# Heather Kay Lauren — Treatment Options Research
**Patient:** Heather Kay Lauren
**Diagnosis:** Stage 4 Gastric Adenocarcinoma, liver/brain metastases
**Pathology:** pMMR/MSS (microsatellite stable), **HER2 3+**
**Status (June 2026):** Disease progression, delirium episodes
**Caregiver:** Ashley Apsey
---
## Clinical Profile Summary
### Key Lab Findings (June 22, 2026)
| Test | Result | Normal | Concern |
|---|---|---|---|
| D-Dimer | **6,279** | ≤500 | Massive — VTE/thrombosis risk |
| Alk Phosphatase | **1,443** | 34–104 | 14x normal — liver/bone involvement |
| LDH | **422** | 140–271 | Tissue turnover/tumor burden |
| ALT | **46** | 7–25 | Hepatocyte injury |
| Sodium | **133** | 136–145 | Mild hyponatremia |
| Bilirubin | **0.29** | 0.20–1.10 | ✓ Preserved |
| eGFR | **141.9** | >60 | ✓ Renal function preserved |
### Disease Context
- HER2 3+ = **strongly positive** — qualifies for all HER2-targeted therapies
- pMMR/MSS = immunotherapy monotherapy less effective (but combo with trastuzumab still indicated)
- Brain metastases = requires CNS-penetrating therapy
- Liver metastases = driving the massive Alk Phos elevation
- Delirium episodes = may indicate active brain involvement or metabolic effects
---
## HER2-Targeted Treatment Options
### 1. Trastuzumab (Herceptin) — First-Line Foundation
**Type:** Monoclonal antibody
**Administration:** IV infusion every 2–3 weeks
**Evidence:** TOGA trial — first HER2+ gastric cancer trial, established standard of care
**Current Standard First-Line for HER2+:**
- **Trastuzumab + Pembrolizumab (Keytruda) + Chemotherapy**
- Pembrolizumab + trastuzumab + chemo approved for HER2+ advanced gastric cancer
- Keynote-811/Keynote-859 data showed significant OS benefit
- Chemotherapy backbone: typically fluoropyrimidine (5-FU/capecitabine) + platinum (oxaliplatin/cisplatin)
- pMMR/MSS status: pembrolizumab still effective in combo setting even without MSI-H
**Side Effects:**
- Trastuzumab: Cardiac toxicity (LVEF monitoring required), infusion reactions
- Pembrolizumab: Immune-related adverse events (colitis, hepatitis, pneumonitis, thyroiditis)
- Chemotherapy: Myelosuppression, nausea, neuropathy
---
### 2. Fam-trastuzumab Deruxtecan (Enhertu) — Second-Line and Beyond
**Type:** Antibody-drug conjugate (ADC) — HER2 antibody + topoisomerase I inhibitor
**Administration:** IV 6.4 mg/kg every 3 weeks
**FDA Indication:** HER2+ gastric/GEJ cancer after prior trastuzumab-containing regimen
**DESTINY-Gastric01 Results (Asian, 3rd+ line):**
- ORR: **66.7%** (vs. 10.5% for chemo control)
- Median PFS: **11.0 months** (vs. 4.0 months)
- Median OS: **21.0 months** (vs. 10.4 months)
- 2-year survival rate: **57.9%** (vs. 13.4%)
**DESTINY-Gastric02 Results (Western, 2nd line):**
- ORR: **41.8%**
- Median PFS: **5.6 months**
- Median OS: **12.1 months**
- Disease control rate: **81%**
**🧠 Brain Metastases Activity (Critical for Heather):**
- Enhertu demonstrates **significant CNS penetration**
- In breast cancer with brain mets (DESTINY-Breast12):
- CNS ORR: **71.7%**
- 12-month PFS: **61.6%** with brain mets
- 12-month OS: **90.3%**
- Active brain mets ORR: **54.7%** (untreated: 82.6%)
- Mechanism: ADC small enough to cross disrupted BBB; bystander killing effect
- Gastric cancer brain mets data still emerging, but mechanism is applicable
**⚠️ Major Safety Warning — ILD/Pneumonitis:**
- **10% incidence of ILD/pneumonitis** (Grade 1–5)
- **2.5% fatal ILD** in gastric trials
- Requires immediate workup of any cough, dyspnea, fever
- Grade ≥2 = **permanent discontinuation** + corticosteroids
**⚠️ Cardiac Monitoring:**
- Baseline echocardiogram/MUGA required
- Grade 2 LVEF decrease in ~10%
- No clinical heart failure reported but monitoring mandatory
**Other Side Effects:**
- Nausea (55%), fatigue (53%), decreased appetite (53%)
- Neutropenia (72%, Grade 3/4 in 51%)
- Febrile neutropenia: 4.8%
- Anemia (44%)
---
