, recurrent PMP not amenable to cytoreduction. Patient selection is challenging as patients may survive many years with advanced disease, but delaying referral can preclude transplant. Traditional anthropometrics, such as BMI, may be inaccurate due to tumour mass. Methods PMP referrals over a ten-year period were used to obtain anthropometric, demographic and survival data. Skeletal muscle area was measured using pre-transplant L3 CT-scans and adjusted for height to derive the skeletal muscle index (SMI). SMI was categorised as Normal, Class I or Class II depletion (n within 1SD, 2SD>n>1SD, n>2SD respectively) based on sex-adjusted values in a healthy population. Mid-Arm Muscle Circumference (MAMC), Grip Strength and Triceps Skin Fold Thickness (TSF) were also measured. Results Forty-nine referrals were reviewed. 17/49 patients (35%) were transplanted, 22% were listed but not transplanted (usually due to deterioration or debulking surgery), and 43% were never listed (unsuitable). Post-referral survival was significantly longer in transplanted patients compared with non-listed patients (median=4.01 and 0.76 years respectively). SMI, but not BMI, was significantly increased in the transplant group, and patients with normal SMI were more likely to be transplanted (χ2 df=2, p<0.05). SMI Class, MAMC, and TSF were not significantly associated with survival, or hospital/ICU length-of-stay. Conclusions Intestinal transplant for PMP can significantly extend survival. Nutritional status, particularly SMI, influences the decision for transplantation although there is limited evidence to support an association with improved post-transplant outcomes.
2026-07-31 | Clinicopathological features and outcomes in 132 patients with perforated high grade appendiceal mucinous neoplasm treated with cytoreductive surgery and HIPEC - A single institution experience.
Non infiltrative mucinous appendiceal neoplasms are categorized into low grade appendiceal mucinous neoplasms (LAMN) and high grade appendiceal mucinous neoplasms (HAMN). The incidence of lymph node involvement in patients with a HAMN, the need for right hemicolectomy and its impact on prognosis after cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has not been widely studied, nor reported. This was a single institution retrospective analysis of prospectively collected data of patients who underwent CRS and HIPEC for a HAMN between January 2015 and December 2023. Clinicopathological variables such as Peritoneal Cancer Index (PCI), completeness of cytoreduction (CC), histological subtype, lymph node status and survival were analysed. Between 2015 and 2023, 1615 patients underwent CRS and HIPEC for perforated appendiceal tumours. HAMNs were histologically confirmed in 132/1615 (8.2%). CRS and HIPEC was performed for a HAMN diagnosed after appendicectomy in 54/132 (40.9%) and 78 presented with the appendix tumour in situ, proceeding straight to surgery. The peritoneal disease in patients with HAMN was high grade mucinous carcinoma peritonei (MCP) in the majority (58.3%), with the remainder having low grade MCP (15.1%), acellular mucin (12.9%) or no peritoneal disease (13.6%). Overall, 96/132 (72.7%) underwent a right hemicolectomy as part of cytoreduction. Eight patients (8/96, 8.3%) had lymph node involvement in the colectomy specimens. The median PCI for those with nodal metastases (N = 8) was 29 with high grade MCP in all 8. Overall, 37/132 developed recurrence during the study period. All had peritoneal recurrence and 9/37 also had thoracic disease. In the 54 patients who had a HAMN at previous appendicectomy, 20/54 (37%) had no detectable disease on pre-operative imaging. However, histologically confirmed peritoneal disease was detected in the cytoreductive surgery specimen in 7/20 (35%). Less than 10% of patients with a perforated HAMN had involved nodes. Positive lymph node status appeared to be associated with high volume and high grade peritoneal disease. Overall, 35% of patients with a HAMN at appendicectomy had histologically proven peritoneal disease despite normal imaging. CRS and HIPEC is advocated for selected patients with a HAMN, predominantly for peritoneal disease cure and control.
2026-07-27 | Single-Cell Transcriptomic Analysis of Tumor Heterogeneity and the Microenvironment in Pseudomyxoma Peritonei.
