The first 60 days: Systemic mastocytosis
Systemic mastocytosis is a clonal disease of mast cells, the immune cells that release histamine; almost every case is driven by a single mutation in the KIT gene. Precise KIT-blocking pills now shrink the mast cell burden, ease symptoms and, in the aggressive forms, prolong life. Most patients have the indolent form, where the goal is controlling symptoms and preventing anaphylaxis. Below, week by week, is what OnCo's record of Systemic mastocytosis says about the first two months: the order is typical, the timing is yours to ask about. Sections appear only where the record has something to say. Orientation, not medical advice.
What happens now
Staging tests establish exactly what and where the cancer is. Everything else follows from the answers.
Ask which of these were tested and what the results were; see the report reader for what each value means.
These specialties appear in the standard of care for this cancer. In most centres they meet weekly as a tumour board to agree each plan; you can ask when yours was discussed and what was decided.
- Medical oncologistNamed in the standard of care for: Indolent SM, symptomatic, Advanced SM, first line, Advanced SM, subsequent lines, SM-AHN.
- Transplant and cell therapy teamNamed in the standard of care for: Advanced SM, subsequent lines, SM-AHN.
A second opinion from a centre that treats many similar cases is normal, not rude; the standard of care tells you what to compare it against.
Each row is a setting from the standard of care, in the order it usually arises. Not all will apply to you; your stage and biomarkers decide which do. The guideline grade, where recorded, says how strong the evidence is.
- 1.Indolent SM, symptomaticNCCN category Category 2A, NCCN Guidelines: Systemic Mastocytosis; PIONEER (NEJM Evidence 2023)
H1 and H2 antihistamines, cromolyn, leukotriene antagonists, omalizumab for anaphylaxis, epinephrine autoinjector, bone protection; avapritinib 25 mg daily for moderate to severe symptoms uncontrolled by these (PIONEER).
- 2.Advanced SM, first lineNCCN category Category 2A (preferred: avapritinib), NCCN Guidelines: Systemic Mastocytosis; PATHFINDER (Nature Medicine 2021)
Avapritinib 200 mg daily (platelets above 50 x 10^9/L) as preferred agent; midostaurin as alternative or where platelets are low.
Switch between avapritinib and midostaurin; cladribine; clinical trials (bezuclastinib, elenestinib); allogeneic transplant for mast cell leukaemia or high-risk SM-AHN.
- 4.SM-AHN
Treat the dominant component: KIT inhibitor for mast cell burden plus the standard therapy for the associated CMML, MDS or AML (hypomethylating agents, intensive chemotherapy, transplant).
Generated from this cancer's standard of care, biomarkers and open problems. Take the group that matches where you are. To tick, add your own and print, open the one-page appointment sheet.
Newly diagnosed
- What is my exact diagnosis, stage, and grade, and which tests established them?Everything else follows from an accurate stage and subtype.
- Which biomarkers have been tested on my tumour (for example Serum tryptase, KIT D816V by high-sensitivity ddPCR in blood, Marrow mast cell aggregates with CD25, CD2, CD30 expression, C-findingsdefining advanced disease, SRSF2, ASXL1, RUNX1mutations; MARS and IPSM prognostic scores), and what were the results?These results decide eligibility for targeted therapy, immunotherapy, and trials.
- Which subtype is my cancer, and does that change the recommended treatment?Recognised subtypes for this cancer include Indolent systemic mastocytosis, Bone marrow mastocytosis, Smouldering systemic mastocytosis.
- Is germline (inherited) genetic testing recommended for me or my family?Inherited variants can change treatment and matter for relatives.
Indolent SM, symptomatic
- For my situation (indolent sm, symptomatic), which of the standard options do you recommend and why?Guideline options include: H1 and H2 antihistamines, cromolyn, leukotriene antagonists, omalizumab for anaphylaxis, epinephrine autoinjector, bone protection; avapritinib 25 mg daily for moderate to severe symptoms uncontrolled by these (PIONEER).
- Am I a candidate for Avapritinib, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Advanced SM, first line
- For my situation (advanced sm, first line), which of the standard options do you recommend and why?Guideline options include: Avapritinib 200 mg daily (platelets above 50 x 10^9/L) as preferred agent; midostaurin as alternative or where platelets are low.
- Am I a candidate for Avapritinib, Midostaurin, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Advanced SM, subsequent lines
- For my situation (advanced sm, subsequent lines), which of the standard options do you recommend and why?Guideline options include: Switch between avapritinib and midostaurin; cladribine; clinical trials (bezuclastinib, elenestinib); allogeneic transplant for mast cell leukaemia or high-risk SM-AHN.
