About

Philip Martin is a faculty member in the Department of Agricultural and Resource Economics at UC Davis. His research focuses on agricultural economics, resource economics, and policy analysis. As a distinguished professor, he has contributed to the understanding of agricultural markets, resource management, and economic policies affecting agriculture. His work encompasses a broad range of topics within agricultural and resource economics, emphasizing policy implications and economic analysis related to agriculture and natural resources.

Research topics

• Medicine
• Internal medicine
• Oncology
• Cancer research
• Biology
• Immunology
• Chemistry
• Gastroenterology

Selected publications

• CD73 expression as a resistance mechanism in advanced EGFR-mutated non-small cell lung cancer

  Frontiers in Oncology · 2026-03-03

  articleOpen access

  Introduction: The ectoenzyme CD73 induces an immune-evasive tumor microenvironment and has been proposed to be modulated by EGFR-TKI treatment. In this exploratory study, we analyzed CD73 expression and related immune markers during sequenced EGFR-TKI treatment, including osimertinib, to identify potential biomarkers for CD73-based therapeutic opportunities in EGFR-resistant tumors. Methods: -mutated EGFR-TKI pretreated NSCLC patients were analyzed. Expression of CD73, CD39, HLA-E and NKp46 were mapped in tumor tissue from diagnosis, after progression on early-generation EGFR-TKIs and after progression on osimertinib given as next-line EGFR-therapy. Results: Samples from 51 patients were evaluable. Upon progression after first line EGFR-TKI, 25 patients had T790M-postive disease, 18 cases were negative and 8 had unknown T790M-status. CD73 and HLA-E were significantly higher expressed in epithelium, while CD39 and NKp46 showed higher expression in the stroma of the tumors. There was no significant difference in expression pattern for any marker from diagnosis to progression after first line EGFR-treatment, but tumors with non-T790M-resistance to first- or second-generation TKIs had a significantly higher level of CD73 than T790M-positive tumors before commencing osimertinib. Paired tissue samples pre- and post-osimertinib were available in only four cases, of which three cases showed increased expression of HLA-E and NKp46 after osimertinib, while 2 cases had an increase in CD73 expression. Conclusion: We demonstrated differential expression patterns among the immune markers and higher levels of CD73 in cases with non-T790M-resistance to EGFR-TKIs. Although a limited number of cases were included in these analyses, the results might point to a potential role of immune markers inducing an immunosuppressive environment and thereby contribute to development of resistance to TKIs, which in turn could have future therapeutic implications.

  PublisherOA PDFDOI

• California farmers are turning to nonfarm employers to fill lower wage seasonal jobs

  California Agriculture · 2025-06-18

  articleOpen access

  California’s agricultural employers hired an average 414,000 workers between 2018 and 2023 and reported an average 886,000 unique farmworkers each year, a ratio of 2.1 workers for each average or full-time equivalent (FTE) job. The ratio of two workers for each FTE job is stable, but a rising share of workers are brought to farms by nonfarm crop support firms, including farm labor contractors (FLCs). Farmers outsource seasonal and specialized tasks to crop support firms to save money by paying for labor and other services when they are needed. FLCs account for two-thirds of average crop support employment, which highlights the challenge of regulating the intermediaries whose average employment is about the same as for workers hired directly by crop farmers.

  PublisherOA PDFDOI

• Building relationships of trust? The experiences of military veterans claiming ‘interface first’ Universal Credit

  Journal of Social Welfare and Family Law · 2025-07-03

  articleOpen access

  Trust is a central consideration when understanding the administration of social security benefits and interactions between the Department for Work and Pensions (DWP) and claimants, which is increasingly digitalised. While this can have administrative advantages for the DWP and some claimants, less is known about how this digital shift impacts on the relationship between the DWP and claimants within the context of the DWP’s commitments to restore trust. This paper will draw on unique qualitative longitudinal data from interviews with military veterans to examine how they experience interactions with the DWP over time, with a particular focus on trust. We find that although interactions through the Universal Credit (UC) online journal have advantages for some, for those with more complex needs or complex benefits issues to resolve, online communication can create additional barriers to relationships of trust. Our research demonstrates how participants often required ‘analog’ support from friends, family, third sector organisations and DWP staff to navigate their claims. The existence of DWP Armed Forces Champions provides an example of how targeted support is needed alongside digital contact, and how the ‘interface first’ nature of UC must recognise the on-going importance of human interactions for rebuilding relationships of trust.

  PublisherOA PDFDOI

• Farm Guest Workers: US Experience

  Asia & the Pacific Policy Studies · 2025-06-14 · 3 citations

  articleOpen access1st authorCorresponding

  ABSTRACT The US was one of the first countries to develop farm guest worker programs with Bracero programs during WWI and WWII outside regular immigration laws, followed by the H‐2(A) farm guest worker programme included in immigration law in the 1950s. The US tried to legalise the farm workforce in the mid‐1980s, but wound up spreading unauthorized workers throughout US agriculture and the nonfarm economy. Fewer unauthorized farm workers arrived after the 2008–09 recession, which helped the H‐2A programme quadrupled to 400,000 jobs over the past decade, so that guest workers fill 20 percent of average US crop employment. The farm labour market is at a crossroads, and is considering options that include labour‐saving machines, aids to raise productivity and H‐2A workers, and changing to non‐labour‐intensive crops and importing labour‐more intensive commodities from lower‐wage countries.