Pseudomyxoma peritonei (PMP) is characterized by progressive mucus accumulation, extensive stromal fibrosis, rare extraperitoneal metastasis, limited therapeutic options, and frequent recurrence. However, the microenvironmental ecosystem of PMP, particularly in metastatic lesions, remains poorly understood. Here, we integrated single-cell RNA sequencing, whole-exome sequencing, bulk RNA sequencing, and histopathologic validation to construct a high-resolution atlas of primary and paired metastatic tumors. Epithelial cells showed distinct functional states, including a TFF3+ mucus secretion-associated state and a MACC1+ malignant-associated state. Metastatic lesions showed coordinated microenvironmental reprogramming, including POSTN+ fibrosis-associated fibroblasts, CXCL5+ macrophages linked to local immunosuppressive signaling, and immune exclusion associated with a collagen-rich stromal barrier. We also observed extensive lipid metabolic activity and identified a candidate pro-angiogenic network involving POSTN+ fibroblasts, RSPO3+ pericytes, and endothelial cells, potentially mediated by VEGFA-VEGFR2 signaling. Retrospective observations from three recurrent PMP cases further suggested the potential therapeutic value of VEGFR2-targeted anti-angiogenic therapy. Overall, this study provides a comprehensive single-cell transcriptomic atlas of PMP and a resource for developing novel and combination therapeutic strategies.
2026-07-09 | Temporal Immune and Metabolic Shifts Drive the Anti-Tumor Efficacy of Resiquimod-Loaded Nanoparticles in Peritoneal Carcinomatosis.
Peritoneal carcinomatosis (PC) is an aggressive manifestation of advanced gynecological and gastrointestinal malignancies with high recurrence rates despite cytoreductive surgery and chemotherapy. We developed a cationic liposomal nanoparticle (DSTAP, ∼159 nm) to deliver and retain the toll-like receptor 7/8 agonist Resiquimod (R848) within the peritoneal cavity, aiming to modulate the tumor immune microenvironment (TIME) and improve therapeutic efficacy. DSTAP-R848 was evaluated in murine colorectal and ovarian PC models, alone or combined with oxaliplatin (Oxa). Survival, cure rates, and durable immunity following tumor rechallenge were assessed. Immune polarization was examined by incubating ascites and peritoneal fluid with naïve splenocytes, while flow cytometry and metabolomic profiling characterized intratumoral immune populations and metabolic changes. Combination therapy achieved cure rates of 80% in the colorectal model and 30% in the ovarian model, with no recurrence after rechallenge; Oxa monotherapy yielded no cures. Oxa+DSTAP-R848 increased CD8+ T cells and M1 macrophages, while reducing regulatory T cells and myeloid-derived suppressor cells. Immunosuppressive and glycolytic metabolites progressively declined, correlating with reduced tumor burden. Overall, DSTAP-R848 enhances chemotherapy efficacy by reshaping immune and metabolic pathways and promoting durable anti-tumor immunity in PC.
2026-07-01 | 1446 Intestinal Transplantation for End-Stage Recurrent Pseudomyxoma Peritonei: The Impact of Nutritional and Functional Status on Outcomes Following Intestinal Transplantation
Abstract Aim To evaluate how anthropometrics affect post-transplant outcomes in patients with PMP. Intestinal transplantation can extend survival in patients with advanced, recurrent PMP not amenable to cytoreduction. Patient selection is challenging as patients may survive many years with advanced disease, but delaying referral can preclude transplant. Traditional anthropometrics, such as BMI, may be inaccurate due to tumour mass. Method PMP referrals over a ten-year period were used to obtain anthropometric, demographic and survival data. Skeletal muscle area was measured using pre-transplant L3 CT-scans and adjusted for height to derive the skeletal muscle index (SMI). SMI was categorised as Normal, Class I or Class II depletion (n within 1SD, 2SD>n>1SD, n>2SD respectively) based on sex-adjusted values in a healthy population. Mid-Arm Muscle Circumference (MAMC), Grip Strength and Triceps Skin Fold Thickness (TSF) were also measured. Results Forty-nine referrals were reviewed. 17/49 patients (35%) were transplanted, 22% were listed but not transplanted (usually due to deterioration or debulking surgery), and 43% were never listed (unsuitable). Post-referral survival was significantly increased in the transplanted group compared to the non-listed group (median=4.01 and 0.76 years respectively). SMI, but not BMI, was significantly increased in the transplant group, and patients with normal SMI were more likely to be transplanted (χ2 df=2, p<0.05). SMI Class, MAMC, and TSF were not significantly associated with survival, or hospital/ICU length-of-stay. Conclusions Intestinal transplant for PMP can significantly extend survival. Nutritional status, particularly SMI, is linked to the decision for transplantation although there is limited evidence to support an association with improved post-transplant outcomes.