- Am I a candidate for Cladribine, Midostaurin, Avapritinib, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
SM-AHN
- For my situation (sm-ahn), which of the standard options do you recommend and why?Guideline options include: Treat the dominant component: KIT inhibitor for mast cell burden plus the standard therapy for the associated CMML, MDS or AML (hypomethylating agents, intensive chemotherapy, transplant).
- Am I a candidate for Azacitidine, Avapritinib, and what side effects should I expect?Knowing the expected toxicities helps you plan work, family, and supportive care.
Any stage
- Are there clinical trials I could join, for example of Avapritinib, Allogeneic stem cell transplantation, Elenestinib?Trials are how the next standard of care is set; asking early keeps options open.
- Would a second opinion at a high-volume centre change anything, and can you help arrange it?Rare or high-stakes decisions benefit from a centre that treats many similar patients.
- What supportive care (symptom control, nutrition, exercise, mental health, financial help) is available from the start?Supportive care improves quality of life and helps patients complete treatment.
- I read that “Avapritinib carries intracranial bleeding risk at low platelet counts and cognitive effects; bezuclastinib and elenestinib are designed to avoid them”. How does that affect my plan?Open problems are where trials and second opinions matter most.
- I read that “The associated neoplasm in SM-AHN, not the mast cells, usually determines survival; combination strategies with hypomethylating agents and transplant are being studied”. How does that affect my plan?Open problems are where trials and second opinions matter most.
Trials open now for this cancer in OnCo, largest phase first. Joining a trial is a decision like any other: ask what the comparison arm is, whether a placebo is used, and what happens if you leave. The cancer page searches ClinicalTrials.gov live for more.
- (HARBOR) Study to Evaluate Efficacy and Safety of BLU-263 Versus Placebo in Patients With Indolent Systemic MastocytosisPhase 2/3 · recruiting · NCT04910685A Randomized, Double-Blind, Placebo-Controlled Phase 2/3 Study of BLU-263 in Indolent Systemic Mastocytosis
- (Apex) Bezuclastinib in Patients With Advanced Systemic MastocytosisPhase 2 · recruiting · NCT04996875A Phase 2 Open-Label, Multicenter Clinical Study of the Safety, Efficacy, Pharmacokinetic, and Pharmacodynamic Profiles of CGT9486 as a Single Agent in Patients With Advanced Systemic Mastocytosis
- (PIONEER) Study to Evaluate Efficacy and Safety of Avapritinib (BLU-285), A Selective KIT Mutation-targeted Tyrosine Kinase Inhibitor, Versus Placebo Phase 2 · active · NCT03731260A 3-Part, Randomized, Double-Blind, Placebo-Controlled Phase 2 Study to Evaluate Safety and Efficacy of Avapritinib (BLU-285), a Selective KIT Mutation-Targeted Tyrosine Kinase Inhibitor, in Indolent and Smoldering Systemic Mastocytosis With Symptoms Inadequately Controlled With Standard Therapy
- (Summit) A Study to Evaluate the Efficacy and Safety of CGT9486 Versus Placebo in Patients With Indolent or Smoldering Systemic MastocytosisPhase 2 · active · NCT05186753A Multi-Part, Randomized, Double-Blind, Placebo-Controlled Phase 2 Clinical Study of The Safety and Efficacy of CGT9486 in Subjects With Nonadvanced Systemic Mastocytosis
Much of what helps in the first weeks is free if you know to ask: testing, helplines, rides and lodging, second opinions, trial travel.
- Systemic mastocytosis: the full pageSystemic mastocytosis is a clonal disease of mast cells, the immune cells that release histamine; almost every case is driven by a single mutation in the KIT gene. Precise KIT-blocking pills now shrink the mast cell burden, ease symptoms and, in the aggressive forms, prolong life. Most patients have the indolent form, where the goal is controlling symptoms and preventing anaphylaxis.
- One-page appointment sheetYour questions, the words you may hear, what to bring, and space for the answers. Print it.
- Treatment sequencingWhich treatment tends to follow which, line by line.
- NavigatorStandard of care for your stage, what you have tried, and trials near you.
- Molecular response (MMR, MR4, treatment-free remission): In chronic myeloid leukaemia, how far the leukaemia gene signal in the blood has fallen, measured in logs: a 1,000-fold drop is a major molecular response, a 10,000-fold drop (MR4) is 'deep'.
- Driver mutation: One of the few mutations in a tumour that actually causes it to grow.
- Cytopenias and myelosuppression: The umbrella term for low blood counts of any kind (white cells, red cells, platelets) when treatment suppresses the bone marrow.
Every term links to the glossary.