Immunotherapy: The Silver Bullet Against Cancer?

Session Context & Participants

• Hosted by Dr. Jonathan Simons (President/CEO, Prostate Cancer Foundation) as part of a Milken-supported session on "Immunotherapy, the Silver Bullet Against Cancer."
• Panelists include Dr. Pam Sharma (MD Anderson), Dr. Jed Wolchuk (Memorial Sloan Kettering), Dr. Charles Drake (Hopkins), and Elliot Siegel (former CSO, Bristol-Myers Squibb).
• The panel emphasizes a shared bond of transitioning from traditional "genetic disease" models to immune-centric treatment paradigms.

Historical Breakthroughs & Efficacy Data

• Dr. William Coley achieved early success in the 1890s by injecting bacteria into tumors, though results were unpredictable compared to modern checkpoint inhibitors.
• Dr. Jim Allison's 1996 discovery of blocking the CTLA-4 molecule (the "off switch") paved the way for ipilimumab (Yervoy), approved by the FDA in 2011.
• Yervoy Outcome: Cures approximately 20% of terminal melanoma patients, extending survival to 3+ years and beyond 10 years for some, compared to a prior median life expectancy of 7–8 months.
• Impact Scale: If all eligible metastatic melanoma patients received Yervoy in 2012, it would have saved an estimated 1,500 to 1,700 lives annually.
• Patient Testimonials: Stage 4 melanoma patient TJ Sharp experienced complete remission after a poor prognosis, regaining the ability to run 5 miles; glioblastoma patient Mary has been disease-free for 7 years following Dr. Keith Black's dendritic cell vaccine.

Expansion to Other Tumor Types

• Kidney Cancer: Anti-PD-1 (nivolumab) shows a ~30% response rate as a single agent, with patients surviving 3 to 5 years post-treatment.
• Lung Cancer: Approximately 200,000 new cases annually; with a 20% response rate to anti-PD-1, roughly 40,000 patients could survive 2–3 years, with 20,000 likely alive who otherwise would not be.
• Prostate & Pancreatic Cancer: Historically resistant to single-agent immunotherapy; current focus is on understanding why T-cells fail to infiltrate these "cold" tumors.
• Combination Therapy: Melanoma trials combining anti-CTLA-4 and anti-PD-1 show disease control in 65% of patients and complete remissions in 15–20%, a significant increase over single-agent 20% rates.

Challenges & Disagreements Regarding Clinical Practice

• Patient Refusal of Chemo: Clinicians report melanoma patients increasingly refusing standard chemotherapy to prioritize immunotherapy, forcing trial protocol adjustments to allow participation without prior chemo failure.
• Non-Inflammatory Tumors: A major hurdle exists for lung, colon, and prostate cancers where the tumor microenvironment does not initially attract immune cells, requiring "priming" via radiation, chemotherapy, or targeted inhibitors.
• Trial Design Inefficiency: Experts argue current trials are too serial and siloed; they advocate for parallel testing of multiple combinations with uniform protocols to accelerate data acquisition.
• Regulatory Endpoints: Dr. Drake and others propose shifting FDA approval criteria from long-term "overall survival" (which takes 5+ years) to "milestone analysis" (percentage of patients alive at 2 or 3 years) to speed up access.

Funding & Government Disconnect

• NCI Allocation Disparity: Despite the "Breakthrough of the Year" designation, immunotherapy research accounts for only ~0.8 pages of the NCI's 83-page annual budget summary, contrasting sharply with 40% of NIH spending on HIV.
• Grant Review Bias: NIH grant reviewers often dismiss immunotherapy proposals as "fishing expeditions" or overly ambitious due to a lack of peer expertise in the field and a lingering bias from past failed vaccine trials.
• Talent Drain: The lack of R01 funding for early-career immunologists risks losing a generation of scientists, necessitating continued support from private foundations like PCF and MRA.

Future Directives & Call to Action

• Prescription for Research: Immediate need to test combination therapies (e.g., checkpoint inhibitors + radiation + hormonal therapy) rather than single agents for non-immunogenic cancers.
• Systemic Trial Changes: Advocacy for smaller, mechanism-focused trials (e.g., 12-patient cohorts) to analyze tumor immune infiltrates quickly, bypassing the need for large, long-term survival trials for initial biological validation.
• Biopharma & Govt Collaboration: Urgent need to break disciplinary silos between immunology and oncology, with biopharma doubling down on immuno-oncology portfolios and the government increasing investment in immune system sequencing.
• Emerging Therapies: T-cell receptor (CAR-T) therapy is considered promising but currently limited to hematologic cancers; solid tumor application requires overcoming safety and delivery challenges.
• Personalized Medicine: Future selection of patients will likely rely on "immunoprofiling" to identify specific checkpoints (e.g., PD-1 vs. LAG-3) expressed by a patient's specific tumor.