### 3. Tucatinib + Trastuzumab
**Type:** Oral HER2 TKI + monoclonal antibody
**Evidence:** HER2CLIMB trial (breast cancer) — significant CNS activity
- ORR in brain mets: 34.2% with tucatinib combo
- Intracranial ORR: 34.8%
- Reduced risk of intracranial progression
**Gastric cancer use:** Off-label but reasonable consideration given brain mets
---
### 4. Trastuzumab Deruxtecan — Emerging First-Line
**Current trials:**
- **DESTINY-Gastric03:** T-DXd + trastuzumab + chemo vs. trastuzumab + chemo as 1st line
- If approved, could skip trastuzumab alone and go straight to ADC + trastuzumab
---
## Angiogenesis Inhibitor
### Ramucirumab (Cyramza)
**Type:** VEGFR2 antagonist
**Use:** Second-line after chemotherapy failure
**RAINBOW Trial (Ramucirumab + Paclitaxel):**
- ORR: 28% vs. 7% (paclitaxel alone)
- Median OS: 9.6 months vs. 7.4 months
- Median PFS: 4.4 months vs. 2.8 months
**⚠️ Critical for Heather:**
- **Blood clot risk** — D-Dimer already at 6,279
- **GI perforation risk** — especially with advanced gastric cancer
- Use with extreme caution or contraindicated given massive thrombosis markers
---
## Clinical Trial Options
### Active HER2+ Gastric Cancer Trials (check clinicaltrials.gov):
1. **DESTINY-Gastric03** — T-DXd + trastuzumab + chemo as first-line
2. **DESTINY-Gastric04** — T-DXd vs. ramucirumab + chemo (2nd line)
3. **HER2CLIMB extensions** — Tucatinib + trastuzumab in gastric
4. **Multiple ADC combos** — Dual HER2 targeting, bispecific antibodies
### Biomarker-based trials:
- **CLDN18.2** testing (Zolbetuximab — but HER2+ precludes this)
- **NTRK fusion** testing (Larotrectinib/Entrectinib if positive)
- **MSI status re-check** (though MSS, sometimes changes)
---
## Supportive Care Considerations
### D-Dimer 6,279 — VTE Risk
- Consider **prophylactic anticoagulation** (LMWH)
- Given PTT elevation and possible heparin therapy, already on anticoagulation?
- D-Dimer this high = very high PE/DVT risk
- **Ramucirumab contraindicated** until D-Dimer controlled
### Liver Involvement
- Massive Alk Phos (1,443) with preserved bilirubin = infiltrative disease
- Monitor for biliary obstruction
- Consider palliative stenting if obstruction develops
### Brain Metastases / Delirium
- Dexamethasone for edema if symptomatic
- Neurosurgery consult for stereotactic radiosurgery (SRS) if focal lesions
- Enhertu has CNS activity — addresses brain mets systemically
### Delirium Management
- May be metabolic (hyponatremia, hepatic)
- May be primary CNS involvement
- May be medication-related
- Rule out infection, metabolic derangements, increased ICP
---
## Recommended Treatment Pathways
### If NOT on HER2 therapy yet (First-Line):
```
Trastuzumab + Pembrolizumab + Fluoropyrimidine/Platinum chemo
→ Monitor response every 8–12 weeks
→ If progression → Enhertu
```
### If already progressed on trastuzumab (Second-Line):
```
Enhertu (fam-trastuzumab deruxtecan) 6.4 mg/kg q3w
→ Monitor for ILD/pneumonitis aggressively
→ Requires baseline echo, then q9w monitoring
→ Brain MRI q8–12w to assess CNS response
```
### If brain mets are symptomatic/priority:
```
Local therapy (SRS/WBRT) + systemic HER2 therapy
OR
Enhertu (CNS penetration) ± tucatinib
```
---
## Key Questions for Oncology Team
1. Has Heather received trastuzumab-based therapy yet?
2. What line of treatment is she currently on?
3. Is she a candidate for Enhertu? (ECOG PS, LVEF, no prior ILD)
4. Given D-Dimer of 6,279 — is she on therapeutic anticoagulation?
5. Brain MRI done recently? Assessing for progression?
6. Consider clinical trial enrollment?
7. Palliative care consult for symptom management + quality of life?
---
**Disclaimer:** This is research compilation, not medical advice. All treatment decisions should be made by Heather's oncology team with full knowledge of her clinical status.
**Sources:**
- American Cancer Society (Feb 2026)
- NCI Stomach Cancer Treatment Guidelines
- DESTINY-Gastric01/02/03/04 trial data
- DESTINY-Breast01/12 trial data (CNS activity)
- FDA prescribing information for ENHERTU, trastuzumab, pembrolizumab