2026-08-01 | TPW 8.06 Intestinal Transplantation for End-Stage Recurrent Pseudomyxoma Peritonei: The Impact of Nutritional and Functional Status on Outcomes Following Intestinal Transplantation
Abstract Aim To evaluate how anthropometrics affect post-transplant outcomes in patients with PMP. Intestinal transplantation can extend survival in patients with advanced, recurrent PMP not amenable to cytoreduction. Patient selection is challenging as patients may survive many years with advanced disease, but delaying referral can preclude transplant. Traditional anthropometrics, such as BMI, may be inaccurate due to tumour mass. Methods PMP referrals over a ten-year period were used to obtain anthropometric, demographic and survival data. Skeletal muscle area was measured using pre-transplant L3 CT-scans and adjusted for height to derive the skeletal muscle index (SMI). SMI was categorised as Normal, Class I or Class II depletion (n within 1SD, 2SD>n>1SD, n>2SD respectively) based on sex-adjusted values in a healthy population. Mid-Arm Muscle Circumference (MAMC), Grip Strength and Triceps Skin Fold Thickness (TSF) were also measured. Results Forty-nine referrals were reviewed. 17/49 patients (35%) were transplanted, 22% were listed but not transplanted (usually due to deterioration or debulking surgery), and 43% were never listed (unsuitable). Post-referral survival was significantly longer in transplanted patients compared with non-listed patients (median=4.01 and 0.76 years respectively). SMI, but not BMI, was significantly increased in the transplant group, and patients with normal SMI were more likely to be transplanted (χ2 df=2, p<0.05). SMI Class, MAMC, and TSF were not significantly associated with survival, or hospital/ICU length-of-stay. Conclusions Intestinal transplant for PMP can significantly extend survival. Nutritional status, particularly SMI, influences the decision for transplantation although there is limited evidence to support an association with improved post-transplant outcomes.
2026-07-31 | Clinicopathological features and outcomes in 132 patients with perforated high grade appendiceal mucinous neoplasm treated with cytoreductive surgery and HIPEC - A single institution experience.
Non infiltrative mucinous appendiceal neoplasms are categorized into low grade appendiceal mucinous neoplasms (LAMN) and high grade appendiceal mucinous neoplasms (HAMN). The incidence of lymph node involvement in patients with a HAMN, the need for right hemicolectomy and its impact on prognosis after cytoreductive surgery (CRS) with hyperthermic intraperitoneal chemotherapy (HIPEC) has not been widely studied, nor reported. This was a single institution retrospective analysis of prospectively collected data of patients who underwent CRS and HIPEC for a HAMN between January 2015 and December 2023. Clinicopathological variables such as Peritoneal Cancer Index (PCI), completeness of cytoreduction (CC), histological subtype, lymph node status and survival were analysed. Between 2015 and 2023, 1615 patients underwent CRS and HIPEC for perforated appendiceal tumours. HAMNs were histologically confirmed in 132/1615 (8.2%). CRS and HIPEC was performed for a HAMN diagnosed after appendicectomy in 54/132 (40.9%) and 78 presented with the appendix tumour in situ, proceeding straight to surgery. The peritoneal disease in patients with HAMN was high grade mucinous carcinoma peritonei (MCP) in the majority (58.3%), with the remainder having low grade MCP (15.1%), acellular mucin (12.9%) or no peritoneal disease (13.6%). Overall, 96/132 (72.7%) underwent a right hemicolectomy as part of cytoreduction. Eight patients (8/96, 8.3%) had lymph node involvement in the colectomy specimens. The median PCI for those with nodal metastases (N = 8) was 29 with high grade MCP in all 8. Overall, 37/132 developed recurrence during the study period. All had peritoneal recurrence and 9/37 also had thoracic disease. In the 54 patients who had a HAMN at previous appendicectomy, 20/54 (37%) had no detectable disease on pre-operative imaging. However, histologically confirmed peritoneal disease was detected in the cytoreductive surgery specimen in 7/20 (35%). Less than 10% of patients with a perforated HAMN had involved nodes. Positive lymph node status appeared to be associated with high volume and high grade peritoneal disease. Overall, 35% of patients with a HAMN at appendicectomy had histologically proven peritoneal disease despite normal imaging. CRS and HIPEC is advocated for selected patients with a HAMN, predominantly for peritoneal disease cure and control.
2026-07-27 | Single-Cell Transcriptomic Analysis of Tumor Heterogeneity and the Microenvironment in Pseudomyxoma Peritonei.