  PublisherOA PDFDOI

• Migrant workers in agriculture

  Edward Elgar Publishing eBooks · 2024-07-23 · 1 citations

  book-chapter1st authorCorresponding

  This chapter examines the employment of hired workers in agriculture in the US and other high-income countries. Agriculture employs a quarter of the world’s 3.3 billion workers, and almost half of the 825 million people employed in global agriculture are wage workers. As incomes rise, employment in agriculture shrinks, the production of farm commodities becomes concentrated on fewer and larger farms, and the share of farm work done by hired or wage workers increases. Many hired farm workers are migrants, moving from poorer to richer places within countries and from poorer to richer countries to fill seasonal farm jobs. Most countries made exceptions to otherwise closed borders during the covid pandemic to admit foreign farm workers. This chapter emphasises the growing role of international migrants who move from poorer to richer countries to fill especially seasonal jobs on farms.

  PublisherDOI

• Abstract 2023: Multiplex immunofluorescence profiling of the tumor microenvironment and CD73: Activity of neoadjuvant oleclumab in patients with non-small-cell lung cancer in NeoCOAST

  Cancer Research · 2024-03-22

  article

  Abstract Background: The NeoCOAST study (NCT03794544) investigated the efficacy of neoadjuvant immuno-oncology combinations in patients with resectable non-small-cell lung cancer (NSCLC), using major pathological response (MPR) as the primary endpoint (Cascone T, et al. Cancer Discov 2023;13:2394-411). Patients received a single cycle of the following treatments: durvalumab monotherapy (durva; anti-PD-L1), durva + oleclumab (ole; anti-CD73), or durva + monalizumab (mona; anti-NKG2A). Here we analyze the tumor microenvironment to investigate the mechanism of action of ole. Methods: A cohort of 47 patients (17 durva, 13 durva + mona, 17 durva + ole) with tumor tissue samples from pre-treatment (baseline, n=31) and surgery (post-treatment, n=24; n=8 paired pre- and post-treatment samples) were evaluated. Tumor sections were stained with (1) multiplex immunofluorescence (Panel 1: CD8-PD-L1-PD1-CD68-Ki67-panCK, Panel 2: NKp46-CD20), (2) CD73 immunohistochemistry (IHC), and (3) NKG2A IHC. Stains were analyzed using deep learning algorithms, manual pathology, and digital pathology scoring, respectively. Results: All arms showed similar infiltration of tumors by T cells (CD8), B cells (CD20), NK cells (NKp46), and macrophages (CD68) at the pre-treatment time point (Kruskal-Wallis, p=0.5-0.9 n.s.). Percent CD73+ tumor cells (TCs) at baseline was correlated with increased B cell, T cell, NK cell, and macrophage abundance (Spearman’s Rho=0.4-0.6, p<0.05). Percent CD73+ TC and B cell abundance was higher in patients with MPR vs those without MPR in the durva + ole arm, but not in the durva monotherapy or durva + mona arms. Increased CD8 T cell and NK cell abundance was not associated with MPR in any arm. Moreover, comparison of baseline to post-treatment tumor samples revealed a greater increase in CD8 T cells in the durva + ole arm (FC=2.1, p=0.02), particularly in proliferating activated T cells (CD8+Ki67+PD-1+; FC=8.0, p=0.003), compared to durva alone (FC=1.8, p=0.4 and FC=2.9, p=0.04, respectively). Conclusion: Increased abundance of CD73+ TCs is correlated with high B cells in the tumor microenvironment and associated with patients who experienced MPR in the durva + ole arm. Treatment with neoadjuvant durva + ole results in a greater increase in proliferating CD8 T cells than durva alone. Citation Format: Ina Bisha, Tze Heng Tan, Manuela Weitkunat, Alma Andoni, Iris Dino, Philip Martin, Megha Saraiya, Karma DaCosta, Pallavi Sontakke, Markus Schick, Michael Surace, Jorge Blando, Italia Grenga, Rakesh Kumar, Lara McGrath. Multiplex immunofluorescence profiling of the tumor microenvironment and CD73: Activity of neoadjuvant oleclumab in patients with non-small-cell lung cancer in NeoCOAST [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2023.

