Setup

Arvinas (ARVN) is a targeted protein degradation biotech. On May 1, 2026, FDA approved VEPPANU (vepdegestrant) for ESR1-mutated metastatic breast cancer — the first rationally-designed protein degrader ever approved. The Q1 2026 10-Q, filed May 11, surfaced material new disclosures the market hasn't synthesized. Stock at $9.08; market cap ≈$935M; effective cash ≈$639M; pipeline implied EV ≈$295M.

What the filing says

The FDA approval triggered a $50M milestone from Pfizer. Net of ≈$7.5M Yale royalty, the first cash milestone ever paid on a PROTAC. NCCN Category 2A listing for VEPPANU came May 8 — seven days post-approval. NCCN is the gating step for payer coverage; a week is exceptionally fast and suggests oncology society pre-positioning.

ARV-393, the BCL6 PROTAC in lymphoma, disclosed its first clinical responses. Quote: "multiple responses observed in early cohorts at doses below the predicted effective exposure levels in patients with both B- and T-cell lymphomas." BCL6 has been undruggable for two decades. "Below predicted exposure" is mechanistically consequential — degraders process targets sub-stoichiometrically (one molecule destroys many), so responses at sub-modeled exposures indicate the catalytic mechanism is operational.

Commercial-partner language firmed. February 10-K: "planning to select" a third party for VEPPANU commercialization. May 10-Q: "remain on track to announce selection of a third party." NCCN listing + $50M milestone + Yale royalty trigger create urgency to close.

Pipeline activity continued. R&D spend on ARV-806 (KRAS G12D PROTAC) jumped to $6.5M from $0.9M YoY; dose escalation completed Q2 2026 as a subsequent event. ARV-393 spend $3.7M (+42% YoY). ARV-027 Phase 1 initiated — first PROTAC in Kennedy's disease.

The one new bear: ARV-102 (LRRK2 PROTAC for Parkinson's) U.S. Phase 1b for PSP placed on FDA clinical hold — chronic NHP toxicology data completeness, no safety signal, no patients dosed. EU program unaffected. Cross-checked all major TPD names (KYMR, NRIX, CCCC, BHVN, GLUE, FHTX) — zero active TPD clinical holds. Isolated to first-in-modality-and-route CNS-penetrant PROTAC.

Financials: Q1 2026 net cash $639M post-milestone post-Pfizer-cost-share; runway H2 2028. R&D -34% YoY, G&A -28%. $100M annualized restructuring savings materializing.

What the market thinks

Stock $9.08 → ≈$935M market cap → ≈$295M EV for the pipeline. Stock is down 17% in the month after FDA approval. 1Y peer comparison: KYMR +174%, GLUE +369%, CCCC +158%, ARVN +45%. The only TPD name with an FDA approval is the worst-performing in its modality basket.

Options tape: P/C ratio 0.10, call IV ≈13% above put IV — rare configuration consistent with sophisticated long-convexity positioning.

Reverse-engineering market-implied probabilities to fit $9.08 ≈ flat-EV pricing: market is roughly 2% homerun / 8% bull / 30% base / 40% weak / 20% bear. Market-implied 12mo EV: ~+10%.

Our scenario distribution: 10% / 25% / 35% / 20% / 10% → analyst EV ~+55%. Edge concentrated in market underweighting bull/homerun states (combined +25 percentage points) and overweighting weak/bear (-30 points).

Why the gap exists

1. The Pfizer-deprioritization narrative from September 2025 still dominates. Pfizer cut 15% of workforce tied to vepdegestrant commercialization and signaled weak commercial economics. Market anchored here and not pricing the regulatory event (approval delivered, NCCN listed, milestone triggered) that came after.

2. The ARV-393 disclosure is fresh and unsynthesized. The "multiple responses below predicted exposure" language sits in the MD&A pipeline section. Sell-side covers ARVN as a vepdegestrant story; ARV-393 is a footnote. The cross-ticker pattern — KYMR KT-621 picomolar potency, BHVN BHV-1400 deep response at first/lowest dose, CCCC cemsidomide at 75-100μg, GLUE MRT-8102 85% CRP reduction at low exposure — exists in five separate Q1 2026 filings but is not synthesized as a modality-wide feature.

3. The cash backstop isn't being priced as a floor. With $639M effective cash and burn ≈$277M/yr, the absolute downside in a partner-search-failure case is bounded. Market is treating ARVN like a binary catalyst stock rather than a cash-rich biotech with multiple shots.

Risks (ranked by impact)

1. Partner announced at humiliating terms ($50-100M upfront, single-digit royalty back to ARVN). Market reads "Pfizer dictated, ARVN had no leverage." Stock to $5-7. ≈25-30%.
2. ARV-393 ASH data soft (ORR <15%, short durability). Pipeline re-rate fails. ≈30-35%.
3. TPD M&A wave passes ARVN. Re-rate slower via relative re-pricing. ≈50%.
4. ARV-102 chronic NHP tox reveals safety finding. Bear for CNS-PROTAC; idio to ARV-102. ≈10%.
5. Forced dilutive raise. Cash runway protects but management could pre-empt at $9-10. ≈10%.

Catalysts

Five material events cluster Q3-Q4 2026. Most asymmetric: any 8-K naming a commercial partner re-rates the stock 25-50% on the day.

What would change our mind

Bear:

• Partner announced with $50M or less upfront and low royalty
• ARV-393 ASH abstract showing ORR <15%
• ARV-102 chronic NHP tox reveals safety signal (not data-completeness)
• Pfizer 8-K signaling partner-search failure or material delay
• Form 4 code S (open-market sale) from new CEO Teel or independent directors
• Material XBI drawdown >20% (sector beta hits)

Bull:

• Partner announced with $150M+ upfront
• Form 4 code P from Teel — informed buying at trough by the operator running the partner search
• TPD M&A bid hits any basket name with material premium

Evidence