Pseudomyxoma peritonei (PMP) is characterized by progressive mucus accumulation, extensive stromal fibrosis, rare extraperitoneal metastasis, limited therapeutic options, and frequent recurrence. However, the microenvironmental ecosystem of PMP, particularly in metastatic lesions, remains poorly understood. Here, we integrated single-cell RNA sequencing, whole-exome sequencing, bulk RNA sequencing, and histopathologic validation to construct a high-resolution atlas of primary and paired metastatic tumors. Epithelial cells showed distinct functional states, including a TFF3+ mucus secretion-associated state and a MACC1+ malignant-associated state. Metastatic lesions showed coordinated microenvironmental reprogramming, including POSTN+ fibrosis-associated fibroblasts, CXCL5+ macrophages linked to local immunosuppressive signaling, and immune exclusion associated with a collagen-rich stromal barrier. We also observed extensive lipid metabolic activity and identified a candidate pro-angiogenic network involving POSTN+ fibroblasts, RSPO3+ pericytes, and endothelial cells, potentially mediated by VEGFA-VEGFR2 signaling. Retrospective observations from three recurrent PMP cases further suggested the potential therapeutic value of VEGFR2-targeted anti-angiogenic therapy. Overall, this study provides a comprehensive single-cell transcriptomic atlas of PMP and a resource for developing novel and combination therapeutic strategies.
2026-07-09 | Temporal Immune and Metabolic Shifts Drive the Anti-Tumor Efficacy of Resiquimod-Loaded Nanoparticles in Peritoneal Carcinomatosis.
Peritoneal carcinomatosis (PC) is an aggressive manifestation of advanced gynecological and gastrointestinal malignancies with high recurrence rates despite cytoreductive surgery and chemotherapy. We developed a cationic liposomal nanoparticle (DSTAP, ∼159 nm) to deliver and retain the toll-like receptor 7/8 agonist Resiquimod (R848) within the peritoneal cavity, aiming to modulate the tumor immune microenvironment (TIME) and improve therapeutic efficacy. DSTAP-R848 was evaluated in murine colorectal and ovarian PC models, alone or combined with oxaliplatin (Oxa). Survival, cure rates, and durable immunity following tumor rechallenge were assessed. Immune polarization was examined by incubating ascites and peritoneal fluid with naïve splenocytes, while flow cytometry and metabolomic profiling characterized intratumoral immune populations and metabolic changes. Combination therapy achieved cure rates of 80% in the colorectal model and 30% in the ovarian model, with no recurrence after rechallenge; Oxa monotherapy yielded no cures. Oxa+DSTAP-R848 increased CD8+ T cells and M1 macrophages, while reducing regulatory T cells and myeloid-derived suppressor cells. Immunosuppressive and glycolytic metabolites progressively declined, correlating with reduced tumor burden. Overall, DSTAP-R848 enhances chemotherapy efficacy by reshaping immune and metabolic pathways and promoting durable anti-tumor immunity in PC.
2026-07-01 | 1446 Intestinal Transplantation for End-Stage Recurrent Pseudomyxoma Peritonei: The Impact of Nutritional and Functional Status on Outcomes Following Intestinal Transplantation
Abstract Aim To evaluate how anthropometrics affect post-transplant outcomes in patients with PMP. Intestinal transplantation can extend survival in patients with advanced, recurrent PMP not amenable to cytoreduction. Patient selection is challenging as patients may survive many years with advanced disease, but delaying referral can preclude transplant. Traditional anthropometrics, such as BMI, may be inaccurate due to tumour mass. Method PMP referrals over a ten-year period were used to obtain anthropometric, demographic and survival data. Skeletal muscle area was measured using pre-transplant L3 CT-scans and adjusted for height to derive the skeletal muscle index (SMI). SMI was categorised as Normal, Class I or Class II depletion (n within 1SD, 2SD>n>1SD, n>2SD respectively) based on sex-adjusted values in a healthy population. Mid-Arm Muscle Circumference (MAMC), Grip Strength and Triceps Skin Fold Thickness (TSF) were also measured. Results Forty-nine referrals were reviewed. 17/49 patients (35%) were transplanted, 22% were listed but not transplanted (usually due to deterioration or debulking surgery), and 43% were never listed (unsuitable). Post-referral survival was significantly increased in the transplanted group compared to the non-listed group (median=4.01 and 0.76 years respectively). SMI, but not BMI, was significantly increased in the transplant group, and patients with normal SMI were more likely to be transplanted (χ2 df=2, p<0.05). SMI Class, MAMC, and TSF were not significantly associated with survival, or hospital/ICU length-of-stay. Conclusions Intestinal transplant for PMP can significantly extend survival. Nutritional status, particularly SMI, is linked to the decision for transplantation although there is limited evidence to support an association with improved post-transplant outcomes.
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Drug Discovery Landscape
3 orphan drug designations for Pseudomyxoma peritonei.
3 orphan drug designations for Pseudomyxoma peritonei.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
bromelain + acetylcysteine | small molecules | FDA | 2018-12-27 | — | MUCPharm Pty Ltd. |
Bromelain | proteins | EMA | 2018-12-14 | — | Mucpharm Europe Limited |
Acetylcysteine | small molecules | EMA | 2018-12-14 | — | Mucpharm Europe Limited |
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