  PublisherDOI

• US Farm Employment and Farm Workers

  2024-06-17 · 5 citations

  reference-entry1st authorCorresponding

  Abstract The average employment of hired workers in US agriculture is about 1.5 million. Farm labor markets are significantly different from most other labor markets. For example, they are spread out over a wide geographic region, and the demand for labor depends upon a number of factors, including weather, wages, and the price of goods in some cases. Due to the seasonality of agricultural production and job turnover, some 2.5 million people are employed for wages on US farms sometime during a typical year. The employment of hired farm workers is concentrated in three interrelated ways: by geography, commodity, and size of farm. The 10,000 largest fruit and berry, vegetable and melon, and horticultural specialty (FVH) farms in California, Washington, Florida, and Texas account for over half of US farm worker employment, including a third in California. Two million farm workers, 80 percent of the total, are employed on crop farms. The National Agricultural Worker Survey (NAWS) finds that 70% of non-H-2A guest workers on US crop farms are Mexican-born men who have settled in one US place. Some 60 percent of these Mexican-born crop workers are unauthorized, making over 40 percent of non-H-2A crop workers unauthorized. If we consider all farm workers, including H-2A guest workers and hired workers employed in animal agriculture, the unauthorized share is lower, between 30 and 40 percent. Most settled Mexican-born farm workers have US-educated children who shun their parents’ seasonal farm jobs. According to US Census data, since the turn of the Great Recession, the non-citizen Mexican immigrant population has been declining, while the total number of Mexican immigrants started declining in 2016 (see Figure 1).

  PublisherDOI

• California has 882,000 farmworkers to fill 413,000 jobs

  California Agriculture · 2024-01-01 · 17 citations

  articleOpen access

  California's agricultural employers hired an average of 413,000 workers between 2018 and 2021 and reported an average of 882,000 farmworkers during these years, a ratio of 2.1 workers for each job. Average agricultural employment has been relatively stable since 2000, while the number of workers reported by agricultural employers declined. Despite concerns about farm labor shortages, the data show a relatively stable pool of farmworkers, including a rising share who are brought to farms by farm labor contractors.

  PublisherOA PDFDOI

• Fruit

  2023-10-19

  book-chapter1st authorCorresponding

  Abstract American households or consumer units spend an average $12 a week on fresh fruits and vegetables. Farmers receive a third of the retail price of apples and lettuce, and farm labor costs are a third of farm revenue, so a $2 pound of apples or a $2 head of lettuce generates $0.66 for farmers and $0.22 for farm workers. The choice between machines, migrants, and imports varies by commodity. Blueberry and raisin grape farms are likely to mechanize because machines are available and imports limit price increases, while apple, table grape, and strawberry farms are likely to employ more migrant guest workers until a combination of biological and engineering advances leads to mechanization in these commodities.

  PublisherDOI

• Antitumor activity of AZD0754, a dnTGFβRII-armored, STEAP2-targeted CAR-T cell therapy, in prostate cancer

  Journal of Clinical Investigation · 2023-11-15 · 49 citations

  articleOpen access

  Prostate cancer is generally considered an immunologically "cold" tumor type that is insensitive to immunotherapy. Targeting surface antigens on tumors through cellular therapy can induce a potent antitumor immune response to "heat up" the tumor microenvironment. However, many antigens expressed on prostate tumor cells are also found on normal tissues, potentially causing on-target, off-tumor toxicities and a suboptimal therapeutic index. Our studies revealed that six-transmembrane epithelial antigen of prostate-2 (STEAP2) was a prevalent prostate cancer antigen that displayed high, homogeneous cell surface expression across all stages of disease with limited distal normal tissue expression, making it ideal for therapeutic targeting. A multifaceted lead generation approach enabled development of an armored STEAP2 chimeric antigen receptor T cell (CAR-T) therapeutic candidate, AZD0754. This CAR-T product was armored with a dominant-negative TGF-β type II receptor, bolstering its activity in the TGF-β-rich immunosuppressive environment of prostate cancer. AZD0754 demonstrated potent and specific cytotoxicity against antigen-expressing cells in vitro despite TGF-β-rich conditions. Further, AZD0754 enforced robust, dose-dependent in vivo efficacy in STEAP2-expressing cancer cell line-derived and patient-derived xenograft mouse models, and exhibited encouraging preclinical safety. Together, these data underscore the therapeutic tractability of STEAP2 in prostate cancer as well as build confidence in the specificity, potency, and tolerability of this potentially first-in-class CAR-T therapy.

  PublisherOA PDFDOI

Frequent coauthors

• Maureen Baran

  93 shared

• Terry Van Dyke

  93 shared

• Jerome Schlomer

  National Cancer Institute

  80 shared

• Theresa M. Guerin

  Frederick National Laboratory for Cancer Research

  77 shared

• Zoë Weaver Ohler

  Frederick National Laboratory for Cancer Research

  54 shared

• Deborah B. Householder

  National Institutes of Health

  53 shared

• Ming Yi

  Huazhong University of Science and Technology

  52 shared

• Rajaâ El Meskini

  Frederick National Laboratory for Cancer Research

  50 shared

Education

• Ph.D.

  University of Wisconsin, Madison

  1975